Metal-insulator transition in nanocomposite VOx films formed by anodic electrodeposition

NASA Astrophysics Data System (ADS)

Tsui, Lok-kun; Hildebrand, Helga; Lu, Jiwei; Schmuki, Patrik; Zangari, Giovanni

2013-11-01

The ability to grow VO2 films by electrochemical methods would open a low-cost, easily scalable production route to a number of electronic devices. We have synthesized VOx films by anodic electrodeposition of V2O5, followed by partial reduction by annealing in Ar. The resulting films are heterogeneous, consisting of various metallic/oxide phases and including regions with VO2 stoichiometry. A gradual metal insulator transition with a nearly two order of magnitude change in film resistance is observed between room temperature and 140 °C. In addition, the films exhibit a temperature coefficient of resistance of ˜ -2.4%/ °C from 20 to 140 °C.

Ellipsometry of anodic film growth

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

Smith, C.G.

1978-08-01

An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen aremore » patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.« less

Growth behavior of anodic oxide formed by aluminum anodizing in glutaric and its derivative acid electrolytes

NASA Astrophysics Data System (ADS)

Nakajima, Daiki; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

2014-12-01

The growth behavior of anodic oxide films formed via anodizing in glutaric and its derivative acid solutions was investigated based on the acid dissociation constants of electrolytes. High-purity aluminum foils were anodized in glutaric, ketoglutaric, and acetonedicarboxylic acid solutions under various electrochemical conditions. A thin barrier anodic oxide film grew uniformly on the aluminum substrate by glutaric acid anodizing, and further anodizing caused the film to breakdown due to a high electric field. In contrast, an anodic porous alumina film with a submicrometer-scale cell diameter was successfully formed by ketoglutaric acid anodizing at 293 K. However, the increase and decrease in the temperature of the ketoglutaric acid resulted in non-uniform oxide growth and localized pitting corrosion of the aluminum substrate. An anodic porous alumina film could also be fabricated by acetonedicarboxylic acid anodizing due to the relatively low dissociation constants associated with the acid. Acid dissociation constants are an important factor for the fabrication of anodic porous alumina films.

Effect of various de-anodizing techniques on the surface stability of non-colored and colored nanoporous AAO films in acidic solution

NASA Astrophysics Data System (ADS)

Awad, Ahmed M.; Shehata, Omnia S.; Heakal, Fakiha El-Taib

2015-12-01

Anodic aluminum oxide (AAO) is well known as an important nanostructured material, and a useful template in the fabrication of nanostructures. Nanoporous anodic alumina (PAA) with high open porosity was prepared by adopting three de-anodizing regimes following the first anodizing step and preceding the second one. The de-anodizing methods include electrolytic etching (EE) and chemical etching using either phosphoric acid (PE) or sodium hydroxide (HE) solutions. Three of the obtained AAO samples were black colored by electrodeposition of copper nanoparticles in their pores. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques were used to characterize the electrochemical performance of the two sets of the prepared samples. In general, the data obtained in aggressive aerated 0.5 M HCl solution demonstrated dissimilar behavior for the three prepared samples despite that the second anodizing step was the same for all of them. The data indicated that the resistance and thickness of the inner barrier part of nano-PAA film, are the main controlling factors determining its stability. On the other hand, coloring the film decreased its stability due to the galvanic effect. The difference in the electrochemical behavior of the three colored samples was discussed based on the difference in both the pore size and thickness of the outer porous part of PAA film as supported by SEM, TEM and cross-sectional micrographs. These results can thus contribute for better engineering applications of nanoporous AAO.

Flexible Overoxidized Polypyrrole Films with Orderly Structure as High-Performance Anodes for Li- and Na-Ion Batteries.

PubMed

Yuan, Tao; Ruan, Jiafeng; Zhang, Weimin; Tan, Zhuopeng; Yang, Junhe; Ma, Zi-Feng; Zheng, Shiyou

2016-12-28

Flexible polypyrrole (PPy) films with highly ordered structures were fabricated by a novel vapor phase polymerization (VPP) process and used as the anode material in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The PPy films demonstrate excellent rate performance and cycling stability. At a charge/discharge rate of 1 C, the reversible capacities of the PPy film anode reach 284.9 and 177.4 mAh g -1 in LIBs and SIBs, respectively. Even at a charge/discharge rate of 20 C, the reversible capacity of the PPy film anode retains 54.0% and 52.9% of the capacity of 1 C in LIBs and SIBs, respectively. After 1000 electrochemical cycles at a rate of 10 C, there is no obvious capacity fading. The molecular structure and electrochemical behaviors of Li- and Na-ion doping and dedoping in the PPy films are investigated by XPS and ex situ XRD. It is believed that the PPy film electrodes in the overoxidized state can be reversibly charged and discharged through the doping and dedoping of lithium or sodium ions. Because of the self-adaptation of the doped ions, the ordered pyrrolic chain structure can realize a fast charge/discharge process. This result may substantially contribute to the progress of research into flexible polymer electrodes in various types of batteries.

Electrochemical cell with calcium anode

DOEpatents

Cooper, John F.; Hosmer, Pamela K.; Kelly, Benjamin E.

1979-01-01

An electrochemical cell comprising a calcium anode and a suitable cathode in an alkaline electrolyte consisting essentially of an aqueous solution of an hydroxide and a chloride. Specifically disclosed is a mechanically rechargeable calcium/air fuel cell with an aqueous NaOH/NaCl electrolyte.

Anode materials for electrochemical waste destruction

NASA Technical Reports Server (NTRS)

Molton, Peter M.; Clarke, Clayton

1990-01-01

Electrochemical Oxidation (ECO) offers promise as a low-temperature, atmospheric pressure method for safe destruction of hazardous organic chemical wastes in water. Anode materials tend to suffer corrosion in the intensely oxidizing environment of the ECO cell. There is a need for cheaper, more resistant materials. In this experiment, a system is described for testing anode materials, with examples of several common anodes such as stainless steel, graphite, and platinized titanium. The ECO system is simple and safe to operate and the experiment can easily be expanded in scope to study the effects of different solutions, temperatures, and organic materials.

Electrochemical membrane incinerator

DOEpatents

Johnson, Dennis C.; Houk, Linda L.; Feng, Jianren

2001-03-20

Electrochemical incineration of p-benzoquinone was evaluated as a model for the mineralization of carbon in toxic aromatic compounds. A Ti or Pt anode was coated with a film of the oxides of Ti, Ru, Sn and Sb. This quaternary metal oxide film was stable; elemental analysis of the electrolyzed solution indicated the concentration of these metal ions to be 3 .mu.g/L or less. The anode showed good reactivity for the electrochemical incineration of benzoquinone. The use of a dissolved salt matrix as the so-called "supporting electrolyte" was eliminated in favor of a solid-state electrolyte sandwiched between the anode and cathode.

Thin film buried anode battery

DOEpatents

Lee, Se-Hee [Lakewood, CO; Tracy, C Edwin [Golden, CO; Liu, Ping [Denver, CO

2009-12-15

A reverse configuration, lithium thin film battery (300) having a buried lithium anode layer (305) and process for making the same. The present invention is formed from a precursor composite structure (200) made by depositing electrolyte layer (204) onto substrate (201), followed by sequential depositions of cathode layer (203) and current collector (202) on the electrolyte layer. The precursor is subjected to an activation step, wherein a buried lithium anode layer (305) is formed via electroplating a lithium anode layer at the interface of substrate (201) and electrolyte film (204). The electroplating is accomplished by applying a current between anode current collector (201) and cathode current collector (202).

Anodic oxidation of commercially pure titanium for purification of polluted water

NASA Astrophysics Data System (ADS)

Benkafada, Faouzia; Kerdoud, Djahida; Bouchoucha, Ali

2018-05-01

Anodisation of pure titanium has been carried out in sulphuric acid solution at potentials ranging from 40 V to 5 days. We studied the parameters influencing the anodic deposition such as acid concentration and anodic periods. Anodic oxides thin films were characterized by X-ray diffraction, cyclic polarization and electrochemical impedance spectroscopy. The I-V curves and electrochemical impedance measurements were carried out in 0.1 N NaOH solution. The results indicated that although the thin films obtained by anodic oxidation are nonstoichiometric, they have an electric behaviour like n-type semiconducting material.

Nanotubular surface modification of metallic implants via electrochemical anodization technique.

PubMed

Wang, Lu-Ning; Jin, Ming; Zheng, Yudong; Guan, Yueping; Lu, Xin; Luo, Jing-Li

2014-01-01

Due to increased awareness and interest in the biomedical implant field as a result of an aging population, research in the field of implantable devices has grown rapidly in the last few decades. Among the biomedical implants, metallic implant materials have been widely used to replace disordered bony tissues in orthopedic and orthodontic surgeries. The clinical success of implants is closely related to their early osseointegration (ie, the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant), which relies heavily on the surface condition of the implant. Electrochemical techniques for modifying biomedical implants are relatively simple, cost-effective, and appropriate for implants with complex shapes. Recently, metal oxide nanotubular arrays via electrochemical anodization have become an attractive technique to build up on metallic implants to enhance the biocompatibility and bioactivity. This article will thoroughly review the relevance of electrochemical anodization techniques for the modification of metallic implant surfaces in nanoscale, and cover the electrochemical anodization techniques used in the development of the types of nanotubular/nanoporous modification achievable via electrochemical approaches, which hold tremendous potential for bio-implant applications. In vitro and in vivo studies using metallic oxide nanotubes are also presented, revealing the potential of nanotubes in biomedical applications. Finally, an outlook of future growth of research in metallic oxide nanotubular arrays is provided. This article will therefore provide researchers with an in-depth understanding of electrochemical anodization modification and provide guidance regarding the design and tuning of new materials to achieve a desired performance and reliable biocompatibility.

Nanotubular surface modification of metallic implants via electrochemical anodization technique

PubMed Central

Wang, Lu-Ning; Jin, Ming; Zheng, Yudong; Guan, Yueping; Lu, Xin; Luo, Jing-Li

2014-01-01

Due to increased awareness and interest in the biomedical implant field as a result of an aging population, research in the field of implantable devices has grown rapidly in the last few decades. Among the biomedical implants, metallic implant materials have been widely used to replace disordered bony tissues in orthopedic and orthodontic surgeries. The clinical success of implants is closely related to their early osseointegration (ie, the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant), which relies heavily on the surface condition of the implant. Electrochemical techniques for modifying biomedical implants are relatively simple, cost-effective, and appropriate for implants with complex shapes. Recently, metal oxide nanotubular arrays via electrochemical anodization have become an attractive technique to build up on metallic implants to enhance the biocompatibility and bioactivity. This article will thoroughly review the relevance of electrochemical anodization techniques for the modification of metallic implant surfaces in nanoscale, and cover the electrochemical anodization techniques used in the development of the types of nanotubular/nanoporous modification achievable via electrochemical approaches, which hold tremendous potential for bio-implant applications. In vitro and in vivo studies using metallic oxide nanotubes are also presented, revealing the potential of nanotubes in biomedical applications. Finally, an outlook of future growth of research in metallic oxide nanotubular arrays is provided. This article will therefore provide researchers with an in-depth understanding of electrochemical anodization modification and provide guidance regarding the design and tuning of new materials to achieve a desired performance and reliable biocompatibility. PMID:25258532

Electrodeposition and Capacitive Behavior of Films for Electrodes of Electrochemical Supercapacitors

NASA Astrophysics Data System (ADS)

Shi, C.; Zhitomirsky, I.

2010-03-01

Polypyrrole films were deposited by anodic electropolymerization on stainless steel substrates from aqueous pyrrole solutions containing sodium salicylate and tiron additives. The deposition yield was studied under galvanostatic conditions. The amount of the deposited material was varied by the variation of deposition time at a constant current density. SEM studies showed the formation of porous films with thicknesses in the range of 0-3 μm. Cyclic voltammetry data for the films tested in 0.5 M Na2SO4 solutions showed capacitive behavior and high specific capacitance (SC) in a voltage window of 0.9 V. The films prepared from pyrrole solutions containing tiron showed better capacitive behavior compared to the films prepared from the solutions containing sodium salicylate. A highest SC of 254 F g-1 was observed for the sample with a specific mass of 89 μg cm-2 at a scan rate of 2 mV s-1. The SC decreased with an increasing film thickness and scan rate. The results indicated that the polypyrrole films deposited on the stainless steel substrates by anodic electropolymerization can be used as electrodes for electrochemical supercapacitors (ES).

Electrodeposition and capacitive behavior of films for electrodes of electrochemical supercapacitors.

PubMed

Shi, C; Zhitomirsky, I

2010-01-08

Polypyrrole films were deposited by anodic electropolymerization on stainless steel substrates from aqueous pyrrole solutions containing sodium salicylate and tiron additives. The deposition yield was studied under galvanostatic conditions. The amount of the deposited material was varied by the variation of deposition time at a constant current density. SEM studies showed the formation of porous films with thicknesses in the range of 0-3 μm. Cyclic voltammetry data for the films tested in 0.5 M Na2SO4 solutions showed capacitive behavior and high specific capacitance (SC) in a voltage window of 0.9 V. The films prepared from pyrrole solutions containing tiron showed better capacitive behavior compared to the films prepared from the solutions containing sodium salicylate. A highest SC of 254 F g-1 was observed for the sample with a specific mass of 89 μg cm-2 at a scan rate of 2 mV s-1. The SC decreased with an increasing film thickness and scan rate. The results indicated that the polypyrrole films deposited on the stainless steel substrates by anodic electropolymerization can be used as electrodes for electrochemical supercapacitors (ES).

Electrodeposition and Capacitive Behavior of Films for Electrodes of Electrochemical Supercapacitors

PubMed Central

2010-01-01

Polypyrrole films were deposited by anodic electropolymerization on stainless steel substrates from aqueous pyrrole solutions containing sodium salicylate and tiron additives. The deposition yield was studied under galvanostatic conditions. The amount of the deposited material was varied by the variation of deposition time at a constant current density. SEM studies showed the formation of porous films with thicknesses in the range of 0–3 μm. Cyclic voltammetry data for the films tested in 0.5 M Na2SO4 solutions showed capacitive behavior and high specific capacitance (SC) in a voltage window of 0.9 V. The films prepared from pyrrole solutions containing tiron showed better capacitive behavior compared to the films prepared from the solutions containing sodium salicylate. A highest SC of 254 F g−1 was observed for the sample with a specific mass of 89 μg cm−2 at a scan rate of 2 mV s−1. The SC decreased with an increasing film thickness and scan rate. The results indicated that the polypyrrole films deposited on the stainless steel substrates by anodic electropolymerization can be used as electrodes for electrochemical supercapacitors (ES). PMID:20672082

Preparation and Characterization of Anode-Supported YSZ Thin Film Electrolyte by Co-Tape Casting and Co-Sintering Process

NASA Astrophysics Data System (ADS)

Liu, Q. L.; Fu, C. J.; Chan, S. H.; Pasciak, G.

2011-06-01

In this study, a co-tape casting and co-sintering process has been developed to prepare yttria-stabilized zirconia (YSZ) electrolyte films supported on Ni-YSZ anode substrates in order to substantially reduce the fabrication cost of solid oxide fuel cells (SOFC). Through proper control of the process, the anode/electrolyte bilayer structures with a size of 7.8cm × 7.8cm were achieved with good flatness. Scanning electron microscopy (SEM) observation indicated that the YSZ electrolyte film was about 16 μm in thickness, highly dense, crack free and well-bonded to the anode support. The electrochemical properties of the prepared anode-supported electrolyte film was evaluated in a button cell mode incorporating a (LaSr)MnO3-YSZ composite cathode. With humidified hydrogen as the fuel and stationary air as the oxidant, the cell demonstrated an open-circuit voltage of 1.081 V and a maximum power density of 1.01 W/cm2 at 800°C. The obtained results represent the important progress in the development of anode-supported intermediate temperature SOFC with reduced fabrication cost.

A Nanocrystalline Fe2O3 Film Anode Prepared by Pulsed Laser Deposition for Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Teng, Xiaoling; Qin, Youzhi; Wang, Xia; Li, Hongsen; Shang, Xiantao; Fan, Shuting; Li, Qiang; Xu, Jie; Cao, Derang; Li, Shandong

2018-02-01

Nanocrystalline Fe2O3 thin films are deposited directly on the conduct substrates by pulsed laser deposition as anode materials for lithium-ion batteries. We demonstrate the well-designed Fe2O3 film electrodes are capable of excellent high-rate performance (510 mAh g- 1 at high current density of 15,000 mA g- 1) and superior cycling stability (905 mAh g- 1 at 100 mA g- 1 after 200 cycles), which are among the best reported state-of-the-art Fe2O3 anode materials. The outstanding lithium storage performances of the as-synthesized nanocrystalline Fe2O3 film are attributed to the advanced nanostructured architecture, which not only provides fast kinetics by the shortened lithium-ion diffusion lengths but also prolongs cycling life by preventing nanosized Fe2O3 particle agglomeration. The electrochemical performance results suggest that this novel Fe2O3 thin film is a promising anode material for all-solid-state thin film batteries.

Ohmic resistance affects microbial community and electrochemical kinetics in a multi-anode microbial electrochemical cell

EPA Science Inventory

Multi-anode microbial electrochemical cells (MXCs) are considered as one of the most promising configurations for scale-up of MXCs, but fundamental understanding of anode kinetics governing current density is limited in the MXCs. In this study we first assessed microbial communi...

Use of Nanostructures in Fabrication of Large Scale Electrochemical Film

NASA Astrophysics Data System (ADS)

Chen, Chien Chon; Chen, Shih Hsun; Shyu, Sheang Wen; Hsieh, Sheng Jen

Control of electrochemical parameters when preparing small-scale samples for academic research is not difficult. In mass production environments, however, maintenance of constant current density and temperature become a critical issue. This article describes the design of several molds for large work pieces. These molds were designed to maintain constant current density and to facilitate the occurrence of electrochemical reactions in designated areas. Large-area thin films with fine nanostructure were successfully prepared using the designed electrochemical molds and containers. In addition, current density and temperature could be controlled well. This electrochemical system has been verified in many experimental operations, including etching of Al surfaces; electro-polishing of Al, Ti and stainless steel; and fabrication of anodic alumina oxide (AAO), Ti-TiO2 interference membrane, TiO2 nanotubes, AAO-TiO2 nanotubes, Ni nanowires and porous tungsten

Electrostatic spray deposition of porous SnO₂/graphene anode films and their enhanced lithium-storage properties.

PubMed

Jiang, Yinzhu; Yuan, Tianzhi; Sun, Wenping; Yan, Mi

2012-11-01

Porous SnO₂/graphene composite thin films are prepared as anodes for lithium ion batteries by the electrostatic spray deposition technique. Reticular-structured SnO₂ is formed on both the nickel foam substrate and the surface of graphene sheets according to the scanning electron microscopy (SEM) results. Such an assembly mode of graphene and SnO₂ is highly beneficial to the electrochemical performance improvement by increasing the electrical conductivity and releasing the volume change of the anode. The novel engineered anode possesses 2134.3 mA h g⁻¹ of initial discharge capacity and good capacity retention of 551.0 mA h g⁻¹ up to the 100th cycle at a current density of 200 mA g⁻¹. This anode also exhibits excellent rate capability, with a reversible capacity of 507.7 mA h g⁻¹ after 100 cycles at a current density of 800 mA g⁻¹. The results demonstrate that such a film-type hybrid anode shows great potential for application in high-energy lithium-ion batteries.

Biocompatibility of Mg Ion Doped Hydroxyapatite Films on Ti-6Al-4V Surface by Electrochemical Deposition.

PubMed

Lee, Kang; Choe, Han-Cheol

2016-02-01

In this study, we prepared magnesium (Mg) doped nano-phase hydroxyapatite (HAp) films on the TiO2 nano-network surface using electrochemical deposition method. Ti-6Al-4V ELI surface was anodized in 5 M NaOH solution at 0.3 A for 10 min. Nano-network TiO2 surface were formed by these anodization steps which acted as templates and anchorage for growth of the Mg doped HAp during subsequent pulsed electrochemical deposition process at 85 degrees C. The phase and morphologies of HAp deposits were influenced by the Mg ion concentration.

Electrochemical Treatment of Textile Dye Wastewater by Mild Steel Anode.

PubMed

Bhavya, J G; Rekha, H B; Murthy, Usha N

2014-04-01

This paper presents the results of the treatment of textile dye wastewater generated from a textile processing industry by electrochemical method. Experiments were conducted at current densities of 12, 24 and 48 A/m2 using mild steel as anode and cathode. During the various stages of electrolysis, parameters such as COD, color and BOD5 were determined in order to know the feasibility of electrochemical treatment. It was observed that increasing the electrolysis time and increased current density bring down the concentration of pollutants. Also COD removal rate and energy consumption during the electrolysis were calculated and presented in this paper. The present study proves the effectiveness of electrochemical treatment using MS as anode for TDW oxidation.

Fabrication of Self-Ordered Alumina Films with Large Interpore Distance by Janus Anodization in Citric Acid

NASA Astrophysics Data System (ADS)

Ma, Yingjun; Wen, Yihao; Li, Juan; Li, Yuxin; Zhang, Zhiying; Feng, Chenchen; Sun, Runguang

2016-12-01

Self-organized porous anodic alumina (PAA) formed by electrochemical anodization have become a fundamental tool to develop various functional nanomaterials. However, it is still a great challenge to break the interpore distance (Dint) limit (500 nm) by using current anodization technologies of mild anodization (MA) and hard anodization (HA). Here, we reported a new anodization mode named “Janus anodization” (JA) to controllably fabricate self-ordered PAA with large Dint at high voltage of 350-400 V. JA naturally occurs as anodizing Al foils in citric acid solution, which possessing both the characteristics of MA and HA. The process can be divided into two stages: I, slow pore nucleation stage similar to MA; II, unequilibrium self-organization process similar to HA. The as-prepared films had the highest modulus (7.0 GPa) and hardness (127.2 GPa) values compared with the alumina obtained by MA and HA. The optical studies showed that the black films have low reflectance (<10 %) in the wavelength range of 250-1500 nm and photoluminescence property. Dint can be tuned between 645-884 nm by controlling citric acid concentration or anodization voltage. JA is a potential technology to efficiently and controllably fabricate microstructured or hybrid micro- and nanostructured materials with novel properties.

Fabrication of Self-Ordered Alumina Films with Large Interpore Distance by Janus Anodization in Citric Acid

PubMed Central

Ma, Yingjun; Wen, Yihao; Li, Juan; Li, Yuxin; Zhang, Zhiying; Feng, Chenchen; Sun, Runguang

2016-01-01

Self-organized porous anodic alumina (PAA) formed by electrochemical anodization have become a fundamental tool to develop various functional nanomaterials. However, it is still a great challenge to break the interpore distance (Dint) limit (500 nm) by using current anodization technologies of mild anodization (MA) and hard anodization (HA). Here, we reported a new anodization mode named “Janus anodization” (JA) to controllably fabricate self-ordered PAA with large Dint at high voltage of 350–400 V. JA naturally occurs as anodizing Al foils in citric acid solution, which possessing both the characteristics of MA and HA. The process can be divided into two stages: I, slow pore nucleation stage similar to MA; II, unequilibrium self-organization process similar to HA. The as-prepared films had the highest modulus (7.0 GPa) and hardness (127.2 GPa) values compared with the alumina obtained by MA and HA. The optical studies showed that the black films have low reflectance (<10 %) in the wavelength range of 250–1500 nm and photoluminescence property. Dint can be tuned between 645–884 nm by controlling citric acid concentration or anodization voltage. JA is a potential technology to efficiently and controllably fabricate microstructured or hybrid micro- and nanostructured materials with novel properties. PMID:27958365

The effect of thin film morphology on the electrochemical performance of Cu-Sn anode for lithium rechargeable batteries.

PubMed

Polat, B D; Keleş, O

2014-05-01

We investigate the anode performance of non ordered and ordered nanostructured Cu-Sn thin films deposited via electron beam deposition technique. The ordered nanostructured Cu-Sn thin film having nano-porosities was fabricated using an oblique (co)deposition technique. Our results showed that the nano structured Cu-Sn thin film containing Cu-Sn nanorods had higher initial anodic capacity (790 mA h g(-)) than that of the non ordered thin film (330 mA h g(-)). But the capacity of the ordered nanostructured Cu-Sn thin film diminished after the first cycle and a steady state capacity value around 300 mA h g(-) is sustainable in following up to 80th cycle, which is attributed to the composition and morphology of the thin film. The presence of copper containing Sn nanorods leading to form nano-porosities as interstitial spaces among them, enhanced lithium ions movement within thin film and increased the thin film tolerance against the stress generated because of the drastic volume change occurred during lithiation-delithiation processes; hence, homogenously distributed porosities increased the cycle life of the thin film.

Non-aqueous electrolytes for electrochemical cells

DOEpatents

Zhang, Zhengcheng; Dong, Jian; Amine, Khalil

2016-06-14

An electrolyte electrochemical device includes an anodic material and an electrolyte, the electrolyte including an organosilicon solvent, a salt, and a hybrid additiving having a first and a second compound, the hybrid additive configured to form a solid electrolyte interphase film on the anodic material upon application of a potential to the electrochemical device.

Electrochemical impedance spectroscopy analysis of a thin polymer film-based micro-direct methanol fuel cell

NASA Astrophysics Data System (ADS)

Schulz, Tobias; Weinmüller, Christian; Nabavi, Majid; Poulikakos, Dimos

A single cell micro-direct methanol fuel cell (micro-DMFC) was investigated using electrochemical impedance spectroscopy. The electrodes consisted of thin, flexible polymer (SU8) film microchannel structures fabricated in-house using microfabrication techniques. AC impedance spectroscopy was used to separate contributions to the overall cell polarization from the anode, cathode and membrane. A clear distinction between the different electrochemical phenomena occurring in the micro-DMFC, especially the distinction between double layer charging and Faradaic reactions was shown. The effect of fuel flow rate, temperature, and anode flow channel structure on the impedance of the electrode reactions and membrane/electrode double layer charging were investigated. Analysis of impedance data revealed that the performance of the test cell was largely limited by the presence of intermediate carbon monoxide in the anode reaction. Higher temperatures increase cell performance by enabling intermediate CO to be oxidized at much higher rates. The results also revealed that serpentine anode flow microchannels show a lower tendency to intermediate CO coverage and a more stable cell behavior than parallel microchannels.

Dissecting anode swelling in commercial lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Ningxin; Tang, Huaqiong

2012-11-01

An innovative method is applied to investigate anode swelling during electrochemical processes in commercial lithium-ion batteries. Cathode surface is partially covered with a piece of paste to block the transportation of lithium ion from active material during charging/discharging, and the corresponding part on the anode film shows no formation of Li-graphite compounds during different electrochemical processes, which is confirmed by XRD analysis. The increases of anode thickness within and outside lithiated zone are measured, and defined as electrochemical swelling and physical swelling respectively. The microscopic lattice expansion of graphite due to lithiation process correlates to mesoscopic electrochemical swelling synchronically, while physical swelling tends to decrease steadily with time. The relationship among the microscopic stress due to lithium-ion intercalation, the mesoscopic stress resulting in anode swelling, and the macroscopic rippling of pouch cell after a large number of cycle test, is analyzed and correlated in terms of stress evolution across different scales, and suggestions for solving anode swelling are provided.

Anode for a secondary, high-temperature electrochemical cell

DOEpatents

Vissers, Donald R.; Tani, Benjamin S.

1976-01-01

A high-temperature, secondary electrochemical cell includes an anode containing lithium, an electrolyte containing lithium ions and a cathode containing a chalcogen material such as sulfur or a metallic sulfide. The anode includes a porous substrate formed of, for instance, a compacted mass of entangled metallic fibers providing interstitial crevices for receiving molten lithium metal. The surfaces of the interstitial crevices are provided with a coating of cobalt metal to enhance the retention of the molten lithium metal within the substrate.

Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

NASA Astrophysics Data System (ADS)

Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

2015-02-01

Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

Electrochemical Performance Estimation of Anodized AZ31B Magnesium Alloy as Function of Change in the Current Density

NASA Astrophysics Data System (ADS)

Girón, L.; Aperador, W.; Tirado, L.; Franco, F.; Caicedo, J. C.

2017-08-01

The anodized AZ31B magnesium alloys were synthesized via electrodeposition processes. The aim of this work was to determine the electrochemical behavior of magnesium alloys by using anodized alloys as a protective coating. The anodized alloys were characterized by x-ray diffraction, exhibiting the crystallography orientation for Mg and MgO phases. The x-ray photoelectron spectroscopy was used to determine the chemical composition of anodized magnesium alloys. By using electrochemical impedance spectroscopy and Tafel curves, it was possible to estimate the electrochemical behavior of anodized AZ31B magnesium alloys in Hank's balanced salt solution (HBSS). Scanning electron microscopy was performed to analyze chemical changes and morphological surface changes on anodized Mg alloys due to the reaction in HBSS/anodized magnesium surface interface. Electrochemical behavior in HBSS indicates that the coatings may be a promising material for biomedical industry.

Enhanced Cyclability of Lithium-Oxygen Batteries with Electrodes Protected by Surface Films Induced via In Situ Electrochemical Process

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

Liu, Bin; Xu, Wu; Tao, Jinhui

Although the rechargeable lithium-oxygen (Li-O2) batteries have extremely high theoretical specific energy, the practical application of these batteries is still limited by the instability of their carbon-based air-electrode, Li metal anode, and electrolytes towards reduced oxygen species. Here we demonstrate a simple one-step in-situ electrochemical pre-charging strategy to generate thin protective films on both carbon nanotubes (CNTs) air-electrode and Li metal anode simultaneously under an inert atmosphere. Li-O2 cells after such pre-treatment demonstrate significantly extended cycle life of 110 and 180 cycles under the capacity-limited protocol of 1000 mAh g-1 and 500 mAh g-1, respectively, which is far more thanmore » those without pre-treatment. The thin-films formed from decomposition of electrolyte during in-situ electrochemical pre-charging process in an inert environment can protect both CNTs air-electrode and Li metal anode prior to conventional Li-O2 discharge/charge cycling where reactive reduced oxygen species are formed. This work provides a new approach for protections of carbon-based air-electrode and Li metal anode in practical Li-O2 batteries, and may also be applied to other battery systems.« less

Spectroscopic And Electrochemical Studies Of Electrochromic Hydrated Nickel Oxide Films

NASA Astrophysics Data System (ADS)

Yu, P. C.; Nazri, G.; Lampert, C. M.

1986-09-01

The electrochrcrnic properties of hydrated nickel oxide thin films electrochemically deposited by anodization onto doped tin oxide-coated glass have been studied by transmittance measurements, cyclic voltammetry, Fourier-transform infrared spectroscopy, and ion-backscattering spectrometry. The spectral transmittance is reported for films switched in both the bleached and colored states. The photopic transmittance (Tp) can be switched from T (bleached) = 0.77 to T (colored) = 0.21, and the solar transmittance (Ts) can be switched from Ts(bleached) = 0.73 to TS (colored) = 0.35. Also reported is the near-infrared transmittance (TNIR)which was found to switch fran T N,IR (bleached) = 0.72 to TNIR (colored) = 0.55. The bleached condition is noted to have very low solar absorption in both the visible and solar regions. Ion-backscattering spectrometry was performed on the hydrated nickel oxide film, yielding a camposition of Ni01.0 (dehydrated) and a film thickness of 125 A. Cyclic voltammetry showed that, for films in the bleached or colored state, the reversible reaction is Ni(0H), = NiOOH + H+ + e . Voltammnetry also showed that the switching of the film is controlled by the diffusion or protons, where OH plays a role in the reaction mechanism. Analysis of the hydrated nickel-oxide thin films by Fourier-transform infrared spectroscopy revealed that both the bleached and colored states contain lattice water and hydroxyl groups. The surface hydroxyl groups play an important role in the coloration and bleaching of the anodically deposited nickel oxide thin films.

Ti/IrO2/SnO2 anode for electrochemical degradation of chlorpyrifos in water: optimization and degradation performances

NASA Astrophysics Data System (ADS)

Pathiraja, G. C.; Wijesingha, M. S.; Nanayakkara, N.

