Development of SnS2/RGO nanosheet composite for cost-effective aqueous hybrid supercapacitors.

PubMed

Chauhan, Himani; Singh, Manoj K; Kumar, Praveen; Hashmi, Safir Ahmad; Deka, Sasanka

2017-01-13

The development of low cost supercapacitor cells with unique capacitive properties is essential for many domestic and industrial purposes. Here we report the first ever application of SnS 2 -reduced graphene oxide (SnS 2 /RGO) layered nanocomposite as a superior electrode material for symmetric aqueous hybrid supercapacitors. We synthesized SnS 2 /RGO nanocomposite comprised of nanosheets of SnS 2 and graphene oxide via a one-pot hydrothermal approach. in situ as-synthesized SnS 2 /RGO is devised for the first time to give high specific capacitance 500 Fg -1 , energy density 16.67 Wh kg -1 and power density 488 W kg -1 . The cell retains 95% charge/discharge cycle stability up to 1000 cycles. In-short, the SnS 2 /RGO nanosheet composite presented is a novel and advanced material for application in high stability moderate value hybrid supercapacitors. All the currently available surveys in literature state the potential applicability of SnS 2 as the anode material for reversible lithium/sodium ion batteries (LIBs/NIBs) but there is a lack of equivalent studies on electrochemical capacitors. We filled up this knowledge gap by the use of the same material in a cost-effective, highly active hybrid supercapacitor application by utilizing its pseudocapacitance property combined with the layered capacitance property of graphene sheets.

Ultra-flexible and robust transparent electrodes by embedding silver nanowires into polyimide matrix

NASA Astrophysics Data System (ADS)

Zhao, Rong Rong; Yu, Ming Shi; Wang, Guan Cheng; Liu, Wei; Chen, Tong Lai

2018-06-01

Silver nanowires (AgNWs) percolated films have been extensively considered as promising candidates for alternative transparent electrodes. However, due to their high surface roughness, poor adhesion and thermal stability, their practical use in transparent conducting film application is still heavily limited. In this paper, we report ultra-flexible transparent electrodes by imbedding AgNWs into polyimide (PI) thin films to achieve smooth surface, pronounced thermal stability, and high adhesion. Besides the excellent electrical conductivity of about 7-13Ω/□ in sheet resistance, the obtained AgNWs/PI films have excellent transparency and mechanical resilience due to the intrinsic physical and chemical properties of PI organic polymer. By embedding AgNWs into PI, the surface roughness of AgNWs percolated films can be reduced from 39.5 nm to 6 nm (RMS values), and the adhesion of AgNWs to PI is greatly enhanced if compared to the case of only AgNWs onto glass or plastic substrates. Additionally, the AgNWs/PI films show extraordinary stability in terms of electrical conductivity after the arbitrary twisting and thermal heating test, respectively, which are demonstrated by the electrical-thermal measurements via thermal IR imaging.

Recyclable patterning of silver nanowire percolated network for fabrication of flexible transparent electrode

NASA Astrophysics Data System (ADS)

Yoo, Byungwook; Kim, Youngmin; Han, Chul Jong; Oh, Min Suk; Kim, Jong-Woong

2018-01-01

Recent studies have revealed that silver nanowires (AgNWs) are a promising material for highly flexible transparent electrodes. Here we introduce a novel photoinduced recyclable approach to AgNW patterning to overcome the issue of loss of material during fabrication of AgNW patterns, which is a leading factor in the high fabrication costs of AgNW-based electrodes. Our patterning scheme involves the selective irradiation of an AgNW/polymer composite with high-intensity pulsed light, followed by immersion of the sample in a liquid and an ultrasonication treatment. The nanowires that detach during sonication could be recycled, and the recycled AgNWs achieved comparable performance to that of pristine AgNWs. The recycled AgNWs were also superior to commercial indium tin oxide films and other competing materials. We successfully demonstrated a high performance transparent heater by employing the recyclable patterning method and recycled AgNWs.

Synthesis of MoS2/rGO nanosheets hybrid materials for enhanced visible light assisted photocatalytic activity

NASA Astrophysics Data System (ADS)

Pal, Shreyasi; Dutta, Shibsankar; De, Sukanta

2018-04-01

A facile hydrothermal method has been adopted to synthesize pure MoS2 nanosheets and MoS2/rGO nanosheets hybrid. The samples were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (HRTEM), X-ray diffraction spectroscopy (XRD), Brunauer-Emmett-Teller (BET). The photocatalytic performance and reusability of MoS2 nanosheets and MoS2/rGO hybrids was evaluated by discoloring of RhB under visible light irradiation. Results indicated that MoS2/rGO photocatalysts with large surface area of 69.5 m2 g-1 could completely degrade 50 mL of 8 mg L-1 RhB aqueous solution in 90 min with excellent recycling and structural stability as compared with pure MoS2 nanosheets (53%). Such enhanced performance could be explained due to the high surface area, enhanced light absorption and the increased dye adsorptivity and reduced electron-hole pair recombination with the presence of rGO.

Transparent Electrodes Based on Silver Nanowire Networks: From Physical Considerations towards Device Integration

PubMed Central

Bellet, Daniel; Lagrange, Mélanie; Sannicolo, Thomas; Aghazadehchors, Sara; Nguyen, Viet Huong; Langley, Daniel P.; Muñoz-Rojas, David; Jiménez, Carmen; Bréchet, Yves; Nguyen, Ngoc Duy

2017-01-01

The past few years have seen a considerable amount of research devoted to nanostructured transparent conducting materials (TCM), which play a pivotal role in many modern devices such as solar cells, flexible light-emitting devices, touch screens, electromagnetic devices, and flexible transparent thin film heaters. Currently, the most commonly used TCM for such applications (ITO: Indium Tin oxide) suffers from two major drawbacks: brittleness and indium scarcity. Among emerging transparent electrodes, silver nanowire (AgNW) networks appear to be a promising substitute to ITO since such electrically percolating networks exhibit excellent properties with sheet resistance lower than 10 Ω/sq and optical transparency of 90%, fulfilling the requirements of most applications. In addition, AgNW networks also exhibit very good mechanical flexibility. The fabrication of these electrodes involves low-temperature processing steps and scalable methods, thus making them appropriate for future use as low-cost transparent electrodes in flexible electronic devices. This contribution aims to briefly present the main properties of AgNW based transparent electrodes as well as some considerations relating to their efficient integration in devices. The influence of network density, nanowire sizes, and post treatments on the properties of AgNW networks will also be evaluated. In addition to a general overview of AgNW networks, we focus on two important aspects: (i) network instabilities as well as an efficient Atomic Layer Deposition (ALD) coating which clearly enhances AgNW network stability and (ii) modelling to better understand the physical properties of these networks. PMID:28772931

Low-haze, annealing-free, very long Ag nanowire synthesis and its application in a flexible transparent touch panel

NASA Astrophysics Data System (ADS)

Moon, Hyunjin; Won, Phillip; Lee, Jinhwan; Ko, Seung Hwan

2016-07-01

Since transparent conducting films based on silver nanowires (AgNWs) have shown higher transmittance and electrical conductivity compared to those of indium tin oxide (ITO) films, the electronics industry has recognized them as promising substitutes. However, due to the higher haze value of AgNW transparent conducting films compared to ITO films, the clarity is decreased when AgNW films are applied to optoelectronic devices. In this study, we develop a highly transparent, low-haze, very long AgNW percolation network. Moreover, we confirm that analyzed chemical roles can easily be applied to different AgNW synthesis methods, and that they have a direct impact on the nanowire shape. Consequently, the lengths of the wires are increased up to 200 μm and the diameters of the wires are decreased up to 45 nm. Using these results, we fabricate highly transparent (96%) conductors (100 Ω/sq) with low-haze (2%) without any annealing process. This electrode shows enhanced clarity compared to previous results due to the decreased diffusive transmittance and scattering. In addition, a flexible touchscreen using a AgNW network is demonstrated to show the performance of modified AgNWs.

Capillary Printing of Highly Aligned Silver Nanowire Transparent Electrodes for High-Performance Optoelectronic Devices.

PubMed

Kang, Saewon; Kim, Taehyo; Cho, Seungse; Lee, Youngoh; Choe, Ayoung; Walker, Bright; Ko, Seo-Jin; Kim, Jin Young; Ko, Hyunhyub

2015-12-09

Percolation networks of silver nanowires (AgNWs) are commonly used as transparent conductive electrodes (TCEs) for a variety of optoelectronic applications, but there have been no attempts to precisely control the percolation networks of AgNWs that critically affect the performances of TCEs. Here, we introduce a capillary printing technique to precisely control the NW alignment and the percolation behavior of AgNW networks. Notably, partially aligned AgNW networks exhibit a greatly lower percolation threshold, which leads to the substantial improvement of optical transmittance (96.7%) at a similar sheet resistance (19.5 Ω sq(-1)) as compared to random AgNW networks (92.9%, 20 Ω sq(-1)). Polymer light-emitting diodes (PLEDs) using aligned AgNW electrodes show a 30% enhanced maximum luminance (33068 cd m(-2)) compared to that with random AgNWs and a high luminance efficiency (14.25 cd A(-1)), which is the highest value reported so far using indium-free transparent electrodes for fluorescent PLEDs. In addition, polymer solar cells (PSCs) using aligned AgNW electrodes exhibit a power conversion efficiency (PCE) of 8.57%, the highest value ever reported to date for PSCs using AgNW electrodes.

Fabrication of monolayer MoS2/rGO hybrids with excellent tribological performances through a surfactant-assisted hydrothermal route

NASA Astrophysics Data System (ADS)

Chen, Jinsuo; Xia, Yunfei; Yang, Jin; Chen, Beibei

2018-06-01

The extremely low friction between incommensurate two-dimensional (2D) atomic layers has recently attracted a great interest. Here, we demonstrated a promising surfactant-assisted strategy for the synthesis of MoS2/reduced graphene oxide (MoS2/rGO) hybrid materials with monolayer MoS2 and rGO, which exhibited excellent tribological metrics with a friction coefficient of ˜ 0.09 and a wear rate of ˜ 2.08 × 10-5 mm3/Nm in the ethanol dispersion. The incommensurate 2D atomic layer interface formed due to intrinsic lattice mismatch between MoS2 and graphene was thought to be responsible for the excellent lubricating performances. In addition to the benefits of unique hybrid structure, MoS2/rGO hybrids could also adsorb on metal surfaces and screen the metal-metal interaction to passivate the metal surfaces with a consequent reduction of corrosion wear during sliding. This work could pave a new pathway to design novel materials for pursuing excellent tribological properties by hybridizing different 2D atomic-layered materials.

Co-Percolating Graphene-Wrapped Silver Nanowire Network for High Performance, Highly Stable, Transparent Conducting Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Ruiyi; Das, Suprem R.; Jeong, Changwook

Transparent conducting electrodes (TCEs) require high transparency and low sheet resistance for applications in photovoltaics, photodetectors, flat panel displays, touch screen devices and imagers. Indium tin oxide (ITO), or other transparent conductive oxides, have typically been used, and provide a baseline sheet resistance (RS) vs. transparency (T) relationship. However, ITO is relatively expensive (due to limited abundance of Indium), brittle, unstable, and inflexible; moreover, ITO transparency drops rapidly for wavelengths above 1000 nm. Motivated by a need for transparent conductors with comparable (or better) RS at a given T, as well as flexible structures, several alternative material systems have beenmore » investigated. Single-layer graphene (SLG) or few-layer graphene provide sufficiently high transparency (≈97% per layer) to be a potential replacement for ITO. However, large-area synthesis approaches, including chemical vapor deposition (CVD), typically yield films with relatively high sheet resistance due to small grain sizes and high-resistance grain boundaries (HGBs). In this paper, we report a hybrid structure employing a CVD SLG film and a network of silver nanowires (AgNWs): RS as low as 22 Ω/ (stabilized to 13 Ω/ after 4 months) have been observed at high transparency (88% at λ = 550 nm) in hybrid structures employing relatively low-cost commercial graphene with a starting RS of 770 Ω/. This sheet resistance is superior to typical reported values for ITO, comparable to the best reported TCEs employing graphene and/or random nanowire networks, and the film properties exhibit impressive stability under mechanical pressure, mechanical bending and over time. The design is inspired by the theory of a co-percolating network where conduction bottlenecks of a 2D film (e.g., SLG, MoS2) are circumvented by a 1D network (e.g., AgNWs, CNTs) and vice versa. The development of these high-performance hybrid structures provides a route towards robust

Low thermal emissivity surfaces using AgNW thin films

NASA Astrophysics Data System (ADS)

Pantoja, Elisa; Bhatt, Rajendra; Liu, Anping; Gupta, Mool C.

2017-12-01

The properties of silver nanowire (AgNW) films in the optical and infrared spectral regime offer an interesting opportunity for a broad range of applications that require low-emissivity coatings. This work reports a method to reduce the thermal emissivity of substrates by the formation of low-emissivity AgNW coating films from solution. The spectral emissivity was characterized by thermal imaging with an FLIR camera, followed by Fourier transform infrared spectroscopy. In a combined experimental and simulation study, we provide fundamental data of the transmittance, reflectance, haze, and emissivity of AgNW thin films. Emissivity values were finely tuned by modifying the concentration of the metal nanowires in the films. The simulation models based on the transfer matrix method developed for the AgNW thin films provided optical values that show a good agreement with the measurements.

CuS/RGO hybrid photocatalyst for full solar spectrum photoreduction from UV/Vis to near-infrared light.

PubMed

Wu, Jie; Liu, Baibai; Ren, Zhenxing; Ni, Mengying; Li, Can; Gong, Yinyan; Qin, Wei; Huang, Yongli; Sun, Chang Q; Liu, Xinjuan

2018-05-01

To make full use of the solar energy, it remains a great challenge for semiconductor photocatalysts to harvest the full solar light spectrum from ultraviolet (UV) to visible even the near infrared (NIR) wavelength. Here we show firstly the CuS/RGO (reduced graphene oxide) hybrid photocatalyst synthesized via a microwave assisted method with full solar light (UV-Vis-NIR) active for efficient Cr(VI) reduction. The CuS/RGO displays high absorption and catalytic activity in the UV, visible and even the NIR light regions. As co-catalyst, RGO can separate and inhibit the recombination of charge carriers, consequently improving the catalytic activity. Only 1wt% RGO emersions can reduce 90% of Cr(VI) under the radiation of light over the full spectrum. Findings may provide a new strategy and substance to expand the utilization range of solar light from UV to visible even the NIR energy. Copyright © 2017. Published by Elsevier Inc.

Large-Area Cross-Aligned Silver Nanowire Electrodes for Flexible, Transparent, and Force-Sensitive Mechanochromic Touch Screens.

PubMed

Cho, Seungse; Kang, Saewon; Pandya, Ashish; Shanker, Ravi; Khan, Ziyauddin; Lee, Youngsu; Park, Jonghwa; Craig, Stephen L; Ko, Hyunhyub

2017-04-25

Silver nanowire (AgNW) networks are considered to be promising structures for use as flexible transparent electrodes for various optoelectronic devices. One important application of AgNW transparent electrodes is the flexible touch screens. However, the performances of flexible touch screens are still limited by the large surface roughness and low electrical to optical conductivity ratio of random network AgNW electrodes. In addition, although the perception of writing force on the touch screen enables a variety of different functions, the current technology still relies on the complicated capacitive force touch sensors. This paper demonstrates a simple and high-throughput bar-coating assembly technique for the fabrication of large-area (>20 × 20 cm 2 ), highly cross-aligned AgNW networks for transparent electrodes with the sheet resistance of 21.0 Ω sq -1 at 95.0% of optical transmittance, which compares favorably with that of random AgNW networks (sheet resistance of 21.0 Ω sq -1 at 90.4% of optical transmittance). As a proof of concept demonstration, we fabricate flexible, transparent, and force-sensitive touch screens using cross-aligned AgNW electrodes integrated with mechanochromic spiropyran-polydimethylsiloxane composite film. Our force-sensitive touch screens enable the precise monitoring of dynamic writings, tracing and drawing of underneath pictures, and perception of handwriting patterns with locally different writing forces. The suggested technique provides a robust and powerful platform for the controllable assembly of nanowires beyond the scale of conventional fabrication techniques, which can find diverse applications in multifunctional flexible electronic and optoelectronic devices.

Positively-charged reduced graphene oxide as an adhesion promoter for preparing a highly-stable silver nanowire film

NASA Astrophysics Data System (ADS)

Sun, Qijun; Lee, Seong Jun; Kang, Hyungseok; Gim, Yuseong; Park, Ho Seok; Cho, Jeong Ho

2015-04-01

An ultrathin conductive adhesion promoter using positively charged reduced graphene oxide (rGO-NH3+) has been demonstrated for preparing highly stable silver nanowire transparent conductive electrodes (AgNW TCEs). The adhesion promoter rGO-NH3+, spray coated between the substrate and AgNWs, significantly enhances the chemical and mechanical stabilities of the AgNW TCEs. Besides, the ultrathin thickness of the rGO-NH3+ ensures excellent optical transparency and mechanical flexibility for TCEs. The AgNW films prepared using the adhesion promoter are extremely stable under harsh conditions, including ultrasonication in a variety of solvents, 3M Scotch tape detachment test, mechanical bending up to 0.3% strain, or fatigue over 1000 cycles. The greatly enhanced adhesion force is attributed to the ionic interactions between the positively charged protonated amine groups in rGO-NH3+ and the negatively charged hydroxo- and oxo-groups on the AgNWs. The positively charged GO-NH3+ and commercial polycationic polymer (poly allylamine hydrochloride) are also prepared as adhesion promoters for comparison with rGO-NH3+. Notably, the closely packed hexagonal atomic structure of rGO offers better barrier properties to water permeation and demonstrates promising utility in durable waterproof electronics. This work offers a simple method to prepare high-quality TCEs and is believed to have great potential application in flexible waterproof electronics.An ultrathin conductive adhesion promoter using positively charged reduced graphene oxide (rGO-NH3+) has been demonstrated for preparing highly stable silver nanowire transparent conductive electrodes (AgNW TCEs). The adhesion promoter rGO-NH3+, spray coated between the substrate and AgNWs, significantly enhances the chemical and mechanical stabilities of the AgNW TCEs. Besides, the ultrathin thickness of the rGO-NH3+ ensures excellent optical transparency and mechanical flexibility for TCEs. The AgNW films prepared using the adhesion

High-performance microsupercapacitors based on two-dimensional graphene/manganese dioxide/silver nanowire ternary hybrid film.

PubMed

Liu, Wenwen; Lu, Congxiang; Wang, Xingli; Tay, Roland Yingjie; Tay, Beng Kang

2015-02-24

Microsupercapacitors (MSCs), as one type of significant power source or energy storage unit in microelectronic devices, have attracted more and more attention. However, how to reasonably design electrode structures and exploit the active materials to endow the MSCs with excellent performances in a limited surface area still remains a challenge. Here, a reduced graphene oxide (RGO)/manganese dioxide (MnO2)/silver nanowire (AgNW) ternary hybrid film (RGMA ternary hybrid film) is successfully fabricated by a facile vacuum filtration and subsequent thermal reduction, and is used directly as a binder-free electrode for MSCs. Additionally, a flexible, transparent, all-solid state RMGA-MSC is also built, and its electrochemical performance in an ionic liquid gel electrolyte are investigated in depth. Notably, the RGMA-MSCs display superior electrochemical properties, including exceptionally high rate capability (up to 50000 mV·s(-1)), high frequency response (very short corresponding time constant τ0 = 0.14 ms), and excellent cycle stability (90.3% of the initial capacitance after 6000 cycles in ionic liquid gel electrolyte). Importantly, the electrochemical performance of RGMA-MSCs shows a strong dependence on the geometric parameters including the interspace between adjacent fingers and the width of the finger of MSCs. These encouraging results may not only provide important references for the design and fabrication of high-performance MSCs, but also make the RGMA ternary hybrid film promising for the next generation film lithium ion batteries and other energy storage devices.

Stability Enhancement of Silver Nanowire Networks with Conformal ZnO Coatings Deposited by Atmospheric Pressure Spatial Atomic Layer Deposition.

PubMed

Khan, Afzal; Nguyen, Viet Huong; Muñoz-Rojas, David; Aghazadehchors, Sara; Jiménez, Carmen; Nguyen, Ngoc Duy; Bellet, Daniel

2018-06-06

Silver nanowire (AgNW) networks offer excellent electrical and optical properties and have emerged as one of the most attractive alternatives to transparent conductive oxides to be used in flexible optoelectronic applications. However, AgNW networks still suffer from chemical, thermal, and electrical instabilities, which in some cases can hinder their efficient integration as transparent electrodes in devices such as solar cells, transparent heaters, touch screens, and organic light emitting diodes. We have used atmospheric pressure spatial atomic layer deposition (AP-SALD) to fabricate hybrid transparent electrode materials in which the AgNW network is protected by a conformal thin layer of zinc oxide. The choice of AP-SALD allows us to maintain the low-cost and scalable processing of AgNW-based transparent electrodes. The effects of the ZnO coating thickness on the physical properties of AgNW networks are presented. The composite electrodes show a drastic enhancement of both thermal and electrical stabilities. We found that bare AgNWs were stable only up to 300 °C when subjected to thermal ramps, whereas the ZnO coating improved the stability up to 500 °C. Similarly, ZnO-coated AgNWs exhibited an increase of 100% in electrical stability with respect to bare networks, withstanding up to 18 V. A simple physical model shows that the origin of the stability improvement is the result of hindered silver atomic diffusion thanks to the presence of the thin oxide layer and the quality of the interfaces of hybrid electrodes. The effects of ZnO coating on both the network adhesion and optical transparency are also discussed. Finally, we show that the AP-SALD ZnO-coated AgNW networks can be effectively used as very stable transparent heaters.

Highly transparent and flexible circuits through patterning silver nanowires into microfluidic channels.

PubMed

Sun, Jing; Zhou, Wenhui; Yang, Haibo; Zhen, Xue; Ma, Longfei; Williams, Dirk; Sun, Xudong; Lang, Ming-Fei

2018-05-10

The development of flexible and transparent devices requires completely transparent and flexible circuits (TFCs). To overcome the disadvantages of the previously reported TFCs that are partially transparent, lacking pattern control, or labor consuming, we achieve true TFCs via a facile process with precise pattern control, exhibiting concurrent high transparency, conductivity, flexibility, stretchability, and robustness. A highly transparent and flexible conductive film is first made through spin coating silver nanowires (AgNWs) onto polydimethylsiloxane (PDMS), and demonstrates simultaneous high transparency (90.86%) and low sheet resistance (3.22 Ω sq-1). Taking advantage of microfluidic technology, circuits with ultraprecise and complex patterns from the microscale to milliscale are obtained through spin coating of AgNWs into microfluidic channels on PDMS. Without elaborate processing, this method may be suitable for mass production, which would contribute enormously to potential applications in wearable medical equipment and transparent electronic devices.

Plasticized Polymer Interlayer for Low-Temperature Fabrication of a High-Quality Silver Nanowire-Based Flexible Transparent and Conductive Film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jo, Wonhee; Kang, Hong Suk; Choi, Jaeho

Silver nanowires (AgNWs) are one of the most promising materials to replace commercially available indium tin oxide in flexible transparent conductive films (TCFs); however, there are still numerous problems originating from poor AgNW junction formation and improper AgNW embedment into transparent substrates. To mitigate these problems, high-temperature processes have been adopted; however, unwanted substrate deformation prevents the use of these processes for the formation of flexible TCFs. In this work, we present a novel poly(methyl methacrylate) interlayer plasticized by dibutyl phthalate for low-temperature fabrication of AgNW-based TCFs, which does not cause any substrate deformation. By exploiting the viscoelastic properties ofmore » the plasticized interlayer near the lowered glass-transition temperature, a monolithic junction of AgNWs on the interlayer and embedment of the interconnected AgNWs into the interlayer are achieved in a single-step pressing. The resulting AgNW-TCFs are highly transparent (~92% at a wavelength of 550 nm), highly conductive (<90 Ω/sq), and environmentally and mechanically robust. Therefore, the plasticized interlayer provides a simple and effective route to fabricate high-quality AgNW-based TCFs.« less

Aerosol jet printed silver nanowire transparent electrode for flexible electronic application

NASA Astrophysics Data System (ADS)

Tu, Li; Yuan, Sijian; Zhang, Huotian; Wang, Pengfei; Cui, Xiaolei; Wang, Jiao; Zhan, Yi-Qiang; Zheng, Li-Rong

2018-05-01

Aerosol jet printing technology enables fine feature deposition of electronic materials onto low-temperature, non-planar substrates without masks. In this work, silver nanowires (AgNWs) are proposed to be printed into transparent flexible electrodes using a Maskless Mesoscale Material Deposition Aerosol Jet® printing system on a glass substrate. The influence of the most significant process parameters, including printing cycles, printing speed, and nozzle size, on the performance of AgNW electrodes was systematically studied. The morphologies of printed patterns were characterized by scanning electron microscopy, and the transmittance was evaluated using an ultraviolet-visible spectrophotometer. Under optimum conditions, high transparent AgNW electrodes with a sheet resistance of 57.68 Ω/sq and a linewidth of 50.9 μm were obtained, which is an important step towards a higher performance goal for flexible electronic applications.

Silver-Nanowire-Embedded Transparent Metal-Oxide Heterojunction Schottky Photodetector.

PubMed

Abbas, Sohail; Kumar, Mohit; Kim, Hong-Sik; Kim, Joondong; Lee, Jung-Ho

2018-05-02

We report a self-biased and transparent Cu 4 O 3 /TiO 2 heterojunction for ultraviolet photodetection. The dynamic photoresponse improved 8.5 × 10 4 % by adding silver nanowires (AgNWs) Schottky contact and maintaining 39% transparency. The current density-voltage characteristics revealed a strong interfacial electric field, responsible for zero-bias operation. In addition, the dynamic photoresponse measurement endorsed the effective holes collection by embedded-AgNWs network, leading to fast rise and fall time of 0.439 and 0.423 ms, respectively. Similarly, a drastic improvement in responsivity and detectivity of 187.5 mAW -1 and of 5.13 × 10 9 Jones, is observed, respectively. The AgNWs employed as contact electrode can ensure high-performance for transparent and flexible optoelectronic applications.

Flexible organic light-emitting devices with a smooth and transparent silver nanowire electrode

NASA Astrophysics Data System (ADS)

Cui, Hai-Feng; Zhang, Yi-Fan; Li, Chuan-Nan

2014-07-01

We demonstrate a flexible organic light-emitting device (OLED) by using silver nanowire (AgNW) transparent electrode. A template stripping process has been employed to fabricate the AgNW electrode on a photopolymer substrate. From this approach, a random AgNW network electrode can be transferred to the flexible substrate and its roughness has been successfully decreased. As a result, the devices obtained by this method exhibit high efficiency. In addition, the flexible OLEDs keep good performance under a small bending radius.

All-solution processed semi-transparent perovskite solar cells with silver nanowires electrode.

PubMed

Yang, Kaiyu; Li, Fushan; Zhang, Jianhua; Veeramalai, Chandrasekar Perumal; Guo, Tailiang

2016-03-04

In this work, we report an all-solution route to produce semi-transparent high efficiency perovskite solar cells (PSCs). Instead of an energy-consuming vacuum process with metal deposition, the top electrode is simply deposited by spray-coating silver nanowires (AgNWs) under room temperature using fabrication conditions and solvents that do not damage or dissolve the underlying PSC. The as-fabricated semi-transparent perovskite solar cell shows a photovoltaic output with dual side illuminations due to the transparency of the AgNWs. With a back cover electrode, the open circuit voltage increases significantly from 1.01 to 1.16 V, yielding high power conversion efficiency from 7.98 to 10.64%.

Rapid synthesis of ultra-long silver nanowires for tailor-made transparent conductive electrodes: proof of concept in organic solar cells.

PubMed

José Andrés, Luis; Fe Menéndez, María; Gómez, David; Luisa Martínez, Ana; Bristow, Noel; Paul Kettle, Jeffrey; Menéndez, Armando; Ruiz, Bernardino

2015-07-03

Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 μm, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS = 20.2 Ω/sq), whilst maintaining high optical film transparency (T = 94.7%), driving to the highest reported figure-of-merit (FoM = 338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed.

Rapid synthesis of ultra-long silver nanowires for tailor-made transparent conductive electrodes: proof of concept in organic solar cells

NASA Astrophysics Data System (ADS)

José Andrés, Luis; Menéndez, María Fe; Gómez, David; Martínez, Ana Luisa; Bristow, Noel; Kettle, Jeffrey Paul; Menéndez, Armando; Ruiz, Bernardino

2015-07-01

Rapid synthesis of ultralong silver nanowires (AgNWs) has been obtained using a one-pot polyol-mediated synthetic procedure. The AgNWs have been prepared from the base materials in less than one hour with nanowire lengths reaching 195 μm, which represents the quickest synthesis and one of the highest reported aspect ratios to date. These results have been achieved through a joint analysis of all reaction parameters, which represents a clear progress beyond the state of the art. Dispersions of the AgNWs have been used to prepare thin, flexible, transparent and conducting films using spray coating. Due to the higher aspect ratio, an improved electrical percolation network is observed. This allows a low sheet resistance (RS = 20.2 Ω/sq), whilst maintaining high optical film transparency (T = 94.7%), driving to the highest reported figure-of-merit (FoM = 338). Owing to the light-scattering influence of the AgNWs, the density of the AgNW network can also be varied to enable controllability of the optical haze through the sample. Based on the identification of the optimal haze value, organic photovoltaics (OPVs) have been fabricated using the AgNWs as the transparent electrode and have been benchmarked against indium tin oxide (ITO) electrodes. Overall, the performance of OPVs made using AgNWs sees a small decrease in power conversion efficiency (PCE), primarily due to a fall in open-circuit voltage (50 mV). This work indicates that AgNWs can provide a low cost, rapid and roll-to-roll compatible alternative to ITO in OPVs, with only a small compromise in PCE needed.

Fully solution-processing route toward highly transparent polymer solar cells.

PubMed

Guo, Fei; Kubis, Peter; Stubhan, Tobias; Li, Ning; Baran, Derya; Przybilla, Thomas; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J

2014-10-22

We report highly transparent polymer solar cells using metallic silver nanowires (AgNWs) as both the electron- and hole-collecting electrodes. The entire stack of the devices is processed from solution using a doctor blading technique. A thin layer of zinc oxide nanoparticles is introduced between photoactive layer and top AgNW electrode which plays decisive roles in device functionality: it serves as a mechanical foundation which allows the solution-deposition of top AgNWs, and more importantly it facilitates charge carriers extraction due to the better energy level alignment and the formation of ohmic contacts between the active layer/ZnO and ZnO/AgNWs. The resulting semitransparent polymer:fullerene solar cells showed a power conversion efficiency of 2.9%, which is 72% of the efficiency of an opaque reference device. Moreover, an average transmittance of 41% in the wavelength range of 400-800 nm is achieved, which is of particular interest for applications in transparent architectures.

Carbon Nanotube Networks Reinforced by Silver Nanowires with Improved Optical Transparency and Conductivity

NASA Astrophysics Data System (ADS)

Martine, Patricia; Fakhimi, Azin; Lin, Ling; Jurewicz, Izabela; Dalton, Alan; Zakhidov, Anvar A.; Baughman, Ray H.

2015-03-01

We have fabricated highly transparent and conductive free-standing nanocomposite thin film electrodes by adding silver nanowires (AgNWs) to dry-spun Multiwall Carbon Nanotube (MWNT) aerogels. This nanocomposite exhibits desirable properties such as high optical transmittance, excellent flexibility and enhanced electrical conductivity. The incorporation of the AgNWs to the MWNT aerogels was accomplished by using a spray coating method. The optical transparency and sheet resistance of the nanocomposite was tuned by adjusting the concentration of AgNWs, back pressure and nozzle distance of the spray gun to the MWNT aerogel during deposition. As the solvent evaporated, the aerogel MWNT bundles densified via surface tension which caused the MWNT bundles to collapse. This adjustable process was responsible in forming well defined apertures that increased the nanocomposite's transmittance up to 90 percent. Via AgNWs percolation and random interconnections between separate MWNT bundles in the aerogel matrix, the sheet resistance decreased from 1 K ohm/sq to less than 100 ohm/sq. Alan G. MacDiarmid NanoTech Institute

Understanding the mechanisms leading to failure in metallic nanowire-based transparent heaters, and solution for stability enhancement

NASA Astrophysics Data System (ADS)

Lagrange, M.; Sannicolo, T.; Muñoz-Rojas, D.; Guillo Lohan, B.; Khan, A.; Anikin, M.; Jiménez, C.; Bruckert, F.; Bréchet, Y.; Bellet, D.

2017-02-01

Silver nanowire (AgNW) networks are emerging as one of the most promising alternatives to indium tin oxide (ITO) for transparent electrodes in flexible electronic devices. They can be used in a variety of optoelectronic applications such as solar cells, touch panels and organic light-emitting diodes. Recently they have also proven to be very efficient when used as transparent heaters (THs). In addition to the study of AgNW networks acting as THs in regular use, i.e. at low voltage and moderate temperature, their stability and physical behavior at higher voltages and for longer durations should be studied in view of their integration into real devices. The properties of AgNW networks deposited by spray coating on glass or flexible transparent substrates are thoroughly studied via in situ measurements. The AgNW networks’ behavior at different voltages for different durations and under different atmospheric conditions, both in air and under vacuum, has been examined. At low voltage, a reversible electrical response is observed while irreversibility and even failure are observed at higher voltages. In order to gain a deeper insight into the behavior of AgNW networks used as THs, simple but realistic physical models are proposed and are found to be in fair agreement with the experimental data. Finally, as the stability of AgNW networks is a key issue, we demonstrate that coating AgNW networks with a very thin layer of TiO2 using atomic layer deposition (ALD) improves the material’s resistance against electrical and thermal instabilities without altering optical transmittance. We show that the critical annealing temperature associated to network breakdown increases from 270 °C for the as-deposited AgNW networks to 420 °C for AgNW networks coated with TiO2. Similarly, the electrical failure which occurs at 7 V for the as-deposited networks increases to 13 V for TiO2-coated networks. TiO2 is also proved to stabilize AgNW networks during long duration operation and at

Aligned silver nanowire-based transparent electrodes for engineering polarisation-selective optoelectronics.

PubMed

Park, Byoungchoo; Bae, In-Gon; Huh, Yoon Ho

2016-01-18

We herein report on a remarkably simple, fast, and economic way of fabricating homogeneous and well oriented silver nanowires (AgNWs) that exhibit strong in-plane electrical and optical anisotropies. Using a small quantity of AgNW suspension, the horizontal-dip (H-dip) coating method was applied, in which highly oriented AgNWs were deposited unidirectionally along the direction of coating over centimetre-scale lengths very rapidly. In applying the H-dip-coating method, we adjusted the shear strain rate of the capillary flow in the Landau-Levich meniscus of the AgNW suspension, which induced a high degree of uniaxial orientational ordering (0.37-0.43) of the AgNWs, comparable with the ordering seen in archetypal nematic liquid crystal (LC) materials. These AgNWs could be used to fabricate not only transparent electrodes, but also LC-alignment electrodes for LC devices and/or polarising electrodes for organic photovoltaic devices, having the potential to revolutionise the architectures of a number of polarisation-selective opto-electronic devices for use in printed/organic electronics.

The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes

PubMed Central

Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S.; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

2016-01-01

This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs. PMID:27387274

The role of graphene formed on silver nanowire transparent conductive electrode in ultra-violet light emitting diodes

NASA Astrophysics Data System (ADS)

Seo, Tae Hoon; Lee, Seula; Min, Kyung Hyun; Chandramohan, S.; Park, Ah Hyun; Lee, Gun Hee; Park, Min; Suh, Eun-Kyung; Kim, Myung Jong

2016-07-01

This paper reports a highly reliable transparent conductive electrode (TCE) that integrates silver nanowires (AgNWs) and high-quality graphene as a protecting layer. Graphene with minimized defects and large graphene domains has been successfully obtained through a facile two-step growth approach. Ultraviolet light emitting diodes (UV-LEDs) were fabricated with AgNWs or hybrid electrodes where AgNWs were combined with two-step grown graphene (A-2GE) or conventional one-step grown graphene (A-1GE). The device performance and reliability of the UV-LEDs with three different electrodes were compared. The A-2GE offered high figure of merit owing to the excellent UV transmittance and reduced sheet resistance. As a consequence, the UV-LEDs made with A-2GE demonstrated reduced forward voltage, enhanced electroluminescence (EL) intensity, and alleviated efficiency droop. The effects of joule heating and UV light illumination on the electrode stability were also studied. The present findings prove superior performance of the A-2GE under high current injection and continuous operation of UV LED, compared to other electrodes. From our observation, the A-2GE would be a reliable TCE for high power UV-LEDs.

Improved Performance by SiO2 Hollow Nanospheres for Silver Nanowire-Based Flexible Transparent Conductive Films.

PubMed

Zhang, Liwen; Zhang, Longjiang; Qiu, Yejun; Ji, Yang; Liu, Ya; Liu, Hong; Li, Guangji; Guo, Qiuquan

2016-10-12

Flexible transparent conductive films (TCFs) have attracted tremendous interest thanks to the rapid development of portable/flexible/wearable electronics. TCFs on the basis of silver nanowires (AgNWs) with excellent performance are becoming an efficient alternative to replace the brittle transparent metal oxide. In this study, a promising method was developed by introducing SiO 2 hollow nanospheres (SiO 2 -HNSs) into the film to significantly improve the performance of AgNW-based TCFs. Since SiO 2 -HNSs have opposite charges to AgNWs, the strong attraction had promoted a uniform distribution of AgNWs and made the distance between AgNWs closer, which could decrease the contact resistance greatly. The introduction of SiO 2 layer remarkably enhanced the transmission of visible light and the conductivity. In addition, the TCFs constructed by AgNWs and SiO 2 -HNSs showed much higher thermal stability and adhesive force than those by only AgNWs. As an example, the transmission of AgNW/SiO 2 -HNS-coated poly(ethylene terephthalate) (PET) could increase about 14.3% in comparison to AgNW-coated PET. Typically, a AgNW/SiO 2 -HNS-based TCF with a sheet resistance of about 33 Ω/sq and transmittance of about 98.0% (excluding substrate) could be obtained with excellent flexibility, adhesion, and thermal stability. At last some devices were fabricated.

Ultrasmooth, extremely deformable and shape recoverable Ag nanowire embedded transparent electrode

PubMed Central

Nam, Sanggil; Song, Myungkwan; Kim, Dong-Ho; Cho, Byungjin; Lee, Hye Moon; Kwon, Jung-Dae; Park, Sung-Gyu; Nam, Kee-Seok; Jeong, Yongsoo; Kwon, Se-Hun; Park, Yun Chang; Jin, Sung-Ho; Kang, Jae-Wook; Jo, Sungjin; Kim, Chang Su

2014-01-01

Transparent electrodes have been widely used in electronic devices such as solar cells, displays, and touch screens. Highly flexible transparent electrodes are especially desired for the development of next generation flexible electronic devices. Although indium tin oxide (ITO) is the most commonly used material for the fabrication of transparent electrodes, its brittleness and growing cost limit its utility for flexible electronic devices. Therefore, the need for new transparent conductive materials with superior mechanical properties is clear and urgent. Ag nanowire (AgNW) has been attracting increasing attention because of its effective combination of electrical and optical properties. However, it still suffers from several drawbacks, including large surface roughness, instability against oxidation and moisture, and poor adhesion to substrates. These issues need to be addressed before wide spread use of metallic NW as transparent electrodes can be realized. In this study, we demonstrated the fabrication of a flexible transparent electrode with superior mechanical, electrical and optical properties by embedding a AgNW film into a transparent polymer matrix. This technique can produce electrodes with an ultrasmooth and extremely deformable transparent electrode that have sheet resistance and transmittance comparable to those of an ITO electrode. PMID:24763248

Ultrasmooth, extremely deformable and shape recoverable Ag nanowire embedded transparent electrode.

PubMed

Nam, Sanggil; Song, Myungkwan; Kim, Dong-Ho; Cho, Byungjin; Lee, Hye Moon; Kwon, Jung-Dae; Park, Sung-Gyu; Nam, Kee-Seok; Jeong, Yongsoo; Kwon, Se-Hun; Park, Yun Chang; Jin, Sung-Ho; Kang, Jae-Wook; Jo, Sungjin; Kim, Chang Su

2014-04-25

Transparent electrodes have been widely used in electronic devices such as solar cells, displays, and touch screens. Highly flexible transparent electrodes are especially desired for the development of next generation flexible electronic devices. Although indium tin oxide (ITO) is the most commonly used material for the fabrication of transparent electrodes, its brittleness and growing cost limit its utility for flexible electronic devices. Therefore, the need for new transparent conductive materials with superior mechanical properties is clear and urgent. Ag nanowire (AgNW) has been attracting increasing attention because of its effective combination of electrical and optical properties. However, it still suffers from several drawbacks, including large surface roughness, instability against oxidation and moisture, and poor adhesion to substrates. These issues need to be addressed before wide spread use of metallic NW as transparent electrodes can be realized. In this study, we demonstrated the fabrication of a flexible transparent electrode with superior mechanical, electrical and optical properties by embedding a AgNW film into a transparent polymer matrix. This technique can produce electrodes with an ultrasmooth and extremely deformable transparent electrode that have sheet resistance and transmittance comparable to those of an ITO electrode.

Highly efficient flexible optoelectronic devices using metal nanowire-conducting polymer composite transparent electrode

NASA Astrophysics Data System (ADS)

Jung, Eui Dae; Nam, Yun Seok; Seo, Houn; Lee, Bo Ram; Yu, Jae Choul; Lee, Sang Yun; Kim, Ju-Young; Park, Jang-Ung; Song, Myoung Hoon

2015-09-01

Here, we report a comprehensive analysis of the electrical, optical, mechanical, and surface morphological properties of composite nanostrutures based on silver nanowires (AgNW) and PEDOT:PSS conducting polymer for the use as flexible and transparent electrodes. Compared to ITO or the single material of AgNW or PEDOT:PSS, the AgNW/PEDOT:PSS composite electrode showed high electrical conductivity with a low sheet resistance of 26.8 Ω/sq at 91% transmittance (at 550 nm), improves surface smoothness, and enhances mechanical properties assisted by an amphiphilic fluoro-surfactant. The polymeric light-emitting diodes (PLEDs) and organic solar cells (OSCs) using the AgNW/PEDOT:PSS composite electrode showed higher device performances than those with AgNW and PEDOT:PSS electrodes and excellent flexibility under bending test. These results indicates that the AgNW/PEDOT:PSS composite presented is a good candidate as next-generation transparent elelctrodes for applications into flexible optoelectronic devices. [Figure not available: see fulltext.

An Implantable Transparent Conductive Film with Water Resistance and Ultrabendability for Electronic Devices.

PubMed

Song, Youngjun; Kim, Sejung; Heller, Michael J

2017-12-06

Recently, instead of indium tin oxide, the random mesh pattern of metallic nanowires for flexible transparent conducting electrodes (FTCEs) has received a great amount of interest due to its flexibility, low resistance, reasonable price, and compliant processes. Mostly, nanowires for FTCEs are fabricated by spray or mayer coating methods. However, the metallic nanowire layer of FTCEs, which is fabricated by these methods, has a spiked surface roughness and low junction contact between the nanowires that lead to their high sheet resistance value. Also, the nanowires on FTCEs are easy to peel-off through exterior forces such as bending, twisting, or contact. To solve these problems, we demonstrate novel methods through which silver nanowires (AgNWs) are deposited onto a nanosize porous nitrocellulose (NC) substrate by electrophoretic deposition (EPD) and an opaque and porous substrate. Respectively, through dimethyl sulfoxide treatment, AgNWs on NC (AgNW/NC) is changed to the transparent and nonporous FTCEs. This enhances the junction contact of the AgNWs by EPD and also allows a permanent attachment of AgNWs onto the substrate. To show the mechanical strength of the AgNWs on the transparent nitrocellulose (AgNW/TNC), it is tested by applying diverse mechanical stress, such as a binding test (3M peel-off), compressing, bending, twisting, and folding. Next, we demonstrate that AgNW/TNC can be effectively implanted onto normal newspapers and papers. As paper electronics, light-emitting diodes, which are laminated onto paper, are successfully operated through a basic AgNW/TNC strip circuit. Finally, it is demonstrated that AgNW/TNC and AgNW/TNC on paper are water resistant for 15 min due to the insulation properties of the nonporous substrate.

Flexible Transparent Supercapacitors Based on Hierarchical Nanocomposite Films.

PubMed

Chen, Fanhong; Wan, Pengbo; Xu, Haijun; Sun, Xiaoming

2017-05-31

Flexible transparent electronic devices have recently gained immense popularity in smart wearable electronics and touch screen devices, which accelerates the development of the portable power sources with reliable flexibility, robust transparency and integration to couple these electronic devices. For potentially coupled as energy storage modules in various flexible, transparent and portable electronics, the flexible transparent supercapacitors are developed and assembled from hierarchical nanocomposite films of reduced graphene oxide (rGO) and aligned polyaniline (PANI) nanoarrays upon their synergistic advantages. The nanocomposite films are fabricated from in situ PANI nanoarrays preparation in a blended solution of aniline monomers and rGO onto the flexible, transparent, and stably conducting film (FTCF) substrate, which is obtained by coating silver nanowires (Ag NWs) layer with Meyer rod and then coating of rGO layer on polyethylene terephthalate (PET) substrate. Optimization of the transparency, the specific capacitance, and the flexibility resulted in the obtained all-solid state nanocomposite supercapacitors exhibiting enhanced capacitance performance, good cycling stability, excellent flexibility, and superior transparency. It provides promising application prospects for exploiting flexible, low-cost, transparent, and high-performance energy storage devices to be coupled into various flexible, transparent, and wearable electronic devices.

A dual-scale metal nanowire network transparent conductor for highly efficient and flexible organic light emitting diodes.

PubMed

Lee, Jinhwan; An, Kunsik; Won, Phillip; Ka, Yoonseok; Hwang, Hyejin; Moon, Hyunjin; Kwon, Yongwon; Hong, Sukjoon; Kim, Changsoon; Lee, Changhee; Ko, Seung Hwan

2017-02-02

Although solution processed metal nanowire (NW) percolation networks are a strong candidate to replace commercial indium tin oxide, their performance is limited in thin film device applications due to reduced effective electrical areas arising from the dimple structure and percolative voids that single size metal NW percolation networks inevitably possess. Here, we present a transparent electrode based on a dual-scale silver nanowire (AgNW) percolation network embedded in a flexible substrate to demonstrate a significant enhancement in the effective electrical area by filling the large percolative voids present in a long/thick AgNW network with short/thin AgNWs. As a proof of concept, the performance enhancement of a flexible phosphorescent OLED is demonstrated with the dual-scale AgNW percolation network compared to the previous mono-scale AgNWs. Moreover, we report that mechanical and oxidative robustness, which are critical for flexible OLEDs, are greatly increased by embedding the dual-scale AgNW network in a resin layer.

High conductive and scalable Ag nanowires flexible transparent electrode by nanowelding with physical methods

NASA Astrophysics Data System (ADS)

He, W. W.; Yan, X. H.; Long, Y. F.; Liang, Y. M.; Pan, C.; Zhao, J. L.; Liu, Q. X.

2017-09-01

Transparent electrodes (TEs) are very important for electronic devices. At present, ITO is gaining the largest market share but will be reduced. Ag nanowires (AgNWs) TEs is acknowledged as one of the most potential alternative to ITO. However, AgNWs TEs still have electrical problems because of the low contact between the AgNWs. In this paper, we report three physics methods to increase the conductivity of AgNWs TEs by nanowelding the contact of nanowires. For heat-resistant materials, 200 °C heat-nanowelding can help to reduce the sheet resistance by 96.7%. For pressure resistant materials, 20MPa pressure-nanowelding can help to increase the conductivity by 98.7%. And the transmittance (>90%) remains constant during the above process. Yet, both of these methods cannot improve the adhesion between nanowires and the substrates. Luckily, tight adhesion can be obtained by overcoating a PEDOT: PSS lalyer on AgNWs film which can reduce the sheet resistance by 87.8%. This means that things are usually not perfect, and they have their own advantages and lay the foundation for the popularization and application of AgNWs TEs. In a word, these three nano-welding methods are all suit for manufacture on a large scale for high conductive AgNWs TEs.

Charge Carrier Transport Through the Interface Between Hybrid Electrodes and Organic Materials in Flexible Organic Light Emitting Diodes.

PubMed

Zhou, Huanyu; Cheong, Hahn-Gil; Park, Jin-Woo

2016-05-01

We investigated the electronic properties of composite-type hybrid transparent conductive electrodes (h-TCEs) based on Ag nanowire networks (AgNWs) and indium tin oxide (ITO). These h-TCEs were developed to replace ITO, and their mechanical flexibility is superior to that of ITO. However, the characteristics of charge carriers and the mechanism of charge-carrier transport through the interface between the h-TCE and an organic material are not well understood when the h-TCE is used as the anode in a flexible organic light-emitting diode (f-OLED). AgNWs were spin coated onto polymer substrates, and ITO was sputtered atop the AgNWs. The electronic energy structures of h-TCEs were investigated by ultraviolet photoelectron spectroscopy. f-OLEDs were fabricated on both h-TCEs and ITO for comparison. The chemical bond formation at the interface between the h-TCE and the organic layer in f-OLEDs was investigated by X-ray photoelectron spectroscopy. The performances of f-OLEDs were compared based on the analysis results.

1.4 µm-Thick Transparent Radio Frequency Transmission Lines Based on Instant Fusion of Polyethylene Terephthalate Through Surface of Ag Nanowires

NASA Astrophysics Data System (ADS)

Kim, Sang-Woo; Kim, Kwang-Seok; Park, Myeongkoo; Nah, Wansoo; Kim, Dae Up; Lee, Cheul-Ro; Jung, Seung-Boo; Kim, Jong-Woong

2018-05-01

Though a percolated network of silver nanowires (AgNWs) has been considered the most promising flexible transparent electrode because of it high conductivity, high transmittance, and excellent flexibility, fabrication of AgNW-based transmission lines designed to conduct high frequency signals has been scarcely reported. The fabrication and performance of extremely thin (1.4 µm thick) and low lossy (smaller than - 17 dB for reflection coefficient corresponding to 2.5 GHz) transmission lines with unprecedented transparency (higher than 90% for the entire visible light spectrum) are demonstrated in this study. AgNWs deposited onto a 1.4 µm-thick polyethylene terephthalate (PET) sheet were irradiated by intense-pulsed-light to selectively raise their temperature. The intensive photon energy delivered to the AgNWs simultaneously caused the active diffusion of Ag atoms and plasmonic welding, resulting in large drops in resistivity without drastic changes in their physical shape or the optical transmittance of the films. Furthermore, absorption of heat also thermally activated the underlying polymer and causing it to react with the surface of the AgNWs—this results in enhanced adhesion between the AgNWs and the PET. Measurements and simulation of specially designed coplanar waveguide circuits revealed that the fabricated electrode could simultaneously provide excellent transmission characteristics and mechanical stability and transparency.

Improvements in purification of silver nanowires by decantation and fabrication of flexible transparent electrodes. Application to capacitive touch sensors.

PubMed

Mayousse, Céline; Celle, Caroline; Moreau, Eléonore; Mainguet, Jean-François; Carella, Alexandre; Simonato, Jean-Pierre

2013-05-31

Transparent flexible electrodes made of metallic nanowires, and in particular silver nanowires (AgNWs), appear as an extremely promising alternative to transparent conductive oxides for future optoelectronic devices. Though significant progresses have been made the last few years, there is still some room for improvement regarding the synthesis of high quality silver nanowire solutions and fabrication process of high performance electrodes. We show that the commonly used purification process can be greatly simplified through decantation. Using this process it is possible to fabricate flexible electrodes by spray coating with sheet resistance lower than 25 Ω sq⁻¹ at 90% transparency in the visible spectrum. These electrodes were used to fabricate an operative transparent flexible touch screen. To our knowledge this is the first reported AgNW based touch sensor relying on capacitive technology.

Flexible room-temperature formaldehyde sensors based on rGO film and rGo/MoS2 hybrid film

NASA Astrophysics Data System (ADS)

Li, Xian; Wang, Jing; Xie, Dan; Xu, Jianlong; Xia, Yi; Li, Weiwei; Xiang, Lan; Li, Zhemin; Xu, Shiwei; Komarneni, Sridhar

2017-08-01

Gas sensors based on reduced graphene oxide (rGO) films and rGO/MoS2 hybrid films were fabricated on polyethylene naphthalate substrates by a simple self-assembly method, which yielded flexible devices for detection of formaldehyde (HCHO) at room temperature. The sensing test results indicated that the rGO and rGO/MoS2 sensors were highly sensitive and fully recoverable to a ppm-level of HCHO. The bending and fatigue test results revealed that the sensors were also mechanically robust, durable and effective for long-term use. The rGO/MoS2 sensors showed higher sensitivities than rGO sensors, which was attributed to the enhanced HCHO adsorption and electron transfer mediated by MoS2. Furthermore, two kinds of MoS2 nanosheets were prepared by either hydrothermal synthesis or chemical exfoliation and were compared for their detection of HCHO, which revealed that the hydrothermally produced MoS2 nanosheets with rich defects led to enhanced sensitivity of the rGO/MoS2 sensors. Moreover, these fabricated flexible sensors can be applied for the HCHO detection in food packaging.

Flexible room-temperature formaldehyde sensors based on rGO film and rGo/MoS2 hybrid film.

PubMed

Li, Xian; Wang, Jing; Xie, Dan; Xu, Jianlong; Xia, Yi; Li, Weiwei; Xiang, Lan; Li, Zhemin; Xu, Shiwei; Komarneni, Sridhar

2017-08-11

Gas sensors based on reduced graphene oxide (rGO) films and rGO/MoS 2 hybrid films were fabricated on polyethylene naphthalate substrates by a simple self-assembly method, which yielded flexible devices for detection of formaldehyde (HCHO) at room temperature. The sensing test results indicated that the rGO and rGO/MoS 2 sensors were highly sensitive and fully recoverable to a ppm-level of HCHO. The bending and fatigue test results revealed that the sensors were also mechanically robust, durable and effective for long-term use. The rGO/MoS 2 sensors showed higher sensitivities than rGO sensors, which was attributed to the enhanced HCHO adsorption and electron transfer mediated by MoS 2 . Furthermore, two kinds of MoS 2 nanosheets were prepared by either hydrothermal synthesis or chemical exfoliation and were compared for their detection of HCHO, which revealed that the hydrothermally produced MoS 2 nanosheets with rich defects led to enhanced sensitivity of the rGO/MoS 2 sensors. Moreover, these fabricated flexible sensors can be applied for the HCHO detection in food packaging.

Highly transparent and thermal-stable silver nanowire conductive film covered with ZnMgO by atomic-layer-deposition

NASA Astrophysics Data System (ADS)

Wang, Lei; Huang, Dongchen; Li, Min; Xu, Hua; Zou, Jianhua; Tao, Hong; Peng, Junbiao; Xu, Miao

2017-12-01

Solution-processed silver nanowires (AgNWs) have been considered as a promising material for next generation flexible transparent conductive electrodes. However AgNWs films have several intrinsic drawbacks, such as thermal stability and storage stability. Herein, we demonstrate a laminated ZnO/MgO (ZnMgO, ZMO) as a protective layer on the AgNWs films using atomic layer deposition (ALD). The fabricated films exhibited a low sheet resistance of 16 Ω/sq with high transmittance of 91% at 550 nm, an excellent thermal stability and bending property. The ZMO film grows perpendicularly on the surface of the AgNWs, making a perfect coverage of bulk silver nanowires and junction, which can effectively prompt the electrical transport behavior and enhance stability of the silver nanowires network.

Fabrication of silver nanowires and metal oxide composite transparent electrodes and their application in UV light-emitting diodes

NASA Astrophysics Data System (ADS)

Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Wang, Chunliang; Liu, Yichun

2016-08-01

In this paper, we prepared the silver nanowires (AgNWs)/aluminum-doped zinc oxide (AZO) composite transparent conducting electrodes for n-ZnO/p-GaN heterojunction light emitting-diodes (LEDs) by drop casting AgNW networks and subsequent atomic layer deposition (ALD) of AZO at 150 °C. The contact resistances between AgNWs were dramatically reduced by pre-annealing in the vacuum chamber before the ALD of AZO. In this case, AZO works not only as the conformal passivation layer that protects AgNWs from oxidation, but also as the binding material that improves AgNWs adhesion to substrates. Due to the localized surface plasmons (LSPs) of the AgNWs resonant coupling with the ultraviolet (UV) light emission from the LEDs, a higher UV light extracting efficiency is achieved from LEDs with the AgNWs/AZO composite electrodes in comparison with the conventional AZO electrodes. Additionally, the antireflective nature of random AgNW networks in the composite electrodes caused a broad output light angular distribution, which could be of benefit to certain optoelectronic devices like LEDs and solar cells.

Direct Room Temperature Welding and Chemical Protection of Silver Nanowire Thin Films for High Performance Transparent Conductors.

PubMed

Ge, Yongjie; Duan, Xidong; Zhang, Meng; Mei, Lin; Hu, Jiawen; Hu, Wei; Duan, Xiangfeng

2018-01-10

Silver nanowire (Ag-NW) thin films have emerged as a promising next-generation transparent electrode. However, the current Ag-NW thin films are often plagued by high NW-NW contact resistance and poor long-term stability, which can be largely attributed to the ill-defined polyvinylpyrrolidone (PVP) surface ligands and nonideal Ag-PVP-Ag contact at NW-NW junctions. Herein, we report a room temperature direct welding and chemical protection strategy to greatly improve the conductivity and stability of the Ag-NW thin films. Specifically, we use a sodium borohydride (NaBH 4 ) treatment process to thoroughly remove the PVP ligands and produce a clean Ag-Ag interface that allows direct welding of NW-NW junctions at room temperature, thus greatly improving the conductivity of the Ag-NW films, outperforming those obtained by thermal or plasmonic thermal treatment. We further show that, by decorating the as-formed Ag-NW thin film with a dense, hydrophobic dodecanethiol layer, the stability of the Ag-NW film can be greatly improved by 150-times compared with that of PVP-wrapped ones. Our studies demonstrate that a proper surface ligand design can effectively improve the conductivity and stability of Ag-NW thin films, marking an important step toward their applications in electronic and optoelectronic devices.

Hybrid nanostructure heterojunction solar cells fabricated using vertically aligned ZnO nanotubes grown on reduced graphene oxide.

PubMed

Yang, Kaikun; Xu, Congkang; Huang, Liwei; Zou, Lianfeng; Wang, Howard

2011-10-07

Using reduced graphene oxide (rGO) films as the transparent conductive coating, inorganic/organic hybrid nanostructure heterojunction photovoltaic devices have been fabricated through hydrothermal synthesis of vertically aligned ZnO nanorods (ZnO-NRs) and nanotubes (ZnO-NTs) on rGO films followed by the spin casting of a poly(3-hexylthiophene) (P3HT) film. The data show that larger interfacial area in ZnO-NT/P3HT composites improves the exciton dissociation and the higher electrode conductance of rGO films helps the power output. This study offers an alternative to manufacturing nanostructure heterojunction solar cells at low temperatures using potentially low cost materials.

Silver Nanowire Transparent Conductive Electrodes for High-Efficiency III-Nitride Light-Emitting Diodes

PubMed Central

Oh, Munsik; Jin, Won-Yong; Jun Jeong, Hyeon; Jeong, Mun Seok; Kang, Jae-Wook; Kim, Hyunsoo

2015-01-01

Silver nanowires (AgNWs) have been successfully demonstrated to function as next-generation transparent conductive electrodes (TCEs) in organic semiconductor devices owing to their figures of merit, including high optical transmittance, low sheet resistance, flexibility, and low-cost processing. In this article, high-quality, solution-processed AgNWs with an excellent optical transmittance of 96.5% at 450 nm and a low sheet resistance of 11.7 Ω/sq were demonstrated as TCEs in inorganic III-nitride LEDs. The transmission line model applied to the AgNW contact to p-GaN showed that near ohmic contact with a specific contact resistance of ~10−3 Ωcm2 was obtained. The contact resistance had a strong bias-voltage (or current-density) dependence: namely, field-enhanced ohmic contact. LEDs fabricated with AgNW electrodes exhibited a 56% reduction in series resistance, 56.5% brighter output power, a 67.5% reduction in efficiency droop, and a approximately 30% longer current spreading length compared to LEDs fabricated with reference TCEs. In addition to the cost reduction, the observed improvements in device performance suggest that the AgNWs are promising for application as next-generation TCEs, to realise brighter, larger-area, cost-competitive inorganic III-nitride light emitters. PMID:26333768

Highly Transparent and Self-Extinguishing Nanofibrillated Cellulose-Monolayer Clay Nanoplatelet Hybrid Films.

PubMed

Ming, Siyi; Chen, Gang; He, Jiahao; Kuang, Yudi; Liu, Yu; Tao, Ruiqiang; Ning, Honglong; Zhu, Penghui; Liu, Yingyao; Fang, Zhiqiang

2017-08-29

A viable solution toward "green" optoelectronics is rooted in our ability to fabricate optoelectronics on transparent nanofibrillated cellulose (NFC) film substrates. However, the flammability of transparent NFC film poses a severe fire hazard in optoelectronic devices. Despite many efforts toward enhancing the fire-retardant features of transparent NFC film, making NFC film fire-retardant while maintaining its high transparency (≥90%) remains an ambitious objective. Herein, we combine NFC with NFC-dispersed monolayer clay nanoplatelets as a fire retardant to prepare highly transparent NFC-monolayer clay nanoplatelet hybrid films with a superb self-extinguishing behavior. Homogeneous and stable monolayer clay nanoplatelet dispersion was initially obtained by using NFC as a green dispersing agent with the assistance of ultrasonication and then used to blend with NFC to prepare highly transparent and self-extinguishing hybrid films by a water evaporation-induced self-assembly process. As the content of monolayer clay nanoplatelets increased from 5 wt % to 50 wt %, the obtained hybrid films presented enhanced self-extinguishing behavior (limiting oxygen index sharply increased from 21% to 96.5%) while retaining a ∼90% transparency at 600 nm. More significantly, the underlying mechanisms for the high transparency and excellent self-extinguishing behavior of these hybrid films with a clay nanoplatelet content of over 30 wt % were unveiled by a series of characterizations such as SEM, XRD, TGA, and limiting oxygen index tester. This work offers an alternative environmentally friendly, self-extinguishing, and highly transparent substrate to next-generation optoelectronics, and is aimed at providing a viable solution to environmental concerns that are caused by ever-increasing electronic waste.

High-performance Bi-stage process in reduction of graphene oxide for transparent conductive electrodes

NASA Astrophysics Data System (ADS)

Alahbakhshi, Masoud; Fallahi, Afsoon; Mohajerani, Ezeddin; Fathollahi, Mohammad-Reza; Taromi, Faramarz Afshar; Shahinpoor, Mohsen

2017-02-01

A novel and innovative approach to develop reduction of graphene oxide (GO) solution for fabrication of highly and truly transparent conductive electrode (TCE) has been presented. Thanks to outstanding mechanical and electronic properties of graphene which offer practical applications in synthesizing composites as well as fabricating various optoelectronic devices, in this study, conductive reduced graphene oxide (r-GO) thin films were prepared through sequential chemical and thermal reduction process of homogeneously dispersed GO solutions. The conductivity and transparency of r-GO thin film is regulated using hydroiodic acid (HI) as reducing agent following by vacuum thermal annealing. The prepared r-GO is characterized by XRD, AFM, UV-vis and Raman spectroscopy. the AFM topographic images reveal surface roughness almost ∼11 nm which became less than 2 nm for the 4 mg/mL solution. Moreover, XRD analysis and Raman spectra substantiate the interlayer spacing between rGO layers has been reduced dramatically and also electronic conjugation has been ameliorated after using HI chemical agent and 700 °C thermal annealing sequentially. Subsequently providing r-GO transparent electrode with decent and satisfactory transparency, acceptable conductivity and suitable work function, it has been exploited as the anode in organic light emitting diode (OLED). The maximum luminance efficiency and maximum power efficiency reached 4.2 cd/A and 0.83 lm/W, respectively. We believe that by optimizing the hole density, sheet resistance, transparency and surface morphology of the r-GO anodes, the device efficiencies can be remarkably increased further.

Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells.

PubMed

Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

2016-03-28

We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ∼80% at 550 nm and sheet resistance of 18 Ω sq(-1). Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.

Cellulose nanofibers/reduced graphene oxide flexible transparent conductive paper.

PubMed

Gao, Kezheng; Shao, Ziqiang; Wu, Xue; Wang, Xi; Li, Jia; Zhang, Yunhua; Wang, Wenjun; Wang, Feijun

2013-08-14

The cellulose nanofibers (CNFs) paper exhibit high visible light transmittance, high mechanical strength, and excellent flexibility. Therefore, CNFs paper may be an excellent substrate material for flexible transparent electronic devices. In this paper, we endeavor to prepare CNFs-based flexible transparent conductive paper by layer-by-layer (LbL) assembly using divalent copper ions (Cu(2+)) as the crosslinking agent. The thickness of the reduced graphene oxide (RGO) active layer in the CNFs paper can be controlled by the cycle times of the LbL assembly. CNFs/[RGO]20 paper has the sheet resistances of ∼2.5 kΩ/□, and the transmittance of about 76% at a wavelength of 550 nm. Furthermore, CNFs/[RGO]20 paper inherits the excellent mechanical properties of CNFs paper, and the ultimate strength is about 136 MPa. CNFs-based flexible transparent conductive paper also exhibits excellent electrical stability and flexibility. Copyright © 2013. Published by Elsevier Ltd.

Graphene, microscale metallic mesh, and transparent dielectric hybrid structure for excellent transparent electromagnetic interference shielding and absorbing

NASA Astrophysics Data System (ADS)

Lu, Zhengang; Ma, Limin; Tan, Jiubin; Wang, Heyan; Ding, Xuemei

2017-06-01

A high-performance transparent electromagnetic interference (EMI) shielding material based on a graphene/metallic mesh/transparent dielectric (GMTD) hybrid structure is designed and characterized. It consists of stacked graphene and metallic mesh layers, with neighboring layers separated by a quartz-glass substrsate. The GMTD hybrid structure combines the microwave-reflecting characteristics of the metallic mesh and the microwave-absorbing characteristics of graphene to achieve simultaneously high visible transmittance, strong microwave shielding effectiveness (SE), and low microwave reflection. Experiments show that a double-graphene and double-metallic mesh GMTD hybrid structure with a mesh periodicity of 160 µm provides microwave SE exceeding 47.79 dB in the K u-band, and an SE exceeding 32.12 dB in the K a-band, with a maximum value of 37.78 dB at 26.5 GHz. SE by absorption exceeds 30.78 dB in the K a-band, with a maximum value of 34.55 dB at 26.5 GHz, while maintaining a normalized visible transmittance of ~85% at 700 nm. This remarkable performance favors the application of the proposed structure as a transparent microwave shield and absorber, and offers a new strategy for transparent EMI shielding.

Two-dimensional hybrid materials: MoS2-RGO nanocomposites enhanced the barrier properties of epoxy coating

NASA Astrophysics Data System (ADS)

Chen, Chunlin; He, Yi; Xiao, Guoqing; Xia, Yunqin; Li, Hongjie; He, Ze

2018-06-01

By the way of hydrothermal reaction, the MoS2 nanoparticles were loaded on the surface of GO sheets uniformly. Then, the MoS2-RGO composites were modified with γ-(2,3-epoxypropoxy)propytrimethoxysilane (KH560), and followed by preparing the MoS2-RGO/epoxy composite coatings. The morphology and structure of MoS2-RGO were characterized though SEM, TEM, FT-IR and XPS. Besides, the corrosion resistance properties of the as-prepared MoS2-RGO/epoxy composite coatings were characterized by means of electrochemical impedance spectroscopy (EIS) and polarization curves analysis, and then the thermal stability and water permeability resistance of coatings were characterized. The results showed that the MoS2 could be loaded on the surface of GO uniformly when the ratio between MoS2 and GO is 1:1. The anti-corrosion property and permeability resistance of the MoS2-RGO/epoxy composites coating was enhanced significantly due to its excellent barrier property. Besides, the thermal property analysis exhibits that the lamellar structure of MoS2, GO and MoS2-RGO can effectively block the escape of the pyrolysis products, resulting in the maximum thermal weightlessness reduced.