2017-05-01

Chlorpyrifos, a widely used organophosphate pesticide which can be found in surface water bodies, is harmful for human body. Thus, treating water contaminated with chlorpyrifos is important. In our previous studies, novel Ti/IrO2-SnO2 anode was successfully developed for electrochemical degradation of chlorpyrifos in chloride free water. In this study, optimization of previously developed Ti/IrO2-SnO2 anode for mineralization of chlorpyrifos was successfully performed through response surface methodology. During the optimization study, two-level factorial design was used to determine the optimal coating solutions concentration for developing the Ti/IrO2-SnO2 anode. Cyclic voltammetry and open circuit potential were performed to investigate the electrochemically active surface area and stability of these anodes. The response surface and contour plots show that 0.3 M of [Ir] and 7.5 mM of [Sn] coated electrode has both highest anodic charge and stability. Scanning Electron Microscopic (SEM) images show the evidence of having both compact and porous regions in the surface of the thin film, resulting larger surface area. Within 6 h, the best result for mineralization (55.56%) of chlorpyrifos was obtained with 0.3 M of [Ir] and 7.5 mM of [Sn] coated anode using Total organic Carbon (TOC) analyzer. Therefore, the optimum coating concentration was found as 0.3 M of [Ir] and 7.5 mM of [Sn]. It would require an energy consumption of 6 kWhm-3.

Metal-based anode for high performance bioelectrochemical systems through photo-electrochemical interaction

NASA Astrophysics Data System (ADS)

Liang, Yuxiang; Feng, Huajun; Shen, Dongsheng; Long, Yuyang; Li, Na; Zhou, Yuyang; Ying, Xianbin; Gu, Yuan; Wang, Yanfeng

2016-08-01

This paper introduces a novel composite anode that uses light to enhance current generation and accelerate biofilm formation in bioelectrochemical systems. The composite anode is composed of 316L stainless steel substrate and a nanostructured α-Fe2O3 photocatalyst (PSS). The electrode properties, current generation, and biofilm properties of the anode are investigated. In terms of photocurrent, the optimal deposition and heat-treatment times are found to be 30 min and 2 min, respectively, which result in a maximum photocurrent of 0.6 A m-2. The start-up time of the PSS is 1.2 days and the maximum current density is 2.8 A m-2, twice and 25 times that of unmodified anode, respectively. The current density of the PSS remains stable during 20 days of illumination. Confocal laser scanning microscope images show that the PSS could benefit biofilm formation, while electrochemical impedance spectroscopy indicates that the PSS reduce the charge-transfer resistance of the anode. Our findings show that photo-electrochemical interaction is a promising way to enhance the biocompatibility of metal anodes for bioelectrochemical systems.

Electrochemical performance and interfacial investigation on Si composite anode for lithium ion batteries in full cell

NASA Astrophysics Data System (ADS)

Shobukawa, Hitoshi; Alvarado, Judith; Yang, Yangyuchen; Meng, Ying Shirley

2017-08-01

Lithium ion batteries (LIBs) containing silicon (Si) as a negative electrode have gained much attention recently because they deliver high energy density. However, the commercialization of LIBs with Si anode is limited due to the unstable electrochemical performance associated with expansion and contraction during electrochemical cycling. This study investigates the electrochemical performance and degradation mechanism of a full cell containing Si composite anode and LiFePO4 (lithium iron phosphate (LFP)) cathode. Enhanced electrochemical cycling performance is observed when the full cell is cycled with fluoroethylene carbonate (FEC) additive compared to the standard electrolyte. To understand the improvement in the electrochemical performance, x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) are used. Based on the electrochemical behavior, FEC improves the reversibility of lithium ion diffusion into the solid electrolyte interphase (SEI) on the Si composite anode. Moreover, XPS analysis demonstrates that the SEI composition generated from the addition of FEC consists of a large amount of LiF and less carbonate species, which leads to better capacity retention over 40 cycles. The effective SEI successively yields more stable capacity retention and enhances the reversibility of lithium ion diffusion through the interphase of the Si anode, even at higher discharge rate. This study contributes to a basic comprehension of electrochemical performance and SEI formation of LIB full cells with a high loading Si composite anode.

Passive films on magnesium anodes in primary batteries

NASA Technical Reports Server (NTRS)

Ratnakumar, B. V.

1988-01-01

The characteristics of the passive films over Mg anodes, which essentially govern the voltage delay of the latter, have been determined nondestructively from an analysis of the transient and steady-state response of the electrode potential to low amplitude galvanostatic polarization under various experimental conditions viz., with different corrosion inhibitor coatings on Mg, after various periods of ageing of anode in solutions containing corrosion inhibitors, at various low temperatures etc. Using these parameters, the kinetics of film build-up or dissolution under these conditions have been monitored. The morphology of the anode film has been verified with scanning electron microscopy. Similar transients at low temperatures point out a steep rise in the film resistivity which is essentially responsible for the severe voltage delay. Finally, possible application of this technique in secondary Li batteries to improve cycling characteristics of the Li anode has been pointed out.

The anodizing behavior of aluminum in malonic acid solution and morphology of the anodic films

NASA Astrophysics Data System (ADS)

Ren, Jianjun; Zuo, Yu

2012-11-01

The anodizing behavior of aluminum in malonic acid solution and morphology of the anodic films were studied. The voltage-time response for galvanostatic anodization of aluminum in malonic acid solution exhibits a conventional three-stage feature but the formation voltage is much higher. With the increase of electrolyte concentration, the electrolyte viscosity increases simultaneously and the high viscosity decreases the film growth rate. With the concentration increase of the malonic acid electrolyte, the critical current density that initiates local "burning" on the sample surface decreases. For malonic acid anodization, the field-assisted dissolution on the oxide surface is relatively weak and the nucleation of pores is more difficult, which results in greater barrier layer thickness and larger cell dimension. The embryo of the porous structure of anodic film has been created within the linear region of the first transient stage, and the definite porous structure has been established before the end of the first transient stage. The self-ordering behavior of the porous film is influenced by the electrolyte concentration, film thickness and the applied current density. Great current density not only improves the cell arrangement order but also brings about larger cell dimension.

Improvement of corrosion resistance of NiTi sputtered thin films by anodization

NASA Astrophysics Data System (ADS)

Bayat, N.; Sanjabi, S.; Barber, Z. H.

2011-08-01

Anodization of sputtered NiTi thin films has been studied in 1 M acetic acid at 23 °C for different voltages from 2 to 10 V. The morphology and cross-sectional structures of the untreated and anodized surfaces were investigated by field emission scanning electron microscopy (FE-SEM). The results show that increasing anodization voltage leads to film surface roughening and unevenness. It can be seen that the thickness of the anodized layer formed on the NiTi surface is in the nanometer range. The corrosion resistance of anodized thin films was studied by potentiodynamic scan (PDS) and impedance spectroscopy (EIS) techniques in Hank's solution at 310 K (37 °C). It was shown that the corrosion resistance of the anodized film surface improved with increasing voltage to 6 V. Anodization of austenitic sputtered NiTi thin films has also been studied, in the same anodizing conditions, at 4 V. Comparison of anodized sputtered NiTi thin films with anodized austenitic shape memory films illustrate that the former are more corrosion resistant than the latter after 1 h immersion in Hank's solution, which is attributed to the higher grain boundary density to quickly form a stable and protective passive film.

The morphological study of porous silicon formed by electrochemical anodization method

NASA Astrophysics Data System (ADS)

Suryana, R.; Sandi, D. K.; Nakatsuka, O.

2018-03-01

Due to its good physical and chemical properties, porous silicon (PSi) is very attractive to study. In this research, PSi has been fabricated on n-type Si (100) by the electrochemical anodization method. The electrolyte solution used was a mixture of HF (40%), ethanol (99%) and aquadest with volume ratio of 1:1:2, respectively. It was anodized on Si(100) surface at different current densities of 10 mA/cm2 and 20 mA/cm2 with the anodization time at each current density for 10 min, 20 min, and 30 min. The Scanning Electron Microscope (SEM) images showed that the PSi surfaces have inhomogeneous sized pores in the range of 95.00 nm–1.46 μm. The PSi layers with current density and anodization time of 10 mA/cm2 (10 min), 10mA/cm2 (20 min), and 20mA/cm2 (10 min) have spherical shaped pores while the others have some uncommon (cross sectional) shaped pores on surfaces. It is considered that the cross sectional shaped maybe caused by unstable the current during the electrochemical anodization process.

Electrochemical properties of tin oxide anodes for sodium-ion batteries

NASA Astrophysics Data System (ADS)

Lu, Ying Ching; Ma, Chuze; Alvarado, Judith; Kidera, Takafumi; Dimov, Nikolay; Meng, Ying Shirley; Okada, Shigeto

2015-06-01

Few tin (Sn)-oxide based anode materials have been found to have large reversible capacity for both sodium (Na)-ion and lithium (Li)-ion batteries. Herein, we report the synthesis and electrochemical properties of Sn oxide-based anodes for sodium-ion batteries: SnO, SnO2, and SnO2/C. Among them, SnO is the most suitable anode for Na-ion batteries with less first cycle irreversibility, better cycle life, and lower charge transfer resistance. The energy storage mechanism of the above-mentioned Sn oxides was studied, which suggested that the conversion reaction of the Sn oxide anodes is reversible in Na-ion batteries. The better anode performance of SnO is attributed by the better conductivity.

Hybrid pulse anodization for the fabrication of porous anodic alumina films from commercial purity (99%) aluminum at room temperature.

PubMed

Chung, C K; Zhou, R X; Liu, T Y; Chang, W T

2009-02-04

Most porous anodic alumina (PAA) or anodic aluminum oxide (AAO) films are fabricated using the potentiostatic method from high-purity (99.999%) aluminum films at a low temperature of approximately 0-10 degrees C to avoid dissolution effects at room temperature (RT). In this study, we have demonstrated the fabrication of PAA film from commercial purity (99%) aluminum at RT using a hybrid pulse technique which combines pulse reverse and pulse voltages for the two-step anodization. The reaction mechanism is investigated by the real-time monitoring of current. A possible mechanism of hybrid pulse anodization is proposed for the formation of pronounced nanoporous film at RT. The structure and morphology of the anodic films were greatly influenced by the duration of anodization and the type of voltage. The best result was obtained by first applying pulse reverse voltage and then pulse voltage. The first pulse reverse anodization step was used to form new small cells and pre-texture concave aluminum as a self-assembled mask while the second pulse anodization step was for the resulting PAA film. The diameter of the nanopores in the arrays could reach 30-60 nm.

Suppression on allotropic transformation of Sn planar anode with enhanced electrochemical performance

NASA Astrophysics Data System (ADS)

Wang, Peng; Hu, Junhua; Cao, Guoqin; Zhang, Shilin; Zhang, Peng; Liang, Changhao; Wang, Zhuo; Shao, Guosheng

2018-03-01

Different configurations of Sn and C films were deposited and used as a planar anode for Li ion battery. The interplay of carbon layer with Sn as supporting and buffering, respectively, was revealed. The suppression on the allotropic transformation to α phase by a carbon layer results in a significantly improved capacity retention rate, which also avoids the crack of Sn film. As expected, a conductive carbon layer improves rating performance. However, a supporting carbon layer (SC) just contributes to the charge transfer process. A DFT approach was used to assess the allotropic transformation process. An additional barrier (∼0.86 eV) exits on the α-β diagram, which is responsible for the irreversibility of α phase back to β phase. An enhanced persistence of β phase in Sn/C anode contributes to cycling performance. A Li rich condition contributes to the stabilization of β-Sn, which is thermodynamically favored. A nano buffering carbon (BC) layer can evidently alleviate the side reaction on Sn surface, which in turn promotes the diffusion of Li ions in electrode and generates a Li rich condition. The direct contact of Sn with electrolyte leads to serious accumulation of α-Sn during cycling and results in a poor cycling performance. By the synergistic effect of BC and SC, a sandwich C/Sn/C structure demonstrates an enchantment in electrochemical behavior.

Effect of anode oxide films on glow discharge spatial structure

NASA Astrophysics Data System (ADS)

Gulamov, E. N.; Islamov, R. S.; Zabelin, Alexandre M.

1994-04-01

A self-consistent calculation of voltage fall on the anode film as a function of its resistance has been performed in the presence of anode current spots under elevated-pressure glow discharge in nitrogen and N2:He equals 1:1 mixture. It has been shown that resistance of anode oxide films in industrial lasers with continuous copper anode can reach the values when total suppression of anode current structures takes place.

Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

NASA Astrophysics Data System (ADS)

Maabong, Kelebogile; Machatine, Augusto G.; Hu, Yelin; Braun, Artur; Nambala, Fred J.; Diale, Mmantsae

2016-01-01

Hematite (α-Fe2O3) is a promising semiconductor as photoanode in solar hydrogen production from photoelectrolysis of water due to its appropriate band gap, low cost and high electrochemical stability in aqueous caustic electrolytes. Operation of such photoanode in a biased photoelectrochemical cell constitutes an anodization with consequent redox reactions at the electrode surface. α-Fe2O3 thin film photoanodes were prepared by simple and inexpensive dip coating method on fluorine doped tin oxide (FTO) glass substrate, annealed in air at 500 °C for 2 h, then electrochemically oxidized (anodized) in 1 M KOH at 500 mV for 1 min in dark and light conditions. Changes in structural properties and morphology of α-Fe2O3 nanoparticles films were investigated by XRD, Raman spectroscopy and a high resolution FE-SEM. The average grain size was observed to increase from 57 nm for pristine samples to 73 and 77 nm for anodized samples in dark and light respectively. Broadening and red shift in Raman spectra in anodized samples may be attributed to lattice expansion upon oxidation. The UV-visible measurements revealed enhanced absorption in the photoanodes after the treatment. The findings suggest that the anodization of the photoelectrode in a biased cell causes not only changes of the molecular structure at the surface, but also changes in the crystallographic structure which can be detected with x-ray diffractometry.

Electrochemical fabrication of capacitors

DOEpatents

Mansour, Azzam N.; Melendres, Carlos A.

1999-01-01

A film of nickel oxide is anodically deposited on a graphite sheet held in osition on an electrochemical cell during application of a positive electrode voltage to the graphite sheet while exposed to an electrolytic nickel oxide solution within a volumetrically variable chamber of the cell. An angularly orientated x-ray beam is admitted into the cell for transmission through the deposited nickel oxide film in order to obtain structural information while the film is subject to electrochemical and in-situ x-ray spectroscopy from which optimum film thickness, may be determined by comparative analysis for capacitor fabrication purposes.

High areal capacity, micrometer-scale amorphous Si film anode based on nanostructured Cu foil for Li-ion batteries

NASA Astrophysics Data System (ADS)

Si, Wenping; Sun, Xiaolei; Liu, Xianghong; Xi, Lixia; Jia, Yandong; Yan, Chenglin; Schmidt, Oliver G.

2014-12-01

We report a feasible design to fabricate micrometer-scale Si films deposited on nanostructured Cu foil as high areal capacity anodes for Li-ion batteries with excellent cycling performance. Nanostructured copper oxides are prepared by anodic oxidation of Cu foil in alkaline solution. The resultant copper oxide nanofibers function as matrix for thick Si films (1-2 μm) loading. Metallic Cu nanofibers are obtained by in-situ electrochemical reduction at low potentials, which work as electrical highways for fast electron transport and a reliable mechanical matrix to accommodate volume changes during lithium-silicon alloy/dealloy processes. The engineered thick Si film anode exhibit both high areal capacity (0.48 mAh cm-2 for 1 μm Si film and 0.6 mAh cm-2 for 2 μm Si film after 200 cycles at 0.225 mA cm-2) and excellent rate capability (0.52 mAh cm-2 at 1.05 mA cm-2 for 2 μm Si film). The 2 μm silicon film electrode is able to recover to the initial value of 1 mAh cm-2 when the current rate is set back to 0.15 mA cm-2 even after cycling at high current rates. The reported concept can be a general method for high-loading-film electrodes, which is industrial scalable and compatible with current battery manufacturing processes.

A Study on Sealing Process of Anodized Al Alloy Film

NASA Astrophysics Data System (ADS)

Tsujita, Takeshi; Sato, Hiroshi; Tsukahara, Sonoko; Ishikawa, Yuuichi

Since sealing is an important process to improve the corrosion resistance in practical application of anodized aluminum, we prepared anodic oxide films on A5052 alloy in an oxalic acid bath and a sulfuric acid bath, sealed them at various conditions, and analyzed them by scanning electron microscopy, acid-dissolution examination, admittance measurements and infrared spectroscopy. The pore radius of the oxalic acid anodized film was about 5 times larger than that of sulfuric acid anodized film, while the corrosion resistance of the former showed about 2 times higher value than the latter with the same sealed state and amount of hydroxide formed by sealing process of the former was 6 times larger than the latter, respectively. Steam sealing formed dense hydroxide and boiling water sealing formed big coral-like hydroxide, whereas the corrosion resistance of the film sealed by the former showed about 1.5 times higher value than that sealed by the latter, respectively. Thus microstructure of anodic oxide films and their surface morphology after sealing process clearly depended on their anodizing solution and the sealing condition and showed obvious relation to electric and corrosive properties.

A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes

NASA Astrophysics Data System (ADS)

Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

2015-12-01

Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well.

A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes.

PubMed

Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

2015-12-01

Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well.

Structural and electrochemical analysis of chemically synthesized microcubic architectured lead selenide thin films

NASA Astrophysics Data System (ADS)

Bhat, T. S.; Shinde, A. V.; Devan, R. S.; Teli, A. M.; Ma, Y. R.; Kim, J. H.; Patil, P. S.

2018-01-01

The present work deals with the synthesis of lead selenide (PbSe) thin films by simple and cost-effective chemical bath deposition method with variation in deposition time. The structural, morphological, and electrochemical properties of as-deposited thin films were examined using characterization techniques such as X-ray diffraction spectroscopy (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy. XRD reveals formation of rock salt phase cubic structured PbSe. FE-SEM images show the formation of microcubic structured morphology. The existence of the PbSe is confirmed from the XPS analysis. On the other hand, CV curves show four reaction peaks corresponding to oxidation [PbSe and Pb(OH)2] and reduction (PbO2 and Pb(OH)2) at the surface of PbSe thin films. The PbSe:2 sample deposited for 80 min. shows maximum specific capacitance of 454 ± 5 F g- 1 obtained at 0.25 mA cm- 2 current density. The maximum energy density of 69 Wh kg- 1 was showed by PbSe:2 electrode with a power density of 1077 W kg- 1. Furthermore, electrochemical impedance studies of PbSe:2 thin film show 80 ± 3% cycling stability even after 500 CV cycles. Such results show the importance of microcubic structured PbSe thin film as an anode in supercapacitor devices.

Effect of Different Binders on the Electrochemical Performance of Metal Oxide Anode for Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Wang, Rui; Feng, Lili; Yang, Wenrong; Zhang, Yinyin; Zhang, Yanli; Bai, Wei; Liu, Bo; Zhang, Wei; Chuan, Yongming; Zheng, Ziguang; Guan, Hongjin

2017-10-01

When testing the electrochemical performance of metal oxide anode for lithium-ion batteries (LIBs), binder played important role on the electrochemical performance. Which binder was more suitable for preparing transition metal oxides anodes of LIBs has not been systematically researched. Herein, five different binders such as polyvinylidene fluoride (PVDF) HSV900, PVDF 301F, PVDF Solvay5130, the mixture of styrene butadiene rubber and sodium carboxymethyl cellulose (SBR+CMC), and polyacrylonitrile (LA133) were studied to make anode electrodes (compared to the full battery). The electrochemical tests show that using SBR+CMC and LA133 binder which use water as solution were significantly better than PVDF. The SBR+CMC binder remarkably improve the bonding capacity, cycle stability, and rate performance of battery anode, and the capacity retention was about 87% after 50th cycle relative to the second cycle. SBR+CMC binder was more suitable for making transition metal oxides anodes of LIBs.

Active control of methanol carbonylation selectivity over Au/carbon anode by electrochemical potential.

PubMed

Funakawa, Akiyasu; Yamanaka, Ichiro; Otsuka, Kiyoshi

2005-05-12

Electrochemical oxidative carbonylation of methanol was studied over Au supported carbon anode in CO. The major carbonylation products were dimethyl oxalate (DMO) and dimethyl carbonate (DMC). The minor oxidation products were dimethoxy methane (DMM) and methyl formate (MF) from methanol and CO(2). Influences of various reaction conditions were studied on carbonylation activities and selectivities. The selectivities to DMO and DMC can be controlled by the electrochemical potential. Electrocatalysis of Au/carbon anode was studied by cyclic voltammetry (CV), stoichiometric reactions among Au(3+), methanol, and CO, and UV-vis spectra. The Au/carbon anode was characterized by XRD, SEM, and BE images before and after the carbonylation. These experimental facts strongly suggest that transition of oxidation states of Au affects changing of the carbonylation selectivities to DMO and DMC. Au(0) is the active species for the selective DMO formation by direct electrochemical carbonylation at low potentials (<+1.2 V (Ag/AgCl)). On the other hand, Au(3+) is the active spices for the selective DMC formation by indirect electrochemical carbonylation through Au(3+)/Au(+) redox at high potentials (>+1.3 V).

Electrochemically exfoliated graphene as a novel microwave susceptor: the ultrafast microwave-assisted synthesis of carbon-coated silicon-graphene film as a lithium-ion battery anode.

PubMed

Kim, Jong Min; Ko, Dongjin; Oh, Jiseop; Lee, Jeongyeon; Hwang, Taejin; Jeon, Youngmoo; Hooch Antink, Wytse; Piao, Yuanzhe

2017-10-19

Graphene nanocomposites have attracted much attention in many applications due to their superior properties. However, preparing graphene nanocomposites requires a time-consuming thermal treatment to reduce the graphene or synthesize nanomaterials, in most cases. We present an ultrafast synthesis of a carbon-coated silicon-graphene nanocomposite using a commercial microwave system. Electrochemically exfoliated graphene is used as a novel microwave susceptor to deliver efficient microwave energy conversion. Unlike graphene oxide, it does not require a time-consuming pre-thermal reduction or toxic chemical reduction to absorb microwave radiation efficiently. A carbon-coated silicon nanoparticle-electrochemically exfoliated graphene nanocomposite film was prepared by a few seconds' microwave irradiation. The sp 2 domains of graphene absorb microwave radiation and generate heat to simultaneously reduce the graphene and carbonize the polydopamine carbon precursor. The as-prepared N-doped carbon-coated silicon-graphene film was used as a lithium-ion battery anode. The N-doped carbon coating decreases the contact resistance between silicon nanoparticles and graphene provides a wide range conductive network. Consequently, it exhibited a reversible capacity of 1744 mA h g -1 at a current density of 0.1 A g -1 and 662 mA h g -1 at 1.0 A g -1 after 200 cycles. This method can potentially be a general approach to prepare various graphene nanocomposites in an extremely short time.

Biological capacitance studies of anodes in microbial fuel cells using electrochemical impedance spectroscopy.

PubMed

Lu, Zhihao; Girguis, Peter; Liang, Peng; Shi, Haifeng; Huang, Guangtuan; Cai, Lankun; Zhang, Lehua

2015-07-01

It is known that cell potential increases while anode resistance decreases during the start-up of microbial fuel cells (MFCs). Biological capacitance, defined as the apparent capacitance attributed to biological activity including biofilm production, plays a role in this phenomenon. In this research, electrochemical impedance spectroscopy was employed to study anode capacitance and resistance during the start-up period of MFCs so that the role of biological capacitance was revealed in electricity generation by MFCs. It was observed that the anode capacitance ranged from 3.29 to 120 mF which increased by 16.8% to 18-20 times over 10-12 days. Notably, lowering the temperature and arresting biological activity via fixation by 4% para formaldehyde resulted in the decrease of biological capacitance by 16.9 and 62.6%, indicating a negative correlation between anode capacitance and anode resistance of MFCs. Thus, biological capacitance of anode should play an important role in power generation by MFCs. We suggest that MFCs are not only biological reactors and/or electrochemical cells, but also biological capacitors, extending the vision on mechanism exploration of electron transfer, reactor structure design and electrode materials development of MFCs.

Method for transferring thermal energy and electrical current in thin-film electrochemical cells

DOEpatents

Rouillard, Roger [Beloeil, CA; Domroese, Michael K [South St. Paul, MN; Hoffman, Joseph A [Minneapolis, MN; Lindeman, David D [Hudson, WI; Noel, Joseph-Robert-Gaetan [St-Hubert, CA; Radewald, Vern E [Austin, TX; Ranger, Michel [Lachine, CA; Sudano, Anthony [Laval, CA; Trice, Jennifer L [Eagan, MN; Turgeon, Thomas A [Fridley, MN

2003-05-27

An improved electrochemical generator is disclosed. The electrochemical generator includes a thin-film electrochemical cell which is maintained in a state of compression through use of an internal or an external pressure apparatus. A thermal conductor, which is connected to at least one of the positive or negative contacts of the cell, conducts current into and out of the cell and also conducts thermal energy between the cell and thermally conductive, electrically resistive material disposed on a vessel wall adjacent the conductor. The thermally conductive, electrically resistive material may include an anodized coating or a thin sheet of a plastic, mineral-based material or conductive polymer material. The thermal conductor is fabricated to include a resilient portion which expands and contracts to maintain mechanical contact between the cell and the thermally conductive material in the presence of relative movement between the cell and the wall structure. The electrochemical generator may be disposed in a hermetically sealed housing.

Electrochemically exfoliated graphene anodes with enhanced biocurrent production in single-chamber air-breathing microbial fuel cells.

PubMed

Najafabadi, Amin Taheri; Ng, Norvin; Gyenge, Előd

2016-07-15

Microbial fuel cells (MFCs) present promising options for environmentally sustainable power generation especially in conjunction with waste water treatment. However, major challenges remain including low power density, difficult scale-up, and durability of the cell components. This study reports enhanced biocurrent production in a membrane-free MFC, using graphene microsheets (GNs) as anode and MnOx catalyzed air cathode. The GNs are produced by ionic liquid assisted simultaneous anodic and cathodic electrochemical exfoliation of iso-molded graphite electrodes. The GNs produced by anodic exfoliation increase the MFC peak power density by over 300% compared to plain carbon cloth (i.e., 2.85Wm(-2) vs 0.66Wm(-2), respectively), and by 90% compared to conventional carbon black (i.e., Vulcan XC-72) anode. These results exceed previously reported power densities for graphene-containing MFC anodes. The fuel cell polarization results are corroborated by electrochemical impedance spectroscopy indicating three times lower charge transfer resistance for the GN anode. Material characterizations suggest that the best performing GN samples were of relatively smaller size (~500nm), with higher levels of ionic liquid induced surface functionalization during the electrochemical exfoliation process. Copyright © 2016 Elsevier B.V. All rights reserved.

Nanostructured ZnO-TiO2 thin film oxide as anode material in electrooxidation of organic pollutants. Application to the removal of dye Amido black 10B from water.

PubMed

El-Kacemi, Sana; Zazou, Hicham; Oturan, Nihal; Dietze, Matthias; Hamdani, Mohamed; Es-Souni, Mohammed; Oturan, Mehmet A

2017-01-01

Electrochemical oxidative degradation of diazo dye Amido black 10B (AB10B) as model pollutant in water has been studied using nanostructured ZnO-TiO 2 thin films deposited on graphite felt (GrF) substrate as anode. The influence of various operating parameters, namely the current intensity, the nature and concentration of catalyst, the nature of electrode materials (anode/cathode), and the adsorption of dye and ambient light were investigated. It was found that the oxidative degradation of AB10B followed pseudo first-order kinetics. The optimal operating conditions for the degradation of 0.12 mM (74 mg L -1 ) dye concentration and mineralization of its aqueous solution were determined as GrF-ZnO-TiO 2 thin film anode, 100 mA current intensity, and 0.1 mM Fe 2+ (catalyst) concentration. Under these operating conditions, discoloration of AB10B solution was reached at 60 min while 6 h treatment needed for a mineralization degree of 91 %. Therefore, this study confirmed that the electrochemical process is effective for the degradation of AB10B in water using nanostructured ZnO-TiO 2 thin film anodes.

Solar Thermo-coupled Electrochemical Oxidation of Aniline in Wastewater for the Complete Mineralization Beyond an Anodic Passivation Film.

PubMed

Yuan, Dandan; Tian, Lei; Li, Zhida; Jiang, Hong; Yan, Chao; Dong, Jing; Wu, Hongjun; Wang, Baohui

2018-02-15

Herein, we report the solar thermal electrochemical process (STEP) aniline oxidation in wastewater for totally solving the two key obstacles of the huge energy consumption and passivation film in the electrochemical treatment. The process, fully driven by solar energy without input of any other energies, sustainably serves as an efficient thermoelectrochemical oxidation of aniline by the control of the thermochemical and electrochemical coordination. The thermocoupled electrochemical oxidation of aniline achieved a fast rate and high efficiency for the full minimization of aniline to CO 2 with the stability of the electrode and without formation of polyaniline (PAN) passivation film. A clear mechanism of aniline oxidation indicated a switching of the reactive pathway by the STEP process. Due to the coupling of solar thermochemistry and electrochemistry, the electrochemical current remained stable, significantly improving the oxidation efficiency and mineralization rate by apparently decreasing the electrolytic potential when applied with high temperature. The oxidation rate of aniline and chemical oxygen demand (COD) removal rate could be lifted up to 2.03 and 2.47 times magnification compared to conventional electrolysis, respectively. We demonstrate that solar-driven STEP processes are capable of completely mineralizing aniline with high utilization of solar energy. STEP aniline oxidation can be utilized as a green, sustainable water treatment.

Preparation of the porous cerium dioxide film by two-step anodization and heat treating method

NASA Astrophysics Data System (ADS)

Liu, Xiaozhen; Zhu, Bolun; Liu, Yuze; Wang, Shanshan; Chen, Jie; Wang, Xiaoyu

2017-12-01

The porous cerium dioxide films were prepared with cerium foils as raw materials by two-step anodization and heat treating method. The anodic cerium oxide films were heat treated in 25∼400°C respectively. The cerium dioxide films were characterized with X-ray diffraction (XRD), Fourier transform infrared (FTIR) techniques, energy-dispersive analyses of X-ray (EDAX) and scanning electron microcopy (SEM), respectively. The anodic cerium oxide film is composed of Ce(OH)3, CeO2 and Ce2O3. When the anodic cerium oxide films were heat treated in 300°C∼400°C for 2h, Ce(OH)3 and Ce2O3 in the anodic cerium oxide films may be converted to CeO2, and the heat treated anodic cerium oxide films are the cerium dioxide films. Water, ethylene glycol and CO2 are adsorbed in the anodic cerium oxide film. The adsorbing water, ethylene glycol and CO2 in the anodic cerium oxide film are removed at 300°C. The cerium dioxide film has strong absorption in the range of 1600∼4000cm-1. The structure of the cerium dioxide film is the porous.

Influence of anodizing conditions on generation of internal cracks in anodic porous tin oxide films grown in NaOH electrolyte

NASA Astrophysics Data System (ADS)

Zaraska, Leszek; Gawlak, Karolina; Gurgul, Magdalena; Dziurka, Magdalena; Nowak, Marlena; Gilek, Dominika; Sulka, Grzegorz D.

2018-05-01

Nanoporous tin oxide layers were synthesized via simple one-step anodic oxidation of a low-purity Sn foil (98.8%) in sodium hydroxide electrolyte. The process of pore formation at the early stage of anodization was discussed on the basis of concepts of oxygen bubble mould effect and viscous flow of oxide. The effect of anodizing conditions on the generation of internal cracks and fractures within the anodic film was investigated in detail. It was confirmed that crack-free tin oxide films can be obtained if the anodization is carried out at the potential of 4 V independently of the electrolyte concentration. On the other hand, the porous anodic film with a totally stacked internal morphology is obtained at the potential of 5 V in 0.1 M NaOH electrolyte. The generation of internal cracks and voids can be attributed to a much lower surface porosity and local trapping of O2 inside the pores of the oxide layer. However, increasing electrolyte concentration allows for obtaining less cracked porous films due to effective and uniform liberation of oxygen bubbles from the channels through completely open pore mouths. Furthermore, it was confirmed that uniformity of the anodic tin oxide layers can be significantly improved by vigorous electrolyte stirring. Finally, we observed that the addition of ethanol to the electrolyte can reduce anodic current density and the oxide growth rate. In consequence, less cracked anodic film can be formed even at the potential of 6 V. The generation of oxygen at the pore bottoms, together with the open pore mouths were found to be critical factors responsible for the anodic formation of crack-free porous tin oxide films.

The anodic surface film and hydrogen evolution on Mg

DOE PAGES

Song, Guang -Ling; Unocic, Kinga A.

2015-06-04

This paper clarifies that the inner and outer layers of the anodic film consist of a nano/micro-porous MgO+Mg(OH) 2 mixture. The film becomes thicker and more porous with increasing potential. It can rupture when potential is too positive in a non-corrosive Mg(OH) 2 solution. Hydrogen evolution becomes more intensive as polarization potential increases, particularly when the potential at the film-covered Mg surface is close to or more positive than the hydrogen equilibrium potential, suggesting that an “anodic hydrogen evolution” (AHE) reaction occurs on the substrate Mg in film pores, and the significantly intensified AHE causes film rupture at high potential.

Doping profile measurements in silicon using terahertz time domain spectroscopy (THz-TDS) via electrochemical anodic oxidation

NASA Astrophysics Data System (ADS)

Tulsyan, Gaurav

film are invisible to the terahertz probe this anodization step very effectively removes a 'thin slice' from the doping profile to be mapped. By iterating between anodization and terahertz measurements that detect only the 'remaining' non-oxidized portion of the doping profile one can re-construct the doping profile with significantly higher precision compared to what is possible by only a single non-destructive measurement of the un-anodized profile as used in the non-destructive version of our technique. In this MS thesis we explore all aspects of this anodization based variation of doping profile mapping using free space terahertz pulses. This includes a study of silicon dioxide thin film growth using a room temperature electrochemical oxidation process. Etching procedures providing the option to remove between successive anodization and terahertz measurement steps. THz-TDS measurements of successively anodized profiles will be compared with sheet resistance and SIMS measurements to benchmark and improve the new technique.

Gold-coated silicon nanowire-graphene core-shell composite film as a polymer binder-free anode for rechargeable lithium-ion batteries

NASA Astrophysics Data System (ADS)

Kim, Han-Jung; Lee, Sang Eon; Lee, Jihye; Jung, Joo-Yun; Lee, Eung-Sug; Choi, Jun-Hyuk; Jung, Jun-Ho; Oh, Minsub; Hyun, Seungmin; Choi, Dae-Geun

2014-07-01

We designed and fabricated a gold (Au)-coated silicon nanowires/graphene (Au-SiNWs/G) hybrid composite as a polymer binder-free anode for rechargeable lithium-ion batteries (LIBs). A large amount of SiNWs for LIB anode materials can be prepared by metal-assisted chemical etching (MaCE) process. The Au-SiNWs/G composite film on current collector was obtained by vacuum filtration using an anodic aluminum oxide (AAO) membrane and hot pressing method. Our experimental results show that the Au-SiNWs/G composite has a stable reversible capacity of about 1520 mA h/g which was maintained for 20 cycles. The Au-SiNWs/G composite anode showed much better cycling performance than SiNWs/polyvinylidene fluoride (PVDF)/Super-P, SiNWs/G composite, and pure SiNWs anodes. The improved electrochemical properties of the Au-SiNWs/G composite anode material is mainly ascribed to the composite's porous network structure.

Preparation of RuO2-TiO2/Nano-graphite composite anode for electrochemical degradation of ceftriaxone sodium.

PubMed

Li, Dong; Guo, Xiaolei; Song, Haoran; Sun, Tianyi; Wan, Jiafeng

2018-06-05

Graphite-like material is widely used for preparing various electrodes for wastewater treatment. To enhance the electrochemical degradation efficiency of Nano-graphite (Nano-G) anode, RuO 2 -TiO 2 /Nano-G composite anode was prepared through the sol-gel method and hot-press technology. RuO 2 -TiO 2 /Nano-G composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N 2 adsorption-desorption. Results showed that RuO 2 , TiO 2 and Nano-G were composited successfully, and RuO 2 and TiO 2 nanoparticles were distributed uniformly on the surface of Nano-G sheet. Specific surface area of RuO 2 -TiO 2 /Nano-G composite was higher than that of TiO 2 /Nano-G composite and Nano-G. Electrochemical performances of RuO 2 -TiO 2 /Nano-G anode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy. RuO 2 -TiO 2 /Nano-G anode was applied to electrochemical degradation of ceftriaxone. The generation of hydroxyl radical (OH) was measured. Results demonstrated that RuO 2 -TiO 2 /Nano-G anode displayed enhanced electrochemical degradation efficiency towards ceftriaxone and yield of OH, which is derived from the synergetic effect between RuO 2 , TiO 2 and Nano-G, which enhance the specific surface area, improve the electrochemical oxidation activity and lower the charge transfer resistance. Besides, the possible degradation intermediates and pathways of ceftriaxone sodium were identified. This study may provide a viable and promising prospect for RuO 2 -TiO 2 /Nano-G anode towards effective electrochemical degradation of antibiotics from wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

Fabrication and electrochemical performance of a stable, anode supported thin BaCe0.4Zr0.4Y0.2O3-δ electrolyte Protonic Ceramic Fuel Cell

NASA Astrophysics Data System (ADS)

Nasani, Narendar; Ramasamy, Devaraj; Mikhalev, Sergey; Kovalevsky, Andrei V.; Fagg, Duncan P.

2015-03-01

The present work deals with the fabrication and electrochemical characterisation of a potential protonic ceramic fuel cell based on a Ni-BaZr0.85Y0.15O3-δ anode supported thin film proton conducting BaCe0.4Zr0.4Y0.2O3-δ electrolyte with a Pr2NiO4+δ cathode. Anode and electrolyte materials were prepared by an acetate-H2O2 combustion method. A thin (∼5 μm), dense and crack free BaCe0.4Zr0.4Y0.2O3-δ electrolyte film was successfully obtained on a porous anode support by spin coating and firing at 1450 °C. Maximum power densities of 234, 158, 102 and 63 mW cm-2 at 700, 650, 600 and 550 °C, respectively were achieved for the Ni-BaZr0.85Y0.15O3-δ/BaCe0.4Zr0.4Y0.2O3-δ/Pr2NiO4+δ single cell under fuel cell testing conditions. Electrode polarisation resistance was assessed at open circuit conditions by use of electrochemical impedance spectroscopy (EIS) and is shown to dominate the area specific resistance at low temperatures. Postmortem analysis by scanning electron microscopy (SEM), reveals that no delamination occurs at anode/electrolyte or electrolyte/cathode interfaces upon cell operation.

Type I clathrates as novel silicon anodes: An electrochemical and structural investigation

DOE PAGES

Li, Ying; Raghavan, Rahul; Wagner, Nicholas A.; ...

2015-05-05

In this study, silicon clathrates contain cage-like structures that can encapsulate various guest atoms or molecules. Here we present an electrochemical evaluation of type I silicon clathrates based on Ba 8Al ySi 46-y for the anode material in lithium-ion batteries. Post-cycling characterization with NMR and XRD show no discernible structural or volume changes even after electrochemical insertion of 44 Li into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from larger volume changes. The lithiation/delithiation processes are proposed to occur in single phase reactions at approximately 0.2more » and 0.4 V vs. Li/Li +, respectively, distinct from other diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g -1 at a 5 mA g -1 rate were observed for silicon clathrate with composition Ba 8Al 8.54S i37.46, corresponding to Li:Si of 1.18:1. The results show that silicon clathrates could be promising durable anodes for lithium-ion batteries.« less

Type I clathrates as novel silicon anodes: An electrochemical and structural investigation

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

Li, Ying; Raghavan, Rahul; Wagner, Nicholas A.

In this study, silicon clathrates contain cage-like structures that can encapsulate various guest atoms or molecules. Here we present an electrochemical evaluation of type I silicon clathrates based on Ba 8Al ySi 46-y for the anode material in lithium-ion batteries. Post-cycling characterization with NMR and XRD show no discernible structural or volume changes even after electrochemical insertion of 44 Li into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from larger volume changes. The lithiation/delithiation processes are proposed to occur in single phase reactions at approximately 0.2more » and 0.4 V vs. Li/Li +, respectively, distinct from other diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g -1 at a 5 mA g -1 rate were observed for silicon clathrate with composition Ba 8Al 8.54S i37.46, corresponding to Li:Si of 1.18:1. The results show that silicon clathrates could be promising durable anodes for lithium-ion batteries.« less

Electrochemical cell stack assembly

DOEpatents

Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

2010-06-22

Multiple stacks of tubular electrochemical cells having a dense electrolyte disposed between an anode and a cathode preferably deposited as thin films arranged in parallel on stamped conductive interconnect sheets or ferrules. The stack allows one or more electrochemical cell to malfunction without disabling the entire stack. Stack efficiency is enhanced through simplified gas manifolding, gas recycling, reduced operating temperature and improved heat distribution.

Mechanistic Analysis of Mechano-Electrochemical Interaction in Silicon Electrodes with Surface Film

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

Verma, Ankit; Mukherjee, Partha P.

2017-11-17

High-capacity anode materials for lithium-ion batteries, such as silicon, are prone to large volume change during lithiation/delithiation which may cause particle cracking and disintegration, thereby resulting in severe capacity fade and reduction in cycle life. In this work, a stochastic analysis is presented in order to understand the mechano-electrochemical interaction in silicon active particles along with a surface film during cycling. Amorphous silicon particles exhibiting single-phase lithiation incur lower amount of cracking as compared to crystalline silicon particles exhibiting two-phase lithiation for the same degree of volumetric expansion. Rupture of the brittle surface film is observed for both amorphous andmore » crystalline silicon particles and is attributed to the large volumetric expansion of the silicon active particle with lithiation. The mechanical property of the surface film plays an important role in determining the amount of degradation in the particle/film assembly. A strategy to ameliorate particle cracking in silicon active particles is proposed.« less

Electrodeposition of polymer electrolyte in nanostructured electrodes for enhanced electrochemical performance of thin-film Li-ion microbatteries

NASA Astrophysics Data System (ADS)

Salian, Girish D.; Lebouin, Chrystelle; Demoulin, A.; Lepihin, M. S.; Maria, S.; Galeyeva, A. K.; Kurbatov, A. P.; Djenizian, Thierry

2017-02-01

We report that electrodeposition of polymer electrolyte in nanostructured electrodes has a strong influence on the electrochemical properties of thin-film Li-ion microbatteries. Electropolymerization of PMMA-PEG (polymethyl methacrylate-polyethylene glycol) was carried out on both the anode (self-supported titania nanotubes) and the cathode (porous LiNi0.5Mn1.5O4) by cyclic voltammetry and the resulting electrode-electrolyte interface was examined by scanning electron microscopy. The electrochemical characterizations performed by galvanostatic experiments reveal that the capacity values obtained at different C-rates are doubled when the electrodes are completely filled by the polymer electrolyte.

The optical and electrochemical properties of electrochromic films: WO3+xV2O5

NASA Astrophysics Data System (ADS)

Li, Zhuying; Liu, Hui; Liu, Ye; Yang, Shaohong; Liu, Yan; Wang, Chong

2010-05-01

Since Deb's experiment in 1973 on the electrochromic effect, transmissive electrochromic films exhibit outstanding potential as energy efficient window controls which allow dynamic control of the solar energy transmission. These films with non-volatile memory, once in the coloured state, remain in the same state even after removal of the field. The optical and electrochemical properties of electrochromic films using magnetron sputter deposition tungsten oxide thin films and vanadium oxide doped tungsten-vanadium oxide thin films on ITO coated glass were investigated. From the UV region of the transmittance spectra, the optical band gap energy from the fundamental absorption edge can be determined. And the Cyclic voltammograms of these thin films in 1 mol LiClO4 propylene carbonate electrolyte (LIPC) were measured and analysed. The anode electrochromic V2O5 doped cathode electrochromic WO3 could make films colour changing while the transmittance of films keeped invariance. These performance characteristics make tungstenvanadium oxide colour changeably thin films are suitable for electrochromic windows applications.

Fundamental Investigation of Si Anode in Li-Ion Cells

NASA Technical Reports Server (NTRS)

Wu, James J.; Bennett, William R.

2012-01-01

Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is approximately 10 times of graphite and it is an abundant element on earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of Si anode during the first cycle, the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes.

An Enzyme Switch Employing Direct Electrochemical Communication between Horseradish Peroxidase and a Poly(aniline) Film.

PubMed

Bartlett, P N; Birkin, P R; Wang, J H; Palmisano, F; De Benedetto, G

1998-09-01

An enzyme switch, or microelectrochemical enzyme transistor, responsive to hydrogen peroxide was made by connecting two carbon band electrodes (∼10 μm wide, 4.5 mm long separated by a 20-μm gap) with an anodically grown film of poly(aniline). Horseradish peroxidase (EC 1.11.1.7) was either adsorbed onto the poly(aniline) film or immobilized in an insulating poly(1,2-diaminobenzene) polymer grown electrochemically on top of the poly(aniline) film to complete the device. In the completed device, the conductivity of the poly(aniline) film changes from conducting (between - 0.05 and + 0.3 V vs SCE at pH 5) to insulating (>+0.3 V vs SCE at pH 5) on addition of hydrogen peroxide. The change in conductivity is brought about by oxidation of the poly(aniline) film by direct electrochemical communication between the enzyme and the conducting polymer. This was confirmed by measuring the potential of the poly(aniline) film during switching of the conductivity in the presence of hydrogen peroxide. The devices can be reused by rereducing the poly(aniline) electrochemically to a potential below +0.3 V vs SCE. A blind test showed that the device can be used to determine unknown concentrations of H(2)O(2) in solution and that, when used with hydrogen peroxide concentrations below 0.5 mmol dm(-)(3), the same device maybe reused several times. The possible development of devices of this type for use in applications requiring the measurement of low levels of hydrogen peroxide or horseradish peroxidase is discussed.

Experiments in anodic film effects during electrorefining of scrap U-10Mo fuels in support of modeling efforts

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

Van Kleeck, M.; Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439; Willit, J.

A monolithic uranium molybdenum alloy clad in zirconium has been proposed as a low enriched uranium (LEU) fuel option for research and test reactors, as part of the Reduced Enrichment for Research and Test Reactors program. Scrap from the fuel's manufacture will contain a significant portion of recoverable LEU. Pyroprocessing has been identified as an option to perform this recovery. A model of a pyroprocessing recovery procedure has been developed to assist in refining the LEU recovery process and designing the facility. Corrosion theory and a two mechanism transport model were implemented on a Mat-Lab platform to perform the modeling.more » In developing this model, improved anodic behavior prediction became necessary since a dense uranium-rich salt film was observed at the anode surface during electrorefining experiments. Experiments were conducted on uranium metal to determine the film's character and the conditions under which it forms. The electro-refiner salt used in all the experiments was eutectic LiCl/KCl containing UCl{sub 3}. The anodic film material was analyzed with ICP-OES to determine its composition. Both cyclic voltammetry and potentiodynamic scans were conducted at operating temperatures between 475 and 575 C. degrees to interrogate the electrochemical behavior of the uranium. The results show that an anodic film was produced on the uranium electrode. The film initially passivated the surface of the uranium on the working electrode. At high over potentials after a trans-passive region, the current observed was nearly equal to the current observed at the initial active level. Analytical results support the presence of K{sub 2}UCl{sub 6} at the uranium surface, within the error of the analytical method.« less

Destination of organic pollutants during electrochemical oxidation of biologically-pretreated dye wastewater using boron-doped diamond anode.

PubMed

Zhu, Xiuping; Ni, Jinren; Wei, Junjun; Xing, Xuan; Li, Hongna

2011-05-15

Electrochemical oxidation of biologically-pretreated dye wastewater was performed in a boron-doped diamond (BDD) anode system. After electrolysis of 12h, the COD was decreased from 532 to 99 mg L(-1) (<100 mg L(-1), the National Discharge Standard of China). More importantly, the destination of organic pollutants during electrochemical oxidation process was carefully investigated by molecular weight distribution measurement, resin fractionation, ultraviolet-visible spectroscopy, HPLC and GC-MS analysis, and toxicity test. As results, most organic pollutants were completely removed by electrochemical oxidation and the rest was primarily degraded to simpler compounds (e.g., carboxylic acids and short-chain alkanes) with less toxicity, which demonstrated that electrochemical oxidation of biologically-pretreated dye wastewater with BDD anode was very effective and safe. Especially, the performance of BDD anode system in degradation of large molecular organics such as humic substances makes it very promising in practical applications as an advanced treatment of biologically-pretreated wastewaters. Copyright © 2011 Elsevier B.V. All rights reserved.

Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic-sulfuric acid anodizing processes of ZL114A aluminum alloys

NASA Astrophysics Data System (ADS)

Hua, Lei; Liu, Jian-hua; Li, Song-mei; Yu, Mei; Wang, Lei; Cui, Yong-xin

2015-03-01

The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The anodic oxidation was performed at 25°C and a constant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the approximate ranges of 10-20 nm and 5-10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

Electrochemical modification of properties of ZnO films

NASA Astrophysics Data System (ADS)

Abe, Koji; Okubo, Takamasa; Ishikawa, Hirohito

2017-12-01

The properties of Al-doped ZnO films and Li- and Al-doped ZnO films were modified by electrochemical treatment. A constant current was applied between a ZnO film and a Pt electrode in an electrolyte solution. The sheet resistance of the ZnO film increased and decreased depending on the direction of current flow during the electrochemical treatment. When the ZnO film was used as a cathode (forward biased condition), the sheet resistance of the ZnO film decreased with increasing treatment time. The optical bandgap of the H2-annealed ZnO film also depended on the direction of current flow and increased under the forward biased condition. The electrochemical treatment caused the Burstein-Moss effect.

Electrochemical anodizing treatment to enhance localized corrosion resistance of pure titanium.

PubMed

Prando, Davide; Brenna, Andrea; Bolzoni, Fabio M; Diamanti, Maria V; Pedeferri, Mariapia; Ormellese, Marco

2017-01-26

Titanium has outstanding corrosion resistance due to the thin protective oxide layer that is formed on its surface. Nevertheless, in harsh and severe environments, pure titanium may suffer localized corrosion. In those conditions, costly titanium alloys containing palladium, nickel and molybdenum are used. This purpose investigated how it is possible to control corrosion, at lower cost, by electrochemical surface treatment on pure titanium, increasing the thickness of the natural oxide layer. Anodic oxidation was performed on titanium by immersion in H2SO4 solution and applying voltages ranging from 10 to 80 V. Different anodic current densities were considered. Potentiodynamic tests in chloride- and fluoride-containing solutions were carried out on anodized titanium to determine the pitting potential. All tested anodizing treatments increased corrosion resistance of pure titanium, but never reached the performance of titanium alloys. The best corrosion behavior was obtained on titanium anodized at voltages lower than 40 V at 20 mA/cm2. Titanium samples anodized at low cell voltage were seen to give high corrosion resistance in chloride- and fluoride-containing solutions. Electrolyte bath and anodic current density have little effect on the corrosion behavior.

Shape Effect of Electrochemical Chloride Extraction in Structural Reinforced Concrete Elements Using a New Cement-Based Anodic System

PubMed Central

Carmona, Jesús; Climent, Miguel-Ángel; Antón, Carlos; de Vera, Guillem; Garcés, Pedro

2015-01-01

This article shows the research carried out by the authors focused on how the shape of structural reinforced concrete elements treated with electrochemical chloride extraction can affect the efficiency of this process. Assuming the current use of different anode systems, the present study considers the comparison of results between conventional anodes based on Ti-RuO2 wire mesh and a cement-based anodic system such as a paste of graphite-cement. Reinforced concrete elements of a meter length were molded to serve as laboratory specimens, to closely represent authentic structural supports, with circular and rectangular sections. Results confirm almost equal performances for both types of anode systems when electrochemical chloride extraction is applied to isotropic structural elements. In the case of anisotropic ones, such as rectangular sections with no uniformly distributed rebar, differences in electrical flow density were detected during the treatment. Those differences were more extreme for Ti-RuO2 mesh anode system. This particular shape effect is evidenced by obtaining the efficiencies of electrochemical chloride extraction in different points of specimens.

Sputtering Deposition of Sn-Mo-Based Composite Anode for Thin-Film Li-Ion Batteries

NASA Astrophysics Data System (ADS)

Mani Chandran, T.; Balaji, S.

2016-06-01

The role of electrochemically inactive molybdenum in alleviating the anomalous volume expansion of tin anode upon charge-discharge cycling has been investigated. Tin-molybdenum thin-film composite anodes for Li-ion batteries were prepared using a direct-current sputtering method from a tin metal target incorporating molybdenum element. Results of structural and compositional analyses confirmed the presence of tin and molybdenum. The elemental ratio obtained from energy-dispersive x-ray spectroscopy confirmed the feasibility of tailoring the thin-film composition by varying the ratio of metallic elements present in the sputtering target. Scanning electron micrographs of the samples revealed the occurrence of flower-like open morphology with Mo inclusion in a Sn matrix. The gravimetric discharge capacity for pure Sn, Sn-rich, and Mo-rich samples was 733 mAh g-1, 572 mAh g-1, and 439 mAh g-1, respectively, with capacity retention after 50 cycles of 22%, 61%, and 74%, respectively. Mo inclusion reduced the surface resistivity of the Sn anode after the initial charge-discharge cycle. The charge-transfer resistance after the first cycle for pure Sn, Sn-rich, and Mo-rich samples was 17.395 Ω, 5.345 Ω, and 2.865 Ω, respectively. The lithium-ion diffusion coefficient also increased from 8.68 × 10-8 cm2S-1 for the pure Sn sample to 2.98 × 10-5 cm2S-1 for the Mo-rich sample.

Use of a Soluble Anode in Electrodeposition of Thick Bismuth Telluride Layers

NASA Astrophysics Data System (ADS)

Maas, M.; Diliberto, S.; de Vaulx, C.; Azzouz, K.; Boulanger, C.

2014-10-01

Integration of thermoelectric devices within an automotive heat exchanger could enable conversion of lost heat into electrical energy, contributing to improved total output from the engine. For this purpose, synthesis of thick bismuth telluride (Bi2Te3) films is required. Bismuth telluride has been produced by an electrochemical method in nitric acid with a sacrificial bismuth telluride anode as the source of cations. The binary layer grows on the working electrode while the counter-electrode, a Bi2Te3 disk obtained by high frequency melting, is oxidized to BiIII and TeIV. This process leads to auto-regeneration of the solution without modification of its composition. The thickness of films deposited by use of the Bi2Te3 anode was approximately 10 times that without. To demonstrate the utility of a soluble anode in electrochemical deposition, we report characterization of the composition and morphology of the films obtained under different experimental conditions. Perfectly dense and regular Bi2Te3 films (˜400 μm) with low internal stress and uniform composition across the cross-section were prepared. Their thermoelectric properties were assessed.

Fabrication of anodic aluminium oxide templates on curved surfaces.

PubMed

Yin, Aijun; Guico, Rodney S; Xu, Jimmy

2007-01-24

Aluminium anodization provides a simple and inexpensive way to obtain nanoporous templates with uniform and controllable pore diameters and periods over a wide range. Moreover, one of the interesting possibilities afforded by the anodization process is that the anodization can take place on arbitrary surfaces, such as curved surfaces, which has not yet been well studied or applied in nanofabrication. In this paper, we characterize the anodization of Al films on silicon substrates with a curved top surface. The structures of the resultant anodic aluminium oxide (AAO) films are examined by scanning electron microscopy. Unique features including cessation, bending, and branching of pore channels are observed in the curved area. Possible growth mechanisms are proposed, which can also contribute to the understanding of the self-organization mechanism in the formation of porous AAO membranes. The new structures may open new opportunities in optical, electronic and electrochemical applications.

Separator for electrochemical cells

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

Griffin, R.A.

1988-12-27

An electrochemical cell is described comprising a sealed casing; an anode, a cathode, a separator positioned between the anode and the cathode, and a non-aqueous electrolyte sealed in the casing; a pair of electrical terminals on the casing; means for electrically isolating the electrical terminals from each other; and means for electrically connecting the anode to one terminal and the cathode to the other terminal; wherein the anode is comprised of lithium foil, the cathode is comprised of manganese dioxide, and the separator consists essentially of a microporous polypropylene film having a thickness of about 1.5 mils and internal voidsmore » of about 60% by volume; wherein the anode, cathode, and separator are spirally wound together in a jelly roll configuration.« less

Nonradical oxidation from electrochemical activation of peroxydisulfate at Ti/Pt anode: Efficiency, mechanism and influencing factors.

PubMed

Song, Haoran; Yan, Linxia; Ma, Jun; Jiang, Jin; Cai, Guangqiang; Zhang, Wenjuan; Zhang, Zhongxiang; Zhang, Jiaming; Yang, Tao

2017-06-01

Electrochemical activation of peroxydisulfate (PDS) at Ti/Pt anode was systematically investigated for the first time in this work. The synergistic effect produced from the combination of electrolysis and the addition of PDS demonstrates that PDS can be activated at Ti/Pt anode. The selective oxidation towards carbamazepine (CBZ), sulfamethoxazole (SMX), propranolol (PPL), benzoic acid (BA) rather than atrazine (ATZ) and nitrobenzene (NB) was observed in electrochemical activation of PDS process. Moreover, addition of excess methanol or tert-butanol had negligible impact on CBZ (model compound) degradation, demonstrating that neither sulfate radical (SO 4 - ) nor hydroxyl radical (HO) was produced in electrochemical activation of PDS process. Direct oxidation (PDS oxidation alone and electrolysis) and nonradical oxidation were responsible for the degradation of contaminants. The results of linear sweep voltammetry (LSV) and chronoamperometry suggest that electric discharge may integrate PDS molecule with anode surface into a unique transition state structure, which is responsible for the nonradical oxidation in electrochemical activation of PDS process. Adjustment of the solution pH from 1.0 to 7.0 had negligible effect on CBZ degradation. Increase of either PDS concentration or current density facilitated the degradation of CBZ. The presence of chloride ion (Cl - ) significantly enhanced CBZ degradation, while addition of bicarbonate (HCO 3 - ), phosphate (PO 4 3- ) and humic acid (HA) all inhibited CBZ degradation with the order of HA > HCO 3 -  > PO 4 3- . The degradation products of CBZ and chlorinated products were also identified. Electrochemical activation of PDS at Ti/Pt anode may serve as a novel technology for selective oxidation of organic contaminants in water and soil. Copyright © 2017. Published by Elsevier Ltd.

Cerium-modified doped strontium titanate compositions for solid oxide fuel cell anodes and electrodes for other electrochemical devices

DOEpatents

Marina, Olga A [Richland, WA; Stevenson, Jeffry W [Richland, WA

2010-03-02

The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells and electrochemical devices such as solid oxide fuel cells, electrolyzers, sensors, pumps and the like, the compositions comprising cerium-modified doped strontium titanate. The invention also provides novel methods for making and using anode material compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having anodes comprising the compositions.

Cerium-modified doped strontium titanate compositions for solid oxide fuel cell anodes and electrodes for other electrochemical devices

DOEpatents

Marina, Olga A [Richland, WA; Stevenson, Jeffry W [Richland, WA

2010-11-23

The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells and electrochemical devices such as solid oxide fuel cells, electrolyzers, sensors, pumps and the like, the compositions comprising cerium-modified doped strontium titanate. The invention also provides novel methods for making and using anode material compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having anodes comprising the compositions.

Electrochemical Properties of Si Film Electrodes Containing TiNi Thin-Film Current Collectors

NASA Astrophysics Data System (ADS)

Im, Yeon-min; Noh, Jung-pil; Cho, Gyu-bong; Nam, Tea-hyun

2018-03-01

A 50.3Ti-49.7Ni thin film fabricated by DC sputtering was employed as a current collector of Si film electrode. The structural and electrochemical properties of Si/TiNi film electrode were compared with those of a Si/Cu film electrode. The TiNi film with cluster-like structures composed of B2 austenitic phase at room temperature displayed the high electrochemical stability for Li ions. The amorphous Si film deposited on the TiNi film also consisted of cluster-like structures on the surface. The Si film grown on the TiNi film current collector (Si/TiNi electrode) demonstrated a high columbic efficiency of 87% at the first cycle (363 μAh/cm2 of charge capacity and 314 μAh/cm2 of discharge capacity). The Si/TiNi electrode exhibited better electrochemical properties in terms of capacity, cycle performance, and structural stability compared to the Si electrode with a conventional Cu foil current collector.

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors.

PubMed

Yang, Jiang; Kwak, Tae-Joon; Zhang, Xiaodong; McClain, Robert; Chang, Woo-Jin; Gunasekaran, Sundaram

2016-11-22

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (µPAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

Hollow carbon nanospheres/silicon/alumina core-shell film as an anode for lithium-ion batteries

PubMed Central

Li, Bing; Yao, Fei; Bae, Jung Jun; Chang, Jian; Zamfir, Mihai Robert; Le, Duc Toan; Pham, Duy Tho; Yue, Hongyan; Lee, Young Hee

2015-01-01

Hollow carbon nanospheres/silicon/alumina (CNS/Si/Al2O3) core-shell films obtained by the deposition of Si and Al2O3 on hollow CNS interconnected films are used as the anode materials for lithium-ion batteries. The hollow CNS film acts as a three dimensional conductive substrate and provides void space for silicon volume expansion during electrochemical cycling. The Al2O3 thin layer is beneficial to the reduction of solid-electrolyte interphase (SEI) formation. Moreover, as-designed structure holds the robust surface-to-surface contact between Si and CNSs, which facilitates the fast electron transport. As a consequence, the electrode exhibits high specific capacity and remarkable capacity retention simultaneously: 1560 mA h g−1 after 100 cycles at a current density of 1 A g−1 with the capacity retention of 85% and an average decay rate of 0.16% per cycle. The superior battery properties are further confirmed by cyclic voltammetry (CV) and impedance measurement. PMID:25564245

Porous TiO2-ZrO2 thin film formed by electrochemical technique to improve the biocompatibility of titanium alloy in physiological environment

NASA Astrophysics Data System (ADS)

Benea, L.; Dănăilă, E.; Ponthiaux, P.

2017-02-01

Porous Ti and Ti alloys have received increasing research interest for bone tissue engineering, especially for dental and orthopaedic implants because they provide cell ingrowths and vascularization, improving of adhesion and osseointegration. The tribocorrosion process is encountered in orthopaedic and dentistry applications, since it is known that the implants are often exposed to simultaneous chemical/electrochemical and mechanical stresses. The purpose of this study was to carry out a systematic investigation of the tribo-electrochemical performance of porous TiO2-ZrO2 thin film formed by anodization of Ti-10Zr alloy surface in an artificial saliva solution and to compare the resulted performance with that of the untreated Ti-10Zr alloy surface in order to be applied for biomedical use. The in situ electrochemical technique used for investigation of tribo-electrochemical degradation was the open circuit potential (OCP) measurement performed before, during and after sliding tests. The results presented herein show that controlled anodic oxidation method can significantly improve the tribocorrosion and friction performances of Ti-10Zr alloy surface intended for biomedical applications.

Synthesis, Characterization, and Electrochemical Properties of Polyaniline Thin Films

NASA Astrophysics Data System (ADS)

Rami, Soukaina

Conjugated polymers have been used in various applications (battery, supercapacitor, electromagnetic shielding, chemical sensor, biosensor, nanocomposite, light-emitting-diode, electrochromic display etc.) due to their excellent conductivity, electrochemical and optical properties, and low cost. Polyaniline has attracted the researchers from all disciplines of science, engineering, and industry due to its redox properties, environmental stability, conductivity, and optical properties. Moreover, it is a polymer with fast electroactive switching and reversible properties displayed at low potential, which is an important feature in many applications. The thin oriented polyaniline films have been fabricated using self-assembly, Langmuir-Blodgett, in-situ self-assembly, layer-by-layer, and electrochemical technique. The focus of this thesis is to synthesize and characterize polyaniline thin films with and without dyes. Also, the purpose of this thesis is to find the fastest electroactive switching PANI electrode in different electrolytic medium by studying their electrochemical properties. These films were fabricated using two deposition techniques: in-situ self-assembly and electrochemical deposition. The characterization of these films was done using techniques such as Fourier Transform Infrared Spectroscopy (FTIR), UV-spectroscopy, Scanning Electron Microscope (SEM), and X-Ray Diffraction (XRD). FTIR and UV-spectroscopy showed similar results in the structure of the polyaniline films. However, for the dye incorporated films, since there was an addition in the synthesis of the material, peak locations shifted, and new peaks corresponding to these materials appeared. The 1 layer PANI showed compact film morphology, comparing to other PANI films, which displayed a fiber-like structure. Finally, the electrochemical properties of these thin films were studied using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) in

Electrochemical preparation of poly(methylene blue)/graphene nanocomposite thin films

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

Erçarıkcı, Elif; Dağcı, Kader; Topçu, Ezgi

2014-07-01

Highlights: • Poly(MB)/graphene thin films are prepared by a simple electrochemical approach. • Graphene layers in the film show a broad band in visible region of absorbance spectra. • Morphology of composite films indicates both disordered and ordered regions. • XRD reveals that nanocomposite films include rGO layers after electropolymerization process. • Chemically prepared graphene is better than electrochemically prepared graphene for electrooxidation of nitrite. - Abstract: Poly(methylene blue)/graphene nanocomposite thin films were prepared by electropolymerization of methylene blue in the presence of graphene which have been synthesized by two different methods of a chemical oxidation process and an electrochemicalmore » approach. Synthesized nanocomposite thin films were characterized by using cyclic voltammetry, UV–vis. absorption spectroscopy, powder X-ray diffraction, and scanning tunneling microscopy techniques. Electrocatalytical properties of prepared poly(methylene blue)/graphene nanocomposite films were compared toward electrochemical oxidation of nitrite. Under optimized conditions, electrocatalytical effect of nanocomposite films of chemically prepared graphene through electrochemical oxidation of nitrite was better than that of electrochemically prepared graphene.« less

Electrochemical surface modification of carbon mesh anode to improve the performance of air-cathode microbial fuel cells.