Spontaneous and Selective Nanowelding of Silver Nanowires by Electrochemical Ostwald Ripening and High Electrostatic Potential at the Junctions for High-Performance Stretchable Transparent Electrodes.

PubMed

Lee, Hyo-Ju; Oh, Semi; Cho, Ki-Yeop; Jeong, Woo-Lim; Lee, Dong-Seon; Park, Seong-Ju

2018-04-25

Metal nanowires have been gaining increasing attention as the most promising stretchable transparent electrodes for emerging field of stretchable optoelectronic devices. Nanowelding technology is a major challenge in the fabrication of metal nanowire networks because the optoelectronic performances of metal nanowire networks are mostly limited by the high junction resistance between nanowires. We demonstrate the spontaneous and selective welding of Ag nanowires (AgNWs) by Ag solders via an electrochemical Ostwald ripening process and high electrostatic potential at the junctions of AgNWs. The AgNWs were welded by depositing Ag nanoparticles (AgNPs) on the conducting substrate and then exposing them to water at room temperature. The AgNPs were spontaneously dissolved in water to form Ag + ions, which were then reduced to single-crystal Ag solders selectively at the junctions of the AgNWs. Hence, the welded AgNWs showed higher optoelectronic and stretchable performance compared to that of as-formed AgNWs. These results indicate that electrochemical Ostwald ripening-based welding can be used as a promising method for high-performance metal nanowire electrodes in various next-generation devices such as stretchable solar cells, stretchable displays, organic light-emitting diodes, and skin sensors.

Simple synthesis of graphene nanocomposites MgO-rGO and Fe2O3-rGO for multifunctional applications

NASA Astrophysics Data System (ADS)

Abdel-Aal, Seham K.; Ionov, Andrey; Mozhchil, R. N.; Naqvi, Alim H.

2018-05-01

Hummer's method was used to prepare graphene oxide (GO) by chemical exfoliation of graphite. Simple precipitation method was used for the preparation of hybrid nanocomposites MgO-rGO and Fe2O3-rGO. A 0.3 Molar of corresponding metal nitrate solution and GO solution are used for the preparation process. XRD, FT-IR, and XPS were used to characterize the prepared nanocomposites. The reduction of GO into reduced rGO in the formed nanocomposites was confirmed. Morphological characterization showed the formation of needle-shaped nanocrystals of MgO successfully grown on graphene nanosheet with average crystallite size 8.4 nm. Hematite nanocomposite Fe2O3-rGO forms rod-shaped crystals with average crystallite size 27.5 nm. The saturation magnetization observed for Fe2O3-rGO is less than reported value for the pure Fe2O3 nanoparticles. Thermal properties of as-prepared hybrid nanocomposites MgO-rGO and Fe2O3-rGO showed thermal stability of the prepared nanocomposite over long range of temperature.

A gigantically increased ratio of electrical to thermal conductivity and synergistically enhanced thermoelectric properties in interface-controlled TiO2-RGO nanocomposites.

PubMed

Nam, Woo Hyun; Lim, Young Soo; Kim, Woochul; Seo, Hyeon Kook; Dae, Kyun Seong; Lee, Soonil; Seo, Won-Seon; Lee, Jeong Yong

2017-06-14

We report synergistically enhanced thermoelectric properties through the independently controlled charge and thermal transport properties in a TiO 2 -reduced graphene oxide (RGO) nanocomposite. By the consolidation of TiO 2 -RGO hybrid powder using spark plasma sintering, we prepared an interface-controlled TiO 2 -RGO nanocomposite where its grain boundaries are covered with the RGO network. Both the enhancement in electrical conductivity and the reduction in thermal conductivity were simultaneously achieved thanks to the beneficial effects of the RGO network, and detailed mechanisms are discussed. This led to the gigantic increase in the ratio of electrical to thermal conductivity by six orders of magnitude and also the synergistic enhancement in the thermoelectric figure of merit by two orders. Our results present a strategy for the realization of 'phonon-glass electron-crystals' through interface control using graphene in graphene hybrid thermoelectric materials.

Flash-induced nanowelding of silver nanowire networks for transparent stretchable electrochromic devices.

PubMed

Lee, Chihak; Oh, Youngsu; Yoon, In Seon; Kim, Sun Hong; Ju, Byeong-Kwon; Hong, Jae-Min

2018-02-09

Electrochromic devices (ECDs) are emerging as a novel technology for various applications like commercialized smart window glasses, and auto-dimming rear-view mirrors. Recently, the development of low-power, lightweight, flexible, and stretchable devices has been accelerated to meet the growing demand in the new wearable devices market. Silver nanowires (AgNWs) can become new primary transparent conducting electrode (TCE) materials to replace indium tin oxide (ITO) for ECDs. However, issues such as substrate adhesion, delamination, and higher resistance still exist with AgNWs. Herein, we report a high-performance stretchable flash-induced AgNW-network-based TCE on surface-treated polydimethylsiloxane (PDMS) substrates. A Xe flash light method was used to create nanowelded networks of AgNWs. Surface silane treatments increased the adhesion and durability of the films as well. Finally, ECDs were fabricated under the optimal conditions and examined under strained conditions to demonstrate the resistance and mechanical behaviours of the devices. Results showed a flexible and durable film maintaining a high level of conductivity and reversible resistance behaviour, beyond those currently achievable with standard ITO/PET flexible TCEs.

Preparation of smooth, flexible and stable silver nanowires- polyurethane composite transparent conductive films by transfer method

NASA Astrophysics Data System (ADS)

Bai, Shengchi; Wang, Haifeng; Yang, Hui; Zhang, He; Guo, Xingzhong

2018-02-01

Silver nanowires (AgNWs)-polyurethane (PU) composite transparent conductive films were fabricated via transfer method using AgNWs conductive inks and polyurethane as starting materials, and the effects of post-treatments including heat treatment, NaCl solution bath and HCl solution bath for AgNWs film on the sheet resistance and transmittance of the composite films were respectively investigated in detail. AgNWs networks are uniformly embedded in the PU layer to improve the adhesion and reduce the surface roughness of AgNWs-PU composite films. Heat treatment can melt and weld the nanowires, and NaCl and HCl solution baths promote the dissolution and re-deposition of silver and the dissolving of the polymer, both which form conduction pathways and improve contact of AgNWs for reducing the sheet resistance. Smooth and flexible AgNWs-PU composite film with a transmittance of 85% and a sheet resistance of 15 Ω · sq‑1 is obtained after treated in 0.5 wt% HCl solution bath for 60 s, and the optoelectronic properties of the resultant composite film can maintain after 1000 cycles of bending and 100 days.

High-intensity pulse light sintering of silver nanowire transparent films on polymer substrates: the effect of the thermal properties of substrates on the performance of silver films.

PubMed

Jiu, Jinting; Sugahara, Tohru; Nogi, Masaya; Araki, Teppei; Suganuma, Katsuaki; Uchida, Hiroshi; Shinozaki, Kenji

2013-12-07

Silver nanowire (AgNW) films with a random mesh structure have attracted considerable attention as high-performance flexible transparent electrodes that can replace the expensive and brittle ITO-sputtered films widely used in displays, touch screens, and solar cells. Methods such as heating, pressure treatment, and light treatment are usually used to obtain an optically transparent and electrically conductive film comparable to those of commercial ITO. However, the adhesion between the AgNW film and the substrate is so weak that other overcoatings or extra treatments are necessary. Here, a high-intensity pulsed light (HIPL) sintering technique was developed to rapidly and simply sinter the AgNW film and thus achieve strong adhesion and even high conductivity on these flexible polymer substrates which will be widely applied to the printing of electronic devices. The conductivity of the AgNW film closely depended on the thermal performance of substrates, and the adhesion was determined by the soft state of the substrate surface originating from the glass transition or melting of substrates with light intensity. The rapid sintering technique can be popularized to fabricate new devices on these polymer substrates by considering the thermal properties of the substrate to improve the performance of devices.

Polymer-metal hybrid transparent electrodes for flexible electronics

NASA Astrophysics Data System (ADS)

Kang, Hongkyu; Jung, Suhyun; Jeong, Soyeong; Kim, Geunjin; Lee, Kwanghee

2015-03-01

Despite nearly two decades of research, the absence of ideal flexible and transparent electrodes has been the largest obstacle in realizing flexible and printable electronics for future technologies. Here we report the fabrication of ‘polymer-metal hybrid electrodes’ with high-performance properties, including a bending radius <1 mm, a visible-range transmittance>95% and a sheet resistance <10 Ω sq-1. These features arise from a surface modification of the plastic substrates using an amine-containing nonconjugated polyelectrolyte, which provides ideal metal-nucleation sites with a surface-density on the atomic scale, in combination with the successive deposition of a facile anti-reflective coating using a conducting polymer. The hybrid electrodes are fully functional as universal electrodes for high-end flexible electronic applications, such as polymer solar cells that exhibit a high power conversion efficiency of 10% and polymer light-emitting diodes that can outperform those based on transparent conducting oxides.

Polymer-metal hybrid transparent electrodes for flexible electronics

PubMed Central

Kang, Hongkyu; Jung, Suhyun; Jeong, Soyeong; Kim, Geunjin; Lee, Kwanghee

2015-01-01

Despite nearly two decades of research, the absence of ideal flexible and transparent electrodes has been the largest obstacle in realizing flexible and printable electronics for future technologies. Here we report the fabrication of ‘polymer-metal hybrid electrodes’ with high-performance properties, including a bending radius <1 mm, a visible-range transmittance>95% and a sheet resistance <10 Ω sq−1. These features arise from a surface modification of the plastic substrates using an amine-containing nonconjugated polyelectrolyte, which provides ideal metal-nucleation sites with a surface-density on the atomic scale, in combination with the successive deposition of a facile anti-reflective coating using a conducting polymer. The hybrid electrodes are fully functional as universal electrodes for high-end flexible electronic applications, such as polymer solar cells that exhibit a high power conversion efficiency of 10% and polymer light-emitting diodes that can outperform those based on transparent conducting oxides. PMID:25790133

Transparent and robust siloxane-based hybrid lamella film as a water vapor barrier coating.

PubMed

Tokudome, Yasuaki; Hara, Takaaki; Abe, Risa; Takahashi, Masahide

2014-11-12

Water vapor barriers are important in various application fields, such as food packaging and sealants in electronic devices. Polymer/clay composites are well-studied water vapor barrier materials, but their transparency and mechanical strength degrade with increasing clay loading. Herein, we demonstrate films with good water vapor barrier properties, high transparency, and mechanical/thermal stability. Water vapor barrier films were prepared by the solution crystallization of siloxane hybrid lamellae. The films consist of highly crystallized organic/inorganic hybrid lamellae, which provide high transparency, hardness, and thermal stability and inhibit the permeation of water vapor. The water permeability of a 6 μm thick hybrid film is comparable to that of a 200 μm thick silicon rubber film.

Hydrothermal synthesis of 4ZnO·B2O3·H2O/RGO hybrid material and its flame retardant behavior in flexible PVC and magnesium hydroxide composites

NASA Astrophysics Data System (ADS)

Zhang, Zhifan; Wu, Weihong; Zhang, Mengjiao; Qu, Jiamin; Shi, Lin; Qu, Hongqiang; Xu, Jianzhong

2017-12-01

As a novel and efficient halogen-free composite flame retardant, zinc borate (4ZnO·B2O3·H2O)/reduction graphene oxide (RGO) hybrid material (ZB/RGO) was designed and synthesized using a facile route involving nano-engineering. The unique structure and composition of ZB/RGO were efficaciously confirmed by XRD, FTIR, SEM, TEM, and TG. The incorporation of 7.71 wt% ZB/RGO could significantly enhance the synergistic effect with Mg(OH)2 (MH) when mixed with poly(vinyl chloride) (PVC) as a flame retardant and smoke suppressant, as evaluated by limited oxygen index (LOI), microscale combustion calorimetry (MCC), and a cone calorimetry test (CCT) and compared with PVC, PVC/ZB, PVC/MH, and PVC/ZB/MH blends. The PVC/ZB/RGO/MH formulation could achieve an LOI value of 29.5% (24% higher than neat PVC). More importantly, the heat release rate (HRR), peak heat release rate (PHRR), smoke production rate (SPR), perk smoke production rate (PSPR), total smoke production (TSP), and mass amount loss (MAL) were considerably reduced in CCT, especially the PHRR, TSP, and MAL values for PVC/ZB/RGO/MH blends were reduced to 35%, 34%, and 15%, respectively. This study showed that the design of the novel material might provide a reference for the future development of halogen-free flame retardants consisting of inorganic salt and carbon material, which exhibit excellent flame retardant and smoke suppressant behavior.

An Ag-grid/graphene hybrid structure for large-scale, transparent, flexible heaters.

PubMed

Kang, Junmo; Jang, Yonghee; Kim, Youngsoo; Cho, Seung-Hyun; Suhr, Jonghwan; Hong, Byung Hee; Choi, Jae-Boong; Byun, Doyoung

2015-04-21

Recently, carbon materials such as carbon nanotubes and graphene have been proposed as alternatives to indium tin oxide (ITO) for fabricating transparent conducting materials. However, obtaining low sheet resistance and high transmittance of these carbon materials has been challenging due to the intrinsic properties of the materials. In this paper, we introduce highly transparent and flexible conductive films based on a hybrid structure of graphene and an Ag-grid. Electrohydrodynamic (EHD) jet printing was used to produce a micro-scale grid consisting of Ag lines less than 10 μm wide. We were able to directly write the Ag-grid on a large-area graphene/flexible substrate due to the high conductivity of graphene. The hybrid electrode could be fabricated using hot pressing transfer and EHD jet printing in a non-vacuum, maskless, and low-temperature environment. The hybrid electrode offers an effective and simple route for achieving a sheet resistance as low as ∼4 Ω per square with ∼78% optical transmittance. Finally, we demonstrate that transparent flexible heaters based on the hybrid conductive films could be used in a vehicle or a smart window system.

NiCo2S4 nanorod embedded rGO sheets as electrodes for supercapacitor

NASA Astrophysics Data System (ADS)

Sarkar, Aatreyee; Bera, Supriya; Chakraborty, Amit Kumar

2018-04-01

We report the synthesis of a hybrid nanostructure based on NiCo2S4 and reduced graphene oxide (rGO) following a facile hydrothermal method. X-ray diffraction (XRD), and electron microscopy (FESEM and HRTEM) analyses showed rod-like NiCo2S4 nanostructures embedded in rGO sheets. The electrochemical analysis of the synthesized nanohybrid using cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) revealed specific capacitance of 410 F/gm indicating its suitability as a good electrode material for supercapacitor.

Co(OH)2/RGO/NiO sandwich-structured nanotube arrays with special surface and synergistic effects as high-performance positive electrodes for asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Han; Zhang, Chi; Zhou, Wen; Li, Gao-Ren

2015-10-01

High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (~1470 F g-1 at 5 mV s-1) and excellent cycling stability with ~98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg-1), a high power density (27.5 kW kg-1) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs.High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (~1470 F g-1 at 5 mV s-1) and excellent cycling stability with ~98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and

Nitrogen doped RGO-Co3O4 nanograin cookies: highly porous and robust catalyst for removing nitrophenol from waste water

NASA Astrophysics Data System (ADS)

Pervaiz, Erum; Syam Azhar Virk, Muhammad; Bingxue, Zhang; Yin, Conglin; Yang, Minghui

2017-09-01

The fabrication of nanograins with a uniform morphology wrapped with reduced graphene oxide (RGO) in a designed manner is critical for obtaining a large surface, high porosity and efficient catalytic ability at mild conditions. Hybrid structures of metal oxides decorated on two-dimensional (2D) RGO lacked an interface and channels between the individual grains and RGO. The present work focuses on the synthesis of RGO-wrapped Co3O4 nanograin architecture in micron-sized polyhedrons and the ability to reduce aromatic nitro compounds. Doping N in the designed microstructure polyhedrons resulted in very large surface area (1085.6 m2 g-1) and pore density (0.47 m3 g-1) microcages. Binding energies from x-ray photoelectron spectroscopy (XPS) and Raman intensities confirmed the presence of doped N and RGO-wrapped around Co3O4 nanograins. However, the morphology and microstructure was supported by FESEM and HRTEM images revealing the fabrication of high integrity RGO-Co3O4 microstructure hybrids composed of a 10 nm grain size with narrower grain size distribution. Ammonia treatment produced interconnected channels and dumbbell pores that facilitated ion exchange between the catalyst surface and the liquid medium at the grain boundary interfaces, and offered less mass transport resistance providing fast adsorption of reactants and desorption of the product causing surface renewal. Prepared N-RGO-Co3O4 shows the largest percentage reduction (96%) of p-nitrophenol (p-NP) at room temperature as compared to pure Co3O4 and RGO-Co3O4 nanograin microstructures over 10 min. Fabricated architectures can be applied effectively for fast and facile treatment of industrial waste streams with complex organic molecules.

Preparation of superhydrophobic and transparent micro-nano hybrid coatings from polymethylhydroxysiloxane and silica ormosil aerogels

NASA Astrophysics Data System (ADS)

Nagappan, Saravanan; Park, Jin Joo; Park, Sung Soo; Ha, Chang-Sik

2014-12-01

Superhydrophobic and transparent polymethylhydroxysiloxane (PMHOS)/silica ormosil aerogel hybrids were prepared successfully by mixing of PMHOS with various weight percentages of silica ormosil aerogels (as synthesized from methyltriethoxysilane (MTES) and methyltrimethoxysilane (MTMS) precursors) in separate seal perfume glass vials. The hybrids were spin coated on glass substrate at 1000 rpm for 60 seconds and used for further analysis. The surface morphology and chemical compositions of the hybrids were analyzed by high resolution scanning electron microscopy, high resolution transmission electron microscopy, atomic force spectroscopy, adsorption and desorption isotherm, and X-ray photoelectron spectroscopy. The transparency, thermal decomposition and static contact angle (SCA) of each sample were measured by UV-Visible spectrophotometer, TGA and drop shape analysis system, respectively. The spin coated substrates showed good superhydrophobic properties, thermal stability as well as transparency on the glass substrates.

Strontium eluting graphene hybrid nanoparticles augment osteogenesis in a 3D tissue scaffold

NASA Astrophysics Data System (ADS)

Kumar, Sachin; Chatterjee, Kaushik

2015-01-01

The objective of this work was to prepare hybrid nanoparticles of graphene sheets decorated with strontium metallic nanoparticles and demonstrate their advantages in bone tissue engineering. Strontium-decorated reduced graphene oxide (RGO_Sr) hybrid nanoparticles were synthesized by the facile reduction of graphene oxide and strontium nitrate. X-ray diffraction, transmission electron microscopy, and atomic force microscopy revealed that the hybrid particles were composed of RGO sheets decorated with 200-300 nm metallic strontium particles. Thermal gravimetric analysis further confirmed the composition of the hybrid particles as 22 wt% of strontium. Macroporous tissue scaffolds were prepared by incorporating RGO_Sr particles in poly(ε-caprolactone) (PCL). The PCL/RGO_Sr scaffolds were found to elute strontium ions in aqueous medium. Osteoblast proliferation and differentiation was significantly higher in the PCL scaffolds containing the RGO_Sr particles in contrast to neat PCL and PCL/RGO scaffolds. The increased biological activity can be attributed to the release of strontium ions from the hybrid nanoparticles. This study demonstrates that composites prepared using hybrid nanoparticles that elute strontium ions can be used to prepare multifunctional scaffolds with good mechanical and osteoinductive properties. These findings have important implications for designing the next generation of biomaterials for use in tissue regeneration.The objective of this work was to prepare hybrid nanoparticles of graphene sheets decorated with strontium metallic nanoparticles and demonstrate their advantages in bone tissue engineering. Strontium-decorated reduced graphene oxide (RGO_Sr) hybrid nanoparticles were synthesized by the facile reduction of graphene oxide and strontium nitrate. X-ray diffraction, transmission electron microscopy, and atomic force microscopy revealed that the hybrid particles were composed of RGO sheets decorated with 200-300 nm metallic strontium

Nitrogen doped graphene - Silver nanowire hybrids: An excellent anode material for lithium ion batteries

NASA Astrophysics Data System (ADS)

Nair, Anju K.; Elizabeth, Indu; S, Gopukumar; Thomas, Sabu; M. S, Kala; Kalarikkal, Nandakumar

2018-01-01

We present an in-situ polyol assisted synthesis approach for the preparation of silver nanowires (AgNW) over the nitrogen doped graphene (NG) sheets and has been tested as a viable LIBs anode material for the first time. The use of NG serves as nucleation sites, thereby facilitating the growth of AgNWs. The specific material design of the as-prepared NG-AgNW hybrids involves some advantages, including a continuous AgNW-graphene conducting network. Since AgNWs are electrically conductive, it provides an electrical contact with NG sheets which can effectively help the charge transport process and limit the variations in volume during the lithiation/de-lithiation processes. Apart from this, the insertion of metallic Ag nanowires into a percolated NG network increases the interlayer distance of NG sheets and prevent its restacking. Moreover, the more porous nature of the hybrid structure accommodating the large volume changes of AgNWs. As an anode material for LIBs, the NG-AgNW hybrid displays a remarkable initial discharge capacity of 1215 mAh g-1 and attains a stable capacity of 724 mAh g-1 at a current density of 100 mA g-1 after 50 cycles. The electrode exhibits a stable reversible capacity of 714, 634, 550 and 464 mA h g-1 at 0.1, 0.2, 0.5, 1 Ag-1 respectively. The reversible capacity (710 mAh g-1) at 0.1 Ag-1 is recovered after the cycling at various current densities confirming outstanding rate performance of the material. In addition, the coulombic efficiency, the NG-AgNW anode retains nearly 99% after the second cycle, further indicating its excellent reversibility. The hybrid material exhibits better cycling stability, greater rate capability, capacity retention and superior reversible capacity than that of bare AgNW and NG sheets. Our smart design will pave way for the development of efficient electrode materials for high capacity and long cycle life LIBs.

Fabrication of transparent conductive tri-composite film for electrochromic application

NASA Astrophysics Data System (ADS)

Choi, Dahyun; Lee, Minji; Kim, Hyungsub; Chu, Won-shik; Chun, Doo-man; Ahn, Sung-Hoon; Lee, Caroline Sunyong

2017-12-01

A transparent conductive electrode (TCE) based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was developed using a dry deposition method for application as an electrochromic (EC) device. To improve its electrical conductivity and stable EC performance, AgNW and TiO2 nanoparticles were included in the TCE film. The resulting TiO2/AgNW/PEDOT:PSS hybrid film showed electrical sheet resistivity of 23 Ω/sq., similar to that of a commercial TCE film. When +2.0 V was applied to the hybrid film, the response current was stable, maintaining a value of 2.0 mA. We found that the hybrid film could be used as an EC device, without using commercial TCE film. Antimony-doped tin oxide on indium-doped tin oxide-glass as an ion-storage layer was combined with the hybrid film, with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) injected into the EC device as an ionic liquid electrolyte. The optical transmittance difference between the colored and bleached states was 23% at 630 nm; under applied voltages of -2.0 V and +2.0 V, the coloration efficiency was 127.83 cm2/C. Moreover, cyclic transmittance with switching voltage for 3 h showed stable optical transmittance of 31% at 630 nm. Cyclic voltammetry measurements indicated stable behavior over 50 cycles. Thus, the proposed TCE configuration (TiO2/AgNW/PEDOT:PSS) shows great potential as a substitute for commercial TCEs, the cost of which depends on the availability of rare-earth materials.

New insights into how RGO influences the photocatalytic performance of BiOIO3/RGO nanocomposites under visible and UV irradiation.

PubMed

Xiong, Ting; Dong, Fan; Zhou, Ying; Fu, Min; Ho, Wing-Kei

2015-06-01

Reduced graphene oxide (RGO) has been demonstrated to be effective in enhancing the photocatalytic activity of various semiconductors. However, an important issue that has been overlooked is the role of RGO in UV-induced photocatalysis of RGO-based nanocomposites. In the present work, novel BiOIO3/RGO nanocomposites were prepared by a simple one-pot hydrothermal method, during which BiOIO3 nanoplates were formed in situ on RGO sheets resulting from partial reduction of RGO. The two components of the composite displayed intimate interfacial contact. The as-prepared BiOIO3/RGO nanocomposites exhibited highly enhanced visible photocatalytic activity, relative to that of pure BiOIO3, toward removal of NO from air. However, the BiOIO3/RGO nanocomposites showed only slightly increased photocatalytic activity, relative to pure, under UV irradiation. The limited enhancement of UV activity can be ascribed to the fact that BiOIO3 would be expected to compete with RGO with regard to absorption and utilization of UV light. Evidence shows that RGO can act as a semiconductor rather than a photosensitizer or electron reservoir in BiOIO3/RGO nano-composites. In addition, the active species responsible for photoactivity have been investigated by a DMPO spin-trapping electron spin resonance technique. Photo-generated holes were found to be the main active species inducing the photo-oxidation of NO under visible light, whereas holes and OH radicals are considered to be responsible for photo-activity under UV light. This work points to BiOIO3/RGO nano-composites as new and efficient visible light photocatalysts for environmental remediation applications, and also as a source of new insights into the pivotal role of RGO in photocatalysis of RGO-based nanocomposites under visible as well as UV light. Copyright © 2015 Elsevier Inc. All rights reserved.

Reduced graphene oxide filled poly(dimethyl siloxane) based transparent stretchable, and touch-responsive sensors

NASA Astrophysics Data System (ADS)

Ponnamma, Deepalekshmi; Sadasivuni, Kishor Kumar; Cabibihan, John-John; Yoon, W. Jong; Kumar, Bijandra

2016-04-01

The ongoing revolution in touch panel technology and electronics demands the need for thin films, which are flexible, stretchable, conductive, and highly touch responsive. In this regard, conductive elastomer nanocomposites offer potential solutions for these stipulations; however, viability is limited to the poor dispersion of conductive nanomaterials such as graphene into the matrix. Here, we fabricated a reduced graphene oxide (rGO) and poly(dimethylsiloxane) (PDMS) elastomer based transparent and flexible conductive touch responsive film by dispersing rGO honeycombs uniformly into PDMS elastomer through an ionic liquid (IL) modification. Pursuing a simple, scalable, and safe method of solution casting, this provides a versatile and creative design of a transparent and stretchable rGO/IL-PDMS capacitive touch responsive, where rGO acts as a sensing element. This transparent film with ˜70% transmittance exhibits approximately a five times faster response in comparison to rGO/PDMS film, with negligible degradation over time. The performance of this touch screen film is expected to have applications in the emerging field of foldable electronics.

Reduced graphene oxide filled poly(dimethyl siloxane) based transparent stretchable, and touch-responsive sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponnamma, Deepalekshmi; Sadasivuni, Kishor Kumar; Cabibihan, John-John

The ongoing revolution in touch panel technology and electronics demands the need for thin films, which are flexible, stretchable, conductive, and highly touch responsive. In this regard, conductive elastomer nanocomposites offer potential solutions for these stipulations; however, viability is limited to the poor dispersion of conductive nanomaterials such as graphene into the matrix. Here, we fabricated a reduced graphene oxide (rGO) and poly(dimethylsiloxane) (PDMS) elastomer based transparent and flexible conductive touch responsive film by dispersing rGO honeycombs uniformly into PDMS elastomer through an ionic liquid (IL) modification. Pursuing a simple, scalable, and safe method of solution casting, this provides amore » versatile and creative design of a transparent and stretchable rGO/IL-PDMS capacitive touch responsive, where rGO acts as a sensing element. This transparent film with ∼70% transmittance exhibits approximately a five times faster response in comparison to rGO/PDMS film, with negligible degradation over time. The performance of this touch screen film is expected to have applications in the emerging field of foldable electronics.« less

Rationally-designed configuration of directly-coated Ni 3S 2/Ni electrode by RGO providing superior sodium storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Xiaosheng; Li, Xifei; Bai, Zhimin

Designing nanocomposite materials is an effective approach for enhancing the performance of sodium-ion batteries (SIBs), and understanding the synergy among components is critically important for new, better materials design. Here in this paper, a directly reduced graphene oxide (RGO) decorated anode electrode was designed and tested for SIBs, in which uniform RGO coating onto the Ni 3S 2/Ni electrode was realized using facile hydrothermal reactions. The results indicate that the RGO/Ni 3S 2/Ni electrode delivers a high reversible specific capacity of 448.6 mAh g -1, high capacity retention of 96.5% after 100 cycles, and excellent rate capability of 263.1 mAhmore » g -1 at 800 mA g -1. Compared with the Ni 3S 2/Ni electrode, the improved performance of the RGO/Ni 3S 2/Ni electrode benefits from RGO-promoted displacement reaction of Ni 3S 2 with sodium. DFT calculations reveal that the RGO layer can significantly improve the electron mobility of the RGO/Ni 3S 2 + Na structure, and the hybrid interaction between the extraneous p orbits of C and indigenous p and d orbits of Ni, as well as p orbits of S is the major reason for why RGO can improve the electrical transport properties.« less

Rationally-designed configuration of directly-coated Ni 3S 2/Ni electrode by RGO providing superior sodium storage

DOE PAGES

Song, Xiaosheng; Li, Xifei; Bai, Zhimin; ...

2018-02-28

Designing nanocomposite materials is an effective approach for enhancing the performance of sodium-ion batteries (SIBs), and understanding the synergy among components is critically important for new, better materials design. Here in this paper, a directly reduced graphene oxide (RGO) decorated anode electrode was designed and tested for SIBs, in which uniform RGO coating onto the Ni 3S 2/Ni electrode was realized using facile hydrothermal reactions. The results indicate that the RGO/Ni 3S 2/Ni electrode delivers a high reversible specific capacity of 448.6 mAh g -1, high capacity retention of 96.5% after 100 cycles, and excellent rate capability of 263.1 mAhmore » g -1 at 800 mA g -1. Compared with the Ni 3S 2/Ni electrode, the improved performance of the RGO/Ni 3S 2/Ni electrode benefits from RGO-promoted displacement reaction of Ni 3S 2 with sodium. DFT calculations reveal that the RGO layer can significantly improve the electron mobility of the RGO/Ni 3S 2 + Na structure, and the hybrid interaction between the extraneous p orbits of C and indigenous p and d orbits of Ni, as well as p orbits of S is the major reason for why RGO can improve the electrical transport properties.« less

Nanoscale current spreading analysis in solution-processed graphene oxide/silver nanowire transparent electrodes via conductive atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, Joseph E.; Perumal, Ajay; Bradley, Donal D. C.

2016-05-21

We use conductive atomic force microscopy (CAFM) to study the origin of long-range conductivity in model transparent conductive electrodes composed of networks of reduced graphene oxide (rGO{sub X}) and silver nanowires (AgNWs), with nanoscale spatial resolution. Pristine networks of rGO{sub X} (1–3 monolayers-thick) and AgNWs exhibit sheet resistances of ∼100–1000 kΩ/□ and 100–900 Ω/□, respectively. When the materials are deposited sequentially to form bilayer rGO{sub X}/AgNW electrodes and thermally annealed at 200 °C, the sheet resistance reduces by up to 36% as compared to pristine AgNW networks. CAFM was used to analyze the current spreading in both systems in order to identify themore » nanoscale phenomena responsible for this effect. For rGO{sub X} networks, the low intra-flake conductivity and the inter-flake contact resistance is found to dominate the macroscopic sheet resistance, while for AgNW networks the latter is determined by the density of the inter-AgNW junctions and their associated resistance. In the case of the bilayer rGO{sub X}/AgNWs' networks, rGO{sub X} flakes are found to form conductive “bridges” between AgNWs. We show that these additional nanoscopic electrical connections are responsible for the enhanced macroscopic conductivity of the bilayer rGO{sub X}/AgNW electrodes. Finally, the critical role of thermal annealing on the formation of these nanoscopic connections is discussed.« less

Facile preparation of surfactant-free Au NPs/RGO/Ni foam for degradation of 4-nitrophenol and detection of hydrogen peroxide.

PubMed

Liu, Y Y; Guo, X L; Zhao, L; Zhu, L; Chen, Z T; Chen, J; Zhang, Y; Sun, L T; Zhao, Y H

2018-06-08

The application of Au nanoparticles (Au NPs) often requires surface modification with chemical surfactants, which dramatically reduce the surface activity and increase the chemical contamination and cost of Au NPs. In this research, we have developed a novel Au NPs/reduced graphene oxide/Ni foam hybrid (Au NPs/RGO/NiF) by in situ reduction through ascorbic acid and replacement reaction. This method is green, facile and efficient. The Au NPs are free of chemical surfactants and are homogeneously distributed on the surface of the RGO/NiF. The as-prepared Au NPs/RGO/NiF hybrid is uniform, stable and exhibits not only a high reduction efficiency for the reduction of 4-nitrophenol with a catalytic kinetic constant of up to 0.46 min -1 (0.15 cm 3 catalysis) but also a sensitive and selective detection of H 2 O 2 with a detection limit of ∼1.60 μM.

Facile preparation of surfactant-free Au NPs/RGO/Ni foam for degradation of 4-nitrophenol and detection of hydrogen peroxide

NASA Astrophysics Data System (ADS)

Liu, Y. Y.; Guo, X. L.; Zhao, L.; Zhu, L.; Chen, Z. T.; Chen, J.; Zhang, Y.; Sun, L. T.; Zhao, Y. H.

2018-06-01

The application of Au nanoparticles (Au NPs) often requires surface modification with chemical surfactants, which dramatically reduce the surface activity and increase the chemical contamination and cost of Au NPs. In this research, we have developed a novel Au NPs/reduced graphene oxide/Ni foam hybrid (Au NPs/RGO/NiF) by in situ reduction through ascorbic acid and replacement reaction. This method is green, facile and efficient. The Au NPs are free of chemical surfactants and are homogeneously distributed on the surface of the RGO/NiF. The as-prepared Au NPs/RGO/NiF hybrid is uniform, stable and exhibits not only a high reduction efficiency for the reduction of 4-nitrophenol with a catalytic kinetic constant of up to 0.46 min‑1 (0.15 cm3 catalysis) but also a sensitive and selective detection of H2O2 with a detection limit of ∼1.60 μM.

Thickness-self-controlled synthesis of porous transparent polyaniline-reduced graphene oxide composites towards advanced bifacial dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Wang, Yu-Sheng; Li, Shin-Ming; Hsiao, Sheng-Tsung; Liao, Wei-Hao; Yang, Shin-Yi; Tien, Hsi-Wen; Ma, Chen-Chi M.; Hu, Chi-Chang

2014-08-01

A powerful synthesis strategy is proposed for fabricating porous polyaniline-reduced graphene oxide (PANI-RGO) composites with transparency up to 80% and thickness from 300 to 1000 nm for the counter electrode (CE) of bifacial dye-sensitizing solar cells (DSSCs). The first step is to combine the in-situ positive charge transformation of graphene oxide (GO) through aniline (ANI) prepolymerization and the electrostatic adsorption of ANI oligomer-GO to effectively control the thickness of ultrathin PANI-GO films by adjusting pH of the polymerization media. In the second step, PANI-GO films are reduced with hydroiodic acid to simultaneously enhance the apparent redox activity for the I3-/I- couple and their electronic conductivity. Incorporating the RGO increases the transparency of PANI and facilitates the light-harvesting from the rear side. A DSSC assembled with such a transparent PANI-RGO CE exhibits an excellent efficiency of 7.84%, comparable to 8.19% for a semi-transparent Pt-based DSSC. The high light-harvesting ability of PANI-RGO enhances the efficiency retention between rear- and front-illumination modes to 76.7%, compared with 69.1% for a PANI-based DSSC. The higher retention reduces the power-to-weight ratio and the total cost of bifacial DSSCs, which is also promising in other applications, such as windows, power generators, and panel screens.

Co(OH)2/RGO/NiO sandwich-structured nanotube arrays with special surface and synergistic effects as high-performance positive electrodes for asymmetric supercapacitors.

PubMed

Xu, Han; Zhang, Chi; Zhou, Wen; Li, Gao-Ren

2015-10-28

High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (∼1470 F g(-1) at 5 mV s(-1)) and excellent cycling stability with ∼98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg(-1)), a high power density (27.5 kW kg(-1)) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs.

Silver nanowires-templated metal oxide for broadband Schottky photodetector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Malkeshkumar; Kim, Hong-Sik; Kim, Joondong, E-mail: joonkim@inu.ac.kr

2016-04-04

Silver nanowires (AgNWs)-templated transparent metal oxide layer was applied for Si Schottky junction device, which remarked the record fastest photoresponse of 3.4 μs. Self-operating AgNWs-templated Schottky photodetector showed broad wavelength photodetection with high responsivity (42.4 A W{sup −1}) and detectivity (2.75 × 10{sup 15} Jones). AgNWs-templated indium-tin-oxide (ITO) showed band-to-band excitation due to the internal photoemission, resulting in significant carrier collection performances. Functional metal oxide layer was formed by AgNWs-templated from ITO structure. The grown ITO above AgNWs has a cylindrical shape and acts as a thermal protector of AgNWs for high temperature environment without any deformation. We developed thermal stable AgNWs-templated transparent oxidemore » devices and demonstrated the working mechanism of AgNWs-templated Schottky devices. We may propose the high potential of hybrid transparent layer design for various photoelectric applications, including solar cells.« less

Repercussion of Solid state vs. Liquid state synthesized p-n heterojunction RGO-copper phosphate on proton reduction potential in water.

PubMed

Samal, Alaka; Das, Dipti P; Madras, Giridhar

2018-02-13

The same copper phosphate catalysts were synthesized by obtaining the methods involving solid state as well as liquid state reactions in this work. And then the optimised p-n hybrid junction photocatalysts have been synthesized following the same solid/liquid reaction pathways. The synthesized copper phosphate photocatalyst has unique rod, flower, caramel-treat-like morphology. The Mott-Schottky behavior is in accordance with the expected behavior of n-type semiconductor and the carrier concentration was calculated using the M-S analysis for the photocatalyst. And for the p-n hybrid junction of 8RGO-Cu 3 (PO 4 ) 2 -PA (PA abbreviated for photoassisted synthesis method), 8RGO-Cu 3 (PO 4 ) 2 -EG(EG abbreviated for Ethylene Glycol based synthesis method), 8RGO-Cu 3 (PO 4 ) 2 -PEG (PEG abbreviated for Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol based synthesis method)the amount of H 2 synthesized was 7500, 6500 and 4500 µmol/h/g, respectively. The excited electrons resulting after the irradiation of visible light on the CB of p-type reduced graphene oxide (RGO) migrate easily to n-type Cu 3 (PO 4 ) 2 via. the p-n junction interfaces and hence great charge carrier separation was achieved.

Comparison of impedimetric detection of DNA hybridization on the various biosensors based on modified glassy carbon electrodes with PANHS and nanomaterials of RGO and MWCNTs.

PubMed

Benvidi, Ali; Tezerjani, Marzieh Dehghan; Jahanbani, Shahriar; Mazloum Ardakani, Mohammad; Moshtaghioun, Seyed Mohammad

2016-01-15

In this research, we have developed lable free DNA biosensors based on modified glassy carbon electrodes (GCE) with reduced graphene oxide (RGO) and carbon nanotubes (MWCNTs) for detection of DNA sequences. This paper compares the detection of BRCA1 5382insC mutation using independent glassy carbon electrodes (GCE) modified with RGO and MWCNTs. A probe (BRCA1 5382insC mutation detection (ssDNA)) was then immobilized on the modified electrodes for a specific time. The immobilization of the probe and its hybridization with the target DNA (Complementary DNA) were performed under optimum conditions using different electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed biosensors were used for determination of complementary DNA sequences. The non-modified DNA biosensor (1-pyrenebutyric acid-N- hydroxysuccinimide ester (PANHS)/GCE), revealed a linear relationship between ∆Rct and logarithm of the complementary target DNA concentration ranging from 1.0×10(-16)molL(-1) to 1.0×10(-10)mol L(-1) with a correlation coefficient of 0.992, for DNA biosensors modified with multi-wall carbon nanotubes (MWCNTs) and reduced graphene oxide (RGO) wider linear range and lower detection limit were obtained. For ssDNA/PANHS/MWCNTs/GCE a linear range 1.0×10(-17)mol L(-1)-1.0×10(-10)mol L(-1) with a correlation coefficient of 0.993 and for ssDNA/PANHS/RGO/GCE a linear range from 1.0×10(-18)mol L(-1) to 1.0×10(-10)mol L(-1) with a correlation coefficient of 0.985 were obtained. In addition, the mentioned biosensors were satisfactorily applied for discriminating of complementary sequences from noncomplementary sequences, so the mentioned biosensors can be used for the detection of BRCA1-associated breast cancer. Copyright © 2015. Published by Elsevier B.V.

Transparent and stretchable strain sensors based on metal nanowire microgrids for human motion monitoring

NASA Astrophysics Data System (ADS)

Cho, Ji Hwan; Ha, Sung-Hun; Kim, Jong-Man

2018-04-01

Optical transparency is increasingly considered as one of the most important characteristics required in advanced stretchable strain sensors for application in body-attachable systems. In this paper, we present an entirely solution-processed fabrication route to highly transparent and stretchable resistive strain sensors based on silver nanowire microgrids (AgNW-MGs). The AgNW-MG strain sensors are readily prepared by patterning the AgNWs on a stretchable substrate into a MG geometry via a mesh-template-assisted contact-transfer printing. The MG has a unique architecture comprising the AgNWs and can be stretched to ɛ = 35%, with high gauge factors of ˜6.9 for ɛ = 0%-30% and ˜41.1 for ɛ = 30%-35%. The sensor also shows a high optical transmittance of 77.1% ± 1.5% (at 550 nm) and stably maintains the remarkable optical performance even at high strains. In addition, the sensor responses are found to be highly reversible with negligible hysteresis and are reliable even under repetitive stretching-releasing cycles (1000 cycles at ɛ = 10%). The practicality of the AgNW-MG strain sensor is confirmed by successfully monitoring a wide range of human motions in real time after firmly laminating the device onto various body parts.

Construction of RGO/CdIn2S4/g-C3N4 ternary hybrid with enhanced photocatalytic activity for the degradation of tetracycline hydrochloride

NASA Astrophysics Data System (ADS)

Xiao, Peng; Jiang, Deli; Ju, Lixin; Jing, Junjie; Chen, Min

2018-03-01

Although RGO shows great advantage in promoting charge separation and transfer of semiconductor, construction of an efficient RGO-incorporated photocatalyst is still challenging. Herein, RGO was employed to construct novel RGO/CdIn2S4/g-C3N4 (donated as RGO/CIS/CN) ternary photocatalyst by a facile hydrothermal method for the degradation of tetracycline hydrochloride (TC). The RGO/CIS/CN ternary photocatalyst showed significantly enhanced photocatalytic activity towards the degradation of TC as compared to the binary CIS/CN, CIS/CN, and CN/RGO. The photoluminescence and photocurrent response results indicate that this enhanced photocatalytic activity can be mainly ascribed to the improved charge separation and transfer efficiency. Based on the radical trapping and electron spin resonance results, the superoxide radicals and holes are proposed to play an important role in the degradation of TC over RGO/CIS/CN ternary photocatalyst. This work paves new opportunities for the synthesis of RGO-incorporated ternary photocatalyst as an efficient photocatalyst for the degradation of organic contaminant.

Synthesis of a ternary Ag/RGO/ZnO nanocomposite via microwave irradiation and its application for the degradation of Rhodamine B under visible light.

PubMed

Surendran, Divya Kollikkara; Xavier, Marilyn Mary; Viswanathan, Vandana Parakkal; Mathew, Suresh

2017-06-01

Reduced graphene oxide supporting plasmonic photocatalyst (Ag) on ZnO has been synthesized via a facile two-step microwave synthesis using RGO/ZnO and AgNO 3 . First step involves fabrication of RGO/ZnO via microwave irradiation. The nanocomposites were characterized by X-ray diffraction analysis, transmission electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Ag/RGO/ZnO shows enhanced photoactivity under visible light for the degradation of Rhodamine B. Enhanced charge separation and migration have been assigned using UV-vis diffuse reflectance spectra, photoluminescence spectra, electrochemical impedance spectra, and TCSPC analysis. The improved photoactivity of Ag/RGO/ZnO can be ascribed to the prolonged lifetime of photogenerated electron-hole pairs and effective interfacial hybridization between RGO and Ag with ZnO nanoparticles. Ag nanoparticles can absorb visible light via surface plasmon resonance to enhance photocatalytic activity.

Hard and Transparent Films Formed by Nanocellulose–TiO2 Nanoparticle Hybrids

PubMed Central

Schütz, Christina; Sort, Jordi; Bacsik, Zoltán; Oliynyk, Vitaliy; Pellicer, Eva; Fall, Andreas; Wågberg, Lars; Berglund, Lars; Bergström, Lennart; Salazar-Alvarez, German

2012-01-01

The formation of hybrids of nanofibrillated cellulose and titania nanoparticles in aqueous media has been studied. Their transparency and mechanical behavior have been assessed by spectrophotometry and nanoindentation. The results show that limiting the titania nanoparticle concentration below 16 vol% yields homogeneous hybrids with a very high Young’s modulus and hardness, of up to 44 GPa and 3.4 GPa, respectively, and an optical transmittance above 80%. Electron microscopy shows that higher nanoparticle contents result in agglomeration and an inhomogeneous hybrid nanostructure with a concomitant reduction of hardness and optical transmittance. Infrared spectroscopy suggests that the nanostructure of the hybrids is controlled by electrostatic adsorption of the titania nanoparticles on the negatively charged nanocellulose surfaces. PMID:23049689

An optically transparent, flexible, patterned and conductive silk biopolymer film (Conference Presentation)

NASA Astrophysics Data System (ADS)

Umar, Muhammad; Min, Kyungtaek; Kim, Sunghwan

2017-02-01

Transparent, flexible, and conducting films are of great interest for wearable electronics. For better biotic/abiotic interface, the films to integrate the electronics components requires the patterned surface conductors with optical transparency, smoothness, good electrical conductivity, along with the biofriendly traits of films. We focus on silk fibroin, a natural biopolymer extracted from the Bombyx mori cocoons, for this bioelectronics applications. Here we report an optically transparent, flexible, and patterned surface conductor on a silk film by burying a silver nanowires (AgNW) network below the surface of the silk film. The conducting silk film reveals high optical transparency of 80% and the excellent electronic conductivity of 15 Ω/sq, along with smooth surface. The integration of light emitting diode (LED) chip on the patterned electrodes confirms that the current can flow through the transparent and patterned electrodes on the silk film, and this result shows an application for integration of functional electronic/opto-electronic devices. Additionally, we fabricate a transparent and flexible radio frequency (RF) antenna and resistor on a silk film and apply these as a food sensor by monitoring the increasing resistance by the flow of gases from the spoiled food.

One-pot synthesis of reduced graphene oxide@boron nitride nanosheet hybrids with enhanced oxidation-resistant properties

NASA Astrophysics Data System (ADS)

Sun, Guoxun; Bi, Jianqiang; Wang, Weili; Zhang, Jingde

2017-12-01

Reduced graphene oxide@boron nitride nanosheet (RGO@BNNS) hybrids were prepared for the first time using template-assisted autoclave pyrolysis technique at the temperature as low as 600 °C. The developed method can be scaled into gram-scale synthesis of the material. The BNNSs combine with RGO through van der Waals interplanar interaction without damaging the structures of RGO. Such ultrathin BNNSs on the surface of RGO can serve as high-performance oxidation-resistant coatings in oxidizing atmospheres at high temperatures. The RGO@BNNS hybrids can sustain up to 800 °C over a relatively long period of time.

Welded-Ag-nanowires/FTO conducting film with high transmittance and its application in transparent supercapacitors

NASA Astrophysics Data System (ADS)

Qiao, Zhensong; Yang, Xiaopeng; Liu, Feng; Duan, Guangbin; Cao, Bingqiang

2017-03-01

Silver nanowires (AgNW) with a small diameter were synthesized by a facile and novel polyol reduction method. Ag nanowires ink was then spun on the surface of F-doped SnO2 (FTO) to form the AgNW/FTO conducting film. Welding treatment of the AgNW/FTO conducting film not only increased the optical transmittance from 71.9 % to 79.3 % at 550 nm and decreased the sheet resistance from 11.4 ohm sq-1 to 9.8 ohm sq-1, but also improved the adhesivity of AgNW network on FTO substrate. Furthermore, MnO2 nanosheets were directly deposited on welded-AgNW/FTO (wAF) substrate to prepare a transparent MnO2/weled-AgNW/FTO (MwAF) composite electrode. The MwAF electrode displayed excellent electrochemical performance, including high specific capacitance (375 F g-1 at 5 mV s-1) and superior cycle stability (173.3 % of the initial capacitance after 20000 GCD cycles).

Nanoparticle-Enhanced Silver-Nanowire Plasmonic Electrodes for High-Performance Organic Optoelectronic Devices.

PubMed

Kim, Taehyo; Kang, Saewon; Heo, Jungwoo; Cho, Seungse; Kim, Jae Won; Choe, Ayoung; Walker, Bright; Shanker, Ravi; Ko, Hyunhyub; Kim, Jin Young

2018-05-21

Improved performance in plasmonic organic solar cells (OSCs) and organic light-emitting diodes (OLEDs) via strong plasmon-coupling effects generated by aligned silver nanowire (AgNW) transparent electrodes decorated with core-shell silver-silica nanoparticles (Ag@SiO 2 NPs) is demonstrated. NP-enhanced plasmonic AgNW (Ag@SiO 2 NP-AgNW) electrodes enable substantially enhanced radiative emission and light absorption efficiency due to strong hybridized plasmon coupling between localized surface plasmons (LSPs) and propagating surface plasmon polaritons (SPPs) modes, which leads to improved device performance in organic optoelectronic devices (OODs). The discrete dipole approximation (DDA) calculation of the electric field verifies a strongly enhanced plasmon-coupling effect caused by decorating core-shell Ag@SiO 2 NPs onto the AgNWs. Notably, an electroluminescence efficiency of 25.33 cd A -1 (at 3.2 V) and a power efficiency of 25.14 lm W -1 (3.0 V) in OLEDs, as well as a power conversion efficiency (PCE) value of 9.19% in OSCs are achieved using hybrid Ag@SiO 2 NP-AgNW films. These are the highest values reported to date for optoelectronic devices based on AgNW electrodes. This work provides a new design platform to fabricate high-performance OODs, which can be further explored in various plasmonic and optoelectronic devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Redox reaction between graphene oxide and In powder to prepare In2O3/reduced graphene oxide hybrids for supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Xiaoyang; Wu, Tao; Xia, Fengling; Li, Yi; Zhang, Congcong; Zhang, Lei; Chen, Mingxi; Li, Xichuan; Zhang, Li; Liu, Yu; Gao, Jianping

2014-11-01

A facile and quick route for the chemical reduction of graphene oxide (GO) using In powder as a reductant has been established. The reduction of GO by In powder is traced by UV-visible absorption spectroscopy, and the obtained reduced graphene oxide (rGO) is analyzed. The In3+ ions produced during the reaction between the GO and the In powder are chemically transformed to In2O3 and then form In2O3/rGO hybrids. The In2O3/rGO hybrids are used as electrode materials and their electrochemical performance are studied using cyclic voltammetry and galvanostatic charge/discharge. The In2O3/rGO hybrids demonstrate excellent electrochemical performance and their highest specific capacitance is 178.8 F g-1 which is much higher than that of either In2O3 or rGO. In addition, the In2O3/rGO hybrids are also very stable.

Hybrid display of static image and aerial image by use of transparent acrylic cubes and retro-reflectors

NASA Astrophysics Data System (ADS)

Morita, Shogo; Ito, Shusei; Yamamoto, Hirotsugu

2017-02-01

Aerial display can form transparent floating screen in the mid-air and expected to provide aerial floating signage. We have proposed aerial imaging by retro-reflection (AIRR) to form a large aerial LED screen. However, luminance of aerial image is not sufficiently high so as to be used for signage under broad daylight. The purpose of this paper is to propose a novel aerial display scheme that features hybrid display of two different types of images. Under daylight, signs made of cubes are visible. At night, or under dark lighting situation, aerial LED signs become visible. Our proposed hybrid display is composed of an LED sign, a beam splitter, retro-reflectors, and transparent acrylic cubes. Aerial LED sign is formed with AIRR. Furthermore, we place transparent acrylic cubes on the beam splitter. Light from the LED sign enters transparent acrylic cubes, reflects twice in the transparent acrylic cubes, exit and converge to planesymmetrical position with light source regarding the cube array. Thus, transparent acrylic cubes also form the real image of the source LED sign. Now, we form a sign with the transparent acrylic cubes so that this cube-based sign is apparent under daylight. We have developed a proto-type display by use of 1-cm transparent cubes and retro-reflective sheeting and successfully confirmed aerial image forming with AIRR and transparent cubes as well as cube-based sign under daylight.

Align and random electrospun mat of PEDOT:PSS and PEDOT:PSS/RGO

NASA Astrophysics Data System (ADS)

Sarabi, Ghazale Asghari; Latifi, Masoud; Bagherzadeh, Roohollah

2018-01-01

In this research work we fabricated two ultrafine conductive nanofibrous layers to investigate the materilas composition and their properties for the preparation of supercapacitor materials application. In first layer, a polymer and a conductive polymer were used and second layer was a composition of polymer, conductive polymer and carbon-base material. In both cases align and randomized mat of conductive nanofibers were fabricated using electrospinning set up. Conductive poly (3,4-ethylenedioxythiophene)/ polystyrene sulfonate (PEDOT:PSS) nanofibers were electrospun by dissolving fiber-forming polymer and polyvinyl alcohol (PVA) in an aqueous dispersion of PEDOT:PSS. The effect of addition of reduced graphene oxide (RGO) was considered for nanocomposite layer. The ultrafine conductive polymer fibers and conductive nanocomposite fibrous materials were also fabricated using an electrospinning process. A fixed collector and a rotating drum were used for random and align nanofibers production, respectively. The resulted fibers were characterized and analyzed by SEM, FTIR and two-point probe conductivity test. The average diameter of nanofibers measured by ImageJ software indicated that the average fiber diameter for first layer was 100 nm and for nanocomposite layer was about 85 nm. The presence of PEDOT:PSS and RGO in the nanofibers was confirmed by FT-IR spectroscopy. The conductivity of align and random layers was characterized. The conductivity of PEDOT:PSS nanofibers showed higher enhancement by addition of RGO in aqueous dispersion. The obtained results showed that alignment of fibrous materials can be considered as an engineering tool for tuning the conductivity of fibrous materials for many different applications such as supercapacitors, conductive and transparent materials.

Ultra-thin and smooth transparent electrode for flexible and leakage-free organic light-emitting diodes

PubMed Central

Ok, Ki-Hun; Kim, Jiwan; Park, So-Ra; Kim, Youngmin; Lee, Chan-Jae; Hong, Sung-Jei; Kwak, Min-Gi; Kim, Namsu; Han, Chul Jong; Kim, Jong-Woong

2015-01-01

A smooth, ultra-flexible, and transparent electrode was developed from silver nanowires (AgNWs) embedded in a colorless polyimide (cPI) by utilizing an inverted film-processing method. The resulting AgNW-cPI composite electrode had a transparency of >80%, a low sheet resistance of 8 Ω/□, and ultra-smooth surfaces comparable to glass. Leveraging the robust mechanical properties and flexibility of cPI, the thickness of the composite film was reduced to less than 10 μm, which is conducive to extreme flexibility. This film exhibited mechanical durability, for both outward and inward bending tests, up to a bending radius of 30 μm, while maintaining its electrical performance under cyclic bending (bending radius: 500 μm) for 100,000 iterations. Phosphorescent, blue organic light-emitting diodes (OLEDs) were fabricated using these composites as bottom electrodes (anodes). Hole-injection was poor, because AgNWs were largely buried beneath the composite's surface. Thus, we used a simple plasma treatment to remove the thin cPI layer overlaying the nanowires without introducing other conductive materials. As a result, we were able to finely control the flexible OLEDs' electroluminescent properties using the enlarged conductive pathways. The fabricated flexible devices showed only slight performance reductions of <3% even after repeated foldings with a 30 μm bending radius. PMID:25824143

Novel transparent conductor with enhanced conductivity: hybrid of silver nanowires and dual-doped graphene

NASA Astrophysics Data System (ADS)

Sohn, Hiesang; Woo, Yun Sung; Shin, Weonho; Yun, Dong-Jin; Lee, Taek; Kim, Felix Sunjoo; Hwang, Jinyoung

2017-10-01

We present hybrid transparent conducting films based on silver nanowires (Ag NWs) and doped graphene through novel dual co-doping method by applying various dopants (HNO3 or Au for p-doping and N2H4 for n-doping) on top and bottom sides of graphene. We systematically investigated the effect of dual-doping on their surface as well as electrical and optical properties of graphene and Ag NW/graphene hybrid films through the combination study with various dopant types (p/p, p/n, n/p, and n/n). We found that the p/p-type dual-doped (p-type dopant: HNO3) graphene and its hybrid formation with Ag NWs appeared to be the most effective in enhancing the electrical properties of conductor (doped graphene with ΔR/R0 = 84% and Ag NW/doped graphene hybrid with ΔR/R0 = 62%), demonstrating doped monolayer graphene with high optical transmittance (TT = 97.4%), and sheet resistance (Rs = 188 Ω/sq.). We also note that dual-doping improved such electrical properties without any significant debilitation of optical transparency of conductors (doped graphene with ΔTT = 0.1% and Ag NW/doped graphene hybrid with ΔTT = 0.4%). In addition, the enhanced conductivity of p-type dual-doped graphene allows a hybrid system to form co-percolating network in which Ag NWs can form a secondary conductive path at grain boundaries of polycrystalline graphene.

Porous nickel hydroxide-manganese dioxide-reduced graphene oxide ternary hybrid spheres as excellent supercapacitor electrode materials.

PubMed

Chen, Hao; Zhou, Shuxue; Wu, Limin

2014-06-11

This paper reports the first nickel hydroxide-manganese dioxide-reduced graphene oxide (Ni(OH)2-MnO2-RGO) ternary hybrid sphere powders as supercapacitor electrode materials. Due to the abundant porous nanostructure, relatively high specific surface area, well-defined spherical morphology, and the synergetic effect of Ni(OH)2, MnO2, and RGO, the electrodes with the as-obtained Ni(OH)2-MnO2-RGO ternary hybrid spheres as active materials exhibited significantly enhanced specific capacitance (1985 F·g(-1)) and energy density (54.0 Wh·kg(-1)), based on the total mass of active materials. In addition, the Ni(OH)2-MnO2-RGO hybrid spheres-based asymmetric supercapacitor also showed satisfying energy density and electrochemical cycling stability.

Enhanced photocatalytic performance of RGO/Ag nanocomposites produced via a facile microwave irradiation for the degradation of Rhodamine B in aqueous solution

NASA Astrophysics Data System (ADS)

Divya, K. S.; Chandran, Akash; Reethu, V. N.; Mathew, Suresh

2018-06-01

A series of RGO/Ag nanocomposites with different weight addition ratios of graphene oxide (GO) have been successfully prepared in situ through the simultaneous reduction of GO and AgNO3 via a facile microwave irradiation. X-ray diffraction analysis, Fourier Transform Infrared Spectroscopy, UV-vis diffuse reflectance spectra, Scanning electron microscopy, Photoluminescence spectra, Raman spectra, Atomic Force Microscopy, X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy are employed to determine the properties of the samples. It is found that RGO/Ag nanocomposites with a proper weight addition ratios of GO exhibit higher photocatalytic activity toward liquid phase photodegradation of Rhodamine B under visible light irradiation. The improved photoactivity of RGO/Ag nanocomposites can be ascribed to the integrative synergestic effect of enhanced adsorption capacity, the prolonged lifetime of photogenerated electron-hole pairs and effective interfacial hybridization between RGO and Ag nanoparticles. This study also shows that graphene sheets act as electronic conductive channels to efficiently separate charge carriers from Ag nanoparticles.

Fabrication of ZnAl mixed metal-oxides/RGO nanohybrid composites with enhanced photocatalytic activity under visible light

NASA Astrophysics Data System (ADS)

Ni, Jie; Xue, Jinjuan; Shen, Jing; He, Guangyu; Chen, Haiqun

2018-05-01

The ZnAl mixed metal-oxides (MMOs)/graphene nanocomposites were successfully fabricated by a facile hydrothermal method combined with a calcination process. The thermal treatment enables simultaneously the formation of ZnO/ZnAl2O4 heterogeneous structure, which are uniformly decorated on the surface of graphene, accompanying with the reduction of graphene oxide. The as-prepared heterostructure photocatalysts were well characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectroscopy (DRS) to conduct investigations into the phase structures, microstructure and optical capability. The ZnAl MMO/RGO20 composite displayed favorable adsorption property and photo-degradation efficiency for Ciprofloxacin (CIP) aqueous solution under visible light. The photo-degradation efficiency of the as-prepared ZnAl MMO/RGO20 was 3.0 and even 4.6 times higher than that of ZnAl MMO and pure ZnAl LDH, respectively. The improvement of photocatalytic performance is ascribed to the synergistic effect of heterogeneous structure coupled with graphene, which realizes efficient charge separation efficiency, enlarged visible light adsorption range, and chemical stability of hybrid nanocomposite. The results of EIS, PL and photocurrent response also explained the best performance of ZnAl MMO/RGO20 nanocomposite. Besides, the mechanism of ZnAl MMO/RGO20 photocatalytic system was proposed and analyzed in detail.

Ruthenium based metallopolymer grafted reduced graphene oxide as a new hybrid solar light harvester in polymer solar cells

PubMed Central

Vinoth, R.; Babu, S. Ganesh; Bharti, Vishal; Gupta, V.; Navaneethan, M.; Bhat, S. Venkataprasad; Muthamizhchelvan, C.; Ramamurthy, Praveen C.; Sharma, Chhavi; Aswal, Dinesh K.; Hayakawa, Yasuhiro; Neppolian, B.

2017-01-01

A new class of pyridyl benzimdazole based Ru complex decorated polyaniline assembly (PANI-Ru) was covalently grafted onto reduced graphene oxide sheets (rGO) via covalent functionalization approach. The covalent attachment of PANI-Ru with rGO was confirmed from XPS analysis and Raman spectroscopy. The chemical bonding between PANI-Ru and rGO induced the electron transfer from Ru complex to rGO via backbone of the conjugated PANI chain. The resultant hybrid metallopolymer assembly was successfully demonstrated as an electron donor in bulk heterojunction polymer solar cells (PSCs). A PSC device fabricated with rGO/PANI-Ru showed an utmost ~6 fold and 2 fold enhancement in open circuit potential (Voc) and short circuit current density (Jsc) with respect to the standard device made with PANI-Ru (i.e., without rGO) under the illumination of AM 1.5 G. The excellent electronic properties of rGO significantly improved the electron injection from PANI-Ru to PCBM and in turn the overall performance of the PSC device was enhanced. The ultrafast excited state charge separation and electron transfer role of rGO sheet in hybrid metallopolymer was confirmed from ultrafast spectroscopy measurements. This covalent modification of rGO with metallopolymer assembly may open a new strategy for the development of new hybrid nanomaterials for light harvesting applications. PMID:28225039

Aligned macroporous TiO2/chitosan/reduced graphene oxide (rGO) composites for photocatalytic applications

NASA Astrophysics Data System (ADS)

Chen, Chao; Zhang, Yan; Zeng, Jing; Zhang, Fuqiang; Zhou, Kechao; Bowen, Chris R.; Zhang, Dou

2017-12-01

In this article ice templating is used to fabricate novel TiO2/chitosan/reduced graphene oxide (rGO) composites with a highly aligned macroporous structure for photocatalytic applications. The structure of the composites was readily tailored using the composite composition, for example the lamellar pore width decreased from 50-45 to 5-10 μm, while the lamellar thickness increased from 2-3 to 20-25 μm, with an increase of the TiO2 content from 45 to 77 vol%. Lamellar pore channels between the layers exhibited a more uniform distribution when the rGO content was 1.0 wt%. The increase in viscosity of the composites with high TiO2 contents led to the formation of smaller ice crystals and smaller lamellar pore sizes to enable the production of composite structures with improved mechanical strength. The TiO2/chitosan/rGO composites exhibited excellent photocatalytic degradation of methyl orange and the photocatalytic efficiency was optimized by control of the active material content and microstructure. The hybrid composites with 1.0 wt% rGO showed a degradation percentage of 97%, which makes these novel TiO2/chitosan/rGO freeze cast structures attractive materials as high performance and high strength substrates for photocatalytic degradation applications.

Highly Efficient and Reliable Transparent Electromagnetic Interference Shielding Film.

PubMed

Jia, Li-Chuan; Yan, Ding-Xiang; Liu, Xiaofeng; Ma, Rujun; Wu, Hong-Yuan; Li, Zhong-Ming

2018-04-11

Electromagnetic protection in optoelectronic instruments such as optical windows and electronic displays is challenging because of the essential requirements of a high optical transmittance and an electromagnetic interference (EMI) shielding effectiveness (SE). Herein, we demonstrate the creation of an efficient transparent EMI shielding film that is composed of calcium alginate (CA), silver nanowires (AgNWs), and polyurethane (PU), via a facile and low-cost Mayer-rod coating method. The CA/AgNW/PU film with a high optical transmittance of 92% achieves an EMI SE of 20.7 dB, which meets the requirements for commercial shielding applications. A superior EMI SE of 31.3 dB could be achieved, whereas the transparent film still maintains a transmittance of 81%. The integrated efficient EMI SE and high transmittance are superior to those of most previously reported transparent EMI shielding materials. Moreover, our transparent films exhibit a highly reliable shielding ability in a complex service environment, with 98 and 96% EMI SE retentions even after 30 min of ultrasound treatment and 5000 bending cycles (1.5 mm radius), respectively. The comprehensive performance that is associated with the facile fabrication strategy imparts the CA/AgNW/PU film with great potential as an optimized EMI shielding material in emerging optoelectronic devices, such as flexible solar cells, displays, and touch panels.

Photo current generation in RGO - CdS nanorod thin film device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, Koushik; Chakrabarty, Sankalpita; Ibrahim, Sk.

2016-05-23

Herein, we report the synthesis and characterization of reduced graphene oxide (RGO) - cadmium sulfide (CdS) nanocomposite materials. The reduction of GO, formation of CdS and decoration of CdS onto RGO sheets were done in a one- pot solvothermal process. We have observed that the PL intensity for CdS nanorods remarkably quenched after the attachment of RGO, which established the photo induced charge transformation from the CdS nanorod to RGO sheets through the RGO-CdS interface. The optoelectronic transport properties of our fabricated large area thin film device exhibits excellent photo induced charge generation under simulated solar light illumination. The photomore » sensitivity of the device increases linearly with the increase of illuminated light intensity. The RGO-CdS composite exhibits enhance photocatalytic dye degradation efficiency in compare to control CdS under simulated solar light illumination.« less

Fabrication of efficient TiO2-RGO heterojunction composites for hydrogen generation via water-splitting: Comparison between RGO, Au and Pt reduction sites

NASA Astrophysics Data System (ADS)

El-Bery, Haitham M.; Matsushita, Yoshihisa; Abdel-moneim, Ahmed

2017-11-01

A facile one-step synthesis approach of M/TiO2/RGO (M = Au or Pt) ternary composite by hydrothermal treatment for hydrogen generation via water-splitting was investigated. Photocurrent response measurements revealed that TiO2 (P25) nanoparticles anchored on the reduced graphene oxide (RGO) surface exhibited a p-n heterojunction interface by changing the photocurrent direction with the applied bias from reverse to forward potential. H2 evolution rate of TiO2/RGO (5 wt.%) composite was substantially enhanced by 12-fold in comparison to bare TiO2 under simulated solar light irradiation. Cyclic volatmmetry measurements manifested, that the optimized 0.3 wt.% of platinum metal loaded on TiO2/RGO composite was the most active catalytic reduction sites for hydrogen generation reaction with an initial hydrogen rate of 670 μmol h-1. This study sheds the light on the tunable semiconductor type of TiO2/RGO composite fabricated by solution mixing pathway and its merits to improve the photocatalytic activity.