PubMed

Luo, Jianmei; Chi, Meiling; Wang, Hongyu; He, Huanhuan; Zhou, Minghua

2013-12-01

A convenient and promising alternative to surface modification of carbon mesh anode was fulfilled by electrochemical oxidation in the electrolyte of nitric acid or ammonium nitrate at ambient temperature. It was confirmed that such an anode modification method was low cost and effective not only in improving the efficiency of power generation in microbial fuel cells (MFCs) for synthetic wastewater treatment, but also helping to reduce the period for MFCs start-up. The MFCs with anode modification in electrolyte of nitric acid performed the best, achieving a Coulombic efficiency enhancement of 71 %. As characterized, the electrochemical modification resulted in the decrease of the anode potential and internal resistance but the increase of current response and nitrogen-containing and oxygen-containing functional groups on the carbon surface, which might contribute to the enhancement on the performances of MFCs.

Effects of Alloying Element Ca on the Corrosion Behavior and Bioactivity of Anodic Films Formed on AM60 Mg Alloys

PubMed Central

Anawati, Anawati; Asoh, Hidetaka; Ono, Sachiko

2016-01-01

Effects of alloying element Ca on the corrosion behavior and bioactivity of films formed by plasma electrolytic oxidation (PEO) on AM60 alloys were investigated. The corrosion behavior was studied by conducting electrochemical tests in 0.9% NaCl solution while the bioactivity was evaluated by soaking the specimens in simulated body fluid (SBF). Under identical anodization conditions, the PEO film thicknesses increased with increasing Ca content in the alloys, which enhanced the corrosion resistance in NaCl solution. Thicker apatite layers grew on the PEO films of Ca-containing alloys because Ca was incorporated into the PEO film and because Ca was present in the alloys. Improvement of corrosion resistance and bioactivity of the PEO-coated AM60 by alloying with Ca may be beneficial for biodegradable implant applications. PMID:28772371

Tin Oxynitride Anodes by Atomic Layer Deposition for Solid-State Batteries

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

Stewart, David M.; Pearse, Alexander J.; Kim, Nam S.

Major advances in thin-film solid-state batteries (TFSSBs) may capitalize on 3D structuring using high-aspect-ratio substrates such as nanoscale pits, pores, trenches, flexible polymers, and textiles. This will require conformal processes such as atomic layer deposition (ALD) for every active functional component of the battery. In this paper, we explore the deposition and electrochemical properties of SnO 2, SnN y, and SnO xN y thin films as TFSSB anode materials, grown by ALD using tetrakisdimethylamido(tin), H 2O, and N 2 plasma as precursors. By controlling the dose ratio between H 2O and N 2, the N–O fraction can be tuned betweenmore » 0% N and 95% N. The electrochemical properties of these materials were tested across a composition range varying from pure SnO 2, to SnON intermediates, and pure SnNy. In TFSSBs, the SnNy anodes are found to be more stable during cycling than the SnO 2 or SnO xN y films, with an initial reversible capacity beyond that of Li–Sn alloying, retaining 75% of their capacity over 200 cycles compared to only 50% for SnO 2. Lastly, the performance of the SnO xN y anodes indicates that SnN y anodes should not be negatively impacted by small levels of O contamination.« less

Tin Oxynitride Anodes by Atomic Layer Deposition for Solid-State Batteries

DOE PAGES

Stewart, David M.; Pearse, Alexander J.; Kim, Nam S.; ...

2018-03-30

Major advances in thin-film solid-state batteries (TFSSBs) may capitalize on 3D structuring using high-aspect-ratio substrates such as nanoscale pits, pores, trenches, flexible polymers, and textiles. This will require conformal processes such as atomic layer deposition (ALD) for every active functional component of the battery. In this paper, we explore the deposition and electrochemical properties of SnO 2, SnN y, and SnO xN y thin films as TFSSB anode materials, grown by ALD using tetrakisdimethylamido(tin), H 2O, and N 2 plasma as precursors. By controlling the dose ratio between H 2O and N 2, the N–O fraction can be tuned betweenmore » 0% N and 95% N. The electrochemical properties of these materials were tested across a composition range varying from pure SnO 2, to SnON intermediates, and pure SnNy. In TFSSBs, the SnNy anodes are found to be more stable during cycling than the SnO 2 or SnO xN y films, with an initial reversible capacity beyond that of Li–Sn alloying, retaining 75% of their capacity over 200 cycles compared to only 50% for SnO 2. Lastly, the performance of the SnO xN y anodes indicates that SnN y anodes should not be negatively impacted by small levels of O contamination.« less

Nanostructured tungsten trioxide thin films synthesized for photoelectrocatalytic water oxidation: a review.

PubMed

Zhu, Tao; Chong, Meng Nan; Chan, Eng Seng

2014-11-01

The recent developments of nanostructured WO3 thin films synthesized through the electrochemical route of electrochemical anodization and cathodic electrodeposition for the application in photoelectrochemical (PEC) water splitting are reviewed. The key fundamental reaction mechanisms of electrochemical anodization and cathodic electrodeposition methods for synthesizing nanostructured WO3 thin films are explained. In addition, the effects of metal oxide precursors, electrode substrates, applied potentials and current densities, and annealing temperatures on size, composition, and thickness of the electrochemically synthesized nanostructured WO3 thin films are elucidated in detail. Finally, a summary is given for the general evaluation practices used to calculate the energy conversion efficiency of nanostructured WO3 thin films and a recommendation is provided to standardize the presentation of research results in the field to allow for easy comparison of reported PEC efficiencies in the near future. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method

PubMed Central

Ning, Xuewen; Wang, Xixin; Yu, Xiaofei; Zhao, Jianling; Wang, Mingli; Li, Haoran; Yang, Yang

2016-01-01

Mn-doped TiO2 micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm2 at a current density of 3 mA/cm2 when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm2, and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work. PMID:26940546

Li 2S Film Formation on Lithium Anode Surface of Li–S batteries

DOE PAGES

Liu, Zhixiao; Bertolini, Samuel; Balbuena, Perla B.; ...

2016-02-02

The precipitation of lithium sulfide (Li 2S) on the Li metal anode surface adversely impacts the performance of lithium–sulfur (Li–S) batteries. In this work, a first-principles approach including density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations is employed to theoretically elucidate the Li 2S/Li metal surface interactions and the nucleation and growth of a Li 2S film on the anode surface due to long-chain polysulfide decomposition during battery operation. DFT analyses of the energetic properties and electronic structures demonstrate that a single molecule adsorption on Li surface releases energy forming chemical bonds between the S atoms andmore » Li atoms from the anode surface. Reaction pathways of the Li 2S film formation on Li metal surfaces are investigated based on DFT calculations. It is found that a distorted Li 2S (111) plane forms on a Li(110) surface and a perfect Li 2S (111) plane forms on a Li(111) surface. The total energy of the system decreases along the reaction pathway; hence Li 2S film formation on the Li anode surface is thermodynamically favorable. Finally, the calculated difference charge density of the Li 2S film/Li surface suggests that the precipitated film would interact with the Li anode via strong chemical bonds. AIMD simulations reveal the role of the anode surface structure and the origin of the Li 2S formation via decomposition of Li 2S 8 polysulfide species formed at the cathode side and dissolved in the electrolyte medium in which they travel to the anode side during battery cycling.« less

Li2S Film Formation on Lithium Anode Surface of Li-S batteries.

PubMed

Liu, Zhixiao; Bertolini, Samuel; Balbuena, Perla B; Mukherjee, Partha P

2016-02-01

The precipitation of lithium sulfide (Li2S) on the Li metal anode surface adversely impacts the performance of lithium-sulfur (Li-S) batteries. In this study, a first-principles approach including density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations is employed to theoretically elucidate the Li2S/Li metal surface interactions and the nucleation and growth of a Li2S film on the anode surface due to long-chain polysulfide decomposition during battery operation. DFT analyses of the energetic properties and electronic structures demonstrate that a single molecule adsorption on Li surface releases energy forming chemical bonds between the S atoms and Li atoms from the anode surface. Reaction pathways of the Li2S film formation on Li metal surfaces are investigated based on DFT calculations. It is found that a distorted Li2S (111) plane forms on a Li(110) surface and a perfect Li2S (111) plane forms on a Li(111) surface. The total energy of the system decreases along the reaction pathway; hence Li2S film formation on the Li anode surface is thermodynamically favorable. The calculated difference charge density of the Li2S film/Li surface suggests that the precipitated film would interact with the Li anode via strong chemical bonds. AIMD simulations reveal the role of the anode surface structure and the origin of the Li2S formation via decomposition of Li2S8 polysulfide species formed at the cathode side and dissolved in the electrolyte medium in which they travel to the anode side during battery cycling.

Li 2S Film Formation on Lithium Anode Surface of Li–S batteries

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

Liu, Zhixiao; Bertolini, Samuel; Balbuena, Perla B.

The precipitation of lithium sulfide (Li 2S) on the Li metal anode surface adversely impacts the performance of lithium–sulfur (Li–S) batteries. In this work, a first-principles approach including density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations is employed to theoretically elucidate the Li 2S/Li metal surface interactions and the nucleation and growth of a Li 2S film on the anode surface due to long-chain polysulfide decomposition during battery operation. DFT analyses of the energetic properties and electronic structures demonstrate that a single molecule adsorption on Li surface releases energy forming chemical bonds between the S atoms andmore » Li atoms from the anode surface. Reaction pathways of the Li 2S film formation on Li metal surfaces are investigated based on DFT calculations. It is found that a distorted Li 2S (111) plane forms on a Li(110) surface and a perfect Li 2S (111) plane forms on a Li(111) surface. The total energy of the system decreases along the reaction pathway; hence Li 2S film formation on the Li anode surface is thermodynamically favorable. Finally, the calculated difference charge density of the Li 2S film/Li surface suggests that the precipitated film would interact with the Li anode via strong chemical bonds. AIMD simulations reveal the role of the anode surface structure and the origin of the Li 2S formation via decomposition of Li 2S 8 polysulfide species formed at the cathode side and dissolved in the electrolyte medium in which they travel to the anode side during battery cycling.« less

Fundamental Investigation of Silicon Anode in Lithium-Ion Cells

NASA Technical Reports Server (NTRS)

Wu, James J.; Bennett, William R.

2012-01-01

Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is 10 times of graphite and it is an abundant element on Earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. Understanding solid electrolyte interphase (SEI) formation along with the lithium ion insertion/de-insertion kinetics in silicon anodes will provide greater insight into overcoming these issues, thereby lead to better cycle performance. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of a Si anode during the first cycle; the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes, and the combination of cyclic voltammetry with impedance spectroscopy provides a useful tool to evaluate the effectiveness of the design modifications on the Si anode performance.

A lithium air battery with a lithiated Al-carbon anode.

PubMed

Guo, Ziyang; Dong, XiaoLi; Wang, Yonggang; Xia, Yongyao

2015-01-14

A lithiated Al-carbon composite electrode with a uniform SEI film was prepared by an electrochemical method, and was then coupled with an O2 catalytic electrode to form a rechargeable Li-O2 (or air) battery with a LixAl-C anode.

Photoluminescence emission of nanoporous anodic aluminum oxide films prepared in phosphoric acid

PubMed Central

2012-01-01

The photoluminescence emission of nanoporous anodic aluminum oxide films formed in phosphoric acid is studied in order to explore their defect-based subband electronic structure. Different excitation wavelengths are used to identify most of the details of the subband states. The films are produced under different anodizing conditions to optimize their emission in the visible range. Scanning electron microscopy investigations confirm pore formation in the produced layers. Gaussian analysis of the emission data indicates that subband states change with anodizing parameters, and various point defects can be formed both in the bulk and on the surface of these nanoporous layers during anodizing. PMID:23272786

Buried anode lithium thin film battery and process for forming the same

DOEpatents

Lee, Se-Hee; Tracy, C. Edwin; Liu, Ping

2004-10-19

A reverse configuration, lithium thin film battery (300) having a buried lithium anode layer (305) and process for making the same. The present invention is formed from a precursor composite structure (200) made by depositing electrolyte layer (204) onto substrate (201), followed by sequential depositions of cathode layer (203) and current collector (202) on the electrolyte layer. The precursor is subjected to an activation step, wherein a buried lithium anode layer (305) is formed via electroplating a lithium anode layer at the interface of substrate (201) and electrolyte film (204). The electroplating is accomplished by applying a current between anode current collector (201) and cathode current collector (202).

Anodized titanium and stainless steel in contact with CFRP: an electrochemical approach considering galvanic corrosion.

PubMed

Mueller, Yves; Tognini, Roger; Mayer, Joerg; Virtanen, Sannakaisa

2007-09-15

The combination of different materials in an implant gives the opportunity to better fulfill the requirements that are needed to improve the healing process. However, using different materials increases the risk of galvanic coupling corrosion. In this study, coupling effects of gold-anodized titanium, stainless steel for biomedical applications, carbon fiber reinforced polyetheretherketone (CFRP), and CFRP containing tantalum fibers are investigated electrochemically and by long-term immersion experiments in simulated body fluid (SBF). Potentiodynamic polarization experiments (i/E curves) and electrochemical impedance spectroscopy (EIS) of the separated materials showed a passive behavior of the metallic samples. Anodized titanium showed no corrosion attacks, whereas stainless steel is highly susceptibility for localized corrosion. On the other side, an active dissolution behavior of both of the CFRPs in the given environment could be determined, leading to delaminating of the carbon fibers from the matrix. Long-term immersion experiments were carried out using a set-up especially developed to simulate coupling conditions of a point contact fixator system (PC-Fix) in a biological environment. Electrochemical data were acquired in situ during the whole immersion time. The results of the immersion experiments correlate with the findings of the electrochemical investigation. Localized corrosion attacks were found on stainless steel, whereas anodized titanium showed no corrosion attacks. No significant differences between the two CFRP types could be found. Galvanic coupling corrosion in combination with crevice conditions and possible corrosion mechanisms are discussed. Copyright 2007 Wiley Periodicals, Inc.

Structural, optical and electrochemical properties of F-doped vanadium oxide transparent semiconducting thin films

NASA Astrophysics Data System (ADS)

Mousavi, M.; Khorrami, Gh. H.; Kompany, A.; Yazdi, Sh. Tabatabai

2017-12-01

In this study, F-doped vanadium oxide thin films with doping levels up to 60 at % were prepared by spray pyrolysis method on glass substrates. To measure the electrochemical properties, some films were deposited on fluorine-tin oxide coated glass substrates. The effect of F-doping on the structural, electrical, optical and electrochemical properties of vanadium oxide samples was investigated. The X-ray diffractographs analysis has shown that all the samples grow in tetragonal β-V2O5 phase structure with the preferred orientation of [200]. The intensity of (200) peak belonging to β-V2O5 phase was strongest in the undoped vanadium oxide film. The scanning electron microscopy images show that the samples have nanorod- and nanobelt-shaped structure. The size of the nanobelts in the F-doped vanadium oxide films is smaller than that in the pure sample and the width of the nanobelts increases from 30 to 70 nm with F concentration. With increasing F-doping level from 10 to 60 at %, the resistivity, the transparency and the optical band gap decrease from 111 to 20 Ω cm, 70 to 50% and 2.4 to 2.36 eV, respectively. The cyclic voltammogram (CV) results show that the undoped sample has the most extensive CV and by increasing F-doping level from 20 to 60 at %, the area of the CV is expanded. The anodic and cathodic peaks in F-doped samples are stronger.

Li+-Permeable Film on Lithium Anode for Lithium Sulfur Battery.

PubMed

Yang, Yan-Bo; Liu, Yun-Xia; Song, Zhiping; Zhou, Yun-Hong; Zhan, Hui

2017-11-08

Lithium-sulfur (Li-S) battery is an important candidate for next-generation energy storage. However, the reaction between polysulfide and lithium (Li) anode brings poor cycling stability, low Coulombic efficiency, and Li corrosion. Herein, we report a Li protection technology. Li metal was treated in crown ether containing electrolyte, and thus, treated Li was further used as the anode in Li-S cell. Due to the coordination between Li + and crown ether, a Li + -permeable film can be formed on Li, and the film is proved to be able to block the detrimental reaction between Li anode and polysulfide. By using the Li anode pretreated in 2 wt % B15C5-containing electrolyte, Li-S cell exhibits significantly improved cycling stability, such as∼900 mAh g -1 after 100 cycles, and high Coulombic efficiency of>93%. In addition, such effect is also notable when high S loading condition is applied.

Effect of NaNO3 concentration on anodic electrochemical behavior on the Sb surface in NaOH solution

NASA Astrophysics Data System (ADS)

He, Yun-long; Xu, Rui-dong; He, Shi-wei; Chen, Han-sen; Li, Kuo; Zhu, Yun; Shen, Qing-feng

2018-03-01

The effect of NaNO3 concentration on the anodic electrochemical behavior of antimony in 4 M NaOH solution was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses. The mechanism of NO 3 - concentration effect on the anodic electrochemical behavior of antimony was proposed, and its availability was confirmed by experimental results. The effect of NaNO3 on the anodic behavior of antimony in NaOH solution can be interpreted as a stepwise formation of different antimony compounds with different NaNO3 concentrations. Metallic antimony is apt to be oxidized into Sb2O3 within the NaNO3 concentration range of 0-0.48 M. NaSbO3 can be found on the antimony surface when the NaNO3 concentration increases gradually. Insoluable NaSbO3 inhibits the anodic oxidation of antimony due to its shielding effect on the mass transport of the reactants and products. Surface morphology and composition were analyzed by X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM), and electron dispersion spectroscopy (EDS) analyses. Results indicate that the anodic oxidation layer is composed of Sb2O3, NaSbO3, and Sb. The atomic proportion of antimony in the form of NaSbO3 increases with increasing NaNO3 concentration due to the powerful oxidizing property of NaNO3.

Evaluating tetracycline degradation pathway and intermediate toxicity during the electrochemical oxidation over a Ti/Ti4O7 anode.

PubMed

Wang, Jianbing; Zhi, Dan; Zhou, Hao; He, Xuwen; Zhang, Dayi

2018-06-15

Tetracycline (TC) is one of the most widely used antibiotics with significant impacts on human health and thus it needs appropriate approaches for its removal. In the present study, we evaluated the performance and complete pathway of the TC electrochemical oxidation on a Ti/Ti 4 O 7 anode prepared by plasma spraying. Morphological data and composition analysis indicated a compact coating layer on the anode, which had the characteristic peaks of Ti 4 O 7 as active constituent. The TC electrochemical oxidation on the Ti/Ti 4 O 7 anode followed a pseudo-first-order kinetics, and the TC removal efficiency reached 95.8% in 40 min. The influential factors on TC decay kinetics included current density, anode-cathode distance and initial TC concentration. This anode also had high durability and the TC removal efficiency was maintained over 95% after five times reuse. For the first time, we unraveled the complete pathway of the TC electrochemical oxidation using high-performance liquid chromatograph (HPLC) and gas chromatograph (GC) coupled with mass spectrometer (MS). ·OH radicals produced from electrochemical oxidation attack the double bond, phenolic group and amine group of TC, forming a primary intermediate (m/z = 461), secondary intermediates (m/z = 432, 477 and 509) and tertiary intermediates (m/z = 480, 448 and 525). The latter were further oxidized to the key downstream intermediate (m/z = 496), followed by further downstream intermediates (m/z = 451, 412, 396, 367, 351, 298 and 253) and eventually short-chain carboxylic acids. We also evaluated the toxicity change during the electrochemical oxidation process with bioluminescent bacteria. The bioluminescence inhibition ratio peaked at 10 min (55.41%), likely owing to the high toxicity of intermediates with m/z = 461, 432 and 477 as obtained from quantitative structure activity relationship (QSAR) analysis. The bioluminescence inhibition ratio eventually decreased to 16.78% in 40�

MoOx thin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors

PubMed Central

Liu, Can; Li, Zhengcao; Zhang, Zhengjun

2013-01-01

In order to examine the potential application of non-stoichiometric molybdenum oxide as anode materials for aqueous micro-supercapacitors, conductive MoOx films (2 ⩽ x ⩽ 2.3) deposited via RF magnetron sputtering at different temperatures were systematically studied for composition, structure and electrochemical properties in an aqueous solution of Li2SO4. The MoOx (x ≈ 2.3) film deposited at 150 °C exhibited a higher areal capacitance (31 mF cm−2 measured at 5 mV s−1), best rate capability and excellent stability at potentials below −0.1 V versus saturated calomel electrode, compared to the films deposited at room temperature and at higher temperatures. These superior properties were attributed to the multi-valence composition and mixed-phase microstructure, i.e., the coexistence of MoO2 nanocrystals and amorphous MoOx (2.3 < x ⩽ 3). A mechanism combining Mo(IV) oxidation/reduction on the hydrated MoO2 grain surfaces and cation intercalation/extrusion is proposed to illustrate the pseudo-capacitive process. PMID:27877625

MoOx thin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Can; Li, Zhengcao; Zhang, Zhengjun

2013-12-01

In order to examine the potential application of non-stoichiometric molybdenum oxide as anode materials for aqueous micro-supercapacitors, conductive MoOx films (2 ⩽ x ⩽ 2.3) deposited via RF magnetron sputtering at different temperatures were systematically studied for composition, structure and electrochemical properties in an aqueous solution of Li2SO4. The MoOx (x ≈ 2.3) film deposited at 150 °C exhibited a higher areal capacitance (31 mF cm-2 measured at 5 mV s-1), best rate capability and excellent stability at potentials below -0.1 V versus saturated calomel electrode, compared to the films deposited at room temperature and at higher temperatures. These superior properties were attributed to the multi-valence composition and mixed-phase microstructure, i.e., the coexistence of MoO2 nanocrystals and amorphous MoOx (2.3 < x ⩽ 3). A mechanism combining Mo(IV) oxidation/reduction on the hydrated MoO2 grain surfaces and cation intercalation/extrusion is proposed to illustrate the pseudo-capacitive process.

The application of the barrier-type anodic oxidation method to thickness testing of aluminum films

NASA Astrophysics Data System (ADS)

Chen, Jianwen; Yao, Manwen; Xiao, Ruihua; Yang, Pengfei; Hu, Baofu; Yao, Xi

2014-09-01

The thickness of the active metal oxide film formed from a barrier-type anodizing process is directly proportional to its formation voltage. The thickness of the consumed portion of the metal film is also corresponding to the formation voltage. This principle can be applied to the thickness test of the metal films. If the metal film is growing on a dielectric substrate, when the metal film is exhausted in an anodizing process, because of the high electrical resistance of the formed oxide film, a sudden increase of the recorded voltage during the anodizing process would occur. Then, the thickness of the metal film can be determined from this voltage. As an example, aluminum films are tested and discussed in this work. This method is quite simple and is easy to perform with high precision.

Improvement of diamond-like carbon electrochemical corrosion resistance by addition of nanocrystalline diamond.

PubMed

Marciano, F R; Almeida, E C; Bonetti, L F; Corat, E J; Trava-Airoldi, V J

2010-02-15

Nanocrystalline diamond (NCD) particles were incorporated into diamond-like carbon (DLC) films in order to investigate NCD-DLC electrochemical corrosion resistance. The films were grown over 304 stainless steel using plasma-enhanced chemical vapor deposition. NCD particles were incorporated into DLC during the deposition process. The investigation of NCD-DLC electrochemical corrosion behavior was performed using potentiodynamic polarization against NaCl. NCD-DLC films presented more negative corrosion potential and lower anodic and cathodic current densities. The electrochemical analysis indicated that NCD-DLC films present superior impedance and polarization resistance compared to the pure DLC, which indicate that they are promising corrosion protective coatings in aggressive solutions. Copyright 2009 Elsevier Inc. All rights reserved.

Electrical characterization of TiO2 nanotubes synthesized through electrochemical anodizing method

NASA Astrophysics Data System (ADS)

Manescu Paltanea, Veronica; Paltanea, Gheorghe; Popovici, Dorina; Jiga, Gabriel

2016-05-01

In the present paper, the electrochemical anodizing method was used for the obtaining of TiO2 nanotube layers, developed on titanium surface. Self-organized titanium nanotubes were obtained when an aqueous solution of 49.5 wt % H2O - 49.5 wt % glycerol - 1 wt % HF was used as electrolyte, the anodizing time being equal to 8 hours and the applied voltage to 25 V. Scanning electron microscopy shows that the one-dimensional nanostructure has a tubular configuration with an inner diameter of approximately 60 nm and an outer diameter of approximately 100 nm. The electrical properties of these materials were analyzed through dielectric spectroscopy method.

Electrochemical properties of a lithium-impregnated metal foam anode for thermal batteries

NASA Astrophysics Data System (ADS)

Choi, Yu-Song; Yu, Hye-Ryeon; Cheong, Hae-Won

2015-02-01

Lithium-impregnated metal foam anodes (LIMFAs) are fabricated and investigated. The LIMFAs are prepared by the impregnation of lithium into molten-salt-coated nickel metal foam. A single cell with the LIMFA exhibits a specific capacity of 3009 As g-1. For comparison, a single cell with a LiSi alloy anode is also discharged, demonstrating a specific capacity of 1050 As g-1. These significant improvements can be attributed to the large amount of lithium impregnated into the metal foam as well as the molten lithium holding capability of the foam. Due to their excellent electrochemical properties, LIMFAs are suitable for use in thermal batteries.

Preparation of Ti/IrO2 Anode with Low Iridium Content by Thermal Decomposition Process: Electrochemical removal of organic pollutants in water

NASA Astrophysics Data System (ADS)

Yaqub, Asim; Isa, Mohamed Hasnain; Ajab, Huma; Kutty, S. R. M.; Ezechi, Ezerie H.; Farooq, Robina

2018-04-01

In this study IrO2 (Iridium oxide) was coated onto a titanium plate anode from a dilute (50 mg/10 ml) IrCl3×H2O salt solution. Coating was done at high temperature (550∘C) using thermal decomposition. Surface morphology and characteristics of coated surface of Ti/IrO2 anode were examined by FESEM and XRD. The coated anode was applied for electrochemical removal of organic pollutants from synthetic water samples in 100 mL compartment of batch electrochemical cell. About 50% COD removal was obtained at anode prepared with low Ir content solution while 72% COD removal was obtained with anode prepared at high Ir content. Maximum COD removal was obtained at 10 mA/cm2 current density.

Mechanism and kinetics of electrochemical degradation of uric acid using conductive-diamond anodes.

PubMed

Dbira, Sondos; Bensalah, Nasr; Bedoui, Ahmed

2016-12-01

Uric acid (UA) is one of the principal effluents of urine wastewaters, widely used in agriculture as fertilizer, which is potentially dangerous and biorefractory. Hence, the degradation of UA (2,6,8-trihydroxy purine) in aqueous solution of pH 3.0 has been studied by conductive-diamond electrochemical oxidation. Hydroxyl radicals formed from water oxidation at the surface of boron-doped diamond anodes were the main oxidizing agents. Effects of current density and supporting electrolyte on the degradation rate and process efficiency are assessed. Results show that the increase of current density from 20 to 60 mA cm(-2) leads to a decrease in the efficiency of the electrochemical process. In addition, the best degradation occurred in the presence of NaCl as conductive electrolyte. Interestingly, an almost total mineralization of 50 ppm UA was obtained when anodic oxidation was performed at low current densities (20 mA cm(-2)) and in the presence of NaCl. This result confirmed that the electrolysis using diamond anodes is a very interesting technology for the treatment of UA. The identification of UA transformation products was performed by high-performance liquid chromatography (HPLC). HPLC analysis of treated solutions revealed that oxalic acid and urea were the two intermediates found. Oxalic acid was the most persistent product. Based on detected intermediates and bibliographic research, a mechanism of UA mineralization by anodic oxidation has been proposed. Ionic chromatography analysis confirmed the release of [Formula: see text] and [Formula: see text] ions during UA mineralization.

Electrochemical synthesis of poly(pyrrole-co-o-anisidine)/chitosan composite films

NASA Astrophysics Data System (ADS)

Yalçınkaya, Süleyman; Çakmak, Didem

2017-05-01

In this study, poly(pyrrole-co-o-anisidine)/chitosan composite films were electrochemically synthesized in various monomers feed ratio (pyrrole: o-anisidine; 9:1, 7:3, 1:1, 3:7 and 1:9) of pyrrole and o-anisidine on the platinum electrode. Electrochemical synthesis of the composite films was carried out via cyclic voltammetry technique. They were characterized by FT-IR, cyclic voltammetry, SEM micrographs, digital images, TGA and DSC techniques. The SEM results indicated that the particle size of the composite decreased with increasing o-anisidine ratio and the films became more likely to be smooth morphology. The TGA results proved that the film of the composite with 1:1 ratio showed highest final degradation temperature and lowest weight loss (83%) compared to copolymer and 9:1 1:9 composite films. The 1:1 composite film had higher thermal stability than copolymer and the other composite films (9:1 1:9). Meanwhile, electrochemical studies exhibited that the 1/9 composite film had good electrochemical stability as well.

MoO x thin films deposited by magnetron sputtering as an anode for aqueous micro-supercapacitors.

PubMed

Liu, Can; Li, Zhengcao; Zhang, Zhengjun

2013-12-01

In order to examine the potential application of non-stoichiometric molybdenum oxide as anode materials for aqueous micro-supercapacitors, conductive MoO x films (2 ⩽ x ⩽ 2.3) deposited via RF magnetron sputtering at different temperatures were systematically studied for composition, structure and electrochemical properties in an aqueous solution of Li 2 SO 4 . The MoO x ( x ≈ 2.3) film deposited at 150 °C exhibited a higher areal capacitance (31 mF cm -2 measured at 5 mV s -1 ), best rate capability and excellent stability at potentials below -0.1 V versus saturated calomel electrode, compared to the films deposited at room temperature and at higher temperatures. These superior properties were attributed to the multi-valence composition and mixed-phase microstructure, i.e., the coexistence of MoO 2 nanocrystals and amorphous MoO x (2.3 < x ⩽ 3). A mechanism combining Mo(IV) oxidation/reduction on the hydrated MoO 2 grain surfaces and cation intercalation/extrusion is proposed to illustrate the pseudo-capacitive process.

Electrochemically formed 3D hierarchical thin films of cobalt-manganese (Co-Mn) hexacyanoferrate hybrids for electrochemical applications

NASA Astrophysics Data System (ADS)

Alam Venugopal, Narendra Kumar; Joseph, James

2016-02-01

Here we report the feasibility of forming 3D nanostructured hexacyanoferates of Cobalt and Manganese (Co-MnHCF) on GC surface by a facile electrochemical method. This 3D architecture on glassy carbon electrode characterised systematically by voltammetry and other physical characterisation techniques like Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform Infrared spectroscopy (FTIR) etc,. Electrochemical Quartz crystal microbalance (EQCM) studies helped out to calculate the total mass change during Co-MnHCF formation. Electrochemical studies reveal that the formal redox potentials of both Co and MnHCF films remained close to that of newly formed Co-MnHCF hybrid films. These 3D modified films were successfully applied for two different electrochemical applications i) For pseudocapacitor studies in KNO3 medium ii) Investigated the electrocatalytic behaviour of redox film towards water oxidation reaction in alkaline medium. Electrochemical performances of newly formed Co-MnHCF are compared with their individual transition metal (Co, Mn) hexacyanoferrates. The resulting material shows a specific capacitance of 350 F g-1 through its fast reversible redox reaction of electrochemically formed Co-MnHCF modified film. Interestingly we showed the overpotential of 450 mV (from its thermodynamic voltage 1.2 V) to attain its optimum current density of 10 mA cm-2 for O2 evolution in alkaline medium.

3D Microstructure Effects in Ni-YSZ Anodes: Influence of TPB Lengths on the Electrochemical Performance.

PubMed

Pecho, Omar M; Mai, Andreas; Münch, Beat; Hocker, Thomas; Flatt, Robert J; Holzer, Lorenz

2015-10-21

3D microstructure-performance relationships in Ni-YSZ anodes for electrolyte-supported cells are investigated in terms of the correlation between the triple phase boundary (TPB) length and polarization resistance ( R pol ). Three different Ni-YSZ anodes of varying microstructure are subjected to eight reduction-oxidation (redox) cycles at 950 °C. In general the TPB lengths correlate with anode performance . However, the quantitative results also show that there is no simplistic relationship between TPB and R pol . The degradation mechanism strongly depends on the initial microstructure. Finer microstructures exhibit lower degradation rates of TPB and R pol . In fine microstructures, TPB loss is found to be due to Ni coarsening, while in coarse microstructures reduction of active TPB results mainly from loss of YSZ percolation. The latter is attributed to weak bottlenecks associated with lower sintering activity of the coarse YSZ. The coarse anode suffers from complete loss of YSZ connectivity and associated drop of TPB active by 93%. Surprisingly, this severe microstructure degradation did not lead to electrochemical failure. Mechanistic scenarios are discussed for different anode microstructures. These scenarios are based on a model for coupled charge transfer and transport, which allows using TPB and effective properties as input. The mechanistic scenarios describe the microstructure influence on current distributions, which explains the observed complex relationship between TPB lengths and anode performances. The observed loss of YSZ percolation in the coarse anode is not detrimental because the electrochemical activity is concentrated in a narrow active layer. The anode performance can be predicted reliably if the volume-averaged properties (TPB active , effective ionic conductivity) are corrected for the so-called short-range effect, which is particularly important in cases with a narrow active layer.

3D Microstructure Effects in Ni-YSZ Anodes: Influence of TPB Lengths on the Electrochemical Performance

PubMed Central

Pecho, Omar M.; Mai, Andreas; Münch, Beat; Hocker, Thomas; Flatt, Robert J.; Holzer, Lorenz

2015-01-01

3D microstructure-performance relationships in Ni-YSZ anodes for electrolyte-supported cells are investigated in terms of the correlation between the triple phase boundary (TPB) length and polarization resistance (Rpol). Three different Ni-YSZ anodes of varying microstructure are subjected to eight reduction-oxidation (redox) cycles at 950 °C. In general the TPB lengths correlate with anode performance. However, the quantitative results also show that there is no simplistic relationship between TPB and Rpol. The degradation mechanism strongly depends on the initial microstructure. Finer microstructures exhibit lower degradation rates of TPB and Rpol. In fine microstructures, TPB loss is found to be due to Ni coarsening, while in coarse microstructures reduction of active TPB results mainly from loss of YSZ percolation. The latter is attributed to weak bottlenecks associated with lower sintering activity of the coarse YSZ. The coarse anode suffers from complete loss of YSZ connectivity and associated drop of TPBactive by 93%. Surprisingly, this severe microstructure degradation did not lead to electrochemical failure. Mechanistic scenarios are discussed for different anode microstructures. These scenarios are based on a model for coupled charge transfer and transport, which allows using TPB and effective properties as input. The mechanistic scenarios describe the microstructure influence on current distributions, which explains the observed complex relationship between TPB lengths and anode performances. The observed loss of YSZ percolation in the coarse anode is not detrimental because the electrochemical activity is concentrated in a narrow active layer. The anode performance can be predicted reliably if the volume-averaged properties (TPBactive, effective ionic conductivity) are corrected for the so-called short-range effect, which is particularly important in cases with a narrow active layer. PMID:28793624

Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application.

PubMed

Slaughter, Gymama; Stevens, Brian

2015-11-16

Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 mW/ cm² in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm², respectively.

Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application

PubMed Central

Slaughter, Gymama; Stevens, Brian

2015-01-01

Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 μW/ cm2 in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm2, respectively. PMID:26580661

Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates

PubMed Central

Surawathanawises, Krissada; Cheng, Xuanhong

2014-01-01

Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation. PMID:24535886

Solid state thin film battery having a high temperature lithium alloy anode

DOEpatents

Hobson, David O.

1998-01-01

An improved rechargeable thin-film lithium battery involves the provision of a higher melting temperature lithium anode. Lithium is alloyed with a suitable solute element to elevate the melting point of the anode to withstand moderately elevated temperatures.

Artificial solid electrolyte interphase to address the electrochemical degradation of silicon electrodes.

PubMed

Li, Juchuan; Dudney, Nancy J; Nanda, Jagjit; Liang, Chengdu

2014-07-09

Electrochemical degradation on silicon (Si) anodes prevents them from being successfully used in lithium (Li)-ion battery full cells. Unlike the case of graphite anodes, the natural solid electrolyte interphase (SEI) films generated from carbonate electrolytes do not self-passivate on Si, causing continuous electrolyte decomposition and loss of Li ions. In this work, we aim at solving the issue of electrochemical degradation by fabricating artificial SEI films using a solid electrolyte material, lithium phosphorus oxynitride (Lipon), which conducts Li ions and blocks electrons. For Si anodes coated with Lipon of 50 nm or thicker, a significant effect is observed in suppressing electrolyte decomposition, while Lipon of thinner than 40 nm has a limited effect. Ionic and electronic conductivity measurements reveal that the artificial SEI is effective when it is a pure ionic conductor, but electrolyte decomposition is only partially suppressed when the artificial SEI is a mixed electronic-ionic conductor. The critical thickness for this transition in conducting behavior is found to be 40-50 nm. This work provides guidance for designing artificial SEI films for high-capacity Li-ion battery electrodes using solid electrolyte materials.

Effect of S-doping on structural, optical and electrochemical properties of vanadium oxide thin films prepared by spray pyrolysis

NASA Astrophysics Data System (ADS)

Mousavi, M.; Kompany, A.; Shahtahmasebi, N.; Bagheri-Mohagheghi, M.-M.

2013-12-01

In this research, S-doped vanadium oxide thin films, with doping levels from 0 to 40 at.%, are prepared by spray pyrolysis technique on glass substrates. For electrochemical measurements, the films were deposited on florin-tin oxide coated glass substrates. The effect of S-doping on structural, electrical, optical and electrochemical properties of vanadium oxide thin films was studied. The x-ray diffractometer analysis indicated that most of the samples have cubic β-V2O5 phase structure with preferred orientation along [200]. With increase in the doping levels, the structure of the samples tends to be amorphous. The scanning electron microscopy images show that the structure of the samples is nanobelt-shaped and the width of the nanobelts decreases from nearly 100 to 40 nm with increase in the S concentration. With increase in the S-doping level, the sheet resistance and the optical band gap increase from 940 to 4015 kΩ/square and 2.41 to 2.7 eV, respectively. The cyclic voltammogram results obtained for different samples show that the undoped sample is expanded and the sample prepared at 20 at.% S-doping level has sharper anodic and cathodic peaks.

Solid state thin film battery having a high temperature lithium alloy anode

DOEpatents

Hobson, D.O.

1998-01-06

An improved rechargeable thin-film lithium battery involves the provision of a higher melting temperature lithium anode. Lithium is alloyed with a suitable solute element to elevate the melting point of the anode to withstand moderately elevated temperatures. 2 figs.

Light-weight free-standing carbon nanotube-silicon films for anodes of lithium ion batteries.

PubMed

Cui, Li-Feng; Hu, Liangbing; Choi, Jang Wook; Cui, Yi

2010-07-27

Silicon is an attractive alloy-type anode material because of its highest known capacity (4200 mAh/g). However, lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300%, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Si nanostructures such as nanowires, which are chemically and electrically bonded to the current collector, can overcome the pulverization problem, however, the heavy metal current collectors in these systems are larger in weight than Si active material. Herein we report a novel anode structure free of heavy metal current collectors by integrating a flexible, conductive carbon nanotube (CNT) network into a Si anode. The composite film is free-standing and has a structure similar to the steel bar reinforced concrete, where the infiltrated CNT network functions as both mechanical support and electrical conductor and Si as a high capacity anode material for Li-ion battery. Such free-standing film has a low sheet resistance of approximately 30 Ohm/sq. It shows a high specific charge storage capacity (approximately 2000 mAh/g) and a good cycling life, superior to pure sputtered-on silicon films with similar thicknesses. Scanning electron micrographs show that Si is still connected by the CNT network even when small breaking or cracks appear in the film after cycling. The film can also "ripple up" to release the strain of a large volume change during lithium intercalation. The conductive composite film can function as both anode active material and current collector. It offers approximately 10 times improvement in specific capacity compared with widely used graphite/copper anode sheets.

Electrochemical deposition of honeycomb magnetite on partially exfoliated graphite as anode for capacitive applications

NASA Astrophysics Data System (ADS)

Sun, Zhen; Cai, Xiang; Song, Yu; Liu, Xiao-Xia

2017-08-01

Research on anode materials with high capacitive performance is lagging behind that of cathode materials, which has severely hindered the development of high-efficient energy storage devices. Compared with other anode materials, Fe3O4 exhibits highly desirable advantages due to its low cost, high theoretical capacity and preferable electronic conductivity of ∼102 S cm-1. Herein, hierarchical honeycomb Fe3O4 is integrated on functionalized exfoliated graphite through electrochemical deposition and the following chemical conversion. The hierarchical honeycomb Fe3O4 is constructed by the oxide nanorods, which are assembled by a number of nanoparticles. This unique porous structure not only ensures fast ion diffusion in the electrode, but also provides large amount of active sites for electrochemical reactions. The exfoliated graphene atop the graphite base can act as 3D conductive scaffold to facilitate the electron transport of the electrode. Therefore, FEG/Fe3O4 exhibits large specific capacitances of 327 F g-1@1 A g-1 and 275 F g-1@10 A g-1. Good cycling stability is also achieved due to the flexibility of the graphene substrate. The assembled asymmetric device using FEG/Fe3O4 as anode can deliver a high energy density of 54 Wh kg-1.

Effects of the voltage and time of anodization on modulation of the pore dimensions of AAO films for nanomaterials synthesis

NASA Astrophysics Data System (ADS)

Chahrour, Khaled M.; Ahmed, Naser M.; Hashim, M. R.; Elfadill, Nezar G.; Maryam, W.; Ahmad, M. A.; Bououdina, M.

2015-12-01

Highly-ordered and hexagonal-shaped nanoporous anodic aluminum oxide (AAO) of 1 μm thickness of Al pre-deposited onto Si substrate using two-step anodization was successfully fabricated. The growth mechanism of the porous AAO film was investigated by anodization current-time behavior for different anodizing voltages and by visualizing the microstructural procedure of the fabrication of AAO film by two-step anodization using cross-sectional and top view of FESEM imaging. Optimum conditions of the process variables such as annealing time of the as-deposited Al thin film and pore widening time of porous AAO film were experimentally determined to obtain AAO films with uniformly distributed and vertically aligned porous microstructure. Pores with diameter ranging from 50 nm to 110 nm and thicknesses between 250 nm and 1400 nm, were obtained by controlling two main influential anodization parameters: the anodizing voltage and time of the second-step anodization. X-ray diffraction analysis reveals amorphous-to-crystalline phase transformation after annealing at temperatures above 800 °C. AFM images show optimum ordering of the porous AAO film anodized under low voltage condition. AAO films may be exploited as templates with desired size distribution for the fabrication of CuO nanorod arrays. Such nanostructured materials exhibit unique properties and hold high potential for nanotechnology devices.

Lanthanum Nitrate As Electrolyte Additive To Stabilize the Surface Morphology of Lithium Anode for Lithium-Sulfur Battery.

PubMed

Liu, Sheng; Li, Guo-Ran; Gao, Xue-Ping

2016-03-01

Lithium-sulfur (Li-S) battery is regarded as one of the most promising candidates beyond conventional lithium ion batteries. However, the instability of the metallic lithium anode during lithium electrochemical dissolution/deposition is still a major barrier for the practical application of Li-S battery. In this work, lanthanum nitrate, as electrolyte additive, is introduced into Li-S battery to stabilize the surface of lithium anode. By introducing lanthanum nitrate into electrolyte, a composite passivation film of lanthanum/lithium sulfides can be formed on metallic lithium anode, which is beneficial to decrease the reducibility of metallic lithium and slow down the electrochemical dissolution/deposition reaction on lithium anode for stabilizing the surface morphology of metallic Li anode in lithium-sulfur battery. Meanwhile, the cycle stability of the fabricated Li-S cell is improved by introducing lanthanum nitrate into electrolyte. Apparently, lanthanum nitrate is an effective additive for the protection of lithium anode and the cycling stability of Li-S battery.

CHARACTERISTICS OF ANODIC AND CORROSION FILMS ON ZIRCONIUM

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

Misch, R.D.

1960-05-01

Zirconium anodizes similarly to tungsten in respect to the change of interference colors with applied voltage. However, the oxide layer on tungsten cannot reach as great a thickness. Hafnium does not anodize in the same way as zirconium but is similar to tantalum. By measuring the interference color and capacitative thicknesses on zirconium (Grades I and III) and a 2.5 wt.% tin ailoy, the film was found to grow less rapidly in terms of capacitance than in terms of iaterference colors. This was interpreted to mean that cracks develop in the oxide as it thickens. The effect was most pronouncedmore » on Grade III zirconium and least pronounced on the tin alloy. The reduction in capacitative thickness was especially noticeable when white oxide appeared. Comparative measurements on Grade I zirconium and 2.5 wt.% tin alloy indicated that the thickness of the oxide film on the tin alloy (after 16 hours in water) increased more rapidly with temperature than the film on zirconium. Tin is believed to act in ways to counteract the tendency of the oxide to form cracks, and to produce vacancies which promote ionic diffusion. (auth)« less

Highly efficient lithium composite anode with hydrophobic molten salt in seawater

NASA Astrophysics Data System (ADS)

Zhang, Yancheng; Urquidi-Macdonald, Mirna

A lithium composite anode (lithium/1-butyl-3-methyl-imidazoleum hexafluorophosphate (BMI +PF 6-)/4-VLZ) for primary lithium/seawater semi-fuel-cells is proposed to reduce lithium-water parasitic reaction and, hence, increase the lithium anodic efficiency up to 100%. The lithium composite anode was activated when in contact with artificial seawater (3% NaCl solution) and the output was a stable anodic current density at 0.2 mA/cm 2, which lasted about 10 h under potentiostatic polarization at +0.5 V versus open circuit potential (OCP); the anodic efficiency was indirectly measured to be 100%. With time, a small traces of water diffused through the hydrophobic molten salt, BMI +PF 6-, reached the lithium interface and formed a double layer film (LiH/LiOH). Accordingly, the current density decreased and the anodic efficiency was estimated to be 90%. The hypothesis of small traces of water penetrating the molten salt and reaching the lithium anode—after several hours of operation—is supported by the collected experimental current density and hydrogen evolution, electrochemical impedance spectrum analysis, and non-mechanistic interface film modeling of lithium/BMI +PF 6-.

Morphology of the porous silicon obtained by electrochemical anodization method

NASA Astrophysics Data System (ADS)

Bertel H, S. D.; Dussán C, A.; Diaz P, J. M.

2018-04-01

In this report, the dependence of porous silicon with the synthesis parameters and their correlation with the optical and morphological properties is studied. The P-type silicon-crystalline samples and orientation <1 0 0> were prepared by electrochemical anodization and were characterized using SEM in order to know the evolution of the pore morphology. It was observed that the porosity and thickness of the samples increased with the increase of the concentration in the solution and a high pore density (70%) with a pore size between 40nm and 1.5μm.

Solid-phase electrochemical reduction of graphene oxide films in alkaline solution

NASA Astrophysics Data System (ADS)

Basirun, Wan J.; Sookhakian, Mehran; Baradaran, Saeid; Mahmoudian, Mohammad R.; Ebadi, Mehdi

2013-09-01

Graphene oxide (GO) film was evaporated onto graphite and used as an electrode to produce electrochemically reduced graphene oxide (ERGO) films by electrochemical reduction in 6 M KOH solution through voltammetric cycling. Fourier transformed infrared and Raman spectroscopy confirmed the presence of ERGO. Electrochemical impedance spectroscopy characterization of ERGO and GO films in ferrocyanide/ferricyanide redox couple with 0.1 M KCl supporting electrolyte gave results that are in accordance with previous reports. Based on the EIS results, ERGO shows higher capacitance and lower charge transfer resistance compared to GO.

Silicon-tin oxynitride glassy composition and use as anode for lithium-ion battery

DOEpatents

Neudecker, Bernd J.; Bates, John B.

2001-01-01

Disclosed are silicon-tin oxynitride glassy compositions which are especially useful in the construction of anode material for thin-film electrochemical devices including rechargeable lithium-ion batteries, electrochromic mirrors, electrochromic windows, and actuators. Additional applications of silicon-tin oxynitride glassy compositions include optical fibers and optical waveguides.

Influence of surfactants on the microstructure and electrochemical performance of the tin oxide anode in lithium ion batteries

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

Sun, Yan-Hui, E-mail: sunyanhui0102@163.com; Guangzhou Key Laboratory of Materials for Energy Conversion and Storage, South China Normal University, Guangzhou 510006; Dong, Pei-Pei

2016-02-15

Highlights: • CTAB and SDS alter the formation of SnO{sub 2} from nanosheets to nanocubes during oxalate precipitation. • The CTAB concentration affects the SnO{sub 2} crystal growth direction, morphology and size. • The SnO{sub 2} anode synthesized using CTAB exhibited superior electrochemical performance. • Proposed a mechanism of influence of surfactant on SnO{sub 2} in the precipitation and annealing process. - Abstract: Different SnO{sub 2} micro–nano structures are prepared by precipitation using a surfactant-assisted process. The surfactants, such as cetyltriethylammonium bromide (CTAB) or sodium dodecyl benzene sulfonate (SDBS), can change the crystal growth direction and microstructure of SnO{sub 2}more » primary and secondary particles. Larger SnO{sub 2} nanosheets were synthesized without surfactant, and micro-fragments composed of small nanospheres or nanocubes were synthesized using CTAB and SDBS. The CTAB-assisted process resulted in smaller primary particles and larger specific surface area and larger pore volume, as a lithium-ion-battery anode that exhibits superior electrochemical performance compared to the other two anodes. Further investigation showed that the concentration of CTAB had a substantial influence on the growth of the crystal face, morphology and size of the SnO{sub 2} secondary particles, which influenced the electrochemical performance of the anode. A simple mechanism for the influence of surfactants on SnO{sub 2} morphology and size in the precipitation and annealing process is proposed.« less

Silicon Based Anodes for Li-Ion Batteries

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

Zhang, Jiguang; Wang, Wei; Xiao, Jie

2012-06-15

Silicon is environmentally benign and ubiquitous. Because of its high specific capacity, it is considered one of the most promising candidates to replace the conventional graphite negative electrode used in today's Li ion batteries. Silicon has a theoretical specific capacity of nearly 4200 mAh/g (Li21Si5), which is 10 times larger than the specific capacity of graphite (LiC6, 372 mAh/g). However, the high capacity of silicon is associated with huge volume changes (more than 300 percent) when alloyed with lithium, which can cause severe cracking and pulverization of the electrode and lead to significant capacity loss. Significant scientific research has beenmore » conducted to circumvent the deterioration of silicon based anode materials during cycling. Various strategies, such as reduction of particle size, generation of active/inactive composites, fabrication of silicon based thin films, use of alternative binders, and the synthesis of 1-D silicon nanostructures have been implemented by a number of research groups. Fundamental mechanistic research has also been performed to better understand the electrochemical lithiation and delithiation process during cycling in terms of crystal structure, phase transitions, morphological changes, and reaction kinetics. Although efforts to date have not attained a commercially viable Si anode, further development is expected to produce anodes with three to five times the capacity of graphite. In this chapter, an overview of research on silicon based anodes used for lithium-ion battery applications will be presented. The overview covers electrochemical alloying of the silicon with lithium, mechanisms responsible for capacity fade, and methodologies adapted to overcome capacity degradation observed during cycling. The recent development of silicon nanowires and nanoparticles with significantly improved electrochemical performance will also be discussed relative to the mechanistic understanding. Finally, future directions on the

The effect of solution pH on the electrochemical performance of nanocrystalline metal ferrites MFe2O4 (M=Cu, Zn, and Ni) thin films

NASA Astrophysics Data System (ADS)

Elsayed, E. M.; Rashad, M. M.; Khalil, H. F. Y.; Ibrahim, I. A.; Hussein, M. R.; El-Sabbah, M. M. B.

2016-04-01

Nanocrystalline metal ferrite MFe2O4 (M=Cu, Zn, and Ni) thin films have been synthesized via electrodeposition-anodization process. Electrodeposited (M)Fe2 alloys were obtained from aqueous sulfate bath. The formed alloys were electrochemically oxidized (anodized) in aqueous (1 M KOH) solution, at room temperature, to the corresponding hydroxides. The parameters controlling the current efficiency of the electrodeposition of (M)Fe2 alloys such as the bath composition and the current density were studied and optimized. The anodized (M)Fe2 alloy films were annealed in air at 400 °C for 2 h. The results revealed the formation of three ferrite thin films were formed. The crystallite sizes of the produced films were in the range between 45 and 60 nm. The microstructure of the formed film was ferrite type dependent. The corrosion behavior of ferrite thin films in different pH solutions was investigated using open circuit potential (OCP) and potentiodynamic polarization measurements. The open circuit potential indicates that the initial potential E im of ZnFe2O4 thin films remained constant for a short time, then sharply increased in the less negative direction in acidic and alkaline medium compared with Ni and Cu ferrite films. The values of the corrosion current density I corr were higher for the ZnFe2O4 films at pH values of 1 and 12 compared with that of NiFe2O4 and CuFe2O4 which were higher only at pH value 1. The corrosion rate was very low for the three ferrite films when immersion in the neutral medium. The surface morphology recommended that Ni and Cu ferrite films were safely used in neutral and alkaline medium, whereas Zn ferrite film was only used in neutral atmospheres.

Artificial Solid Electrolyte Interphase to Address the Electrochemical Degradation of Silicon Electrodes

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

Dudney, Nancy J; Nanda, Jagjit; Liang, Chengdu

2014-01-01

Electrochemical degradation on Si anodes prevents them from being successfully used in lithium-ion full cells. Unlike the case of graphite anodes, natural solid electrolyte interphase (SEI) films generated from carbonate electrolyte do not self-passivate on Si and causes continuous electrolyte decomposition. In this work we aim at solving the issue of electrochemical degradation by fabricating artificial SEI films using a solid electrolyte material, lithium phosphor oxynitride (Lipon), that conducts Li ions and blocks electrons. For Si anodes coated with Lipon of 50 nm or thicker, significant effect is observed in suppressing the electrolyte decomposition, while Lipon of thinner than 40more » nm has little effect. Ionic and electronic conductivity measurement reveals that the artificial SEI is effective when it is a pure ionic conductor, and the electrolyte decomposition is not suppressed when the artificial SEI is a mixed electronic-ionic conductor. The critical thickness for this transition in conducting behavior is found to be 40~50 nm. This work provides guidance for designing artificial SEI for high capacity lithium-ion battery electrodes using solid electrolyte materials.« less

Electrochemical decolorization of dye wastewater by surface-activated boron-doped nanocrystalline diamond electrode.

PubMed

Chen, Chienhung; Nurhayati, Ervin; Juang, Yaju; Huang, Chihpin

2016-07-01

Complex organics contained in dye wastewater are difficult to degrade and often require electrochemical advanced oxidation processes (EAOPs) to treat it. Surface activation of the electrode used in such treatment is an important factor determining the success of the process. The performance of boron-doped nanocrystalline diamond (BD-NCD) film electrode for decolorization of Acid Yellow (AY-36) azo dye with respect to the surface activation by electrochemical polarization was studied. Anodic polarization found to be more suitable as electrode pretreatment compared to cathodic one. After anodic polarization, the originally H-terminated surface of BD-NCD was changed into O-terminated, making it more hydrophilic. Due to the oxidation of surface functional groups and some portion of sp(2) carbon in the BD-NCD film during anodic polarization, the electrode was successfully being activated showing lower background current, wider potential window and considerably less surface activity compared to the non-polarized one. Consequently, electrooxidation (EO) capability of the anodically-polarized BD-NCD to degrade AY-36 dye was significantly enhanced, capable of nearly total decolorization and chemical oxygen demand (COD) removal even after several times of re-using. The BD-NCD film electrode favored acidic condition for the dye degradation; and the presence of chloride ion in the solution was found to be more advantageous than sulfate active species. Copyright © 2016. Published by Elsevier B.V.

Auger electron spectroscopy and Rutherford backscattering studies of copper in 2024-T3 aluminum following electrochemical anodization in phosphoric acid

NASA Astrophysics Data System (ADS)

Solomon, J. S.

1981-05-01

The effects of the electrochemical anodization of dioxidized 2024-T3 aluminum on copper were characterized by Auger electron spectroscopy and Rutherford backscattering. Anodization was performed in phosphoric acid at constant potential. Data is presented which shows that constant potential anodization of 2024-T3 is more efficient than aluminum in terms of oxide growth rates for short anodization times. However the maximum anodic oxide thickness achievable on the alloy is less than the pure metal. Copper is shown to be enriched at the oxide metal interface because of its diffusion from the bulk during anodization. The presence of copper at the oxide-metal interface is shown to affect oxide morphology.

Using sewage sludge pyrolytic gas to modify titanium alloy to obtain high-performance anodes in bio-electrochemical systems

NASA Astrophysics Data System (ADS)

Gu, Yuan; Ying, Kang; Shen, Dongsheng; Huang, Lijie; Ying, Xianbin; Huang, Haoqian; Cheng, Kun; Chen, Jiazheng; Zhou, Yuyang; Chen, Ting; Feng, Huajun

2017-12-01

Titanium is under consideration as a potential stable bio-anode because of its high conductivity, suitable mechanical properties, and electrochemical inertness in the operating potential window of bio-electrochemical systems; however, its application is limited by its poor electron-transfer capacity with electroactive bacteria and weak ability to form biofilms on its hydrophobic surface. This study reports an effective and low-cost way to convert a hydrophobic titanium alloy surface into a hydrophilic surface that can be used as a bio-electrode with higher electron-transfer rates. Pyrolytic gas of sewage sludge is used to modify the titanium alloy. The current generation, anodic biofilm formation surface, and hydrophobicity are systematically investigated by comparing bare electrodes with three modified electrodes. Maximum current density (15.80 A/m2), achieved using a modified electrode, is 316-fold higher than that of the bare titanium alloy electrode (0.05 A/m2) and that achieved by titanium alloy electrodes modified by other methods (12.70 A/m2). The pyrolytic gas-modified titanium alloy electrode can be used as a high-performance and scalable bio-anode for bio-electrochemical systems because of its high electron-transfer rates, hydrophilic nature, and ability to achieve high current density.

Investigation of the mechanical and chemical characteristics of nanotubular and nano-pitted anodic films on grade 2 titanium dental implant materials.

PubMed

Weszl, Miklós; Tóth, Krisztián László; Kientzl, Imre; Nagy, Péter; Pammer, Dávid; Pelyhe, Liza; Vrana, Nihal E; Scharnweber, Dieter; Wolf-Brandstetter, Cornelia; Joób F, Árpád; Bognár, Eszter

2017-09-01

The objective of this study was to investigate the reproducibility, mechanical integrity, surface characteristics and corrosion behavior of nanotubular (NT) titanium oxide arrays in comparison with a novel nano-pitted (NP) anodic film. Surface treatment processes were developed to grow homogenous NT and NP anodic films on the surface of grade 2 titanium discs and dental implants. The effect of process parameters on the surface characteristics and reproducibility of the anodic films was investigated and optimized. The mechanical integrity of the NT and NP anodic films were investigated by scanning electron microscopy, surface roughness measurement, scratch resistance and screwing tests, while the chemical and physicochemical properties were investigated in corrosion tests, contact angle measurement and X-ray photoelectron spectroscopy (XPS). The growth of NT anodic films was highly affected by process parameters, especially by temperature, and they were apt to corrosion and exfoliation. In contrast, the anodic growth of NP film showed high reproducibility even on the surface of 3-dimensional screw dental implants and they did not show signs of corrosion and exfoliation. The underlying reason of the difference in the tendency for exfoliation of the NT and NP anodic films is unclear; however the XPS analysis revealed fluorine dopants in a magnitude larger concentration on NT anodic film than on NP surface, which was identified as a possible causative. Concerning other surface characteristics that are supposed to affect the biological behavior of titanium implants, surface roughness values were found to be similar, whereas considerable differences were revealed in the wettability of the NT and NP anodic films. Our findings suggest that the applicability of NT anodic films on the surface of titanium bone implants may be limited because of mechanical considerations. In contrast, it is worth to consider the applicability of nano-pitted anodic films over nanotubular arrays

Dual-Layered Film Protected Lithium Metal Anode to Enable Dendrite-Free Lithium Deposition.

PubMed

Yan, Chong; Cheng, Xin-Bing; Tian, Yang; Chen, Xiang; Zhang, Xue-Qiang; Li, Wen-Jun; Huang, Jia-Qi; Zhang, Qiang

2018-06-01

Lithium metal batteries (such as lithium-sulfur, lithium-air, solid state batteries with lithium metal anode) are highly considered as promising candidates for next-generation energy storage systems. However, the unstable interfaces between lithium anode and electrolyte definitely induce the undesired and uncontrollable growth of lithium dendrites, which results in the short-circuit and thermal runaway of the rechargeable batteries. Herein, a dual-layered film is built on a Li metal anode by the immersion of lithium plates into the fluoroethylene carbonate solvent. The ionic conductive film exhibits a compact dual-layered feature with organic components (ROCO 2 Li and ROLi) on the top and abundant inorganic components (Li 2 CO 3 and LiF) in the bottom. The dual-layered interface can protect the Li metal anode from the corrosion of electrolytes and regulate the uniform deposition of Li to achieve a dendrite-free Li metal anode. This work demonstrates the concept of rational construction of dual-layered structured interfaces for safe rechargeable batteries through facile surface modification of Li metal anodes. This not only is critically helpful to comprehensively understand the functional mechanism of fluoroethylene carbonate but also affords a facile and efficient method to protect Li metal anodes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical Oxidation of Resorcinol in Aqueous Medium Using Boron-Doped Diamond Anode: Reaction Kinetics and Process Optimization with Response Surface Methodology

PubMed Central

Körbahti, Bahadır K.; Demirbüken, Pelin

2017-01-01

Electrochemical oxidation of resorcinol in aqueous medium using boron-doped diamond anode (BDD) was investigated in a batch electrochemical reactor in the presence of Na2SO4 supporting electrolyte. The effect of process parameters such as resorcinol concentration (100–500 g/L), current density (2–10 mA/cm2), Na2SO4 concentration (0–20 g/L), and reaction temperature (25–45°C) was analyzed on electrochemical oxidation using response surface methodology (RSM). The optimum operating conditions were determined as 300 mg/L resorcinol concentration, 8 mA/cm2 current density, 12 g/L Na2SO4 concentration, and 34°C reaction temperature. One hundred percent of resorcinol removal and 89% COD removal were obtained in 120 min reaction time at response surface optimized conditions. These results confirmed that the electrochemical mineralization of resorcinol was successfully accomplished using BDD anode depending on the process conditions, however the formation of intermediates and by-products were further oxidized at much lower rate. The reaction kinetics were evaluated at optimum conditions and the reaction order of electrochemical oxidation of resorcinol in aqueous medium using BDD anode was determined as 1 based on COD concentration with the activation energy of 5.32 kJ/mol that was supported a diffusion-controlled reaction. PMID:29082225

MnO2 prepared by hydrothermal method and electrochemical performance as anode for lithium-ion battery.

PubMed

Feng, Lili; Xuan, Zhewen; Zhao, Hongbo; Bai, Yang; Guo, Junming; Su, Chang-Wei; Chen, Xiaokai

2014-01-01

Two α-MnO2 crystals with caddice-clew-like and urchin-like morphologies are prepared by the hydrothermal method, and their structure and electrochemical performance are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), galvanostatic cell cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The morphology of the MnO2 prepared under acidic condition is urchin-like, while the one prepared under neutral condition is caddice-clew-like. The identical crystalline phase of MnO2 crystals is essential to evaluate the relationship between electrochemical performances and morphologies for lithium-ion battery application. In this study, urchin-like α-MnO2 crystals with compact structure have better electrochemical performance due to the higher specific capacity and lower impedance. We find that the relationship between electrochemical performance and morphology is different when MnO2 material used as electrochemical supercapacitor or as anode of lithium-ion battery. For lithium-ion battery application, urchin-like MnO2 material has better electrochemical performance.