Synergetic Improvement in Thermal Conductivity and Flame Retardancy of Epoxy/Silver Nanowires Composites by Incorporating "Branch-Like" Flame-Retardant Functionalized Graphene.

PubMed

Feng, Yuezhan; Li, Xiongwei; Zhao, Xiaoyu; Ye, Yunsheng; Zhou, Xingping; Liu, Hu; Liu, Chuntai; Xie, Xiaolin

2018-06-27

The significant fire hazards on the polymer-based thermal interface materials (TIM) used in electronic devices are but often neglected. Also, high filler loading with the incident deterioration of mechanical, thermal, and processing properties limits the further application of the traditional polymer-based TIMs. In this work, a ternary TIMs with epoxy resin (EP) matrix, silver nanowires (AgNWs), and a small amount of flame-retardant functionalized graphene (GP-DOPO) were proposed to address the above questions. Briefly, a facile "branch-like" strategy with a polymer as the backbone and flame-retardant molecule as the branch was first used to functionalize reduced graphene oxide (RGO) toward increasing the flame-retardant grafting ratio and RGO's compatibility in matrix, and the resulted GP-DOPO was then in situ introduced into the EP/AgNW composites. As expected, the incorporation of GP-DOPO (2 wt %) can increase the thermal conductivity to 1.413 W/(m K) at a very low AgNW loading (4 vol %), which is 545 and 56% increments compared to pure EP and EP/AgNW, respectively. The prominent improvement in thermal conductivity was put down to the synergetic effect of AgNW and GP-DOPO, i.e., the improving dispersion and bridging effect for AgNWs by adding GP-DOPO. Moreover, the high flame-retardant grafting amount and the excellent compatibility of GP-DOPO resulted in a strong catalytic charring effect on EP matrix, which further formed a robust protective char layer by combining the AgNW and graphene network. Therefore, the flame retardancy of EP/AgNW was significantly improved by introducing GP-DOPO, i.e., the peak heat release rate, total heat release and total smoke production reduced by 27.0, 32.4, and 30.9% reduction compared to EP/AgNW, respectively.

Two-Dimensional Titanium Carbide/RGO Composite for High-Performance Supercapacitors.

PubMed

Zhao, Chongjun; Wang, Qian; Zhang, Huang; Passerini, Stefano; Qian, Xiuzhen

2016-06-22

Ti3C2Tx, a 2D titanium carbide in the MXenes family, is obtained from Ti3AlC2 through selective etching of the Al layer. Due to its good conductivity and high volumetric capacitance, Ti3C2Tx is regarded as a promising candidate for supercapacitors. In this paper, the fabrication of Ti3C2Tx/RGO composites with different proportions of Ti3C2Tx and RGO is reported, in which RGO acts as a conductive "bridge" to connect different Ti3C2Tx blocks and a matrix to alleviate the volume change during charge/discharge process. In addition, RGO nanosheets can serve as a second nanoscale current collector and support as well for the electrode. The electrochemical performance of the as-fabricated Ti3C2Tx/RGO electrodes, characterized by CV, GCD, and EIS, are also reported. A highest specific capacitance (Cs) of 154.3 F/g at 2 A/g is obtained at the Ti3C2Tx: RGO weight ratio of 7:1 combined with an outstanding capacity retention (124.7 F/g) after 6000 cycles at 4 A/g.

Superior Field Emission Properties of Layered WS2-RGO Nanocomposites

PubMed Central

Rout, Chandra Sekhar; Joshi, Padmashree D.; Kashid, Ranjit V.; Joag, Dilip S.; More, Mahendra A.; Simbeck, Adam J.; Washington, Morris; Nayak, Saroj K.; Late, Dattatray J.

2013-01-01

We report here the field emission studies of a layered WS2-RGO composite at the base pressure of ~1 × 10−8 mbar. The turn on field required to draw a field emission current density of 1 μA/cm2 is found to be 3.5, 2.3 and 2 V/μm for WS2, RGO and the WS2-RGO composite respectively. The enhanced field emission behavior observed for the WS2-RGO nanocomposite is attributed to a high field enhancement factor of 2978, which is associated with the surface protrusions of the single-to-few layer thick sheets of the nanocomposite. The highest current density of ~800 μA/cm2 is drawn at an applied field of 4.1 V/μm from a few layers of the WS2-RGO nanocomposite. Furthermore, first-principles density functional calculations suggest that the enhanced field emission may also be due to an overalp of the electronic structures of WS2 and RGO, where graphene-like states are dumped in the region of the WS2 fundamental gap. PMID:24257504

Dynamically tunable electromagnetically-induced-transparency-like resonances in graphene nanoring and nanodisk hybrid metamaterials

NASA Astrophysics Data System (ADS)

Chen, De-Chao; Li, Hong-Ju; Xia, Sheng-Xuan; Qin, Meng; Zhai, Xiang; Wang, Ling-Ling

2017-08-01

A tunable electromagnetically-induced-transparency-like (EIT-like) device is proposed numerically and theoretically in the mid-infrared region, which is composed of periodically patterned ring and disk graphene. Distinguished from the commonly used three-level system, the hybridization of the plasmon mode is applied to describing and explaining the EIT-like phenomenon in the proposed systems. What is more, further researches have revealed that the spectral position of the transparency window can be tuned not only by geometrically changing the couple distance in graphene nanostructures, but also by dynamically altering the radius of the graphene nanodisk and the chemical potential of the graphene. At the transparency window, there exist large optical delays, which can slow down the speed of light in vacuum. This work may pave the way to the development of applications including tunable sensors, slow-light devices, and optical switches.

Polyaniline/Fe3O4-RGO Nanocomposites for Microwave Absorption

NASA Astrophysics Data System (ADS)

Mathew, Jithin; Sathishkumar, M.; Kothurkar, Nikhil K.; Senthilkumar, R.; Sabarish Narayanan, B.

2018-02-01

Fe3O4 nanoparticles were synthesized by co-precipitation of ferric chloride (FeCl3) and ferrous chloride (FeCl2). Reduced graphene oxide (RGO) was prepared by reducing the graphene oxide, which was synthesized by Hummer’s method, using hydrazine hydrate. Three nanocomposites based on sodium dodecyl benzene sulphonate (SDBS)-doped polyaniline were synthesized through in situ polymerization in the presence of the fillers (i) Fe3O4, (ii) reduced graphene oxide (RGO) and (iii) Fe3O4-decorated RGO respectively. The synthesized PANI and the composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. Their microstructures, electrical conductivities, and EMI shielding effectiveness were studied. The nanocomposite containing 10 % RGO showed the maximum electrical conductivity and the one with 10 % RGO and 10 % Fe3O4 showed the maximum EMI shielding effectiveness of 7.5 dB for a 1 mm thick sample.

Sonochemical assisted synthesis MnO2/RGO nanohybrid as effective electrode material for supercapacitor.

PubMed

Ghasemi, Shahram; Hosseini, Sayed Reza; Boore-Talari, Omid

2018-01-01

Manganese dioxide (MnO 2 ) needle-like nanostructures are successfully synthesized by a sonochemical method from an aqueous solution of potassium bromate and manganese sulfate. Also, hybride of MnO 2 nanoparticles wrapped with graphene oxide (GO) nanosheets are fabricated through an electrostatic coprecipitation procedure. With adjusting pH at 3.5, positive and negative charges are created on MnO 2 and on GO, respectively which can electrostatically attract to each other and coprecipitate. Then, MnO 2 /GO pasted on stainless steel mesh is electrochemically reduced by applying -1.1V to obtain MnO 2 /RGO nanohybrid. The structure and morphology of the MnO 2 and MnO 2 /RGO nanohybrid are examined by Raman spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), field emission-scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDX), and thermal gravimetric analysis (TGA). The capacitive behaviors of MnO 2 and MnO 2 /RGO active materials on stainless steel meshes are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge test and electrochemical impedance spectroscopy (EIS) by a three-electrode experimental setup in an aqueous solution of 0.5M sodium sulfate in the potential window of 0.0-1.0V. The electrochemical investigations reveal that MnO 2 /RGO exhibits high specific capacitance (C s ) of 375Fg -1 at current density of 1Ag -1 and good cycle stability (93% capacitance retention after 500 cycles at a scan rate of 200mVs -1 ). The obtained results give good prospect about the application of electrostatic coprecipitation method to prepare graphene/metal oxides nanohybrids as effective electrode materials for supercapacitors. Copyright © 2017 Elsevier B.V. All rights reserved.

Vacuum-Assisted Low-Temperature Synthesis of Reduced Graphene Oxide Thin-Film Electrodes for High-Performance Transparent and Flexible All-Solid-State Supercapacitors.

PubMed

Aytug, Tolga; Rager, Matthew S; Higgins, Wesley; Brown, Forrest G; Veith, Gabriel M; Rouleau, Christopher M; Wang, Hui; Hood, Zachary D; Mahurin, Shannon M; Mayes, Richard T; Joshi, Pooran C; Kuruganti, Teja

2018-04-04

Simple and easily integrated design of flexible and transparent electrode materials affixed to polymer-based substrates hold great promise to have a revolutionary impact on the functionality and performance of energy storage devices for many future consumer electronics. Among these applications are touch sensors, roll-up displays, photovoltaic cells, health monitors, wireless sensors, and wearable communication devices. Here, we report an environmentally friendly, simple, and versatile approach to produce optically transparent and mechanically flexible all-solid-state supercapacitor devices. These supercapacitors were constructed on tin-doped indium oxide coated polyethylene terephthalate substrates by intercalation of a polymer-based gel electrolyte between two reduced graphene oxide (rGO) thin-film electrodes. The rGO electrodes were fabricated simply by drop-casting of graphene oxide (GO) films, followed by a novel low-temperature (≤250 °C) vacuum-assisted annealing approach for the in situ reduction of GO to rGO. A trade-off between the optical transparency and electrochemical performance is determined by the concentration of the GO in the initial dispersion, whereby the highest capacitance (∼650 μF cm -2 ) occurs at a relatively lower optical transmittance (24%). Notably, the all-solid-state supercapacitors demonstrated excellent mechanical flexibility with a capacity retention rate above 90% under various bending angles and cycles. These attributes underscore the potential of the present approach to provide a path toward the realization of thin-film-based supercapacitors as flexible and transparent energy storage devices for a variety of practical applications.

Large bandgap reduced graphene oxide (rGO) based n-p + heterojunction photodetector with improved NIR performance

NASA Astrophysics Data System (ADS)

Singh, Manjri; Kumar, Gaurav; Prakash, Nisha; Khanna, Suraj P.; Pal, Prabir; Singh, Surinder P.

2018-04-01

Integration of two-dimensional reduced graphene oxide (rGO) with conventional Si semiconductor offers novel strategies for realizing broadband photodiode with enhanced device performance. In this quest, we have synthesized large bandgap rGO and fabricated metal-free broadband (300–1100 nm) back-to-back connected np-pn hybrid photodetector utilizing drop casted n-rGO/p +-Si heterojunctions with high performance in NIR region (830 nm). With controlled illumination, the device exhibited a peak responsivity of 16.7 A W‑1 and peak detectivity of 2.56 × 1012 Jones under 830 nm illumination (11 μW cm‑2) at 1 V applied bias with fast response (∼460 μs) and recovery time (∼446 μs). The fabricated device demonstrated excellent repeatability, durability and photoswitching behavior with high external quantum efficiency (∼2.5 × 103%), along with ultrasensitive behavior at low light conditions.

Effect of supersonic spraying impact velocity on opto-electric properties of transparent conducting flexible films consisting of silver nanowire, ITO, and polyimide multilayers

DOE PAGES

Kim, Tae-Gun; Lee, Jong-Gun; Park, Chan-Woo; ...

2017-12-26

We demonstrate the use of supersonic spraying for the deposition of silver nanowires (AgNWs) on a flexible polyimide (PI) substrate for the formation of transparent and conducting films (TCF) as an alternative to nonflexible ITO (indium tin oxide). The self-fused intersections of the NWs resulted in films with a low sheet resistance (Rs = 31 ..omega../sq) and fairly high transmittance (Tr = 92%) on a glass substrate. The effect of the impact speed of the supersonically sprayed AgNWs on the opto-electric properties of the flexible TCF was evaluated by varying the spray coating conditions. The fabricated films were characterized bymore » X-ray diffraction analysis, atomic force microscopy, ultraviolet-visible spectroscopy, and scanning electron microscopy. Finally, cyclic bending tests were performed on the PI/AgNW films as well as PI/ZnO/indium tin oxide/AgNW films, and the changes in their electrical properties with bending were compared.« less

Effect of supersonic spraying impact velocity on opto-electric properties of transparent conducting flexible films consisting of silver nanowire, ITO, and polyimide multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Tae-Gun; Lee, Jong-Gun; Park, Chan-Woo

We demonstrate the use of supersonic spraying for the deposition of silver nanowires (AgNWs) on a flexible polyimide (PI) substrate for the formation of transparent and conducting films (TCF) as an alternative to nonflexible ITO (indium tin oxide). The self-fused intersections of the NWs resulted in films with a low sheet resistance (Rs = 31 ..omega../sq) and fairly high transmittance (Tr = 92%) on a glass substrate. The effect of the impact speed of the supersonically sprayed AgNWs on the opto-electric properties of the flexible TCF was evaluated by varying the spray coating conditions. The fabricated films were characterized bymore » X-ray diffraction analysis, atomic force microscopy, ultraviolet-visible spectroscopy, and scanning electron microscopy. Finally, cyclic bending tests were performed on the PI/AgNW films as well as PI/ZnO/indium tin oxide/AgNW films, and the changes in their electrical properties with bending were compared.« less

Fabrication of graphene-fullerene hybrid by self-assembly and its application as support material for methanol electrocatalytic oxidation reaction

NASA Astrophysics Data System (ADS)

Zhang, Xuan; Zhang, Jia-Wei; Xiang, Ping-Hua; Qiao, Jinli

2018-05-01

Graphene-fullerene hybrids were facilely fabricated by self-assembly of graphene oxide (GO) and multi-substituted fulleropyrrolidines (PyrC60). The hybrids (GO-PyrC60) were applied as support materials to deposit Pd nanoparticle catalyst by a simple hydrothermal co-reduction approach. The as-prepared electrocatalysts (Pd/RGO-PyrC60) were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. The RGO-PyrC60 hybrid supported Pd catalyst with the optimal ratio of RGO to PyrC60, exhibited much enhanced electrocatalytic activity and stability toward methanol oxidation reaction (MOR) compared to the RGO alone supported Pd as well as commercial Pd/C. The introduction of fulleropyrrolidine as spacer between graphene layers could increase the electrocatalytic activity and improve the long-term stability. This strategy may contribute to developing graphene-fullerene hydrids as effective support materials for advanced electrocatalysts.

Successful entrapment of carbon dots within flexible free-standing transparent mesoporous organic-inorganic silica hybrid films for photonic applications

NASA Astrophysics Data System (ADS)

Vassilakopoulou, Anastasia; Georgakilas, Vasilios; Vainos, Nikolaos; Koutselas, Ioannis

2017-04-01

The effective entrapment of Carbon dots (CDs) into a polymer-silica hybrid matrix, formed as free standing transparent flexible films, is presented. The composite's synthesis, characterization, device application and properties -mechanical, thermal and optical- are being provided and discussed. CDs of 3 nm mean size with strong photoluminescence are embedded into a silica matrix during the sol-gel procedure, using tetraethyl orthosilicate as the precursor and F127 triblock copolymer as the structure directing agent under acidic conditions. The final hybrid nanostructure forms free standing transparent films that show high flexibility and long term stable CDs luminescence indicating the protective character of the hybrid matrix. It is crucial that the photoluminescence of the hybrid's CDs is not seriously affected after thermal treatment at 550 °C for 30 min. Moreover, the herein reported hybrid is demonstrated to be suitable for the fabrication of advanced photonic structures using soft lithography processes due to its low shrinkage and distortion upon drying, both attributable to its porosity. Finally, it is reported that addition of F127 ethanolic solution in aqueous solution of CDs induces a blue-shift of their photoluminescence.

Transparent organic/inorganic hybrid sol-gel materials based on perfluorinated polymers and silica

NASA Astrophysics Data System (ADS)

Wojcik, Anna B.; Klein, Lisa C.

1996-01-01

Two types of hybrid gels based on silica and perfluorinated polymers have been prepared. The first type involves a perfluorinated polymer containing acrylate groups. Perfluoropolyether diol diacrylate (PFDA) was functionalized by reacting it with (3-mercapto-propyl) trimethoxysilane by a Michael addition. The resulting silyl derivative (PFDAS) was able to copolymerize with a silica precursor, tetraethylorthosilicate (TEOS), resulting in perfluorinated polymer/silica hybrid gels. For the second type, perfluoroalkylsilane (FAS), vinyltriethoxysilane (VTES), and TEOS were polymerized in one step. In both cases, the gels were transparent, crack-free and water repellent. Since the inorganic and organic components are covalently bonded to each other, these materials can be classified as organic/inorganic copolymers.

Enhanced performances of dye-sensitized solar cells based on Au-TiO2 and Ag-TiO2 plasmonic hybrid nanocomposites

NASA Astrophysics Data System (ADS)

Ran, Huili; Fan, Jiajie; Zhang, Xiaoli; Mao, Jing; Shao, Guosheng

2018-02-01

Novel double-layer films were prepared and applied to dye-sensitized solar cells (DSSCs) using commercial TiO2 nanoparticles as a bonding underlayer and noble metal (Au and Ag) nanoparticles (NP) and nanowires (NW) incorporated to hybrid TiO2 composites, consisting of 3 dimensional (3D) hierarchical microspheres, 3D hollow spheres, 2 dimensional (2D) nanosheets and commercial P25 nanoparticles, as multifunctional light scattering overlayer. The influence of Au NP, Ag NP, Au NW, and Ag NW on of microstructures of the film electrodes and the photovoltaic (PV) performances of DSSCs was investigated. The result revealed that the ranges and intensity of sunlight absorption, the photo capture ability for dye molecules of the hybrid nanocomposite film electrodes, and the photoelectric conversion efficiency (PCE) of the cells were all significantly enhanced due to the plasmonic effect of the noble metal nanostructures. All composite DSSCs with noble metal nanostructures have higher PCE than the pure TiO2 solar cell. This is attributed the improved electron transport of the noble metal nanostructures, and the improvement of light absorption because of their local surface plasmon resonance (LSPR) effect. Under optical conditions, a PCE of 5.74% was obtained in the TiO2-AgNW DSSC, representing a 25.3% enhancement compared to a reference solar cell based on pure TiO2 film (4.58%). The main reason of the advancement is the improved electron transport of AgNW, the light absorption enhancement on account of the LSPR effect of AgNW, and increased light scattering due to the incorporation of the large one dimensional AgNWs within the photo-anode.

Photoactive films of photosystem I on transparent reduced graphene oxide electrodes.

PubMed

Darby, Emily; LeBlanc, Gabriel; Gizzie, Evan A; Winter, Kevin M; Jennings, G Kane; Cliffel, David E

2014-07-29

Photosystem I (PSI) is a photoactive electron-transport protein found in plants that participates in the process of photosynthesis. Because of PSI's abundance in nature and its efficiency with charge transfer and separation, there is a great interest in applying the protein in photoactive electrodes. Here, we developed a completely organic, transparent, conductive electrode using reduced graphene oxide (RGO) on which a multilayer of PSI could be deposited. The resulting photoactive electrode demonstrated current densities comparable to that of a gold electrode modified with a multilayer film of PSI and significantly higher than that of a graphene electrode modified with a monolayer film of PSI. The relatively large photocurrents produced by integrating PSI with RGO and using an opaque, organic mediator can be applied to the facile production of more economic solar energy conversion devices.

Hydrothermal preparation of ZnO-reduced graphene oxide hybrid with high performance in photocatalytic degradation

NASA Astrophysics Data System (ADS)

Zhou, Xun; Shi, Tiejun; Zhou, Haiou

2012-06-01

Hydrothermal method was utilized to prepare reduced graphene oxide (RGO) and fabricate ZnO-RGO hybrid (ZnO-RGO) with zinc nitrate hexahydrate and graphene oxide (GO) as raw materials under pH value of 11 adjusted by ammonia water. During the process of reduction of GO, hydrothermal condition with ammonia provided thermal and chemical factors to synthesize RGO. The retained functional groups on RGO planes played an important role in anchoring ZnO to RGO, which was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy and photoluminescence spectra. The various mass ratios of zinc nitrate hexahydrate to GO used to prepare ZnO-RGO impacted significantly on the morphology of ZnO nanostructures such as nanoparticles and nanorods. And, the RGO sheets wrapped ZnO nanoparticles and nanorods very tightly. After the emission of photo electrons from ZnO, RGO in ZnO-RGO can effectively transfer the photo electrons to exhibit a high performance and reproducibility in photocatalytic degradation toward methylene blue (MB) absorbed on the surface of RGO through π-π conjugation.

Waste to wealth concept: Disposable RGO filter paper for flexible temperature sensor applications

NASA Astrophysics Data System (ADS)

Neella, Nagarjuna; Kedambaimoole, Vaishakh; Gaddam, Venkateswarlu; Nayak, M. M.; Rajanna, K.

2018-04-01

We have developed a flexible reduced graphene oxide (RGO) temperature sensor on filter paper based cellulose substrate using vacuum filtration method. One of the most commonly used synthesized methods for RGO thin films is vacuum filtration process. It has several advantages such as simple operation and good controllability. The structural analysis was carried out by FE-SEM, in which the surface morphology images confirm the formation of RGO nanostructures on the filter paper substrate. It was observed that the pores of the filter paper were completely filled with the RGO material during the filtration process, subsequently the formation of continuous RGO thin films. As a results, the RGO films exhibits a piezoresistive property. The resulted RGO based films on the filter paper reveals the semiconducting behavior having sensitivity of 0.278 Ω /°C and negative temperature coefficient (NTC) about -0.00254 Ω/ Ω / °C. Thus, we demonstrate a simplified way for the fabrication of RGO films on filter paper that possesses better and easier measurable macroscopic electrical properties. Our approach is for easy way of electronics, cost-effective and environment friendly fabrication route for flexible conducting graphene films on filter paper. This will enable for the potential applications in flexible electronics in various fields including biomedical, automobile and aerospace engineering.

Planar silver nanowire, carbon nanotube and PEDOT:PSS nanocomposite transparent electrodes

NASA Astrophysics Data System (ADS)

Stapleton, Andrew J.; Yambem, Soniya D.; Johns, Ashley H.; Afre, Rakesh A.; Ellis, Amanda V.; Shapter, Joe G.; Andersson, Gunther G.; Quinton, Jamie S.; Burn, Paul L.; Meredith, Paul; Lewis, David A.

2015-04-01

Highly conductive, transparent and flexible planar electrodes were fabricated using interwoven silver nanowires and single-walled carbon nanotubes (AgNW:SWCNT) in a PEDOT:PSS matrix via an epoxy transfer method from a silicon template. The planar electrodes achieved a sheet resistance of 6.6 ± 0.0 Ω/□ and an average transmission of 86% between 400 and 800 nm. A high figure of merit of 367 Ω-1 is reported for the electrodes, which is much higher than that measured for indium tin oxide and reported for other AgNW composites. The AgNW:SWCNT:PEDOT:PSS electrode was used to fabricate low temperature (annealing free) devices demonstrating their potential to function with a range of organic semiconducting polymer:fullerene bulk heterojunction blend systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Dustin; Zhao, Fangchao; Tong, Kwing

Here, the extended lifetime of organic light-emitting diodes (OLEDs) based on enhanced electrical stability of a silver nanowire (AgNW) transparent conductive electrode is reported. Specifically, in depth investigation is performed on the ability of atomic layer deposition deposited zinc oxide (ZnO) on AgNWs to render the nanowires electrically stable during electrical stressing at the range of operational current density used for OLED lighting. ZnO-coated AgNWs have been observed to show no electrical, optical, or morphological degradation, while pristine AgNW electrodes have become unusable for optoelectronic devices due to dramatic decreases in conductivity, transparency, and fragmentation of the nanowire network atmore » ≈150 mA cm -2. When fabricated into OLED substrates, resulting OLEDs fabricated on the ZnO-AgNW platform exhibit a 140% increase in lifetime when compared to OLEDs fabricated on indium tin oxide (ITO)/glass, and ≈20% when compared to OLEDs fabricated on AgNW based substrates. While both ZnO-coated and pristine AgNW substrates outperform ITO/glass due to the lower current densities required to drive the device, morphological stability in response to current stressing is responsible for the enhancement of lifetime of ZnO-AgNW based OLEDs compared to pristine AgNW based OLEDs.« less

Mitigation of Electrical Failure of Silver Nanowires under Current Flow and the Application for Long Lifetime Organic Light-Emitting Diodes

DOE PAGES

Chen, Dustin; Zhao, Fangchao; Tong, Kwing; ...

2016-07-08

Here, the extended lifetime of organic light-emitting diodes (OLEDs) based on enhanced electrical stability of a silver nanowire (AgNW) transparent conductive electrode is reported. Specifically, in depth investigation is performed on the ability of atomic layer deposition deposited zinc oxide (ZnO) on AgNWs to render the nanowires electrically stable during electrical stressing at the range of operational current density used for OLED lighting. ZnO-coated AgNWs have been observed to show no electrical, optical, or morphological degradation, while pristine AgNW electrodes have become unusable for optoelectronic devices due to dramatic decreases in conductivity, transparency, and fragmentation of the nanowire network atmore » ≈150 mA cm -2. When fabricated into OLED substrates, resulting OLEDs fabricated on the ZnO-AgNW platform exhibit a 140% increase in lifetime when compared to OLEDs fabricated on indium tin oxide (ITO)/glass, and ≈20% when compared to OLEDs fabricated on AgNW based substrates. While both ZnO-coated and pristine AgNW substrates outperform ITO/glass due to the lower current densities required to drive the device, morphological stability in response to current stressing is responsible for the enhancement of lifetime of ZnO-AgNW based OLEDs compared to pristine AgNW based OLEDs.« less

Pressure-sensitive strain sensor based on a single percolated Ag nanowire layer embedded in colorless polyimide

NASA Astrophysics Data System (ADS)

Lee, Chan-Jae; Jun, Sungwoo; Ju, Byeong-Kwon; Kim, Jong-Woong

2017-06-01

This paper presents the fabrication of an elastomer-free, transparent, pressure-sensitive strain sensor consisting of a specially designed silver nanowire (AgNW) pattern and colorless polyimide (cPI). A percolated AgNW network was patterned with a simple tandem compound circuit, which was then embedded in the surface of the cPI via inverted layer processing. The resulting film-type sensor was highly transparent ( 93.5% transmittance at 550 nm) and mechanically stable (capable of resisting 10000 cycles of bending to a 500 μm radius of curvature). We demonstrated that a thin, transparent, and mechanically stable electrode can be produced using a combination of AgNWs and cPI, and used to produce a system sensitive to pressure-induced bending. The capacitance of the AgNW tandem compound electrode pattern grew via fringing, which increased with the pressure-induced bending applied to the surface of the sensor. The sensitivity was four times higher than that of an elastomeric pressure sensor made with the same design. Finally, we demonstrated a skin-like pressure sensor attached to the inside wrist of a human arm.

Large scale silver nanowires network fabricated by MeV hydrogen (H+) ion beam irradiation

NASA Astrophysics Data System (ADS)

Honey, S.; Naseem, S.; Ishaq, A.; Maaza, M.; Bhatti, M. T.; Wan, D.

2016-04-01

A random two-dimensional large scale nano-network of silver nanowires (Ag-NWs) is fabricated by MeV hydrogen (H+) ion beam irradiation. Ag-NWs are irradiated under H+ ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H+ ion beam-induced welding of Ag-NWs at intersecting positions. H+ ion beam induced welding is confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, the structure of Ag NWs remains stable under H+ ion beam, and networks are optically transparent. Morphology also remains stable under H+ ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under MeV H+ ion beam irradiation. The results exhibit that the formation of Ag-NW network proceeds through three steps: ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from MeV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices. Project supported by the National Research Foundation of South Africa (NRF), the French Centre National pour la Recherche Scientifique, iThemba-LABS, the UNESCO-UNISA Africa Chair in Nanosciences & Nanotechnology, the Third World Academy of Science (TWAS), Organization of Women in Science for the Developing World (OWSDW), the Abdus Salam ICTP via the Nanosciences African Network (NANOAFNET), and the Higher Education Commission (HEC) of Pakistan.

Pd/RGO modified carbon felt cathode for electro-Fenton removing of EDTA-Ni.

PubMed

Zhang, Zhen; Zhang, Junya; Ye, Xiaokun; Hu, Yongyou; Chen, Yuancai

Ethylenediaminetetraacetic acid (EDTA) forms stable complexes with toxic metals such as nickel due to its strong chelation. The electro-Fenton (EF) process using a cathode made from palladium (Pd), reduced graphene oxide (RGO) and carbon felt, fed with air, exhibited high activities and stability for the removal of 10 mg L(-1) EDTA-Ni solution. Pd/RGO catalyst was prepared by one-pot synthesis; the scanning electron microscopy and X-ray diffraction analysis indicated nanoparticles and RGO were well distributed on carbon felt, forming three dimensional architecture with both large macropores and a mesoporous structure. The cyclic voltammetric results showed that the presence of RGO in Pd/RGO/carbon felt significantly increased the current response of two-electron reduction of O2 (0.45 V). The key factors influencing the removal efficiency of EDTA-Ni, such as pH, current and Fe(2+) concentration, were investigated. Under the optimum conditions, the removal efficiency of EDTA-Ni reached 83.8% after 100 min EF treatment. Mechanism analysis indicated that the introduction of RGO in Pd/RGO/carbon felt significantly enhanced the electrocatalytic activities by inducing •OH in the EF process; direct H2O2 oxidation still accounted for a large amount of EDTA-Ni removal efficiency.

RGO modified Ni doped FeOOH for enhanced electrochemical and photoelectrochemical water oxidation

NASA Astrophysics Data System (ADS)

Zhang, Xiaofan; Zhang, Bingyan; Liu, Shuangshuang; Kang, Hongwei; Kong, Weiqian; Zhang, Shouren; Shen, Yan; Yang, Baocheng

2018-04-01

Ni,Fe-based (oxy)hydroxides have been one of the most active catalysts for the oxygen evolution reaction. In this article, reduced graphene oxide supported Ni doped FeOOH (RGO/Ni:FeOOH) was prepared for electrochemical and photoelectrochemical (PEC) water oxidation. The RGO/Ni:FeOOH exhibited a lower over-potential (260 mV at 10 mA cm-2) and smaller Tafel slope (32.3 mV dec-1) than that of the FeOOH and Ni:FeOOH. Such significant enhancement is attributed to Ni doping and RGO, which reduce the over-potential, improve the conductivity and enlarge surface areas. Besides, RGO/Ni:FeOOH decorated the TiO2 nanorods (NRs) was also fabricated for photoelectrochemical (PEC) water oxidation, which exhibited a higher photocurrent density and lower onset potential than that of TiO2 NRs the bare under illumination due to the synergistic effect of RGO and Ni:FeOOH. These results demonstrate the RGO/Ni:FeOOH has great promising as a co-catalyst to improve the PEC performance.

Planar silver nanowire, carbon nanotube and PEDOT:PSS nanocomposite transparent electrodes

PubMed Central

Stapleton, Andrew J; Yambem, Soniya D; Johns, Ashley H; Afre, Rakesh A; Ellis, Amanda V; Shapter, Joe G; Andersson, Gunther G; Quinton, Jamie S; Burn, Paul L; Meredith, Paul

2015-01-01

Highly conductive, transparent and flexible planar electrodes were fabricated using interwoven silver nanowires and single-walled carbon nanotubes (AgNW:SWCNT) in a PEDOT:PSS matrix via an epoxy transfer method from a silicon template. The planar electrodes achieved a sheet resistance of 6.6 ± 0.0 Ω/□ and an average transmission of 86% between 400 and 800 nm. A high figure of merit of 367 Ω−1 is reported for the electrodes, which is much higher than that measured for indium tin oxide and reported for other AgNW composites. The AgNW:SWCNT:PEDOT:PSS electrode was used to fabricate low temperature (annealing free) devices demonstrating their potential to function with a range of organic semiconducting polymer:fullerene bulk heterojunction blend systems. PMID:27877771

Enhanced thermal diffusivity of copperbased composites using copper-RGO sheets

NASA Astrophysics Data System (ADS)

Kim, Sangwoo; Kwon, Hyouk-Chon; Lee, Dohyung; Lee, Hyo-Soo

2017-11-01

The synthesis of copper-reduced graphene oxide (RGO) sheets was investigated in order to control the agglutination of interfaces and develop a manufacturing process for copper-based composite materials based on spark plasma sintering. To this end, copper-GO (graphene oxide) composites were synthesized using a hydrothermal method, while the copper-reduced graphene oxide composites were made by hydrogen reduction. Graphene oxide-copper oxide was hydrothermally synthesized at 80 °C for 5 h, and then annealed at 800 °C for 5 h in argon and hydrazine rate 9:1 to obtain copper-RGO flakes. The morphology and structure of these copper-RGO sheets were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. After vibratory mixing of the synthesized copper-RGO composites (0-2 wt%) with copper powder, they were sintered at 600 °C for 5 min under100 MPa of pressure by spark plasma sintering process. The thermal diffusivity of the resulting sintered composite was characterized by the laser flash method at 150 °C.

Core-shell LiFePO4 /carbon-coated reduced graphene oxide hybrids for high-power lithium-ion battery cathodes.

PubMed

Ha, Sung Hoon; Lee, Yun Jung

2015-01-26

Core-shell carbon-coated LiFePO4 nanoparticles were hybridized with reduced graphene (rGO) for high-power lithium-ion battery cathodes. Spontaneous aggregation of hydrophobic graphene in aqueous solutions during the formation of composite materials was precluded by employing hydrophilic graphene oxide (GO) as starting templates. The fabrication of true nanoscale carbon-coated LiFePO4 -rGO (LFP/C-rGO) hybrids were ascribed to three factors: 1) In-situ polymerization of polypyrrole for constrained nanoparticle synthesis of LiFePO4 , 2) enhanced dispersion of conducting 2D networks endowed by colloidal stability of GO, and 3) intimate contact between active materials and rGO. The importance of conducting template dispersion was demonstrated by contrasting LFP/C-rGO hybrids with LFP/C-rGO composites in which agglomerated rGO solution was used as the starting templates. The fabricated hybrid cathodes showed superior rate capability and cyclability with rates from 0.1 to 60 C. This study demonstrated the synergistic combination of nanosizing with efficient conducting templates to afford facile Li(+) ion and electron transport for high power applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Efficient low-temperature transparent electrocatalytic layers based on graphene oxide nanosheets for dye-sensitized solar cells.

PubMed

Seo, Seon Hee; Jeong, Eun Ji; Han, Joong Tark; Kang, Hyon Chol; Cha, Seung I; Lee, Dong Yoon; Lee, Geon-Woong

2015-05-27

Electrocatalytic materials with a porous structure have been fabricated on glass substrates, via high-temperature fabrication, for application as alternatives to platinum in dye-sensitized solar cells (DSCs). Efficient, nonporous, nanometer-thick electrocatalytic layers based on graphene oxide (GO) nanosheets were prepared on plastic substrates using electrochemical control at low temperatures of ≤100 °C. Single-layer, oxygen-rich GO nanosheets prepared on indium tin oxide (ITO) substrates were electrochemically deoxygenated in acidic medium within a narrow scan range in order to obtain marginally reduced GO at minimum expense of the oxygen groups. The resulting electrochemically reduced GO (E-RGO) had a high density of residual alcohol groups with high electrocatalytic activity toward the positively charged cobalt-complex redox mediators used in DSCs. The ultrathin, alcohol-rich E-RGO layer on ITO-coated poly(ethylene terephthalate) was successfully applied as a lightweight, low-temperature counter electrode with an extremely high optical transmittance of ∼97.7% at 550 nm. A cobalt(II/III)-mediated DSC employing the highly transparent, alcohol-rich E-RGO electrode exhibited a photovoltaic power conversion efficiency of 5.07%. This is superior to that obtained with conventionally reduced GO using hydrazine (3.94%) and even similar to that obtained with platinum (5.10%). This is the first report of a highly transparent planar electrocatalytic layer based on carbonaceous materials fabricated on ITO plastics for application in DSCs.

Study of Ag/RGO/ITO sandwich structure for resistive switching behavior deposited on plastic substrate

NASA Astrophysics Data System (ADS)

Vartak, Rajdeep; Rag, Adarsh; De, Shounak; Bhat, Somashekhara

2018-05-01

We report here the use of facile and environmentally benign way synthesized reduced graphene oxide (RGO) for low-voltage non-volatile memory device as charge storing element. The RGO solutions have been synthesized using electrochemical exfoliation of battery electrode. The solution processed based RGO solution is suitable for large area and low-cost processing on plastic substrate. Room-temperature current-voltage characterisation has been carried out in Ag/RGO/ITO PET sandwich configuration to study the type of trap distribution. It is observed that in the low-voltage sweep, ohmic current is the main mechanism of current flow and trap filled/assisted conduction is observed at high-sweep voltage region. The Ag/RGO/ITO PET sandwich structure showed bipolar resistive switching behavior. These mechanisms can be analyzed based on oxygen availability and vacancies in the RGO giving rise to continuous least resistive path (conductive) and high resistance path along the structure. An Ag/RGO/ITO arrangement demonstrates long retention time with low operating voltage, low set/reset voltage, good ON/OFF ratio of 103 (switching transition between lower resistance state and higher resistance state and decent switching performance. The RGO memory showed decent results with an almost negligible degradation in switching properties which can be used for low-voltage and low-cost advanced flexible electronics.

Conductivity enhancement of silver nanowire networks via simple electrolyte solution treatment and solvent washing.

PubMed

Gu, Jiahui; Wang, Xuelin; Chen, Hongtao; Yang, Shihua; Feng, Huanhuan; Ma, Xing; Ji, Hongjun; Wei, Jun; Li, Mingyu

2018-06-29

As a promising replacement material for indium tin oxide in flexible electronics, silver nanowires (AgNWs) usually need complicated post-treatment to reduce the high contact resistance across the intersections when used as transparent conductive films. In this work, a widely applicable nano-joining method for improving the overall conductivity of AgNW networks with different kinds of electrolyte solutions is presented. By treatment with an electrolyte solution with appropriate ionic strengths, the insulating surfactant layer (polyvinylpyrrolidone, PVP) on the AgNWs could be desorbed, and the AgNW network could be densified. The sheet resistance of the AgNW film on a glass slide is reduced by 60.9% (from 67.5 to 26.4 Ohm sq -1 ) with a transmittance of 92.5%. High-resolution transmission electron microscopy analysis indicates that atomic diffusion occurs at the intersection of two AgNWs. Thus, metallurgical bonding on the nanometer scale is achieved across the junctions of the AgNWs, leading to a significant enhancement in the conductivity of the AgNW network.

Conductivity enhancement of silver nanowire networks via simple electrolyte solution treatment and solvent washing

NASA Astrophysics Data System (ADS)

Gu, Jiahui; Wang, Xuelin; Chen, Hongtao; Yang, Shihua; Feng, Huanhuan; Ma, Xing; Ji, Hongjun; Wei, Jun; Li, Mingyu

2018-06-01

As a promising replacement material for indium tin oxide in flexible electronics, silver nanowires (AgNWs) usually need complicated post-treatment to reduce the high contact resistance across the intersections when used as transparent conductive films. In this work, a widely applicable nano-joining method for improving the overall conductivity of AgNW networks with different kinds of electrolyte solutions is presented. By treatment with an electrolyte solution with appropriate ionic strengths, the insulating surfactant layer (polyvinylpyrrolidone, PVP) on the AgNWs could be desorbed, and the AgNW network could be densified. The sheet resistance of the AgNW film on a glass slide is reduced by 60.9% (from 67.5 to 26.4 Ohm sq‑1) with a transmittance of 92.5%. High-resolution transmission electron microscopy analysis indicates that atomic diffusion occurs at the intersection of two AgNWs. Thus, metallurgical bonding on the nanometer scale is achieved across the junctions of the AgNWs, leading to a significant enhancement in the conductivity of the AgNW network.

Acetylcholinesterase-reduced graphene oxide hybrid films for organophosphorus neurotoxin sensing via quartz crystal microbalance

NASA Astrophysics Data System (ADS)

Tang, Shi; Ma, Wenying; Xie, Guangzhong; Su, Yuanjie; Jiang, Yadong

2016-09-01

An acetylcholinesterase (AChE)-reduced graphene oxide (RGO) hybrid films based biosensor enabled by quartz crystal microbalance (QCM) has been developed for the detection of organophosphorus neurotoxin in gas phase at room temperature. To improve the sensing performance, RGO was used to immobilize large quantities of enzyme and provide a favorable microenvironment to maintain the enzyme activity. The experimental results reveal that the response of AChE-RGO/glutaraldehyde based sensors is about 8 times larger than that of the AChE with the sensitivity of 1.583 Hz/mg/m3. 1.0 mg amount of RGO, 5% concentration of glutaraldehyde and pH 6.8 is the optimal condition of this biosensor.

An 8.68% efficiency chemically-doped-free graphene-silicon solar cell using silver nanowires network buried contacts.

PubMed

Yang, Lifei; Yu, Xuegong; Hu, Weidan; Wu, Xiaolei; Zhao, Yan; Yang, Deren

2015-02-25

Graphene-silicon (Gr-Si) heterojunction solar cells have been recognized as one of the most low-cost candidates in photovoltaics due to its simple fabrication process. However, the high sheet resistance of chemical vapor deposited (CVD) Gr films is still the most important limiting factor for the improvement of the power conversion efficiency of Gr-Si solar cells, especially in the case of large device-active area. In this work, we have fabricated a novel transparent conductive film by hybriding a monolayer Gr film with silver nanowires (AgNWs) network soldered by the graphene oxide (GO) flakes. This Gr-AgNWs hybrid film exhibits low sheet resistance and larger direct-current to optical conductivity ratio, quite suitable for solar cell fabrication. An efficiency of 8.68% has been achieved for the Gr-AgNWs-Si solar cell, in which the AgNWs network acts as buried contacts. Meanwhile, the Gr-AgNWs-Si solar cells have much better stability than the chemically doped Gr-Si solar cells. These results show a new route for the fabrication of high efficient and stable Gr-Si solar cells.

Dual-functional Pt-on-Pd supported on reduced graphene oxide hybrids: peroxidase-mimic activity and an enhanced electrocatalytic oxidation characteristic.

PubMed

Zhang, Xiahong; Wu, Genghuang; Cai, Zhixiong; Chen, Xi

2015-03-01

In this study, a facile hydrothermal method was developed to synthesize Pt-on-Pd supported on reduced graphene oxide (Pt-on-Pd/RGO) hybrids. Because of the synergistic effect between Pt-on-Pd and RGO, the obtained Pt-on-Pd/RGO had superior peroxidase-mimic activities in H2O2 reduction and TMB oxidation. The reaction medium was optimized and a sensing approach for H2O2 was developed with a linear range from 0.98 to 130.7 μM of H2O2. In addition, the characteristic of electrocatalytic oxidation of methanol was investigated. The peak current density value, j(f), for the Pt-on-Pd/RGO hybrid (328 mA mg(Pt)(-1)) was about 1.85 fold higher than that of commercial Pt black (177 mA mg(Pt)(-1)) and, also, more durable electrocatalytic activity could be obtained. For the first time, the dual-functional Pt-on-Pd/RGO with peroxidase-mimic activity and an enhanced electrocatalytic oxidation characteristic was reported. Copyright © 2014 Elsevier B.V. All rights reserved.

A rational approach towards enhancing solar water splitting: a case study of Au-RGO/N-RGO-TiO2.

PubMed

Bharad, Pradnya A; Sivaranjani, Kumarsrinivasan; Gopinath, Chinnakonda S

2015-07-07

A rational approach was employed to enhance the solar water splitting (SWS) efficiency by systematically combining various important factors that helps to increase the photocatalytic activity. The rational approach includes four important parameters, namely, charge generation through simulated sunlight absorption, charge separation and diffusion, charge utilization through redox reaction, and the electronic integration of all of the above three factors. The complexity of the TiO2 based catalyst and its SWS activity was increased systematically by adding reduced graphene oxide (RGO) or N-doped RGO and/or nanogold. Au-N-RGO-TiO2 shows the maximum apparent quantum yield (AQY) of 2.46% with a H2 yield (525 μmol g(-1) h(-1)) from aqueous methanol, and overall water splitting activity (22 μmol g(-1) h(-1); AQY = 0.1%) without any sacrificial agent under one sun conditions. This exercise helps to understand the factors which help to enhance the SWS activity. Activity enhancement was observed when there is synergy among the components, especially the simulated sunlight absorption (or one sun conditions), charge separation/conduction and charge utilization. Electronic integration among the components provides the synergy for efficient solar light harvesting. In our opinion, the above synergy helps to increase the overall utilization of charge carriers towards the higher activity.

Facile synthesis of magnetic ZnFe2O4-reduced graphene oxide hybrid and its photo-Fenton-like behavior under visible iradiation.

PubMed

Yao, Yunjin; Qin, Jiacheng; Cai, Yunmu; Wei, Fengyu; Lu, Fang; Wang, Shaobin

2014-06-01

A magnetic ZnFe2O4-reduced graphene oxide (rGO) hybrid was successfully developed as a heterogeneous catalyst for photo-Fenton-like decolorization of various dyes using peroxymonosulfate (PMS) as an oxidant under visible light irradiation. Through an in situ chemical deposition and reduction, ZnFe2O4 nanoparticles (NPs) with an average size of 23.7 nm were anchored uniformly on rGO sheets to form a ZnFe2O4-rGO hybrid. The catalytic activities in oxidative decomposition of organic dyes were evaluated. The reaction kinetics, effect of ion species and strength, catalytic stability, degradation mechanism, as well as the roles of ZnFe2O4 and graphene were also studied. ZnFe2O4-rGO showed to be a promising photocatalyst with magnetism for the oxidative degradation of aqueous organic pollutants and simple separation. The combination of ZnFe2O4 NPs with graphene sheets leads to a much higher catalytic activity than pure ZnFe2O4. Graphene acted as not only a support and stabilizer for ZnFe2O4 to prevent them from aggregation, largely improving the charge separation in the hybrid material, but also a catalyst for activating PMS to produce sulfate radicals at the same time. The ZnFe2O4-rGO hybrid exhibited stable performance without losing activity after five successive runs.

Facile synthesis of ZnCo2O4/rGO nanocomposite for effective supercapacitor application

NASA Astrophysics Data System (ADS)

Mary, A. Juliet Christina; Bose, A. Chandra

2017-05-01

ZnCo2O4/rGO nanocompoite material gives the high specific capacitance value of 704.2 F/g at a current density of 0.75 A/g. rGO material provides the effective surface area for the composite which leads to better performance for supercapacitor application. Stability of ZnCo2O4/rGO nanocomposite was tested up to 400 cycles. ZnCo2O4/rGO nanocomposite is the suitable material for supercapacitor application.

Solution processable RGO-CdZnS composite for solar light responsive photocatalytic degradation of 4-Nitrophenol

NASA Astrophysics Data System (ADS)

Ibrahim, Sk; Chakraborty, Koushik; Pal, Tanusri; Ghosh, Surajit

2017-05-01

We report the one pot single step synthesis and characterization of solution processable reduced graphene oxide (RGO) - cadmium zinc sulfide (CdZnS) nanocomposite materials. The composite was characterized structurally and morphologically by XRD and TEM studies. The reduction of GO in RGO-CdZnS composite, was confirmed by XPS and Raman spectroscopy. The photocatalytic activity of the RGO-CdZnS composite was investigated towards the degradation of 4-Nitrophenol. A notable increase of photocatalytic efficiency of RGO-CdZnS compare to controlled CdZnS was observed. Here RGO plays a crucial role to efficient photo induced charge separation from the CdZnS, and decreases the electron-hole recombination probability and subsequently enhanced the photocatalytic activity of the RGO-CdZnS composite material under simulated solar light irradiation. This work highlights the potential application of RGO-based materials in the field of photocatalytic degradation of organic water pollutant.

Hybrid Tunnel Junction-Graphene Transparent Conductive Electrodes for Nitride Lateral Light Emitting Diodes.

PubMed

Wang, Liancheng; Cheng, Yan; Liu, Zhiqiang; Yi, Xiaoyan; Zhu, Hongwei; Wang, Guohong

2016-01-20

Graphene transparent conductive electrode (TCE) applications in nitride light emitting diodes (LEDs) are still limited by the large contact resistance and interface barrier between graphene and p-GaN. We propose a hybrid tunnel junction (TJ)-graphene TCE approach for nitride lateral LEDs theoretically and experimentally. Through simulation using commercial advanced physical models of semiconductor devices (APSYS), we found that low tunnel resistance can be achieved in the n(+)-GaN/u-InGaN/p(+)-GaN TJ, which has a lower tunneling barrier and an enhanced electric field due to the polarization effect. Graphene TCEs and hybrid graphene-TJ TCEs are then modeled. The designed hybrid TJ-graphene TCEs show sufficient current diffusion length (Ls), low introduced series resistance, and high transmittance. The assembled TJ LED with the triple-layer graphene (TLG) TCEs show comparable optoelectrical performance (3.99 V@20 mA, LOP = 10.8 mW) with the reference LED with ITO TCEs (3.36 V@20 mA, LOP = 12.6 mW). The experimental results further prove that the TJ-graphene structure can be successfully incorporated as TCEs for lateral nitride LEDs.

Graphene-assisted room-temperature synthesis of 2D nanostructured hybrid electrode materials: dramatic acceleration of the formation rate of 2D metal oxide nanoplates induced by reduced graphene oxide nanosheets.

PubMed

Sung, Da-Young; Gunjakar, Jayavant L; Kim, Tae Woo; Kim, In Young; Lee, Yu Ri; Hwang, Seong-Ju

2013-05-27

A new prompt room temperature synthetic route to 2D nanostructured metal oxide-graphene-hybrid electrode materials can be developed by the application of colloidal reduced graphene oxide (RGO) nanosheets as an efficient reaction accelerator for the synthesis of δ-MnO2 2D nanoplates. Whereas the synthesis of the 2D nanostructured δ-MnO2 at room temperature requires treating divalent manganese compounds with persulfate ions for at least 24 h, the addition of RGO nanosheet causes a dramatic shortening of synthesis time to 1 h, underscoring its effectiveness for the promotion of the formation of 2D nanostructured metal oxide. To the best of our knowledge, this is the first example of the accelerated synthesis of 2D nanostructured hybrid material induced by the RGO nanosheets. The observed acceleration of nanoplate formation upon the addition of RGO nanosheets is attributable to the enhancement of the oxidizing power of persulfate ions, the increase of the solubility of precursor MnCO3, and the promoted crystal growth of δ-MnO2 2D nanoplates. The resulting hybridization between RGO nanosheets and δ-MnO2 nanoplates is quite powerful not only in increasing the surface area of manganese oxide nanoplate but also in enhancing its electrochemical activity. Of prime importance is that the present δ-MnO2 -RGO nanocomposites show much superior electrode performance over most of 2D nanostructured manganate systems including a similar porous assembly of RGO and layered MnO2 nanosheets. This result underscores that the present RGO-assisted solution-based synthesis can provide a prompt and scalable method to produce nanostructured hybrid electrode materials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transparent Conducting Graphene Hybrid Films To Improve Electromagnetic Interference (EMI) Shielding Performance of Graphene.

PubMed

Ma, Limin; Lu, Zhengang; Tan, Jiubin; Liu, Jian; Ding, Xuemei; Black, Nicola; Li, Tianyi; Gallop, John; Hao, Ling

2017-10-04

Conducting graphene-based hybrids have attracted considerable attention in recent years for their scientific and technological significance in many applications. In this work, conductive graphene hybrid films, consisting of a metallic network fully encapsulated between monolayer graphene and quartz-glass substrate, were fabricated and characterized for their electromagnetic interference shielding capabilities. Experimental results show that by integration with a metallic network the sheet resistance of graphene was significantly suppressed from 813.27 to 5.53 Ω/sq with an optical transmittance at 91%. Consequently, the microwave shielding effectiveness (SE) exceeded 23.60 dB at the K u -band and 13.48 dB at the K a -band. The maximum SE value was 28.91 dB at 12 GHz. Compared with the SE of pristine monolayer graphene (3.46 dB), the SE of graphene hybrid film was enhanced by 25.45 dB (99.7% energy attenuation). At 94% optical transmittance, the sheet resistance was 20.67 Ω/sq and the maximum SE value was 20.86 dB at 12 GHz. Our results show that hybrid graphene films incorporate both high conductivity and superior electromagnetic shielding comparable to existing ITO shielding modalities. The combination of high conductivity and shielding along with the materials' earth-abundant nature, and facile large-scale fabrication, make these graphene hybrid films highly attractive for transparent EMI shielding.

Ultrasmall TiO2 Nanoparticles in Situ Growth on Graphene Hybrid as Superior Anode Material for Sodium/Lithium Ion Batteries.

PubMed

Liu, Huiqiao; Cao, Kangzhe; Xu, Xiaohong; Jiao, Lifang; Wang, Yijing; Yuan, Huatang

2015-06-03

To inhibit the aggregation of TiO2 nanoparticles and to improve the electrochemical kinetics of TiO2 electrode, a hybrid material of ultrasmall TiO2 nanoparticles in situ grown on rGO nanosheets was obtained by ultraphonic and reflux methods. The size of the TiO2 particles was controlled about 10 nm, and these particles were evenly distributed across the rGO nanosheets. When used for the anode of a sodium ion battery, the electrochemical performance of this hybrid TiO2@rGO was much improved. A capacity of 186.6 mAh g(-1) was obtained after 100 cycles at 0.1 A g(-1), and 112.2 mAh g(-1) could be maintained at 1.0 A g(-1), showing a high capacity and good rate capability. On the basis of the analysis of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the achieved excellent electrochemical performance was mainly attributed to the synergetic effect of well-dispersed ultrasmall TiO2 nanoparticles and conductive graphene network and the improved electrochemical kinetics. The superior electrochemical performance of this hybrid material on lithium storage further confirmed the positive effect of rGO.

Surface Modifier-Free Organic-Inorganic Hybridization To Produce Optically Transparent and Highly Refractive Bulk Materials Composed of Epoxy Resins and ZrO2 Nanoparticles.

PubMed

Enomoto, Kazushi; Kikuchi, Moriya; Narumi, Atsushi; Kawaguchi, Seigou

2018-04-25

Surface modifier-free hybridization of ZrO 2 nanoparticles (NPs) with epoxy-based polymers is demonstrated for the first time to afford highly transparent and refractive bulk materials. This is achieved by a unique and versatile hybridization via the one-pot direct phase transfer of ZrO 2 NPs from water to epoxy monomers without any aggregation followed by curing with anhydride. Three types of representative epoxy monomers, bisphenol A diglycidyl ether (BADGE), 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane carboxylate (CEL), and 1,3,5-tris(3-(oxiran-2-yl)propyl)-1,3,5-triazinane-2,4,6-trione (TEPIC), are used to produce transparent viscous dispersions. The resulting ZrO 2 NPs are thoroughly characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), and solid-state 13 C CP/MAS NMR measurements. The results from DLS and TEM analyses indicate nanodispersion of ZrO 2 into epoxy monomers as a continuous medium. A surface modification mechanism and the binding fashion during phase transfer are proposed based on the FT-IR and solid-state 13 C CP/MAS NMR measurements. Epoxy-based hybrid materials with high transparency and refractive index are successfully fabricated by heat curing or polymerizing a mixture of monomers containing epoxy-functionalized ZrO 2 NPs and methylhexahydrophthalic anhydride in the presence of a phosphoric catalyst. The TEM and small-angle X-ray scattering measurements of the hybrids show a nanodispersion of ZrO 2 in the epoxy networks. The refractive index at 594 nm ( n 594 ) increases up to 1.765 for BADGE-based hybrids, 1.667 for CEL-based hybrids, and 1.693 for TEPIC-based hybrids. Their refractive indices and Abbe's numbers are quantitatively described by the Lorentz-Lorenz effective medium expansion theory. Their transmissivity is also reasonably explained using Fresnel refraction, Rayleigh scattering, and the Lambert-Beer theories. This surface modifier-free hybridization

Enhanced photocatalytic performance of KNbO3(100)/reduced graphene oxide nanocomposites investigated using first-principles calculations: RGO reductivity effect

NASA Astrophysics Data System (ADS)

Zhang, Pan; Shen, Yanqing; Wu, Wenjing; Li, Jun; Zhou, Zhongxiang

2018-03-01

Although a number of various reduced graphene oxide (RGO)-based nanomaterials with enhanced photocatalytic performance have recently been characterized, the effect of RGO reductivity on their performance is still not clear. Herein, KNbO3(100) surface modification with three RGO sheets of different reductivity is investigated using first-principles calculations, revealing that increasing RGO reductivity enhances the photocatalytic performance of KNbO3(100)/RGO nanocomposites. In contrast to CeO2/RGO nanocomposites, the O atoms of RGO inhibit the photoactivity of KNbO3/RGO nanocomposites by restraining the effect of inducing a red shift of the corresponding photocatalytic absorption spectra by C 2p states. Increased RGO reductivity extends its absorption edge to the visible light region of the optical absorption and also promotes charge transfer from the KNbO3(100) surface to RGO sheets, in contrast to the behavior observed for g-C3N4/RGO composites. Overall, this work provides a reasonable explanation of controversial experimental results obtained previously, paving the way to the development of highly efficient RGO-based photocatalysts and promoting further photocatalytic applications of KNbO3/RGO nanocomposites.

Reduced Graphene Oxide-Hybridized Polymeric High-Internal Phase Emulsions for Highly Efficient Removal of Polycyclic Aromatic Hydrocarbons from Water Matrix.

PubMed

Huang, Yipeng; Zhang, Wenjuan; Ruan, Guihua; Li, Xianxian; Cong, Yongzheng; Du, Fuyou; Li, Jianping

2018-03-27

Reduced graphene oxide (RGO)-hybridized polymeric high-internal phase emulsions (RGO/polyHIPEs) with an open-cell structure and hydrophobicity have been successfully prepared using 2-ethylhexyl acrylate and ethylene glycol dimethacrylate as the monomer and the cross-linker, respectively. The adsorption mechanism and performance of this RGO/polyHIPEs to polycyclic aromatic hydrocarbons (PAHs) were investigated. Adsorption isotherms of PAHs on RGO/polyHIPEs show that the saturated adsorption capacity is 47.5 mg/g and the equilibrium time is 8 h. Cycling tests show that the adsorption capacity of RGO/polyHIPEs remains stable in 10 adsorption-desorption cycles without observable structure change in RGO/polyHIPEs. Moreover, the PAH residues in water samples after being purified by RGO/polyHIPEs are lower than the limit values in drinking water set by the European Food Safety Authority. These results demonstrate that the RGO/polyHIPEs have great potentiality in PAH removal and water purification.

Manganese-enriched electrochemistry of LiFePO4/RGO nanohybrid for aqueous energy storage

NASA Astrophysics Data System (ADS)

Rossouw, Claire A.; Raju, Kumar; Zheng, Haitao; Ozoemena, Kenneth I.

2017-07-01

Manganese-doped lithium iron phosphate (LFMP) integrated with reduced graphene oxide (RGO) has been prepared via microwave-assisted synthesis and investigated as lithium-ion energy storage system in aqueous Li2SO4 electrolyte. The doping of the LFP was achieved with a low-cost commercial electrolytic manganese oxide (EMD) precursor using a microwave-assisted solvothermal technique. When compared to the undoped counterpart (LFP/RGO), obtained under similar experimental conditions, the LFMP/RGO nanohybrid showed an improved electrochemical performance. The LFMP/RGO gave a maximum areal capacitance of ca. 39.48 mF cm-2, power density of 70.3 mW cm-2 and energy density of 8 mWh cm-2 compared to the values for the pristine complex (LFP/RGO); ca. 16.85 mF cm-2, 54.4 mW cm-2 and 4.8 mWh cm-2. In addition, when the two types of electrochemical storage systems were subjected to voltage-holding (floating) experiment for 50 h, LFMP/RGO maintained 98% capacitance retention while LFP/G maintained 94% capacitance retention. The findings in this work prove that Mn-doping is capable of enhancing the electrochemical performance of the LFP material for energy storage.

Improved efficiency of hybrid organic photovoltaics by pulsed laser sintering of silver nanowire network transparent electrode.

PubMed

Spechler, Joshua A; Nagamatsu, Ken A; Sturm, James C; Arnold, Craig B

2015-05-20

In this Research Article, we demonstrate pulsed laser processing of a silver nanowire network transparent conductor on top of an otherwise complete solar cell. The macroscopic pulsed laser irradiation serves to sinter nanowire-nanowire junctions on the nanoscale, leading to a much more conductive electrode. We fabricate hybrid silicon/organic heterojunction photovoltaic devices, which have ITO-free, solution processed, and laser processed transparent electrodes. Furthermore, devices which have high resistive losses show up to a 35% increase in power conversion efficiency after laser processing. We perform this study over a range of laser fluences, and a range of nanowire area coverage to investigate the sintering mechanism of nanowires inside of a device stack. The increase in device performance is modeled using a simple photovoltaic diode approach and compares favorably to the experimental data.

Studies on synthesis of reduced graphene oxide (RGO) via green route and its electrical property

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadhukhan, Sourav; Department of Chemistry, Budge Budge Institute of Technology, Nischintapur, Budge Budge, Kolkata 700137; Ghosh, Tapas Kumar

2016-07-15

Highlights: • RGO-1 and RGO-2 were synthesized by green method using different phytoextracts. • M. indica L., S. tuberosum L. phytoextracts act as reducing and stabilizing agents. • Conjugated structure of graphene is established following partial reduction of GO. • Electrical conductivities of RGO-1 and RGO-2 are higher than GO. - Abstract: An environmentally friendly method has been applied for the preparation of reduced graphene oxide (RGO). This method was developed by using polyphenols that contained a phytoextract of Mangifera indica L. along with Solanum tuberosum L. as reducing agents since they are non-toxic and naturally available. The phytoextracts usedmore » in the production of RGO was set between 60 and 70 °C. Graphene oxide (GO) was prepared by modified Hummer’s method as reported in earlier findings. Structural and morphological studies demonstrate that the part of the oxygen functionalities in GO can be removed by following green reduction. Characterizations of the resulting product have been done by X-ray diffraction, FTIR, UV–vis and Raman spectroscopy. FESEM, TEM, EDX spectrum, TGA, DLS and Zeta potential measurements of the samples have also been carried out to study the morphological, thermal and surface charge characteristics. Electrical conductivity was also measured to check the extent of reduction of GO to RGO.« less

Preparation and electromagnetic wave absorption of RGO/Cu nanocomposite

NASA Astrophysics Data System (ADS)

Zhang, Hui; Tian, Xingyou; Zhang, Xian; Li, Shikuo; Shen, Yuhua; Xie, Anjian

2017-09-01

We use a facile pyrolysis method to prepare reduced graphene oxide and copper nanocomposite (RGO/Cu) based on it. The product shows an outstanding wave absorption properties. The maximum reflection loss is up to-50.7 dB at 3.8 GHz. The reflection loss of-10 dB (90% power absorption) corresponds to a bandwidth of 11.2 GHz (3.4-14.6 GHz range) for the layer thickness of 2-5 mm. Therefore, it is suggested that the RGO/Cu nanocomposite is also a new kind of lightweight and high-performance EM wave absorbing material.

Synthesis and Characterization of Graphene/ITO Nanoparticle Hybrid Transparent Conducting Electrode

NASA Astrophysics Data System (ADS)

Hemasiri, Bastian Waduge Naveen Harindu; Kim, Jae-Kwan; Lee, Ji-Myon

2018-03-01

The combination of graphene with conductive nanoparticles, forming graphene-nanoparticle hybrid materials, offers a number of excellent properties for advanced engineering applications. A novel and simple method was developed to deposit 10 wt% tin-doped indium tin oxide (ITO) nanoparticles on graphene. The method involved a combination of a solution-based environmentally friendly electroless deposition approach and subsequent vacuum annealing. A stable organic-free solution of ITO was prepared from economical salts of In(NO3) 3 · H2O and SnCl4. The obtained ITO nanostructure exhibited a unique architecture, with uniformly dispersed 25-35 nm size ITO nanoparticles, containing only the crystallized In2O3 phase. The synthesized ITO nanoparticles-graphene hybrid exhibited very good and reproducible optical transparency in the visible range (more than 85%) and a 28.2% improvement in electrical conductivity relative to graphene synthesized by chemical vapor deposition. It was observed that the ITO nanoparticles affect the position of the Raman signal of graphene, in which the D, G, and 2D peaks were redshifted by 5.65, 5.69, and 9.74 cm-1, respectively, and the annealing conditions had no significant effect on the Raman signatures of graphene. [Figure not available: see fulltext.

Hierarchically structured transparent hybrid membranes by in situ growth of mesostructured organosilica in host polymer

NASA Astrophysics Data System (ADS)

Vallé, Karine; Belleville, Philippe; Pereira, Franck; Sanchez, Clément

2006-02-01

The elaborate performances characterizing natural materials result from functional hierarchical constructions at scales ranging from nanometres to millimetres, each construction allowing the material to fit the physical or chemical demands occurring at these different levels. Hierarchically structured materials start to demonstrate a high input in numerous promising applied domains such as sensors, catalysis, optics, fuel cells, smart biologic and cosmetic vectors. In particular, hierarchical hybrid materials permit the accommodation of a maximum of elementary functions in a small volume, thereby optimizing complementary possibilities and properties between inorganic and organic components. The reported strategies combine sol-gel chemistry, self-assembly routes using templates that tune the material's architecture and texture with the use of larger inorganic, organic or biological templates such as latex, organogelator-derived fibres, nanolithographic techniques or controlled phase separation. We propose an approach to forming transparent hierarchical hybrid functionalized membranes using in situ generation of mesostructured hybrid phases inside a non-porogenic hydrophobic polymeric host matrix. We demonstrate that the control of the multiple affinities existing between organic and inorganic components allows us to design the length-scale partitioning of hybrid nanomaterials with tuned functionalities and desirable size organization from ångström to centimetre. After functionalization of the mesoporous hybrid silica component, the resulting membranes have good ionic conductivity offering interesting perspectives for the design of solid electrolytes, fuel cells and other ion-transport microdevices.

Removal Enhancement of Basic Blue 41 BY RGO-TiO2 Nanocomposite Synthesized Using Pulsed Laser

NASA Astrophysics Data System (ADS)

Ghasemi, Fatemeh; Kimiagar, Salimeh; Shahbazi, Mozhgan; Vojoudi, Hossein

Graphene oxide (GO) and GO-TiO2 nanocomposite was produced then reduced under pulse laser irradiation (RGO-TiO2). Basic blue 41 (bb41) dye was removed from aqueous solutions by using RGO-TiO2 nanocomposites. The UV-Vis absorption and FTIR analysis were utilized to confirm the reduction of GO-TiO2 to RGO-TiO2. The results showed complete reduction of GO. X-ray diffraction (XRD), Raman spectra and scanning electron microscopy (SEM) analysis were applied to approve the RGO-TiO2 nanocomposite structure. The effect of pH on the bb41 removal by RGO-TiO2 was studied varying the pH from 1 to 11. The optimum pH and adsorbent dosage were found to be 9 and 0.2g/L with 98% efficiency, respectively. The calculated coefficients demonstrated that the Langmuir model was fixed to the experimental data. The results indicated that RGO-TiO2 could be engaged as an exceptional sorbent to remove bb41 dye which is in aqueous solution.