Thin film integrated capacitors with sputtered-anodized niobium pentoxide dielectric for decoupling applications

NASA Astrophysics Data System (ADS)

Jacob, Susan

Electronics system miniaturization is a major driver for high-k materials. High-k materials in capacitors allow for high capacitance, enabling system miniaturization. Ta2O5 (k˜24) has been the dominant high-k material in the electronic industry for decoupling capacitors, filter capacitors, etc. In order to facilitate further system miniaturization, this project has investigated thin film integrated capacitors with Nb2O5 dielectric. Nb2O 5 has k˜41 and is a potential candidate for replacing Ta2O5. But, the presence of suboxides (NbO2 and NbO) in the dielectric deteriorates the electrical properties (leakage current, thermal instability of capacitance, etc.). Also, the high oxygen solubility of niobium results in oxygen diffusion from the dielectric to niobium metal, if any is present. The major purpose of this project was to check the ability of NbN as a diffusion barrier and fabricate thermally stable niobium capacitors. As a first step to produce niobium capacitors, the material characterizations of reactively sputtered Nb2O5 and NbN were done. Thickness and film composition, and crystal structures of the sputtered films were obtained and the deposition parameters for the desired stoichiometry were found. Also, anodized Nb2O5 was characterized for its stoichiometry and thickness. To study the effect of nitrides on capacitance and thermal stability, Ta2O5 capacitors were initially fabricated with and without TaN. The results showed that the nitride does not affect the capacitance, and that capacitors with TaN are stable up to 150°C. In the next step, niobium capacitors were first fabricated with anodized dielectric and the oxygen diffusion issues associated with capacitor processing were studied. Reactively sputtered Nb2O5 was anodized to form complete Nb2O5 (with few oxygen vacancies) and NbN was used to sandwich the dielectric. The capacitor fabrication was not successful due to the difficulties in anodizing the sputtered dielectric. Another method, anodizing

Microbial Communities and Electrochemical Performance of Titanium-Based Anodic Electrodes in a Microbial Fuel Cell▿

PubMed Central

Michaelidou, Urania; ter Heijne, Annemiek; Euverink, Gerrit Jan W.; Hamelers, Hubertus V. M.; Stams, Alfons J. M.; Geelhoed, Jeanine S.

2011-01-01

Four types of titanium (Ti)-based electrodes were tested in the same microbial fuel cell (MFC) anodic compartment. Their electrochemical performances and the dominant microbial communities of the electrode biofilms were compared. The electrodes were identical in shape, macroscopic surface area, and core material but differed in either surface coating (Pt- or Ta-coated metal composites) or surface texture (smooth or rough). The MFC was inoculated with electrochemically active, neutrophilic microorganisms that had been enriched in the anodic compartments of acetate-fed MFCs over a period of 4 years. The original inoculum consisted of bioreactor sludge samples amended with Geobacter sulfurreducens strain PCA. Overall, the Pt- and Ta-coated Ti bioanodes (electrode-biofilm association) showed higher current production than the uncoated Ti bioanodes. Analyses of extracted DNA of the anodic liquid and the Pt- and Ta-coated Ti electrode biofilms indicated differences in the dominant bacterial communities. Biofilm formation on the uncoated electrodes was poor and insufficient for further analyses. Bioanode samples from the Pt- and Ta-coated Ti electrodes incubated with Fe(III) and acetate showed several Fe(III)-reducing bacteria, of which selected species were dominant, on the surface of the electrodes. In contrast, nitrate-enriched samples showed less diversity, and the enriched strains were not dominant on the electrode surface. Isolated Fe(III)-reducing strains were phylogenetically related, but not all identical, to Geobacter sulfurreducens strain PCA. Other bacterial species were also detected in the system, such as a Propionicimonas-related species that was dominant in the anodic liquid and Pseudomonas-, Clostridium-, Desulfovibrio-, Azospira-, and Aeromonas-related species. PMID:21131513

Anodic iridium oxide films: An UPS study of emersed electrodes

NASA Astrophysics Data System (ADS)

Kötz, E. R.; Neff, H.

1985-09-01

Formation of anodic iridium oxide films has been monitored using Ultraviolet Photoemission Spectroscopy (UPS) of the emersed electrodes. The potential dependent valence band spectra clearly show the onset of oxide formation at about 0.6 V versus SCE. The density of states at the Fermi level and the positron of the Fermi level with respect to the maximum of the t 2g band of the oxide indicates a transition from metallic to semiconducting behaviour of the oxide. Protonation of the oxide is associated with increased emission from OH species. A linear correlation between electrode potential and workfunction change is observed for the metal as well as for the oxide. Our results confirm known band theory models and provide a fundamental understanding of the electrochromism of anodic iridium oxide films.

Reversible superconductor-insulator transition in LiTi2O4 induced by Li-ion electrochemical reaction

PubMed Central

Yoshimatsu, K.; Niwa, M.; Mashiko, H.; Oshima, T.; Ohtomo, A.

2015-01-01

Transition metal oxides display various electronic and magnetic phases such as high-temperature superconductivity. Controlling such exotic properties by applying an external field is one of the biggest continuous challenges in condensed matter physics. Here, we demonstrate clear superconductor-insulator transition of LiTi2O4 films induced by Li-ion electrochemical reaction. A compact electrochemical cell of pseudo-Li-ion battery structure is formed with a superconducting LiTi2O4 film as an anode. Li content in the film is controlled by applying a constant redox voltage. An insulating state is achieved by Li-ion intercalation to the superconducting film by applying reduction potential. In contrast, the superconducting state is reproduced by applying oxidation potential to the Li-ion intercalated film. Moreover, superconducting transition temperature is also recovered after a number of cycles of Li-ion electrochemical reactions. This complete reversible transition originates in difference in potentials required for deintercalation of initially contained and electrochemically intercalated Li+ ions. PMID:26541508

Reversible superconductor-insulator transition in LiTi2O4 induced by Li-ion electrochemical reaction.

PubMed

Yoshimatsu, K; Niwa, M; Mashiko, H; Oshima, T; Ohtomo, A

2015-11-06

Transition metal oxides display various electronic and magnetic phases such as high-temperature superconductivity. Controlling such exotic properties by applying an external field is one of the biggest continuous challenges in condensed matter physics. Here, we demonstrate clear superconductor-insulator transition of LiTi2O4 films induced by Li-ion electrochemical reaction. A compact electrochemical cell of pseudo-Li-ion battery structure is formed with a superconducting LiTi2O4 film as an anode. Li content in the film is controlled by applying a constant redox voltage. An insulating state is achieved by Li-ion intercalation to the superconducting film by applying reduction potential. In contrast, the superconducting state is reproduced by applying oxidation potential to the Li-ion intercalated film. Moreover, superconducting transition temperature is also recovered after a number of cycles of Li-ion electrochemical reactions. This complete reversible transition originates in difference in potentials required for deintercalation of initially contained and electrochemically intercalated Li(+) ions.

An Analysis of Mechanical Properties of Anodized Aluminum Film at High Stress

NASA Astrophysics Data System (ADS)

Zhao, Xixi; Wei, Guoying; Yu, Yundan; Guo, Yuemei; Zhang, Ao

2015-10-01

In this paper, a new environmental-friendly electrolyte containing sulfuric acid and tartaric acid has been used as the substitute of chromic acid for anodization. The work discussed the influence of anodizing voltages on the fatigue life of anodized Al 2024-T3 by performing fatigue tests with 0.1 stress ratio (R) at 320 MPa. Meanwhile the fatigue cycles to failure, yield strength, tensile strength and fracture surface of anodic films at different conditions were investigated. The results showed that the fatigue life of anodized and sealed specimens reduced a lot compared to aluminum alloy, which can be attributed to the crack sites initiated at the oxide layer. The fracture surface analyses also revealed that the number of crack initiation sites enlarged with the increase of anodizing voltage.

Ultrahigh-Performance Cu2ZnSnS4 Thin Film and Its Application in Microscale Thin-Film Lithium-Ion Battery: Comparison with SnO2.

PubMed

Lin, Jie; Guo, Jianlai; Liu, Chang; Guo, Hang

2016-12-21

To develop a high-performance anode for thin-film lithium-ion batteries (TFBs, with a total thickness on the scale of micrometers), a Cu 2 ZnSnS 4 (CZTS) thin film is fabricated by magnetron sputtering and exhibits an ultrahigh performance of 950 mAh g -1 even after 500 cycles, which is the highest among the reported CZTS for lithium storage so far. The characterization and electrochemical tests reveal that the thin-film structure and additional reactions both contribute to the excellent properties. Furthermore, the microscale TFBs with effective footprints of 0.52 mm 2 utilizing the CZTS thin film as anode are manufactured by microfabrication techniques, showing superior capability than the analogous TFBs with the SnO 2 thin film as anode. This work demonstrates the advantages of exploiting thin-film electrodes and novel materials into micropower sources by electronic manufacture methods.

The effects of anode material type on the optoelectronic properties of electroplated CdTe thin films and the implications for photovoltaic application

NASA Astrophysics Data System (ADS)

Echendu, O. K.; Dejene, B. F.; Dharmadasa, I. M.

2018-03-01

The effects of the type of anode material on the properties of electrodeposited CdTe thin films for photovoltaic application have been studied. Cathodic electrodeposition of two sets of CdTe thin films on glass/fluorine-doped tin oxide (FTO) was carried out in two-electrode configuration using graphite and platinum anodes. Optical absorption spectra of films grown with graphite anode displayed significant spread across the deposition potentials compared to those grown with platinum anode. Photoelectrochemical cell result shows that the CdTe grown with graphite anode became p-type after post-deposition annealing with prior CdCl2 treatment, as a result of carbon incorporation into the films, while those grown with platinum anode remained n-type after annealing. A review of recent photoluminescence characterization of some of these CdTe films reveals the persistence of a defect level at (0.97-0.99) eV below the conduction band in the bandgap of CdTe grown with graphite anode after annealing while films grown with platinum anode showed the absence of this defect level. This confirms the impact of carbon incorporation into CdTe. Solar cell made with CdTe grown with platinum anode produced better conversion efficiency compared to that made with CdTe grown using graphite anode, underlining the impact of anode type in electrodeposition.

Modelling the growth process of porous aluminum oxide film during anodization

NASA Astrophysics Data System (ADS)

Aryslanova, E. M.; Alfimov, A. V.; Chivilikhin, S. A.

2015-11-01

Currently it has become important for the development of metamaterials and nanotechnology to obtain regular self-assembled structures. One such structure is porous anodic alumina film that consists of hexagonally packed cylindrical pores. In this work we consider the anodization process, our model takes into account the influence of layers of aluminum and electrolyte on the rate of growth of aluminum oxide, as well as the effect of surface diffusion. In present work we consider those effects. And as a result of our model we obtain the minimum distance between centers of alumina pores in the beginning of anodizing process.

In situ detection of porosity initiation during aluminum thin film anodizing

NASA Astrophysics Data System (ADS)

Van Overmeere, Quentin; Nysten, Bernard; Proost, Joris

2009-02-01

High-resolution curvature measurements have been performed in situ during aluminum thin film anodizing in sulfuric acid. A well-defined transition in the rate of internal stress-induced curvature change is shown to allow for the accurate, real-time detection of porosity initiation. The validity of this in situ diagnostic tool was confirmed by a quantitative analysis of the spectral density distributions of the anodized surfaces. These were obtained by analyzing ex situ atomic force microscopy images of surfaces anodized for different times, and allowed to correlate the in situ detected transition in the rate of curvature change with the appearance of porosity.

Effect of anodization on the surface characteristics and electrochemical behaviour of zirconium in artificial saliva.

PubMed

Romonti, Daniela E; Gomez Sanchez, Andrea V; Milošev, Ingrid; Demetrescu, Ioana; Ceré, Silvia

2016-05-01

The paper is focused on elaboration of ZrO2 films on pure zirconium via anodizing in phosphoric acid with and without fluoride at constant potentials of 30 V and 60 V. The structure and composition of the films were investigated using scanning electronic microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The composition of the oxides formed at both potentials can be identified as monoclinic ZrO2. In addition to Zr and O, the layers formed in phosphoric acid contain phosphorus originating from the phosphoric acid. When the phosphoric acid solution contains NaF, fluorine is also incorporated into the oxide layer. The oxides formed at a higher voltage have greater roughness than those formed at 30 V. Anodized samples exhibit smaller current densities during anodic polarization compared to the as-received zirconium covered with native oxide. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes

NASA Astrophysics Data System (ADS)

Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

2016-02-01

We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials.

Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes

PubMed Central

Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

2016-01-01

We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials. PMID:26831759

Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes.

PubMed

Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

2016-02-02

We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials.

Synthesis and characterization of nanoporous anodic oxide film on aluminum in H3PO4 + KMnO4 electrolyte mixture at different anodization conditions

NASA Astrophysics Data System (ADS)

Verma, Naveen; Jindal, Jitender; Singh, Krishan Chander; Mari, Bernabe

2016-04-01

The micro structural properties of nanoporous anodic oxide film formed in H3PO4 were highly influenced by addition of a low concentration of KMnO4 (0.0005 M) in 1 M H3PO4 solution. The KMnO4 as additive enhanced the growth rate of oxide film formation as well as thickness of pore walls. Furthermore the growth rate was found increased with increase in applied current density. The increase in temperature and lack of stirring during anodization causes the thinness of pore wall which leads to increase in pore volume. With the decrease in concentration of H3PO4 in anodizing electrolyte from 1M to 0.3 M, keeping all other conditions constant, the decrease in porosity was observed. This might be due to the dissolution of aluminium oxide film in highly concentrated acidic solution.

Multilayered films of cobalt oxyhydroxide nanowires/manganese oxide nanosheets for electrochemical capacitor

NASA Astrophysics Data System (ADS)

Zheng, Huajun; Tang, Fengqiu; Lim, Melvin; Mukherji, Aniruddh; Yan, Xiaoxia; Wang, Lianzhou; (Max) Lu, Gao Qing

Multilayered films of cobalt oxyhydroxide nanowires (CoOOHNW) and exfoliated manganese oxide nanosheet (MONS) are fabricated by potentiostatic deposition and electrostatic self-assembly on indium-tin oxide coated glass substrates. The morphology and chemical composition of these films are characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS) and the potential application as electrochemical supercapacitors are investigated using cyclic voltammetry and charge-discharge measurements. These ITO/CoOOHNW/MONS multilayered film electrodes exhibit excellent electrochemical capacitance properties, including high specific capacitance (507 F g -1) and long cycling durability (less 2% capacity loss after 5000 charge/discharge cycles). These characteristics indicate that these newly developed films may find important application for electrochemical capacitors.

Anodic Oxidation in Aluminum Electrode by Using Hydrated Amorphous Aluminum Oxide Film as Solid Electrolyte under High Electric Field.

PubMed

Yao, Manwen; Chen, Jianwen; Su, Zhen; Peng, Yong; Zou, Pei; Yao, Xi

2016-05-04

Dense and nonporous amorphous aluminum oxide (AmAO) film was deposited onto platinized silicon substrate by sol-gel and spin coating technology. The evaporated aluminum film was deposited onto the AmAO film as top electrode. The hydrated AmAO film was utilized as a solid electrolyte for anodic oxidation of the aluminum electrode (Al) film under high electric field. The hydrated AmAO film was a high efficiency electrolyte, where a 45 nm thick Al film was anodized completely on a 210 nm thick hydrated AmAO film. The current-voltage (I-V) characteristics and breakdown phenomena of a dry and hydrated 210 nm thick AmAO film with a 150 nm thick Al electrode pad were studied in this work. Breakdown voltage of the dry and hydrated 210 nm thick AmAO film were 85 ± 3 V (405 ± 14 MV m(-1)) and 160 ± 5 V (762 ± 24 MV m(-1)), respectively. The breakdown voltage of the hydrated AmAO film increased about twice, owing to the self-healing behavior (anodic oxidation reaction). As an intuitive phenomenon of the self-healing behavior, priority anodic oxidation phenomena was observed in a 210 nm thick hydrated AmAO film with a 65 nm thick Al electrode pad. The results suggested that self-healing behavior (anodic oxidation reaction) was occurring nearby the defect regions of the films during I-V test. It was an effective electrical self-healing method, which would be able to extend to many other simple and complex oxide dielectrics and various composite structures.

Effect of alloying elements Al and Ca on corrosion resistance of plasma anodized Mg alloys

NASA Astrophysics Data System (ADS)

Anawati, Asoh, Hidetaka; Ono, Sachiko

2016-04-01

Plasma anodizing is a surface treatment used to form a ceramic-type oxide film on Mg alloys by the application of a high anodic voltage to create intense plasma near the metal surface. With proper selection of the process parameters, the technique can produce high quality oxide with superior adhesion, corrosion resistance, micro-hardness, wear resistance and strength. The effect of alloying element Al on plasma anodizing process of Mg alloys was studied by comparing the anodizing curves of pure Mg, AZ31, and AZ61 alloys while the effect of Ca were studied on AZ61 alloys containing 0, 1, and 2 wt% Ca. Anodizing was performed in 0.5 M Na3PO4 solution at a constant current density of 200 Am-2 at 25°C. Anodic oxide films with lava-like structure having mix composition of amorphous and crystal were formed on all of the alloys. The main crystal form of the oxide was Mg3(PO4)2 as analyzed by XRD. Alloying elements Al and Ca played role in modifying the plasma lifetime during anodization. Al tended to extend the strong plasma lifetime and therefore accelerated the film thickening. The effect of Ca on anodizing process was still unclear. The anodic film thickness and chemical composition were altered by the presence of Ca in the alloys. Electrochemical corrosion test in 0.9% NaCl solution showed that the corrosion behavior of the anodized specimens depend on the behavior of the substrate. Increasing Al and Ca content in the alloys tended to increase the corrosion resistance of the specimens. The corrosion resistance of the anodized specimens improved significantly about two orders of magnitude relative to the bare substrate.

Two-Step Cycle for Producing Multiple Anodic Aluminum Oxide (AAO) Films with Increasing Long-Range Order

PubMed Central

2017-01-01

Nanoporous anodic aluminum oxide (AAO) membranes are being used for an increasing number of applications. However, the original two-step anodization method in which the first anodization is sacrificial to pre-pattern the second is still widely used to produce them. This method provides relatively low throughput and material utilization as half of the films are discarded. An alternative scheme that relies on alternating anodization and cathodic delamination is demonstrated that allows for the fabrication of several AAO films with only one sacrificial layer thus greatly improving total aluminum to alumina yield. The thickness for which the cathodic delamination performs best to yield full, unbroken AAO sheets is around 85 μm. Additionally, an image analysis method is used to quantify the degree of long-range ordering of the unit cells in the AAO films which was found to increase with each successive iteration of the fabrication cycle. PMID:28630684

Two-Step Cycle for Producing Multiple Anodic Aluminum Oxide (AAO) Films with Increasing Long-Range Order.

PubMed

Choudhary, Eric; Szalai, Veronika

2016-01-01

Nanoporous anodic aluminum oxide (AAO) membranes are being used for an increasing number of applications. However, the original two-step anodization method in which the first anodization is sacrificial to pre-pattern the second is still widely used to produce them. This method provides relatively low throughput and material utilization as half of the films are discarded. An alternative scheme that relies on alternating anodization and cathodic delamination is demonstrated that allows for the fabrication of several AAO films with only one sacrificial layer thus greatly improving total aluminum to alumina yield. The thickness for which the cathodic delamination performs best to yield full, unbroken AAO sheets is around 85 μm. Additionally, an image analysis method is used to quantify the degree of long-range ordering of the unit cells in the AAO films which was found to increase with each successive iteration of the fabrication cycle.

MnO2 prepared by hydrothermal method and electrochemical performance as anode for lithium-ion battery

PubMed Central

2014-01-01

Two α-MnO2 crystals with caddice-clew-like and urchin-like morphologies are prepared by the hydrothermal method, and their structure and electrochemical performance are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), galvanostatic cell cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The morphology of the MnO2 prepared under acidic condition is urchin-like, while the one prepared under neutral condition is caddice-clew-like. The identical crystalline phase of MnO2 crystals is essential to evaluate the relationship between electrochemical performances and morphologies for lithium-ion battery application. In this study, urchin-like α-MnO2 crystals with compact structure have better electrochemical performance due to the higher specific capacity and lower impedance. We find that the relationship between electrochemical performance and morphology is different when MnO2 material used as electrochemical supercapacitor or as anode of lithium-ion battery. For lithium-ion battery application, urchin-like MnO2 material has better electrochemical performance. PMID:24982603

Influence of square wave anodization on the electronic properties and structures of the passive films on Ti in sulfuric acid solution

NASA Astrophysics Data System (ADS)

Long, Y.; Li, D. G.; Chen, D. R.

2017-12-01

Two types of square wave anodization (type 1 and type 2) were employed in this work to form a passive film on Ti in a 0.5 M H2SO4 solution. The influences of the anodization potential and duration on the electronic properties and structures of the passive films were studied by Mott-Schottky plots, auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The results showed that the donor density, ND, of the passive film decreased and the flat band potential, EFB, shifted to the positive direction with the increase of the anodization duration and high anodization potential irrespective of whether type 1 or type 2 was used. Moreover, the passive film that formed on Ti using type 1 had a lower donor density and a more positive flat band potential than that on Ti using type 2 at one fixed anodization duration (only exchanging the anodization order of 1 V and the high potential). XPS analysis revealed that the outmost passive film was only composed of TiO2, the inner passive film was mainly composed of TiO2 with some amount of TiO and Ti2O3, and the TiO2 concentration in the outermost passive film increased with the increase of the anodization duration and the high potential in the case of using type 1 or type 2, implying an increased degree of crystallinity. The AES results showed that the O/Ti atomic ratio of the passive film obviously increased with the increasing anodization duration and high potential, demonstrating the increased homogeneous characteristic of the passive film; this was in agreement with the Mott-Schottky and XPS results.

Electrochemically synthesized nanocrystalline spinel thin film for high performance supercapacitor

NASA Astrophysics Data System (ADS)

Gupta, Vinay; Gupta, Shubhra; Miura, Norio

Spinels are not known for their supercapacitive nature. Here, we have explored electrochemically synthesized nanostructured NiCo 2O 4 spinel thin-film electrode for electrochemical supercapacitors. The nanostructured NiCo 2O 4 spinel thin film exhibited a high specific capacitance value of 580 F g -1 and an energy density of 32 Wh kg -1 at the power density of 4 kW kg -1, accompanying with good cyclic stability.

Effect of nitro substituent on electrochemical oxidation of phenols at boron-doped diamond anodes.

PubMed

Jiang, Yi; Zhu, Xiuping; Li, Hongna; Ni, Jinren

2010-02-01

In order to investigate nitro-substitutent's effect on degradation of phenols at boron-doped diamond (BDD) anodes, cyclic voltammetries of three nitrophenol isomers: 2-nitrophenol (2NP), 3-nitrophenol (3NP) and 4-nitrophenol (4NP) were studied, and their bulk electrolysis results were compared with phenol's (Ph) under alkaline condition. The voltammetric study showed nitrophenols could be attacked by hydroxyl radicals and nitro-group was released from the aromatic ring. Results of bulk electrolysis showed degradation of all phenols were fit to a pseudo first-order equation and followed in this order: 2NP>4NP>3NP>Ph. Molecular structures, especially carbon atom charge, significantly influenced the electrochemical oxidation of these isomers. Intermediates were analyzed during the electrolysis process, and were mainly catechol, resorcinol, hydroquinone, and carboxylic acids, such as acetic acid and oxalic acid. A simple degradation pathway was proposed. Moreover, a linear increasing relationship between degradation rates and Hammett constants of the studied phenols was observed, which demonstrated that electrochemical oxidation of these phenols was mainly initiated by electrophilic attack of hydroxyl radicals at BDD anodes. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Anodic stripping voltammetric determination of mercury using multi-walled carbon nanotubes film coated glassy carbon electrode.

PubMed

Yi, Hongchao

2003-10-01

An electrochemical method for the determination of trace levels of mercury based on a multi-walled carbon nanotubes (MWNT) film coated glassy carbon electrode (GCE) is described. In 0.1 mol L(-1) HCl solution containing 0.02 mol L(-1) KI, Hg(2+) was firstly preconcentrated at the MWNT film and then reduced at -0.60 V. During the anodic potential sweep, reduced mercury was oxidized, and then a sensitive and well-defined stripping peak at about -0.20 V appeared. Under identical conditions, a MWNT film coated GCE greatly enhances the stripping peak current of mercury in contrast to a bare GCE. Low concentrations of I(-) remarkably improve the determining sensitivity, since this increases the accumulation efficiency of Hg(2+) at the MWNT film coated GCE. The stripping peak current is proportional to the concentration of Hg(2+) over the range 8 x 10(-10)-5 x 10(-7) mol L(-1). The lowest detectable concentration of Hg(2+) is 2 x 10(-10) mol L(-1) at 5 min accumulation. The relative standard deviation (RSD) at 1 x 10(-8) mol L(-1) Hg(2+) was about 6% ( n=10). By using this proposed method, Hg(2+) in some water samples was determined, and the results were compared with those obtained by atomic absorption spectrometry (AAS). The two results are similar, suggesting that the MWNT-film coated GCE has great potential in practical analysis.

Effect of Adding SiO2-Al2O3 Sol into Anodizing Bath on Corrosion Resistance of Oxidation Film on Magnesium Alloy

NASA Astrophysics Data System (ADS)

Liu, Huicong; Zhu, Liqun; Li, Weiping

Due to the widely use in automobile and construction field, AZ91D magnesium alloy need to be protected more effectively for its high chemical activity. In this paper, three kinds of films were formed on magnesium alloy. The first kind of film, named as anodic oxidation film, was prepared by anodic oxidation in the alkaline solution. The processes for preparing the second kind of film, named as multiple film, involved coating sol-gel on the samples and heat-treating before anodic oxidation. The third kind of film was prepared by anodic oxidation in the alkaline oxidation solution containning 5% (vol) SiO2-Al2O3 sol, named as modified oxidation film. The corrosion resistance of the three different films was investigated. The results showed that the modified oxidation film had the highest corrosion resistance due to the largest thickness and most dense surface morphology. Sol was discussed to react during the film forming process, which leaded to the difference between modified oxidation film and anodic oxidation film.

Electrochemical writing on edible polysaccharide films for intelligent food packaging.

PubMed

Wu, Si; Wang, Wenqi; Yan, Kun; Ding, Fuyuan; Shi, Xiaowen; Deng, Hongbing; Du, Yumin

2018-04-15

Polysaccharide films used as intelligent food packaging possess the advantages of renewability, safety and biodegradability. Printing on the polysaccharidic food packaging is challenging due to the high demand for edible-ink and the need for a suitable printing technique. In this work, we propose an electrochemical method for writing on polysaccharide film. Unlike conventional printing, this electrochemical writing process relies on the pH responsive color change of anthocyanin embedded in the chitosan/agarose hydrogel. By biasing a negative potential to a stainless wire (used as a pen) contacting the surface of the chitosan/agarose/ATH hydrogel, the locally generated pH change induced the color change of ATH and wrote programmed information on the hydrogel. We demonstrate the writing can be temporary in the hydrogel but stable when the hydrogel is dried. We further demonstrate that the written film is applicable for the detection of the spoilage of crucian fish. The reported electrochemical writing process provides a novel method for printing information on polysaccharide film and great potential for intelligent food packaging. Copyright © 2018 Elsevier Ltd. All rights reserved.

Conductive Polymeric Binder for Lithium-Ion Battery Anode

NASA Astrophysics Data System (ADS)

Gao, Tianxiang

Tin (Sn) has a high-specific capacity (993 mAhg-1) as an anode material for Li-ion batteries. To overcome the poor cycling performance issue caused by its large volume expansion and pulverization during the charging and discharging process, many researchers put efforts into it. Most of the strategies are through nanostructured material design and introducing conductive polymer binders that serve as matrix of the active material in anode. This thesis aims for developing a novel method for preparing the anode to improve the capacity retention rate. This would require the anode to have high electrical conductivity, high ionic conductivity, and good mechanical properties, especially elasticity. Here the incorporation of a conducting polymer and a conductive hydrogel in Sn-based anodes using a one-step electrochemical deposition via a 3-electrode cell method is reported: the Sn particles and conductive component can be electrochemically synthesized and simultaneously deposited into a hybrid thin film onto the working electrode directly forming the anode. A well-defined three dimensional network structure consisting of Sn nanoparticles coated by conducting polymers is achieved. Such a conductive polymer-hydrogel network has multiple advantageous features: meshporous polymeric structure can offer the pathway for lithium ion transfer between the anode and electrolyte; the continuous electrically conductive polypyrrole network, with the electrostatic interaction with elastic, porous hydrogel, poly (2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylonitrile) (PAMPS) as both the crosslinker and doping anion for polypyrrole (PPy) can decrease the volume expansion by creating porous scaffold and softening the system itself. Furthermore, by increasing the amount of PAMPS and creating an interval can improve the cycling performance, resulting in improved capacity retention about 80% after 20 cycles, compared with only 54% of that of the control sample without PAMPS. The cycle

Investigation of the electrochemically active surface area and lithium diffusion in graphite anodes by a novel OsO4 staining method

NASA Astrophysics Data System (ADS)

Pfaffmann, Lukas; Birkenmaier, Claudia; Müller, Marcus; Bauer, Werner; Mitsch, Tim; Feinauer, Julian; Krämer, Yvonne; Scheiba, Frieder; Hintennach, Andreas; Schleid, Thomas; Schmidt, Volker; Ehrenberg, Helmut

2016-03-01

Negative electrodes of lithium-ion batteries generally consist of graphite-based active materials. In order to realize batteries with a high current density and therefore accelerated charging processes, the intercalation of lithium and the diffusion processes of these carbonaceous materials must be understood. In this paper, we visualized the electrochemical active surface area for three different anode materials using a novel OsO4 staining method in combination with scanning electron microscopy techniques. The diffusion behavior of these three anode materials is investigated by potentiostatic intermittent titration technique measurements. From those we determine the diffusion coefficient with and without consideration of the electrochemical active surface area.

Evaluation of double-layer density modulated Si thin films as Li-ion battery anodes

NASA Astrophysics Data System (ADS)

Taha Demirkan, Muhammed; Yurukcu, Mesut; Dursun, Burcu; Demir-Cakan, Rezan; Karabacak, Tansel

2017-10-01

Double-layer density modulated silicon thin films which contain alternating low and high density Si film layers were fabricated by magnetron sputtering. Two different samples consisting of alternating layers of high-density/low-density and low-density/high-density Si thin film layers were investigated as anode electrodes in Li-ion batteries. Si thin film in which the terminating layer at the top is low density Si layer-quoted as low-density/high-density film (LD/HD)- exhibits better performance than Si thin film that has high density layer at the top, -quoted as high-density/low-density (HD/LD). A highly stabilized cycling performance with the specific charge capacities of 2000 mAh g-1 at the 150th cycle at C/2 current density, and 1200 mAh g-1 at the 240th cycle at 10 C current density were observed for the LD/HD Si anode in the presence of fluoroethylene carbonate (FEC) electrolyte additive.

Application of silicon zig-zag wall arrays for anodes of Li-ion batteries

NASA Astrophysics Data System (ADS)

Li, G. V.; Rumyantsev, A. M.; Levitskii, V. S.; Beregulin, E. V.; Zhdanov, V. V.; Terukov, E. I.; Astrova, E. V.

2016-01-01

Cyclic tests of anodes based on zigzag wall arrays fabricated by the electrochemical etching and post-anodization treatment of silicon have been performed. Compared with anodes based on nanowires and planar thin films, these structures have several advantages. An ex situ analysis of the morphology and structural transformations in a material subjected to cyclic lithiation was conducted by electron microscopy and micro-Raman spectroscopy. The effect of geometrical parameters and a cycling mode on the degradation rate was studied. It is shown that a significant rise in the cycle life of the anode can be obtained by the restriction of the inserted amount of lithium. The anode, subjected to galvanostatic cycling at a rate C/2.8 at a limited charge capacity of 1000 mA · h g-1, demonstrates no degradation after 1200 cycles.

Fabrication and characterization of lithographically patterned and optically transparent anodic aluminum Oxide (AAO) nanostructure thin film.

PubMed

He, Yuan; Li, Xiang; Que, Long

2012-10-01

Optically transparent anodic aluminum oxide (AAO) nanostructure thin film has been successfully fabricated from lithographically patterned aluminum on indium tin oxide (ITO) glass substrates for the first time, indicating the feasibility to integrate the AAO nanostructures with microdevices or microfluidics for a variety of applications. Both one-step and two-step anodization processes using sulfuric acid and oxalic acid have been utilized for fabricating the AAO nanostructure thin film. The optical properties of the fabricated AAO nanostructure thin film have been evaluated and analyzed.

Growth and Etch Rate Study of Low Temperature Anodic Silicon Dioxide Thin Films

PubMed Central

Ashok, Akarapu; Pal, Prem

2014-01-01

Silicon dioxide (SiO2) thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs) and microelectromechanical systems (MEMS). Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics. PMID:24672287

Anodic behavior of uranium in AlCl3-1-ethyl-3-methyl-imidazolium chloride ionic liquid

NASA Astrophysics Data System (ADS)

Jiang, Yidong; Luo, Lizhu; Wang, Shaofei; Bin, Ren; Zhang, Guikai; Wang, Xiaolin

2018-01-01

The oxidation state of metals unambiguously affects its anodic behavior in ionic liquid. We systematically investigated the anodic behavior of uranium with different surface oxidation states by electrochemical measurements, spectroscopic methods and surface analysis techniques. In the anodic process, metal uranium can be oxidized to U3+. The corresponding products accumulated on the metal/ILs interface will form a viscous layer. The anodic behavior of uranium is also strongly dependent upon the surface oxide states including thickness and homogeneity of the oxide film. With an increase in the thickness of oxide film, it will be breached at potentials in excess of a critical value. A uniform oxide on uranium surface can be breached evenly, and then the underlying metal starts to dissolve forming a viscous layer which can facilitate uniformly stripping of oxide, thus giving an oxide-free surface. Otherwise, a nonuniform oxide can result in a severe pitted surface with residue oxygen.