A flexible plasma-treated silver-nanowire electrode for organic light-emitting devices.

PubMed

Li, Jun; Tao, Ye; Chen, Shufen; Li, Huiying; Chen, Ping; Wei, Meng-Zhu; Wang, Hu; Li, Kun; Mazzeo, Marco; Duan, Yu

2017-11-28

Silver nanowires (AgNWs) are a promising candidate to replace indium tin oxide (ITO) as transparent electrode material. However, the loose contact at the junction of the AgNWs and residual surfactant polyvinylpyrrolidone (PVP) increase the sheet resistance of the AgNWs. In this paper, an argon (Ar) plasma treatment method is applied to pristine AgNWs to remove the PVP layer and enhance the contact between AgNWs. By adjusting the processing time, we obtained AgNWs with a sheet resistance of 7.2Ω/□ and a transmittance of 78% at 550 nm. To reduce the surface roughness of the AgNWs, a peel-off process was used to transfer the AgNWs to a flexible NOA63 substrate. Then, an OLED was fabricated with the plasma-treated AgNWs electrode as anode. The highest brightness (27000 cd/m 2 ) and current efficiency (11.8 cd/A) was achieved with a 30 nm thick light emitting layer of tris-(8-hydroxyquinoline) aluminum doped with 1% 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5 H,11H-(1)-benzopyropyrano(6,7-8-I,j)quinolizin-11-one. Compared to thermal annealing, the plasma-treated AgNW film has a lower sheet resistance, a shorter processing time, and a better hole-injection. Our results indicate that plasma treatment is an effective and efficient method to enhance the conductivity of AgNW films, and the plasma-treated AgNW electrode is suitable to manufacture flexible organic optoelectronic devices.

Effects of graphene oxide concentration on optical properties of ZnO/RGO nanocomposites and their application to photocurrent generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azarang, Majid, E-mail: azarangmajid@gmail.com, E-mail: azarang@phys.usb.ac.ir; Department of Physics, University of Sistan and Baluchestan, 98135-674 Zahedan; Shuhaimi, Ahmad

2014-08-28

The effects of different concentrations of graphene oxide (GO) on the structure and optical properties of ZnO nanoparticles (NPs) were investigated. The nanocomposites were synthesized via the sol-gel method in a gelatin medium. X-ray diffraction patterns (XRD) and Fourier transform infrared spectroscopy indicated that the GO sheets were reduced and changed to reduced GO (RGO) during the calcination of the nanocomposites at 400 °C. In addition, the XRD patterns of the NPs indicated a hexagonal (wurtzite) structure for all the products. Microscopic studies showed that the NPs were decorated and dispersed on the RGO sheets very well. However, these studies revealedmore » that the RGO concentration had an effect on the crystal growth process for the ZnO NPs. Furthermore, these studies showed that the NPs could be grown with a single crystal quality in an optimum RGO concentration. According to the XRD results that were obtained from pure ZnO NPs, the calcinations temperature was decreased by the RGO. UV–vis and room temperature photoluminescence studies showed that the optical properties of the ZnO/RGO nanocomposite were affected by the RGO concentration. Finally, the obtained ZnO/RGO nanocomposite was used to generate a photocurrent. Observations showed that the photocurrent intensity of the nanocomposite was significantly increased by increasing the RGO, with an optimum RGO concentration.« less

Emerging materials for transparent conductive electrodes and their applications in photovoltaics

NASA Astrophysics Data System (ADS)

Zhu, Zhaozhao

Clean and affordable energy, especially solar energy, is becoming more and more important as our annual total energy consumption keeps rising. However, to make solar energy more affordable and accessible, the cost for fabrication, transportation and assembly of all components need to be reduced. As a crucial component for solar cells, transparent conductive electrode (TCE) can determine the cost and performance. A light weight, easy-to-fabricate and cost-effective new generation TCE is thus needed. While indium-doped tin oxide (ITO) has been the most widely used material for commercial applications as TCEs, its cost has gone up due to the limited global supply of indium. This is not only due to the scarcity of the element itself, but also the massive production of various opto-electronic devices such as TVs, smartphones and tablets. In order to reduce the cost for fabricating large area solar cells, substitute materials for ITO should be developed. These materials should have similar optical transmittance in the visible wavelength range, as well as similar electrical conductivity (sheet resistance) to ITO. This work starts with synthesizing ITO-replacing nano-materials, such as copper nanowires (CuNWs), derivative zinc oxide (ZnO) thin films, reduced graphene oxide (rGO) and so on. Further, we applied various deposition techniques, including spin-coating, spray-coating, Mayer-rod coating, filtration and transferring, to coat transparent substrates with these materials in order to fabricate TCEs. We characterize these materials and analyze their electrical/optical properties as TCEs. Additionally, these fabricated single-material-based TCEs were tested in various lab conditions, and their shortcomings (instability, rigidity, etc.) were highlighted. In order to address these issues, we hybridized the different materials to combine their strengths and compared the properties to single-material based TCEs. The multiple hybridized TCEs have comparable optical

Impressive nonlinear optical response exhibited by Poly(vinylidene fluoride) (PVDF)/reduced graphene oxide (RGO) nanocomposite films

NASA Astrophysics Data System (ADS)

Sabira, K.; Saheeda, P.; Divyasree, M. C.; Jayalekshmi, S.

2017-12-01

In the present work, the nonlinear optical properties of free-standing films of Poly(vinylidene fluoride) (PVDF)/reduced graphene oxide (RGO) nanocomposite are investigated to assess their suitability as efficient optical limiters. The PVDF/RGO nanocomposite films are generated by mixing different concentrations of RGO as the filler, with PVDF, using solution casting method. The XRD and FTIR data of these nanocomposite films confirm the enhancement in the β phase of PVDF when RGO is added to PVDF, which is one of the prime factors, enhancing the nonlinear response of the nanocomposite. The open aperture and closed aperture Z-scan technique under nanosecond excitation (532 nm, 7 ns) is used to investigate the nonlinear optical characteristics of the PVDF/RGO nanocomposite films. These films are found to exhibit two photon absorption assisted optical non linearity in the nanosecond regime. The highlight of the present work is the observation of quite low values of the normalized transmittance and low optical limiting threshold power in free standing films of PVDF/RGO nanocomposite. These flexible, free-standing and stable nanocomposite films offer high application prospects in the design of efficient optical limiting devices of any desired size or shape.

Synthesis of CdS-decorated RGO nanocomposites by reflux condensation method and its improved photocatalytic activity

NASA Astrophysics Data System (ADS)

Meng, Nannan; Zhou, Yifeng; Nie, Wangyan; Chen, Pengpeng

2016-08-01

The cadmium sulfide nanoparticle-reduced graphene oxide (CdS/RGO) nanocomposite with intimate nano-interfacial contact was successfully prepared via a facile condensation process in dilute dimethylformamide (DMF) aqueous solution. Numerous CdS nanoparticles featuring a size of around 10 nm were homogeneously anchored on 2D nanosheets. During the formation of CdS/RGO nanocomposite, graphene oxide (GO) was transformed into RGO simultaneously. The solar-driven degradation of Rhodamine B (RhB) was conducted to detect the activity of the as-prepared CdS/RGO nanocomposite. Significantly, the photocatalytic activity of CdS/RGO nanocomposite was almost three times higher than that of pure CdS. The charge transfer and photogenerated active hydroxyl radicals (ṡOH) were investigated to study the mechanism of excellent photocatalytic property. The synthetic method provided a valuable opportunity to fabricate large-scale novel graphene-based materials with superior catalytic activity.

Controllable in situ synthesis of epsilon manganese dioxide hollow structure/RGO nanocomposites for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Lin, Mei; Chen, Bolei; Wu, Xiao; Qian, Jiasheng; Fei, Linfeng; Lu, Wei; Chan, Lai Wa Helen; Yuan, Jikang

2016-01-01

Well-organized epsilon-MnO2 hollow spheres/reduced graphene oxide (MnO2HS/RGO) composites have been successfully constructed via a facile and one-pot synthetic route. The ε-MnO2 hollow spheres with the diameter of ~500 nm were grown in situ with homogeneous distribution on both sides of graphene oxide (GO) sheets in aqueous suspensions. The formation mechanism of the MnO2HS/RGO composites has been systematically investigated, and a high specific capacitance and good cycling capability were achieved on using the composites as supercapacitors. The galvanostatic charge/discharge curves show a specific capacitance of 471.5 F g-1 at 0.8 A g-1. The hollow structures of ε-MnO2 and the crumpled RGO sheets can enhance the electroactive surface area and improve the electrical conductivity, thus further facilitating the charge transport. The MnO2HS/RGO composite exhibits a high capacitance of 272 F g-1 at 3 A g-1 (92% retention) even after 1000 cycles. The prominent electrochemical performance might be attributed to the combination of the pseudo-capacitance of the MnO2 nanospheres with a hollow structure and to the good electrical conductivity of the RGO sheets. This work explores a new concept in designing metal oxides/RGO composites as electrode materials.Well-organized epsilon-MnO2 hollow spheres/reduced graphene oxide (MnO2HS/RGO) composites have been successfully constructed via a facile and one-pot synthetic route. The ε-MnO2 hollow spheres with the diameter of ~500 nm were grown in situ with homogeneous distribution on both sides of graphene oxide (GO) sheets in aqueous suspensions. The formation mechanism of the MnO2HS/RGO composites has been systematically investigated, and a high specific capacitance and good cycling capability were achieved on using the composites as supercapacitors. The galvanostatic charge/discharge curves show a specific capacitance of 471.5 F g-1 at 0.8 A g-1. The hollow structures of ε-MnO2 and the crumpled RGO sheets can enhance the

Hole conduction pathways in transparent amorphous tin oxides

NASA Astrophysics Data System (ADS)

Wahila, Matthew; Lebens-Higgins, Zachary; Quackenbush, Nicholas; Piper, Louis; Butler, Keith; Hendon, Christopher; Walsh, Aron; Watson, Graeme

P-type transparent amorphous oxide semiconductors (TAOS) have yet to be sufficiently demonstrated or commercialized, severely limiting the possible device architecture of transparent and flexible oxide electronics. The lack of p-type amorphous oxide candidates mainly originates from the directional oxygen 2 p character of their topmost valence states. Previous attempts to create p-type oxides have involved hybridization of the O 2 p with metal orbitals, such as with CuAlO2 and its Cu 3 d - O 2 p hybridization. However, the highly directional nature of the utilized orbitals means that structural disorder inhibits hybridization and severely disrupts hole-conduction pathways. Crystalline stannous oxide (SnO) and other lone-pair active post-transition metal oxides can have reduced localization at the valence band edge due to complex hybridization between the O 2 p, metal p, and spherical metal s-orbitals. I will discuss our investigation of structural disorder in SnO. Using a combination of synchrotron spectroscopy, and atomistic calculations, our investigation elucidates the important interplay between atomistic and electronic structure in establishing continuous hole conduction pathways at the valence band edge of transparent amorphous oxides.

Hierarchical hybrid of Ni3N/N-doped reduced graphene oxide nanocomposite as a noble metal free catalyst for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Zhao, Qi; Li, Yingjun; Li, Yetong; Huang, Keke; Wang, Qin; Zhang, Jun

2017-04-01

Novel nickel nitride (Ni3N) nanoparticles supported on nitrogen-doped reduced graphene oxide nanosheets (N-RGOs) are synthesized via a facile strategy including hydrothermal and subsequent calcination methods, in which the reduced graphene oxide nanosheets (RGOs) are simultaneously doped with nitrogen species. By varying the content of the RGOs, a series of Ni3N/N-RGO nanocomposites are obtained. The Ni3N/N-RGO-30% hybrid nanocomposite exhibits superior catalytic activity towards oxygen reduction reaction (ORR) under alkaline condition (0.1 M KOH). Furthermore, this hybrid catalyst also demonstrates high tolerance to methanol poisoning. The RGO containing rich N confers the nanocomposite with large specific surface area and high electronic conduction ability, which can enhance the catalytic efficiency of Ni3N nanoparticles. The enhanced catalytic activity can be attributed to the synergistic effect between Ni3N and nitrogen doped reduced graphene oxide. In addition, the sufficient contact between Ni3N nanoparticles and the N-RGO nanosheets simultaneously promotes good nanoparticle dispersion and provides a consecutive activity sites to accelerate electron transport continuously, which further enhance the ORR performance. The Ni3N/N-RGO may be further an ideal candidate as efficient and inexpensive noble metal-free ORR electrocatalyst in fuel cells.

Electromagnetically induced transparency with hybrid silicon-plasmonic traveling-wave resonators

NASA Astrophysics Data System (ADS)

Ketzaki, Dimitra A.; Tsilipakos, Odysseas; Yioultsis, Traianos V.; Kriezis, Emmanouil E.

2013-09-01

Spectral filtering and electromagnetically induced transparency (EIT) with hybrid silicon-plasmonic traveling-wave resonators are theoretically investigated. The rigorous three-dimensional vector finite element method simulations are complemented with temporal coupled mode theory. We show that ring and disk resonators with sub-micron radii can efficiently filter the lightwave with minimal insertion loss and high quality factors (Q). It is shown that disk resonators feature reduced radiation losses and are thus advantageous. They exhibit unloaded quality factors as high as 1000 in the telecom spectral range, resulting in all-pass filtering components with sharp resonances. By cascading two slightly detuned resonators and providing an additional route for resonator interaction (i.e., a second bus waveguide), a response reminiscent of EIT is observed. The EIT transmission peak can be shaped by means of resonator detuning and interelement separation. Importantly, the respective Q can become higher than that of the single-resonator structure. Thus, the possibility of exploiting this peak in switching applications relying on the thermo-optic effect is, finally, assessed.

Control of electromagnetically induced transparency via a hybrid semiconductor quantum dot-vanadium dioxide nanoparticle system

NASA Astrophysics Data System (ADS)

Zamani, Naser; Hatef, Ali; Nadgaran, Hamid; Keshavarz, Alireza

2017-07-01

We numerically investigate the electromagnetically induced transparency (EIT) of a hybrid system consisting of a three-level quantum dot (QD) in the vicinity of vanadium dioxide nanoparticle (VO2NP). VO2NP has semiconductor and metallic phases where the transition between the two phases occurs around a critical temperature. When the QD-VO2NP hybrid system interacts with continuous wave laser fields in an infrared regime, it supports a coherent coupling of exciton-polariton and exciton-plasmon polariton in semiconductor and metal phases of VO2NP, respectively. In our calculations a filling fraction factor controls the VO2NP phase transition. A probe and control laser field configuration is studied for the hybrid system to measure the absorption of QD through the filling fraction factor manipulations. We show that for the VO2NP semiconductor phase and proper geometrical configuration, the absorption spectrum profile of the QD represents an EIT with two peaks and a clear minimum. These two peaks merge to one through the VO2NP phase transition to metal. We also show that the absorption spectrum profile is modified by different orientations of the laser fields with the axis of the QD-VO2NP hybrid system. The innovation in comparison to other research in the field is that robust variation in the absorption profile through EIT is due to the phase transition in VO2NP without any structural change in the QD-VO2NP hybrid system. Our results can be employed to design nanothermal sensors, optical nanoswitches, and energy transfer devices.

Easily Dispersible NiFe2O4/RGO Composite for Microwave Absorption Properties in the X-Band

NASA Astrophysics Data System (ADS)

Bateer, Buhe; Zhang, Jianjao; Zhang, Hongchen; Zhang, Xiaochen; Wang, Chunyan; Qi, Haiqun

2018-01-01

Composites with good dispersion and excellent microwave absorption properties have important applications. Therefore, an easily dispersible NiFe2O4/reduced graphene oxide (RGO) composite has been prepared conveniently through a simple hydrothermal method. Highly crystalline, small size (about 7 nm) monodispersed NiFe2O4 nanoparticles (NPs) are evenly distributed on the surface of RGO. The microwave absorbability revealed that the NiFe2O4/RGO composite exhibits excellent microwave absorption properties in the X-band (8-12 GHz), and the minimum reflection loss of the NiFe2O4/RGO composite is -27.7 dB at 9.2 GHz. The NiFe2O4/RGO composite has good dispersibility in nonpolar solvent, which facilitates the preparation of stable commercial microwave absorbing coatings. It can be a promising candidate for lightweight microwave absorption materials in many application fields.

Seed-free synthesis of 1D silver nanowires ink using clove oil (Syzygium Aromaticum) at room temperature.

PubMed

Jeevika, Alagan; Ravi Shankaran, Dhesingh

2015-11-15

Silver nanowires (AgNWs) have been demonstrated to be a promising next generation conducting material and an alternative to the traditional electrode (ITO) because of its high conductivity, transparency and stability. Generally, AgNWs are synthesized by chemical method (mainly polyol reduction method) at high temperature in the presence of exotic seeds. The present work aims at the green approach for preparation and characterization of 1D AgNWs ink using clove oil (Syzygium Aromaticum) at room temperature. AgNWs was prepared by green synthesis using clove oil as reducing as well as capping agent at room temperature. The obtained ink was purified, filtered and redissolved in methanol. The prepared AgNWs showed an absorption peaks at 350 and 387nm in the UV-vis spectrum due to transverse SPR mode of silver. From the HR-TEM analysis, it was observed that the AgNWs possess an average diameter and length of ∼39±0.01nm and ∼3μm, respectively. The obtained AgNWs are crystalline in nature and are arranged in a perfect crystal lattice orientation, which was confirmed from the selected area electron diffraction studies. Moreover, the X-ray diffraction analysis confirms the face centered cubic structure. The AgNWs coated glass substrate shows an electrical conductivity of ∼0.48×10(6)S/m. Copyright © 2015 Elsevier Inc. All rights reserved.

All solid-state V2O5-based flexible hybrid fiber supercapacitors

NASA Astrophysics Data System (ADS)

Li, Huan; He, Jin; Cao, Xin; Kang, Liping; He, Xuexia; Xu, Hua; Shi, Feng; Jiang, Ruibin; Lei, Zhibin; Liu, Zong-Huai

2017-12-01

Vanadium pentoxide/single-walled carbon nanotube (V2O5-SWCNT) hybrid fibers with good electrochemical performance and flexibility are firstly prepared by using wet-spinning method. V2O5 nanobelt suspension is obtained by mixing V2O5 bulk, 30% H2O2, H2O and followed by hydrothermally treating at 190 °C for 15 h. SWCNT suspension is suspended into V2O5 nanobelt suspension under vigorous stirring, the V2O5-SWCNT homogenous suspension is obtained. It is injected into a coagulation bath composed of 5 wt % CaCl2 ethanol-water solution using syringe pump, V2O5-SWCNT hybrid fibers are prepared by washing with deionized water and drying at room temperature. Reduced graphene oxide (RGO)-SWCNT hybrid fibers are also prepared by the similar wet-spinning approach and followed by reducing GO-SWCNT hybrid fibers in an aqueous solution of hydriodic acid. All solid-state asymmetric V2O5/SWCNT//RGO/SWCNT fiber supercapacitors are assembled with V2O5-SWCNT fiber as positive electrode and RGO-SWCNT fiber as negative electrode by using PVA-H3PO4 as gel electrolyte. The assembled device not only shows maximum volumetric energy density of 1.95 mW h cm-3 at a volumetric power density of 7.5 mW cm-3, superior rate performance and cycling stability, but also exhibits remarkable flexibility to tolerate long-term and repeated bending. This work will open a new application filed of V2O5-based fibers in wearable energy storage devices.

Development of high energy density supercapacitor through hydrothermal synthesis of RGO/nano-structured cobalt sulphide composites

NASA Astrophysics Data System (ADS)

Jana, Milan; Saha, Sanjit; Samanta, Pranab; Murmu, Naresh Chandra; Kim, Nam Hoon; Kuila, Tapas; Lee, Joong Hee

2015-02-01

Co9S8/reduced graphene oxide (RGO) composites were prepared on nickel foam substrate through hydrothermal reaction and used directly as supercapacitor electrode. The field emission scanning electron microscopy analysis of the composites showed the formation of Co9S8 nano-rods on the RGO surfaces. The average crystal size of the Co9S8 nano rods grown on the RGO sheets were ˜25-36 nm as calculated from x-ray diffraction analysis. The reduction of graphene oxide (GO) was confirmed by Raman and x-ray photoelectron spectroscopy analysis. The electrical conductivity of the Co9S8/RGO composite was recorded as 1690 S m-1 at room temperature, which is much higher than that of pure GO further confirming the hydrothermal reduction of GO. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy were investigated to check the electrochemical performances of the Co9S8/RGO composites. The Co9S8/RGO composites supported on nickel foam showed very high specific capacitance (Sc)(1349 F g-1 at a current density of 2.2 A g-1), energy density (68.6 W h kg-1) and power density (1319 W kg-1) in 6 M KOH electrolyte. The retention in Sc of the composite electrode was found to be ˜96% after 1000 charge-discharge cycles.

Fabrication of flexible silver nanowire conductive films and transmittance improvement based on moth-eye nanostructure array

NASA Astrophysics Data System (ADS)

Zhang, Chengpeng; Zhu, Yuwen; Yi, Peiyun; Peng, Linfa; Lai, Xinmin

2017-07-01

Transparent conductive electrodes (TCEs) are widely used in optoelectronic devices, such as touch screens, liquid-crystal displays and light-emitting diodes. To date, the material of the most commonly used TCEs was indium-tin oxide (ITO), which had several intrinsic drawbacks that limited its applications in the long term, including relatively high material cost and brittleness. Silver nanowire (AgNW), as one of the alternative materials for ITO TCEs, has already gained much attention all over the world. In this paper, we reported a facile method to greatly enhance the transmittance of the AgNW TCEs without reducing the electrical conductivity based on moth-eye nanostructures, and the moth-eye nanostructures were fabricated by using a roll-to-roll ultraviolet nanoimprint lithography process. Besides, the effects of mechanical pressure and bending on the moth-eye nanostructure layer were also investigated. In the research, the optical transmittance of the flexible AgNW TCEs was enhanced from 81.3% to 86.0% by attaching moth-eye nanostructures onto the other side of the flexible polyethylene terephthalate substrate while the electrical conductivity of the AgNW TCEs was not sacrificed. This research can provide a direction for the cost-effective fabrication of moth-eye nanostructures and the transmittance improvement of the flexible transparent electrodes.

Enhanced electrocatalytic activity of reduced graphene oxide-Os nanoparticle hybrid films obtained at a liquid/liquid interface

NASA Astrophysics Data System (ADS)

Bramhaiah, K.; Pandey, Indu; Singh, Vidya N.; Kavitha, C.; John, Neena S.

2018-03-01

Hybrid films of reduced graphene oxide-osmium nanoparticles (rGO-Os NPs) synthesized at a liquid/liquid interface are explored for their electrocatalytic activity towards the oxidation of rhodamine B (RhB), a popular colourant found in textile industry effluents and a non-permitted food colour. The free-standing nature of the films enables them to be lifted directly on to electrodes without the aid of any binders. The films consist of aggregates of ultra-small Os NPs interspersed with rGO layers. The hybrid film exhibits enhanced RhB oxidation when compared to its constituents arising from the synergic effect between rGO and Os NPs, Os contributing to electrocatalysis and rGO contributing to high surface area and conductance as well as stabilization of Os nanoparticles. The electrochemical sensor based on rGO-Os NP hybrid film on pencil graphite electrode shows a remarkable performance for the quantitative detection of RhB with a linear variation in a wide range of concentrations, 4-1300 ppb (8.3 nM-2.71 μM). The modified electrode presents good stability over more than 6 months, reproducibility and anti-interference capability. The use of developed sensor for adequate detection of RhB in real samples such as food samples and pen markers is also demonstrated.

RGO/AuNR/HA-5FU nanocomposite with multi-stage release behavior and efficient antitumor activity for synergistic therapy.

PubMed

Yang, Ying; Wang, Yunlong; Zhu, Manzhou; Chen, Yan; Xiao, Yazhong; Shen, Yuhua; Xie, Anjian

2017-05-02

A reduced graphene oxide (RGO)/gold nanorod (AuNR)/hydroxyapatite (HA) nanocomposite was designed and successfully synthesized for the first time. An anticancer drug, 5-fluorouracil (5FU), was chosen as a model drug to be loaded in RGO/AuNR/HA. The fabricated RGO/AuNR/HA-5FU showed robust, selective targeting and penetrating efficiency against HeLa cells due to the good compatibility and nontoxicity of HA, and showed excellent synergetic antitumor effects through combined chemotherapy (CT) by 5FU and photothermal therapy (PTT) by both RGO and AuNRs under near-infrared (NIR) laser irradiation. More importantly, this synergistic dual therapy based on RGO/AuNR/HA can also minimize side effects in normal cells and exhibits greater antitumor activity because of a multi-stage drug release ability triggered by the pH sensitivity of HA in the first stage and the combined photothermal conversion capabilities of RGO and AuNRs by means of the NIR laser irradiation in the second stage. This study suggests that the novel RGO/AuNR/HA multi-stage drug delivery system may represent a promising potential application of multifunctional composite materials in the biomedical field.

High Performance of PEDOT:PSS/n-Si Solar Cells Based on Textured Surface with AgNWs Electrodes

NASA Astrophysics Data System (ADS)

Jiang, Xiangyu; Zhang, Pengbo; Zhang, Juan; Wang, Jilei; Li, Gaofei; Fang, Xiaohong; Yang, Liyou; Chen, Xiaoyuan

2018-02-01

Hybrid heterojunction solar cells (HHSCs) have gained extensive research and attention due to simple device structure and low-cost technological processes. Here, HHSCs are presented based on a highly transparent conductive polymer poly(3,4ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) directly spin-coated on an n-type crystalline silicon with microscale surface textures, which are prepared by traditional chemical etching. We have studied interface properties between PEDOT:PSS and textured n-Si by varying coating conditions. Final power conversion efficiency (PCE) could arrive at 8.54% by these simple solution-based fabrication processes. The high conversion efficiency is attributed to the fully conformal contact between PEDOT:PSS film and textured silicon. Furthermore, the reflectance of the PEDOT:PSS layer on textured surface is analyzed by changing film thickness. In order to improve the performance of the device, silver nanowires were employed as electrodes because of its better optical transmittance and electrical conductivity. The highest PCE of 11.07% was achieved which displayed a 29.6% enhancement compared with traditional silver electrodes. These findings imply that the combination of PEDOT:PSS film and silver nanowire transparent electrodes pave a promising way for realizing high-efficiency and low-cost solar cells.

High Performance of PEDOT:PSS/n-Si Solar Cells Based on Textured Surface with AgNWs Electrodes.

PubMed

Jiang, Xiangyu; Zhang, Pengbo; Zhang, Juan; Wang, Jilei; Li, Gaofei; Fang, Xiaohong; Yang, Liyou; Chen, Xiaoyuan

2018-02-14

Hybrid heterojunction solar cells (HHSCs) have gained extensive research and attention due to simple device structure and low-cost technological processes. Here, HHSCs are presented based on a highly transparent conductive polymer poly(3,4ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) directly spin-coated on an n-type crystalline silicon with microscale surface textures, which are prepared by traditional chemical etching. We have studied interface properties between PEDOT:PSS and textured n-Si by varying coating conditions. Final power conversion efficiency (PCE) could arrive at 8.54% by these simple solution-based fabrication processes. The high conversion efficiency is attributed to the fully conformal contact between PEDOT:PSS film and textured silicon. Furthermore, the reflectance of the PEDOT:PSS layer on textured surface is analyzed by changing film thickness. In order to improve the performance of the device, silver nanowires were employed as electrodes because of its better optical transmittance and electrical conductivity. The highest PCE of 11.07% was achieved which displayed a 29.6% enhancement compared with traditional silver electrodes. These findings imply that the combination of PEDOT:PSS film and silver nanowire transparent electrodes pave a promising way for realizing high-efficiency and low-cost solar cells.

Hybrid Reduced Graphene Oxide Nanosheet Supported Mn-Ni-Co Ternary Oxides for Aqueous Asymmetric Supercapacitors.

PubMed

Wu, Chun; Cai, Junjie; Zhu, Ying; Zhang, Kaili

2017-06-07

Hybrid reduced graphene oxide (RGO) nanosheet supported Mn-Ni-Co ternary oxides (MNCO) are prepared through a facile coprecipitation reaction with a subsequent calcination process as electrodes for supercapacitors. Electrochemical measurements prove that RGO can significantly improve the supercapacitive behaviors, compared with the pure MNCO electrode. A high specific capacity of 646.1 C g -1 at 1 A g -1 can be achieved and about 89.6% of the capacity can be remained at 30 A g -1 relative to that of the low-current capacity, indicating attractive rate capability of the RGO-MNCO electrode. Moreover, an asymmetric supercapacitor (ASC) device is fabricated with nitrogen-enriched RGO as the negative electrode and the synthesized RGO-MNCO as the positive electrode. Electrochemical performances investigated at different potential range reveal that the ASC device presents excellent capacitive behavior and reversibility. A maximum energy density of 35.6 Wh kg -1 at power density of 699.9 W kg -1 can be delivered. Furthermore, stable cycle capability with 100% Coulombic efficiency and 77.2% the capacitance retention is also achieved after 10000 cycles. The achieved outstanding electrochemical properties indicate that the obtained RGO-MNCO electrode materials are fairly ideal for progressive supercapacitors.

Synthesis of dendritic platinum nanoparticles/lucigenin/reduced graphene oxide hybrid with chemiluminescence activity.

PubMed

He, Yi; Cui, Hua

2012-04-16

Multifunctional hybrid: A dendritic platinum nanoparticle/lucigenin/reduced graphene oxide (RGO) hybrid with chemiluminescence (CL) activity was prepared for the first time by using lucigenin as a linker through simultaneous reduction of H(2) PtCl(4) and a lucigenin-functionalized graphene oxide composite by sodium borohydride (see scheme). The hybrid may have potential applications as a CL sensor, in catalysis, energy conversion, and opto-electronic systems. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sequential entrapping of Li and S in a conductivity cage of N-doped reduced graphene oxide supercapacitor derived from silk cocoon: a hybrid Li-S-silk supercapacitor

NASA Astrophysics Data System (ADS)

Jangir, Himanshi; Pandey, Mohit; Jha, Rishabh; Dubey, Amarish; Verma, Shourya; Philip, Deepu; Sarkar, Sabyasachi; Das, Mainak

2018-02-01

Li and S compounds are currently exploited for their applications in battery industry. Here, we discovered that Li-S compounds exhibit supercapacitor like properties in a context-dependent manner viz., when Li and S atoms are entrapped in a conductivity cage of N-doped reduced graphene oxide (ND-RGO) supercapacitor derived from silk cocoon, it resulted in the formation of a superior hybrid Li-S-silk (ND-RGO-Li-S) supercapacitor. Interestingly, ND-RGO-Li-S proves to be a better supercapacitor than ND-RGO alone. Electrochemical properties of ND-RGO versus ND-RGO-Li-S indicated that the later has higher capacitance ( 10.72%), lower resistance ( 2.98%), and higher time constant or relaxation time ( 7.52%). Thus, in one of the first attempts, caging Li and S in ND-RGO supercapacitor matrix offers a new role for Li-S, as an improved supercapacitor, unlike its current application as a battery.

2D Hybrid Nanomaterials for Selective Detection of NO2 and SO2 Using "Light On and Off" Strategy.

PubMed

Chen, Aimin; Liu, Rui; Peng, Xiao; Chen, Qiaofen; Wu, Jianmin

2017-10-25

In order to distinguish NO 2 and SO 2 gas with one sensor, we designed a paper chip assembled with a 2D g-C 3 N 4 /rGO stacking hybrid fabricated via a layer-by-layer self-assembly approach. The g-C 3 N 4 /rGO hybrid exhibited a remarkable photoelectric property due to the construction of a van der Waals heterostructure. For the first time, we have been able to selectively detect NO 2 and SO 2 gas using a "light on and off" strategy. Under the "light off" condition, the g-C 3 N 4 /rGO sensor exhibited a p-type semiconducting behavior with a low detection limit of 100 ppb of NO 2 , but with no response toward SO 2 . In contrast, the sensor showed n-type semiconducting behavior which could detect SO 2 at concentration as low as 2 ppm under UV light irradiation. The effective electron transfer among the 2D structure of g-C 3 N 4 and rGO nanosheets as well as highly porous structures could play an important role in gas sensing. The different sensing mechanisms at "light on and off" circumstances were also investigated in detail.

Transparent anti-stain coatings with good thermal and mechanical properties based on polyimide-silica nanohybrids.

PubMed

Choi, Myeon-Cheon; Sung, Giju; Nagappan, Saravanan; Han, Mi-Jeong; Ha, Chang-Sik

2012-07-01

In this work, we synthesized polyimide/silica hybrid materials via sol-gel method using a fluorinated poly(amic acid) silane precursor and a variety of perfluorosilane contents. We studied the influence of a hybrid coating film with the following characteristics; hydrophobicity, oleophobicity, optical transparency, and surface hardness of the coating films. The hybrid coatings with the fluorosilane contents up to 10 wt% are optically transparent and present good thermal stability with a degradation temperature of > 500 degrees C as well as a glass transition of > 300 degrees C. Both water contact angle and oil contact angle increase rapidly with introducing small amount of the fluorosilane in the hybrids and reaches the maximum of 115 degrees and 61 degrees, respectively. The hardness of the hybrid coatings increases up to 5H with an increase of the FTES content in the hybrids. These colorless, transparent, and thermally stable hybrid materials could be suitable for applications as anti-stain coatings.

The reduction of graphene oxide by zinc powder to produce a zinc oxide-reduced graphene oxide hybrid and its superior photocatalytic activity

NASA Astrophysics Data System (ADS)

Sarkar, Sanjit; Basak, Durga

2013-03-01

We have synthesized for the first time ZnO/rGO hybrids from metal zinc and GO using hydrothermal technique without adding further reducing agent. The photocatalytic property of ZnO-rGO reveals that the hybrid for 50 mg of GO has the highest activity, causing a 94% degradation of methyl orange compared to 70% by only ZnO. The consistent quenching and a gradual decrease in the decay life time of the emission at ˜500 nm as the rGO content increases indicates the interfacial charge transfer process between ZnO and rGO by the defect states responsible for green emission.

Electrochemical investigation of MoTe2/rGO composite materials for sodium-ion battery application

NASA Astrophysics Data System (ADS)

Panda, Manas Ranjan; Anish Raj, K.; Sarkar, Ananta; Bao, Qiaoliang; Mitra, Sagar

2018-05-01

2D layered materials are found to be promising anode materials for renewable energy storage devices like sodium and Li-ion batteries and have become attractive options due to their high specific capacity, abundance and low cost. In this work, we synthesized 2D MoTe2 layers embedded in reduced graphene oxide (rGO) anode material for sodium-ion battery applications. 2D MoTe2 was prepared by a solid-state reaction in vacuum at a temperature of 800 °C. The prepared composite material MoTe2/rGO showed excellent electrochemical performance against the sodium metal. The discharge capacity of MoTe2/rGO was observed to be 280 mAh g-1 at a current rate of 1.0 A g-1 for 100 cycles. rGO plays an important role in embedding the MoTe2 structure, thus improving the electrical and mechanical properties, leading to a superior cycling stability and excellent electrochemical performances of MoTe2 for sodium-ion battery applications.

Toward High Performance 2D/2D Hybrid Photocatalyst by Electrostatic Assembly of Rationally Modified Carbon Nitride on Reduced Graphene Oxide

NASA Astrophysics Data System (ADS)

Chen, Jian; Xu, Xiaochan; Li, Tao; Pandiselvi, Kannusamy; Wang, Jingyu

2016-11-01

Efficient metal-free visible photocatalysts with high stability are highly desired for sufficient utilization of solar energy. In this work, the popular carbon nitride (CN) photocatalyst is rationally modified by acid exfoliation of molecular grafted CN, achieving improved visible-light utilization and charge carriers mobility. Moreover, the modification process tuned the surface electrical property of CN, which enabled it to be readily coupled with the oppositely charged graphene oxide during the following photo-assisted electrostatic assembly. Detailed characterizations indicate the formation of well-contacted 2D/2D heterostructure with strong interfacial interaction between the modified CN nanosheets (CNX-NSs) and reduced graphene oxide (RGO). The optimized hybrid (with a RGO ratio of 20%) exhibits the best photocatalytic performance toward MB degradation, which is almost 12.5 and 7.0 times of CN under full spectrum and visible-light irradiation, respectively. In addition, the hybrid exhibits high stability after five successive cycles with no obvious change in efficiency. Unlike pure CNX-NSs, the dye decomposition mostly depends on the H2O2 generation by a two-electron process due to the electron reservoir property of RGO. Thus the enhancement in photocatalytic activity could be ascribed to the improved light utilization and increased charge transfer ability across the interface of CNX-NSs/RGO heterostructure.

Photocatalytic properties of amine functionalized Bi2Sn2O7/rGO nanocomposites

NASA Astrophysics Data System (ADS)

Gnanamoorthy, G.; Muthamizh, S.; Sureshbabu, K.; Munusamy, S.; Padmanaban, A.; Kaaviya, A.; Nagarajan, R.; Stephen, A.; Narayanan, V.

2018-07-01

The binary metal oxide nanomaterials are having applications in various fields like sensors, optics, electrocatalyst and photocatalyst so on. Bi2Sn2O7 with pyrochlore structure is having low band gap energy; hence it is utilized in battery storage and gas sensor applications. In the present work, we have made an attempt to synthesis amine-functionalized Bi2Sn2O7/rGO nanocomposites by a thermal decomposition method and in-situ method; the synthesized nanocomposites were confirmed by XRD, FT-IR and Raman analysis. The AF-Bi2Sn2O7/rGO nanocomposites morphology was confirmed by FE-SEM along with EDX spectroscopy, we obtained different flowers and nest-like morphology. The pure and composite material band gap energy is decreases from 2.6 eV to 1.6 eV. All three nanomaterials Bi2Sn2O7, AF-Bi2Sn2O7, AF-Bi2Sn2O7/rGO nanocomposites (AF-amine functionalized) were utilized for the photocatalytic degradation of methylene blue dye under visible light irradiation. AF-Bi2Sn2O7/rGO nanocomposite showed an excellent photocatalytic activity than pure Bi2Sn2O7 and AF- Bi2Sn2O7.

Understanding the Effects of NaCl, NaBr and Their Mixtures on Silver Nanowire Nucleation and Growth in Terms of the Distribution of Electron Traps in Silver Halide Crystals

PubMed Central

Rui, Yunjun; Zhao, Weiliang; Zhu, Dewei; Wang, Hengyu; Song, Guangliang; Swihart, Mark T.; Wan, Neng; Gu, Dawei; Tang, Xiaobing; Yang, Ying; Zhang, Tianyou

2018-01-01

In recent years, many research groups have synthesized ultra-thin silver nanowires (AgNWs) with diameters below 30 nm by employing Cl− and Br− simultaneously in the polyol process. However, the yield of AgNWs in this method was low, due to the production of Ag nanoparticles (AgNPs) as an unwanted byproduct, especially in the case of high Br− concentration. Here, we investigated the roles of Cl− and Br− in the preparation of AgNWs and then synthesized high aspect ratio (up to 2100) AgNWs in high yield (>85% AgNWs) using a Cl− and Br− co-mediated method. We found that multiply-twinned particles (MTPs) with different critical sizes were formed and grew into AgNWs, accompanied by a small and large amount of AgNPs for the NaCl and NaBr additives, respectively. For the first time, we propose that the growth of AgNWs of different diameters and yields can be understood based on the electron trap distribution (ETD) of the silver halide crystals. For the case of Cl− and Br− co-additives, a mixed silver halide crystal of AgBr1−xClx was formed, rather than the AgBr/AgCl mixture reported previously. In this type of crystal, the ETD is uniform, which is beneficial for the synthesis of AgNWs with small diameter (30~40 nm) and high aspect ratio. AgNW transparent electrodes were prepared in air by rod coating. A sheet resistance of 48 Ω/sq and transmittance of 95% at 550 nm were obtained without any post-treatment. PMID:29538281

Novel Flexible Transparent Conductive Films with Enhanced Chemical and Electromechanical Sustainability: TiO2 Nanosheet-Ag Nanowire Hybrid.

PubMed

Sohn, Hiesang; Kim, Seyun; Shin, Weonho; Lee, Jong Min; Lee, Hyangsook; Yun, Dong-Jin; Moon, Kyoung-Seok; Han, In Taek; Kwak, Chan; Hwang, Seong-Ju

2018-01-24

Flexible transparent conductive films (TCFs) of TiO 2 nanosheet (TiO 2 NS) and silver nanowire (Ag NW) network hybrid were prepared through a simple and scalable solution-based process. The as-formed TiO 2 NS-Ag NW hybrid TCF shows a high optical transmittance (TT: 97% (90.2% including plastic substrate)) and low sheet resistance (R s : 40 Ω/sq). In addition, the TiO 2 NS-Ag NW hybrid TCF exhibits a long-time chemical/aging and electromechanical stability. As for the chemical/aging stability, the hybrid TCF of Ag NW and TiO 2 NS reveals a retained initial conductivity (ΔR s /R s < 1%) under ambient oxidant gas over a month, superior to that of bare Ag NW (ΔR s /R s > 4000%) or RuO 2 NS-Ag NW hybrid (ΔR s /R s > 200%). As corroborated by the density functional theory simulation, the superb chemical stability of TiO 2 NS-Ag NW hybrid is attributable to the unique role of TiO 2 NS as a barrier, which prevents Ag NW's chemical corrosion via the attenuated adsorption of sulfidation molecules (H 2 S) on TiO 2 NS. With respect to the electromechanical stability, in contrast to Ag NWs (ΔR/R 0 ∼ 152.9%), our hybrid TCF shows a limited increment of fractional resistivity (ΔR/R 0 ∼ 14.4%) after 200 000 cycles of the 1R bending test (strain: 6.7%) owing to mechanically welded Ag NW networks by TiO 2 NS. Overall, our unique hybrid of TiO 2 NS and Ag NW exhibits excellent electrical/optical properties and reliable chemical/electromechanical stabilities.

Extremely flexible, transparent, and strain-sensitive electroluminescent device based on ZnS:Cu-polyvinyl butyral composite and silver nanowires

NASA Astrophysics Data System (ADS)

Jun, Sungwoo; Kim, Youngmin; Ju, Byeong-Kwon; Kim, Jong-Woong

2018-01-01

A multifunctional alternate current electroluminescent device (ACEL) was achieved by compositing ZnS:Cu particles in polyvinyl butyral (PVB) with two layers of percolated silver nanowire (AgNW) electrodes. The strong hydrogen bonding interactions and entanglement of PVB chains considerably strengthened the PVB, and thus, the cured mixture of ZnS:Cu particles and freestanding PVB required no additional support. The device was fabricated by embedding AgNWs on both sides of the ZnS:Cu-PVB composite film using an inverted layer process and intense-pulsed-light treatment. The strong affinity of PVB to the polyvinyl pyrrolidone (PVP) layer, which capped the AgNWs, mechanically stabilized the device to such an extent that it could resist 10,000 bending cycles under a curvature radius of 500 μm. Using AgNW networks in both the top and bottom electrodes made a double-sided light-emitting device that could be applied to wearable lightings or flexible digital signage. The capacitance formed in the device sensitively varied with the applied bending and unfolding, thus demonstrating that the device can also be used as a deformation sensor.

Recent advances of flexible hybrid perovskite solar cells

NASA Astrophysics Data System (ADS)

Shin, Dong Hee; Heo, Jin Hyuck; Im, Sang Hyuk

2017-11-01

Recently, hybrid perovskite solar cells have attracted great interest because they can be fabricated to low cost, flexible, and highly efficient solar cells. Here, we introduced recent advances of flexible hybrid perovskite solar cells. We introduced research background of flexible perovskite solar cells in introduction part. Then we composed the main body to i) structure and properties of hybrid perovskite solar cells, ii) why flexible hybrid perovskite solar cells are important?, iii) transparent conducting oxide (TCO) based flexible hybrid perovskite solar cells, and iv) TCO-free transparent conducting electrode (TCE) based flexible hybrid perovskite solar cells. Finally, we summarized research outlook of flexible hybrid perovskite solar cells.

Broadband telecom transparency of semiconductor-coated metal nanowires: more transparent than glass.

PubMed

Paniagua-Domínguez, R; Abujetas, D R; Froufe-Pérez, L S; Sáenz, J J; Sánchez-Gil, J A

2013-09-23

Metallic nanowires (NW) coated with a high permittivity dielectric are proposed as means to strongly reduce the light scattering of the conducting NW, rendering them transparent at infrared wavelengths of interest in telecommunications. Based on a simple, universal law derived from electrostatics arguments, we find appropriate parameters to reduce the scattering efficiency of hybrid metal-dielectric NW by up to three orders of magnitude as compared with the scattering efficiency of the homogeneous metallic NW. We show that metal@dielectric structures are much more robust against fabrication imperfections than analogous dielectric@metal ones. The bandwidth of the transparent region entirely covers the near IR telecommunications range. Although this effect is optimum at normal incidence and for a given polarization, rigorous theoretical and numerical calculations reveal that transparency is robust against changes in polarization and angle of incidence, and also holds for relatively dense periodic or random arrangements. A wealth of applications based on metal-NWs may benefit from such invisibility.

Transparent and High Refractive Index Thermoplastic Polymer Glasses Using Evaporative Ligand Exchange of Hybrid Particle Fillers.

PubMed

Wang, Zongyu; Lu, Zhao; Mahoney, Clare; Yan, Jiajun; Ferebee, Rachel; Luo, Danli; Matyjaszewski, Krzysztof; Bockstaller, Michael R

2017-03-01

Development of high refractive index glasses on the basis of commodity polymer thermoplastics presents an important requisite to further advancement of technologies ranging from energy efficient lighting to cost efficient photonics. This contribution presents a novel particle dispersion strategy that enables uniform dispersion of zinc oxide (ZnO) particles in a poly(methyl methacrylate) (PMMA) matrix to facilitate hybrid glasses with inorganic content exceeding 25% by weight, optical transparency in excess of 0.8/mm, and a refractive index greater than 1.64 in the visible wavelength range. The method is based on the application of evaporative ligand exchange to synthesize poly(styrene-r-acrylonitrile) (PSAN)-tethered zinc oxide (ZnO) particle fillers. Favorable filler-matrix interactions are shown to enable the synthesis of isomorphous blends with high molecular PMMA that exhibit improved thermomechanical stability compared to that of the pristine PMMA matrix. The concurrent realization of high refractive index and optical transparency in polymer glasses by modification of a thermoplastic commodity polymer could present a viable alternative to expensive specialty polymers in applications where high costs or demands for thermomechanical stability and/or UV resistance prohibit the application of specialty polymer solutions.

Noble metal-free RGO/TiO2 composite nanofiber with enhanced photocatalytic H2-production performance

NASA Astrophysics Data System (ADS)

Xu, Difa; Li, Lingling; He, Rongan; Qi, Lifang; Zhang, Liuyang; Cheng, Bei

2018-03-01

1D reduced graphene oxide (RGO)/TiO2 nanocomposite fibers were fabricated by a facile two-step method. These samples demonstrated high photocatalytic H2-production activity from methanol aqueous solution, even without the aid of noble metal. When the ratio of RGO is 0.25 wt%, the highest H2-production rate was achieved. It increased by 10 fold than bare TiO2, reaching 149 μmol h-1 g-1 with quantum efficiency (QE) of 0.75%. The reasons were as follows. Firstly, the RGO nanosheets acted as electron acceptors. Secondly, some shallow trap states at the surface or interface of TiO2 were created by the reduction of GO during calcination. Thirdly, the redox potential position of graphene/graphene- was suitable. Fourthly, RGO could efficiently promote the separation of photogenerated electron-hole pairs and significantly enhance the photocatalytic H2-production activity. This interpretation was corroborated by transient photocurrent response. The aforementioned marvelous results provided a probable solution to replace noble metals (such as Pt) by graphene as an effective cocatalyst.

Effects of the interfacial charge injection properties of silver nanowire transparent conductive electrodes on the performance of organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Kim, Jin-Hoon; Triambulo, Ross E.; Park, Jin-Woo

2017-03-01

We investigated the charge injection properties of silver nanowire networks (AgNWs) in a composite-like structure with poly(2,3-dihydrothieno-1,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS). The composite films acted as the anodes and hole transport layers (HTLs) in organic light-emitting diodes (OLEDs). The current density (J)-voltage (V)-luminance (L) characteristics and power efficiency (ɛ) of the OLEDs were measured to determine their electrical and optical properties. The charge injection properties of the AgNWs in the OLEDs during operation were characterized via impedance spectroscopy (IS) by determining the variations in the capacitances (C) of the devices with respect to the applied V and the corresponding frequency (f). All measured results were compared with results for OLEDs fabricated on indium tin oxide (ITO) anodes. The OLEDs on AgNWs showed lower L and ɛ values than the OLEDs on ITO. It was also observed that AgNWs exhibit excellent charge injection properties and that the interfaces between the AgNWs and the HTL have very small charge injection barriers, resulting in an absence of charge carrier traps when charges move across these interfaces. However, in the AgNW-based OLED, there was a large mismatch in the number of injected holes and electrons. Furthermore, the highly conductive electrical paths of the AgNWs in the composite-like AgNW and PEDOT:PSS structure allowed a large leakage current of holes that did not participate in radiative recombination with the electrons; consequently, a lower ɛ was observed for the AgNW-based OLEDs than for the ITO-based OLEDs. To match the injection of electrons by the electron transport layer (ETL) in the AgNW-based OLED with that of holes by the AgNW/PEDOT:PSS composite anode, the electron injection barrier of the ETL was decreased by using the low work function polyethylenimine ethoxylated (PEIE) doped with n-type cesium carbonate (Cs2CO3). With the doped-PEIE, the performance of the AgNW-based OLED was

Electrochemical investigations of Co3Fe-RGO as a bifunctional catalyst for oxygen reduction and evolution reactions in alkaline media

NASA Astrophysics Data System (ADS)

Kumar, Surender; Kumar, Divyaratan; Kishore, Brij; Ranganatha, Sudhakar; Munichandraiah, Nookala; Venkataramanan, Natarajan S.

2017-10-01

Nanoparticles of Co3Fe alloy is prepared on reduced graphene oxide (RGO) sheets by modified polyol method. Synthesized alloy particles are characterized by various physicochemical techniques. TEM and SEM pictures showed homogeneously dispersed alloy nanoparticles on the RGO sheets. Electrochemistry of alloy nanoparticles is investigated in alkaline medium. The result shows that oxygen evaluation reaction (OER) activity of Co3Fe-RGO is higher than Pt-black particles. RDE studies in alkaline medium shows that oxygen reduction reaction (ORR) follow four electron pathway. It is suggest that Co3Fe-RGO is an efficient non-precious catalyst for oxygen (ORR/OER) reactions in alkaline electrolyte for PEMFC applications.

Enhanced Electrochemical Performances of Bi2O3/rGO Nanocomposite via Chemical Bonding as Anode Materials for Lithium Ion Batteries.

PubMed

Deng, Zhuo; Liu, Tingting; Chen, Tao; Jiang, Jiaxiang; Yang, Wanli; Guo, Jun; Zhao, Jianqing; Wang, Haibo; Gao, Lijun

2017-04-12

Bismuth oxide/reduced graphene oxide (termed Bi 2 O 3 @rGO) nanocomposite has been facilely prepared by a solvothermal method via introducing chemical bonding that has been demonstrated by Raman and X-ray photoelectron spectroscopy spectra. Tremendous single-crystal Bi 2 O 3 nanoparticles with an average size of ∼5 nm are anchored and uniformly dispersed on rGO sheets. Such a nanostructure results in enhanced electrochemical reversibility and cycling stability of Bi 2 O 3 @rGO composite materials as anodes for lithium ion batteries in comparison with agglomerated bare Bi 2 O 3 nanoparticles. The Bi 2 O 3 @rGO anode material can deliver a high initial capacity of ∼900 mAh/g at 0.1C and shows excellent rate capability of ∼270 mAh/g at 10C rates (1C = 600 mA/g). After 100 electrochemical cycles at 1C, the Bi 2 O 3 @rGO anode material retains a capacity of 347.3 mAh/g with corresponding capacity retention of 79%, which is significantly better than that of bare Bi 2 O 3 material. The lithium ion diffusion coefficient during lithiation-delithiation of Bi 2 O 3 @rGO nanocomposite has been evaluated to be around ∼10 -15 -10 -16 cm 2 /S. This work demonstrates the effects of chemical bonding between Bi 2 O 3 nanoparticles and rGO substrate on enhanced electrochemical performances of Bi 2 O 3 @rGO nanocomposite, which can be used as a promising anode alterative for superior lithium ion batteries.

Hierarchically structured graphene-carbon nanotube-cobalt hybrid electrocatalyst for seawater battery

NASA Astrophysics Data System (ADS)

Suh, Dong Hoon; Park, Sul Ki; Nakhanivej, Puritut; Kim, Youngsik; Hwang, Soo Min; Park, Ho Seok

2017-12-01

The design of cost-effective and highly active catalysts is a critical challenge. Inspired by the strong points of stability and conductivity of carbon nanotubes (CNTs), high catalytic activity of Co nanoparticles, and rapid ion diffusion and large accessible area of three-dimensional (3D) graphene, we demonstrate a novel strategy to construct a hierarchical hybrid structure consisting of Co/CoOx nanoparticles-incorporated CNT branches onto the 3D reduced graphene oxide (rGO) architecture. The surface-modified 3D rGO by steam activation process has a large surface area and abundant defect sites, which serve as active sites to uniformly grow Co/CoOx nanoparticles. Furthermore, the CNTs preserve their performance stably by encapsulating Co nanoparticles, while the uniformly decorated Co/CoOx nanoparticles exhibit superior electrocatalytic activity toward oxygen evolution/reduction reaction due to highly exposed active sites. Employing the hybrid particle electrocatalyst, the seawater battery operates stably at 0.01 mA cm-2 during 50 cycles, owing to the good electrocatalytic ability.

Nano-Sized Structurally Disordered Metal Oxide Composite Aerogels as High-Power Anodes in Hybrid Supercapacitors.

PubMed

Huang, Haijian; Wang, Xing; Tervoort, Elena; Zeng, Guobo; Liu, Tian; Chen, Xi; Sologubenko, Alla; Niederberger, Markus

2018-03-27

A general method for preparing nano-sized metal oxide nanoparticles with highly disordered crystal structure and their processing into stable aqueous dispersions is presented. With these nanoparticles as building blocks, a series of nanoparticles@reduced graphene oxide (rGO) composite aerogels are fabricated and directly used as high-power anodes for lithium-ion hybrid supercapacitors (Li-HSCs). To clarify the effect of the degree of disorder, control samples of crystalline nanoparticles with similar particle size are prepared. The results indicate that the structurally disordered samples show a significantly enhanced electrochemical performance compared to the crystalline counterparts. In particular, structurally disordered Ni x Fe y O z @rGO delivers a capacity of 388 mAh g -1 at 5 A g -1 , which is 6 times that of the crystalline sample. Disordered Ni x Fe y O z @rGO is taken as an example to study the reasons for the enhanced performance. Compared with the crystalline sample, density functional theory calculations reveal a smaller volume expansion during Li + insertion for the structurally disordered Ni x Fe y O z nanoparticles, and they are found to exhibit larger pseudocapacitive effects. Combined with an activated carbon (AC) cathode, full-cell tests of the lithium-ion hybrid supercapacitors are performed, demonstrating that the structurally disordered metal oxide nanoparticles@rGO||AC hybrid systems deliver high energy and power densities within the voltage range of 1.0-4.0 V. These results indicate that structurally disordered nanomaterials might be interesting candidates for exploring high-power anodes for Li-HSCs.

Evolution of Reduced Graphene Oxide-SnS2 Hybrid Nanoparticle Electrodes in Li-Ion Batteries.

PubMed

Modarres, Mohammad H; Lim, Jonathan Hua-Wei; George, Chandramohan; De Volder, Michael

2017-06-22

Hybrid nanomaterials where active battery nanoparticles are synthesized directly onto conductive additives such as graphene hold the promise of improving the cyclability and energy density of conversion and alloying type Li-ion battery electrodes. Here we investigate the evolution of hybrid reduced graphene oxide-tin sulfide (rGO-SnS 2 ) electrodes during battery cycling. These hybrid nanoparticles are synthesized by a one-step solvothermal microwave reaction which allows for simultaneous synthesis of the SnS 2 nanocrystals and reduction of GO. Despite the hybrid architecture of these electrodes, electrochemical impedance spectroscopy shows that the impedance doubles in about 25 cycles and subsequently gradually increases, which may be caused by an irreversible surface passivation of rGO by sulfur enriched conversion products. This surface passivation is further confirmed by post-mortem Raman spectroscopy of the electrodes, which no longer detects rGO peaks after 100 cycles. Moreover, galvanostatic intermittent titration analysis during the 1st and 100th cycles shows a drop in Li-ion diffusion coefficient of over an order of magnitude. Despite reports of excellent cycling performance of hybrid nanomaterials, our work indicates that in certain electrode systems, it is still critical to further address passivation and charge transport issues between the active phase and the conductive additive in order to retain high energy density and cycling performance.

Evolution of Reduced Graphene Oxide–SnS2 Hybrid Nanoparticle Electrodes in Li-Ion Batteries

PubMed Central

2017-01-01

Hybrid nanomaterials where active battery nanoparticles are synthesized directly onto conductive additives such as graphene hold the promise of improving the cyclability and energy density of conversion and alloying type Li-ion battery electrodes. Here we investigate the evolution of hybrid reduced graphene oxide–tin sulfide (rGO-SnS2) electrodes during battery cycling. These hybrid nanoparticles are synthesized by a one-step solvothermal microwave reaction which allows for simultaneous synthesis of the SnS2 nanocrystals and reduction of GO. Despite the hybrid architecture of these electrodes, electrochemical impedance spectroscopy shows that the impedance doubles in about 25 cycles and subsequently gradually increases, which may be caused by an irreversible surface passivation of rGO by sulfur enriched conversion products. This surface passivation is further confirmed by post-mortem Raman spectroscopy of the electrodes, which no longer detects rGO peaks after 100 cycles. Moreover, galvanostatic intermittent titration analysis during the 1st and 100th cycles shows a drop in Li-ion diffusion coefficient of over an order of magnitude. Despite reports of excellent cycling performance of hybrid nanomaterials, our work indicates that in certain electrode systems, it is still critical to further address passivation and charge transport issues between the active phase and the conductive additive in order to retain high energy density and cycling performance. PMID:28804530

Fern-like rGO/BiVO4 Hybrid Nanostructures for High-Energy Symmetric Supercapacitor.

PubMed

Patil, Santosh S; Dubal, Deepak P; Deonikar, Virendrakumar G; Tamboli, Mohaseen S; Ambekar, Jalindar D; Gomez-Romero, Pedro; Kolekar, Sanjay S; Kale, Bharat B; Patil, Deepak R

2016-11-23

Herein, we demonstrate the synthesis of rGO/BiVO 4 hybrid nanostructures by facile hydrothermal method. Morphological studies reveal that rGO sheets are embedded in the special dendritic fern-like structures of BiVO 4 . The rGO/BiVO 4 hybrid architecture shows the way to a rational design of supercapacitor, since these structures enable easy access of electrolyte ions by reducing internal resistance. Considering the unique morphological features of rGO/BiVO 4 hybrid nanostructures, their supercapacitive properties were investigated. The rGO/BiVO 4 electrode exhibits a specific capacitance of 151 F/g at the current density of 0.15 mA/cm 2 . Furthermore, we have constructed rGO/BiVO 4 symmetric cell which exhibits outstanding volumetric energy density of 1.6 mW h/cm 3 (33.7 W h/kg) and ensures rapid energy delivery with power density of 391 mW/cm 3 (8.0 kW/kg). The superior properties of symmetric supercapacitor can be attributed to the special dendritic fern-like BiVO 4 morphology and intriguing physicochemical properties of rGO.

Re-investigation on reduced graphene oxide/Ag2CO3 composite photocatalyst: An insight into the double-edged sword role of RGO

NASA Astrophysics Data System (ADS)

Wang, Wenguang; Liu, Yuan; Zhang, Haiyan; Qian, Yannan; Guo, Zuchen

2017-02-01

Coupling graphene or reduced graphene oxide (RGO) with semiconductor photocatalysts has previously been proven to be an effective way for enhancing the photocatalytic activity and stability of the photocatalysts. Herein, the Ag2CO3/reduced graphene oxide composite was successfully prepared by a facile chemical precipitation method. The physical and chemical properties of the photocatalysts were characterized by X-ray diffraction, Raman spectra, scanning electron microscope, X-ray photoelectron spectroscopy, UV-vis diffuse-reflection spectra. The photocatalytic activity and cycling stability of the photocatalysts were evaluated by photocatalytic degradation of rhodamine B under visible light irradiation. The results showed that the RGO indeed improves the photocatalytic activity of Ag2CO3/RGO, which can be attributed to the reduced charge recombination and enhanced dye adsorption as well as the light harvesting by RGO. Nevertheless, it played a negative role to the photocatalytic cycling stability due to the strong aggregation of Ag2CO3 particles brought by the RGO sheets. This work may provide a re-examination of the role of RGO in enhancing the photocatalytic performances of the photocatalysts.

Highly Active PdNi/RGO/Polyoxometalate Nanocomposite Electrocatalyst for Alcohol Oxidation.

PubMed

Hu, Jing; Wu, Xiaofeng; Zhang, Qingfan; Gao, Mingyan; Qiu, Haifang; Huang, Keke; Feng, Shouhua; Wang, Tingting; Yang, Ying; Liu, Zhelin; Zhao, Bo

2018-02-27

A PdNi/RGO/polyoxometalate nanocomposite has been successfully synthesized by a simple wet-chemical method. Characterizations such as transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy are employed to verify the morphology, structure, and elemental composition of the as-prepared nanocomposite. Inspired by the fast-developing fuel cells, the electrochemical catalytic performance of the nanocomposite toward methanol and ethanol oxidation in alkaline media is further tested. Notably, the nanocomposite exhibits excellent catalytic activity and long-term stability toward alcohol electrooxidation compared with the PdNi/RGO and commercial Pd/C catalyst. Furthermore, the electrochemical results reveal that the prepared nanocomposite is attractive as a promising electrocatalyst for direct alcohol fuel cells, in which the phosphotungstic acid plays a crucial role in enhancing the electrocatalytic activities of the catalyst.

Controlled Electromagnetically Induced Transparency and Fano Resonances in Hybrid BEC-Optomechanics

PubMed Central

Yasir, Kashif Ammar; Liu, Wu-Ming

2016-01-01

Cavity-optomechanics, a tool to manipulate mechanical effects of light to couple optical field with other physical objects, is the subject of increasing investigations, especially with regards to electromagnetically induced transparency (EIT). EIT, a result of Fano interference among different atomic transition levels, has acquired a significant importance in many areas of physics, such as atomic physics and quantum optics. However, controllability of such multi-dimensional systems has remained a crucial issue. In this report, we investigate the controllability of EIT and Fano resonances in hybrid optomechanical system composed of cigar-shaped Bose-Einstein condensate (BEC), trapped inside high-finesse Fabry-Pérot cavity with one vibrational mirror, driven by a single mode optical field and a transverse pump field. The transverse field is used to control the phenomenon of EIT. It is detected that the strength of transverse field is not only efficiently amplifying or attenuating out-going optical mode but also providing an opportunity to enhance the strength of Fano-interactions which leads to the amplification of EIT-window. To observe these phenomena in laboratory, we suggest a certain set of experimental parameters. The results provide a route for tunable manipulation of optical phenomena, like EIT, which could be a significant step in quantum engineering. PMID:26955789

Oxygen Vacancies in Shape Controlled Cu2O/Reduced Graphene Oxide/In2O3 Hybrid for Promoted Photocatalytic Water Oxidation and Degradation of Environmental Pollutants.

PubMed

Liu, Jie; Ke, Jun; Li, Degang; Sun, Hongqi; Liang, Ping; Duan, Xiaoguang; Tian, Wenjie; Tadé, Moses O; Liu, Shaomin; Wang, Shaobin

2017-04-05

A novel shape controlled Cu 2 O/reduced graphene oxide/In 2 O 3 (Cu 2 O/RGO/In 2 O 3 ) hybrid with abundant oxygen vacancies was prepared by a facile, surfactant-free method. The hybrid photocatalyst exhibits an increased photocatalytic activity in water oxidation and degradation of environmental pollutants (methylene blue and Cr 6+ solutions) compared with pure In 2 O 3 and Cu 2 O materials. The presence of oxygen vacancies in Cu 2 O/RGO/In 2 O 3 and the formation of heterojunction between In 2 O 3 and Cu 2 O induce extra diffusive electronic states above the valence band (VB) edge and reduce the band gap of the hybrid consequently. Besides, the increased activity of Cu 2 O/RGO/In 2 O 3 hybrid is also attributed to the alignment of band edge, a process that is assisted by different Fermi levels between In 2 O 3 and Cu 2 O, as well as the charge transfer and distribution onto the graphene sheets, which causes the downshift of VB of In 2 O 3 and the significant increase in its oxidation potential. Additionally, a built-in electric field is generated on the interface of n-type In 2 O 3 and p-type Cu 2 O, suppressing the recombination of photoinduced electron-hole pairs and allowing the photogenerated electrons and holes to participate in the reduction and oxidation reactions for oxidizing water molecules and pollutants more efficiently.

Porous V2O5/RGO/CNT hierarchical architecture as a cathode material: Emphasis on the contribution of surface lithium storage

PubMed Central

Palanisamy, Kowsalya; Um, Ji Hyun; Jeong, Mihee; Yoon, Won-Sub

2016-01-01

A three dimensional vanadium pentoxide/reduced graphene oxide/carbon nanotube (3D V2O5/RGO/CNT) composite is synthesized by microwave-assisted hydrothermal method. The combination of 2D RGO and 1D CNT establishes continuous 3D conductive network, and most notably, the 1D CNT is designed to form hierarchically porous structure by penetrating into V2O5 microsphere assembly constituted of numerous V2O5 nanoparticles. The highly porous V2O5 microsphere enhances electrolyte contact and shortens Li+ diffusion path as a consequence of its developed surface area and mesoporosity. The successive phase transformations of 3D V2O5/RGO/CNT from α-phase to ε-, δ-, γ-, and ω-phase and its structural reversibility upon Li+ intercalation/de-intercalation are investigated by in situ XRD analysis, and the electronic and local structure reversibility around vanadium atom in 3D V2O5/RGO/CNT is observed by in situ XANES analysis. The 3D V2O5/RGO/CNT achieves a high capacity of 220 mAh g−1 at 1 C after 80 cycles and an excellent rate capability of 100 mAh g−1 even at a considerably high rate of 20 C. The porous 3D V2O5/RGO/CNT structure not only provides facile Li+ diffusion into bulk but contributes to surface Li+ storage as well, which enables the design of 3D V2O5/RGO/CNT composite to become a promising cathode architecture for high performance LIBs. PMID:27511434

Covalently coupled hybrid of graphitic carbon nitride with reduced graphene oxide as a superior performance lithium-ion battery anode

NASA Astrophysics Data System (ADS)

Fu, Yongsheng; Zhu, Junwu; Hu, Chong; Wu, Xiaodong; Wang, Xin

2014-10-01

An in situ chemical synthetic approach has been designed for the fabrication of a covalently coupled hybrid consisting of graphitic carbon nitride (g-C3N4) with reduced graphene oxide (rGO) with differing g-C3N4/rGO ratio. The epoxy groups of graphene oxide (GO) undergo a nucleophilic substitution reaction with dicyandiamide (C2H4N4) to form the C2H4N4-GO composite via a covalent C-N bond, and then both the in situ polymerization of C2H4N4 and the thermal reduction of GO can be achieved at higher temperatures, forming the covalently coupled g-C3N4-rGO. FT-IR, CP-MAS NMR and XPS analyses, clearly revealed a covalent interaction between the g-C3N4 and rGO sheets. The g-C3N4-rGO exhibits an unprecedented high, stable and reversible capacity of 1525 mA h g-1 at a current density of 100 mA g-1 after 50 cycles. Even at a large current density of 1000 mA g-1, a reversible capacity of 943 mA h g-1 can still be retained. The superior electrochemical performance of g-C3N4-rGO is attributed to the specific characteristics of the unique nanostructure of g-C3N4-rGO and the concerted effects of g-C3N4 and rGO, including covalent interactions between the two moieties, the good conductivity and high special surface area of the nanocomposite, as well as the template effect of the planar amino group of g-C3N4 for the dispersed decoration of Li+ ions.An in situ chemical synthetic approach has been designed for the fabrication of a covalently coupled hybrid consisting of graphitic carbon nitride (g-C3N4) with reduced graphene oxide (rGO) with differing g-C3N4/rGO ratio. The epoxy groups of graphene oxide (GO) undergo a nucleophilic substitution reaction with dicyandiamide (C2H4N4) to form the C2H4N4-GO composite via a covalent C-N bond, and then both the in situ polymerization of C2H4N4 and the thermal reduction of GO can be achieved at higher temperatures, forming the covalently coupled g-C3N4-rGO. FT-IR, CP-MAS NMR and XPS analyses, clearly revealed a covalent interaction between

A new protocol for the distribution of MnO2 nanoparticles on rGO sheets and the resulting electrochemical performance

NASA Astrophysics Data System (ADS)

Samdani, Jitendra; Samdani, Kunda; Kim, Nam Hoon; Lee, Joong Hee

2017-03-01

Herein, reduced graphene oxide (rGO)/MnO2 hybrid materials were prepared via a direct redox reaction between MnCl2 and KMnO4 on reduced graphene oxide (rGO). A systematic study was carried out to understand the role of KMnO4. The morphology and microstructure of the as-prepared composite was characterized using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman Spectroscopy. Results indicate that the concentrations of KMnO4 have a detrimental effect on the distribution of MnO2 nanoparticles on rGO sheets and hence on electrochemical properties. The electrochemical capacitive behavior of the as-prepared composite was investigated using cyclic voltammetry (CV), galvanostatic charge discharge, and electrochemical impedance spectroscopy (EIS) in 1 M Na2SO4 aqueous electrolyte solution. At the optimum concentration of KMnO4, the as-prepared rGM-1 composite shows a high specific capacitance of 366 F/g at a scan rate of 10 mV/s. The composite also exhibits good electrocatalytic activity towards the oxidation of dopamine (DA), exhibiting a low detection limit of 2.3 × 10-7 M with a wide linear range between 2.5 × 10-7 M and 2.30 × 10-4 M. Hence, the use of rGO/MnO2 at an optimized concentration of KMnO4 is a potential competitive candidate in supercapacitor and biosensor applications.

Encapsulating Bi2Ti2O7 (BTO) with reduced graphene oxide (RGO): an effective strategy to enhance photocatalytic and photoelectrocatalytic activity of BTO.

PubMed

Gupta, Satyajit; Subramanian, Vaidyanathan Ravi

2014-11-12

Multimetal oxides (AxByOz) offer a higher degree of freedom compared to single metal oxides (AOx) in that these oxides facilitate (i) designing nanomaterials with greater stability, (ii) tuning of the optical bandgap, and (iii) promoting visible light absorption. However, all AxByOz materials such as pyrochlores (A2B2O7)--referred to here as band-gap engineered composite oxide nanomaterials or BECONs--are traditionally prone to severe charge recombination at their surface. To alleviate the charge recombination, an effective strategy is to employ reduced graphene oxide (RGO) as a charge separator. The BECON and the RGO with oppositely charged functional groups attached to them can be integrated at the interface by employing a simple electrostatic self-assembly approach. As a case study, the approach is demonstrated using the Pt-free pyrochlore bismuth titanate (BTO) with RGO, and the application of the composite is investigated for the first time. When tested as a photocatalyst toward hydrogen production, an increase of ∼ 250% using BTO in the presence of RGO was observed. Further, photoelectrochemical measurements indicate an enhancement of ∼ 130% in the photocurrent with RGO inclusion. These two results firmly establish the viability of the electrostatic approach and the inclusion of RGO. The merits of the RGO addition is identified as (i) the RGO-assisted improvement in the separation of the photogenerated charges of BTO, (ii) the enhanced utilization of the charges in a photocatalytic process, and (iii) the maintenance of the BTO/RGO structural integrity after repeated use (established through reusability analysis). The success of the self-assembly strategy presented here lays the foundation for developing other forms of BECONs, belonging to perovskites (ABO3), sillenite (A12BO20), or delafossite (ABO2) groups, hitherto written off due to limited or no photoelectrochemicalactivity.

High-Performance Flexible Asymmetric Supercapacitor Based on CoAl-LDH and rGO Electrodes

NASA Astrophysics Data System (ADS)

Li, Shuoshuo; Cheng, Pengpeng; Luo, Jiaxian; Zhou, Dan; Xu, Weiming; Li, Jingwei; Li, Ruchun; Yuan, Dingsheng

2017-07-01

A flexible asymmetric supercapacitor (ASC) based on a CoAl-layered double hydroxide (CoAl-LDH) electrode and a reduced graphene oxide (rGO) electrode was successfully fabricated. The CoAl-LDH electrode as a positive electrode was synthesized by directly growing CoAl-LDH nanosheet arrays on a carbon cloth (CC) through a facile hydrothermal method, and it delivered a specific capacitance of 616.9 F g-1 at a current density of 1 A g-1. The rGO electrode as a negative electrode was synthesized by coating rGO on the CC via a simple dip-coating method and revealed a specific capacitance of 110.0 F g-1 at a current density of 2 A g-1. Ultimately, the advanced ASC offered a broad voltage window (1.7 V) and exhibited a high superficial capacitance of 1.77 F cm-2 at 2 mA cm-2 and a high energy density of 0.71 mWh cm-2 at a power density of 17.05 mW cm-2, along with an excellent cycle stability (92.9% capacitance retention over 8000 charge-discharge cycles).

Tribological behaviour predictions of r-GO reinforced Mg composite using ANN coupled Taguchi approach

NASA Astrophysics Data System (ADS)

Kavimani, V.; Prakash, K. Soorya

2017-11-01

This paper deals with the fabrication of reduced graphene oxide (r-GO) reinforced Magnesium Metal Matrix Composite (MMC) through a novel solvent based powder metallurgy route. Investigations over basic and functional properties of developed MMC reveals that addition of r-GO improvises the microhardness upto 64 HV but however decrement in specific wear rate is also notified. Visualization of worn out surfaces through SEM images clearly explains for the occurrence of plastic deformation and the presence of wear debris because of ploughing out action. Taguchi coupled Artificial Neural Network (ANN) technique is adopted to arrive at optimal values of the input parameters such as load, reinforcement weight percentage, sliding distance and sliding velocity and thereby achieve minimal target output value viz. specific wear rate. Influence of any of the input parameter over specific wear rate studied through ANOVA reveals that load acting on pin has a major influence with 38.85% followed by r-GO wt. % of 25.82%. ANN model developed to predict specific wear rate value based on the variation of input parameter facilitates better predictability with R-value of 98.4% when compared with the outcomes of regression model.

Hierarchical architecture of ReS2/rGO composites with enhanced electrochemical properties for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Qi, Fei; Chen, Yuanfu; Zheng, Binjie; He, Jiarui; Li, Qian; Wang, Xinqiang; Lin, Jie; Zhou, Jinhao; Yu, Bo; Li, Pingjian; Zhang, Wanli

2017-08-01

Rhenium disulfide (ReS2), a two-dimensional (2D) semiconductor, has attracted more and more attention due to its unique anisotropic electronic, optical, mechanical properties. However, the facile synthesis and electrochemical property of ReS2 and its composite are still necessary to be researched. In this study, for the first time, the ReS2/reduced graphene oxide (rGO) composites have been synthesized through a facile and one-pot hydrothermal method. The ReS2/rGO composites exhibit a hierarchical, interconnected, and porous architecture constructed by nanosheets. As anode for lithium-ion batteries, the as-synthesized ReS2/rGO composites deliver a large initial capacity of 918 mAh g-1 at 0.2 C. In addition, the ReS2/rGO composites exhibit much better electrochemical cycling stability and rate capability than that of bare ReS2. The significant enhancement in electrochemical property can be attributed to its unique architecture constructed by nanosheets and porous structure, which can allow for easy electrolyte infiltration, efficient electron transfer, and ionic diffusion. Furthermore, the graphene with high electronic conductivity can provide good conductive passageways. The facile synthesis approach can be extended to prepare other 2D transition metal dichalcogenides semiconductors for energy storage and catalytic application.

Rapid determination of cadmium in rice using an all-solid RGO-enhanced light addressable potentiometric sensor.

PubMed

Zhang, Wen; Xu, Yiwei; Zou, Xiaobo

2018-09-30

Herein, an all-solid light addressable potentiometric sensor (LAPS) is presented for determination of cadmium (Cd) in rice. On the working surface of the LAPS, reduced graphene oxide (RGO) is introduced as a part of ion-to-electron transducer to improve ionophore behaviors. The composite modification of RGO and ionophore is validated with scanning electron microscopy. The as-fabricated sensor presents a rapid response in less than 10 s to target Cd. Meanwhile, it shows lower noise (0.23 mV) and better limit of detection (0.002 mg L -1 ) than LAPS (control) without RGO modification (0.37 mV; 0.008 mg L -1 ). With the proposed method, satisfactory precision, accuracy and selectivity are also established. This method is adopted in an extensive survey for 25 rice samples from 5 regions in China. The results are in very good agreement with those obtained using inductively-coupled plasma-mass spectrometry. Copyright © 2018 Elsevier Ltd. All rights reserved.

Morphology-controlled synthesis of self-assembled LiFePO4/C/RGO for high-performance Li-ion batteries.

PubMed

Lin, Mei; Chen, Yuming; Chen, Bolei; Wu, Xiao; Kam, Kifung; Lu, Wei; Chan, Helen Lai Wa; Yuan, Jikang

2014-10-22

Novel architectured LiFePO4 (LFP) that consisted of ordered LFP nanocubes was prepared through a facile hydrothermal method using polyethylene glycol (PEG) as a surfactant. The micro/nanostructured LFP with various morphologies ranging from cube cluster to rugby-like structure was synthesized via controlling the pH values of the precursor. A reasonable assembly process elucidating the formation of the hierarchical structure is also provided based on the experimental results. After a combination of carbon (C) coating and reduced graphene oxide (RGO) wrapping, the obtained LFP/C/RGO composites exhibit enhanced electrochemical performance compared to that of blank LFP synthesized under the same condition. Among as-synthesized cube-cluster-like, dumbbell-like, rod-like, and rugby-like composites, the rugby-like LFP/C/RGO reveal the best electrochemical properties with the discharge specific capacity of ∼150 mA h g(-1) after 100 cycles and a high reversible specific capacity of 152 mA h g(-1) at 0.1 C. The prepared LFP/C/RGO composite can be a promising cathode material for high energy, low cost, and environmentally friendly lithium-ion batteries.

Optimization of NiFe2O4/rGO composite electrode for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Chen; Wang, Xia; Li, Shandong; Li, Qiang; Xu, Jie; Liu, Xiaomin; Liu, Changkun; Xu, Yuanhong; Liu, Jingquan; Li, Hongliang; Guo, Peizhi; Zhao, Xiu Song

2017-09-01

The combination of carbon compositing and the proper choice of binders in one system offer an effective strategy for improving electrode performance for lithium ion batteries (LIBs). Here, we focus on the optimization of reduced graphene oxide content in NiFe2O4/reduced graphene oxide (abbreviated to NiFe2O4/rGO) composites and the proper choice of binders to enhance the cycling stability of the NiFe2O4 electrode. The NiFe2O4/rGO composites were fabricated by a hydrothermal-annealing method, in which the mean size of spinel NiFe2O4 nanoparticles was approximately 20 nm. When tested as anode materials for LIBs, the NiFe2O4/rGO electrodes with carboxymethylcellulose (CMC) binder exhibited excellent lithium-storage performance including high reversible capacity, good cycling durability and high-rate capability. The capacity could be retained as high as 1105 mAh g-1 at a current density of 100 mA g-1 for over 50 cycles, even cycled at higher current density of 1000 mA g-1, a capacity of 800 mAh g-1can be obtained, whereas the electrode with the polyvinylidene fluoride (PVDF) binder suffered from rapid capacity decay under the same test conditions. As a result, the NiFe2O4/rGO composites with CMC binder electrode in this work are promising as anodes for high-performance LIBs, resulting from the synergistic effect of optimal graphene content and proper choice of binder.

Simple and label-free electrochemical impedance Amelogenin gene hybridization biosensing based on reduced graphene oxide.

PubMed

Benvidi, Ali; Rajabzadeh, Nooshin; Mazloum-Ardakani, Mohammad; Heidari, Mohammad Mehdi; Mulchandani, Ashok

2014-08-15

The increasing desire for sensitive, easy, low-cost, and label free methods for the detection of DNA sequences has become a vital matter in biomedical research. For the first time a novel label-free biosensor for sensitive detection of Amelogenin gene (AMEL) using reduced graphene oxide modified glassy carbon electrode (GCE/RGO) has been developed. In this work, detection of DNA hybridization of the target and probe DNA was investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The optimum conditions were found for the immobilization of probe on RGO surface and its hybridization with the target DNA. CV and EIS carried out in an aqueous solution containing [Fe(CN)6](3-/4-) redox pair have been used for the biosensor characterization. The biosensor has a wide linear range from 1.0×10(-20) to 1.0×10(-14)M with the lower detection limit of 3.2×10(-21)M. Moreover, the present electrochemical detection offers some unique advantages such as ultrahigh sensitivity, simplicity, and feasibility for apparatus miniaturization in analytical tests. The excellent performance of the biosensor is attributed to large surface-to-volume ratio and high conductivity of RGO, which enhances the probe absorption and promotes direct electron transfer between probe and the electrode surface. This electrochemical DNA sensor could be used for the detection of specific ssDNA sequence in real biological samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Cross-linked g-C3 N4 /rGO nanocomposites with tunable band structure and enhanced visible light photocatalytic activity.

PubMed

Li, Yibing; Zhang, Haimin; Liu, Porun; Wang, Dan; Li, Ying; Zhao, Huijun

2013-10-11

Cross-linked rather than non-covalently bonded graphitic carbon nitride (g-C3 N4 )/reduced graphene oxide (rGO) nanocomposites with tunable band structures have been successfully fabricated by thermal treatment of a mixture of cyanamide and graphene oxide with different weight ratios. The experimental results indicate that compared to pure g-C3 N4 , the fabricated CN/rGO nanocomposites show narrowed bandgaps with an increased in the rGO ratio. Furthermore, the band structure of the CN/rGO nanocomposites can be readily tuned by simply controlling the weight ratio of the rGO. It is found that an appropriate rGO ratio in nanocomposite leads to a noticeable positively shifted valence band edge potential, meaning an increased oxidation power. The tunable band structure of the CN/rGO nanocomposites can be ascribed to the formation of C-O-C covalent bonding between the rGO and g-C3 N4 layers, which is experimentally confirmed by Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) data. The resulting nanocomposites are evaluated as photocatalysts by photocatalytic degradation of rhodamine B (RhB) and 4-nitrophenol under visible light irradiation (λ > 400 nm). The results demonstrate that the photocatalytic activities of the CN/rGO nanocomposites are strongly influenced by rGO ratio. With a rGO ratio of 2.5%, the CN/rGO-2.5% nanocomposite exhibits the highest photocatalytic efficiency, which is almost 3.0 and 2.7 times that of pure g-C3 N4 toward photocatalytic degradation of RhB and 4-nitrophenol, respectively. This improved photocatalytic activity could be attributed to the improved visible light utilization, oxidation power, and electron transport property, due to the significantly narrowed bandgap, positively shifted valence band-edge potential, and enhanced electronic conductivity. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced photovoltaic performance of inverted hybrid bulk-heterojunction solar cells using TiO2/reduced graphene oxide films as electron transport layers

NASA Astrophysics Data System (ADS)

Morais, Andreia; Alves, João Paulo C.; Lima, Francisco Anderson S.; Lira-Cantu, Monica; Nogueira, Ana Flavia

2015-01-01

In this study, we investigated inverted hybrid bulk-heterojunction solar cells with the following configuration: fluorine-doped tin oxide (FTO) |TiO2/RGO|P3HT:PC61BM|V2O5 or PEDOT:PSS|Ag. The TiO2/GO dispersions were prepared by sol-gel method, employing titanium isopropoxide and graphene oxide (GO) as starting materials. The GO concentration was varied from 0.1 to 4.0 wt%. The corresponding dispersions were spin-coated onto FTO substrates and a thermal treatment was performed to remove organic materials and to reduce GO to reduced graphene oxide (RGO). The TiO2/RGO films were characterized by x-ray diffraction, Raman spectroscopy, and microscopy techniques. Atomic force microscopy (AFM) images showed that the addition of RGO significantly changes the morphology of the TiO2 films, with loss of uniformity and increase in surface roughness. Independent of the use of V2O5 or PEDOT: PSS films as the hole transport layer, the incorporation of 2.0 wt% of RGO into TiO2 films was the optimal concentration for the best organic photovoltaic performance. The solar cells based on TiO2/RGO (2.0 wt%) electrode exhibited a ˜22.3% and ˜28.9% short circuit current density (Jsc) and a power conversion efficiency enhancement, respectively, if compared with the devices based on pure TiO2 films. Kelvin probe force microscopy images suggest that the incorporation of RGO into TiO2 films can promote the appearance of regions with different charge dissipation capacities.

Co-Percolating Graphene-Wrapped Silver Nanowire Network for High Performance, Highly Stable, Transparent Conducting Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Ruiyi; Das, Suprem R; Jeong, Changwook

Transparent conducting electrodes (TCEs) require high transparency and low sheet resistance for applications in photovoltaics, photodetectors, flat panel displays, touch screen devices, and imagers. Indium tin oxide (ITO), or other transparent conductive oxides, have been used, and provide a baseline sheet resistance (RS) vs. transparency (T) relationship. Several alternative material systems have been investigated. The development of high-performance hybrid structures provides a route towards robust, scalable and low-cost approaches for realizing high-performance TCE.

Cellulose nanofibril/reduced graphene oxide/carbon nanotube hybrid aerogels for highly flexible and all-solid-state supercapacitors

Treesearch

Qifeng Zheng; Zhiyong Cai; Zhenqiang Ma; Shaoqin Gong

2015-01-01

A novel type of highly flexible and all-solid-state supercapacitor that uses cellulose nanofibril (CNF)/reduced graphene oxide (RGO)/carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4 poly (vinyl alcohol) PVA gel as the electrolyte was developed and is reported here. These flexible solid-state supercapacitors...

Reduced graphene oxide supported MnS nanotubes hybrid as a novel non-precious metal electrocatalyst for oxygen reduction reaction with high performance

NASA Astrophysics Data System (ADS)

Tang, Yongfu; Chen, Teng; Guo, Wenfeng; Chen, Shunji; Li, Yanshuai; Song, Jianzheng; Chang, Limin; Mu, Shichun; Zhao, Yufeng; Gao, Faming

2017-09-01

Electronic structure of Mn cations, electric conductivity of active materials and three dimensional structure for mass transport play vital roles in the electrocatalytic activity of Mn-based electrocatalysts for oxygen reduction reaction (ORR). To construct efficient and robust Mn-based electrocatalysts, MnS nanotubes anchored on reduced graphene oxide (MnS-NT@rGO) hybrid was synthesized and used as a novel non-precious metal electrocatalyst for ORR. The formation of nano-tubular structure, which offers more active sites and suitable channels for mass transport to enhance the electrocatalytic activity towards ORR, are carefully illustrated based on the core-dissolution/shell-recrystallization type Ostwald ripening effect. Tuned electronic structure of Mn cations, enhanced electric conductivity and suitable nano-tubular structure endow MnS-NT@rGO electrocatalyst comparative catalytic activity to commercial 20 wt % Pt/C in alkaline electrolyte. The MnS-NT@rGO electrocatalyst exhibits higher catalytic activity than rGO supported MnS nanoparticles (MnS-NP@rGO) and MnS nanotubes without rGO substrate (MnS-NT), as well as rGO supported Mn(OH)2 (Mn(OH)2@rGO) and rGO supported MnO (MnO@rGO). Moreover, the MnS-NT@rGO electrocatalyst shows superior durability and methanol tolerance to commercial Pt/C.

Synthesis of reduced Graphene Oxide (rGO) using different treatments of Graphene Oxide (GO)

NASA Astrophysics Data System (ADS)

Zainuddin, M. F.; Nik Raikhan, N. H.; Othman, N. H.; Abdullah, W. F. H.

2018-05-01

In this work, a combined chemical and mechanical method was used for the production of graphene instead of chemical method only. The use of mechanical sonication was to assists exfoliation graphene oxide (GO) besides the used of chemical reagents. Then, the reduction of GO into graphene was carried out using L-ascorbic acid. The effects sonication cause synthesis of GO undergoes peeling graphitic layer and at the same time expose the layer with oxidizing agent. The properties of GO and reduced-graphene oxide (rGO) using various routes were investigated using XRD and FTIR. The main characteristics peak was observed at 7°and 9° for GO prepared using sonication and without sonication, respectively. The decreased of 2-theta degree of GO prepared using sonication indicates that the d-value becomes bigger. Estimation of average diameter rGO (with sonication) was 24.49 nm while rGO (without sonication) was 126.2 nm. The reduction of both GO was then carried out using an environmentally reducing agent, ascorbic acid. It was found that the L-ascorbic acid was effective in removing oxygenated functional groups. The conductivity values obtained for rGO-s was 7640 S/m while rGO-ws was is 678 S/m.

Structural and Morphological Investigation for Water-Processed Graphene Oxide/Single-Walled Carbon Nanotubes Hybrids

NASA Astrophysics Data System (ADS)

Muda, M. R.; Ramli, M. M.; Mat Isa, S. S.; Halin, D. S. C.; Talip, L. F. A.; Mazelan, N. S.; Anhar, N. A. M.; Danial, N. A.

2017-06-01

New group of materials derived from hybridization of single walled carbon nanotubes (SWCNTs) and graphene oxide (GO) which resulting novel three dimensional (3D) materials generates an outstanding properties compared to corresponding SWCNTs and GO/Graphene. In this paper, we describe a simple approach using water processing method to develop integrated rGO/GO-SWCNT hybrids with different hybrid ratios. The hybrid ratios were varied into three divided ratio and the results were compared between pristine SWCNTs and GO in order to investigate the structural density and morphology of these carbonaceous materials. With an optimized ratio of rGO/GO-SWCNT, the hybrid shows a well-organized hybrid film structures with less defects density sites. The optimized mixture ratio emphasized the important of both rGO and SWCNTs in the hybrid structures. Morphological structural and defects density degrees were examined by Field Emission Scanning Electron Microscopy (FESEM) and Raman spectroscopy.

A novel strategy to prepare Ge@C/rGO hybrids as high-rate anode materials for lithium ion batteries

NASA Astrophysics Data System (ADS)

Wang, Bangrun; Wen, Zhaoyin; Jin, Jun; Hong, Xiaoheng; Zhang, Sanpei; Rui, Kun

2017-02-01

Germanium is considered as a promising anode material for lithium ion batteries (LIBs) due to its high-capacity. However, owing to the huge volume variation during cycling, the batteries based on germanium anodes usually show poor cyclability and inferior rate capability. Herein, we demonstrated a novel strategy to uniformly anchor the core-shell structured germanium@carbon (Ge@C) on the reduced graphene oxide (rGO) nanosheets by the strong adhesion of dopamine. In the resulting Ge@C/rGO hybrid, the amorphous carbon layer and rGO nanosheets can effectively reduce the agglomeration of germanium and provide buffer matrix for the volume change in electrochemical lithium reactions. When used as anode materials for LIBs, Ge@C/rGO hybrids deliver a reversible capacity of 1074.4 mA h g-1 at 2C after 600 cycles (with capacity retention of 96.5%) and high rate capability of 436 mA h g-1 at 20C after 200 cycles. The encouraging electrochemical performance clearly demonstrates that Ge@C/rGO hybrids could be a potential anode material with high capacity, excellent rate capability, and good cycling stability for LIBs.

Nano ZnO enhanced 3D porous reduced graphene oxide (RGO) for light-weight superior electromagnetic interference shielding

NASA Astrophysics Data System (ADS)

Dai, Xiaoqing

2017-02-01

Nano ZnO enhanced 3D porous reduced graphene oxide (RGO) with superior electromagnetic interferece (EMI) shielding efficiency (SE) was fabricated through a UV enhanced hydrothermal process. In this study, a composite with 10 wt% of 3D-RGO/ZnO was tested in a broadband frequency range from 2 to 18 GHz. Under the whole test conditions, the ratio of SEA/SET is higher than 50% and the maximum value can reach to 94%, indicating the shielding mechanism mainly attributes to absorption. The EMI SE showed that the thinnest thicknesses to shield different frequency range are 0.7 mm for 10 dB, 1.6 mm for 20 dB and 3.7 mm for 30 dB, which suggests 3D-RGO/ZnO could meet the requirement of new generate EMI shielding material.

Reverse osmosis desalination of chitosan cross-linked graphene oxide/titania hybrid lamellar membranes.

PubMed

Deng, Hui; Sun, Penzhan; Zhang, Yingjiu; Zhu, Hongwei

2016-07-08

With excellent mass transport properties, graphene oxide (GO)-based lamellar membranes are believed to have great potential in water desalination. In order to quantify whether GO-based membranes are indeed suitable for reverse osmosis (RO) desalination, three sub-micrometer thick GO-based lamellar membranes: GO-only, reduced GO (RGO)/titania (TO) nanosheets and RGO/TO/chitosan (CTS) are prepared, and their RO desalination performances are evaluated in a home-made RO test apparatus. The photoreduction of GO by TO improves the salt rejection, which increases slowly with the membrane thickness. The RGO/TO/CTS hybrid membranes exhibit higher rejection rates of only about 30% (greater than threefold improvement compared with a GO-only membrane) which is still inferior compared to other commercial RO membranes. The low rejection rates mainly arise from the pressure-induced weakening of the ion-GO interlayer interactions. Despite the advantages of simple, low-cost preparation, high permeability and selectivity of GO-based lamellar membranes, as the current desalination performances are not high enough to afford practical application, there still remains a great challenge to realize high performance separation membranes for water desalination applications.

Highly transparent, low-haze, hybrid cellulose nanopaper as electrodes for flexible electronics

Treesearch

Xuezhu Xu; Jian Zhou; Long Jiang; Gilles Lubineau; Tienkhee Ng; Boon S. Ooi; Hsien-Yu Liao; Chao Shen; Long Chen; Junyong Zhu

2016-01-01

Paper is an excellent candidate to replace plastics as a substrate for flexible electronics due to its low cost, renewability and flexibility. Cellulose nanopaper (CNP), a new type of paper made of nanosized cellulose fibers, is a promising substrate material for transparent and flexible electrodes due to its potentially high transparency and high mechanical strength....

Degradation of sulfamethazine using Fe3O4-Mn3O4/reduced graphene oxide hybrid as Fenton-like catalyst.

PubMed

Wan, Zhong; Wang, Jianlong

2017-02-15

In this paper, Fe 3 O 4 -Mn 3 O 4 /reduced graphene oxide (RGO) hybrid was synthesized through polyol process and impregnation method and used as heterogeneous Fenton-like catalyst for degradation of sulfamethazine (SMT) in aqueous solution. The hybrid catalyst had higher catalytic efficiency compared with Fe 3 O 4 -Mn 3 O 4 and Mn 3 O 4 as catalyst for degradation of SMT . The effects of pH value, H 2 O 2 concentration, catalyst dosage, initial SMT concentration and temperature on SMT degradation were investigated. The removal efficiency of SMT was about 98% at following optimal conditions: pH=3, T=35°C, Fe 3 O 4 /Mn 3 O 4 -RGO composites=0.5g/L, H 2 O 2 =6mM. The inhibitor experiments indicated that the main active species was hydroxyl radicals (·OH) on catalyst surface. At last, the possible catalytic mechanism was proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

Durability Improvement of Pt/RGO Catalysts for PEMFC by Low-Temperature Self-Catalyzed Reduction.

PubMed

Sun, Kang Gyu; Chung, Jin Suk; Hur, Seung Hyun

2015-12-01

Pt/C catalyst used for polymer electrolyte membrane fuel cells (PEMFCs) displays excellent initial performance, but it does not last long because of the lack of durability. In this study, a Pt/reduced graphene oxide (RGO) catalyst was synthesized by the polyol method using ethylene glycol (EG) as the reducing agent, and then low-temperature hydrogen bubbling (LTHB) treatment was introduced to enhance the durability of the Pt/RGO catalyst. The cyclic voltammetry (CV), oxygen reduction reaction (ORR) analysis, and transmittance electron microscopy (TEM) results suggested that the loss of the oxygen functional groups, because of the hydrogen spillover and self-catalyzed dehydration reaction during LTHB, reduced the carbon corrosion and Pt agglomeration and thus enhanced the durability of the electrocatalyst.

SnO2 quantum dots decorated on RGO: a superior sensitive, selective and reproducible performance for a H2 and LPG sensor

NASA Astrophysics Data System (ADS)

Mishra, R. K.; Upadhyay, S. B.; Kushwaha, Ajay; Kim, Tae-Hyung; Murali, G.; Verma, Ranjana; Srivastava, Manish; Singh, Jay; Sahay, P. P.; Hee Lee, Seung

2015-07-01

We report the H2 and LPG gas sensing behavior of RGO/SnO2 QDs synthesized by a surfactant assisted hydrothermal method. The RGO/SnO2 QD based sensor shows a high response of ~89.3% to H2 and ~92.4% to LPG for 500 ppm test gas concentration at operating temperatures of 200 °C and 250 °C, respectively. Further, the RGO/SnO2 QD based sensor shows good selectivity for H2 and LPG in the presence of other interfering gases such as ammonia, chloroform, toluene, benzene, acetone, n-butylacetate, acetic acid and formic acid. We observed that the gas response to H2 is 29.8 times higher than that to acetic acid whereas the gas response to LPG is 17.8 times higher than that to formic acid. Long-term analyses have also been performed to demonstrate the reproducible nature of the RGO/SnO2 QD based sensor over passing time which shows excellent reproducibility.We report the H2 and LPG gas sensing behavior of RGO/SnO2 QDs synthesized by a surfactant assisted hydrothermal method. The RGO/SnO2 QD based sensor shows a high response of ~89.3% to H2 and ~92.4% to LPG for 500 ppm test gas concentration at operating temperatures of 200 °C and 250 °C, respectively. Further, the RGO/SnO2 QD based sensor shows good selectivity for H2 and LPG in the presence of other interfering gases such as ammonia, chloroform, toluene, benzene, acetone, n-butylacetate, acetic acid and formic acid. We observed that the gas response to H2 is 29.8 times higher than that to acetic acid whereas the gas response to LPG is 17.8 times higher than that to formic acid. Long-term analyses have also been performed to demonstrate the reproducible nature of the RGO/SnO2 QD based sensor over passing time which shows excellent reproducibility. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02837j

Cu2ZnSnS4/MoS2-Reduced Graphene Oxide Heterostructure: Nanoscale Interfacial Contact and Enhanced Photocatalytic Hydrogen Generation.

PubMed

Ha, Enna; Liu, Wei; Wang, Luyang; Man, Ho-Wing; Hu, Liangsheng; Tsang, Shik Chi Edman; Chan, Chris Tsz-Leung; Kwok, Wai-Ming; Lee, Lawrence Yoon Suk; Wong, Kwok-Yin

2017-01-03

Hydrogen generation from water using noble metal-free photocatalysts presents a promising platform for renewable and sustainable energy. Copper-based chalcogenides of earth-abundant elements, especially Cu 2 ZnSnS 4 (CZTS), have recently arisen as a low-cost and environment-friendly material for photovoltaics and photocatalysis. Herein, we report a new heterostructure consisting of CZTS nanoparticles anchored onto a MoS 2 -reduced graphene oxide (rGO) hybrid. Using a facile two-step method, CZTS nanoparticles were in situ grown on the surface of MoS 2 -rGO hybrid, which generated high density of nanoscale interfacial contact between CZTS and MoS 2 -rGO hybrid. The photoexcited electrons of CZTS can be readily transported to MoS 2 through rGO backbone, reducing the electron-hole pair recombination. In photocatalytic hydrogen generation under visible light irradiation, the presence of MoS 2 -rGO hybrids enhanced the hydrogen production rate of CZTS by 320%, which can be attributed to the synergetic effect of increased charge separation by rGO and more catalytically active sites from MoS 2 . Furthermore, this CZTS/MoS 2 -rGO heterostructure showed much higher photocatalytic activity than both Au and Pt nanoparticle-decorated CZTS (Au/CZTS and Pt/CZTS) photocatalysts, indicating the MoS 2 -rGO hybrid is a better co-catalyst for photocatalytic hydrogen generation than the precious metal. The CZTS/MoS 2 -rGO system also demonstrated stable photocatalytic activity for a continuous 20 h reaction.

Cu2ZnSnS4/MoS2-Reduced Graphene Oxide Heterostructure: Nanoscale Interfacial Contact and Enhanced Photocatalytic Hydrogen Generation

NASA Astrophysics Data System (ADS)

Ha, Enna; Liu, Wei; Wang, Luyang; Man, Ho-Wing; Hu, Liangsheng; Tsang, Shik Chi Edman; Chan, Chris Tsz-Leung; Kwok, Wai-Ming; Lee, Lawrence Yoon Suk; Wong, Kwok-Yin

2017-01-01

Hydrogen generation from water using noble metal-free photocatalysts presents a promising platform for renewable and sustainable energy. Copper-based chalcogenides of earth-abundant elements, especially Cu2ZnSnS4 (CZTS), have recently arisen as a low-cost and environment-friendly material for photovoltaics and photocatalysis. Herein, we report a new heterostructure consisting of CZTS nanoparticles anchored onto a MoS2-reduced graphene oxide (rGO) hybrid. Using a facile two-step method, CZTS nanoparticles were in situ grown on the surface of MoS2-rGO hybrid, which generated high density of nanoscale interfacial contact between CZTS and MoS2-rGO hybrid. The photoexcited electrons of CZTS can be readily transported to MoS2 through rGO backbone, reducing the electron-hole pair recombination. In photocatalytic hydrogen generation under visible light irradiation, the presence of MoS2-rGO hybrids enhanced the hydrogen production rate of CZTS by 320%, which can be attributed to the synergetic effect of increased charge separation by rGO and more catalytically active sites from MoS2. Furthermore, this CZTS/MoS2-rGO heterostructure showed much higher photocatalytic activity than both Au and Pt nanoparticle-decorated CZTS (Au/CZTS and Pt/CZTS) photocatalysts, indicating the MoS2-rGO hybrid is a better co-catalyst for photocatalytic hydrogen generation than the precious metal. The CZTS/MoS2-rGO system also demonstrated stable photocatalytic activity for a continuous 20 h reaction.

Cu2ZnSnS4/MoS2-Reduced Graphene Oxide Heterostructure: Nanoscale Interfacial Contact and Enhanced Photocatalytic Hydrogen Generation

PubMed Central

Ha, Enna; Liu, Wei; Wang, Luyang; Man, Ho-Wing; Hu, Liangsheng; Tsang, Shik Chi Edman; Chan, Chris Tsz-Leung; Kwok, Wai-Ming; Lee, Lawrence Yoon Suk; Wong, Kwok-Yin

2017-01-01

Hydrogen generation from water using noble metal-free photocatalysts presents a promising platform for renewable and sustainable energy. Copper-based chalcogenides of earth-abundant elements, especially Cu2ZnSnS4 (CZTS), have recently arisen as a low-cost and environment-friendly material for photovoltaics and photocatalysis. Herein, we report a new heterostructure consisting of CZTS nanoparticles anchored onto a MoS2-reduced graphene oxide (rGO) hybrid. Using a facile two-step method, CZTS nanoparticles were in situ grown on the surface of MoS2-rGO hybrid, which generated high density of nanoscale interfacial contact between CZTS and MoS2-rGO hybrid. The photoexcited electrons of CZTS can be readily transported to MoS2 through rGO backbone, reducing the electron-hole pair recombination. In photocatalytic hydrogen generation under visible light irradiation, the presence of MoS2-rGO hybrids enhanced the hydrogen production rate of CZTS by 320%, which can be attributed to the synergetic effect of increased charge separation by rGO and more catalytically active sites from MoS2. Furthermore, this CZTS/MoS2-rGO heterostructure showed much higher photocatalytic activity than both Au and Pt nanoparticle-decorated CZTS (Au/CZTS and Pt/CZTS) photocatalysts, indicating the MoS2-rGO hybrid is a better co-catalyst for photocatalytic hydrogen generation than the precious metal. The CZTS/MoS2-rGO system also demonstrated stable photocatalytic activity for a continuous 20 h reaction. PMID:28045066

Highly Oriented Graphene Sponge Electrode for Ultra High Energy Density Lithium Ion Hybrid Capacitors.

PubMed

Ahn, Wook; Lee, Dong Un; Li, Ge; Feng, Kun; Wang, Xiaolei; Yu, Aiping; Lui, Gregory; Chen, Zhongwei

2016-09-28

Highly oriented rGO sponge (HOG) can be easily synthesized as an effective anode for application in high-capacity lithium ion hybrid capacitors. X-ray diffraction and morphological analyses show that successfully exfoliated rGO sponge on average consists of 4.2 graphene sheets, maintaining its three-dimensional structure with highly oriented morphology even after the thermal reduction procedure. Lithium-ion hybrid capacitors (LIC) are fabricated in this study based on a unique cell configuration which completely eliminates the predoping process of lithium ions. The full-cell LIC consisting of AC/HOG-Li configuration has resulted in remarkably high energy densities of 231.7 and 131.9 Wh kg(-1) obtained at 57 W kg(-1) and 2.8 kW kg(-1). This excellent performance is attributed to the lithium ion diffusivity related to the intercalation reaction of AC/HOG-Li which is 3.6 times higher that of AC/CG-Li. This unique cell design and configuration of LIC presented in this study using HOG as an effective anode is an unprecedented example of performance enhancement and improved energy density of LIC through successful increase in cell operation voltage window.

SnO2 quantum dots decorated on RGO: a superior sensitive, selective and reproducible performance for a H2 and LPG sensor.

PubMed

Mishra, R K; Upadhyay, S B; Kushwaha, Ajay; Kim, Tae-Hyung; Murali, G; Verma, Ranjana; Srivastava, Manish; Singh, Jay; Sahay, P P; Lee, Seung Hee

2015-07-28

We report the H2 and LPG gas sensing behavior of RGO/SnO2 QDs synthesized by a surfactant assisted hydrothermal method. The RGO/SnO2 QD based sensor shows a high response of ∼89.3% to H2 and ∼92.4% to LPG for 500 ppm test gas concentration at operating temperatures of 200 °C and 250 °C, respectively. Further, the RGO/SnO2 QD based sensor shows good selectivity for H2 and LPG in the presence of other interfering gases such as ammonia, chloroform, toluene, benzene, acetone, n-butylacetate, acetic acid and formic acid. We observed that the gas response to H2 is 29.8 times higher than that to acetic acid whereas the gas response to LPG is 17.8 times higher than that to formic acid. Long-term analyses have also been performed to demonstrate the reproducible nature of the RGO/SnO2 QD based sensor over passing time which shows excellent reproducibility.

Emerging Robust Heterostructure of MoS2-rGO for High-Performance Supercapacitors.

PubMed

Saraf, Mohit; Natarajan, Kaushik; Mobin, Shaikh M

2018-05-16

The intermittent nature of renewable energy resources has led to a continuous mismatch between energy demand and supply. A possible solution to overcome this persistent problem is to design appropriate energy-storage materials. Supercapacitors based on different nanoelectrode materials have emerged as one of the promising storage devices. In this work, we investigate the supercapacitor properties of a molybdenum disulfide-reduced graphene oxide (rGO) heterostructure-based binder-free electrode, which delivered a high specific capacitance (387.6 F g -1 at 1.2 A g -1 ) and impressive cycling stability (virtually no loss up to 1000 cycles). In addition, the possible role of rGO in the composite toward synergistically enhanced supercapacitance has been highlighted. Moreover, an attempt has been made to correlate the electrochemical impedance spectroscopy studies with the voltammetric analyses. The performance exceeds that of the reported state-of-the-art structures.

Synthesis of biocompatible hydrophobic silica-gelatin nano-hybrid by sol-gel process.

PubMed

Smitha, S; Shajesh, P; Mukundan, P; Nair, T D R; Warrier, K G K

2007-03-15

Silica-biopolymer hybrid has been synthesised using colloidal silica as the precursor for silica and gelatin as the biopolymer counterpart. The surface modification of the hybrid material has been done with methyltrimethoxysilane leading to the formation of biocompatible hydrophobic silica-gelatin hybrid. Here we are reporting hydrophobic silica-gelatin hybrid and coating precursor for the first time. The hybrid gel has been evaluated for chemical modification, thermal degradation, hydrophobicity, particle size, transparency under the UV-visible region and morphology. FTIR spectroscopy has been used to verify the presence of CH(3) groups which introduce hydrophobicity to the SiO2-MTMS-gelatin hybrids. The hydrophobic property has also been tailored by varying the concentration of methyltrimethoxysilane. Contact angle by Wilhelmy plate method of transparent hydrophobic silica-gelatin coatings has been found to be as high as approximately 95 degrees . Oxidation of the organic group which induces the hydrophobic character occurs at 530 degrees C which indicates that the surface hydrophobicity is retained up to that temperature. Optical transmittance of SiO2-MTMS-gelatin hybrid coatings on glass substrates has been found to be close to 100% which will enable the hybrid for possible optical applications and also for preparation of transparent biocompatible hydrophobic coatings on biological substrates such as leather.

Electrical Mapping of Silver Nanowire Networks: A Versatile Tool for Imaging Network Homogeneity and Degradation Dynamics during Failure.

PubMed

Sannicolo, Thomas; Charvin, Nicolas; Flandin, Lionel; Kraus, Silas; Papanastasiou, Dorina T; Celle, Caroline; Simonato, Jean-Pierre; Muñoz-Rojas, David; Jiménez, Carmen; Bellet, Daniel

2018-05-22

Electrical stability and homogeneity of silver nanowire (AgNW) networks are critical assets for increasing their robustness and reliability when integrated as transparent electrodes in devices. Our ability to distinguish defects, inhomogeneities, or inactive areas at the scale of the entire network is therefore a critical issue. We propose one-probe electrical mapping (1P-mapping) as a specific simple tool to study the electrical distribution in these discrete structures. 1P-mapping has allowed us to show that the tortuosity of the voltage equipotential lines of AgNW networks under bias decreases with increasing network density, leading to a better electrical homogeneity. The impact of the network fabrication technique on the electrical homogeneity of the resulting electrode has also been investigated. Then, by combining 1P-mapping with electrical resistance measurements and IR thermography, we propose a comprehensive analysis of the evolution of the electrical distribution in AgNW networks when subjected to increasing voltage stresses. We show that AgNW networks experience three distinctive stages: optimization, degradation, and breakdown. We also demonstrate that the failure dynamics of AgNW networks at high voltages occurs through a highly correlated and spatially localized mechanism. In particular the in situ formation of cracks could be clearly visualized. It consists of two steps: creation of a crack followed by propagation nearly parallel to the equipotential lines. Finally, we show that current can dynamically redistribute during failure, by following partially damaged secondary pathways through the crack.

Active control and switching of broadband electromagnetically induced transparency in symmetric metadevices

NASA Astrophysics Data System (ADS)

Yahiaoui, Riad; Manjappa, Manukumara; Srivastava, Yogesh Kumar; Singh, Ranjan

2017-07-01

Electromagnetically induced transparency (EIT) arises from coupling between the bright and dark mode resonances that typically involve subwavelength structures with broken symmetry, which results in an extremely sharp transparency band. Here, we demonstrate a tunable broadband EIT effect in a symmetry preserved metamaterial structure at the terahertz frequencies. Alongside, we also envisage a photo-active EIT effect in a hybrid metal-semiconductor metamaterial, where the transparency window can be dynamically switched by shining near-infrared light beam. A robust coupled oscillator model explains the coupling mechanism in the proposed design, which shows a good agreement with the observed results on tunable broadband transparency effect. Such active, switchable, and broadband metadevices could have applications in delay bandwidth management, terahertz filtering, and slow light effects.

Direct synthesis of Cu{sub 2}O-RGO nanocomposite on Cu foil by thermal evaporation method and its field emission study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bansode, Sanjeewani; Khare, Ruchita; Harpale, Kashmira

2015-06-24

In this work, a facile one step thermal evaporation method for deposition of Cu{sub 2}O nanoparticles on RGO sheets to form Cu{sub 2}O-RGO nanocomposite is discussed. To the best of our knowledge, this is the first report on Cu{sub 2}O-RGO nanocomposite, directly grown on Cu foil by a simple thermal evaporation route. The as –prepared nanocomposite exhibits well dispersed Cu{sub 2}O nanoparticles distributed all over the graphene sheet. Field emission properties of the nanocomposite were investigated at a base pressure of 1*10{sup −8} torr. The turn on field, required to draw emission current density of 0.1µA/cm2, was found to bemore » 3.8V/µm with a maximum emission current density of 80 µA/cm2 at an applied field of 6.8 V/µm. Moreover, the nanocomposite shows fairly good emission stability without significant degradation of emission current. The FE results seem to be encouraging, indicative of potential candidature of the Cu{sub 2}O-RGO nanocomposite emitter as an electron source for practical applications in vacuum nanoelectronic devices.« less

Electrochemical Sensing of Dopamine, Uric Acid and Ascorbic Acid Using tRGO-TiO2 Nanocomposites.

PubMed

Rajamani, A R; Kannan, Rajesh; Krishnan, Sruthy; Ramakrishnan, S; Raj, S Mohan; Kumaresan, D; Kothurkar, Nikhil; Rangarajan, Murali

2015-07-01

This work reports a graphene-based nonenzymatic electrochemical sensing platform for the detection of dopamine (DA), uric acid (UA), and ascorbic acid (AA). Graphene oxide, synthesized by modified Hummers method, was thermally reduced in an induction furnace at 200 °C in an Ar-H2 atmosphere to obtain thermally reduced graphene oxide (tRGO). Nanocomposites of tRGO-TiO2 were obtained by a hydrothermal method, and were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). FTIR spectra showed Ti-O-C peaks, indicating covalent linkage between the TiO2 nanoparticles and the reduced graphene oxide sheets. Glassy carbon electrode (GCE) was modified with the nanocomposite (tRGO-TiO2-GCE), and the modified electrode could detect dopamine (DA: 1 to 1000 µM), uric acid (UA: 1 to 900 µM), and ascorbic acid (AA: 10 to 1000 µM) in each other's presence over wide ranges, with adequate separation in peak potentials. Differential pulse voltammetry experiments yielded linear responses with sensitivities of 133.18, 33.96, and 155.59 µA mM(-1) cm(-2) for DA, UA, and AA, respectively.

Decomposition of acetaminophen in water by a gas phase dielectric barrier discharge plasma combined with TiO2-rGO nanocomposite: Mechanism and degradation pathway.

PubMed

Zhang, Guyu; Sun, Yabing; Zhang, Chunxiao; Yu, Zhongqing

2017-02-05

Acetaminophen (APAP) served as the model pollutant to evaluate the feasibility of pollutant removal by gas phase dielectric barrier discharge plasma combined with the titanium dioxide-reduced Graphene Oxide (TiO 2 -rGO) nanocomposite. TiO 2 -rGO nanocomposite was prepared using the modified hydrothermal method and characterized by TEM and XPS before and after plasma process. The results indicated that the APAP degradation efficiency was significantly improved to 92% after 18min of discharge plasma treatment coupling 0.25gL -1 TiO 2 -rGO 5%wt at 18kV, compared with the plasma alone and plasma combined with P25 TiO 2 . The degradation mechanism for APAP in this system was studied by investigating the effects of the operational variables (e.g. discharge voltage and pH value) and the amount of the generated active species; and the results showed that O 3 and H 2 O 2 yields were influenced notably by adding TiO 2 -rGO. Also, it was observed that, compared with unused TiO 2 -rGO, the photocatalytic performance of used TiO 2 -rGO declined after several recirculation times due to the further reduction of Graphene Oxide in plasma system. Finally, intermediate products were analyzed by UV-vis spectrometry and HPLC/MS, and possible transformation pathways were identified with the support of theoretically calculating the frontier electron density of APAP. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis of the RGO/Al2O3 core-shell nanocomposite flakes and characterization of their unique electrostatic properties using zeta potential measurements

NASA Astrophysics Data System (ADS)

Jastrzębska, A. M.; Karcz, J.; Letmanowski, R.; Zabost, D.; Ciecierska, E.; Zdunek, J.; Karwowska, E.; Siekierski, M.; Olszyna, A.; Kunicki, A.

2016-01-01

The aim of this study was to describe the influence of the modification of electrostatic properties of RGO/Al2O3 core-shell nanocomposite flakes. The amount of crystalline form of aluminum oxide was very small. It existed mostly in amorphous phase in the form of covalently bonded to GO surface. The morphological, structural and physicochemical investigations results showed that spherical Al2O3 nanoparticles (ca. 41 nm) in gamma phase completely covered the surface of curly-shaped RGO flakes and acted as a spreader between individual flakes. The high BET specific surface area of the analyzed composite (119.71 m2/g) together with very low open porosity (0.479 cm3/g) indicated that RGO/Al2O3 nanocomposite flakes showed low tendency to agglomeration. The zeta potential curves obtained for RGO/Al2O3 core-shell nanocomposite flakes were differing from curves obtained for GO and Al2O3 suspensions in distilled water and neutral environment. The specific electrostatic properties of the core-shell system of RGO/Al2O3 flakes had an influence on its surface charge (zeta potential) which was measured by applying an external electric field. The FTIR and Raman investigations results also confirmed that the Cdbnd O species were not taking part in the surface amphoteric reactions resulting in the formation of electrostatic surface charge.

Preparation of highly conductive, transparent, and flexible graphene/silver nanowires substrates using non-thermal laser photoreduction

NASA Astrophysics Data System (ADS)

Anis, Badawi; Mostafa, A. M.; El Sayed, Z. A.; Khalil, A. S. G.; Abouelsayed, A.

2018-07-01

We present the preparation of highly conducting, transparent, and flexible reduced graphene oxide/silver nanowires (rGO/SNWs) substrates using non-thermal laser photoreduction method. High quality monolayers graphene oxide (GO) solution has been prepared by the chemical oxidation of thermally expanded large area natural graphite. Silver nanowires was prepared by using the typical polyol method. Uniform hybrid GO/silver nanowires (GO/SNWs) was prepared by growing the nanowires from silver nuclei in the presence of GO. Uniform and high-quality rGO/SNWs thin films were prepared using a dip-coating technique and were reduced to highly electrically conductive graphene and transparent conductive films using non-thermal laser scribe method. The laser scribed rGO/SNWs hybrid film exhibited 80% transparency with 70 Ω □-1 after 20 min of dipping in GO/SNWs solution.

Additive Manufacturing of Transparent Silica Glass from Solutions.

PubMed

Cooperstein, Ido; Shukrun, Efrat; Press, Ofir; Kamyshny, Alexander; Magdassi, Shlomo

2018-06-06

A sol, aqueous solution-based ink is presented for fabrication of 3D transparent silica glass objects with complex geometries, by a simple 3D printing process conducted at room temperature. The ink combines a hybrid ceramic precursor that can undergo both the photopolymerization reaction and a sol-gel process, both in the solution form, without any particles. The printing is conducted by localized photopolymerization with the use of a low-cost 3D printer. Following printing, upon aging and densifying, the resulting objects convert from a gel to a xerogel and then to a fused silica. The printed objects, which are composed of fused silica, are transparent and have tunable density and refractive indices.

The preparation of TiO2@rGO nanocomposite efficiently activated with UVA/LED and H2O2 for high rate oxidation of acetaminophen: Catalyst characterization and acetaminophen degradation and mineralization

NASA Astrophysics Data System (ADS)

Cheshme Khavar, Amir Hossein; Moussavi, Gholamreza; Mahjoub, Ali Reza

2018-05-01

The present work was focused on the preparation of TiO2@rGO nanocomposite using an innovative facile synthesis method and the investigation of its photocatalytic activity in a UVA/LED photoreactor. The XRD patterns indicated anatase structure for all samples. Presence of rGO in nanocomposites was confirmed by FT-IR and Raman spectra. Also, mono-dispersed TiO2 nanoparticles on rGO sheet were shown in the SEM and HRTEM images. The prepared TiO2@rGO nanocomposite was used as the photocatalyst for degradation of acetaminophen (ACT) in the photoreactor illuminated with UVA/LEDs having the intensity of 95 μW/cm2. The complete degradation of 50 mg/L ACT was attained within 50 min in the LED/TiO2@rGO process while P25/LED process only showed 17% ACT degradation under similar experimental conditions. The photocatalytic activity was strongly affected by the rGO to TiO2 ratio in the nanocomposites and the highest photocatalytic activity was observed at 3.0 wt.% of rGO. Reaction with free radOH was the main mechanism involved in the ACT photodegradation in the TiO2@rGO/LED process under the selected conditions. The performance of LED/TiO2@rGO process improved by four and three times in ACT degradation and mineralization, respectively, at the presence of H2O2. As made TiO2@rGO nanocompsite could preserve its catalytic activity during five consecutive recycles in the process. Accordingly, TiO2@rGO nanocomposite is an active and stable catalyst in the UVA/LED photoreactor for high rate degradation of pharmaceuticals in the contaminated water.

High performance Li2MnO3/rGO composite cathode for lithium ion batteries

NASA Astrophysics Data System (ADS)

Zhao, Wei; Xiong, Lilong; Xu, Youlong; Li, Houli; Ren, Zaihuang

2017-05-01

The novel composite Li2MnO3 (LMO)/reduced graphene oxide (rGO) has been synthesized successfully. Based on the scanning electron microscopy and transmission electron microscopy, LMO is found to distribute separately on the rGO sheets by forming a laminated structure, which is in favor of good electrical contact between the cathode active materials and the rGO matrix, and also facilitates the separation of LMO secondary particles with reduced size. Cyclic voltammetry and electrochemical impedance spectroscopy tests show that the charge transfer resistance decreases from 81.2 Ω for LMO to 29.6 Ω for LMO/rGO composite. The Li-ion diffusion coefficient of LMO/rGO composite is almost triple that of LMO. As a result, the LMO/rGO composite delivers an initial discharge capacity of 284.9 mAh g-1 with a capacity retention of 86.6% after 45 cycles at 0.1 C between 2.0 and 4.6 V. Cycle performance is even better at a higher current density 0.2 C while the retention ratio is up to 97.1% after 45 cycles. The rate capability is also significantly enhanced, and the LMO/rGO composite could exhibit a large discharge capacity of 123.7 mAh g-1 which is more than three times larger than that of LMO (40.8 mAh g-1) at a high rate of 8 C.

P-type transparent conducting oxides.

PubMed

Zhang, Kelvin H L; Xi, Kai; Blamire, Mark G; Egdell, Russell G

2016-09-28

Transparent conducting oxides constitute a unique class of materials combining properties of electrical conductivity and optical transparency in a single material. They are needed for a wide range of applications including solar cells, flat panel displays, touch screens, light emitting diodes and transparent electronics. Most of the commercially available TCOs are n-type, such as Sn doped In2O3, Al doped ZnO, and F doped SnO2. However, the development of efficient p-type TCOs remains an outstanding challenge. This challenge is thought to be due to the localized nature of the O 2p derived valence band which leads to difficulty in introducing shallow acceptors and large hole effective masses. In 1997 Hosono and co-workers (1997 Nature 389 939) proposed the concept of 'chemical modulation of the valence band' to mitigate this problem using hybridization of O 2p orbitals with close-shell Cu 3d (10) orbitals. This work has sparked tremendous interest in designing p-TCO materials together with deep understanding the underlying materials physics. In this article, we will provide a comprehensive review on traditional and recently emergent p-TCOs, including Cu(+)-based delafossites, layered oxychalcogenides, nd (6) spinel oxides, Cr(3+)-based oxides (3d (3)) and post-transition metal oxides with lone pair state (ns (2)). We will focus our discussions on the basic materials physics of these materials in terms of electronic structures, doping and defect properties for p-type conductivity and optical properties. Device applications based on p-TCOs for transparent p-n junctions will also be briefly discussed.

Copercolating Networks: An Approach for Realizing High-Performance Transparent Conductors using Multicomponent Nanostructured Networks

NASA Astrophysics Data System (ADS)

Das, Suprem R.; Sadeque, Sajia; Jeong, Changwook; Chen, Ruiyi; Alam, Muhammad A.; Janes, David B.

2016-06-01

Although transparent conductive oxides such as indium tin oxide (ITO) are widely employed as transparent conducting electrodes (TCEs) for applications such as touch screens and displays, new nanostructured TCEs are of interest for future applications, including emerging transparent and flexible electronics. A number of twodimensional networks of nanostructured elements have been reported, including metallic nanowire networks consisting of silver nanowires, metallic carbon nanotubes (m-CNTs), copper nanowires or gold nanowires, and metallic mesh structures. In these single-component systems, it has generally been difficult to achieve sheet resistances that are comparable to ITO at a given broadband optical transparency. A relatively new third category of TCEs consisting of networks of 1D-1D and 1D-2D nanocomposites (such as silver nanowires and CNTs, silver nanowires and polycrystalline graphene, silver nanowires and reduced graphene oxide) have demonstrated TCE performance comparable to, or better than, ITO. In such hybrid networks, copercolation between the two components can lead to relatively low sheet resistances at nanowire densities corresponding to high optical transmittance. This review provides an overview of reported hybrid networks, including a comparison of the performance regimes achievable with those of ITO and single-component nanostructured networks. The performance is compared to that expected from bulk thin films and analyzed in terms of the copercolation model. In addition, performance characteristics relevant for flexible and transparent applications are discussed. The new TCEs are promising, but significant work must be done to ensure earth abundance, stability, and reliability so that they can eventually replace traditional ITO-based transparent conductors.

Bioinspired Multifunctional Paper-Based rGO Composites for Solar-Driven Clean Water Generation.

PubMed

Lou, Jinwei; Liu, Yang; Wang, Zhongyong; Zhao, Dengwu; Song, Chengyi; Wu, Jianbo; Dasgupta, Neil; Zhang, Wang; Zhang, Di; Tao, Peng; Shang, Wen; Deng, Tao

2016-06-15

Reusing polluted water through various decontamination techniques has appeared as one of the most practical approaches to address the global shortage of clean water. Rather than relying on single decontamination mechanism, herein we report the preparation and utilization of paper-based composites for multifunctional solar-driven clean water generation that is inspired by the multiple water purification approaches in biological systems. The reduced graphene oxide (rGO) sheets within such composites can efficiently remove organic contaminants through physical adsorption mechanism. Under solar irradiation, the floating rGO composites can instantly generate localized heating, which not only can directly generate clean water through distillation mechanism but also significantly enhance adsorption removal performance with the assistance of upward vapor flow. Such porous-structured paper-based composites allow for facile incorporation of photocatalysts to regenerate clean water out of contaminated water with combined adsorption, photodegradation, and interfacial heat-assisted distillation mechanisms. Within a homemade all-in-one water treatment device, the practical applicability of the composites for multifunctional clean water generation has been demonstrated.

Electrical characterization of reduced graphene oxide (rGO) on organic thin film transistor (OTFT)

NASA Astrophysics Data System (ADS)

Musa, Nurhazwani; Halim, Nurul Farhanah Ab.; Ahmad, Mohd Noor; Zakaria, Zulkhairi; Hashim, Uda

2017-03-01

A green method and eco-friendly solution were used to chemically reduce graphene oxide (GO) to graphene using green reductant. In this study, graphene oxide (GO) were prepared by using Tours method. Then, reduced graphene oxides (rGO) were prepared by using three typical reduction agents: L-ascorbic acid (L-AA), formamidinesulfinic acid (FAS) and sodium sulfite (Na2SO3). The reduced materials were characterized by Fourier transform infrared spectroscopy (FTIR), Thermo gravimetric analysis (TGA) and X-ray diffraction (XRD). Graphene based organic thin film transistor (G-OTFT) was prepared by a spin coating and thermal evaporation technique. The electrical characterization of G-OTFT was analyzed by using semiconductor parameter analyzer (SPA). The G-OTFT devices show p-type semiconducting behaviour. This article focuses on the synthesis and reduction of graphene oxide using three different reductants in order to maximise its electrical conductivity. The rGO product demonstrated a good electrical conductivity performance with highly sensitivity sensor.

Synthesis of LiFePO4/Li2SiO3/reduced Graphene Oxide (rGO) Composite via Hydrothermal Method

NASA Astrophysics Data System (ADS)

Arifin, M.; Iskandar, F.; Aimon, A. H.; Munir, M. M.; Nuryadin, B. W.

2016-08-01

LiFePO4 is a type of cathode active material used for lithium ion batteries. It has a high electrochemical performance. However, it suffers from certain disadvantages such as a very low intrinsic electronic conductivity and low ionic diffusion. This study was conducted to increase the conductivity of LiFePO4. We have investigated the addition of Li2SiO3 and reduced graphene oxide (rGO) to LiFePO4. The objective of this research was to synthesize LiFePO4/Li2SiO3/rGO via hydrothermal method. Fourier transform infrared spectroscopy (FTIR) measurement showed that the peaks corresponded to the vibration of LiFePO4/Li2SiO3. Further, X-ray diffraction (XRD) measurement confirmed a single phase of LiFePO4. Finally, scanning electron microscopy (SEM) images showed that rGO was distributed on the LiFePO4/Li2SiO3 structure.

Facial development of high performance room temperature NO2 gas sensors based on ZnO nanowalls decorated rGO nanosheets

NASA Astrophysics Data System (ADS)

Liu, Zongyuan; Yu, Lingmin; Guo, Fen; Liu, Sheng; Qi, Lijun; Shan, Minyu; Fan, Xinhui

2017-11-01

A highly sensitive NO2 gas sensor based on ZnO nanowalls decorated rGO nanosheets was fabricated using a thermal reduction and soft solution process. The highly developed interconnected microporous networks of ZnO nanowalls were anchored homogeneously on the surface of reduced graphene oxide (rGO). Sensors fabricated with heterojunction structures achieved a higher response (S = 9.61) and shorter response-recovery (25 s, 15 s) behavior at room temperature to 50 ppm level NO2 effectively in contrast to those sensors based on net ZnO nanowalls or rGO layers. The stability and selectivity of ZnO/rGO heterojunction were carried out. Meanwhile, the effects of humidity on ZnO/rGO heterojunction gas sensor were investigated. The more preferable sensing performance of ZnO/rGO heterojunction to NO2 was discussed. It can be surmised that this NO2 gas sensor has potential for use as a portable room temperature gas sensor.

One-pot hydrothermal synthesis of mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide hybrid material and its enhanced photocatalytic activity.

PubMed

Wang, Xinwei; Tian, Hongwei; Cui, Xiaoqiang; Zheng, Weitao; Liu, Yichun

2014-09-14

We successfully synthesized mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide (Z(x)CSG) hybrid materials as photocatalysts using a facile one-pot hydrothermal reaction, in which graphene oxide (GO) was easily reduced (RGO), and simultaneously Zn(x)Cd(1-x)S (Z(x)CS) nanoparticles (NPs) with a mesoporous structure were uniformly dispersed on the RGO sheets. By well tuning the band gap from 3.42 to 2.21 eV by changing the molar ratio of Zn/Cd (or Zn content), Z(x)CSG with an optimal zinc content has been found to have a significant absorption in the visible light (VL) region. In addition, under VL irradiation (λ > 420 nm), Z(x)CSG also showed zinc content-dependent photocatalytic efficiencies for the degradation of methylene blue (MB). Our findings are that, among Z(x)CSG, Z(0.4)CSG displayed not only a superior photodegradation efficiency of MB (98%), but also good removal efficiency of total organic carbon (TOC) (67%). Furthermore, Z(0.4)CSG had a high photocatalytic stability, and could be used repeatedly. The enhanced photocatalytic activity for Z(0.4)CSG could be attributed to a synergistic effect between mesoporous Z(x)CS NPs and RGO, including the optimal band gap and the moderate conduction band position for ZxCS (compared to CdS), efficient separation and transfer ability of photogenerated electron/hole pairs in the presence of RGO sheets, and relatively high surface area for both mesoporous Z(x)CS NPs and RGO.

High solar-light photocatalytic activity of using Cu3Se2/rGO nanocomposites synthesized by a green co-precipitation method

NASA Astrophysics Data System (ADS)

Nouri, Morteza; Saray, Abdolali Moghaddam; Azimi, H. R.; Yousefi, Ramin

2017-11-01

Current work presents a facile, cost-effective, and green method to synthesize copper selenide nanostructures and copper selenide/graphene nanocomposites. The products were synthesized by a co-precipitation method by glycine amino acid as a green surfactant and graphene oxide (GO) sheets as a graphene source. X-ray diffraction patterns (XRD) of the products indicated that the products were Cu2Se3 with tetragonal phase. Fourier transform infrared (FTIR) spectroscopy and the XRD patterns indicated that the GO sheets were changed into reduced GO (rGO) during the synthesis process. Scanning and transmission electron microscopy (SEM and TEM) images showed the nanoparticles (NPs) that were decorated on rGO sheets had the significantly smaller size in compared to the pristine NPs. UV-vis results revealed that, the absorption peak of the products were in the visible region with a band-gap value between 1.85 eV and 1.95 eV. Finally, the products were applied as photocatalytic materials to remove Methylene Blue (MB) dye under solar-light and visible-light irradiation conditions. It was observed; the rGO had a significant role in enhancing the photocatalytic performance of the products and Cu2Se3/rGO (15%) could degrade more than 91% and 73% of MB only during 1 h under solar-light and visible-light sources, respectively.

Novel stable hard transparent conductors in TiO2-TiC system: Design materials from scratch

PubMed Central

Meng, Xiangying; Liu, Dongyan; Dai, Xuefeng; Pan, Haijun; Wen, Xiaohong; Zuo, Liang; Qin, Gaowu

2014-01-01

Two new ternary compounds in the TiO2-TiC system, Ti5C2O6 and Ti3C2O2, are reported for the first time based on ab initio evolutionary algorithm. Ti5C2O6 has a tube-structure in which sp1 hybridized carbon chains run through the lattice along the b-axis; while in the Ti3C2O2 lattice, double TiO6 polyhedral are separated by the non-coplanar sp2 hybridized hexagon graphite layers along the c-axis, forming a sandwich-like structure. At ambient conditions, the two compounds are found to be mechanically and dynamically stable and intrinsic transparent conductors with high hardness (about twice harder than the conventional transparent conducting oxides). These mechanical, electronic, and optical properties make Ti5C2O6 and Ti3C2O2 ternary compounds be promising robust, hard, transparent, and conductive materials. PMID:25511583

A two step method to synthesize palladium-copper nanoparticles on reduced graphene oxide and their extremely high electrocatalytic activity for the electrooxidation of methanol and ethanol

NASA Astrophysics Data System (ADS)

Na, HeYa; Zhang, Lei; Qiu, HaiXia; Wu, Tao; Chen, MingXi; Yang, Nian; Li, LingZhi; Xing, FuBao; Gao, JianPing

2015-08-01

Palladium-copper nanoparticles (Pd-Cu NPs) supported on reduced graphene oxide (RGO) with different Pd/Cu ratios (Pd-Cu/RGO) were prepared by a two step method. The Pd-Cu/RGO hybrids were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and thermogravimetric analyses. Cyclic voltammetry and chronoamperometry were used to investigate the electrochemical activities and stabilities of the Pd-Cu/RGO catalysts for the electro-oxidation of methanol and ethanol in alkaline media. The Pd-Cu/RGO catalysts exhibited high catalytic activities and good stabilities. This is because the catalysts have a bimetallic structure consisting of a small Pd-Cu core surrounded by a thin Pd-rich shell which improves the catalytic activities of the Pd-Cu/RGO hybrids. Thus they should be useful in direct methanol and ethanol fuel cells.