Self-Organized Formation of Short TiO2 Nanotube Arrays By Complete Anodization of Ti Thin Films

NASA Astrophysics Data System (ADS)

Okada, Masahisa; Tajima, Kazuki; Yamada, Yasusei; Yoshimura, Kazuki

We investigate the self-organized growth of short TiO2 nanotubes by complete anodization of Ti thin films deposited on Si substrates in ethylene glycol electrolytes with small addition of NH4F. During the anodization process, real-time inspection of the current transient is performed to anodize the Ti films completely. X-ray photoelectron spectroscopy and scanning electron microscopy are employed to characterize the resulting samples. We find that the length of the formed TiO2 nanotubes is governed by the thickness of Ti thin films independently of the tube diameter. Short TiO2 nanotubes are also found to be stable up to 550 °C in air atmosphere even after crystallization to rutile.

XPS and biocompatibility studies of titania film on anodized NiTi shape memory alloy.

PubMed

Chu, C L; Wang, R M; Hu, T; Yin, L H; Pu, Y P; Lin, P H; Dong, Y S; Guo, C; Chung, C Y; Yeung, K W K; Chu, Paul K

2009-01-01

A dense titania film is fabricated in situ on NiTi shape memory alloy (SMA) by anodic oxidation in a Na(2)SO(4) electrolyte. The microstructure of the titania film and its influence on the biocompatibility of NiTi SMA are investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), hemolysis analysis, and platelet adhesion test. The results indicate that the titania film has a Ni-free zone near the surface and can effectively block the release of harmful Ni ions from the NiTi substrate in simulated body fluids. Moreover, the wettability, hemolysis resistance, and thromboresistance of the NiTi sample are improved by this anodic oxidation method.

High performance sandwich structured Si thin film anodes with LiPON coating

NASA Astrophysics Data System (ADS)

Luo, Xinyi; Lang, Jialiang; Lv, Shasha; Li, Zhengcao

2018-04-01

The sandwich structured silicon thin film anodes with lithium phosphorus oxynitride (LiPON) coating are synthesized via the radio frequency magnetron sputtering method, whereas the thicknesses of both layers are in the nanometer range, i.e. between 50 and 200 nm. In this sandwich structure, the separator simultaneously functions as a flexible substrate, while the LiPON layer is regarded as a protective layer. This sandwich structure combines the advantages of flexible substrate, which can help silicon release the compressive stress, and the LiPON coating, which can provide a stable artificial solidelectrolyte interphase (SEI) film on the electrode. As a result, the silicon anodes are protected well, and the cells exhibit high reversible capacity, excellent cycling stability and good rate capability. All the results demonstrate that this sandwich structure can be a promising option for high performance Si thin film lithium ion batteries.

High performance sandwich structured Si thin film anodes with LiPON coating

NASA Astrophysics Data System (ADS)

Luo, Xinyi; Lang, Jialiang; Lv, Shasha; Li, Zhengcao

2018-06-01

The sandwich structured silicon thin film anodes with lithium phosphorus oxynitride (LiPON) coating are synthesized via the radio frequency magnetron sputtering method, whereas the thicknesses of both layers are in the nanometer range, i.e. between 50 and 200 nm. In this sandwich structure, the separator simultaneously functions as a flexible substrate, while the LiPON layer is regarded as a protective layer. This sandwich structure combines the advantages of flexible substrate, which can help silicon release the compressive stress, and the LiPON coating, which can provide a stable artificial solid-electrolyte interphase (SEI) film on the electrode. As a result, the silicon anodes are protected well, and the cells exhibit high reversible capacity, excellent cycling stability and good rate capability. All the results demonstrate that this sandwich structure can be a promising option for high performance Si thin film lithium ion batteries.

Degradation Mechanisms of Electrochemically Cycled Graphite Anodes in Lithium-ion Cells

NASA Astrophysics Data System (ADS)

Bhattacharya, Sandeep

This research is aimed at developing advanced characterization methods for studying the surface and subsurface damage in Li-ion battery anodes made of polycrystalline graphite and identifying the degradation mechanisms that cause loss of electrochemical capacity. Understanding microstructural aspects of the graphite electrode degradation mechanisms during charging and discharging of Li-ion batteries is of key importance in order to design durable anodes with high capacity. An in-situ system was constructed using an electrochemical cell with an observation window, a large depth-of-field digital microscope and a micro-Raman spectrometer. It was revealed that electrode damage by removal of the surface graphite fragments of 5-10 mum size is the most intense during the first cycle that led to a drastic capacity drop. Once a solid electrolyte interphase (SEI) layer covered the electrode surface, the rate of graphite particle loss decreased. Yet, a gradual loss of capacity continued by the formation of interlayer cracks adjacent to SEI/graphite interfaces. Deposition of co-intercalation compounds, LiC6, Li2CO3 and Li2O, near the crack tips caused partial closure of propagating graphite cracks during cycling and reduced the crack growth rate. Bridging of crack faces by delaminated graphite layers also retarded crack propagation. The microstructure of the SEI layer, formed by electrochemical reduction of the ethylene carbonate based electrolyte, consisted of ˜5-20 nm sized crystalline domains (containing Li2CO3, Li2O 2 and nano-sized graphite fragments) dispersed in an amorphous matrix. During the SEI formation, two regimes of Li-ion diffusion were identified at the electrode/electrolyte interface depending on the applied voltage scan rate (dV/dt). A low Li-ion diffusion coefficient ( DLi+) at dV/dt < 0.05 mVs-1 produced a tubular SEI that uniformly covered the graphite surface and prevented damage at 25°C. At 60°C, a high D Li+ formed a Li2CO3-enriched SEI and ensued a

Electrochemical cell structure including an ionomeric barrier

DOEpatents

Lambert, Timothy N.; Hibbs, Michael

2017-06-20

An apparatus includes an electrochemical half-cell comprising: an electrolyte, an anode; and an ionomeric barrier positioned between the electrolyte and the anode. The anode may comprise a multi-electron vanadium phosphorous alloy, such as VP.sub.x, wherein x is 1-5. The electrochemical half-cell is configured to oxidize the vanadium and phosphorous alloy to release electrons. A method of mitigating corrosion in an electrochemical cell includes disposing an ionomeric barrier in a path of electrolyte or ion flow to an anode and mitigating anion accumulation on the surface of the anode.

Stimulated emission from aluminium anode oxide films doped with rhodamine 6G

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

Ibrayev, N Kh; Zeinidenov, A K; Aimukhanov, A K

The spectral and luminescent properties of the rhodamine 6G dye in a porous matrix of aluminium anode oxide are studied. The films with a highly-ordered porous structure are produced using the method of two-stage anodic oxidation. By means of raster electron microscopy it is found that the diameter of the pores amounts to nearly 50 nm and the separation between the adjacent channels is almost 105 nm. The thickness of the films is equal to 55 μm, and the specific surface area measured using the method of nitrogen capillary condensation is 15.3 m{sup 2} g{sup -1}. Fluorescence and absorption spectramore » of rhodamine 6G molecules injected into the pores of the aluminium anode oxide are measured. It is found that under the excitation of samples with the surface dye concentration 0.3 × 10{sup 14} molecules m{sup -2} by the second harmonic of the Nd : YAG laser in the longitudinal scheme with the pumping intensity 0.4 MW cm{sup -2}, a narrow band of stimulated emission with the intensity maximum at the wavelength 572 nm appears against the background of the laser-induced fluorescence spectrum. A further increase in the pumping radiation intensity leads to the narrowing of the stimulated emission band and an increase in its intensity. The obtained results demonstrate the potential possibility of using the porous films of aluminium anode oxide, doped with laser dyes, in developing active elements for quantum electronics. (laser applications and other topics in quantum electronics)« less

Transpassive Dissolution of Copper and Rapid Formation of Brilliant Colored Copper Oxide Films

NASA Astrophysics Data System (ADS)

Fredj, Narjes; Burleigh, T. David; New Mexico Tech Team

2014-03-01

This investigation describes an electrochemical technique for growing adhesive copper oxide films on copper with attractive colors ranging from gold-brown to pearl with intermediate colors from red violet to gold green. The technique consists of anodically dissolving copper at transpassive potentials in hot sodium hydroxide, and then depositing brilliant color films of Cu2O onto the surface of copper after the anodic potential has been turned off. The color of the copper oxide film depends on the temperature, the anodic potential, the time t1 of polarization, and the time t2, which is the time of immersion after potential has been turned off. The brilliant colored films were characterized using glancing angle x-ray diffraction, and the film was found to be primarily Cu2O. Cyclic voltammetry, chronopotentiometry, scanning electron microscopy, and x-ray photoelectron spectroscopy were also used to characterize these films.

Tricolor microcavity OLEDs based on P-nc-Si:H films as the complex anodes

NASA Astrophysics Data System (ADS)

Yang, Li; Xingyuan, Liu; Chunya, Wu; Zhiguo, Meng; Yi, Wang; Shaozhen, Xiong

2009-06-01

A P+-nc-Si:H film (boron-doped nc-Si:H thin film) was used as a complex anode of an OLED. As an ideal candidate for the composite anode, the P+-nc-Si:H thin film has a good conductivity with a high work function (~ 5.7 eV) and outstanding optical properties of high reflectivity, transmission, and a very low absorption. As a result, the combination of the relatively high reflectivity of a P+-nc-Si:H film/ITO complex anode with the very high reflectivity of an Al cathode could form a micro-cavity structure with a certain Q to improve the efficiency of the OLED fabricated on it. An RGB pixel generated by microcavity OLEDs is beneficial for both the reduction of the light loss and the improvement of the color purity and the efficiency. The small molecule Alq would be useful for the emitting light layer (EML) of the MOLED, and the P+-nc-Si film would be used as a complex anode of the MOLED, whose configuration can be constructed as Glass/LTO/P+-nc-Si:H/ITO/MoO3/NPB/Alq/LiF/Al. By adjusting the thickness of the organic layer NPB/Alq, the optical length of the microcavity and the REB colors of the device can be obtained. The peak wavelengths of an OLED are located at 486, 550, and 608 nm, respectively. The CIE coordinates are (0.21, 0.45), (0.33, 0.63), and (0.54, 0.54), and the full widths at half maximum (FWHM) are 35, 32, and 39 nm for red, green, and blue, respectively.

Enhancing cycling durability of Li-ion batteries with hierarchical structured silicon-graphene hybrid anodes.

PubMed

Loveridge, Melanie J; Lain, Michael J; Huang, Qianye; Wan, Chaoying; Roberts, Alexander J; Pappas, George S; Bhagat, Rohit

2016-11-09

Hybrid anode materials consisting of micro-sized silicon (Si) particles interconnected with few-layer graphene (FLG) nanoplatelets and sodium-neutralized poly(acrylic acid) as a binder were evaluated for Li-ion batteries. The hybrid film has demonstrated a reversible discharge capacity of ∼1800 mA h g -1 with a capacity retention of 97% after 200 cycles. The superior electrochemical properties of the hybrid anodes are attributed to a durable, hierarchical conductive network formed between Si particles and the multi-scale carbon additives, with enhanced cohesion by the functional polymer binder. Furthermore, improved solid electrolyte interphase (SEI) stability is achieved from the electrolyte additives, due to the formation of a kinetically stable film on the surface of the Si.

Electrochemical treatment of cork boiling wastewater with a boron-doped diamond anode.

PubMed

Fernandes, Annabel; Santos, Diana; Pacheco, Maria José; Ciríaco, Lurdes; Simões, Rogério; Gomes, Arlindo C; Lopes, Ana

2015-01-01

Anodic oxidation at a boron-doped diamond anode of cork boiling wastewater was successfully used for mineralization and biodegradability enhancement required for effluent discharge or subsequent biological treatment, respectively. The influence of the applied current density (30-70 mA/cm2) and the background electrolyte concentration (0-1.5 g/L Na2SO4) on the performance of the electrochemical oxidation was investigated. The supporting electrolyte was required to achieve conductivities that enabled anodic oxidation at the highest current intensities applied. The results indicated that pollutant removal increased with the applied current density, and after 8 h, reductions greater than 90% were achieved for COD, dissolved organic carbon, total phenols and colour. The biodegradability enhancement was from 0.13 to 0.59 and from 0.23 to 0.72 for the BOD/COD ratios with BOD of 5 and 20 days' incubation period, respectively. The tests without added electrolyte were performed at lower applied electrical charges (15 mA/cm2 or 30 V) with good organic load removal (up to 80%). For an applied current density of 30 mA/cm2, there was a minimum of electric conductivity of 1.9 mS/cm (corresponding to 0.75 g/L of Na2SO4), which minimized the specific energy consumption.

Model anodes and anode models for understanding the mechanism of hydrogen oxidation in solid oxide fuel cells.

PubMed

Bessler, Wolfgang G; Vogler, Marcel; Störmer, Heike; Gerthsen, Dagmar; Utz, Annika; Weber, André; Ivers-Tiffée, Ellen

2010-11-14

This article presents a literature review and new results on experimental and theoretical investigations of the electrochemistry of solid oxide fuel cell (SOFC) model anodes, focusing on the nickel/yttria-stabilized zirconia (Ni/YSZ) materials system with operation under H(2)/H(2)O atmospheres. Micropatterned model anodes were used for electrochemical characterization under well-defined operating conditions. Structural and chemical integrity was confirmed by ex situ pre-test and post-test microstructural and chemical analysis. Elementary kinetic models of reaction and transport processes were used to assess reaction pathways and rate-determining steps. The comparison of experimental and simulated electrochemical behaviors of pattern anodes shows quantitative agreement over a wide range of operating conditions (p(H(2)) = 8×10(2) - 9×10(4) Pa, p(H(2)O) = 2×10(1) - 6×10(4) Pa, T = 400-800 °C). Previously published experimental data on model anodes show a strong scatter in electrochemical performance. Furthermore, model anodes exhibit a pronounced dynamics on multiple time scales which is not reproduced in state-of-the-art models and which is also not observed in technical cermet anodes. Potential origin of these effects as well as consequences for further steps in model anode and anode model studies are discussed.

Label-free electrochemical genosensor based on mesoporous silica thin film.

PubMed

Saadaoui, Maroua; Fernández, Iñigo; Luna, Gema; Díez, Paula; Campuzano, Susana; Raouafi, Noureddine; Sánchez, Alfredo; Pingarrón, José M; Villalonga, Reynaldo

2016-10-01

A novel label-free electrochemical strategy for nucleic acid detection was developed by using gold electrodes coated with mesoporous silica thin films as sensing interface. The biosensing approach relies on the covalent attachment of a capture DNA probe on the surface of the silica nanopores and further hybridization with its complementary target oligonucleotide sequence, causing a diffusion hindering of an Fe(CN)6 (3-/4-) electrochemical probe through the nanochannels of the mesoporous film. This DNA-mesoporous silica thin film-modified electrodes allowed sensitive (91.7 A/M) and rapid (45 min) detection of low nanomolar levels of synthetic target DNA (25 fmol) and were successfully employed to quantify the endogenous content of Escherichia coli 16S ribosomal RNA (rRNA) directly in raw bacterial lysate samples without isolation or purification steps. Moreover, the 1-month stability demonstrated by these biosensing devices enables their advanced preparation and storage, as desired for practical real-life applications. Graphical abstract Mesoporous silica thin films as scaffolds for the development of novel label-free electrochemical genosensors to perform selective, sensitive and rapid detection of target oligonucleotide sequences. Application towards E. coli determination.

Electrochemical oxidation of tetracycline antibiotics using a Ti/IrO2 anode for wastewater treatment of animal husbandry.

PubMed

Miyata, M; Ihara, I; Yoshid, G; Toyod, K; Umetsu, K

2011-01-01

In animal husbandry, antibiotics are widely used to treat and prevent diseases or to promote growth. The use of antibiotics for domestic animals enables to promote safety of livestock products and enhance productivity. Tetracycline antibiotics (TCs) are one of the primarily used groups of antibiotics for cattle and swine. However, the unintentional spreading of antibiotics from animal waste to the environment may leave out drug residues, promoting resistant strains of bacteria, and will adversely affect the ecosystem and human health. To prevent the spread of veterinary antibiotics in the environment, it is required to treat residual antibiotics in livestock wastewater. In this study, we investigated the electrochemical oxidation of TCs to treat livestock wastewater. The concentrations of TCs in aqueous solutions were reduced from 100 mg/L to less than 0.6 mg/L by 6 h of electrochemical treatment using a Ti/IrO2 anode with Na2SO4 electrolyte. The concentration of oxytetracycline (OTC) in livestock wastewater was also reduced from 100 mg/L to less than 0.7 mg/L by the same treatment. Thus, the electrochemical oxidation using a Ti/IrO2 anode with Na2SO4 electrolyte was found to be effective for degradation of TCs. The results suggest that the electrochemical oxidation method is a promising treatment for TCs in livestock wastewater.

Enhanced electrochemical performance and carbon anti-coking ability of solid oxide fuel cells with silver modified nickel-yttrium stabilized zirconia anode by electroless plating

NASA Astrophysics Data System (ADS)

Wu, Xiaoyan; Tian, Yu; Zhang, Jun; Zuo, Wei; Kong, Xiaowei; Wang, Jinghui; Sun, Kening; Zhou, Xiaoliang

2016-01-01

In this paper, silver (Ag) particles are introduced into the conventional Ni/YSZ anode by utilizing electroless plating method to improve its carbon anti-coking ability in hydrocarbons. The experimental results show that electrochemical performances of the decorated cells in H2, CH4 and C2H6 are all increased as compared to the cell with unmodified Ni/YSZ anode, which are verified by impedance spectrums as well. The durability experiment is carried out for as long as 24 h at the current density of 0.33 A/cm2 where the modified anode is subjected to dry C2H6 indicating the anti-coking ability of the anode is greatly improved. Scanning electron microscope shows that the slight decreasing in the cell terminal voltage can be attributed to the minimized carbon deposition which maybe resulted from the aggregation of silver particles at high temperature. Energy-dispersive X-ray spectroscopy line scanning results after long-term stability operation of the anode suggest that the carbon deposition can be depressed effectively both inside the anode and on the surface of the anode. Therefore, the results show that silver is a promising candidate material for modifying the Ni/YSZ anode with regard to improving electrochemical performance and suppressing the carbon deposition when taking the hydrocarbons as fuels.

Microfluidic devices with thick-film electrochemical detection

DOEpatents

Wang, Joseph; Tian, Baomin; Sahlin, Eskil

2005-04-12

An apparatus for conducting a microfluidic process and analysis, including at least one elongated microfluidic channel, fluidic transport means for transport of fluids through the microfluidic channel, and at least one thick-film electrode in fluidic connection with the outlet end of the microfluidic channel. The present invention includes an integrated on-chip combination reaction, separation and thick-film electrochemical detection microsystem, for use in detection of a wide range of analytes, and methods for the use thereof.

Chemometric study on the electrochemical incineration of diethylenetriaminepentaacetic acid using boron-doped diamond anode.

PubMed

Xian, Jiahui; Liu, Min; Chen, Wei; Zhang, Chunyong; Fu, Degang

2018-05-01

The electrochemical incineration of diethylenetriaminepentaacetic acid (DTPA) with boron-doped diamond (BDD) anode had been initially performed under galvanostatic conditions. The main and interaction effects of four operating parameters (flow rate, applied current density, sulfate concentration and initial DTPA concentration) on mineralization performance were investigated. Under similar experimental conditions, Doehlert matrix (DM) and central composite rotatable design (CCRD) were used as statistical multivariate methods in the optimization of the anodic oxidation processes. A comparison between DM model and CCRD model revealed that the former was more accurate, possibly due to its higher operating level numbers employed (7 levels for two variables). Despite this, these two models resulted in quite similar optimum operating conditions. The maximum TOC removal percentages at 180 min were 76.2% and 73.8% for case of DM and CCRD, respectively. In addition, with the aid of quantum chemistry calculation and LC/MS analysis, a plausible degradation sequence of DTPA on BDD anode was also proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electrochemical testing of industrially produced PEO-based polymer electrolytes

NASA Astrophysics Data System (ADS)

Appetecchi, G. B.; Alessandrini, F.; Duan, R. G.; Arzu, A.; Passerini, S.

The present report describes the results of the electrochemical tests performed on polyethyleneoxide-based polymer electrolyte thin films industrially manufactured by blown-extrusion. The polymer electrolyte composition was PEO 20 LiCF 3SO 3: 16.7% γLiAlO 2. The polymer electrolyte film was tested to evaluate the ionic conductivity as well as the interfacial properties with lithium metal anodes. The work was developed within the advanced lithium polymer electrolyte (ALPE) project, an Italian project devoted to the realization of lithium polymer batteries for electric vehicle applications, in collaboration with Union Carbide.

Electrochemical reduction of UO2 in LiCl-Li2O molten salt using porous and nonporous anode shrouds

NASA Astrophysics Data System (ADS)

Choi, Eun-Young; Won, Chan Yeon; Cha, Ju-Sun; Park, Wooshin; Im, Hun Suk; Hong, Sun-Seok; Hur, Jin-Mok

2014-01-01

Electrochemical reductions of uranium oxide in a molten LiCl-Li2O electrolyte were carried out using porous and nonporous anode shrouds. The study focused on the effect of the type of anode shroud on the current density by running experiments with six anode shrouds. Dense ceramics, MgO, and MgO (3 wt%) stabilized ZrO2 (ZrO2-MgO) were used as nonporous shrouds. STS 20, 100, and 300 meshes and ZrO2-MgO coated STS 40 mesh were used as porous shrouds. The current densities (0.34-0.40 A cm-2) of the electrolysis runs using the nonporous anode shrouds were much lower than those (0.76-0.79 A cm-2) of the runs using the porous shrouds. The ZrO2-MgO shroud (600-700 MPa at 25 °C) showed better bending strength than that of MgO (170 MPa at 25 °C). The high current densities achieved in the electrolysis runs using the porous anode shrouds were attributed to the transport of O2- ions through the pores in meshes of the shroud wall. ZrO2-MgO coating on STS mesh was chemically unstable in a molten LiCl-Li2O electrolyte containing Li metal. The electrochemical reduction runs using STS 20, 100, and 300 meshes showed similar current densities in spite of their different opening sizes. The STS mesh shrouds which were immersed in a LiCl-Li2O electrolyte were stable without any damage or corrosion.

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.

Fabrication of luminescent SrWO{sub 4} thin films by a novel electrochemical method

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

Chen Lianping; Gao Yuanhong

2007-10-02

Highly crystallized SrWO{sub 4} thin films with single scheelite structure were prepared within 60 min by a cell electrochemical method. X-ray diffraction analysis shows that SrWO{sub 4} thin films have a tetragonal structure. Scanning electron microscopy examinations reveal that SrWO{sub 4} grains grow well in tetragonal tapers and grains like flowers or bunches, which can usually form by using the electrolysis electrochemical method, have disappeared under cell electrochemical conditions. X-ray photoelectron spectra and energy dispersive X-ray microanalysis examinations demonstrate that the composition of the film is consistent with its stoichiometry. These SrWO{sub 4} films show a single blue emission peakmore » (located at 460 nm) using an excitation wave of 230 nm. The speed of cell electrochemical method can be controlled by changing temperature. The optimum treatment temperature is about 50-60 deg. C.« less

Gelation Mechanisms and Characterization of Electrochemically Generated Protein Films at Metal Interfaces

NASA Astrophysics Data System (ADS)

Martin, Elizabeth J.

Although the electrochemical behavior of metals used in orthopedic implants has been studied extensively, the material interactions with proteins during corrosion processes remains poorly understood. Some studies suggest that metal-protein interactions accelerate corrosion, while others suggest that proteins protect the material from degradation. Corrosion of implant materials is a major concern due to the metal ion release that can sometimes cause adverse local tissue reactions and ultimately, failure of the implant. The initial purpose of this research was therefore to study the corrosion behavior of CoCrMo, an alloy commonly used in hip replacements, with a quartz crystal microbalance (QCM) in physiologically relevant media. The QCM enables in situ characterization of surface changes accompanying corrosion and is sensitive to viscoelastic effects at its surface. Results of QCM studies in proteinaceous media showed film deposition on the alloy surface under electrochemical conditions that otherwise produced mass loss if proteins were not present in the electrolyte. Additional studies on pure Co, Cr, and Mo demonstrated that the protein films also form on Mo surfaces after a release of molybdate ions, suggesting that these ions are essential for film formation. The electrochemically generated protein films are reminiscent of carbonaceous films that form on implant surfaces in vivo, therefore a second goal of the research was to delineate mechanisms that cause the films to form. In the second stage of this research, electrochemical QCM tests were conducted on models of the CoCrMo system consisting of Cr electrodes in proteinaceous or polymeric media containing dissolved molybdate ions. Studies indicated that films can be generated through electrochemical processes so long as both amine functional groups and molybdate ions are present in the electrolyte solution. These results suggest that the films form due to an ionic cross-linking reaction between the positively

Method for synthesizing thin film electrodes

DOEpatents

Boyle, Timothy J [Albuquerque, NM

2007-03-13

A method for making a thin-film electrode, either an anode or a cathode, by preparing a precursor solution using an alkoxide reactant, depositing multiple thin film layers with each layer approximately 500 1000 .ANG. in thickness, and heating the layers to above 600.degree. C. to achieve a material with electrochemical properties suitable for use in a thin film battery. The preparation of the anode precursor solution uses Sn(OCH.sub.2C(CH.sub.3).sub.3).sub.2 dissolved in a solvent in the presence of HO.sub.2CCH.sub.3 and the cathode precursor solution is formed by dissolving a mixture of (Li(OCH.sub.2C(CH.sub.3).sub.3)).sub.8 and Co(O.sub.2CCH.sub.3).H.sub.2O in at least one polar solvent.

A dynamic inert metal anode.

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

Hryn, J. N.

1998-11-09

A new concept for a stable anode for aluminum electrowinning is described. The anode consists of a cup-shaped metal alloy container filled with a molten salt that contains dissolved aluminum. The metal alloy can be any of a number of alloys, but it must contain aluminum as a secondary alloying metal. A possible alloy composition is copper with 5 to 15 weight percent aluminum. In the presence of oxygen, aluminum on the metal anode's exterior surface forms a continuous alumina film that is thick enough to protect the anode from chemical attack by cryolite during electrolysis and thin enough tomore » maintain electrical conductivity. However, the alumina film is soluble in cryolite, so it must be regenerated in situ. Film regeneration is achieved by the transport of aluminum metal from the anode's molten salt interior through the metal wall to the anode's exterior surface, where the transported aluminum oxidizes to alumina in the presence of evolving oxygen to maintain the protective alumina film. Periodic addition of aluminum metal to the anode's interior keeps the aluminum activity in the molten salt at the desired level. This concept for an inert anode is viable as long as the amount of aluminum produced at the cathode greatly exceeds the amount of aluminum required to maintain the anode's protective film.« less

Co-extrusion of electrolyte/anode functional layer/anode triple-layer ceramic hollow fibres for micro-tubular solid oxide fuel cells-electrochemical performance study

NASA Astrophysics Data System (ADS)

Li, Tao; Wu, Zhentao; Li, K.

2015-01-01

In this study, the effects of an anode functional layer (AFL) with controlled thickness on physical and electrochemical properties of a micro-tubular SOFC have been systematically studied. A series of electrolyte/AFL/anode triple-layer hollow fibres with controllable AFL thicknesses (16.9-52.7 μm) have been fabricated via a single-step phase-inversion assisted co-extrusion technique. Both robustness of the cell and gas-tightness of the electrolyte layer are considerably improved by introducing the AFL of this type. The fracture force of the sample with the thickest AFL (9.67 N) almost doubles when compared to the electrolyte/anode dual-layer counterpart (5.24 N). Gas-tightness of the electrolyte layer is also considerably increased as AFL contributes to better-matched sintering behaviours between different components. Moreover, the formation of an AFL simultaneously with electrolyte and anode significantly improves the cell performances. The sample with the thinnest AFL (approximately 16.9 μm, 6% of the total anode thickness) leads to a 30% (from 0.89 to 1.21 W cm-2) increase in maximum power density, due to increased triple-phase boundaries (TPB). However, further increase in TPB from a thicker AFL is less effective for improving the cell performance, due to the substantially increased fuel diffusion resistance and subsequently higher concentration polarization. This indicates that the control over the AFL thickness is critically important in avoiding offsetting the benefits of extended TPB and consequently decreased cell performances.

Metallic anodes for next generation secondary batteries.

PubMed

Kim, Hansu; Jeong, Goojin; Kim, Young-Ugk; Kim, Jae-Hun; Park, Cheol-Min; Sohn, Hun-Joon

2013-12-07

Li-air(O2) and Li-S batteries have gained much attention recently and most relevant research has aimed to improve the electrochemical performance of air(O2) or sulfur cathode materials. However, many technical problems associated with the Li metal anode have yet to be overcome. This review mainly focuses on the electrochemical behaviors and technical issues related to metallic Li anode materials as well as other metallic anode materials such as alkali (Na) and alkaline earth (Mg) metals, including Zn and Al when these metal anodes were employed for various types of secondary batteries.

The Effects of Film Thickness and Evaporation Rate on Si-Cu Thin Films for Lithium Ion Batteries.

PubMed

Polat, B Deniz; Keles, Ozgul

2015-12-01

The reversible cyclability of Si based composite anodes is greatly improved by optimizing the atomic ratio of Si/Cu, the thickness and the evaporation rates of films fabricated by electron beam deposition method. The galvanostatic test results show that 500 nm thick flim, having 10%at. Cu-90%at. Si, deposited with a moderate evaporation rate (10 and 0.9 Å/s for Si and Cu respectively) delivers 2642.37 mAh g(-1) as the first discharge capacity with 76% Coulombic efficiency. 99% of its initial capacity is retained after 20 cycles. The electron conductive pathway and high mechanical tolerance induced by Cu atoms, the low electrical resistivity of the film due to Cu3Si particles, and the homogeneously distributed nano-sized/amorphous particles in the composite thin film could explain this outstanding electrochemical performance of the anode.

Fabrication of porous anodic alumina using normal anodization and pulse anodization

NASA Astrophysics Data System (ADS)

Chin, I. K.; Yam, F. K.; Hassan, Z.

2015-05-01

This article reports on the fabrication of porous anodic alumina (PAA) by two-step anodizing the low purity commercial aluminum sheets at room temperature. Different variations of the second-step anodization were conducted: normal anodization (NA) with direct current potential difference; pulse anodization (PA) alternate between potential differences of 10 V and 0 V; hybrid pulse anodization (HPA) alternate between potential differences of 10 V and -2 V. The method influenced the film homogeneity of the PAA and the most homogeneous structure was obtained via PA. The morphological properties are further elucidated using measured current-transient profiles. The absent of current rise profile in PA indicates the anodization temperature and dissolution of the PAA structure were greatly reduced by alternating potential differences.

Preparation of titanium dioxide films on etched aluminum foil by vacuum infiltration and anodizing

NASA Astrophysics Data System (ADS)

Xiang, Lian; Park, Sang-Shik

2016-12-01

Al2O3-TiO2 (Al-Ti) composite oxide films are a promising dielectric material for future use in capacitors. In this study, TiO2 films were prepared on etched Al foils by vacuum infiltration. TiO2 films prepared using a sol-gel process were annealed at various temperatures (450, 500, and 550 °C) for different time durations (10, 30, and 60 min) for 4 cycles, and then anodized at 100 V. The specimens were characterized using X-ray diffraction, field emission scanning electron microscopy, and field emission transmission electron microscopy. The results show that the tunnels of the specimens feature a multi-layer structure consisting of an Al2O3 outer layer, an Al-Ti composite oxide middle layer, and an aluminum hydrate inner layer. The electrical properties of the specimens, such as the withstanding voltage and specific capacitance, were also measured. Compared to specimens without TiO2 coating, the specific capacitances of the TiO2-coated specimens are increased. The specific capacitance of the anode Al foil with TiO2 coating increased by 42% compared to that of a specimen without TiO2 coating when annealed at 550 °C for 10 min. These composite oxide films could enhance the specific capacitance of anode Al foils used in dielectric materials.