Aligning Ag Nanowires by a Facile Bioinspired Directional Liquid Transfer: Toward Anisotropic Flexible Conductive Electrodes.

PubMed

Meng, Lili; Bian, Ruixin; Guo, Cheng; Xu, Bojie; Liu, Huan; Jiang, Lei

2018-06-01

Recent years have witnessed the booming development of transparent flexible electrodes (TFEs) for their applications in electronics and optoelectronic devices. Various strategies have thus been developed for preparing TFEs with higher flexibility and conductivity. However, little work has focused on TFEs with anisotropic conductivity. Here, a facile strategy of directional liquid transfer is proposed, guided by a conical fibers array (CFA), based on which silver nanowires (AgNWs) are aligned on a soft poly(ethylene terephthalate) substrate in large scale. After further coating a second thin layer of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), a TFE with notable anisotropic conductivity and excellent optical transmittance of 95.2% is prepared. It is proposed that the CFA enables fine control over the receding of the three-phase contact line during the dewetting process, where AgNWs are guided and aligned by the as-generated directional stress. Moreover, anisotropic electrochemical deposition is enabled where the Cu nanoparticles deposit only on the oriented AgNWs, leading to a surface with anisotropic wetting behavior. Importantly, the approach enables alignment of AgNWs via multiple directions at one step. It is envisioned that the as-developed approach will provide an optional approach for simple and low-cost preparation of TFE with various functions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Schottky junction interfacial properties at high temperature: A case of AgNWs embedded metal oxide/p-Si

NASA Astrophysics Data System (ADS)

Mahala, Pramila; Patel, Malkeshkumar; Gupta, Navneet; Kim, Joondong; Lee, Byung Ha

2018-05-01

Studying the performance limiting parameters of the Schottky device is an urgent issue, which are addressed herein by thermally stable silver nanowire (AgNW) embedded metal oxide/p-Si Schottky device. Temperature and bias dependent junction interfacial properties of AgNW-ITO/Si Schottky photoelectric device are reported. The current-voltage-temperature (I-V-T), capacitance-voltage-temperature (C-V-T) and impedance analysis have been carried out in the high-temperature region. The ideality factor and barrier height of Schottky junction are assessed using I-V-T characteristics and thermionic emission, to reveal the decrease of ideality factor and increase of barrier height by the increasing of temperature. The extracted values of laterally homogeneous Schottky (ϕb) and ideality factor (n) are approximately 0.73 eV and 1.58, respectively. Series resistance (Rs) assessed using Cheung's method and found that it decreases with the increase of temperature. A linear response of Rs of AgNW-ITO/Si Schottky junction is observed with respect to change in forward bias, i.e. dRS/dV from 0 to 0.7 V is in the range of 36.12-36.43 Ω with a rate of 1.44 Ω/V. Impedance spectroscopy is used to study the effect of bias voltage and temperature on intrinsic Schottky properties which are responsible for photoconversion efficiency. These systematic analyses are useful for the AgNWs-embedding Si solar cells or photoelectrochemical cells.

All-solid-state reduced graphene oxide supercapacitor with large volumetric capacitance and ultralong stability prepared by electrophoretic deposition method.

PubMed

Wang, Mei; Duong, Le Dai; Mai, Nguyen Thi; Kim, Sanghoon; Kim, Youngjun; Seo, Heewon; Kim, Ye Chan; Jang, Woojin; Lee, Youngkwan; Suhr, Jonghwan; Nam, Jae-Do

2015-01-21

Portable energy storage devices have gained special attention due to the growing demand for portable electronics. Herein, an all-solid-state supercapacitor is successfully fabricated based on a poly(vinyl alcohol)-H3PO4 (PVA-H3PO4) polymer electrolyte and a reduced graphene oxide (RGO) membrane electrode prepared by electrophoretic deposition (EPD). The RGO electrode fabricated by EPD contains an in-plane layer-by-layer alignment and a moderate porosity that accommodate the electrolyte ions. The all-solid-state RGO supercapacitor is thoroughly tested to give high specific volumetric capacitance (108 F cm(-3)) and excellent energy and power densities (7.5 Wh cm(-3) and 2.9 W cm(-3), respectively). In addition, the all-solid-state RGO supercapacitor exhibits an ultralong lifetime for as long as 180 days (335 000 cycles), which is an ultrahigh cycling capability for a solid-state supercapacitor. The RGO is also tested for being used as a transparent supercapacitor electrode demonstrating its possible use in various transparent optoelectronic devices. Due to the facile scale-up capability of the EPD process and RGO dispersion, the developed all-solid-state supercapacitor is highly applicable to large-area portable energy storage devices.

RGO/Au NPs/N-doped CNTs supported on nickel foam as an anode for enzymatic biofuel cells.

PubMed

Zhang, He; Zhang, Lingling; Han, Yujie; Yu, You; Xu, Miao; Zhang, Xueping; Huang, Liang; Dong, Shaojun

2017-11-15

In this study, three-dimensional reduced graphene oxide/Au NPs/nitrogen-doped carbon nanotubes (RGO/Au NPs/N-doped CNTs) assembly supported on nickel foam was utilized as an anode for enzymatic biofuel cells (EBFCs). 3D RGO/Au NPs was obtained by electrodepositing reduced graphene oxide on nickel foam (Ni foam), while Au NPs were co-deposited during the process. Afterwards, nitrogen doped CNTs (N-CNTs) were allowed to grow seamlessly on the surfaces of 3D RGO/Au NPs via a simple chemical vapor deposition (CVD) process. In this nanostructure, Au NPs co-deposition and nitrogen doping offer more active sites for bioelectrocatalysis. Additionally, N-CNTs were demonstrated providing high specific surface area for enzyme immobilization and facilitating the electron transfer between glucose oxidase (GOx) and electrode. The resulting bioanode achieved efficient glucose oxidation with high current densities of 7.02mAcm -2 (0.3V vs. Ag/AgCl). Coupling with a Pt cathode, the fabricated glucose/air biofuel cell exhibited an open-circuit potential of 0.32V and generated a maximum power density 235µWcm -2 at 0.15V. This novel electrode substrate achieved high performance in current density at bioelectrochemical systems and could be useful for further exploiting the application of three dimensional carbon-based nanomaterials in EBFCs. Copyright © 2017 Elsevier B.V. All rights reserved.

Degradation of trichloroethylene in aqueous solution by rGO supported nZVI catalyst under several oxic environments.

PubMed

Gu, Mengbin; Farooq, Usman; Lu, Shuguang; Zhang, Xiang; Qiu, Zhaofu; Sui, Qian

2018-05-05

The reduced graphene oxide (rGO) supported nano zero-valent iron (nZVI) (nZVI-rGO) was synthesized successfully and applied in the several oxic environments to remove trichloroethylene (TCE). The nZVI-rGO had a better catalytic performance than bare nZVI for the TCE removal. Both aggregation of nZVI and agglomeration of rGO were in part prevented by loading the nZVI nanoparticles on the rGO sheet. Among all the oxic environments, the better removal of TCE was followed as the order of PMS > SPS > H 2 O 2 . Chemical scavenger tests were carried out to identify the reactive oxygen species (ROSs) generated in the removal of TCE, showing that in PMS and SPS systems, SO 4 - and HO were main radicals responsible for TCE removal, while HO and O 2 - were main radicals in H 2 O 2 system. The possible mechanisms were proposed with nZVI-rGO under several oxic environments. The recyclability of nZVI-rGO, dechlorination and mineralization of TCE were investigated. These fundamental data confirmed the effectiveness of nZVI-rGO to remove TCE and could help selecting the suitable oxidants to use with nZVI-rGO in the actual field groundwater remediation. Copyright © 2018 Elsevier B.V. All rights reserved.

Bioinspired Transparent Laminated Composite Film for Flexible Green Optoelectronics.

PubMed

Lee, Daewon; Lim, Young-Woo; Im, Hyeon-Gyun; Jeong, Seonju; Ji, Sangyoon; Kim, Yong Ho; Choi, Gwang-Mun; Park, Jang-Ung; Lee, Jung-Yong; Jin, Jungho; Bae, Byeong-Soo

2017-07-19

Herein, we report a new version of a bioinspired chitin nanofiber (ChNF) transparent laminated composite film (HCLaminate) made of siloxane hybrid materials (hybrimers) reinforced with ChNFs, which mimics the nanofiber-matrix structure of hierarchical biocomposites. Our HCLaminate is produced via vacuum bag compressing and subsequent UV-curing of the matrix resin-impregnated ChNF transparent paper (ChNF paper). It is worthwhile to note that this new type of ChNF-based transparent substrate film retains the strengths of the original ChNF paper and compensates for ChNF paper's drawbacks as a flexible transparent substrate. As a result, compared with high-performance synthetic plastic films, such as poly(ethylene terephthalate), poly(ether sulfone), poly(ethylene naphthalate), and polyimide, our HCLaminate is characterized to exhibit extremely smooth surface topography, outstanding optical clarity, high elastic modulus, high dimensional stability, etc. To prove our HCLaminate as a substrate film, we use it to fabricate flexible perovskite solar cells and a touch-screen panel. As far as we know, this work is the first to demonstrate flexible optoelectronics, such as flexible perovskite solar cells and a touch-screen panel, actually fabricated on a composite film made of ChNF. Given its desirable macroscopic properties, we envision our HCLaminate being utilized as a transparent substrate film for flexible green optoelectronics.

A facile method of preparing LiMnPO4/reduced graphene oxide aerogel as cathodic material for aqueous lithium-ion hybrid supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Lin; Wang, Senlin; Zhang, Xiao; He, Taobin; Lu, Fengxia; Li, Huichang; Ye, Junhui

2018-01-01

A facile method of preparing LiMnPO4/reduced graphene oxide aerogel (LMP/rGO) as cathodic material was reported here. LiMnPO4 nano-particles were prepared using a facile polyvinyl pyrrolidone-assisted solvothermal route. Then LMP/rGO aerogel was prepared using the accessible restacking method. The influence of the cathodic electrode composition (ratio of rGO to LiMnPO4) on the performance of the LMP/rGO was evaluated by constant-current discharge tests. When compared with 217C g-1 for the pristine LMP, the best LMP/rGO (the content of rGO is 27.3 wt%) exhibits a higher capacity of 464.5C g-1 (at 0.5 A g-1), which presenting the capacity enhance of 114%. Moreover, a lithium-ion hybrid supercapacitor (LIHS) was successfully assembled by using LMP/rGO aerogel as the cathodic electrode and rGO aerogel as the anodic electrode. The LMP/rGO//rGO device achieves excellent specific energy of 16.46 W h kg-1 at a power density of 0.38 kW kg-1, even under the higher specific power of 4.52 kW kg-1, there still holds the specific energy of 11.79 W h kg-1. The LMP/rGO//rGO device maintains 91.2% of the initial capacity after 10,000 cycles (at 2 A g-1), which displays high rate performance and long cycle life. The 3D LMP/rGO aerogel could be a promising candidate material for the lithium-ion hybrid supercapacitors.

Graphene Oxide Transparent Hybrid Film and Its Ultraviolet Shielding Property.

PubMed

Xie, Siyuan; Zhao, Jianfeng; Zhang, Bowu; Wang, Ziqiang; Ma, Hongjuan; Yu, Chuhong; Yu, Ming; Li, Linfan; Li, Jingye

2015-08-19

Herein, we first reported a facile strategy to prepare functional Poly(vinyl alcohol) (PVA) hybrid film with well ultraviolet (UV) shielding property and visible light transmittance using graphene oxide nanosheets as UV-absorber. The absorbance of ultraviolet light at 300 nm can be up to 97.5%, while the transmittance of visible light at 500 nm keeps 40% plus. This hybrid film can protect protein from UVA light induced photosensitive damage, remarkably.

Cellulose nanofibril/reduced graphene oxide/carbon nanotube hybrid aerogels for highly flexible and all-solid-state supercapacitors.

PubMed

Zheng, Qifeng; Cai, Zhiyong; Ma, Zhenqiang; Gong, Shaoqin

2015-02-11

A novel type of highly flexible and all-solid-state supercapacitor that uses cellulose nanofibril (CNF)/reduced graphene oxide (RGO)/carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4/poly(vinyl alcohol) (PVA) gel as the electrolyte was developed and is reported here. These flexible solid-state supercapacitors were fabricated without any binders, current collectors, or electroactive additives. Because of the porous structure of the CNF/RGO/CNT aerogel electrodes and the excellent electrolyte absorption properties of the CNFs present in the aerogel electrodes, the resulting flexible supercapacitors exhibited a high specific capacitance (i.e., 252 F g(-1) at a discharge current density of 0.5 A g(-1)) and a remarkable cycle stability (i.e., more than 99.5% of the capacitance was retained after 1000 charge-discharge cycles at a current density of 1 A g(-1)). Furthermore, the supercapacitors also showed extremely high areal capacitance, areal power density, and energy density (i.e., 216 mF cm(-2), 9.5 mW cm(-2), and 28.4 μWh cm(-2), respectively). In light of its excellent electrical performance, low cost, ease of large-scale manufacturing, and environmental friendliness, the CNF/RGO/CNT aerogel electrodes may have a promising application in the development of flexible energy-storage devices.

Low-temperature-processed efficient semi-transparent planar perovskite solar cells for bifacial and tandem applications

PubMed Central

Fu, Fan; Feurer, Thomas; Jäger, Timo; Avancini, Enrico; Bissig, Benjamin; Yoon, Songhak; Buecheler, Stephan; Tiwari, Ayodhya N.

2015-01-01

Semi-transparent perovskite solar cells are highly attractive for a wide range of applications, such as bifacial and tandem solar cells; however, the power conversion efficiency of semi-transparent devices still lags behind due to missing suitable transparent rear electrode or deposition process. Here we report a low-temperature process for efficient semi-transparent planar perovskite solar cells. A hybrid thermal evaporation–spin coating technique is developed to allow the introduction of PCBM in regular device configuration, which facilitates the growth of high-quality absorber, resulting in hysteresis-free devices. We employ high-mobility hydrogenated indium oxide as transparent rear electrode by room-temperature radio-frequency magnetron sputtering, yielding a semi-transparent solar cell with steady-state efficiency of 14.2% along with 72% average transmittance in the near-infrared region. With such semi-transparent devices, we show a substantial power enhancement when operating as bifacial solar cell, and in combination with low-bandgap copper indium gallium diselenide we further demonstrate 20.5% efficiency in four-terminal tandem configuration. PMID:26576667

Low-temperature-processed efficient semi-transparent planar perovskite solar cells for bifacial and tandem applications.

PubMed

Fu, Fan; Feurer, Thomas; Jäger, Timo; Avancini, Enrico; Bissig, Benjamin; Yoon, Songhak; Buecheler, Stephan; Tiwari, Ayodhya N

2015-11-18

Semi-transparent perovskite solar cells are highly attractive for a wide range of applications, such as bifacial and tandem solar cells; however, the power conversion efficiency of semi-transparent devices still lags behind due to missing suitable transparent rear electrode or deposition process. Here we report a low-temperature process for efficient semi-transparent planar perovskite solar cells. A hybrid thermal evaporation-spin coating technique is developed to allow the introduction of PCBM in regular device configuration, which facilitates the growth of high-quality absorber, resulting in hysteresis-free devices. We employ high-mobility hydrogenated indium oxide as transparent rear electrode by room-temperature radio-frequency magnetron sputtering, yielding a semi-transparent solar cell with steady-state efficiency of 14.2% along with 72% average transmittance in the near-infrared region. With such semi-transparent devices, we show a substantial power enhancement when operating as bifacial solar cell, and in combination with low-bandgap copper indium gallium diselenide we further demonstrate 20.5% efficiency in four-terminal tandem configuration.

Generation of tunable double Fano resonances by plasmon hybridization in graphene–metal metamaterial

NASA Astrophysics Data System (ADS)

Yan, Zhendong; Qian, Lina; Zhan, Peng; Wang, Zhenlin

2018-07-01

We proposed the excitation of double Fano resonances by the destructive interference between the narrow electric symmetric/antisymmetric resonant modes formed by plasmon hybridization and a broad magnetic dipole resonance in a novel hybrid metamaterial composed of periodically patterned stacked graphene–ribbon pairs and gold split-ring resonators. The double Fano transparency windows in this hybrid metamaterial can be actively controlled by tuning the Fermi energy of graphene through the use of electric gating and its electronic mobility. Our designed dual Fano resonances exhibit a large group index associated with the resonance response in the transparency windows, suggesting promising applications in nanophotonics, such as a slow light device.

Pyrochlore Ce2Zr2O7 decorated over rGO: a photocatalyst that proves to be efficient towards the reduction of 4-nitrophenol and degradation of ciprofloxacin under visible light.

PubMed

Mansingh, Sriram; Acharya, Rashmi; Martha, Satyabadi; Parida, K M

2018-04-18

In the present study, a series of Ce2Zr2O7@rGO nanocomposites were synthesized using a simple solution combustion method followed by a photoreduction technique. The as-prepared samples were well characterised using various analytical techniques to determine the morphological, optical, structural, electrochemical and compositional properties. The presence of oxygen defects was observed from Raman and photoluminescence spectra. The photoreduction of GO to rGO was determined from Raman and Fourier-transform infrared (FTIR) spectroscopy results. The role of rGO proved to be quite significant for the enhanced photocatalytic activity of the nanocomposites. The synergistic communication between Ce2Zr2O7 and rGO accelerates the photoreduction of 4-nitrophenol along with the degradation of ciprofloxacin under visible light irradiation. Of the rGO nanocomposites, 3 wt% GO loaded Ce2Zr2O7 reduces 99% of 20 ppm of 4-nitrophenol to 4-aminophenol in 120 min and decomposes 10 ppm of ciprofloxacin by up to 89% in 60 min. The significant enhancement in the activity of the Ce2Zr2O7@rGO nanocomposite was ascribed to the effective charge separation of excitons through π-conjugation of graphene at the interface, which is well supported by the impedance, photoluminescence and photocatalytic results.

Flexible transparent aerogels as window retrofitting films and optical elements with tunable birefringence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Qingkun; Frazier, Allister W.; Zhao, Xinpeng

Experimental realization of optically transparent, mechanically robust and flexible aerogels has been a longstanding challenge, which limits their practical applications in energy-saving devices, such as thermally insulating films for enhancing energy efficiency of windows. The poor transparency precluded even hypothetical consideration of the possibility of birefringent aerogels. We develop birefringent and optically isotropic aerogels that combine properties of thermal super-insulation, mechanical robustness and flexibility, and transparency to visible-spectrum light. This unusual combination of physical properties is achieved by combining liquid crystalline self-organization of cellulose nanofibers with polysiloxane cross-linking and control of the nanoscale porosity to form hybrid organic-inorganic mesostructured aerogels.more » Potential applications of these inexpensive materials range from single pane window retrofitting to smart fabrics.« less

Preparation of Transparent Bulk TiO2/PMMA Hybrids with Improved Refractive Indices via an in Situ Polymerization Process Using TiO2 Nanoparticles Bearing PMMA Chains Grown by Surface-Initiated Atom Transfer Radical Polymerization.

PubMed

Maeda, Satoshi; Fujita, Masato; Idota, Naokazu; Matsukawa, Kimihiro; Sugahara, Yoshiyuki

2016-12-21

Transparent TiO 2 /PMMA hybrids with a thickness of 5 mm and improved refractive indices were prepared by in situ polymerization of methyl methacrylate (MMA) in the presence of TiO 2 nanoparticles bearing poly(methyl methacrylate) (PMMA) chains grown using surface-initiated atom transfer radical polymerization (SI-ATRP), and the effect of the chain length of modified PMMA on the dispersibility of modified TiO 2 nanoparticles in the bulk hybrids was investigated. The surfaces of TiO 2 nanoparticles were modified with both m-(chloromethyl)phenylmethanoyloxymethylphosphonic acid bearing a terminal ATRP initiator and isodecyl phosphate with a high affinity for common organic solvents, leading to sufficient dispersibility of the surface-modified particles in toluene. Subsequently, SI-ATRP of MMA was achieved from the modified surfaces of the TiO 2 nanoparticles without aggregation of the nanoparticles in toluene. The molecular weights of the PMMA chains cleaved from the modified TiO 2 nanoparticles increased with increases in the prolonging of the polymerization period, and these exhibited a narrow distribution, indicating chain growth controlled by SI-ATRP. The nanoparticles bearing PMMA chains were well-dispersed in MMA regardless of the polymerization period. Bulk PMMA hybrids containing modified TiO 2 nanoparticles with a thickness of 5 mm were prepared by in situ polymerization of the MMA dispersion. The transparency of the hybrids depended significantly on the chain length of the modified PMMA on the nanoparticles, because the modified PMMA of low molecular weight induced aggregation of the TiO 2 nanoparticles during the in situ polymerization process. The refractive indices of the bulk hybrids could be controlled by adjusting the TiO 2 content and could be increased up to 1.566 for 6.3 vol % TiO 2 content (1.492 for pristine PMMA).

Electrical properties of films of zinc oxide nanoparticles and its hybrid with reduced graphene oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madhuri, K. Priya; Bramhaiah, K.; John, Neena S., E-mail: jsneena@cnsms.res.in

Free-standing films of ZnO nanoparticles (NPs) and reduced graphene oxide (rGO)-ZnO NPs hybrid are prepared at a liquid/liquid interface. The films are characterized by UV-visible spectroscopy, X-ray diffraction, scanning electron microscopy and atomic force microscopy. ZnO film consists of spherical aggregated NPs while the hybrid film contains folded sheets of rGO with embedded ZnO NPs. Electrical properties of the films and its photoresponse in presence of UV radiation are investigated using current sensing atomic force microscopy (CSAFM) at nanoscale and bulk measurements using two probe methods. Enhancement in photocurrent is observed in both cases and the current imaging reveals anmore » inhomogeneous contribution by different ZnO grains in the film.« less

Hybrid sol-gel optical materials

DOEpatents

Zeigler, J.M.

1993-04-20

Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

Hybrid sol-gel optical materials

DOEpatents

Zeigler, John M.

1993-01-01

Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

Hybrid sol-gel optical materials

DOEpatents

Zeigler, John M.

1992-01-01

Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

Construction of a 3D rGO-collagen hybrid scaffold for enhancement of the neural differentiation of mesenchymal stem cells

NASA Astrophysics Data System (ADS)

Guo, Weibo; Wang, Shu; Yu, Xin; Qiu, Jichuan; Li, Jianhua; Tang, Wei; Li, Zhou; Mou, Xiaoning; Liu, Hong; Wang, Zhonglin

2016-01-01

The cell-material interface is one of the most important considerations in designing a high-performance tissue engineering scaffold because the surface of the scaffold can determine the fate of stem cells. A conductive surface is required for a scaffold to direct stem cells toward neural differentiation. However, most conductive polymers are toxic and not amenable to biological degradation, which restricts the design of neural tissue engineering scaffolds. In this study, we used a bioactive three-dimensional (3D) porcine acellular dermal matrix (PADM), which is mainly composed of type I collagen, as a basic material and successfully assembled a layer of reduced graphene oxide (rGO) nanosheets on the surface of the PADM channels to obtain a porous 3D, biodegradable, conductive and biocompatible PADM-rGO hybrid neural tissue engineering scaffold. Compared with the PADM scaffold, assembling the rGO into the scaffold did not induce a significant change in the microstructure but endowed the PADM-rGO hybrid scaffold with good conductivity. A comparison of the neural differentiation of rat bone-marrow-derived mesenchymal stem cells (MSCs) was performed by culturing the MSCs on PADM and PADM-rGO scaffolds in neuronal culture medium, followed by the determination of gene expression and immunofluorescence staining. The results of both the gene expression and protein level assessments suggest that the rGO-assembled PADM scaffold may promote the differentiation of MSCs into neuronal cells with higher protein and gene expression levels after 7 days under neural differentiation conditions. This study demonstrated that the PADM-rGO hybrid scaffold is a promising scaffold for neural tissue engineering; this scaffold can not only support the growth of MSCs at a high proliferation rate but also enhance the differentiation of MSCs into neural cells.The cell-material interface is one of the most important considerations in designing a high-performance tissue engineering scaffold

Photocatalytic growth of Ag nanocrystals on hydrothermally synthesized multiphasic TiO2/reduced graphene oxide (rGO) nanocomposites and their SERS performance

NASA Astrophysics Data System (ADS)

Guo, Tian-Long; Li, Ji-Guang; Sun, Xudong; Sakka, Yoshio

2017-11-01

TiO2/reduced graphene oxide (rGO) nanocomposites were prepared via a facile one-step hydrothermal method using TiCl3 as the TiO2 precursor. Cetyltrimethyl ammonium bromide (CTAB) was introduced as a stabilizer for GO in solution. The effects of GO content, Ti3+ concentration and urea additive on phase constituent and morphology of the TiO2 crystallites in the nanocomposites were systematically investigated. UV-vis absorption ability of the as-made composites was further tested and discussed. Ag nanocrystals (NCs) were photocatalytically grown on the surfaces of biphasic (anatase + brookite) and triphasic (anatase + brookite + rutile) TiO2/rGO nanocomposites to evaluate their surface-enhanced Raman scattering (SERS) performances. Morphology evolution of the Ag NCs in response to different photocatalytic ability of the TiO2/rGO nanocomposite was also investigated in detail. The nanocomposite with triphasic TiO2 of proper phase constituents was confirmed to favor the growth of Ag particles of two distinctly different sizes and to produce SERS substrates of substantially better performance.

Study of GO-Cu2O and RGO-Cu nanocomposite monolayer sheets prepared by modified Langmuir Blodgett route

NASA Astrophysics Data System (ADS)

Botcha, V. Divakar; Sutar, D. S.; Major, S. S.

2018-07-01

The modified Langmuir-Blodgett (MLB) technique has been improvised and extended to transfer GO-Cu2O nanocomposite monolayer sheets, by introducing Cu2+ ions into the subphase at room temperature. Morphological studies of as-transferred sheets revealed the presence of closely spaced GO monolayer sheets, with slightly enhanced roughness. XPS studies of as-transferred sheets confirmed the presence of copper, either as metallic Cu or Cu2O, along with significant Cu(OH)2 component, but TEM results confirmed the formation of Cu2O nanocrystallites of size (7 ± 2) nm, distributed uniformly over GO sheets. After heat treatment in vacuum at 400 °C, the nanocomposite sheets were covered with a uniform distribution of larger size nanoparticles. Based on Raman, XPS and TEM studies it has been confirmed that heat treatment at 400 °C in vacuum results in the formation of agglomerated Cu nanoparticles of size (23 ± 9) nm distributed uniformly over reduced graphene oxide (RGO) sheets. The electrical characterization of nanocomposite sheets on SiO2/Si in back-gated FET geometry revealed that the electrical conductivity of as-transferred GO-Cu2O sheets was similar to that usually observed for GO monolayer sheets. The RGO-Cu sheets also displayed electrical conductivity and field effect mobility values comparable to those reported for RGO sheets obtained by chemical/thermal reduction, and was unaffected by the presence of Cu nanoparticles.

Spin injection and detection in lateral spin valves with hybrid interfaces

NASA Astrophysics Data System (ADS)

Wang, Le; Liu, Wenyu; Ying, Hao; Chen, Luchen; Lu, Zhanjie; Han, Shuo; Chen, Shanshan; Zhao, Bing; Xu, Xiaoguang; Jiang, Yong

2018-06-01

Spin injection and detection in lateral spin valves with hybrid interfaces comprising a Co/Ag transparent contact and a Co/MgO/Ag junction (III) are investigated at room temperature in comparison with pure Co/Ag transparent contacts (I) and Co/MgO/Ag junctions (II). The measured spin-accumulation signals of a type III device are five times higher than those for type I. The extracted spin diffusion length in Ag is 180 nm for all three types of devices. The enhancement of the spin signal of the hybrid structure is mainly attributed to the increase of the interfacial spin polarization from the Co/MgO/Ag junction.

High performance of visible-NIR broad spectral photocurrent application of monodisperse PbSe nanocubes decorated on rGO sheets

NASA Astrophysics Data System (ADS)

Ghorban Shiravizadeh, A.; Elahi, S. M.; Sebt, S. A.; Yousefi, Ramin

2018-02-01

In this work, the photoresponse performance of monodisperse PbSe nanocubes in the range of visible and near-infrared (NIR) (400-1500 nm) regions was enhanced by reduced graphene oxide (rGO). A simple cost-effective method is presented to synthesize monodisperse PbSe nanocubes (NCs) that are decorated on the rGO sheets. By the addition of PbSe/rGO nanocomposites with different rGO concentrations, pristine PbSe NCs were synthesized with the same method. Microscopy images showed that the size of NCs was smaller than the exciton Bohr radius (46 nm) of PbSe bulk. Therefore, the UV-Vis-IR spectroscopy result revealed that the PbSe/rGO samples had absorption peaks in the NIR region around 1650 nm and showed a blue shift compared to the absorption peak of the PbSe bulk. J-V measurements of the samples indicated that monodisperse PbSe/rGO nanocomposites had a higher resistance than the other samples under dark condition. On the other hand, the resistance of the monodisperse PbSe/rGO nanocomposites decreased under different light source illuminations while the resistance of the other samples was increased under illumination. Photodetector measurements indicated that the monodisperse morphology of the PbSe NCs enhanced the photoresponse speed and photocurrent intensity. In addition, responsivity (R) and detectivity (D*) of the samples were higher in the NIR region.

Effect of lithium and sodium salt on the performance of Nb2O5/rGO nanocomposite based supercapacitor

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Rafat, M.

2018-03-01

The present work reports the synthesis of Nb2O5/rGO composite using hydrothermal method and thermal annealing process. The prepared composite was found to have suitable characteristics necessary to be used as electrode material in supercapacitors. These characteristics were ascertained employing the techniques of scanning electron microscopy (SEM), x-ray diffraction (XRD), Raman spectroscopy and N2 adsorption-desorption isotherm. Further, the electrochemical performance of the prepared composite was compared in two different organic electrolytes, of lithium and sodium salt using the techniques of electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and charge-discharge measurements. The organic electrolyte solutions were prepared by dispersing 1 M LiClO4/NaClO4 in a mixture of ethylene carbonate/propylene carbonate (1:1 by volume). The observed results indicate that the composite of Nb2O5/rGO offers higher value of specific capacitance in sodium salt electrolyte and higher cyclic stability in lithium salt electrolyte. This is probably due to ion properties of electrolyte. Specific capacitance is observed according to efficient ion/charge diffusion/exchange and relaxation time (Li+ < Na+), while the cyclic stability is observed according to cation size (Na+ > Li+). Thus, the present study reveals the significant effect of electrolyte ions on electrochemical performance of Nb2O5/rGO composite.

76 FR 1180 - FDA Transparency Initiative: Improving Transparency to Regulated Industry

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-07

...] FDA Transparency Initiative: Improving Transparency to Regulated Industry AGENCY: Food and Drug... the Transparency Initiative, the Food and Drug Administration (FDA) is announcing the availability of a report entitled ``FDA Transparency Initiative: Improving Transparency to Regulated Industry.'' The...

A high-performance, flexible and robust metal nanotrough-embedded transparent conducting film for wearable touch screen panels

NASA Astrophysics Data System (ADS)

Im, Hyeon-Gyun; An, Byeong Wan; Jin, Jungho; Jang, Junho; Park, Young-Geun; Park, Jang-Ung; Bae, Byeong-Soo

2016-02-01

We report a high-performance, flexible and robust metal nanotrough-embedded transparent conducting hybrid film (metal nanotrough-GFRHybrimer). Using an electro-spun polymer nanofiber web as a template and vacuum-deposited gold as a conductor, a junction resistance-free continuous metal nanotrough network is formed. Subsequently, the metal nanotrough is embedded on the surface of a glass-fabric reinforced composite substrate (GFRHybrimer). The monolithic composite structure of our transparent conducting film allows simultaneously high thermal stability (24 h at 250 °C in air), a smooth surface topography (Rrms < 1 nm) and excellent opto-electrical properties. A flexible touch screen panel (TSP) is fabricated using the transparent conducting films. The flexible TSP device stably operates on the back of a human hand and on a wristband.We report a high-performance, flexible and robust metal nanotrough-embedded transparent conducting hybrid film (metal nanotrough-GFRHybrimer). Using an electro-spun polymer nanofiber web as a template and vacuum-deposited gold as a conductor, a junction resistance-free continuous metal nanotrough network is formed. Subsequently, the metal nanotrough is embedded on the surface of a glass-fabric reinforced composite substrate (GFRHybrimer). The monolithic composite structure of our transparent conducting film allows simultaneously high thermal stability (24 h at 250 °C in air), a smooth surface topography (Rrms < 1 nm) and excellent opto-electrical properties. A flexible touch screen panel (TSP) is fabricated using the transparent conducting films. The flexible TSP device stably operates on the back of a human hand and on a wristband. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07657a

In situ X-ray diffraction characterization of NiSe2 as a promising anode material for sodium ion batteries

NASA Astrophysics Data System (ADS)

Ou, Xing; Li, Jiao; Zheng, Fenghua; Wu, Peng; Pan, Qichang; Xiong, Xunhui; Yang, Chenghao; Liu, Meilin

2017-03-01

Reduced graphene oxide (rGO) homogenously wrapped nickel diselenide (NiSe2/rGO) hybrid has been prepared by a facile one-spot hydrothermal method. When investigated as anode material for sodium ion batteries (SIBs), NiSe2/rGO hybrid delivers a high reversible capacity (433 mAh g-1 at 100 mA g-1), superior rate performance (406, 386, 366, 347 and 318 mAh g-1 at 200, 500, 1000, 2000 and 5000 mA g-1, respectively) and excellent cycling stability (a capacity retention of 346 mAh g-1 after 1000 cycles at 1000 mA g-1) within the 0.4-3.0 V voltage range. In situ XRD analysis and ex situ SEM/TEM measurement reveal that the high capacity of NiSe2/rGO is originated from the combined Na+ intercalation and conversion reactions. These results validate the impact of voltage range on electrochemical property, providing a new route to rationalize the limiting factors that affect the performance of NiSe2 anode material. The facile synthesis and superior electrochemical performance of the NiSe2/rGO hybrid render it a promising anode material for SIBs.

Ultra-high aspect ratio copper nanowires as transparent conductive electrodes for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Zhu, Zhaozhao; Mankowski, Trent; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

2016-09-01

We report the synthesis of ultra-high aspect ratio copper nanowires (CuNW) and fabrication of CuNW-based transparent conductive electrodes (TCE) with high optical transmittance (>80%) and excellent sheet resistance (Rs <30 Ω/sq). These CuNW TCEs are subsequently hybridized with aluminum-doped zinc oxide (AZO) thin-film coatings, or platinum thin film coatings, or nickel thin-film coatings. Our hybrid transparent electrodes can replace indium tin oxide (ITO) films in dye-sensitized solar cells (DSSCs) as either anodes or cathodes. We highlight the challenges of integrating bare CuNWs into DSSCs, and demonstrate that hybridization renders the solar cell integrations feasible. The CuNW/AZO-based DSSCs have reasonably good open-circuit voltage (Voc = 720 mV) and short-circuit current-density (Jsc = 0.96 mA/cm2), which are comparable to what is obtained with an ITO-based DSSC fabricated with a similar process. Our CuNW-Ni based DSSCs exhibit a good open-circuit voltage (Voc = 782 mV) and a decent short-circuit current (Jsc = 3.96 mA/cm2), with roughly 1.5% optical-to-electrical conversion efficiency.

Preparation of surface modified TiO2/rGO microspheres and application in the photocatalytic decomposition of oleic acid

NASA Astrophysics Data System (ADS)

Wu, Xin; Zeng, Min; Tong, Xiaoling; Li, Fuyun; Xu, Youyou

2018-05-01

The comprehensive utilization of waste cooking oil is an important research topic in food science. In this study, the surface modified mesoporous anatase TiO2/reduced graphene oxide (rGO) microspheres with a high specific surface area have been successfully synthesized, through hydrothermal routes and hydrazine reduced graphene oxide. The photocatalytic decomposition of waste rapeseed oil has also been studied using TiO2/rGO microspheres as photocatalyst. The result shows that the reduced graphene oxide in these nanocomposites can act as adsorbent and photocatalyst, and the temperature and the oxygen amount also are the most important factors affecting the oleic acid decomposition products. There interesting results not only helpful for the study of the mechanism of photocatalytic, but also useful for the rational use of waste cooking oil.

Electrophoretic build-up of alternately multilayered films and micropatterns based on graphene sheets and nanoparticles and their applications in flexible supercapacitors.

PubMed

Niu, Zhiqiang; Du, Jianjun; Cao, Xuebo; Sun, Yinghui; Zhou, Weiya; Hng, Huey Hoon; Ma, Jan; Chen, Xiaodong; Xie, Sishen

2012-10-22

Graphene nanosheets and metal nanoparticles (NPs) have been used as nano-building-blocks for assembly into macroscale hybrid structures with promising performance in electrical devices. However, in most graphene and metal NP hybrid structures, the graphene sheets and metal NPs (e.g., AuNPs) do not enable control of the reaction process, orientation of building blocks, and organization at the nanoscale. Here, an electrophoretic layer-by-layer assembly for constructing multilayered reduced graphene oxide (RGO)/AuNP films and lateral micropatterns is presented. This assembly method allows easy control of the nano-architecture of building blocks along the normal direction of the film, including the number and thickness of RGO and AuNP layers, in addition to control of the lateral orientation of the resultant multilayered structures. Conductivity of multilayered RGO/AuNP hybrid nano-architecture shows great improvement caused by a bridging effect of the AuNPs along the out-of-plane direction between the upper and lower RGO layers. The results clearly show the potential of electrophoretic build-up in the fabrication of graphene-based alternately multilayered films and patterns. Finally, flexible supercapacitors based on multilayered RGO/AuNP hybrid films are fabricated, and excellent performance, such as high energy and power densities, are achieved. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transparent bulk-size nanocomposites with high inorganic loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Shi; Gaume, Romain, E-mail: gaume@ucf.edu; Department of Materials Science and Engineering, University of Central Florida, Orlando, Florida 32816

2015-12-14

With relatively high nanoparticle loading in polymer matrices, hybrid nanocomposites made by colloidal dispersion routes suffer from severe inhomogeneous agglomeration, a phenomenon that deteriorates light transmission even when the refractive indices of the inorganic and organic phases are closely matched. The dispersion of particles in a matrix is of paramount importance to obtain composites of high optical quality. Here, we describe an innovative, yet straightforward method to fabricate monolithic transparent hybrid nanocomposites with very high particle loading and high refractive index mismatch tolerance between the inorganic and organic constituents. We demonstrate 77% transmission at 800 nm in a 2 mm-thick acrylate polymermore » nanocomposite containing 61 vol. % CaF{sub 2} nanoparticles. Modeling shows that similar performance could easily be obtained with various inorganic phases relevant to a number of photonic applications.« less

Covalent functionalization of graphene by azobenzene with molecular hydrogen bonds for long-term solar thermal storage

NASA Astrophysics Data System (ADS)

Feng, Yiyu; Liu, Hongpo; Luo, Wen; Liu, Enzuo; Zhao, Naiqin; Yoshino, Katsumi; Feng, Wei

2013-11-01

Reduced graphene oxide-azobenzene (RGO-AZO) hybrids were prepared via covalent functionalization for long-term solar thermal storage. Thermal barrier (ΔEa) of cis to tran reversion and thermal storage (ΔH) were improved by molecular hydrogen bonds (H-bonds) through ortho- or para-substitution of AZO. Intramolecular H-bonds thermally stabilized cis-ortho-AZO on RGO with a long-term half-life of 5400 h (ΔEa = 1.2 eV), which was much longer than that of RGO-para-AZO (116 h). RGO-para-AZO with one intermolecular H-bond showed a high density of thermal storage up to 269.8 kJ kg-1 compared with RGO-ortho-AZO (149.6 kJ kg-1) with multiple intra- and intermolecular H-bonds of AZO according to relaxed stable structures. Thermal storage in experiment was the same order magnitude to theoretical data based on ΔH calculated by density functional theory and packing density. Photoactive RGO-AZO hybrid can be developed for high-performance solar thermal storage by optimizing molecular H-bonds.

Covalent functionalization of graphene by azobenzene with molecular hydrogen bonds for long-term solar thermal storage

PubMed Central

Feng, Yiyu; Liu, Hongpo; Luo, Wen; Liu, Enzuo; Zhao, Naiqin; Yoshino, Katsumi; Feng, Wei

2013-01-01

Reduced graphene oxide-azobenzene (RGO-AZO) hybrids were prepared via covalent functionalization for long-term solar thermal storage. Thermal barrier (ΔEa) of cis to tran reversion and thermal storage (ΔH) were improved by molecular hydrogen bonds (H-bonds) through ortho- or para-substitution of AZO. Intramolecular H-bonds thermally stabilized cis-ortho-AZO on RGO with a long-term half-life of 5400 h (ΔEa = 1.2 eV), which was much longer than that of RGO-para-AZO (116 h). RGO-para-AZO with one intermolecular H-bond showed a high density of thermal storage up to 269.8 kJ kg−1 compared with RGO-ortho-AZO (149.6 kJ kg−1) with multiple intra- and intermolecular H-bonds of AZO according to relaxed stable structures. Thermal storage in experiment was the same order magnitude to theoretical data based on ΔH calculated by density functional theory and packing density. Photoactive RGO-AZO hybrid can be developed for high-performance solar thermal storage by optimizing molecular H-bonds. PMID:24247355

Covalent functionalization of graphene by azobenzene with molecular hydrogen bonds for long-term solar thermal storage.

PubMed

Feng, Yiyu; Liu, Hongpo; Luo, Wen; Liu, Enzuo; Zhao, Naiqin; Yoshino, Katsumi; Feng, Wei

2013-11-19

Reduced graphene oxide-azobenzene (RGO-AZO) hybrids were prepared via covalent functionalization for long-term solar thermal storage. Thermal barrier (ΔEa) of cis to tran reversion and thermal storage (ΔH) were improved by molecular hydrogen bonds (H-bonds) through ortho- or para-substitution of AZO. Intramolecular H-bonds thermally stabilized cis-ortho-AZO on RGO with a long-term half-life of 5400 h (ΔEa = 1.2 eV), which was much longer than that of RGO-para-AZO (116 h). RGO-para-AZO with one intermolecular H-bond showed a high density of thermal storage up to 269.8 kJ kg(-1) compared with RGO-ortho-AZO (149.6 kJ kg(-1)) with multiple intra- and intermolecular H-bonds of AZO according to relaxed stable structures. Thermal storage in experiment was the same order magnitude to theoretical data based on ΔH calculated by density functional theory and packing density. Photoactive RGO-AZO hybrid can be developed for high-performance solar thermal storage by optimizing molecular H-bonds.

Three-dimensional Nitrogen-Doped Graphene Supported Molybdenum Disulfide Nanoparticles as an Advanced Catalyst for Hydrogen Evolution Reaction

PubMed Central

Dong, Haifeng; Liu, Conghui; Ye, Haitao; Hu, Linping; Fugetsu, Bunshi; Dai, Wenhao; Cao, Yu; Qi, Xueqiang; Lu, Huiting; Zhang, Xueji

2015-01-01

An efficient three-dimensional (3D) hybrid material of nitrogen-doped graphene sheets (N-RGO) supporting molybdenum disulfide (MoS2) nanoparticles with high-performance electrocatalytic activity for hydrogen evolution reaction (HER) is fabricated by using a facile hydrothermal route. Comprehensive microscopic and spectroscopic characterizations confirm the resulting hybrid material possesses a 3D crumpled few-layered graphene network structure decorated with MoS2 nanoparticles. Electrochemical characterization analysis reveals that the resulting hybrid material exhibits efficient electrocatalytic activity toward HER under acidic conditions with a low onset potential of 112 mV and a small Tafel slope of 44 mV per decade. The enhanced mechanism of electrocatalytic activity has been investigated in detail by controlling the elemental composition, electrical conductance and surface morphology of the 3D hybrid as well as Density Functional Theory (DFT) calculations. This demonstrates that the abundance of exposed active sulfur edge sites in the MoS2 and nitrogen active functional moieties in N-RGO are synergistically responsible for the catalytic activity, whilst the distinguished and coherent interface in MoS2/N-RGO facilitates the electron transfer during electrocatalysis. Our study gives insights into the physical/chemical mechanism of enhanced HER performance in MoS2/N-RGO hybrids and illustrates how to design and construct a 3D hybrid to maximize the catalytic efficiency. PMID:26639026

Multi-slice nanostructured WS2@rGO with enhanced Li-ion battery performance and a comprehensive mechanistic investigation.

PubMed

Li, Honglin; Yu, Ke; Fu, Hao; Guo, Bangjun; Lei, Xiang; Zhu, Ziqiang

2015-11-28

A thin nanoslice structured WS2@reduced graphene oxide (rGO) composite was successfully fabricated by a facile hydrothermal synthesis method. The layered structure and morphology of the composite were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The WS2@rGO composite structure demonstrated significantly enhanced rate capability performance in comparison with pristine WS2 when used as an anode material for lithium-ion batteries (LIBs). The composite demonstrated a capacity of 565 mA h g(-1) after 100 cycles when cycled at 0.1 A g(-1) and it could still deliver a stable capacity of about 337 mA h g(-1) at 2 A g(-1). Electrochemical impedance spectroscopy (EIS) measurement showed that the synergistic effect between WS2 and rGO could remarkably reduce the contact resistance and improve the corresponding electrochemical performances. In order to analyze and interpret the corresponding results from a theoretically sound perspective, first principles calculations was further performed to investigate the corresponding inner mechanisms of pristine WS2 and WS2@graphene composite. The nudged elastic band (NEB) method was used to investigate the diffusion properties of Li in the different structures. Molecular dynamics (MD) simulation and Young's modulus calculation were further employed to explore the stability and mechanical properties of the two structures for the first time. These new perspectives pave the way for the design and fabrication of graphene-TMDs based composites as the next generation of LIB anode materials with high power density and cycling stability.

Improvement of the photovoltaic parameters of perovskite solar cells using a reduced-graphene-oxide-modified titania layer and soluble copper phthalocyanine as a hole transporter.

PubMed

Nouri, Esmaiel; Mohammadi, Mohammad Reza; Xu, Zong-Xiang; Dracopoulos, Vassilios; Lianos, Panagiotis

2018-01-24

Functional perovskite solar cells can be made by using a simple, inexpensive and stable soluble tetra-n-butyl-substituted copper phthalocyanine (CuBuPc) as a hole transporter. In the present study, TiO 2 /reduced graphene oxide (T/RGO) hybrids were synthesized via an in situ solvothermal process and used as electron acceptor/transport mediators in mesoscopic perovskite solar cells based on soluble CuBuPc as a hole transporter and on graphene oxide (GO) as a buffer layer. The impact of the RGO content on the optoelectronic properties of T/RGO hybrids and on the solar cell performance was studied, suggesting improved electron transport characteristics and photovoltaic parameters. An enhanced electron lifetime and recombination resistance led to an increase in the short circuit current density, open circuit voltage and fill factor. The device based on a T/RGO mesoporous layer with an optimal RGO content of 0.2 wt% showed 22% higher photoconversion efficiency and higher stability compared with pristine TiO 2 -based devices.

One-step hydrothermal synthesis of 3D petal-like Co9S8/RGO/Ni3S2 composite on nickel foam for high-performance supercapacitors.

PubMed

Zhang, Zhuomin; Wang, Qian; Zhao, Chongjun; Min, Shudi; Qian, Xiuzhen

2015-03-04

Co9S8, Ni3S2, and reduced graphene oxide (RGO) were combined to construct a graphene composite with two mixed metal sulfide components. Co9S8/RGO/Ni3S2 composite films were hydrothermal-assisted synthesized on nickel foam (NF) by using a modified "active metal substrate" route in which nickel foam acted as both a substrate and Ni source for composite films. It is found that the Co9S8/RGO/Ni3S2/NF electrode exhibits superior capacitive performance with high capability (13.53 F cm(-2) at 20 mA cm(-2), i.e., 2611.9 F g(-1) at 3.9 A g(-1)), excellent rate capability, and enhanced electrochemical stability, with 91.7% retention after 1000 continuous charge-discharge cycles even at a high current density of 80 mA cm(-2).

Hybrid Elastin-like Polypeptide–Polyethylene Glycol (ELP-PEG) Hydrogels with Improved Transparency and Independent Control of Matrix Mechanics and Cell Ligand Density

PubMed Central

2015-01-01

Hydrogels have been developed as extracellular matrix (ECM) mimics both for therapeutic applications and basic biological studies. In particular, elastin-like polypeptide (ELP) hydrogels, which can be tuned to mimic several biochemical and physical characteristics of native ECM, have been constructed to encapsulate various types of cells to create in vitro mimics of in vivo tissues. However, ELP hydrogels become opaque at body temperature because of ELP’s lower critical solution temperature behavior. This opacity obstructs light-based observation of the morphology and behavior of encapsulated cells. In order to improve the transparency of ELP hydrogels for better imaging, we have designed a hybrid ELP-polyethylene glycol (PEG) hydrogel system that rapidly cross-links with tris(hydroxymethyl) phosphine (THP) in aqueous solution via Mannich-type condensation. As expected, addition of the hydrophilic PEG component significantly improves the light transmittance. Coherent anti-Stokes Raman scattering (CARS) microscopy reveals that the hybrid ELP-PEG hydrogels have smaller hydrophobic ELP aggregates at 37 °C. Importantly, this hydrogel platform enables independent tuning of adhesion ligand density and matrix stiffness, which is desirable for studies of cell–matrix interactions. Human fibroblasts encapsulated in these hydrogels show high viability (>98%) after 7 days of culture. High-resolution confocal microscopy of encapsulated fibroblasts reveals that the cells adopt a more spread morphology in response to higher RGD ligand concentrations and softer gel mechanics. PMID:25111283

Hybrid elastin-like polypeptide-polyethylene glycol (ELP-PEG) hydrogels with improved transparency and independent control of matrix mechanics and cell ligand density.

PubMed

Wang, Huiyuan; Cai, Lei; Paul, Alexandra; Enejder, Annika; Heilshorn, Sarah C

2014-09-08

Hydrogels have been developed as extracellular matrix (ECM) mimics both for therapeutic applications and basic biological studies. In particular, elastin-like polypeptide (ELP) hydrogels, which can be tuned to mimic several biochemical and physical characteristics of native ECM, have been constructed to encapsulate various types of cells to create in vitro mimics of in vivo tissues. However, ELP hydrogels become opaque at body temperature because of ELP's lower critical solution temperature behavior. This opacity obstructs light-based observation of the morphology and behavior of encapsulated cells. In order to improve the transparency of ELP hydrogels for better imaging, we have designed a hybrid ELP-polyethylene glycol (PEG) hydrogel system that rapidly cross-links with tris(hydroxymethyl) phosphine (THP) in aqueous solution via Mannich-type condensation. As expected, addition of the hydrophilic PEG component significantly improves the light transmittance. Coherent anti-Stokes Raman scattering (CARS) microscopy reveals that the hybrid ELP-PEG hydrogels have smaller hydrophobic ELP aggregates at 37 °C. Importantly, this hydrogel platform enables independent tuning of adhesion ligand density and matrix stiffness, which is desirable for studies of cell-matrix interactions. Human fibroblasts encapsulated in these hydrogels show high viability (>98%) after 7 days of culture. High-resolution confocal microscopy of encapsulated fibroblasts reveals that the cells adopt a more spread morphology in response to higher RGD ligand concentrations and softer gel mechanics.

A study of polaritonic transparency in couplers made from excitonic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Mahi R.; Racknor, Chris

2015-03-14

We have studied light matter interaction in quantum dot and exciton-polaritonic coupler hybrid systems. The coupler is made by embedding two slabs of an excitonic material (CdS) into a host excitonic material (ZnO). An ensemble of non-interacting quantum dots is doped in the coupler. The bound exciton polariton states are calculated in the coupler using the transfer matrix method in the presence of the coupling between the external light (photons) and excitons. These bound exciton-polaritons interact with the excitons present in the quantum dots and the coupler is acting as a reservoir. The Schrödinger equation method has been used tomore » calculate the absorption coefficient in quantum dots. It is found that when the distance between two slabs (CdS) is greater than decay length of evanescent waves the absorption spectrum has two peaks and one minimum. The minimum corresponds to a transparent state in the system. However, when the distance between the slabs is smaller than the decay length of evanescent waves, the absorption spectra has three peaks and two transparent states. In other words, one transparent state can be switched to two transparent states when the distance between the two layers is modified. This could be achieved by applying stress and strain fields. It is also found that transparent states can be switched on and off by applying an external control laser field.« less

Graphene, conducting polymer and their composites as transparent and current spreading electrode in GaN solar cells

NASA Astrophysics Data System (ADS)

Mahala, Pramila; Kumar, Ajay; Nayak, Sasmita; Behura, Sanjay; Dhanavantri, Chenna; Jani, Omkar

2016-04-01

Understanding the physics of charge carrier transport at graphene/p-GaN interface is critical for achieving efficient device functionality. Currently, the graphene/p-GaN interface is being explored as light emitting diodes, however this interface can be probed as a potential photovoltaic cell. We report the intimate interfacing of mechanically exfoliated graphene (EG), conducting polymer (PEDOT:PSS) and composite of reduced graphene oxide (rGO) and PEDOT:PSS with a wide band gap p-GaN layer. To explore their potential in energy harvesting, three heterojunction devices such as: (i) EG/p-GaN/sapphire, (ii) PEDOT:PSS/p-GaN/sapphire and (iii) PEDOT:PSS(rGO)/p-GaN/sapphire are designed and their photovoltaic characteristics are examined. It is interesting to observe that the EG/p-GaN/sapphire solar cell exhibits high open-circuit voltage of 0.545 V with low ideality factor and reverse saturation current. However, improved short circuit current density (13.7 mA/cm2) is noticed for PEDOT:PSS/p-GaN/sapphire solar cell because of enhanced conductivity accompanied by high transmittance for PEDOT:PSS. Further, the low series resistance for PEDOT:PSS(rGO)/p-GaN/sapphire is observed suggesting that the PEDOT:PSS and rGO composite is well dispersed and exhibits low interfacial resistances with p-GaN. The present investigation leverages the potential of graphene, conducting polymer and their composites as dual capability of (a) transparent and current spreading electrode and (b) an active top layer to make an intimate contact with wide bandgap p-type GaN for possible prospect towards high performance diodes, switches and solar cells.

One-step synthesis of free-standing α-Ni(OH)2 nanosheets on reduced graphene oxide for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Dong, Bitao; Zhou, Han; Liang, Jin; Zhang, Lusi; Gao, Guoxin; Ding, Shujiang

2014-10-01

In this work, a hierarchical hybrid structure of reduced graphene oxide (rGO) supported ultrathin α-Ni(OH)2 nanosheets (denoted as α-Ni(OH)2@rGO NSs) has been developed successfully via an environmentally friendly one-step solution method. The resulting product of α-Ni(OH)2@rGO NSs was further characterized by scanning electron microscope, transmission electron microscope, x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller. The ultrathin α-Ni(OH)2 nanosheets of around 6 nm in thickness are uprightly coated on the double sides of rGO substrate. When evaluated as electrodes for supercapacitors, the hybrid α-Ni(OH)2@rGO NSs demonstrate excellent supercapacitor performance and cycling stability, compared with the self-aggregated α-Ni(OH)2 powder. Even after 2000 cycles, the hybrid electrodes still can deliver a specific capacitance of 1300 F g-1 at the current density of 5 A g-1, corresponding to no capacity loss of the initial cycle. Such excellent electrochemical performance should be attributed to the ultrathin, free-standing, and hierarchical nanosheets of α-Ni(OH)2, which not only promote efficient charge transport and facilitate the electrolyte diffusion, but also prevent aggregation of electro-active materials effectively during the charge-discharge process.

One-step synthesis of free-standing α-Ni(OH)₂ nanosheets on reduced graphene oxide for high-performance supercapacitors.

PubMed

Dong, Bitao; Zhou, Han; Liang, Jin; Zhang, Lusi; Gao, Guoxin; Ding, Shujiang

2014-10-31

In this work, a hierarchical hybrid structure of reduced graphene oxide (rGO) supported ultrathin α-Ni(OH)2 nanosheets (denoted as α-Ni(OH)2@rGO NSs) has been developed successfully via an environmentally friendly one-step solution method. The resulting product of α-Ni(OH)2@rGO NSs was further characterized by scanning electron microscope, transmission electron microscope, x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller. The ultrathin α-Ni(OH)2 nanosheets of around 6 nm in thickness are uprightly coated on the double sides of rGO substrate. When evaluated as electrodes for supercapacitors, the hybrid α-Ni(OH)2@rGO NSs demonstrate excellent supercapacitor performance and cycling stability, compared with the self-aggregated α-Ni(OH)2 powder. Even after 2000 cycles, the hybrid electrodes still can deliver a specific capacitance of 1300 F g(-1) at the current density of 5 A g(-1), corresponding to no capacity loss of the initial cycle. Such excellent electrochemical performance should be attributed to the ultrathin, free-standing, and hierarchical nanosheets of α-Ni(OH)2, which not only promote efficient charge transport and facilitate the electrolyte diffusion, but also prevent aggregation of electro-active materials effectively during the charge-discharge process.

Predicting the optoelectronic properties of nanowire films based on control of length polydispersity

NASA Astrophysics Data System (ADS)

Large, Matthew J.; Burn, Jake; King, Alice A.; Ogilvie, Sean P.; Jurewicz, Izabela; Dalton, Alan B.

2016-05-01

We demonstrate that the optoelectronic properties of percolating thin films of silver nanowires (AgNWs) are predominantly dependent upon the length distribution of the constituent AgNWs. A generalized expression is derived to describe the dependence of both sheet resistance and optical transmission on this distribution. We experimentally validate the relationship using ultrasonication to controllably vary the length distribution. These results have major implications where nanowire-based films are a desirable material for transparent conductor applications; in particular when application-specific performance criteria must be met. It is of particular interest to have a simple method to generalize the properties of bulk films from an understanding of the base material, as this will speed up the optimisation process. It is anticipated that these results may aid in the adoption of nanowire films in industry, for applications such as touch sensors or photovoltaic electrode structures.

High Refractive Organic–Inorganic Hybrid Films Prepared by Low Water Sol-Gel and UV-Irradiation Processes

PubMed Central

Ma, Hsiao-Yuan; Wang, Tzong-Liu; Chang, Pei-Yu; Yang, Chien-Hsin

2016-01-01

Organic-inorganic hybrid sols (Ti–O–Si precursor) were first synthesized by the sol-gel method at low addition of water, and were then employed to prepare a highly refractive hybrid optical film. This film was obtained by blending the Ti–O–Si precursor with 2-phenylphenoxyethyl acrylate (OPPEA) to perform photo-polymerization by ultraviolet (UV) irradiation. Results show that the film transparency of poly(Ti–O–Si precursor-co-OPPEA) film is higher than that of a pure poly(Ti–O–Si precursor) film, and that this poly(Ti–O–Si precursor-co-OPPEA) hybrid film exhibits a high transparency of ~93.7% coupled with a high refractive index (n) of 1.83 corresponding to a thickness of 2.59 μm. PMID:28344303

Revealing the Double-Edged Sword Role of Graphene on Boosted Charge Transfer versus Active Site Control in TiO2 Nanotube Arrays@RGO/MoS2 Heterostructure.

PubMed

Quan, Quan; Xie, Shunji; Weng, Bo; Wang, Ye; Xu, Yi-Jun

2018-05-01

Charge separation/transfer is generally believed to be the most key factor affecting the efficiency of photocatalysis, which however will be counteracted if not taking the active site engineering into account for a specific photoredox reaction. Here, a 3D heterostructure composite is designed consisting of MoS 2 nanoplatelets decorated on reduced graphene oxide-wrapped TiO 2 nanotube arrays (TNTAs@RGO/MoS 2 ). Such a cascade configuration renders a directional migration of charge carriers and controlled immobilization of active sites, thereby showing much higher photoactivity for water splitting to H 2 than binary TNTAs@RGO and TNTAs/MoS 2 . The photoactivity comparison and mechanistic analysis reveal the double-edged sword role of RGO on boosted charge separation/transfer versus active site control in this composite system. The as-observed inconsistency between boosted charge transfer and lowered photoactivity over TNTAs@RGO is attributed to the decrease of active sites for H 2 evolution, which is significantly different from the previous reports in literature. The findings of the intrinsic relationship of balanced benefits from charge separation/transfer and active site control could promote the rational optimization of photocatalyst design by cooperatively manipulating charge flow and active site control, thereby improving the efficiency of photocatalysis for target photoredox processes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A high-performance, flexible and robust metal nanotrough-embedded transparent conducting film for wearable touch screen panels.

PubMed

Im, Hyeon-Gyun; An, Byeong Wan; Jin, Jungho; Jang, Junho; Park, Young-Geun; Park, Jang-Ung; Bae, Byeong-Soo

2016-02-21

We report a high-performance, flexible and robust metal nanotrough-embedded transparent conducting hybrid film (metal nanotrough-GFRHybrimer). Using an electro-spun polymer nanofiber web as a template and vacuum-deposited gold as a conductor, a junction resistance-free continuous metal nanotrough network is formed. Subsequently, the metal nanotrough is embedded on the surface of a glass-fabric reinforced composite substrate (GFRHybrimer). The monolithic composite structure of our transparent conducting film allows simultaneously high thermal stability (24 h at 250 °C in air), a smooth surface topography (Rrms < 1 nm) and excellent opto-electrical properties. A flexible touch screen panel (TSP) is fabricated using the transparent conducting films. The flexible TSP device stably operates on the back of a human hand and on a wristband.

Graphene—vertically aligned carbon nanotube hybrid on PDMS as stretchable electrodes

NASA Astrophysics Data System (ADS)

Ding, Junjun; Fu, Shichen; Zhang, Runzhi; Boon, Eric; Lee, Woo; Fisher, Frank T.; Yang, Eui-Hyeok

2017-11-01

Stretchable electrodes are a critical component for flexible electronics such as displays, energy devices, and wearable sensors. Carbon nanotubes (CNTs) and graphene have been considered for flexible electrode applications, due to their mechanical strength, high carrier mobility, and excellent thermal conductivity. Vertically aligned carbon nanotubes (VACNTs) provide the possibility to serve as interconnects to graphene sheets as stretchable electrodes that could maintain high electrical conductivity under large tensile strain. In this work, a graphene oxide (GO)-VACNT hybrid on a PDMS substrate was demonstrated. Here, 50 μm long VACNTs were grown on a Si/SiO2 wafer substrate via atmospheric pressure chemical vapor deposition. VACNTs were directly transferred by delamination from the Si/SiO2 to a semi-cured PDMS substrate, ensuring strong adhesion between VACNTs and PDMS upon full curing of the PDMS. GO ink was then printed on the surface of the VACNT carpet and thermally reduced to reduced graphene oxide (rGO). The sheet resistance of the rGO-VACNT hybrid was measured under uniaxial tensile strains up to 300% applied to the substrate. Under applied strain, the rGO-VACNT hybrid maintained a sheet resistant of 386 ± 55 Ω/sq. Cyclic stretching of the rGO-VACNT hybrid was performed with up to 50 cycles at 100% maximum tensile strain, showing no increase in sheet resistance. These results demonstrate promising performance of the rGO-VACNT hybrid for flexible electronics applications.

Graphene-Vertically Aligned Carbon Nanotube Hybrid on PDMS as Stretchable Electrodes.

PubMed

Ding, Junjun; Fu, Shichen; Zhang, Runzhi; Boon, Eric Peter; Lee, Woo; Fisher, Frank T; Yang, Eui-Hyeok

2017-09-11

Stretchable electrodes are a critical component for flexible electronics such as displays, energy devices, and wearable sensors. Carbon nanotubes (CNTs) and graphene have been considered for flexible electrode applications, due to their mechanical strength, high carrier mobility, and excellent thermal conductivity. Vertically aligned carbon nanotubes (VACNTs) provide the possibility to serve as interconnects to graphene sheets as stretchable electrodes that could maintain high electrical conductivity under large tensile strain. In this work, a graphene oxide (GO) -VACNT hybrid on a PDMS substrate was demonstrated. Here, 50 μm long VACNTs were grown on a Si/SiO2 wafer substrate via atmospheric pressure chemical vapor deposition (APCVD). VACNTs were directly transferred by delamination from the Si/SiO2 to a semi-cured PDMS substrate, ensuring strong adhesion between VACNTs and PDMS upon full curing of the PDMS. GO ink was then printed on the surface of the VACNT carpet and thermally reduced to reduced graphene oxide (rGO). The sheet resistance of the rGO-VACNT hybrid was measured under uniaxial tensile strains up to 300% applied to the substrate. Under applied strain, the rGO-VACNT hybrid maintained a sheet resistant of 386±55 Ω/sq. Cyclic stretching of the rGO-VACNT hybrid was performed with up to 50 cycles at 100% maximum tensile strain, showing no increase in sheet resistance. These results demonstrate promising performance of the rGO-VACNT hybrid for flexible electronics applications. © 2017 IOP Publishing Ltd.

Nanoscale α-MnS crystallites grown on N-S co-doped rGO as a long-life and high-capacity anode material of Li-ion batteries

NASA Astrophysics Data System (ADS)

Liu, Boli; Liu, Zhengjiao; Li, Dan; Guo, Pengqian; Liu, Dequan; Shang, Xiaonan; Lv, Mingzhi; He, Deyan

2017-09-01

The rock-salt structural manganous sulfide (α-MnS) is of higher lithium storage capacity. To improve the cyclability of α-MnS anode in lithium-ion batteries, we prepared a composite of α-MnS nanocrystallites grown on nitrogen and sulfur co-doped reduced graphene oxide (rGO) honeycomb framework. N and S atoms have been co-doped into rGO along with the growth of the α-MnS nanocystallites by a one-pot hydrothermal synthesis using thiourea as dopant and reactant. The typical α-MnS/Nsbnd S co-doped rGO (NSG) composite electrode exhibits a reversible capacity as high as 763.5 mAh g-1 after 100 cycles at 100 mA g-1, and a reversible capacity of 576.7 mAh g-1 even after 2000 cycles at 1000 mA g-1. More importantly, the α-MnS/NSG composite electrodes show superior cycle performance at asymmetric discharge/charge current densities. The excellent electrochemical performance can be attributed to that the α-MnS nanocrystallites shorten lithium ion transmission distance, N-S co-doping improves the electronic conductivity of rGO, and the formation of chemical bonds combination between α-MnS and NSG enhances the electrode structural stability and the electron transport. In addition, more stable architecture of NSG-supported ultrafine α-MnS particles is formed upon cycling, which greatly enhances the electrical contact and further improves the electrochemical performance.

High-Performance Wireless Ammonia Gas Sensors Based on Reduced Graphene Oxide and Nano-Silver Ink Hybrid Material Loaded on a Patch Antenna.

PubMed

Wu, Bian; Zhang, Xingfei; Huang, Beiju; Zhao, Yutong; Cheng, Chuantong; Chen, Hongda

2017-09-09

Reduced graphene oxide (rGO) has been studied as a resistive ammonia gas sensor at room temperature. The sensitive hybrid material composed of rGO and nano-silver ink (Ag-ink) was loaded on a microstrip patch antenna to realize high-performance wireless ammonia sensors. The material was investigated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Firstly, interdigital electrodes (IDEs) printed on the polyethylene terephthalate (PET) by direct printing were employed to measure the variation of resistance of the sensitive material with the ammonia concentration. The results indicated the response of sensor varied from 4.25% to 14.7% under 15-200 ppm ammonia concentrations. Furthermore, the hybrid material was loaded on a microstrip patch antenna fabricated by a conventional printed circuit board (PCB) process, and a 10 MHz frequency shift of the sensor antenna could be observed for 200 ppm ammonia gas. Finally, the wireless sensing property of the sensor antenna was successfully tested using the same emitted antenna outside the gas chamber with a high gain of 5.48 dBi, and an increased reflection magnitude of the emitted antenna due to the frequency mismatch of the sensor antenna was observed. Therefore, wireless ammonia gas sensors loaded on a patch antenna have significant application prospects in the field of Internet of Things (IoTs).

High-Performance Wireless Ammonia Gas Sensors Based on Reduced Graphene Oxide and Nano-Silver Ink Hybrid Material Loaded on a Patch Antenna

PubMed Central

Zhang, Xingfei; Huang, Beiju; Zhao, Yutong; Cheng, Chuantong; Chen, Hongda

2017-01-01

Reduced graphene oxide (rGO) has been studied as a resistive ammonia gas sensor at room temperature. The sensitive hybrid material composed of rGO and nano-silver ink (Ag-ink) was loaded on a microstrip patch antenna to realize high-performance wireless ammonia sensors. The material was investigated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Firstly, interdigital electrodes (IDEs) printed on the polyethylene terephthalate (PET) by direct printing were employed to measure the variation of resistance of the sensitive material with the ammonia concentration. The results indicated the response of sensor varied from 4.25% to 14.7% under 15–200 ppm ammonia concentrations. Furthermore, the hybrid material was loaded on a microstrip patch antenna fabricated by a conventional printed circuit board (PCB) process, and a 10 MHz frequency shift of the sensor antenna could be observed for 200 ppm ammonia gas. Finally, the wireless sensing property of the sensor antenna was successfully tested using the same emitted antenna outside the gas chamber with a high gain of 5.48 dBi, and an increased reflection magnitude of the emitted antenna due to the frequency mismatch of the sensor antenna was observed. Therefore, wireless ammonia gas sensors loaded on a patch antenna have significant application prospects in the field of Internet of Things (IoTs). PMID:28891928

Organic-inorganic hybrid optical foils with strong visible reflection, excellent near infrared-shielding ability and high transparency

NASA Astrophysics Data System (ADS)

Zhou, Yijie; Huang, Aibin; Zhou, Huaijuan; Ji, Shidong; Jin, Ping

2018-03-01

Research on functional flexible films has recently been attracting widespread attention especially with regards to foils, which can be designed artificially on the basis of the practical requirements. In this work, a foil with high visible reflection and a strong near infrared shielding efficiency was prepared by a simple wet chemical method. In the process of making this kind of optical foil, emulsion polymerization was first introduced to synthesize polymer opals, which were further compressed between two pieces of polyethylene terephthalate (PET) foil under polymer melting temperature to obtain a photonic crystal film with a strong reflection in the visible region to block blue rays. The following step was to coat a layer of the inorganic nano paint, which was synthesized by dispersing Cs-doped WO3 (CWO) nanoparticles homogenously into organic resin on the surface of the PET to achieve a high near infrared shielding ability. The final composite foil exhibited unique optical properties such as high visible reflectance (23.9%) to block blue rays, and excellent near infrared shielding efficiency (98.0%), meanwhile it still maintained a high transparency meaning that this foil could potentially be applied in energy-saving window films. To sum up, this study provides new insight into devising flexible hybrid films with novel optical properties, which could be further extended to prepare other optical films for potential use in automobile, architectural and other decorative fields.

Transparent lithium-ion batteries

PubMed Central

Yang, Yuan; Jeong, Sangmoo; Hu, Liangbing; Wu, Hui; Lee, Seok Woo; Cui, Yi

2011-01-01

Transparent devices have recently attracted substantial attention. Various applications have been demonstrated, including displays, touch screens, and solar cells; however, transparent batteries, a key component in fully integrated transparent devices, have not yet been reported. As battery electrode materials are not transparent and have to be thick enough to store energy, the traditional approach of using thin films for transparent devices is not suitable. Here we demonstrate a grid-structured electrode to solve this dilemma, which is fabricated by a microfluidics-assisted method. The feature dimension in the electrode is below the resolution limit of human eyes, and, thus, the electrode appears transparent. Moreover, by aligning multiple electrodes together, the amount of energy stored increases readily without sacrificing the transparency. This results in a battery with energy density of 10 Wh/L at a transparency of 60%. The device is also flexible, further broadening their potential applications. The transparent device configuration also allows in situ Raman study of fundamental electrochemical reactions in batteries. PMID:21788483

The art of transparency.

PubMed

Sayim, Bilge; Cavanagh, Patrick

2011-01-01

Artists throughout the ages have discovered a number of techniques to depict transparency. With only a few exceptions, these techniques follow closely the properties of physical transparency. The two best known properties are X-junctions and the luminance relations described by Metelli. X-junctions are seen where the contours of a transparent material cross contours of the surface behind; Metelli's constraints on the luminance relations between the direct and filtered portions of the surface specify a range of luminance values that are consistent with transparency. These principles have been used by artists since the time of ancient Egypt. However, artists also discovered that stimuli can be seen as transparent even when these physical constraints are not met. Ancient Greek artists, for example, were able to depict transparent materials in simple black-and-white line drawings. Artists also learned how to represent transparency in cases where neither X-junctions nor Metelli's constraints could apply: for example, where no portions of the objects behind the transparent material extend beyond it. Many painters convincingly portrayed transparency in these cases by depicting the effects the transparent medium would have on material or object properties. Here, we show how artists employed these and other techniques revealing their anticipation of current formalizations of perceived transparency, and we suggest new, as-yet-untested principles.

The art of transparency

PubMed Central

Sayim, Bilge; Cavanagh, Patrick

2011-01-01

Artists throughout the ages have discovered a number of techniques to depict transparency. With only a few exceptions, these techniques follow closely the properties of physical transparency. The two best known properties are X-junctions and the luminance relations described by Metelli. X-junctions are seen where the contours of a transparent material cross contours of the surface behind; Metelli's constraints on the luminance relations between the direct and filtered portions of the surface specify a range of luminance values that are consistent with transparency. These principles have been used by artists since the time of ancient Egypt. However, artists also discovered that stimuli can be seen as transparent even when these physical constraints are not met. Ancient Greek artists, for example, were able to depict transparent materials in simple black-and-white line drawings. Artists also learned how to represent transparency in cases where neither X-junctions nor Metelli's constraints could apply: for example, where no portions of the objects behind the transparent material extend beyond it. Many painters convincingly portrayed transparency in these cases by depicting the effects the transparent medium would have on material or object properties. Here, we show how artists employed these and other techniques revealing their anticipation of current formalizations of perceived transparency, and we suggest new, as-yet-untested principles. PMID:23145252

Pyrene-Functionalized PTMA by NRC for Greater π-π Stacking with rGO and Enhanced Electrochemical Properties.

PubMed

Zhang, Kai; Hu, Yuxiang; Wang, Lianzhou; Monteiro, Michael J; Jia, Zhongfan

2017-10-11

Nitroxide radical polymers can undergo both excellent electrochemical redox reactions and a rapid "click" coupling reaction with carbon-centered radicals (i.e., nitroxide radical coupling (NRC) reaction). In this work, we report a strategy to functionalize poly(2,2,6,6,-tetramethylpiperidinyl-1-oxyl methacrylate) (PTMA) with pyrene side groups through a rapid and near quantitative NRC reaction. This resulted in P(TMA-co-PyMA) random copolymers with near quantitative amounts of pyrene along the PTMA chain for greater π-π interaction with rGO, while the nitroxide radicals on the polymer could simultaneously be used for energy storage. These copolymers can bind with reduced graphene oxide (rGO) and form layered composites through noncovalent π-π stacking, attaining molecular-level dispersion. Electrochemical performance of the composites with different polymer contents (24, 35, and 45 wt %), tested in lithium ion batteries, indicated that the layered structures consisting of P(TMA-co-PyMA) maintained greater capacities at high C-rates. This simple and efficient strategy to synthesize pyrene-functionalized polymers will provide new opportunities to fabricate many other polymer composite electrodes for desired electrochemical performance.

Designing of Hybrid Structured Glass Laminated Transparent Nano Composites through Vacuum infusion Technique

NASA Astrophysics Data System (ADS)

Mukherji, A.; Tarapure, N. D.; Wakure, G. N.

2017-05-01

Glass is the most commonly used transparent material. However, glass is not suitable in applications where low weight, high strength is required. The present invention comprises a method of making a Transparent Glass Laminated Nano composite product. The product contains a Bidirectionally oriented E-Glass Fabric an essentially bidirectional yarn woven fabrics is stretched Bidirectionally by specially fabricated steel frame associated with both co and counter rotating device. These fibers include glass fibrics/cloths or mixtures of any of these. The synthetic fiber may be any synthetic silica based oven waived bi-directional or Uni-directional fabrics. Engaged gear provided in the device develops uniform tension on fabric, in both direction. Nano particle dispersed resin to be used is formulated with their respective curing agents and extenders. The formulated resin contains 0.1-0.5% of Nano additives and the product composed from 5-10 % of Glass fabric, between 10 to 20 % of ordinary glass, and between 60-80 % of the product is the Nano particles dispersed formulated resin, all measured by volume.

Handedness Dependent Electromagnetically Induced Transparency in Hybrid Chiral Metamaterials

NASA Astrophysics Data System (ADS)

Kang, Lei; Hao Jiang, Zhi; Yue, Taiwei; Werner, Douglas H.

2015-07-01

We provide the first experimental demonstration of the handedness dependent electromagnetically induced transparency (EIT) in chiral metamaterials during the interaction with circularly polarized waves. The observed chiral-sensitive EIT phenomena arise from the coherent excitation of a non-radiative mode in the component split ring resonators (SRRs) produced by the corresponding Born-Kuhn type (radiative) resonators that are responsible for the pronounced chirality. The coherent coupling, which is dominated by the bonding and antibonding resonances of the Born-Kuhn type resonators, leads to an extremely steep dispersion for a circularly polarized wave of predefined handedness. Accordingly, retrieved effective medium parameters from simulated results further reveal a difference of 80 in the group indices for left- and right-handed circularly polarized waves at frequencies within the EIT window, which can potentially result in handedness-sensitive pulse delays. These chiral metamaterials which enable a handedness dependent EIT effect may provide more degrees of freedom for designing circular polarization based communication devices.

Hybrid plasmonic systems: from optical transparencies to strong coupling and entanglement

NASA Astrophysics Data System (ADS)

Gray, Stephen K.

2018-02-01

Classical electrodynamics and quantum mechanical models of quantum dots and molecules interacting with plasmonic systems are discussed. Calculations show that just one quantum dot interacting with a plasmonic system can lead to interesting optical effects, including optical transparencies and more general Fano resonance features that can be tailored with ultrafast laser pulses. Such effects can occur in the limit of moderate coupling between quantum dot and plasmonic system. The approach to the strong coupling regime is also discussed. In cases with two or more quantum dots within a plasmonic system, the possibility of quantum entanglement mediated through the dissipative plasmonic structure arises.

Photo-reduction of bromate in drinking water by metallic Ag and reduced graphene oxide (RGO) jointly modified BiVO4 under visible light irradiation.

PubMed

Chen, Fei; Yang, Qi; Zhong, Yu; An, Hongxue; Zhao, Jianwei; Xie, Ting; Xu, Qiuxiang; Li, Xiaoming; Wang, Dongbo; Zeng, Guangming

2016-09-15

Bromate (BrO3(-)), an oxyhalide disinfection by-product (DBP) in drinking water, has been demonstrated to be carcinogenic and genotoxic. In the current work, metallic Ag and reduced graphene oxide (RGO) co-modified BiVO4 was successfully synthesized by a stepwise chemical method coupling with a photo-deposition process and applied in the photo-reduction of BrO3(-) under visible light irradiation. In this composite, metallic Ag acted as an electron donor or mediator and RGO enhanced the BrO3(-) adsorption onto the surface of catalysts as well as an electron acceptor to restrict the recombination of photo-generated electron-hole pairs. The Ag@BiVO4@RGO composite exhibited greater photo-reduction BrO3(-) performance than pure BiVO4, Ag@BiVO4 and RGO@BiVO4 under identical experimental conditions: initial BrO3(-) concentration 150 μg/L, catalyst dosage 0.5 g/L, pH 7.0 and visible light (λ > 420 nm). The photoluminescence spectra (PL), electron-spin resonance (ESR), photocurrent density (PC) and electrochemical impedance spectroscopy (EIS) measurements indicated that the modified BiVO4 enhanced the photo-generated electrons and separated the electron-hole pairs. The photocatalytic reduction efficiency for BrO3(-) removal decreased with the addition of electron quencher K2S2O8, suggesting that electrons were the primary factor in this photo-reduction process. The declining photo-reduction efficiency of BrO3(-) in tap water should attribute to the consumption of photo-generated electrons by coexisting anions and the adsorption of dissolved organic matter (DOM) on graphene surface. The overall results indicate a promising application potential for photo-reduction in the DBPs removal from drinking water. Copyright © 2016 Elsevier Ltd. All rights reserved.

Plasmonic transparent conductors

NASA Astrophysics Data System (ADS)

Liapis, Andreas C.; Sfeir, Matthew Y.; Black, Charles T.

2016-09-01

Many of today's technological applications, such as solar cells, light-emitting diodes, displays, and touch screens, require materials that are simultaneously optically transparent and electrically conducting. Here we explore transparent conductors based on the excitation of surface plasmons in nanostructured metal films. We measure both the optical and electrical properties of films perforated with nanometer-scale features and optimize the design parameters in order to maximize optical transmission without sacrificing electrical conductivity. We demonstrate that plasmonic transparent conductors can out-perform indium tin oxide in terms of both their transparency and their conductivity.

Electromagnetically induced transparency control in terahertz metasurfaces based on bright-bright mode coupling

NASA Astrophysics Data System (ADS)

Yahiaoui, R.; Burrow, J. A.; Mekonen, S. M.; Sarangan, A.; Mathews, J.; Agha, I.; Searles, T. A.

2018-04-01

We demonstrate a classical analog of electromagnetically induced transparency (EIT) in a highly flexible planar terahertz metamaterial (MM) comprised of three-gap split-ring resonators. The keys to achieve EIT in this system are the frequency detuning and hybridization processes between two bright modes coexisting in the same unit cell as opposed to bright-dark modes. We present experimental verification of two bright modes coupling for a terahertz EIT-MM in the context of numerical results and theoretical analysis based on a coupled Lorentz oscillator model. In addition, a hybrid variation of the EIT-MM is proposed and implemented numerically to dynamically tune the EIT window by incorporating photosensitive silicon pads in the split gap region of the resonators. As a result, this hybrid MM enables the active optical control of a transition from the on state (EIT mode) to the off state (dipole mode).

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

PubMed Central

Scheer, Elke; Polarz, Sebastian

2017-01-01

Single layer graphite, known as graphene, is an important material because of its unique two-dimensional structure, high conductivity, excellent electron mobility and high surface area. To explore the more prospective properties of graphene, graphene hybrids have been synthesised, where graphene has been integrated with other important nanoparticles (NPs). These graphene–NP hybrid structures are particularly interesting because after hybridisation they not only display the individual properties of graphene and the NPs, but also they exhibit further synergistic properties. Reduced graphene oxide (rGO), a graphene-like material, can be easily prepared by reduction of graphene oxide (GO) and therefore offers the possibility to fabricate a large variety of graphene–transition metal oxide (TMO) NP hybrids. These hybrid materials are promising alternatives to reduce the drawbacks of using only TMO NPs in various applications, such as anode materials in lithium ion batteries (LIBs), sensors, photocatalysts, removal of organic pollutants, etc. Recent studies have shown that a single graphene sheet (GS) has extraordinary electronic transport properties. One possible route to connecting those properties for application in electronics would be to prepare graphene-wrapped TMO NPs. In this critical review, we discuss the development of graphene–TMO hybrids with the detailed account of their synthesis. In addition, attention is given to the wide range of applications. This review covers the details of graphene–TMO hybrid materials and ends with a summary where an outlook on future perspectives to improve the properties of the hybrid materials in view of applications are outlined. PMID:28462071

Soils. Transparency Masters.

ERIC Educational Resources Information Center

Clemson Univ., SC. Vocational Education Media Center.

This document is a collection of 43 overhead transparency masters to be used as teaching aids in a course of study involving soils such as geology, agronomy, hydrology, earth science, or land use study. Some transparencies are in color. Selected titles of transparencies may give the reader a better understanding of the graphic content. Titles are:…

Photocatalytic activity of TiO2/Nb2O5/PANI and TiO2/Nb2O5/RGO as new nanocomposites for degradation of organic pollutants.

PubMed

Zarrin, Saviz; Heshmatpour, Felora

2018-06-05

In this study, highly active titanium dioxide modified by niobium oxide (Nb 2 O 5 ), polymer (PANI) and reduced graphene oxide (RGO) were successfully prepared. The morphology, structure, surface area and light absorption properties of the present nanocomposites for removal of methylene blue (MB) and methyl orange (MO) were investigated and compared with those of TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. The characterization techniques such as XRD, FT-IR, UV-vis, SEM, EDX, BET and TEM were employed in order to identify the nanocomposites. Also, photocatalytic properties of TiO 2 /Nb 2 O 5 /PANI and TiO 2 /Nb 2 O 5 /RGO nanocomposites under visible light irradiation were studied. In this way, the obtained results were compared to each other and also compared to TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. In this context, the chemical oxygen demand (COD) removal follows the photodegradation in observed performance. The results indicate that reduced TiO 2 /Nb 2 O 5 nanocomposite is effectively modified by graphene oxide to give TiO 2 /Nb 2 O 5 /RGO composite. The TiO 2 /Nb 2 O 5 /RGO exhibits significantly higher photocatalytic activity in degradation of organic dyes under visible light rather than that of TiO 2 /Nb 2 O 5 /PANI, TiO 2 /Nb 2 O 5 and pure TiO 2 . Copyright © 2018 Elsevier B.V. All rights reserved.

Design and Characterization of a Gradient-Transparent RF Copper Shield for PET Detector Modules in Hybrid MR-PET Imaging

NASA Astrophysics Data System (ADS)

Berneking, Arne; Trinchero, Riccardo; Ha, YongHyun; Finster, Felix; Cerello, Piergiorgio; Lerche, Christoph; Shah, Nadim Jon

2017-05-01

This paper focuses on the design and the characterization of a frequency-selective shield for positron emission tomography (PET) detector modules of hybrid magnetic resonance-PET scanners, where the shielding of the PET cassettes is located close to the observed object. The proposed shielding configuration is designed and optimized to guarantee a high shielding effectiveness (SE) of up to 60 dB for B1-fields at the Larmor frequency of 64 MHz, thus preventing interactions between the radio-frequency (RF) coil and PET electronics. On the other hand, the shield is transparent to the gradient fields with the consequence that eddy-current artifacts in the acquired EPI images are significantly reduced with respect to the standard solid-shield configuration. The frequency-selective behavior of the shield is characterized and validated via simulation studies with CST MICROWAVE STUDIO in the megahertz and kilohertz range. Bench measurements with an RF coil built in-house demonstrated the high SE at the Larmor frequency. Moreover, measurements on a 4-T human scanner confirmed the abolishment of eddy current artifact and also provided an understanding of where the eddy currents occur with respect to the sequence parameters. Simulations and measurements for the proposed shielding concept were compared with a solid copper shielding configuration.

Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction

NASA Astrophysics Data System (ADS)

Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P.; Lee, Jihun; Yang, Junghee; Lee, Hyoyoung

2015-09-01

The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm-1 (at 0 % strain) and 322.8 S cm-1 (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles.

Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction.

PubMed

Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P; Lee, JiHun; Yang, Junghee; Lee, Hyoyoung

2015-09-18

The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm(-1) (at 0 % strain) and 322.8 S cm(-1) (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles.

A flexible and transparent graphene/ZnO nanorod hybrid structure fabricated by exfoliating a graphite substrate

NASA Astrophysics Data System (ADS)

Nam, Gwang-Hee; Baek, Seong-Ho; Cho, Chang-Hee; Park, Il-Kyu

2014-09-01

We demonstrate the fabrication of a graphene/ZnO nanorod (NR) hybrid structure by mechanical exfoliation of ZnO NRs grown on a graphite substrate. We confirmed the existence of graphene sheets on the hybrid structure by analyzing the Raman spectra and current-voltage (I-V) characteristics. The Raman spectra of the exfoliated graphene/ZnO NR hybrid structure show G and 2D band peaks that are shifted to lower wavenumbers, indicating that the exfoliated graphene layer exists under a significant amount of strain. The I-V characteristics of the graphene/ZnO NR hybrid structure show current flow through the graphene layer, while no current flow is observed on the ZnO NR/polydimethylsiloxane (PDMS) composite without graphene, thereby indicating that the few-layer graphene was successfully transferred onto the hybrid structure. A piezoelectric nanogenerator is demonstrated by using the fabricated graphene/ZnO NR hybrid structure. The nanogenerator exhibits stable output voltage up to 3.04 V with alternating current output characteristics.We demonstrate the fabrication of a graphene/ZnO nanorod (NR) hybrid structure by mechanical exfoliation of ZnO NRs grown on a graphite substrate. We confirmed the existence of graphene sheets on the hybrid structure by analyzing the Raman spectra and current-voltage (I-V) characteristics. The Raman spectra of the exfoliated graphene/ZnO NR hybrid structure show G and 2D band peaks that are shifted to lower wavenumbers, indicating that the exfoliated graphene layer exists under a significant amount of strain. The I-V characteristics of the graphene/ZnO NR hybrid structure show current flow through the graphene layer, while no current flow is observed on the ZnO NR/polydimethylsiloxane (PDMS) composite without graphene, thereby indicating that the few-layer graphene was successfully transferred onto the hybrid structure. A piezoelectric nanogenerator is demonstrated by using the fabricated graphene/ZnO NR hybrid structure. The nanogenerator

Cu mesh for flexible transparent conductive electrodes.

PubMed

Kim, Won-Kyung; Lee, Seunghun; Hee Lee, Duck; Hee Park, In; Seong Bae, Jong; Woo Lee, Tae; Kim, Ji-Young; Hun Park, Ji; Chan Cho, Yong; Ryong Cho, Chae; Jeong, Se-Young

2015-06-03

Copper electrodes with a micromesh/nanomesh structure were fabricated on a polyimide substrate using UV lithography and wet etching to produce flexible transparent conducting electrodes (TCEs). Well-defined mesh electrodes were realized through the use of high-quality Cu thin films. The films were fabricated using radio-frequency (RF) sputtering with a single-crystal Cu target--a simple but innovative approach that overcame the low oxidation resistance of ordinary Cu. Hybrid Cu mesh electrodes were fabricated by adding a capping layer of either ZnO or Al-doped ZnO. The sheet resistance and the transmittance of the electrode with an Al-doped ZnO capping layer were 6.197 ohm/sq and 90.657%, respectively, and the figure of merit was 60.502 × 10(-3)/ohm, which remained relatively unchanged after thermal annealing at 200 °C and 1,000 cycles of bending. This fabrication technique enables the mass production of large-area flexible TCEs, and the stability and high performance of Cu mesh hybrid electrodes in harsh environments suggests they have strong potential for application in smart displays and solar cells.

Nitrogen Dioxide-Sensing Properties at Room Temperature of Metal Oxide-Modified Graphene Composite via One-Step Hydrothermal Method

NASA Astrophysics Data System (ADS)

Zhang, Dongzhi; Liu, Jingjing; Xia, Bokai

2016-08-01

A metal oxide/graphene composite film-based sensor toward room-temperature detection of ppm-level nitrogen dioxide (NO2) gas has been demonstrated. The sensor prototype was constructed on a PCB substrate with microelectrodes, and a tin oxide-reduced graphene oxide (SnO2-rGO) composite as sensing film was prepared by one-step hydrothermal synthesis of tin tetrachloride pentahydrate solution in the presence of graphene oxide (GO). The SnO2-rGO hybrid composite was examined by scanning electron microscope and x-ray diffraction (XRD). The gas sensing properties of the SnO2-rGO composite were investigated at room temperature by exposing it to a wide concentration ranging from 1 ppm to 2000 ppm toward NO2 gas. The experiment results showed that the sensor exhibited a high response, superior selectivity, good repeatability, rapid response/recovery characteristics and low detection limit of 1 ppm, which exceeded that of a pure rGO sensor. The gas sensing mechanisms of the proposed sensor toward NO2 were possibly attributed to the nano-hybrid structures and n- p heterojunctions created at the interface of the SnO2 nanocrystals and rGO nanosheets.

Layer-by-Layer-Assembled AuNPs-Decorated First-Generation Poly(amidoamine) Dendrimer with Reduced Graphene Oxide Core as Highly Sensitive Biosensing Platform with Controllable 3D Nanoarchitecture for Rapid Voltammetric Analysis of Ultratrace DNA Hybridization.

PubMed

Jayakumar, Kumarasamy; Camarada, María Belén; Dharuman, Venkataraman; Rajesh, Rajendiran; Venkatesan, Rengarajan; Ju, Huangxian; Maniraj, Mahalingam; Rai, Abhishek; Barman, Sudipta Roy; Wen, Yangping

2018-06-27

The structure and electrochemical properties of layer-by-layer-assembled gold nanoparticles (AuNPs)-decorated first-generation (G1) poly(amidoamine) dendrimer (PD) with reduced graphene oxide (rGO) core as a highly sensitive and label-free biosensing platform with a controllable three-dimensional (3D) nanoarchitecture for the rapid voltammetric analysis of DNA hybridization at ultratrace levels were characterized. Mercaptopropinoic acid (MPA) was self-assembled onto Au substrate, then GG1PD formed by the covalent functionalization between the amino terminals of G1PD and carboxyl terminals of rGO was covalently linked onto MPA, and finally AuNPs were decorated onto GG1PD by strong physicochemical interaction between AuNPs and -OH of rGO in GG1PD, which was characterized through different techniques and confirmed by computational calculation. This 3D controllable thin-film electrode was optimized and evaluated using [Fe(CN) 6 ] 3-/4- as the redox probe and employed to covalently immobilize thiol-functionalized single-stranded DNA as biorecognition element to form the DNA nanobiosensor, which achieved fast, ultrasensitive, and high-selective differential pulse voltammetric analysis of DNA hybridization in a linear range from 1 × 10 -6 to 1 × 10 -13 g m -1 with a low detection limit of 9.07 × 10 -14 g m -1 . This work will open a new pathway for the controllable 3D nanoarchitecture of the layer-by-layer-assembled metal nanoparticles-functionalized lower-generation PD with two-dimensional layered nanomaterials as cores that can be employed as ultrasensitive and label-free nanobiodevices for the fast diagnosis of specific genome diseases in the field of biomedicine.

Transparent 'solution' of ultrathin magnesium hydroxide nanocrystals for flexible and transparent nanocomposite films.

PubMed

Wang, Jie-Xin; Sun, Qian; Chen, Bo; Wu, Xi; Zeng, Xiao-Fei; Zhang, Cong; Zou, Hai-Kui; Chen, Jian-Feng

2015-05-15

Transparent solutions of nanocrystals exhibit many unique properties, and are thus attractive materials for numerous applications. However, the synthesis of transparent nanocrystal solutions of magnesium hydroxide (MH) with wide applications is yet to be realized. Here, we report a facile two-step process, which includes a direct reactive precipitation in alcohol phase instead of aqueous phase combined with a successive surface modification, to prepare transparent alcohol solutions containing lamellar MH nanocrystals with an average size of 52 nm and an ultrathin thickness of 1-2 nm, which is the thinnest MH nanoplatelet reported in the literatures. Further, highly flexible and transparent nanocomposite films are fabricated with a solution mixing method by adding the transparent MH nanocrystal solutions into PVB solution. Considering the simplicity of the fabrication process, high transparency and good flexibility, this MH/polymer nanocomposite film is promising for flame-resistant applications in plastic electronics and optical devices with high transparency, such as flexible displays, optical filters, and flexible solar cells.

Graphene/Ruthenium Active Species Aerogel as Electrode for Supercapacitor Applications

PubMed Central

Gigot, Arnaud; Fontana, Marco; Pirri, Candido Fabrizio; Rivolo, Paola

2017-01-01

Ruthenium active species containing Ruthenium Sulphide (RuS2) is synthesized together with a self-assembled reduced graphene oxide (RGO) aerogel by a one-pot hydrothermal synthesis. Ruthenium Chloride and L-Cysteine are used as reactants. The hydrothermal synthesis of the innovative hybrid material occurs at 180 °C for 12 h, by using water as solvent. The structure and morphology of the hybrid material are fully characterized by Raman, XRD, XPS, FESEM and TEM. The XRD and diffraction pattern obtained by TEM display an amorphous nanostructure of RuS2 on RGO crystallized flakes. The specific capacitance measured in planar configuration in 1 M NaCl electrolyte at 5 mV s−1 is 238 F g−1. This supercapacitor electrode also exhibits perfect cyclic stability without loss of the specific capacitance after 15,000 cycles. In summary, the RGO/Ruthenium active species hybrid material demonstrates remarkable properties for use as active material for supercapacitor applications. PMID:29301192

Graphene/Ruthenium Active Species Aerogel as Electrode for Supercapacitor Applications.

PubMed

Gigot, Arnaud; Fontana, Marco; Pirri, Candido Fabrizio; Rivolo, Paola

2017-12-30

Ruthenium active species containing Ruthenium Sulphide (RuS₂) is synthesized together with a self-assembled reduced graphene oxide (RGO) aerogel by a one-pot hydrothermal synthesis. Ruthenium Chloride and L-Cysteine are used as reactants. The hydrothermal synthesis of the innovative hybrid material occurs at 180 °C for 12 h, by using water as solvent. The structure and morphology of the hybrid material are fully characterized by Raman, XRD, XPS, FESEM and TEM. The XRD and diffraction pattern obtained by TEM display an amorphous nanostructure of RuS₂ on RGO crystallized flakes. The specific capacitance measured in planar configuration in 1 M NaCl electrolyte at 5 mV s -1 is 238 F g -1 . This supercapacitor electrode also exhibits perfect cyclic stability without loss of the specific capacitance after 15,000 cycles. In summary, the RGO/Ruthenium active species hybrid material demonstrates remarkable properties for use as active material for supercapacitor applications.

Note: Hybrid active/passive force feedback actuator using hydrostatic transmission.

PubMed

Park, Yea-Seok; Lee, Juwon; Kim, Kyung-Soo; Kim, Soohyun

2017-12-01

A hybrid actuator for haptic devices is proposed in this paper. The actuator is composed of a DC motor and a magneto-rheological (MR) brake to realize transparency and stable force control. Two piston cylinders are connected with a flexible tube to lighten the weight of the structures on the endpoint that interacts with an operator. Also, the MR brake is designed to be suitable for hydraulic transmission. For the proposed hybrid actuator, a cooperative force control method using a pressure sensor instead of a force sensor is proposed. To verify the proposed control algorithm, a virtual wall collision experiment was conducted using a developed prototype of the hybrid actuator.

Note: Hybrid active/passive force feedback actuator using hydrostatic transmission

NASA Astrophysics Data System (ADS)

Park, Yea-Seok; Lee, Juwon; Kim, Kyung-Soo; Kim, Soohyun

2017-12-01

A hybrid actuator for haptic devices is proposed in this paper. The actuator is composed of a DC motor and a magneto-rheological (MR) brake to realize transparency and stable force control. Two piston cylinders are connected with a flexible tube to lighten the weight of the structures on the endpoint that interacts with an operator. Also, the MR brake is designed to be suitable for hydraulic transmission. For the proposed hybrid actuator, a cooperative force control method using a pressure sensor instead of a force sensor is proposed. To verify the proposed control algorithm, a virtual wall collision experiment was conducted using a developed prototype of the hybrid actuator.

A flexible and transparent graphene/ZnO nanorod hybrid structure fabricated by exfoliating a graphite substrate.

PubMed

Nam, Gwang-Hee; Baek, Seong-Ho; Cho, Chang-Hee; Park, Il-Kyu

2014-10-21

We demonstrate the fabrication of a graphene/ZnO nanorod (NR) hybrid structure by mechanical exfoliation of ZnO NRs grown on a graphite substrate. We confirmed the existence of graphene sheets on the hybrid structure by analyzing the Raman spectra and current-voltage (I-V) characteristics. The Raman spectra of the exfoliated graphene/ZnO NR hybrid structure show G and 2D band peaks that are shifted to lower wavenumbers, indicating that the exfoliated graphene layer exists under a significant amount of strain. The I-V characteristics of the graphene/ZnO NR hybrid structure show current flow through the graphene layer, while no current flow is observed on the ZnO NR/polydimethylsiloxane (PDMS) composite without graphene, thereby indicating that the few-layer graphene was successfully transferred onto the hybrid structure. A piezoelectric nanogenerator is demonstrated by using the fabricated graphene/ZnO NR hybrid structure. The nanogenerator exhibits stable output voltage up to 3.04 V with alternating current output characteristics.

Synthesis and characterization of Mn-ZnFe2O4 and Mn-ZnFe2O4/rGO nanocomposites from waste batteries for photocatalytic, electrochemical and thermal studies

NASA Astrophysics Data System (ADS)

Mylarappa, M.; Venkata Lakshmi, V.; Vishnu Mahesh, K. R.; Nagaswarupa, H. P.; Raghavendra, N.

2017-11-01

In the present paper, Mn-ZnFe2O4 and Mn-ZnFe2O4/rGO composites recovered from waste batteries using acid dissolution and ferrite processing were studied. The recovered Mn-ZnFe2O4 nanocomposites were decorated onto rGO using the facile hydrothermal method. The recovered material was characterized using x-ray powder diffraction to study the particle size and crystallinity. The morphology of the composites was analyzed using scanning electron microscopy, and elements present in the materials were studied using energy dispersive x-ray analysis. The functional groups attached were observed using a Fourier transform infrared spectrometer. Furthermore, the recovered composites were evaluated in thermal studies using thermal gravimetric analysis, differential scanning calorimetry and dynamic thermal analysis. The material was used as a photocatalyst for the removal of acid orange 88 dye, and as an electrocatalyst. The decreased band gap energy for the Mn-ZnFe2O4/rGO composite was displayed in better photocatalytic activity for a given reaction. The electrochemical properties of Mn-ZnFe2O4 and Mn-ZnFe2O4/rGO have been investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) with a paste-type electrode. The CV indicated the reversibility of the electrode reaction, and the EIS revealed that a decrease in the charge transfer resistance increases the double layer capacitance of the rGO/Mn-ZnFe2O4 electrode.

Integrated graphene/nanoparticle hybrids for biological and electronic applications

NASA Astrophysics Data System (ADS)

Nguyen, Kim Truc; Zhao, Yanli

2014-05-01

The development of novel graphene/nanoparticle hybrid materials is currently the subject of tremendous research interest. The intrinsic exceptional assets of both graphene (including graphene oxide and reduced graphene oxide) and nanoparticles render their hybrid materials synergic properties that can be useful in various applications. In this feature review, we highlight recent developments in graphene/nanoparticle hybrids and their promising potential in electronic and biological applications. First, the latest advances in synthetic methods for the preparation of the graphene/nanoparticle hybrids are introduced, with the emphasis on approaches to (1) decorate nanoparticles onto two-dimensional graphene and (2) wrap nanoparticles with graphene sheets. The pros and cons of large-scale synthesis are also discussed. Then, the state-of-the-art of graphene/nanoparticle hybrids in electronic and biological applications is reviewed. For electronic applications, we focus on the advantages of using these hybrids in transparent conducting films, as well as energy harvesting and storage. Biological applications, electrochemical biosensing, bioimaging, and drug delivery using the hybrids are showcased. Finally, the future research prospects and challenges in this rapidly developing area are discussed.

A solution-doped small molecule hole transport layer for efficient ITO-free organic solar cells (Presentation Recording)

NASA Astrophysics Data System (ADS)

Bormann, Ludwig; Selzer, Franz; Leo, Karl; Mueller-Meskamp, Lars

2015-10-01

Indium-tin-oxide-free (ITO-free) organic solar cells are an important, emerging research field because ITO transparent electrodes are a bottleneck for cheap large area devices on flexible substrates. Among highly conductive PEDOT:PSS and metal grids, percolation networks made of silver nanowires (AgNW) with a diameter in the nanoscale show a huge potential due to easy processing (e.g. spray coating), high aspect ratios and excellent electrical and optical properties like 15 Ohm/sq with a transmission of 83.5 % including the substrate. However, the inherent surface roughness of the AgNW film impedes the implementation as bottom electrode in organic devices, especially fully vacuum deposited ones, where often shunts are obtained. Here, we report about the solution processing of a small molecule hole transport layer (s-HTL) comprising N,N'-((Diphenyl-N,N'-bis)9,9,-dimethyl-fluoren-2-yl)-benzidine (BF-DPB, host material) and the proprietary NDP9 (p-dopant) deposited from tetrahydrofuran (THF) as non-halogenated, "green" solvent. We show, that the doping process already takes place in solution and that conductivities, achieved with this process at high doping efficiencies (4 * 10^-4 S/cm at 10 wt% doping concentration), are comparable to thermal co-evaporation of BF-DPB:NDP9 under high vacuum, which is the proven deposition method for doped small molecule films. Applying this s-HTL to AgNW films leads to well smoothened electrodes, ready for application in organic devices. Vacuum-deposited organic p-i-n solar cells with DCV2-5T-Me(3:3):C60 as active layer show a power conversion efficiency of 4.4% and 3.7% on AgNW electrode with 35nm and 90 nm wire diameter, compared to 4.1% on ITO with the s-HTL.

Semitransparent inverted organic solar cell with improved absorption and reasonable transparency perception based on the nanopatterned MoO3/Ag/MoO3 anode

NASA Astrophysics Data System (ADS)

Tian, Ximin; Zhang, Ye; Hao, Yuying; Cui, Yanxia; Wang, Wenyan; Shi, Fang; Wang, Hua; Wei, Bin; Huang, Wei

2015-01-01

We demonstrate an inverted low bandgap semitransparent organic solar cell with improved absorption as well as reasonable transparency perception based on a nanopatterned MoO3/Ag/MoO3 (MAM) multilayer film as the transparent anode under illumination from the MAM side. The integrated absorption efficiency of the active layer at normal hybrid-polarized incidence considering an AM 1.5G solar spectrum is up to 51.69%, increased by 18.53% as compared to that of the equivalent planar device (43.61%) and reaching 77.3% of that of the corresponding opaque nanopatterned device (66.90%). Detailed investigations reveal that the excitation of plasmonic waveguide modes (at transverse magnetic polarization) and photonic modes (at transverse electric polarization) are responsible for the observed enhancement in absorption. Importantly, the proposed device exhibits an average transmittance of up to 28.4% and an average transparency perception of 26.3% for the human eyes under hybrid-polarized light illumination along with a good color rendering property. Additionally, our proposal works very well over a fairly wide angular range.

Magnetic Fe3O4@V2O5/rGO nanocomposite as a recyclable photocatalyst for dye molecules degradation under direct sunlight irradiation.

PubMed

Boruah, Purna K; Szunerits, Sabine; Boukherroub, Rabah; Das, Manash R

2018-01-01

Reduced graphene oxide nanosheets decorated with Fe 3 O 4 and V 2 O 5 nanoparticles as a magnetically recoverable nanocomposite (Fe 3 O 4 @V 2 O 5 /rGO) was synthesized by a simple solution chemistry approach. The synthesized nanocomposite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), Fourier transform infrared (FTIR), fluorescence, and zeta potential measurements. The narrow band gap and different band gap energies of Fe 3 O 4 and V 2 O 5 proved to be suitable for the absorption of visible light in the solar spectrum. The Fe 3 O 4 @V 2 O 5 /rGO displayed indeed excellent photocatalytic activity towards the degradation of harmful cationic Bismarck Brown (BB) as well as anionic Acid Orange 7 (AO) dyes under direct sunlight irradiation. The photocatalytic activity of the Fe 3 O 4 @V 2 O 5 /rGO is influenced by solution pH, catalyst loading, initial dye concentration and the presence of different inorganic ions (NH 4 + , Na + , Mg 2+ , Ca 2+, SO 4 2- , Br - , NO 3 - , Cl - , HCO 3 - ). This study provides a new scientific knowledge on the sunlight driven photocatalytic degradation of dye molecules using novel mixed metal oxide/rGO nanocomposite photocatalyst. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fabrication of fully transparent nanowire transistors for transparent and flexible electronics

NASA Astrophysics Data System (ADS)

Ju, Sanghyun; Facchetti, Antonio; Xuan, Yi; Liu, Jun; Ishikawa, Fumiaki; Ye, Peide; Zhou, Chongwu; Marks, Tobin J.; Janes, David B.

2007-06-01

The development of optically transparent and mechanically flexible electronic circuitry is an essential step in the effort to develop next-generation display technologies, including `see-through' and conformable products. Nanowire transistors (NWTs) are of particular interest for future display devices because of their high carrier mobilities compared with bulk or thin-film transistors made from the same materials, the prospect of processing at low temperatures compatible with plastic substrates, as well as their optical transparency and inherent mechanical flexibility. Here we report fully transparent In2O3 and ZnO NWTs fabricated on both glass and flexible plastic substrates, exhibiting high-performance n-type transistor characteristics with ~82% optical transparency. These NWTs should be attractive as pixel-switching and driving transistors in active-matrix organic light-emitting diode (AMOLED) displays. The transparency of the entire pixel area should significantly enhance aperture ratio efficiency in active-matrix arrays and thus substantially decrease power consumption.

Fabrication of fully transparent nanowire transistors for transparent and flexible electronics.

PubMed

Ju, Sanghyun; Facchetti, Antonio; Xuan, Yi; Liu, Jun; Ishikawa, Fumiaki; Ye, Peide; Zhou, Chongwu; Marks, Tobin J; Janes, David B

2007-06-01

The development of optically transparent and mechanically flexible electronic circuitry is an essential step in the effort to develop next-generation display technologies, including 'see-through' and conformable products. Nanowire transistors (NWTs) are of particular interest for future display devices because of their high carrier mobilities compared with bulk or thin-film transistors made from the same materials, the prospect of processing at low temperatures compatible with plastic substrates, as well as their optical transparency and inherent mechanical flexibility. Here we report fully transparent In(2)O(3) and ZnO NWTs fabricated on both glass and flexible plastic substrates, exhibiting high-performance n-type transistor characteristics with approximately 82% optical transparency. These NWTs should be attractive as pixel-switching and driving transistors in active-matrix organic light-emitting diode (AMOLED) displays. The transparency of the entire pixel area should significantly enhance aperture ratio efficiency in active-matrix arrays and thus substantially decrease power consumption.

Effect of reduced graphene oxide-carbon nanotubes hybrid nanofillers in mechanical properties of polymer nanocomposites

NASA Astrophysics Data System (ADS)

Sa, Kadambinee; Mahakul, Prakash C.; Subramanyam, B. V. R. S.; Raiguru, Jagatpati; Das, Sonali; Alam, Injamul; Mahanandia, Pitamber

2018-03-01

Graphene and carbon nanotubes (CNTs) have tremendous interest as reinforcing fillers due to their excellent physical properties. However, their reinforcing effect in polymer matrix is limited due to agglomeration of graphene and CNTs within the polymer matrix. Mechanical properties by the admixture of reduced graphene oxide (rGO) and CNTs in Poly (methyl methacrylate) (PMMA) prepared by solution mixing method has been investigated. The prepared samples are characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy. The hybrid composite shows improvement in the mechanical properties compared to rGO/PMMA and MWCNTs/PMMA composites due to better interaction between rGO-MWCNTs and polymer matrix.

Flexible transparent conducting hybrid film using a surface-embedded copper nanowire network: a highly oxidation-resistant copper nanowire electrode for flexible optoelectronics.

PubMed

Im, Hyeon-Gyun; Jung, Soo-Ho; Jin, Jungho; Lee, Dasom; Lee, Jaemin; Lee, Daewon; Lee, Jung-Yong; Kim, Il-Doo; Bae, Byeong-Soo

2014-10-28

We report a flexible high-performance conducting film using an embedded copper nanowire transparent conducting electrode; this material can be used as a transparent electrode platform for typical flexible optoelectronic devices. The monolithic composite structure of our transparent conducting film enables simultaneously an outstanding oxidation stability of the copper nanowire network (14 d at 80 °C), an exceptionally smooth surface topography (R(rms) < 2 nm), and an excellent opto-electrical performances (Rsh = 25 Ω sq(-1) and T = 82%). A flexible organic light emitting diode device is fabricated on the transparent conducting film to demonstrate its potential as a flexible copper nanowire electrode platform.

Electrohydrodynamic printing of silver nanowires for flexible and stretchable electronics.

PubMed

Cui, Zheng; Han, Yiwei; Huang, Qijin; Dong, Jingyan; Zhu, Yong

2018-04-19

A silver nanowire (AgNW) based conductor is a promising component for flexible and stretchable electronics. A wide range of flexible/stretchable devices using AgNW conductors has been demonstrated recently. High-resolution, high-throughput printing of AgNWs remains a critical challenge. Electrohydrodynamic (EHD) printing has been developed as a promising technique to print different materials on a variety of substrates with high resolution. Here, AgNW ink was developed for EHD printing. The printed features can be controlled by several parameters including AgNW concentration, ink viscosity, printing speed, stand-off distance, etc. With this method, AgNW patterns can be printed on a range of substrates, e.g. paper, polyethylene terephthalate (PET), glass, polydimethylsiloxane (PDMS), etc. First, AgNW samples on PDMS were characterized under bending and stretching. Then AgNW heaters and electrocardiogram (ECG) electrodes were fabricated to demonstrate the potential of this printing technique for AgNW-based flexible and stretchable devices.

RGO-coated elastic fibres as wearable strain sensors for full-scale detection of human motions

NASA Astrophysics Data System (ADS)

Mi, Qing; Wang, Qi; Zang, Siyao; Mao, Guoming; Zhang, Jinnan; Ren, Xiaomin

2018-01-01

In this study, we chose highly-elastic fabric fibres as the functional carrier and then simply coated the fibres with reduced graphene oxide (rGO) using plasma treatment, dip coating and hydrothermal reduction steps, finally making a wearable strain sensor. As a result, the full-scale detection of human motions, ranging from bending joints to the pulse beat, has been achieved by these sensors. Moreover, high sensitivity, good stability and excellent repeatability were realized. The good sensing performances and economical fabrication process of this wearable strain sensor have strengthened our confidence in practical applications in smart clothing, smart fabrics, healthcare, and entertainment fields.

The Optical Properties of Thin Film Reduced Graphene Oxide/Poly (3,4 Ethylenedioxtriophene):Poly (Styrene Sulfonate)(PEDOT:PSS) Fabricated by Spin Coating

NASA Astrophysics Data System (ADS)

Rokmana, Arinta W.; Asriani, A.; Suhendar, H.; Triyana, K.; Kusumaatmaja, A.; Santoso, I.

2018-04-01

Reduced Graphene Oxide (rGO) has been successfully synthesized from Graphite powder through chemical process using modified Hummers method by removing NaNO3 from reaction formula. Hydrazine hydrate 80 wt% has been chosen as reductor to eliminate the epoxy group in GO. FTIR and Uv-Vis spectroscopy result showed that Graphene Oxide (GO) and rGO were formed. Our produced rGO then used to fabricated the composite thin film rGO/PEDOT:PSS by spin coating at room temperature. The optical constant of thin film rGO/PEDOT:PSS were calculated from the absorbance spectrum of Uv-Visible spectra. The result showed that the value of coefficient absorbance of rGO dropped from 4.7×106 m-1 to 1.3×106 m-1 after doped with 0.02 mL PEDOT:PSS, then increase with the addition volume concentration of PEDOT:PSS. The value of extinction coefficient decrease from 0.31 to 0.08 after rGO doped with 0.02 ml PEDOT:PSS and then increase with the addition concentration of PEDOT:PSS. Our result show that thin film rGO/PEDOT:PSS was more transparent than that of thin film rGO.

A flexible UV nanosensor based on reduced graphene oxide decorated ZnO nanostructures

NASA Astrophysics Data System (ADS)

Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Muhammad, Safdar; Huang, Ying; He, Jun

2012-03-01

A low-cost, compatible with flexible electronics, high performance UV sensor has been achieved from a reduced graphene oxide (RGO) decorated hydrangea-like ZnO film on a PDMS substrate. The hydrangea-like ZnO UV sensor has the best UV sensing performance among devices made of three kinds of ZnO nanostructures synthesized by a hydrothermal method, and demonstrated a dramatic enhancement in on/off ratio and photoresponse current by introducing an appropriate weight ratio of RGO. The on/off ratio of the 0.05% RGO/ZnO sensor increases almost one order of magnitude compared to that of a pristine hydrangea-like ZnO UV sensor. While for the 5% RGO decorated ZnO sensor, the photoresponse current reaches as high as ~1 μA and exceeds 700 times that of a ZnO UV sensor. These results indicate that RGO is an appropriate material to enhance the performance of ZnO nanostructure UV sensors based on its unique features, especially the high optical transparency and excellent electronic conductivity. Our findings will make RGO/ZnO nanohybrids extraordinarily promising in optoelectronics, flexible electronics and sensor applications.

A flexible UV nanosensor based on reduced graphene oxide decorated ZnO nanostructures.

PubMed

Wang, Zhenxing; Zhan, Xueying; Wang, Yajun; Muhammad, Safdar; Huang, Ying; He, Jun

2012-04-21

A low-cost, compatible with flexible electronics, high performance UV sensor has been achieved from a reduced graphene oxide (RGO) decorated hydrangea-like ZnO film on a PDMS substrate. The hydrangea-like ZnO UV sensor has the best UV sensing performance among devices made of three kinds of ZnO nanostructures synthesized by a hydrothermal method, and demonstrated a dramatic enhancement in on/off ratio and photoresponse current by introducing an appropriate weight ratio of RGO. The on/off ratio of the 0.05% RGO/ZnO sensor increases almost one order of magnitude compared to that of a pristine hydrangea-like ZnO UV sensor. While for the 5% RGO decorated ZnO sensor, the photoresponse current reaches as high as ∼1 μA and exceeds 700 times that of a ZnO UV sensor. These results indicate that RGO is an appropriate material to enhance the performance of ZnO nanostructure UV sensors based on its unique features, especially the high optical transparency and excellent electronic conductivity. Our findings will make RGO/ZnO nanohybrids extraordinarily promising in optoelectronics, flexible electronics and sensor applications.

Role of RGO support and irradiation source on the photocatalytic activity of CdS–ZnO semiconductor nanostructures

PubMed Central

Kumar, Suneel; Sharma, Rahul; Sharma, Vipul; Harith, Gurunarayanan; Sivakumar, Vaidyanathan

2016-01-01

Photocatalytic activity of semiconductor nanostructures is gaining much importance in recent years in both energy and environmental applications. However, several parameters play a crucial role in enhancing or suppressing the photocatalytic activity through, for example, modifying the band gap energy positions, influencing the generation and transport of charge carriers and altering the recombination rate. In this regard, physical parameters such as the support material and the irradiation source can also have significant effect on the activity of the photocatalysts. In this work, we have investigated the role of reduced graphene oxide (RGO) support and the irradiation source on mixed metal chalcogenide semiconductor (CdS–ZnO) nanostructures. The photocatalyst material was synthesized using a facile hydrothermal method and thoroughly characterized using different spectroscopic and microscopic techniques. The photocatalytic activity was evaluated by studying the degradation of a model dye (methyl orange, MO) under visible light (only) irradiation and under natural sunlight. The results reveal that the RGO-supported CdS–ZnO photocatalyst performs considerably better than the unsupported CdS–ZnO nanostructures. In addition, both the catalysts perform significantly better under natural sunlight than under visible light (only) irradiation. In essence, this work paves way for tailoring the photocatalytic activity of semiconductor nanostructures. PMID:28144518

Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in- situ formed lanthanide complexes

NASA Astrophysics Data System (ADS)

Wang, Yige; Wang, Li; Li, Huanrong; Liu, Peng; Qin, Dashan; Liu, Binyuan; Zhang, Wenjun; Deng, Ruiping; Zhang, Hongjie

2008-03-01

Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film. TEM image shows that the in-situ formed lanthanide complexes were homogeneously distributed throughout the whole thin film. The quantum yield and the number of water coordinated to lanthanide metal center have been theoretically determined based on the luminescence data.

Ureasil-polyether hybrid film-forming materials.

PubMed

Souza, L K; Bruno, C H; Lopes, L; Pulcinelli, S H; Santilli, C V; Chiavacci, L A

2013-01-01

The objectives of this work were to study the suitability and highlight the advantages of the use of cross-linked ureasil-polyether hybrid matrices as film-forming systems. The results revealed that ureasil-polyethers are excellent film-forming systems due to specific properties, such as their biocompatibility, their cosmetic attractiveness for being able to form thin and transparent films, their short drying time to form films and their excellent bioadhesion compared to the commercial products known as strong adhesives. Rheological measurements have demonstrated the ability of these hybrid matrices to form a film in only a few seconds and Water Vapor Transmitting Rate (WVTR) showed adequate semi-occlusive properties suggesting that these films could be used as skin and wound protectors. Both the high skin bioadhesion and non-cytotoxic character seems to be improved by the presence of multiple amine groups in the hybrid molecules. Copyright © 2012 Elsevier B.V. All rights reserved.

Absorption enhancement in non-coplanar silver nanowire networks

NASA Astrophysics Data System (ADS)

He, Zhihui; Zhou, Zhiping; Ren, Xincheng; Bai, Shaomin; Li, Hongjian; Cao, Dongmei; Li, Gang; Cao, Guangtao

2018-07-01

We propose non-coplanar silver nanowire (AgNW) networks placed on a SiO2 layer. A notable absorption peak is observed in our proposed structure, and compared with the absorption of coplanar periodic AgNW networks and periodic AgNW gratings, the absorption performance of the non-coplanar AgNW networks demonstrates obvious advantages. It could be determined that the absorption ratio in this non-coplanar AgNW networks can reach 95%. In addition, several parameters that have important effects on the absorption of the non-coplanar AgNW networks are discussed in detail. Our research may provide guidance for the fundamental exploration of plasmonic absorption device applications.

Highly Stretchable and Conductive Silver Nanoparticle Embedded Graphene Flake Electrode Prepared by In situ Dual Reduction Reaction

PubMed Central

Yoon, Yeoheung; Samanta, Khokan; Lee, Hanleem; Lee, Keunsik; Tiwari, Anand P.; Lee, JiHun; Yang, Junghee; Lee, Hyoyoung

2015-01-01

The emergence of stretchable devices that combine with conductive properties offers new exciting opportunities for wearable applications. Here, a novel, convenient and inexpensive solution process was demonstrated to prepare in situ silver (Ag) or platinum (Pt) nanoparticles (NPs)-embedded rGO hybrid materials using formic acid duality in the presence of AgNO3 or H2PtCl6 at low temperature. The reduction duality of the formic acid can convert graphene oxide (GO) to rGO and simultaneously deposit the positively charged metal ion to metal NP on rGO while the formic acid itself is converted to a CO2 evolving gas that is eco-friendly. The AgNP-embedded rGO hybrid electrode on an elastomeric substrate exhibited superior stretchable properties including a maximum conductivity of 3012 S cm-1 (at 0 % strain) and 322.8 S cm-1 (at 35 % strain). Its fabrication process using a printing method is scalable. Surprisingly, the electrode can survive even in continuous stretching cycles. PMID:26383845

Solution of reduced graphene oxide synthesized from coconut shells and its optical properties

NASA Astrophysics Data System (ADS)

Mas'udah, Kusuma Wardhani; Nugraha, I. Made Ananta; Abidin, Saiful; Mufid, Ali; Astuti, Fahmi; Darminto

2016-04-01

Reduced graphene oxide (r-GO)powder has been prepared from coconut shells by carbonization process at 400°C for 3, 4 and 5 hours.Theresulted sample mass was reduced to be 60% relativelycompared to the starting material. The longer heating duration has also led to the rGO with reduced crystalinity according to the X-ray diffractometry data and TEM. The rGO solution was prepared by adding powders of 5, 10 and 15 grams into 50 ml destiled water and then centrifused at 6000 rpm for 30 minutes.The resulted solutions were seen to be varied form clear transparant, light and dark yellow to black. Measurement using particle size analyser shows that the individual rGO particles tends to be agglomerating each others to form bigger size clustering, manifested by the observed bigger size particles for the increasing amount of soluted rGO powders in water.The varying UV-visible spectra of these rGO solutions together with their optical bandgaps will also be discussed in this study.

Solution of reduced graphene oxide synthesized from coconut shells and its optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mas’udah, Kusuma Wardhani, E-mail: masudahkusuma@ymail.com; Faculty of Mathematics and Natural Sciences, Univesitas Pesantren Tinggi Darul Ulum, PP. Darul ‘Ulum Tromol Pos 10 Peterongan Jombang 61481; Nugraha, I Made Ananta, E-mail: anantanugraha25@gmail.com

Reduced graphene oxide (r-GO)powder has been prepared from coconut shells by carbonization process at 400°C for 3, 4 and 5 hours.Theresulted sample mass was reduced to be 60% relativelycompared to the starting material. The longer heating duration has also led to the rGO with reduced crystalinity according to the X-ray diffractometry data and TEM. The rGO solution was prepared by adding powders of 5, 10 and 15 grams into 50 ml destiled water and then centrifused at 6000 rpm for 30 minutes.The resulted solutions were seen to be varied form clear transparant, light and dark yellow to black. Measurement using particle sizemore » analyser shows that the individual rGO particles tends to be agglomerating each others to form bigger size clustering, manifested by the observed bigger size particles for the increasing amount of soluted rGO powders in water.The varying UV-visible spectra of these rGO solutions together with their optical bandgaps will also be discussed in this study.« less

Light harvesting and charge management by Ni4S3 modified metal-organic frameworks and rGO in the process of photocatalysis.

PubMed

Liu, Duanduan; Jin, Zhiliang; Zhang, Yongke; Wang, Guorong; Ma, Bingzhen

2018-06-01

Harvesting and charge management is obtained by means of Ni 4 S 3 modified Metal-organic Frameworks (MOF) and rGO, namely, the Uio-66 (Zr)/rGO combined with Ni 4 S 3 photocatalyst was successfully prepared with the solvothermal method. The Ni 4 S 3 acted as the electron transfer agent greatly improve the electrons transmission from the excited state dye to the rGO/MOF surface for proton reduction reaction. The hydrogen production amount over EY-sensitized rGO/MOF/Ni 4 S 3 photocatalyst has reached 280 μmol for 5 h, which is about 14 times than that of the pure Ni 4 S 3 photocatalyst and 185 times than that of the pure rGO/MOF photocatalyst under visible light irradiation (λ ≥ 420 nm). In the composite, the rGO acts as electron-transfer mediator and Ni 4 S 3 serves as H 2 -evolution active site. A series of studies shown that the Ni 4 S 3 modified MOF and rGO provided more active sites and improved the efficiency of photo-generated charge separation by means of several characterizations such as SEM, XRD, XPS, Element Mapping, UV-vis DRS, BET, Photocurrent, Voltammetric Scanning, Fluorescence Spectra and FTIR. and the results of which were in good agreement with each other. The photoelectron migration rate and photogenerated charge separation efficiency of the composite can be obviously increased with graphene as a good electron acceptor and transfer medium and Ni 4 S 3 as hydrogen producing active site. Copyright © 2018 Elsevier Inc. All rights reserved.

Hazy Transparent Cellulose Nanopaper

PubMed Central

Hsieh, Ming-Chun; Koga, Hirotaka; Suganuma, Katsuaki; Nogi, Masaya

2017-01-01

The aim of this study is to clarify light scattering mechanism of hazy transparent cellulose nanopaper. Clear optical transparent nanopaper consists of 3–15 nm wide cellulose nanofibers, which are obtained by the full nanofibrillation of pulp fibers. At the clear transparent nanopaper with 40 μm thickness, their total transmittance are 89.3–91.5% and haze values are 4.9–11.7%. When the pulp fibers are subjected to weak nanofibrillation, hazy transparent nanopapers are obtained. The hazy transparent nanopaper consists of cellulose nanofibers and some microsized cellulose fibers. At the hazy transparent nanopaper with 40 μm thickness, their total transmittance were constant at 88.6–92.1% but their haze value were 27.3–86.7%. Cellulose nanofibers are solid cylinders, whereas the pulp fibers are hollow cylinders. The hollow shape is retained in the microsized cellulose fibers, but they are compressed flat inside the nanopaper. This compressed cavity causes light scattering by the refractive index difference between air and cellulose. As a result, the nanopaper shows a hazy transparent appearance and exhibits a high thermal durability (295–305 °C), and low thermal expansion (8.5–10.6 ppm/K) because of their high density (1.29–1.55 g/cm3) and crystallinity (73–80%). PMID:28128326

High Temperature Transparent Furnace Development

NASA Technical Reports Server (NTRS)

Bates, Stephen C.

1997-01-01

This report describes the use of novel techniques for heat containment that could be used to build a high temperature transparent furnace. The primary objective of the work was to experimentally demonstrate transparent furnace operation at 1200 C. Secondary objectives were to understand furnace operation and furnace component specification to enable the design and construction of a low power prototype furnace for delivery to NASA in a follow-up project. The basic approach of the research was to couple high temperature component design with simple concept demonstration experiments that modify a commercially available transparent furnace rated at lower temperature. A detailed energy balance of the operating transparent furnace was performed, calculating heat losses through the furnace components as a result of conduction, radiation, and convection. The transparent furnace shells and furnace components were redesigned to permit furnace operation at at least 1200 C. Techniques were developed that are expected to lead to significantly improved heat containment compared with current transparent furnaces. The design of a thermal profile in a multizone high temperature transparent furnace design was also addressed. Experiments were performed to verify the energy balance analysis, to demonstrate some of the major furnace improvement techniques developed, and to demonstrate the overall feasibility of a high temperature transparent furnace. The important objective of the research was achieved: to demonstrate the feasibility of operating a transparent furnace at 1200 C.

Luminescent and transparent nanopaper based on rare-earth up-converting nanoparticle grafted nanofibrillated cellulose derived from garlic skin.

PubMed

Zhao, Jingpeng; Wei, Zuwu; Feng, Xin; Miao, Miao; Sun, Lining; Cao, Shaomei; Shi, Liyi; Fang, Jianhui

2014-09-10

Highly flexible, transparent, and luminescent nanofibrillated cellulose (NFC) nanopaper with heterogeneous network, functionalized by rare-earth up-converting luminescent nanoparticles (UCNPs), was rapidly synthesized by using a moderate pressure extrusion paper-making process. NFC was successfully prepared from garlic skin using an efficient extraction approach combined with high frequency ultrasonication and high pressure homogenization after removing the noncellulosic components. An efficient epoxidation treatment was carried out to enhance the activity of the UCNPs (NaYF4:Yb,Er) with oleic acid ligand capped on the surface. The UCNPs after epoxidation then reacted with NFC in aqueous medium to form UCNP-grafted NFC nanocomposite (NFC-UCNP) suspensions at ambient temperature. Through the paper-making process, the assembled fluorescent NFC-UCNP hybrid nanopaper exhibits excellent properties, including high transparency, strong up-conversion luminescence, and good flexibility. The obtained hybrid nanopaper was characterized by transmission electron microscopy (TEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), field emission-scanning electron microscope (FE-SEM), up-conversion luminescence (UCL) spectrum, and ultraviolet and visible (UV-vis) spectrophotometer. The experimental results demonstrate that the UCNPs have been successfully grafted to the NFC matrix with heterogeneous network. And the superiorly optical transparent and luminescent properties of the nanopaper mainly depend on the ratio of UCNPs to NFC. Of importance here is that, NFC and UCNPs afford the nanopaper a prospective candidate for multimodal anti-counterfeiting, sensors, and ion probes applications.

Perceptual transparency from image deformation.

PubMed

Kawabe, Takahiro; Maruya, Kazushi; Nishida, Shin'ya

2015-08-18

Human vision has a remarkable ability to perceive two layers at the same retinal locations, a transparent layer in front of a background surface. Critical image cues to perceptual transparency, studied extensively in the past, are changes in luminance or color that could be caused by light absorptions and reflections by the front layer, but such image changes may not be clearly visible when the front layer consists of a pure transparent material such as water. Our daily experiences with transparent materials of this kind suggest that an alternative potential cue of visual transparency is image deformations of a background pattern caused by light refraction. Although previous studies have indicated that these image deformations, at least static ones, play little role in perceptual transparency, here we show that dynamic image deformations of the background pattern, which could be produced by light refraction on a moving liquid's surface, can produce a vivid impression of a transparent liquid layer without the aid of any other visual cues as to the presence of a transparent layer. Furthermore, a transparent liquid layer perceptually emerges even from a randomly generated dynamic image deformation as long as it is similar to real liquid deformations in its spatiotemporal frequency profile. Our findings indicate that the brain can perceptually infer the presence of "invisible" transparent liquids by analyzing the spatiotemporal structure of dynamic image deformation, for which it uses a relatively simple computation that does not require high-level knowledge about the detailed physics of liquid deformation.

Nanowelding and patterning of silver nanowires via mask-free atmospheric cold plasma-jet scanning

NASA Astrophysics Data System (ADS)

Liu, Lang; Li, Han-Yu; Ye, Dong; Yu, Yao; Liu, Lin; Wu, Yue

2017-06-01

Silver nanowire (AgNW) thin film is a promising candidate to replace traditional indium tin oxide in optoelectronics applications. To date however, the widespread application of AgNW thin film is limited by the weak point contacts between individual AgNWs and the lack of facile patterning techniques. Here, we demonstrate a novel and facile method to not only nanoweld AgNW junctions but also pattern AgNW thin films via mask-free cold plasma-jet scanning in ambient conditions. After the plasma-jet nanowelding treatment, the morphology of AgNWs change substantially and the junctions are welded together. The nanowelded AgNWs-based thin film shows enhanced electrical and mechanical properties. On the other hand, after the plasma-jet patterning treatment, the AgNWs are etched and transformed into separated large particles. Different kinds of patterns are produced via this patterning technique. At last, a simple light emitting diode circuit is fabricated to demonstrate the suitability of the nanowelded and patterned AgNW electrodes for flexible electronic devices.

Lignin-Retaining Transparent Wood.

PubMed

Li, Yuanyuan; Fu, Qiliang; Rojas, Ramiro; Yan, Min; Lawoko, Martin; Berglund, Lars

2017-09-11

Optically transparent wood, combining optical and mechanical performance, is an emerging new material for light-transmitting structures in buildings with the aim of reducing energy consumption. One of the main obstacles for transparent wood fabrication is delignification, where around 30 wt % of wood tissue is removed to reduce light absorption and refractive index mismatch. This step is time consuming and not environmentally benign. Moreover, lignin removal weakens the wood structure, limiting the fabrication of large structures. A green and industrially feasible method has now been developed to prepare transparent wood. Up to 80 wt % of lignin is preserved, leading to a stronger wood template compared to the delignified alternative. After polymer infiltration, a high-lignin-content transparent wood with transmittance of 83 %, haze of 75 %, thermal conductivity of 0.23 W mK -1 , and work-tofracture of 1.2 MJ m -3 (a magnitude higher than glass) was obtained. This transparent wood preparation method is efficient and applicable to various wood species. The transparent wood obtained shows potential for application in energy-saving buildings. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Lignin‐Retaining Transparent Wood

PubMed Central

Fu, Qiliang; Rojas, Ramiro; Yan, Min; Lawoko, Martin

2017-01-01

Abstract Optically transparent wood, combining optical and mechanical performance, is an emerging new material for light‐transmitting structures in buildings with the aim of reducing energy consumption. One of the main obstacles for transparent wood fabrication is delignification, where around 30 wt % of wood tissue is removed to reduce light absorption and refractive index mismatch. This step is time consuming and not environmentally benign. Moreover, lignin removal weakens the wood structure, limiting the fabrication of large structures. A green and industrially feasible method has now been developed to prepare transparent wood. Up to 80 wt % of lignin is preserved, leading to a stronger wood template compared to the delignified alternative. After polymer infiltration, a high‐lignin‐content transparent wood with transmittance of 83 %, haze of 75 %, thermal conductivity of 0.23 W mK−1, and work‐tofracture of 1.2 MJ m−3 (a magnitude higher than glass) was obtained. This transparent wood preparation method is efficient and applicable to various wood species. The transparent wood obtained shows potential for application in energy‐saving buildings. PMID:28719095

Semi-transparent solar cells

NASA Astrophysics Data System (ADS)

Sun, J.; Jasieniak, J. J.

2017-03-01

Semi-transparent solar cells are a type of technology that combines the benefits of visible light transparency and light-to-electricity conversion. One of the biggest opportunities for such technologies is in their integration as windows and skylights within energy-sustainable buildings. Currently, such building integrated photovoltaics (BIPV) are dominated by crystalline silicon based modules; however, the opaque nature of silicon creates a unique opportunity for the adoption of emerging photovoltaic candidates that can be made truly semi-transparent. These include: amorphous silicon-, kesterite-, chalcopyrite-, CdTe-, dye-sensitized-, organic- and perovskite- based systems. For the most part, amorphous silicon has been the workhorse in the semi-transparent solar cell field owing to its established, low-temperature fabrication processes. Excitement around alternative classes, particularly perovskites and the inorganic candidates, has recently arisen because of the major efficiency gains exhibited by these technologies. Importantly, each of these presents unique opportunities and challenges within the context of BIPV. This topic review provides an overview into the broader benefits of semi-transparent solar cells as building-integrated features, as well as providing the current development status into all of the major types of semi-transparent solar cells technologies.

Deterministic growth of AgTCNQ and CuTCNQ nanowires on large-area reduced graphene oxide films for flexible optoelectronics.

PubMed

Zhang, Shuai; Lu, Zhufeng; Gu, Li; Cai, Liling; Cao, Xuebo

2013-11-22

We describe a synchronous reduction and assembly procedure to directly produce large-area reduced graphene oxide (rGO) films sandwiched by a high density of metal nanoparticles (silver and copper). Further, by using the sandwiched metal NPs as sources, networks consisting of AgTCNQ and CuTCNQ nanowires were deterministically grown from the rGO films, forming structurally and functionally integrated rGO/metal-TCNQ hybrid films with outstanding flexibility, bending endurance, and electrical stability. Interestingly, due to the p-type nature of the rGO film and the n-type nature of the metal-TCNQ NWs, the hybrid films are essentially thin-film p-n junctions which are useful in ubiquitous electronics and optoelectronics. Measurements of the optoelectronic properties demonstrate that the rGO/metal-TCNQ hybrid films exhibit substantial photoconductivity and highly reproducible photoswitching behaviours. The present approach may open the door to the versatile and deterministic integration of functional nanostructures into flexible conducting substrates and provide an important step towards producing low-cost and high-performance soft electronic and optoelectronic devices.

Second-order nonlinearity induced transparency.

PubMed

Zhou, Y H; Zhang, S S; Shen, H Z; Yi, X X

2017-04-01

In analogy to electromagnetically induced transparency, optomechanically induced transparency was proposed recently in [Science330, 1520 (2010)SCIEAS0036-807510.1126/science.1195596]. In this Letter, we demonstrate another form of induced transparency enabled by second-order nonlinearity. A practical application of the second-order nonlinearity induced transparency is to measure the second-order nonlinear coefficient. Our scheme might find applications in quantum optics and quantum information processing.

Multilayered Si nanoparticle/reduced graphene oxide hybrid as a high-performance lithium-ion battery anode.

PubMed

Chang, Jingbo; Huang, Xingkang; Zhou, Guihua; Cui, Shumao; Hallac, Peter B; Jiang, Junwei; Hurley, Patrick T; Chen, Junhong

2014-02-01

Multilayered Si/RGO anode nanostructures, featuring alternating Si nanoparticle (NP) and RGO layers, good mechanical stability, and high electrical conductivity, allow Si NPs to easily expand between RGO layers, thereby leading to high reversible capacity up to 2300 mAh g(-1) at 0.05 C (120 mA g(-1) ) and 87% capacity retention (up to 630 mAh g(-1) ) at 10 C after 152 cycles. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid rendering of the chest and virtual bronchoscopy [corrected].

PubMed

Seemann, M D; Seemann, O; Luboldt, W; Gebicke, K; Prime, G; Claussen, C D

2000-10-30

Thin-section spiral computed tomography was used to acquire the volume data sets of the thorax. The tracheobronchial system and pathological changes of the chest were visualized using a color-coded surface rendering method. The structures of interest were then superimposed on a volume rendering of the other thoracic structures, thus producing a hybrid rendering. The hybrid rendering technique exploit the advantages of both rendering methods and enable virtual bronchoscopic examinations using different representation models. Virtual bronchoscopic examinations with a transparent color-coded shaded-surface model enables the simultaneous visualization of both the airways and the adjacent structures behind of the tracheobronchial wall and therefore, offers a practical alternative to fiberoptic bronchoscopy. Hybrid rendering and virtual endoscopy obviate the need for time consuming detailed analysis and presentation of axial source images.

Wearable, wireless gas sensors using highly stretchable and transparent structures of nanowires and graphene

NASA Astrophysics Data System (ADS)

Park, Jihun; Kim, Joohee; Kim, Kukjoo; Kim, So-Yun; Cheong, Woon Hyung; Park, Kyeongmin; Song, Joo Hyeb; Namgoong, Gyeongho; Kim, Jae Joon; Heo, Jaeyeong; Bien, Franklin; Park, Jang-Ung

2016-05-01

Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the `Internet of Things' area.Herein, we report the fabrication of a highly stretchable, transparent gas sensor based on silver nanowire-graphene hybrid nanostructures. Due to its superb mechanical and optical characteristics, the fabricated sensor demonstrates outstanding and stable performances even under extreme mechanical deformation (stable until 20% of strain). The integration of a Bluetooth system or an inductive antenna enables the wireless operation of the sensor. In addition, the mechanical robustness of the materials allows the device to be transferred onto various nonplanar substrates, including a watch, a bicycle light, and the leaves of live plants, thereby achieving next-generation sensing electronics for the `Internet of Things' area. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01468b

Transparent conductive coatings

NASA Technical Reports Server (NTRS)

Ashok, S.

1983-01-01

Thin film transparent conductors are discussed. Materials with electrical conductivity and optical transparency are highly desirable in many optoelectronic applications including photovoltaics. Certain binary oxide semiconductors such as tin oxide (SnO2) and indium oxide (In2O3) offer much better performance tradeoff in optoelectronics as well as better mechanical and chemical stability than thin semitransparent films. These thin-film transparent conductors (TC) are essentially wide-bandgap degenerate semiconductors - invariably n-type - and hence are transparent to sub-bandgap (visible) radiation while affording high electrical conductivity due to the large free electron concentration. The principal performance characteristics of TC's are, of course, electrical conductivity and optical transmission. The TC's have a refractive index of around 2.0 and hence act as very efficient antireflection coatings. For using TC's in surface barrier solar cells, the photovoltaic barrier is of utmost importance and so the work function or electron affinity of the TC is also a very important material parameter. Fabrication processes are discussed.

Theoretical realization of robust broadband transparency in ultrathin seamless nanostructures by dual blackbodies for near infrared light

NASA Astrophysics Data System (ADS)

Zhang, Lei; Hao, Jiaming; Ye, Huapeng; Yeo, Swee Ping; Qiu, Min; Zouhdi, Said; Qiu, Cheng-Wei

2013-03-01

We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by varying the geometric dimension. More significantly, from the point view of applications, the proposed method of achieving broadband transparency can perfectly tolerate the misalignment and asymmetry of periodic nanoparticles on the top and bottom, which is empowered by the unique dual of coupling-in and coupling-out processes within the pair of blackbodies. Moreover, roughness has little influence on its transmission performance. According to the coupled mode theory, the distinguished transmittance performance is physically interpreted by the radiative decay rate of the entire system. In addition to the feature of uniquely robust broadband transparency, such a ultrathin seamless nanostructure (in the presence of a uniform silver layer) also provides polarization-independent and angle-independent operations. Therefore, it may power up a wide spectrum of exciting applications in thin film protection, touch screen techniques, absorber-emitter transformation, etc.We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by

Positron annihilation in transparent ceramics

NASA Astrophysics Data System (ADS)

Husband, P.; Bartošová, I.; Slugeň, V.; Selim, F. A.

2016-01-01

Transparent ceramics are emerging as excellent candidates for many photonic applications including laser, scintillation and illumination. However achieving perfect transparency is essential in these applications and requires high technology processing and complete understanding for the ceramic microstructure and its effect on the optical properties. Positron annihilation spectroscopy (PAS) is the perfect tool to study porosity and defects. It has been applied to investigate many ceramic structures; and transparent ceramics field may be greatly advanced by applying PAS. In this work positron lifetime (PLT) measurements were carried out in parallel with optical studies on yttrium aluminum garnet transparent ceramics in order to gain an understanding for their structure at the atomic level and its effect on the transparency and light scattering. The study confirmed that PAS can provide useful information on their microstructure and guide the technology of manufacturing and advancing transparent ceramics.

Tungsten disulfide nanoparticles anchored on reduced graphene oxide for dye sensitized solar cell applications

NASA Astrophysics Data System (ADS)

Kumar, Sanjeev; Prakash, Om; Mahajan, Aman; Saxena, Vibha

2018-04-01

We herein describe hydrothermal method to prepare a hybrid material consisting of tungsten disulfide (WS2) nanoparticles anchored onto reduced graphene oxide (rGO) sheets. Synthesized materials have been characterized for structural, compositional and optical properties by different techniques. Results show that WS2 nanoparticles are uniformly anchored ontoas well as in between the surface of rGO which helps to inflate the exfoliation of rGO stacked layers. Thus, the rGO/WS2 hybridcan be used as counter electrode (CE) in dye sensitized solar cells (DSSCs).

Role of graphene on the surface chemical reactions of BiPO4-rGO with low OH-related defects.

PubMed

Gao, Erping; Wang, Wenzhong

2013-11-21

Graphene has been widely introduced into photocatalysis to enhance photocatalytic performance due to its unique physical and chemical properties. However, the effect of graphene on the surface chemical reactions of photocatalysis has not been clearly researched, which is important for photocatalysis because photocatalytic reactions ultimately occur on the catalyst surface. Herein, a two-step solution-phase reaction has been designed to synthesize quasi-core-shell structured BiPO4-rGO cuboids and the role of graphene on the surface chemical reactions was investigated in detail. It was found that the introduced graphene modified the process and the mechanism of the surface chemical reactions. The change mainly originates from the interaction between graphene and the adsorbed O2 molecule. Due to the electron transfer from graphene to adsorbed O2, graphene could tune the interfacial charge transport and efficiently activate molecular oxygen to form O2˙(-) anions as the major oxidation species instead of ˙OH. In addition, the two-step synthesis approach could efficiently suppress the formation of OH-related defects in the lattice. As a result, the BiPO4-rGO composite exhibited superior photocatalytic activity to BiPO4 and P25, about 4.3 times that of BiPO4 and 6.9 times that of P25.

Hybrid single mode lasers fabricated using Si/SiO2/SiON micromachined platforms

NASA Technical Reports Server (NTRS)

Ksendzov, A.; Mansour, K.

2003-01-01

We have devised a hybridization scheme that, given suitable Fabri-Perot (F-P) ain medium, allows us to fabricate small, mechanically robust single frequency lasers in a wide spectral range, limited only by the transparency of the SiON material.

Multi-biofunctional polymer graphene composite for bone tissue regeneration that elutes copper ions to impart angiogenic, osteogenic and bactericidal properties.

PubMed

Jaidev, L R; Kumar, Sachin; Chatterjee, Kaushik

2017-11-01

Despite several recent advances, poor vascularization in implanted scaffolds impedes complete regeneration for clinical success of bone tissue engineering. The present study aims to develop a multi-biofunctional nanocomposite for bone tissue regeneration using copper nanoparticle decorated reduced graphene oxide (RGO_Cu) hybrid particles in polycaprolactone (PCL) matrix (PCL/RGO_Cu). X-ray photoelectron spectroscopy and X-ray diffraction confirmed the presence of copper oxides (CuO and Cu 2 O) on RGO. Thermogravimetric analysis showed that 11.8% of copper was decorated on RGO. PCL/RGO_Cu exhibited steady release of copper ions in contrast to burst release from the composite containing copper alone (PCL/Cu). PCL/RGO_Cu exhibited highest modulus due to enhanced filler exfoliation. Endothelial cells rapidly proliferated on PCL/RGO_Cu confirming cytocompatibility. The sustained release of ions from PCL/RGO_Cu composites augmented tube formation by endothelial cells evidenced enhanced angiogenic activity. Gene expression of angiogenic markers VEGF and ANG-2 was higher on PCL/RGO_Cu compared to PCL. The osteogenic activity of PCL/RGO_Cu was confirmed by the 87% increase in mineral deposition by pre-osteoblasts compared to PCL. The bactericidal activity of PCL/RGO_Cu showed 78% reduction in viability of Escherichia coli. Thus, the multi-biofunctional PCL/RGO_Cu composite exhibits angiogenic, osteogenic and bactericidal properties, a step towards addressing some of the critical challenges in bone tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

NiCoO2 flowers grown on the aligned-flakes coated Ni foam for application in hybrid energy storage

NASA Astrophysics Data System (ADS)

Xu, Xiaoyang; Zhao, Huilin; Zhou, JingKuo; Xue, Ruinan; Gao, Jianping

2016-10-01

Many NiCoO2 flowers with an average diameter of about 4 μm were grown on the NiCoO2 flakes coated Ni foam (denoted as NiCoO2/Ni foam) through a simple hydrothermal method and confirmed by scanning and transmission electron microscopies, X-ray diffraction and X-ray photoelectron spectrum measurements. The NiCoO2/Ni foam with high specific area and porosity was directly used as the working electrode without any binders. The measured specific capacitance of NiCoO2 grown on Ni foam is 756 F/g at 0.75 A/g using a three-electrode setup in 1 M KOH. Considering the high capacity of NiCoO2 and the good stability of rGO, the NiCoO2/Ni foam//rGO hybrid supercapacitor combining NiCoO2/Ni foam and rGO shows very good properties, such as high specific capacitance (82 F/g at 2 A/g based on the total mass of active materials), high energy density (25.7 Wh/kg at 1500 W/kg based on the total mass of active materials), good stability (about 90% capacitance retention after 2000-cycle at 100 mV/s), and low charge ion transfer resistance.

Free-standing ultrathin CoMn2O4 nanosheets anchored on reduced graphene oxide for high-performance supercapacitors.

PubMed

Gao, Guoxin; Lu, Shiyao; Xiang, Yang; Dong, Bitao; Yan, Wei; Ding, Shujiang

2015-11-21

Ultrathin CoMn2O4 nanosheets supported on reduced graphene oxide (rGO) are successfully synthesized through a simple co-precipitation method with a post-annealing treatment. With the assistance of citrate, the free-standing CoMn2O4 ultrathin nanosheets can form porous overlays on both sides of the rGO sheets. Such a novel hybrid nanostructure can effectively promote charge transport and accommodate volume variation upon prolonged charge/discharge cycling. When evaluated as a promising electrode for supercapacitors in a 6 M KOH solution electrolyte, the hybrid nanocomposites demonstrate highly enhanced capacitance and excellent cycling stability.

Determination of nonlinear nanomechanical resonator-qubit coupling coefficient in a hybrid quantum system.

PubMed

Geng, Qi; Zhu, Ka-Di

2016-07-10

We have theoretically investigated a hybrid system that is composed of a traditional optomechanical component and an additional charge qubit (Cooper pair box) that induces a new nonlinear interaction. It is shown that the peak in optomechanically induced transparency has been split by the new nonlinear interaction, and the width of the splitting is proportional to the coupling coefficient of this nonlinear interaction. This may give a way to measure the nanomechanical oscillator-qubit coupling coefficient in hybrid quantum systems.

Photochromic dynamics of organic-inorganic hybrids supported on transparent and flexible recycled PET

NASA Astrophysics Data System (ADS)

Cruz, R. P.; Nalin, M.; Ribeiro, S. J. L.; Molina, C.

2017-04-01

Organic-inorganic hybrids (OIH) synthesized by sol gel process containing phosphotungstic acid (PWA) entrapped have been attracted much attention for ultraviolet sensitive materials. However, the limitations for practical photochromic application of these materials are the poor interaction with flexible polymer substrates such as Poly(ethyleneterephthalate) (PET) and also photo response under ultraviolet radiation. This paper describes the use of the d-ureasil HOI, based on siliceous network grafted through linkages to both ends of polymer chain containing 2.5 poly(oxyethylene) units with PWA entrapped prepared as films on recycled PET. Films were characterized by IR-ATR, XRD, TG/DTG, UV-Vis and Contact angle. XRD patterns showed that both pristine hybrid matrix and those containing PWA are amorphous. IR showed that PWA structure is preserved in the matrix and interactions between them occur by intermolecular forces. Films are thermally stable up to 325 °C and contact angle of 25.1° showed a good wettability between substrate and hybrid matrix. Furthermore, films showed fast photochromic response after 1 min of ultraviolet exposure time. The bleaching process revealed that the relaxation process is dependent of the temperature and the activation energy of 47.2 kJ mol-1 was determined. The properties of these films make them potential candidates for applications in flexible photochromic materials.

Laser Processed Silver Nanowire Network Transparent Electrodes for Novel Electronic Devices

NASA Astrophysics Data System (ADS)

Spechler, Joshua Allen

Silver nanowire network transparent conducting layers are poised to make headway into a space previously dominated by transparent conducting oxides due to the promise of a flexible, scaleable, lab-atmosphere processable alternative. However, there are many challenges standing in the way between research scale use and consumer technology scale adaptation of this technology. In this thesis we will explore many, and overcome a few of these challenges. We will address the poor conductivity at the narrow nanowire-nanowire junction points in the network by developing a laser based process to weld nanowires together on a microscopic scale. We address the need for a comparative metric for transparent conductors in general, by taking a device level rather than a component level view of these layers. We also address the mechanical, physical, and thermal limitations to the silver nanowire networks by making composites from materials including a colorless polyimide and titania sol-gel. Additionally, we verify our findings by integrating these processes into devices. Studying a hybrid organic/inorganic heterojunction photovoltaic device we show the benefits of a laser processed electrode. Green phosphorescent organic light emitting diodes fabricated on a solution phase processed silver nanowire based electrode show favorable device metrics compared to a conductive oxide electrode based control. The work in this thesis is intended to push the adoption of silver nanowire networks to further allow new device architectures, and thereby new device applications.

Toward individually tunable compound eyes with transparent graphene electrode.

PubMed

Shahini, Ali; Jin, Hai; Zhou, Zhixian; Zhao, Yang; Chen, Pai-Yen; Hua, Jing; Cheng, Mark Ming-Cheng

2017-06-08

We present tunable compound eyes made of ionic liquid lenses, of which both curvatures (R 1 and R 2 in the lensmaker's equation) can be individually changed using electrowetting on dielectric (EWOD) and applied pressure. Flexible graphene is used as a transparent electrode and is integrated on a flexible polydimethylsiloxane (PDMS)/parylene hybrid substrate. Graphene electrodes allow a large lens aperture diameter of between 2.4 mm and 2.74 mm. Spherical aberration analysis is performed using COMSOL to investigate the optical property of the lens under applied voltage and pressure. The final lens system shows a resolution of 645.1 line pair per millimeter. A prototype of a tunable lens array is proposed for the application of a compound eye.

Transparency through Structural Disorder: A New Concept for Innovative Transparent Ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al Saghir, Kholoud; Chenu, Sébastien; Veron, Emmanuel

2015-01-27

Transparent polycrystalline ceramics present signi fi cant eco- nomical and functional advantages over single crystal materials for optical, communication, and laser technologies. To date, transparency in these ceramics is ensured either by an optical isotropy (i.e., cubic symmetry) or a nanometric crystallite size, and the main challenge remains to eliminate porosity through complex high pressure - high temperature synthesis. Here we introduce a new concept to achieve ultimate transparency reaching the theoretical limit. We use a controlled degree of chemical disorder in the structure to obtain optical isotropy at the micrometer length scale. This approach can be applied in themore » case of anisotropic structures and micrometer scale crystal size ceramics. We thus report Sr 1+ x /2 Al 2+ x Si 2 - x O 8 (0 < x ≤ 0.4) readily scalable polycrystalline ceramics elaborated by full and congruent crystallization from glass. These materials reach 90% transmittance. This innovative method should drive the development of new highly transparent materials with technologically relevant applications.« less

Fe3O4 nanocubes assembled on RGO nanosheets: Ultrasound induced in-situ and eco-friendly synthesis, characterization and their excellent catalytic performance for the production of liquid fuel in Fischer-tropsch synthesis.

PubMed

Abbas, Mohamed; Zhang, Juan; Lin, Ke; Chen, Jiangang

2018-04-01

In this study, Fe 3 O 4 nanocubes (NCs) decorated on RGO nanosheets (NSs) structures were successfully synthesized through an innovative and environmentally-friendly rapid sonochemical method. More importantly, iron(II) sulfate heptahydrate and GO were employed as precursors and water as reaction medium, meanwhile, NaOH within the generated free radicals from the high intensity ultrasound were sufficient as reducing and base agent in our clean synthesis. Moreover, the hydrothermal method as a conventional approach was employed to synthesize the same catalysts for the comparison with the ultrasonocation technique. The as-synthesized Fe 3 O 4 and RGO/Fe 3 O 4 NSs catalysts were exposed to industrially relevant Fischer-tropsch synthesis (FTS) conditions at various reaction temperatures (250-290 °C), and they subjected to fully characterization before and after FTS reaction using XRD, TEM, HRTEM, EDS mapping, XPS, FTIR, BET, H 2 -TPR, H 2 -TPD and CO-TPD to understand the structure-performance relationships. Notably, the catalysts produced using the sonochemical method had a better CO conversion rate [Fe 3 O 4 (80%), RGO/Fe 3 O 4 (82%)] than the hydrothermally synthesized catalysts. However, compared to the naked-Fe 3 O 4 catalysts, the sonochemically and hydrothermally synthesized RGO-supported Fe 3 O 4 catalysts had higher long chain hydrocarbon (C5+) selectivity values (72% and 67%) and C 2 -C 4 olefin/paraffin selectivity ratio (3.2 and 2) and low CH4 selectivity values (6% and 8.5%), respectively. This can be attributed to their high surface area, the degree of reducibility, and content of Hägg iron carbide (χ-Fe 5 C 2 ) as the most active phase of the FTS reaction. Proposed reaction mechanisms for the sonochemical and hydrothermal reaction synthesis of Fe 3 O 4 and RGO/Fe 3 O 4 nanoparticles are discussed. In conclusion, our developed surfactantless-sonochemical method holds promise for the eco-friendly synthesis of highly efficient catalysts materials for

Flexible Supercapacitors Based on Polyaniline Arrays Coated Graphene Aerogel Electrodes

NASA Astrophysics Data System (ADS)

Yang, Yu; Xi, Yunlong; Li, Junzhi; Wei, Guodong; Klyui, N. I.; Han, Wei

2017-06-01

Flexible supercapacitors(SCs) made by reduced graphene oxide (rGO)-based aerogel usually suffer from the low energy density, short cycle life and bad flexibility. In this study, a new, synthetic strategy was developed for enhancing the electrochemical performances of rGO aerogel-based supercapacitor via electrodeposition polyaniline arrays on the prepared ultralight rGO aerogel. The novel hybrid composites with coated polyaniline (PANI) arrays growing on the rGO surface can take full advantage of the rich open-pore and excellent conductivity of the crosslinking framework structure of 3D rGO aerogel and high capacitance contribution from the PANI. The obtained hybrid composites exhibit excellent electrochemical performance with a specific capacitance of 432 F g-1 at the current density of 1 A g-1, robust cycling stability to maintain 85% after 10,000 charge/discharge cycles and high energy density of 25 W h kg-1. Furthermore, the flexible all-solid-state supercapacitor have superior flexibility and outstanding stability under different bending states from the straight state to the 90° status. The high-performance flexible all-solid-state SCs together with the lighting tests demonstrate it possible for applications in portable electronics.

Flexible Supercapacitors Based on Polyaniline Arrays Coated Graphene Aerogel Electrodes.

PubMed

Yang, Yu; Xi, Yunlong; Li, Junzhi; Wei, Guodong; Klyui, N I; Han, Wei

2017-12-01

Flexible supercapacitors(SCs) made by reduced graphene oxide (rGO)-based aerogel usually suffer from the low energy density, short cycle life and bad flexibility. In this study, a new, synthetic strategy was developed for enhancing the electrochemical performances of rGO aerogel-based supercapacitor via electrodeposition polyaniline arrays on the prepared ultralight rGO aerogel. The novel hybrid composites with coated polyaniline (PANI) arrays growing on the rGO surface can take full advantage of the rich open-pore and excellent conductivity of the crosslinking framework structure of 3D rGO aerogel and high capacitance contribution from the PANI. The obtained hybrid composites exhibit excellent electrochemical performance with a specific capacitance of 432 F g -1 at the current density of 1 A g -1 , robust cycling stability to maintain 85% after 10,000 charge/discharge cycles and high energy density of 25 W h kg -1 . Furthermore, the flexible all-solid-state supercapacitor have superior flexibility and outstanding stability under different bending states from the straight state to the 90° status. The high-performance flexible all-solid-state SCs together with the lighting tests demonstrate it possible for applications in portable electronics.

Cage and linear structured polysiloxane/epoxy hybrids for coatings: Surface property and film permeability.

PubMed

Ma, Yanli; He, Ling; Jia, Mengjun; Zhao, Lingru; Zuo, Yanyan; Hu, Pingan

2017-08-15

Three polysiloxane/epoxy hybrids obtained by evolving cage- or linear-structured polysiloxane into poly glycidyl methacrylate (PGMA) matrix are compared used as coatings. One is the cage-structured hybrid of P(GMA/MA-POSS) copolymer obtained by GMA and methacrylisobutyl polyhedral oligomeric silsesquioxane (MA-POSS) via free radical polymerization, the other two are PGMA/NH 2 -POSS and PGMA/NH 2 -PDMS hybrids by cage-structured aminopropyllsobutyl POSS (NH 2 -POSS) or linear-structured diamino terminated poly(dimethylsiloxane) (NH 2 -PDMS) to cure PGMA. The effect of MA-POSS, NH 2 -POSS and NH 2 -PDMS on polysiloxane/epoxy hybrid films is characterized according to their surface morphology, transparency, permeability, adhesive strength and thermo-mechanical properties. Due to caged POSS tending to agglomerate onto the film surface, P(GMA/MA-POSS) and PGMA/NH 2 -POSS films exhibit much more heterogeneous surfaces than PGMA/NH 2 -PDMS film, but the well-compatibility between epoxy matrix and MA-POSS has provided P(GMA/MA-POSS) film with much higher transmittance (98%) than PGMA/NH 2 -POSS film (24%), PGMA/NH 2 -PDMS film (27%) and traditional epoxy resin film (5%). The introduction of polysiloxane into epoxy matrix is confirmed to create hybrids with strong adhesive strength (526-1113N) and high thermos-stability (T g =262-282°C), especially the cage-structured P(GMA/MA-POSS) hybrid (1113N and 282°C), but the flexible PDMS improves PGMA/NH 2 -PDMS hybrid with much higher storage modulus (519MPa) than PGMA/NH 2 -POSS (271MPa), which suggests that PDMS is advantage in improving the film stiffness than POSS cages. However, cage-structured P(GMA/MA-POSS) and PGMA/NH 2 -POSS indicate higher permeability than PGMA/NH 2 -PDMS and traditional epoxy resin. Comparatively, the cage-structured P(GMA/MA-POSS) hybrid is the best coating in transparency, permeability, adhesive strength and thermostability, but linear-structured PGMA/NH 2 -PDMS hybrid behaviors the best coating in

Epitaxial-Growth-Induced Junction Welding of Silver Nanowire Network Electrodes.

PubMed

Kang, Hyungseok; Song, Sol-Ji; Sul, Young Eun; An, Byeong-Seon; Yin, Zhenxing; Choi, Yongsuk; Pu, Lyongsun; Yang, Cheol-Woong; Kim, Youn Sang; Cho, Sung Min; Kim, Jung-Gu; Cho, Jeong Ho

2018-05-22

In this study, we developed a roll-to-roll Ag electroplating process for metallic nanowire electrodes using a galvanostatic mode. Electroplating is a low-cost and facile method for deposition of metal onto a target surface with precise control of both the composition and the thickness. Metallic nanowire networks [silver nanowires (AgNWs) and copper nanowires (CuNWs)] coated onto a polyethylene terephthalate (PET) film were immersed directly in an electroplating bath containing AgNO 3 . Solvated silver ions (Ag + ions) were deposited onto the nanowire surface through application of a constant current via an external circuit between the nanowire networks (cathode) and a Ag plate (anode). The amount of electroplated Ag was systematically controlled by changing both the applied current density and the electroplating time, which enabled precise control of the sheet resistance and optical transmittance of the metallic nanowire networks. The optimized Ag-electroplated AgNW (Ag-AgNW) films exhibited a sheet resistance of ∼19 Ω/sq at an optical transmittance of 90% (550 nm). A transmission electron microscopy study confirmed that Ag grew epitaxially on the AgNW surface, but a polycrystalline Ag structure was formed on the CuNW surface. The Ag-electroplated metallic nanowire electrodes were successfully applied to various electronic devices such as organic light-emitting diodes, triboelectric nanogenerators, and a resistive touch panel. The proposed roll-to-roll Ag electroplating process provides a simple, low-cost, and scalable method for the fabrication of enhanced transparent conductive electrode materials for next-generation electronic devices.

Phenomenal transparency in achromatic checkerboards.

PubMed

Masin, S C

1999-04-01

The study explored the luminance relations that determine the occurrence of achromatic transparency in phenomenal surfaces on complex backgrounds. Let the luminances of the left and right parts of a transparent surface on a bipartite background and those of the left and right parts of the bipartite background be p and q and m and n, respectively. Metelli proposed that this surface looks transparent when the rule p < q if m < n (or p > q if m > n) is satisfied, and Masin and Fukuda that it looks transparent when the inclusion rule is satisfied, that is, when p epsilon (m, q) or q epsilon (p, n). These rules also apply to achromatic checkerboards formed by one checkerboard enclosed in another checkerboard. This study shows that only the inclusion rule correctly predicted the occurrence of transparency in these checkerboards.

Robot transparency, trust and utility

NASA Astrophysics Data System (ADS)

Wortham, Robert H.; Theodorou, Andreas

2017-07-01

As robot reasoning becomes more complex, debugging becomes increasingly hard based solely on observable behaviour, even for robot designers and technical specialists. Similarly, non-specialist users have difficulty creating useful mental models of robot reasoning from observations of robot behaviour. The EPSRC Principles of Robotics mandate that our artefacts should be transparent, but what does this mean in practice, and how does transparency affect both trust and utility? We investigate this relationship in the literature and find it to be complex, particularly in nonindustrial environments where, depending on the application and purpose of the robot, transparency may have a wider range of effects on trust and utility. We outline our programme of research to support our assertion that it is nevertheless possible to create transparent agents that are emotionally engaging despite having a transparent machine nature.

Polarized linewidth-controllable double-trapping electromagnetically induced transparency spectra in a resonant plasmon nanocavity

PubMed Central

Wang, Luojia; Gu, Ying; Chen, Hongyi; Zhang, Jia-Yu; Cui, Yiping; Gerardot, Brian D.; Gong, Qihuang

2013-01-01

Surface plasmons with ultrasmall optical mode volume and strong near field enhancement can be used to realize nanoscale light-matter interaction. Combining surface plasmons with the quantum system provides the possibility of nanoscale realization of important quantum optical phenomena, including the electromagnetically induced transparency (EIT), which has many applications in nonlinear quantum optics and quantum information processing. Here, using a custom-designed resonant plasmon nanocavity, we demonstrate polarized position-dependent linewidth-controllable EIT spectra at the nanoscale. We analytically obtain the double coherent population trapping conditions in a double-Λ quantum system with crossing damping, which give two transparent points in the EIT spectra. The linewidths of the three peaks are extremely sensitive to the level spacing of the excited states, the Rabi frequencies and detunings of pump fields, and the Purcell factors. In particular the linewidth of the central peak is exceptionally narrow. The hybrid system may have potential applications in ultra-compact plasmon-quantum devices. PMID:24096943

Static and dynamic microscopy of the chemical stability and aggregation state of silver nanowires in components of murine pulmonary surfactant

PubMed Central

Theodorou, Ioannis G.; Botelho, Danielle; Schwander, Stephan; Zhang, Junfeng (Jim); Chung, Kian Fan; Tetley, Teresa D.; Shaffer, Milo S. P.; Gow, Andrew; Ryan, Mary P.; Porter, Alexandra E.

2016-01-01

The increase of production volumes of silver nanowires (AgNWs) and of consumer products incorporating them, may lead to increased health risks from occupational and public exposures. There is currently limited information about the putative toxicity of AgNWs upon inhalation, and incomplete understanding of the properties that control their bioreactivity. The lung lining fluid (LLF), which contains phospholipids and surfactant proteins, represents a first contact site with the respiratory system. In this work, the impact of Dipalmitoylphosphatidylcholine (DPPC), Curosurf® and murine LLF on the stability of AgNWs was examined. Both the phospholipid and protein components of the LLF modified the dissolution kinetics of AgNWs, due to the formation of a lipid corona or aggregation of the AgNWs. Moreover, the hydrophilic, but neither the hydrophobic surfactant proteins nor the phospholipids, induced agglomeration of the AgNWs. Finally, the generation of a secondary population of nano-silver was observed and attributed to the reduction of Ag+ ions by the surface capping of the AgNWs. Our findings highlight that combinations of spatially resolved dynamic and static techniques are required to develop a holistic understanding of which parameters govern AgNW behavior at the point of exposure and to accurately predict their risks on human health and the environment. PMID:26061974

Photoinduced electron transfer pathways in hydrogen-evolving reduced graphene oxide-boosted hybrid nano-bio catalyst.

PubMed

Wang, Peng; Dimitrijevic, Nada M; Chang, Angela Y; Schaller, Richard D; Liu, Yuzi; Rajh, Tijana; Rozhkova, Elena A

2014-08-26

Photocatalytic production of clean hydrogen fuels using water and sunlight has attracted remarkable attention due to the increasing global energy demand. Natural and synthetic dyes can be utilized to sensitize semiconductors for solar energy transformation using visible light. In this study, reduced graphene oxide (rGO) and a membrane protein bacteriorhodopsin (bR) were employed as building modules to harness visible light by a Pt/TiO2 nanocatalyst. Introduction of the rGO boosts the nano-bio catalyst performance that results in hydrogen production rates of approximately 11.24 mmol of H2 (μmol protein)(-1) h(-1). Photoelectrochemical measurements show a 9-fold increase in photocurrent density when TiO2 electrodes were modified with rGO and bR. Electron paramagnetic resonance and transient absorption spectroscopy demonstrate an interfacial charge transfer from the photoexcited rGO to the semiconductor under visible light.

Organic/Inorganic Hybrid Polymer/Clay Nanocomposites

NASA Technical Reports Server (NTRS)

Park, Cheol; Connell, John W.; Smith, Joseph G., Jr.

2003-01-01

A novel class of polymer/clay nanocomposites has been invented in an attempt to develop transparent, lightweight, durable materials for a variety of aerospace applications. As their name suggests, polymer/ clay nanocomposites comprise organic/ inorganic hybrid polymer matrices containing platelet-shaped clay particles that have sizes of the order of a few nanometers thick and several hundred nanometers long. Partly because of their high aspect ratios and high surface areas, the clay particles, if properly dispersed in the polymer matrix at a loading level of 1 to 5 weight percent, impart unique combinations of physical and chemical properties that make these nanocomposites attractive for making films and coatings for a variety of industrial applications. Relative to the unmodified polymer, the polymer/ clay nanocomposites may exhibit improvements in strength, modulus, and toughness; tear, radiation, and fire resistance; and lower thermal expansion and permeability to gases while retaining a high degree of optical transparency.

CdS decorated rGO containing PVDF electrospun fiber based piezoelectric nanogenerator for mechanical energy harvesting application

NASA Astrophysics Data System (ADS)

Roy, Krittish; Mandal, Dipankar

2018-04-01

In this work, we demonstrate a simple and facile route ofcadmium sulfide (CdS) nanoparticle (NPs) grafted reduced graphene oxide (rGO) synthesis. It is found that a pinch (0.25 wt%) of as synthesisedCdS/rGOnanocompositecan induce more than 90% of electroactive phases in the electrospunpoly(vinylidene fluoride) (PVDF) nanofiber. Moreover, CdS/rGO nanocomposite doped PVDF nanofiber based nanogenerator (NG) can generate an output voltage of approximately 4 V upon repetitive finger imparting. Thus, the NG can be used as a mechanical energy harvester and power source for portable electronic and optoelectronic wearable devices.

Organic inorganic hybrid coating (poly(methyl methacrylate)/monodisperse silica)

NASA Astrophysics Data System (ADS)

Rubio, E.; Almaral, J.; Ramírez-Bon, R.; Castaño, V.; Rodríguez, V.

2005-04-01

Polymethylmethacrylate-silica hybrid coatings were prepared from methyl methacrylate and monodisperse colloidal silica prepared by the Stöber method. The surfaces of the spheres were successfully modified by chemical reaction with 3-(trimethoxysilyl) propyl methacrylate (TMSPM) to compatibilise the organic and inorganic components of the precursor solution mixture. The coatings were deposited by dip-coating on glass substrates. They result with good properties of homogeneity, optical transparence, hardness and adhesion.

Optically transparent semiconducting polymer nanonetwork for flexible and transparent electronics

PubMed Central

Yu, Kilho; Park, Byoungwook; Kim, Geunjin; Kim, Chang-Hyun; Park, Sungjun; Kim, Jehan; Jung, Suhyun; Jeong, Soyeong; Kwon, Sooncheol; Kang, Hongkyu; Kim, Junghwan; Yoon, Myung-Han; Lee, Kwanghee

2016-01-01

Simultaneously achieving high optical transparency and excellent charge mobility in semiconducting polymers has presented a challenge for the application of these materials in future “flexible” and “transparent” electronics (FTEs). Here, by blending only a small amount (∼15 wt %) of a diketopyrrolopyrrole-based semiconducting polymer (DPP2T) into an inert polystyrene (PS) matrix, we introduce a polymer blend system that demonstrates both high field-effect transistor (FET) mobility and excellent optical transparency that approaches 100%. We discover that in a PS matrix, DPP2T forms a web-like, continuously connected nanonetwork that spreads throughout the thin film and provides highly efficient 2D charge pathways through extended intrachain conjugation. The remarkable physical properties achieved using our approach enable us to develop prototype high-performance FTE devices, including colorless all-polymer FET arrays and fully transparent FET-integrated polymer light-emitting diodes. PMID:27911774

Optical modulation from an electro-optic polymer based hybrid Fabry-Perot etalon using transparent conducting oxides

NASA Astrophysics Data System (ADS)

Gan, Haiyong; Zhang, Hongxi; DeRose, Christopher T.; Norwood, Robert A.; Fallahi, Mahmoud; Luo, Jingdong; Jen, Alex K.-Y.; Liu, Boyang; Ho, Seng-Tiong; Peyghambarian, Nasser

2007-02-01

Fabry-Perot etalons using electro-optic (EO) organic materials can be used for devices such as tunable filters and spatial light modulators (SLM's) for wavelength division multiplexing (WDM) communication systems 1-5 and ultrafast imaging systems. For these applications the SLM's need to have: (i) low insertion loss, (ii) high speed operation, and (iii) large modulation depth with low drive voltage. Recently, there have been three developments which together can enhance the SLM performance to a higher level. First, low loss distributed Bragg reflector (DBR) mirrors are now used in SLM's to replace thin metal mirrors, resulting in reduced transmission loss, high reflectivity (>99%) and high finesse. Second, EO polymer materials have shown excellent properties for wide bandwidth optical modulation for information technology due to their fabrication flexibility, compatibility with high speed operation, and large EO coefficients at telecommunication wavelengths. For instance, the EO polymer AJL8/APC (AJL8: nonlinear optical chromophore, and APC: amorphous polycarbonate has recently been incorporated into waveguide modulators and achieved good performance for optical modulation. Finally, very low loss transparent conducting oxide (TCO) electrodes have drawn increasing attention for applications in optoelectronic devices. Here we will address how the low loss indium oxide (In IIO 3) electrodes with an absorption coefficient ~1000/cm and conductivity ~204 S/cm can help improve the modulation performance of EO polymer Fabry-Pérot étalons using the advanced electro-optic (EO) polymer material (AJL8/APC). A hybrid etalon structure with one highly conductive indium tin oxide (ITO) electrode outside the etalon cavity and one low-absorption In IIO 3 electrode inside etalon cavity has been demonstrated. High finesse (~234), improved effective applied voltage ratio (~0.25), and low insertion loss (~4 dB) have been obtained. A 10 dB isolation ratio and ~10% modulation depth at

78 FR 14149 - 2012 Fiscal Transparency Report

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-04

... DEPARTMENT OF STATE [Public Notice 8213] 2012 Fiscal Transparency Report AGENCY: Department of... Fiscal Transparency review process in its first annual Fiscal Transparency Report. This report describes... the standard. FY 2012 Fiscal Transparency Report The Department of State hereby presents the findings...

Three-Dimensional Printing Based Hybrid Manufacturing of Microfluidic Devices.

PubMed

Alapan, Yunus; Hasan, Muhammad Noman; Shen, Richang; Gurkan, Umut A

2015-05-01

Microfluidic platforms offer revolutionary and practical solutions to challenging problems in biology and medicine. Even though traditional micro/nanofabrication technologies expedited the emergence of the microfluidics field, recent advances in advanced additive manufacturing hold significant potential for single-step, stand-alone microfluidic device fabrication. One such technology, which holds a significant promise for next generation microsystem fabrication is three-dimensional (3D) printing. Presently, building 3D printed stand-alone microfluidic devices with fully embedded microchannels for applications in biology and medicine has the following challenges: (i) limitations in achievable design complexity, (ii) need for a wider variety of transparent materials, (iii) limited z-resolution, (iv) absence of extremely smooth surface finish, and (v) limitations in precision fabrication of hollow and void sections with extremely high surface area to volume ratio. We developed a new way to fabricate stand-alone microfluidic devices with integrated manifolds and embedded microchannels by utilizing a 3D printing and laser micromachined lamination based hybrid manufacturing approach. In this new fabrication method, we exploit the minimized fabrication steps enabled by 3D printing, and reduced assembly complexities facilitated by laser micromachined lamination method. The new hybrid fabrication method enables key features for advanced microfluidic system architecture: (i) increased design complexity in 3D, (ii) improved control over microflow behavior in all three directions and in multiple layers, (iii) transverse multilayer flow and precisely integrated flow distribution, and (iv) enhanced transparency for high resolution imaging and analysis. Hybrid manufacturing approaches hold great potential in advancing microfluidic device fabrication in terms of standardization, fast production, and user-independent manufacturing.

Biaxially stretchable supercapacitors based on the buckled hybrid fiber electrode array

NASA Astrophysics Data System (ADS)

Zhang, Nan; Zhou, Weiya; Zhang, Qiang; Luan, Pingshan; Cai, Le; Yang, Feng; Zhang, Xiao; Fan, Qingxia; Zhou, Wenbin; Xiao, Zhuojian; Gu, Xiaogang; Chen, Huiliang; Li, Kewei; Xiao, Shiqi; Wang, Yanchun; Liu, Huaping; Xie, Sishen

2015-07-01

In order to meet the growing need for smart bionic devices and epidermal electronic systems, biaxial stretchability is essential for energy storage units. Based on porous single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene) (SWCNT/PEDOT) hybrid fiber, we designed and fabricated a biaxially stretchable supercapacitor, which possesses a unique configuration of the parallel buckled hybrid fiber array. Owing to the reticulate SWCNT film and the improved fabrication technique, the hybrid fiber retained its porous architecture both outwardly and inwardly, manifesting a superior capacity of 215 F g-1. H3PO4-polyvinyl alcohol gel with an optimized component ratio was introduced as both binder and stretchable electrolyte, which contributed to the regularity and stability of the buckled fiber array. The buckled structure and the quasi one-dimensional character of the fibers endow the supercapacitor with 100% stretchability along all directions. In addition, the supercapacitor exhibited good transparency, as well as excellent electrochemical properties and stability after being stretched 5000 times.In order to meet the growing need for smart bionic devices and epidermal electronic systems, biaxial stretchability is essential for energy storage units. Based on porous single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene) (SWCNT/PEDOT) hybrid fiber, we designed and fabricated a biaxially stretchable supercapacitor, which possesses a unique configuration of the parallel buckled hybrid fiber array. Owing to the reticulate SWCNT film and the improved fabrication technique, the hybrid fiber retained its porous architecture both outwardly and inwardly, manifesting a superior capacity of 215 F g-1. H3PO4-polyvinyl alcohol gel with an optimized component ratio was introduced as both binder and stretchable electrolyte, which contributed to the regularity and stability of the buckled fiber array. The buckled structure and the quasi one-dimensional character of the

Transparent Armor Cost Benefit Study

DTIC Science & Technology

2008-04-01

2005 2006 UNCLASSIFIED UNCLASSIFIED 4/30/2008 4/17 2006 “Iraqi Pope Glass” 2004-2005 - GPK Recent HistoryEarly OIF Curb Wt: 10,300lbs GVW: 12,100lbs...UNCLASSIFIED UNCLASSIFIED 4/30/2008 5/17 Future Transparent Gun Shields Requirement: Upgrade GPKS with transparent armor for enhanced situational...awareness while maintaining soldier cover within armor envelope. AHI GS & GPK Upgraded Gunner Shield – Transparent Armored Gun Shield (TAGS

Transparent Armor Cost Benefit Study

DTIC Science & Technology

2006-10-30

added this cocoon to approximately 100 HMMWVs in Ramadi. 2006 “Iraqi Pope Glass” 2004-2005 - GPK Recent HistoryEarly OIF Curb Wt: 10,300lbs GVW...12,100lbs UNCLASSIFIED UNCLASSIFIED 10/30/2006 5/14 Future Transparent Gun Shields Requirement: Upgrade GPKS with transparent armor for enhanced...situational awareness while maintaining soldier cover within armor envelope. AHI GS & GPK Upgraded Gunner Shield – Transparent Armored Gun Shield (TAGS

Silver Nanowire Exposure Results in Internalization and Toxicity to Daphnia Magna

PubMed Central

Scanlan, Leona D.; Reed, Robert B.; Loguinov, Alexandre V.; Antczak, Philipp; Tagmount, Abderrahmane; Aloni, Shaul; Nowinski, Daniel Thomas; Luong, Pauline; Tran, Christine; Karunaratne, Nadeeka; Pham, Don; Lin, Xin Xin; Falciani, Francesco; Higgins, Chris P.; Ranville, James F.; Vulpe, Chris D.; Gilbert, Benjamin

2013-01-01

Nanowires (NWs), high-aspect-ratio nanomaterials, are increasingly used in technological materials and consumer products and may have toxicological characteristics distinct from nanoparticles. We carried out a comprehensive evaluation of the physico-chemical stability of four silver nanowires (AgNWs) of two sizes and coatings and their toxicity to Daphnia magna. Inorganic aluminum-doped silica coatings were less effective than organic poly(vinyl pyrrolidone) coatings at preventing silver oxidation or Ag+ release and underwent a significant morphological transformation within one-hour following addition to low ionic strength Daphnia growth media. All AgNWs were highly toxic to D. magna but less toxic than ionic silver. Toxicity varied as a function of AgNW dimension, coating and solution chemistry. Ag+ release in the media could not account for observed AgNW toxicity. Single-particle inductively coupled plasma mass spectrometry (spICPMS) distinguished and quantified dissolved and nanoparticulate silver in microliter-scale volumes of Daphnia magna hemolymph with a limit of detection of approximately 10 ppb. The silver levels within the hemolymph of Daphnia exposed to both Ag+ and AgNW met or exceeded the initial concentration in the growth medium, indicating effective accumulation during filter feeding. Silver-rich particles were the predominant form of silver in hemolymph following exposure to both AgNWs and Ag+. Scanning electron microscopy (SEM) imaging of dried hemolymph found both AgNWs and silver precipitates that were not present in the AgNW stock or the growth medium. Both organic and inorganic coatings on the AgNW were transformed during ingestion or absorption. Pathway, gene ontology and clustering analyses of gene expression response indicated effects of AgNWs distinct from ionic silver on Daphnia magna. PMID:24099093

APTS and rGO co-functionalized pyrenated fluorescent nanonets for representative vapor phase nitroaromatic explosive detection

NASA Astrophysics Data System (ADS)

Guo, Linjuan; Zu, Baiyi; Yang, Zheng; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

2014-01-01

For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives.For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective π-π interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives. Electronic supplementary information (ESI) available: Vapor pressure of TNT and its analogues, fluorescence quenching kinetics, fluorescence quenching efficiencies and additional SEM images. See DOI: 10.1039/c3nr04960d

Reduced graphene oxide and Ag wrapped TiO{sub 2} photocatalyst for enhanced visible light photocatalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leong, Kah Hon; Sim, Lan Ching; Jang, Min

2015-10-01

A well-organised reduced graphene oxide (RGO) and silver (Ag) wrapped TiO{sub 2} nano-hybrid was successfully achieved through a facile and easy route. The inherent characteristics of the synthesized RGO-Ag/TiO{sub 2} were revealed through crystalline phase, morphology, chemical composition, Raman scattering, UV-visible absorption, and photoluminescence analyses. The adopted synthesis route significantly controlled the uniform formation of silver nanoparticles and contributed for the absorption of light in the visible spectrum through localized surface plasmon resonance effects. The wrapped RGO nanosheets triggered the electron mobility and promoted visible light shift towards red spectrum. The accomplishment of synergised effect of RGO and Ag wellmore » degraded Bisphenol A under visible light irradiation with a removal efficiency of 61.9%.« less

In Vitro Dermal Safety Assessment of Silver Nanowires after Acute Exposure: Tissue vs. Cell Models

PubMed Central

Grichine, Alexei; Rachidi, Walid; Charlet, Laurent

2018-01-01

Silver nanowires (AgNW) are attractive materials that are anticipated to be incorporated into numerous consumer products such as textiles, touchscreen display, and medical devices that could be in direct contact with skin. There are very few studies on the cellular toxicity of AgNW and no studies that have specifically evaluated the potential toxicity from dermal exposure. To address this question, we investigated the dermal toxicity after acute exposure of polymer-coated AgNW with two sizes using two models, human primary keratinocytes and human reconstructed epidermis. In keratinocytes, AgNW are rapidly and massively internalized inside cells leading to dose-dependent cytotoxicity that was not due to Ag+ release. Analysing our data with different dose metrics, we propose that the number of NW is the most appropriate dose-metric for studies of AgNW toxicity. In reconstructed epidermis, the results of a standard in vitro skin irritation assay classified AgNW as non-irritant to skin and we found no evidence of penetration into the deeper layer of the epidermis. The findings show that healthy and intact epidermis provides an effective barrier for AgNW, although the study does not address potential transport through follicles or injured skin. The combined cell and tissue model approach used here is likely to provide an important methodology for assessing the risks for skin exposure to AgNW from consumer products. PMID:29641466

In Vitro Dermal Safety Assessment of Silver Nanowires after Acute Exposure: Tissue vs. Cell Models.

PubMed

Lehmann, Sylvia G; Gilbert, Benjamin; Maffeis, Thierry Gg; Grichine, Alexei; Pignot-Paintrand, Isabelle; Clavaguera, Simon; Rachidi, Walid; Seve, Michel; Charlet, Laurent

2018-04-11

Silver nanowires (AgNW) are attractive materials that are anticipated to be incorporated into numerous consumer products such as textiles, touchscreen display, and medical devices that could be in direct contact with skin. There are very few studies on the cellular toxicity of AgNW and no studies that have specifically evaluated the potential toxicity from dermal exposure. To address this question, we investigated the dermal toxicity after acute exposure of polymer-coated AgNW with two sizes using two models, human primary keratinocytes and human reconstructed epidermis. In keratinocytes, AgNW are rapidly and massively internalized inside cells leading to dose-dependent cytotoxicity that was not due to Ag⁺ release. Analysing our data with different dose metrics, we propose that the number of NW is the most appropriate dose-metric for studies of AgNW toxicity. In reconstructed epidermis, the results of a standard in vitro skin irritation assay classified AgNW as non-irritant to skin and we found no evidence of penetration into the deeper layer of the epidermis. The findings show that healthy and intact epidermis provides an effective barrier for AgNW, although the study does not address potential transport through follicles or injured skin. The combined cell and tissue model approach used here is likely to provide an important methodology for assessing the risks for skin exposure to AgNW from consumer products.

High-performance electrochemical mercury aptasensor based on synergistic amplification of Pt nanotube arrays and Fe3O4/rGO nanoprobes.

PubMed

Luo, Jingyi; Jiang, Danfeng; Liu, Tao; Peng, Jingmeng; Chu, Zhenyu; Jin, Wanqin

2018-05-01

In this work, a novel sandwich-type aptasensor was designed for the ultrasensitive recognition of trace mercury ions in water. Numerous oriented platinum nanotube arrays (PtNAs) were in-situ crystallized on a flexible electrode as a sensing interface, while thionine labelled Fe 3 O 4 /rGO nanocomposites as signal amplifiers. Both PtNAs/CF and nanocomposites were synthesized by easy hydrothermal processes. With their large surface area, it was favorable for electrochemical performance and immobilization of capture DNAs (cDNA) and report DNAs (rDNA). Upon the existence of Hg 2+ , partial linker DNAs were tightly bound with cDNAs through thymine-Hg 2+ -thymine pairing (T-Hg 2+ -T). Then rDNAs attached Fe 3 O 4 /rGO nanoprobes were fixed on the electrode through the match of remaining linker DNAs and rDNAs. Under the optimal conditions, the Hg 2+ aptasensor showed a synergistic amplification performance with a wide linear range from 0.1nM to 100nM, as well as a low detection limit of 30pM. Moreover, the as-prepared aptasensor also exhibited reliable performance for assay in real lake water samples. Copyright © 2017. Published by Elsevier B.V.

Transparent Armor Cost Benefit Study

DTIC Science & Technology

2007-03-06

Armored HMMWVs (M1114s) 2003 2005 2006 UNCLASSIFIED UNCLASSIFIED 3/6/2007 4/17 2006 “Iraqi Pope Glass” 2004-2005 - GPK Recent HistoryEarly OIF Curb Wt...10,300lbs GVW: 12,100lbs UNCLASSIFIED UNCLASSIFIED 3/6/2007 5/17 Future Transparent Gun Shields Requirement: Upgrade GPKS with transparent armor for...enhanced situational awareness while maintaining soldier cover within armor envelope. AHI GS & GPK Upgraded Gunner Shield – Transparent Armored Gun

High-performance metal mesh/graphene hybrid films using prime-location and metal-doped graphene.

PubMed

Min, Jung-Hong; Jeong, Woo-Lim; Kwak, Hoe-Min; Lee, Dong-Seon

2017-08-31

We introduce high-performance metal mesh/graphene hybrid transparent conductive layers (TCLs) using prime-location and metal-doped graphene in near-ultraviolet light-emitting diodes (NUV LEDs). Despite the transparency and sheet resistance values being similar for hybrid TCLs, there were huge differences in the NUV LEDs' electrical and optical properties depending on the location of the graphene layer. We achieved better physical stability and current spreading when the graphene layer was located beneath the metal mesh, in direct contact with the p-GaN layer. We further improved the contact properties by adding a very thin Au mesh between the thick Ag mesh and the graphene layer to produce a dual-layered metal mesh. The Au mesh effectively doped the graphene layer to create a p-type electrode. Using Raman spectra, work function variations, and the transfer length method (TLM), we verified the effect of doping the graphene layer after depositing a very thin metal layer on the graphene layers. From our results, we suggest that the nature of the contact is an important criterion for improving the electrical and optical performance of hybrid TCLs, and the method of doping graphene layers provides new opportunities for solving contact issues in other semiconductor devices.

Lutetium oxide-based transparent ceramic scintillators

DOEpatents

Seeley, Zachary; Cherepy, Nerine; Kuntz, Joshua; Payne, Stephen A.

2016-01-19

In one embodiment, a transparent ceramic of sintered nanoparticles includes gadolinium lutetium oxide doped with europium having a chemical composition (Lu.sub.1-xGd.sub.x).sub.2-YEu.sub.YO.sub.3, where X is any value within a range from about 0.05 to about 0.45 and Y is any value within a range from about 0.01 to about 0.2, and where the transparent ceramic exhibits a transparency characterized by a scatter coefficient of less than about 10%/cm. In another embodiment, a transparent ceramic scintillator of sintered nanoparticles, includes a body of sintered nanoparticles including gadolinium lutetium oxide doped with a rare earth activator (RE) having a chemical composition (Lu.sub.1-xGd.sub.x).sub.2-YRE.sub.YO.sub.3, where RE is selected from the group consisting of: Sm, Eu, Tb, and Dy, where the transparent ceramic exhibits a transparency characterized by a scatter coefficient of less than about 10%/cm.

Loaded Ce-Ag organic-inorganic hybrids and their antibacterial activity.

PubMed

Truffault, Laurianne; Rodrigues, Danilo Fernando; Salgado, Hérida Regida Nunes; Santilli, Celso Valentim; Pulcinelli, Sandra Helena

2016-11-01

There are requirements for surfaces with antibacterial properties in various technological fields. U-PEO hybrids with antibacterial properties were synthesized by the sol-gel process, incorporating combinations of cerium and silver salts at different silver molar fractions (0, 0.02, 0.05, 0.10, and 1) relative to the total amount of doped cations. The loaded hybrids were characterized by TGA, XRD, and Raman spectroscopy. Release tests were performed using UV-vis spectroscopy, and the antibacterial properties of the hybrids were studied in agar tests and turbidimetry assays. The nanostructural evolution of the hybrids during the release of the antibacterial agents was investigated by in situ SAXS. XRD results showed the presence of the AgCl crystalline phase in the loaded hybrids from a silver molar fraction of 0.05. Raman spectroscopy evidenced the interaction of silver cations with the polymeric part of the hybrid. SAXS results confirmed these interactions and showed that cerium species interacted with both organic and inorganic parts of the hybrids. The loaded U-PEO hybrids were found to release all the incorporated cerium in 1h, while the hybrid containing 100% of silver released only 78% of the incorporated silver. All the loaded hybrids displayed antibacterial activity against the Pseudomonas aeruginosa bacterium. The antibacterial activity was found to increase with silver molar fraction. Due to its high antibacterial activity and low silver molar fraction, the loaded hybrid with silver molar fraction of 0.10 seemed to be a good compromise between efficiency, esthetic transparency, and photostability. Copyright © 2016 Elsevier B.V. All rights reserved.

[Hybrid 3-D rendering of the thorax and surface-based virtual bronchoscopy in surgical and interventional therapy control].

PubMed

Seemann, M D; Gebicke, K; Luboldt, W; Albes, J M; Vollmar, J; Schäfer, J F; Beinert, T; Englmeier, K H; Bitzer, M; Claussen, C D

2001-07-01

The aim of this study was to demonstrate the possibilities of a hybrid rendering method, the combination of a color-coded surface and volume rendering method, with the feasibility of performing surface-based virtual endoscopy with different representation models in the operative and interventional therapy control of the chest. In 6 consecutive patients with partial lung resection (n = 2) and lung transplantation (n = 4) a thin-section spiral computed tomography of the chest was performed. The tracheobronchial system and the introduced metallic stents were visualized using a color-coded surface rendering method. The remaining thoracic structures were visualized using a volume rendering method. For virtual bronchoscopy, the tracheobronchial system was visualized using a triangle surface model, a shaded-surface model and a transparent shaded-surface model. The hybrid 3D visualization uses the advantages of both the color-coded surface and volume rendering methods and facilitates a clear representation of the tracheobronchial system and the complex topographical relationship of morphological and pathological changes without loss of diagnostic information. Performing virtual bronchoscopy with the transparent shaded-surface model facilitates a reasonable to optimal, simultaneous visualization and assessment of the surface structure of the tracheobronchial system and the surrounding mediastinal structures and lesions. Hybrid rendering relieve the morphological assessment of anatomical and pathological changes without the need for time-consuming detailed analysis and presentation of source images. Performing virtual bronchoscopy with a transparent shaded-surface model offers a promising alternative to flexible fiberoptic bronchoscopy.

Flexible Transparent Electronic Gas Sensors.

PubMed

Wang, Ting; Guo, Yunlong; Wan, Pengbo; Zhang, Han; Chen, Xiaodong; Sun, Xiaoming

2016-07-01

Flexible and transparent electronic gas sensors capable of real-time, sensitive, and selective analysis at room-temperature, have gained immense popularity in recent years for their potential to be integrated into various smart wearable electronics and display devices. Here, recent advances in flexible transparent sensors constructed from semiconducting oxides, carbon materials, conducting polymers, and their nanocomposites are presented. The sensing material selection, sensor device construction, and sensing mechanism of flexible transparent sensors are discussed in detail. The critical challenges and future development associated with flexible and transparent electronic gas sensors are presented. Smart wearable gas sensors are believed to have great potential in environmental monitoring and noninvasive health monitoring based on disease biomarkers in exhaled gas. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of (Co,Mn)3O4/rGO Composite for Lithium Ion Battery Anode by a One-Step Hydrothermal Process with H2O2 as Additive

PubMed Central

Li, Zuohua; Cui, Yanhui; Chen, Jun; Deng, Lianlin

2016-01-01

Binary transition metal oxides have been regarded as one of the most promising candidates for high-performance electrodes in energy storage devices, since they can offer high electrochemical activity and high capacity. Rational designing nanosized metal oxide/carbon composite architectures has been proven to be an effective way to improve the electrochemical performance. In this work, the (Co,Mn)3O4 spinel was synthesized and anchored on reduced graphene oxide (rGO) nanosheets using a facile and single hydrothermal step with H2O2 as additive, no further additional calcination required. Analysis showed that this method gives a mixed spinel, i.e. (Co,Mn)3O4, having 2+ and 3+ Co and Mn ions in both the octahedral and tetrahedral sites of the spinel structure, with a nanocubic morphology roughly 20 nm in size. The nanocubes are bound onto the rGO nanosheet uniformly in a single hydrothermal process, then the as-prepared (Co,Mn)3O4/rGO composite was characterized as the anode materials for Li-ion battery (LIB). It can deliver 1130.6 mAh g-1 at current density of 100 mA g-1 with 98% of coulombic efficiency after 140 cycles. At 1000 mA g-1, the capacity can still maintain 750 mAh g-1, demonstrating excellent rate capabilities. Therefore, the one-step process is a facile and promising method to fabricate metal oxide/rGO composite materials for energy storage applications. PMID:27788161

Fabrication of (Co,Mn)3O4/rGO Composite for Lithium Ion Battery Anode by a One-Step Hydrothermal Process with H2O2 as Additive.

PubMed

Li, Zuohua; Cui, Yanhui; Chen, Jun; Deng, Lianlin; Wu, Junwei

2016-01-01

Binary transition metal oxides have been regarded as one of the most promising candidates for high-performance electrodes in energy storage devices, since they can offer high electrochemical activity and high capacity. Rational designing nanosized metal oxide/carbon composite architectures has been proven to be an effective way to improve the electrochemical performance. In this work, the (Co,Mn)3O4 spinel was synthesized and anchored on reduced graphene oxide (rGO) nanosheets using a facile and single hydrothermal step with H2O2 as additive, no further additional calcination required. Analysis showed that this method gives a mixed spinel, i.e. (Co,Mn)3O4, having 2+ and 3+ Co and Mn ions in both the octahedral and tetrahedral sites of the spinel structure, with a nanocubic morphology roughly 20 nm in size. The nanocubes are bound onto the rGO nanosheet uniformly in a single hydrothermal process, then the as-prepared (Co,Mn)3O4/rGO composite was characterized as the anode materials for Li-ion battery (LIB). It can deliver 1130.6 mAh g-1 at current density of 100 mA g-1 with 98% of coulombic efficiency after 140 cycles. At 1000 mA g-1, the capacity can still maintain 750 mAh g-1, demonstrating excellent rate capabilities. Therefore, the one-step process is a facile and promising method to fabricate metal oxide/rGO composite materials for energy storage applications.

Electrical and optical properties of poly(3,4-ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate) and AuCl3-doped reduced graphene oxide/single-walled carbon nanotube films for ultraviolet light-emitting diodes.

PubMed

Lee, Byeong Ryong; Lee, Jae Hoon; Kim, Kyeong Heon; Kim, Hee-Dong; Kim, Tae Geun

2014-12-01

We report the effects of poly(3,4-ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate) ( PSS) and gold chloride (AuCl) co-doping on the electrical and optical properties of reduced graphene oxide (RGO)/single-walled carbon nanotube (SWNT) films fabricated by dipcoating methods. The RGO/SWNT films were doped with both AuCl3 dissolved in nitromethane and PSS hole injection layers by spin coating to improve their electrical properties by increasing the work function of the RGO/SWNT films, thereby reducing the Schottky barrier height between the RGO/SWNT and p-GaN films. As a result, we obtained a reduced sheet resistance of 851.9 Ω/Ω and a contact resistance of 1.97 x 10(-1) Ω x cm2, together with a high transmittance of 84.1% at 380 nm. The contact resistance of these films should be further reduced to fully utilize the feature of the electrode scheme proposed in this work, but the current result suggests its potential use as a transparent conductive electrode for ultraviolet light-emitting diodes.

Photoluminescence of Porous Silicon-Zinc Oxide Hybrid structures

NASA Astrophysics Data System (ADS)

Olenych, I. B.; Monastyrskii, L. S.; Luchechko, A. P.

2017-03-01

Arrays of ZnO nanostructures, which are optically transparent in the visible range, were grown on the surface of porous silicon by electrochemical deposition. Photoluminescence excitation and emission spectra of the obtained hybrid structures were investigated in 220-450 and 400-800 nm regions, respectively. It is established that multicolor emission is formed by combining the luminescence bands of porous silicon and zinc oxide. The possibility of controlling the photoluminescence spectra by changing the excitation energy is demonstrated. It is revealed that thermal annealing has an effect on the luminescent properties of porous silicon/zinc oxide hybrid structures. Thermal processing at 500°C leads to a sharp decrease of long-wavelength luminescence associated with porous silicon and to an increase of short-wavelength luminescence intensity related to zinc oxide.

Lines that induce phenomenal transparency.

PubMed

Grieco, Alba; Roncato, Sergio

2005-01-01

Three neighbouring opaque surfaces may appear split into two layers, one transparent and one opaque beneath, if an outline contour is drawn that encompasses two of them. The phenomenon was originally observed by Kanizsa [1955 Rivista di Psicologia 69 3-19; 1979 Organization in Vision: Essays on Gestalt Psychology (New York: Praeger)], for the case where an outline contour is drawn to encompass one of the two parts of a bicoloured figure and a portion of a background of lightest (or darkest) luminance. Preliminary observations revealed that the outline contour yields different effects: in addition to the stratification into layers described by Kanizsa, a second split, opposite in depth order, may occur when the outline contour is close in luminance to one of the three surfaces. An initial experiment was designed to investigate what conditions give rise to the two phenomenal transparencies: this led to the conclusion that an outline contour superimposed on an opaque surface causes this surface to emerge as a transparent layer when the luminances of the contour and the surface differ, in absolute value, by no more than 13.2 cd m(-2). We have named this phenomenon 'transparency of the intercepted surface', to distinguish it from the phenomenal transparency arising when the contour and surface are very different in luminance. When such a difference exists, the contour acts as a factor of surface definition and grouping: the portion of the homogeneous surface it bounds emerges as a fourth surface and groups with a nearby surface if there is one close in luminance. The transparency phenomena ('transparency of the contoured surface') perceived in this context conform to the constraints of Metelli's model, as demonstrated by a second experiment, designed to gather 'opacity' ratings of stimuli. The observer judgments conformed to the values predicted by Metelli's formula for perceived degree of transparency, alpha. The role of the outline contour in conveying figural and