Reaction mechanism of electrochemical-vapor deposition of yttria-stabilized zirconia film

NASA Astrophysics Data System (ADS)

Sasaki, Hirokazu; Yakawa, Chiori; Otoshi, Shoji; Suzuki, Minoru; Ippommatsu, Masamichi

1993-10-01

The reaction mechanism for electrochemical-vapor deposition of yttria-stabilized zirconia was studied. Yttria-stabilized zirconia films were deposited on porous La(Sr)MnOx using the electrochemical-vapor-deposition process. The distribution of yttria concentration through the film was investigated by means of secondary-ion-mass spectroscopy and x-ray microanalysis and found to be nearly constant. The deposition rate was approximately proportional to the minus two-thirds power of the film thickness, the one-third power of the partial pressure of ZrCl4/YCl3 mixed gas, and the two-thirds power of the product of the reaction temperature and the electronic conductivity of yttria-stabilized zirconia film. These experimental results were explained by a model for electron transport through the YSZ film and reaction between the surface oxygen and the metal chloride on the chloride side of the film, both of which affect the deposition rate. If the film thickness is very small, the deposition rate is thought to be controlled by the surface reaction step. On the other hand, if large, the electron transport step is rate controlling.

Electrochemically deposited cobalt/platinum (Co/Pt) film into porous silicon: Structural investigation and magnetic properties

NASA Astrophysics Data System (ADS)

Harraz, F. A.; Salem, A. M.; Mohamed, B. A.; Kandil, A.; Ibrahim, I. A.

2013-01-01

A nanostructured CoPt magnetic film was deposited from a single electrolyte into porous silicon layer by an electrochemical technique, followed by annealing at 600 °C in Ar atmosphere during which the CoPt alloy was converted to L10 ordered phase. Porous silicon with pore diameter between 5 and 100 nm was firstly fabricated by galvanostatic anodization of n-type silicon wafer in the presence of CrO3 as oxidizing agent and ethanol or sodium lauryl sulfate as surfactants. The role of the surfactant on the produced pore size and morphology was investigated by means of UV-vis spectra. As-formed porous silicon was consequently used as a template for the electrodeposition of magnetic CoPt film. The phase formation, microstructure and the magnetic properties were fully analyzed by XRD, FE-SEM, EDS and VSM measurements. It was found that, upon annealing the coercivity was significantly increased due to the transformation to the L10 ordered structure. The saturation magnetization and remanence ratio were also found to increase, indicating no loss of Co content or oxidation reaction after the annealing. Results of synthesis and characterization of CoPt/porous silicon nanocomposite are addressed and thoroughly discussed.

Morphology in electrochemically grown conducting polymer films

DOEpatents

Rubinstein, Israel; Gottesfeld, Shimshon; Sabatani, Eyal

1992-01-01

A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventioonally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol.

Morphology in electrochemically grown conducting polymer films

DOEpatents

Rubinstein, I.; Gottesfeld, S.; Sabatani, E.

1992-04-28

A conducting polymer film with an improved space filling is formed on a metal electrode surface. A self-assembling monolayer is formed directly on the metal surface where the monolayer has a first functional group that binds to the metal surface and a second chemical group that forms a chemical bonding site for molecules forming the conducting polymer. The conducting polymer is then conventionally deposited by electrochemical deposition. In one example, a conducting film of polyaniline is formed on a gold electrode surface with an intermediate monolayer of p-aminothiophenol. 2 figs.

Red Phosphorus-Embedded Cross-Link-Structural Carbon Films as Flexible Anodes for Highly Reversible Li-Ion Storage

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

Ruan, Jiafeng; Yuan, Tao; Pang, Yuepeng

Red phosphorus (P) is considered to be one of the most attractive anodic materials for lithium-ion batteries (LIBs) due to its high theoretical capacity of 2596 mAh g–1. However, intrinsic characteristics such as the poor electronic conductivity and large volume expansion at lithiation impede the development of red P. Here, we design a new strategy to embed red P particles into a cross-link-structural carbon film (P–C film), in order to improve the electronic conductivity and accommodate the volume expansion. The red P/carbon film is synthesized via vapor phase polymerization (VPP) followed by the pyrolysis process, working as a flexible binder-freemore » anode for LIBs. High cycle stability and good rate capability are achieved by the P–C film anode. With 21% P content in the film, it displays a capacity of 903 mAh g–1 after 640 cycles at a current density of 100 mA g–1 and a capacity of 460 mAh g–1 after 1000 cycles at 2.0 A g–1. Additionally, the Coulombic efficiency reaches almost 100% for each cycle. The superior properties of the P–C films together with their facile fabrication make this material attractive for further flexible and high energy density LIB applications.« less

Effect of the layer of anodized 7075-T6 aluminium corrosion properties

NASA Astrophysics Data System (ADS)

Montoya Z, R. D.; L, E. Vera; Pineda T, Y.; Cedeño, M. L.

2017-01-01

Aluminium alloys are widely used in various sectors of industry. The 7075-T6 alloy corresponding to an Al-Zn T6, is mostly used as structural component in the aviation industry, due to the good relationship between weight and mechanical properties. However, the negative point of this alloys is the resistance to corrosion, which is why they need to be coated with an anodic film. Different surface treatments, such as anodizing, are used to improve corrosion resistance. Anodizing is an electrolytic process by which a protective layer on aluminium known as “alumina” is formed, this is formed by the passage of an electric current in an acidic electrolyte. This investigation presents a study of the effect of the thickness of layers of alumina deposited by anodized method, in the corrosion resistance of 7075-T6 aluminium. This study was performed by using in a solution of tartaric acid - sulfuric acid and an inorganic salt. To evaluate the influence alumina layer thickness on the corrosion properties some tests were carried out by using the electrochemical spectroscopy impedances (EIS) technique and Tafel polarization curves. It was found that the grown of the thickness of film favourably influences in the corrosion resistance.

Synthesis of Coral-Like Tantalum Oxide Films via Anodization in Mixed Organic-Inorganic Electrolytes

PubMed Central

Yu, Hongbin; Zhu, Suiyi; Yang, Xia; Wang, Xinhong; Sun, Hongwei; Huo, Mingxin

2013-01-01

We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two–electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%. PMID:23799106

[Research of the surface oxide film on anodizing Ni-Cr porcelain alloy].

PubMed

Zhu, Song; Sun, Hong-Chen; Zhang, Jing-Wei; Li, Zong-Hui

2006-08-01

To study the shape, thickness and oxide percentage of major metal element of oxide film on Ni-Cr porcelain alloy after anodizing pretreatment. 10 samples were made and divided into 2 groups at random. Then after surface pretreatment, the oxide films of two samples of each group were analyzed using electronic scanning microscope. The rest 3 samples were measured by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Lightly selective solution appeared because the different component parts of the alloy have dissimilar electrode, whose dissolve velocity were quite unlike. The sample's metal surface expanded, so the mechanical interlocking of porcelain and metal increased bond strength. The thickness of oxide film was 1.72 times of the control samples. The oxide percentage of major metal elements such as Cr, Ni and Mo were higher, especially Cr. It initially involved the formation of a thin oxide bound to the alloy and second, the ability of the formed oxide to saturate the porcelain, completing the chemical bond of porcelain to metal. The method of anodizing Ni-Cr porcelain alloy can easily control the forming of oxide film which was thin and its surface pattern was uniform. It is repeated and a good method of surface pretreatment before firing cycle.

Penetrating the oxide barrier in situ and separating freestanding porous anodic alumina films in one step.

PubMed

Tian, Mingliang; Xu, Shengyong; Wang, Jinguo; Kumar, Nitesh; Wertz, Eric; Li, Qi; Campbell, Paul M; Chan, Moses H W; Mallouk, Thomas E

2005-04-01

A simple method for penetrating the barrier layer of an anodic aluminum oxide (AAO) film and for detaching the AAO film from residual Al foil was developed by reversing the bias voltage in situ after the anodization process is completed. With this technique, we have been able to obtain large pieces of free-standing AAO membranes with regular pore sizes of sub-10 nm. By combining Ar ion milling and wetting enhancement processes, Au nanowires were grown in the sub-10 nm pores of the AAO films. Further scaling down of the pore size and extension to the deposition of nanowires and nanotubes of materials other than Au should be possible by further optimizing this procedure.

Electrochemically controlled drug-mimicking protein release from iron-alginate thin-films associated with an electrode.

PubMed

Jin, Zhiyuan; Güven, Güray; Bocharova, Vera; Halámek, Jan; Tokarev, Ihor; Minko, Sergiy; Melman, Artem; Mandler, Daniel; Katz, Evgeny

2012-01-01

Novel biocompatible hybrid-material composed of iron-ion-cross-linked alginate with embedded protein molecules has been designed for the signal-triggered drug release. Electrochemically controlled oxidation of Fe(2+) ions in the presence of soluble natural alginate polymer and drug-mimicking protein (bovine serum albumin, BSA) results in the formation of an alginate-based thin-film cross-linked by Fe(3+) ions at the electrode interface with the entrapped protein. The electrochemically generated composite thin-film was characterized by electrochemistry and atomic force microscopy (AFM). Preliminary experiments demonstrated that the electrochemically controlled deposition of the protein-containing thin-film can be performed at microscale using scanning electrochemical microscopy (SECM) as the deposition tool producing polymer-patterned spots potentially containing various entrapped drugs. Application of reductive potentials on the modified electrode produced Fe(2+) cations which do not keep complexation with alginate, thus resulting in the electrochemically triggered thin-film dissolution and the protein release. Different experimental parameters, such as the film-deposition time, concentrations of compounds and applied potentials, were varied in order to demonstrate that the electrodepositon and electrodissolution of the alginate composite film can be tuned to the optimum performance. A statistical modeling technique was applied to find optimal conditions for the formation of the composite thin-film for the maximal encapsulation and release of the drug-mimicking protein at the lowest possible potential. © 2011 American Chemical Society

Studies of an extractor geometry magnetically insulated ion diode with an exploding metal film anode plasma

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

Rondeau, G.D.

1989-01-01

Magnetically insulated diodes (MIDs) are of interest as ion sources for inertial confinement fusion. The authors examined several issues that are of concern with MIDs, including ion turn-on delay and anode plasma production, and diode impedance history and particle current scaling with the applied magnetic field and gas spacing. The LION pulsed power generator (1.5 MV, 4 {Omega}, 40 ns pulse length) was used to power an extractor geometry magnetically insulated (radical magnetic field) ion beam diode. The diode was studied with three anode configurations. In the first, with epoxy-filled-groove (epoxy) anodes, scaling of the ion and electron currents withmore » the gap and the magnetic field was examined. He found that the observed ion current is consistent with a diode model that has been successful with barrel geometry MIDs. The electron leakage current scaled proportionally to 1/Bd{sup 2}, where d is the anode-cathode gap spacing and B is the magnetic field strength. Studies of ion beam propagation in vacuum showed that space charge non-neutrality near the magnetic field coils caused the beam to expand initially. Later in the ion pulse (20 to 30 ns), the beam expansion became much less severe. The second anode configuration utilized an electron collector protruding above an epoxy anode surface. With the collector, he observed less bremsstrahlung across the active anode region. The last anode configuration studied was the exploding metal film active anode plasma source (EMFAAPS). Current from the accelerator was directed by an electron collector or a plasma opening switch through a thin aluminum film, which exploded to form the anode plasma.« less

Electrolyte for an electrochemical cell

DOEpatents

Bates, John B.; Dudney, Nancy J.

1997-01-01

Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte amorphous lithium phosphorus oxynitride which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

Electrolyte for an electrochemical cell

DOEpatents

Bates, J.B.; Dudney, N.J.

1997-01-28

Described is a thin-film battery, especially a thin-film microbattery, and a method for making the same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte amorphous lithium phosphorus oxynitride which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between {minus}15 C and 150 C. 9 figs.

Cathode for an electrochemical cell

DOEpatents

Bates, John B.; Dudney, Nancy J.; Gruzalski, Greg R.; Luck, Christopher F.

2001-01-01

Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode. Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

[Corrosion resistant properties of different anodized microtopographies on titanium surfaces].

PubMed

Fangjun, Huo; Li, Xie; Xingye, Tong; Yueting, Wang; Weihua, Guo; Weidong, Tian

2015-12-01

To investigate the corrosion resistant properties of titanium samples prepared by anodic oxidation with different surface morphologies. Pure titanium substrates were treated by anodic oxidation to obtain porous titanium films in micron, submicron, and micron-submicron scales. The surface morphologies, coating cross-sectional morphologies, crystalline structures, and surface roughness of these samples were characterized. Electrochemical technique was used to measure the corrosion potential (Ecorr), current density of corrosion (Icorr), and polarization resistance (Rp) of these samples in a simulated body fluid. Pure titanium could be modified to exhibit different surface morphologies by the anodic oxidation technique. The Tafel curve results showed that the technique can improve the corrosion resistance of pure titanium. Furthermore, the corrosion resistance varied with different surface morphologies. The submicron porous surface sample demonstrated the best corrosion resistance, with maximal Ecorr and Rp and minimal Icorr. Anodic oxidation technology can improve the corrosion resistance of pure titanium in a simulated body fluid. The submicron porous surface sample exhibited the best corrosion resistance because of its small surface area and thick barrier layer.

Ambient Pressure XPS Study of Mixed Conducting Perovskite-Type SOFC Cathode and Anode Materials under Well-Defined Electrochemical Polarization

PubMed Central

2015-01-01

The oxygen exchange activity of mixed conducting oxide surfaces has been widely investigated, but a detailed understanding of the corresponding reaction mechanisms and the rate-limiting steps is largely still missing. Combined in situ investigation of electrochemically polarized model electrode surfaces under realistic temperature and pressure conditions by near-ambient pressure (NAP) XPS and impedance spectroscopy enables very surface-sensitive chemical analysis and may detect species that are involved in the rate-limiting step. In the present study, acceptor-doped perovskite-type La0.6Sr0.4CoO3-δ (LSC), La0.6Sr0.4FeO3-δ (LSF), and SrTi0.7Fe0.3O3-δ (STF) thin film model electrodes were investigated under well-defined electrochemical polarization as cathodes in oxidizing (O2) and as anodes in reducing (H2/H2O) atmospheres. In oxidizing atmosphere all materials exhibit additional surface species of strontium and oxygen. The polaron-type electronic conduction mechanism of LSF and STF and the metal-like mechanism of LSC are reflected by distinct differences in the valence band spectra. Switching between oxidizing and reducing atmosphere as well as electrochemical polarization cause reversible shifts in the measured binding energy. This can be correlated to a Fermi level shift due to variations in the chemical potential of oxygen. Changes of oxidation states were detected on Fe, which appears as FeIII in oxidizing atmosphere and as mixed FeII/III in H2/H2O. Cathodic polarization in reducing atmosphere leads to the reversible formation of a catalytically active Fe0 phase. PMID:26877827

Electrochemical Analysis of Conducting Polymer Thin Films

PubMed Central

Vyas, Ritesh N.; Wang, Bin

2010-01-01

Polyelectrolyte multilayers built via the layer-by-layer (LbL) method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material by means of electrostatic interaction. The thickness of the adsorbed layers can be tuned precisely in the nanometer range. Stable, semiconducting thin films are interesting research subjects. We use a conducting polymer, poly(p-phenylene vinylene) (PPV), in the preparation of a stable thin film via the LbL method. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize the ionic conductivity of the PPV multilayer films. The ionic conductivity of the films has been found to be dependent on the polymerization temperature. The film conductivity can be fitted to a modified Randle’s circuit. The circuit equivalent calculations are performed to provide the diffusion coefficient values. PMID:20480052

Evaluation of AA5052 alloy anode in alkaline electrolyte with organic rare-earth complex additives for aluminium-air batteries

NASA Astrophysics Data System (ADS)

Wang, Dapeng; Li, Heshun; Liu, Jie; Zhang, Daquan; Gao, Lixin; Tong, Lin

2015-10-01

Behaviours of the AA5052 aluminium alloy anode of the alkaline aluminium-air battery are studied by the hydrogen evolution test, the electrochemical measurements and the surface analysis method. The combination of amino-acid and rare earth as electrolyte additives effectively retards the self-corrosion of AA5052 aluminium alloy in 4 M NaOH solution. It shows that the combination of L-cysteine and cerium nitrate has a synergistic effect owing to the formation of a complex film on AA5052 alloy surface. The organic rare-earth complex can decrease the anodic polarisation, suppress the hydrogen evolution and increase the anodic utilization rate.

Effect of crystallographic orientation on the anodic formation of nanoscale pores/tubes in TiO 2 films

NASA Astrophysics Data System (ADS)

Kalantar-zadeh, K.; Sadek, A. Z.; Zheng, H.; Partridge, J. G.; McCulloch, D. G.; Li, Y. X.; Yu, X. F.; Wlodarski, W.

2009-10-01

Self-organized nanopores and nanotubes have been produced in thin films of titanium (Ti) prepared using filtered cathodic vacuum arc (FCVA), DC- and RF-sputter deposition systems. The anodization process was performed using a neutral electrolyte containing fluoride ions with an applied potential between 2 and 20 V (for clarity the results are only presented for 5 V). Scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques were used to characterise the films. It was found that the crystallographic orientation of the Ti films played a significant role in determining whether pores or tubes were formed during the anodic etching process.

Photo-electrochemical Oxidation of Organic C1 Molecules over WO3 Films in Aqueous Electrolyte: Competition Between Water Oxidation and C1 Oxidation.

PubMed

Reichert, Robert; Zambrzycki, Christian; Jusys, Zenonas; Behm, R Jürgen

2015-11-01

To better understand organic-molecule-assisted photo-electrochemical water splitting, photo-electrochemistry and on-line mass spectrometry measurements are used to investigate the photo-electrochemical oxidation of the C1 molecules methanol, formaldehyde, and formic acid over WO3 film anodes in aqueous solution and its competition with O2 evolution from water oxidation O2 (+) and CO2 (+) ion currents show that water oxidation is strongly suppressed by the organic species. Photo-electro-oxidation of formic acid is dominated by formation of CO2 , whereas incomplete oxidation of formaldehyde and methanol prevails, with the selectivity for CO2 formation increasing with increasing potential and light intensity. The mechanistic implications for the photo-electro-oxidation of the organic molecules and its competition with water oxidation, which could be derived from this novel approach, are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structure and Reactivity of Alucone-Coated Films on Si and Li(x)Si(y) Surfaces.

PubMed

Ma, Yuguang; Martinez de la Hoz, Julibeth M; Angarita, Ivette; Berrio-Sanchez, Jose M; Benitez, Laura; Seminario, Jorge M; Son, Seoung-Bum; Lee, Se-Hee; George, Steven M; Ban, Chunmei; Balbuena, Perla B

2015-06-10

Coating silicon particles with a suitable thin film has appeared as a possible solution to accommodate the swelling of silicon upon lithiation and its posterior cracking and pulverization during cycling of Li-ion batteries. In particular, aluminum alkoxide (alucone) films have been recently deposited over Si anodes, and the lithiation and electrochemical behavior of the system have been characterized. However, some questions remain regarding the lithium molecular migration mechanisms through the film and the electronic properties of the alucone film. Here we use density functional theory, ab initio molecular dynamics simulations, and Green's function theory to examine the film formation, lithiation, and reactivity in contact with an electrolyte solution. It is found that the film is composed of Al-O complexes with 3-O or 4-O coordination. During lithiation, Li atoms bind very strongly to the O atoms in the most energetically favorable sites. After the film is irreversibly saturated with Li atoms, it becomes electronically conductive. The ethylene carbonate molecules in liquid phase are found to be reduced at the surface of the Li-saturated alucone film following similar electron transfer mechanisms as found previously for lithiated silicon anodes. The theoretical results are in agreement with those from morphology and electrochemical analyses.

Plasmon-induced optical switching of electrical conductivity in porous anodic aluminum oxide films encapsulated with silver nanoparticle arrays.

PubMed

Huang, Chen-Han; Lin, Hsing-Ying; Lau, Ben-Chao; Liu, Chih-Yi; Chui, Hsiang-Chen; Tzeng, Yonhua

2010-12-20

We report on plasmon induced optical switching of electrical conductivity in two-dimensional (2D) arrays of silver (Ag) nanoparticles encapsulated inside nanochannels of porous anodic aluminum oxide (AAO) films. The reversible switching of photoconductivity greatly enhanced by an array of closely spaced Ag nanoparticles which are isolated from each other and from the ambient by thin aluminum oxide barrier layers are attributed to the improved electron transport due to the localized surface plasmon resonance and coupling among Ag nanoparticles. The photoconductivity is proportional to the power, and strongly dependent on the wavelength of light illumination. With Ag nanoparticles being isolated from the ambient environments by a thin layer of aluminum oxide barrier layer of controlled thickness in nanometers to tens of nanometers, deterioration of silver nanoparticles caused by environments is minimized. The electrochemically fabricated nanostructured Ag/AAO is inexpensive and promising for applications to integrated plasmonic circuits and sensors.

Formation of multicomponent matrix metal oxide films in anodic alumina matrixes by chemical deposition

NASA Astrophysics Data System (ADS)

Gorokh, G. G.; Zakhlebayeva, A. I.; Metla, A. I.; Zhilinskiy, V. V.; Murashkevich, A. N.; Bogomazova, N. V.

2017-11-01

The metal oxide films of SnxZnyOz and SnxMoyOz systems deposited onto anodic alumina matrixes by chemical and ion layering from an aqueous solutions were characterized by scanning electron microscopy, Raman spectroscopy, electron probe X-ray microanalysis and IR spectroscopy. The obtained matrix films had reproducible composition and structure and possessed certain morphological characteristics and properties.

Synthesis and electrochemical performances of amorphous carbon-coated Sn Sb particles as anode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, Zhong; Tian, Wenhuai; Liu, Xiaohe; Yang, Rong; Li, Xingguo

2007-12-01

The amorphous carbon coating on the Sn-Sb particles was prepared from aqueous glucose solutions using a hydrothermal method. Because the outer layer carbon of composite materials is loose cotton-like and porous-like, it can accommodate the expansion and contraction of active materials to maintain the stability of the structure, and hinder effectively the aggregation of nano-sized alloy particles. The as-prepared composite materials show much improved electrochemical performances as anode materials for lithium-ion batteries compared with Sn-Sb alloy and carbon alone. This amorphous carbon-coated Sn-Sb particle is extremely promising anode materials for lithium secondary batteries and has a high potentiality in the future use.

Selectivity control of carbonylation of methanol to dimethyl oxalate and dimethyl carbonate over gold anode by electrochemical potential.

PubMed

Funakawa, Akiyasu; Yamanaka, Ichiro; Takenaka, Sakae; Otsuka, Kiyoshi

2004-05-05

New and unique electrocatalysis of gold for the carbonylation of methanol to dimethyl oxalate (DMO) and dimethyl carbonate (DMC) was found. The selectivity to DMO and DMC could be controlled over gold anode by electrochemical potential, as you like. Drastic changes of gold electrocatalysis was due to changes of the oxidation state of gold, Au0 or Au3+.

Uneven biofilm and current distribution in three-dimensional macroporous anodes of bio-electrochemical systems composed of graphite electrode arrays.

PubMed

Li, Jun; Hu, Linbin; Zhang, Liang; Ye, Ding-Ding; Zhu, Xun; Liao, Qiang

2017-03-01

A 3-D macroporous anode was constructed using different numbers of graphite rod arrays in fixed-volume bio-electrochemical systems (BESs), and the current and biofilm distribution were investigated by dividing the 3-D anode into several subunits. In the fixed-volume chamber, current production was not significantly improved after the electrode number increased to 36. In the case of 100 electrodes, a significant uneven current distribution was found in the macroporous anode. This was attributed to a differential pH distribution, which resulted from proton accumulation inside the macroporous anode. The pH distribution influenced the biofilm development and led to an uneven biofilm distribution. With respect to current generation, the uneven distribution of both the pH and biofilm contributed to the uneven current distribution. The center had a low pH, which led to less biofilm and a lower contribution to the total current, limiting the performance of the BESs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fullerene C60 coated silicon nanowires as anode materials for lithium secondary batteries.

PubMed

Arie, Arenst Andreas; Lee, Joong Kee

2012-04-01

A Fullerene C60 film was introduced as a coating layer for silicon nanowires (Si NWs) by a plasma assisted thermal evaporation technique. The morphology and structural characteristics of the materials were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). SEM observations showed that the shape of the nanowire structure was maintained after the C60 coating and the XPS analysis confirmed the presence of the carbon coating layer. The electrochemical characteristics of C60 coated Si NWs as anode materials were examined by charge-discharge tests and electrochemical impedance measurements. With the C60 film coating, Si NW electrodes exhibited a higher initial coulombic efficiency of 77% and a higher specific capacity of 2020 mA h g(-1) after the 30th cycle at a current density of 100 microA cm(-2) with cut-off voltage between 0-1.5 V. These improved electrochemical characteristics are attributed to the presence of the C60 coating layer which suppresses side reaction with the electrolyte and maintains the structural integrity of the Si NW electrodes during cycle tests.

Electrochemical stability and corrosion resistance of Ti-Mo alloys for biomedical applications.

PubMed

Oliveira, N T C; Guastaldi, A C

2009-01-01

Electrochemical behavior of pure Ti and Ti-Mo alloys (6-20wt.% Mo) was investigated as a function of immersion time in electrolyte simulating physiological media. Open-circuit potential values indicated that all Ti-Mo alloys studied and pure Ti undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the chloride-containing solution. It also indicated that the addition of Mo to pure Ti up to 15wt.% seems to improve the protection characteristics of its spontaneous oxides. Electrochemical impedance spectroscopy (EIS) studies showed high impedance values for all samples, increasing with immersion time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film present on the metals' surface, improving their resistance with immersion time, presenting the highest values to Ti-15Mo alloy. Potentiodynamic polarization showed a typical valve-metal behavior, with anodic formation of barrier-type oxide films, without pitting corrosion, even in chloride-containing solution. In all cases, the passive current values were quite small, and decrease after 360h of immersion. All these electrochemical results suggest that the Ti-15Mo alloy is a promising material for orthopedic devices, since electrochemical stability is directly associated with biocompatibility and is a necessary condition for applying a material as biomaterial.

A novel in situ electrochemical NMR cell with a palisade gold film electrode

NASA Astrophysics Data System (ADS)

Ni, Zu-Rong; Cui, Xiao-Hong; Cao, Shuo-Hui; Chen, Zhong

2017-08-01

In situ electrochemical nuclear magnetic resonance (EC-NMR) has attracted considerable attention because of its ability to directly observe real-time electrochemical processes. Therefore, minimizing the incompatibility between the electrochemical device and NMR detection has become an important challenge. A circular thin metal film deposited on the outer surface of a glass tube with a thickness considerably less than the metal skin depth is considered to be the ideal working electrode. In this study, we demonstrate that such a thin film electrode still has a great influence on the radio frequency field homogeneity in the detective zone of the NMR spectrometer probe and provide theoretical and experimental confirmation of its electromagnetic shielding. Furthermore, we propose a novel palisade gold film device to act as the working electrode. The NMR nutation behavior of protons shows that the uniformity of the radio frequency field is greatly improved, increasing the sensitivity in NMR detection. Another advantage of the proposed device is that an external reference standard adapted to the reaction compound can be inserted as a probe to determine the fluctuation of the physico-chemical environment and achieve high-accuracy quantitative NMR analysis. A three-chamber electrochemical device based on the palisade gold film design was successfully fabricated and the in situ electrochemical NMR performance was validated in a standard 5 mm NMR probe by acquiring voltammograms and high-resolution NMR spectra to characterize the electrochemically generated species. The evolution of in situ EC-NMR spectrum monitoring of the redox transformation between p-benzoquinone and hydroquinone demonstrates the ability of the EC-NMR device to simultaneously quantitatively determine the reactants and elucidate the reaction mechanism at the molecular level.

Carbon foam anode modified by urea and its higher electrochemical performance in marine benthic microbial fuel cell

NASA Astrophysics Data System (ADS)

Fu, Yubin; Lu, Zhikai; Zai, Xuerong; Wang, Jian

2015-08-01

Electrode materials have an important effect on the property of microbial fuel cell (MFC). Carbon foam is utilized as an anode and further modified by urea to improve its performance in marine benthic microbial fuel cell (BMFC) with higher voltage and output power. The electrochemical properties of plain carbon foam (PC) and urea-modified carbon foam (UC) are measured respectively. Results show that the UC obtains better wettability after its modification and higher anti-polarization ability than the PC. A novel phenomenon has been found that the electrical potential of the modified UC anode is nearly 100 mV lower than that of the PC, reaching -570 ±10 mV ( vs. SCE), and that it also has a much higher electron transfer kinetic activity, reaching 9399.4 mW m-2, which is 566.2-fold higher than that from plain graphite anode (PG). The fuel cell containing the UC anode has the maximum power density (256.0 mW m-2) among the three different BMFCs. Urea would enhance the bacteria biofilm formation with a more diverse microbial community and maintain more electrons, leading to a lower anodic redox potential and higher power output. The paper primarily analyzes why the electrical potential of the modified anode becomes much lower than that of others after urea modification. These results can be utilized to construct a novel BMFC with higher output power and to design the conditioner of voltage booster with a higher conversion ratio. Finally, the carbon foam with a bigger pore size would be a potential anodic material in conventional MFC.

Improving the direct electron transfer in monolithic bioelectrodes prepared by immobilization of FDH enzyme on carbon-coated anodic aluminum oxide films

NASA Astrophysics Data System (ADS)

Castro-Muñiz, Alberto; Hoshikawa, Yasuto; Komiyama, Hiroshi; Nakayama, Wataru; Itoh, Tetsuji; Kyotani, Takashi

2016-02-01

The present work reports the preparation of binderless carbon-coated porous films and the study of their performance as monolithic bioanodes. The films were prepared by coating anodic aluminum oxide (AAO) films with a thin layer of nitrogen-doped carbon by chemical vapor deposition. The films have cylindrical straight pores with controllable diameter and length. These monolithic films were used directly as bioelectrodes by loading the films with D-fructose dehydrogenase (FDH), an oxidoreductase enzyme that catalyzes the oxidation of D-fructose to 5-keto-D-fructose. The immobilization of the enzymes was carried out by physical adsorption in liquid phase and with an electrostatic attraction method. The latter method takes advantage of the fact that FDH is negatively charged during the catalytic oxidation of fructose. Thus the immobilization was performed under the application of a positive voltage to the CAAO film in a FDH-fructose solution in McIlvaine buffer (pH 5) at 25 ºC. As a result, the FDH modified electrodes with the latter method show much better electrochemical response than that with the conventional physical adsorption method. Due to the singular porous structure of the monolithic films, which consists of an array of straight and parallel nanochannels, it is possible to rule out the effect of the diffusion of the D-fructose into the pores. Thus the improvement in the performance upon using the electrostatic attraction method can be ascribed not only to a higher uptake, but also to a more appropriate molecule orientation of the enzyme units on the surface of the electrodes.

Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires

NASA Astrophysics Data System (ADS)

Chi, Su (Ike); Farias, Stephen; Cammarata, Robert

2013-03-01

Tellurium alloys are characterized by their high performance thermoelectric properties and recent research has shown nanostructured tellurium alloys display even greater performance than bulk equivalents. Increased thermoelectric efficiency of nanostructured materials have led to significant interests in developing thin film and nanowire structures. Here, we report on the first successful electrodeposition of lanthanum telluride thin films and nanowires. The electrodeposition of lanthanum telluride thin films is performed in ionic liquids at room temperature. The synthesis of nanowires involves electrodepositing lanthanum telluride arrays into anodic aluminum oxide (AAO) nanoporous membranes. These novel procedures can serve as an alternative means of simple, inexpensive and laboratory-environment friendly methods to synthesize nanostructured thermoelectric materials. The thermoelectric properties of thin films and nanowires will be presented to compare to current state-of-the-art thermoelectric materials. The morphologies and chemical compositions of the deposited films and nanowires are characterized using SEM and EDAX analysis.

Effect of substrate surface treatment on electrochemically assisted photocatalytic activity of N-S co-doped TiO2 films

NASA Astrophysics Data System (ADS)

Parada-Gamboa, N. J.; Pedraza-Avella, J. A.; Meléndez, A. M.

2017-01-01

To investigate whether different metal surface treatments, performed on meshes of stainless steel 304 and titanium, affect the photocatalytic activity (PCA) of supported modified anodic TiO2 films, metallic substrates were coated with titanium isopropoxide sol-gel precursor modified with thiourea. Substrates were pretreated by some of the following techniques: a) sandblasting, b) pickling, c) hydroxylation and d) passivation. The as-prepared electrode materials were characterized by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and voltammetry in the dark and under light UVA irradiation. PCA of modified N-S-TiO2 electrodes was evaluated by electrochemically assisted photocatalytic degradation of methyl orange. The results of XPS revealed that N and S were incorporated into the lattice of TiO2. FESEM showed that surface roughness and thickness of films varies depending on surface treatment. Voltammetric and XPS characterization of N-S co-doped TiO2 films supported on stainless steel revealed that their surface contains alpha-Fe2O3/FeOOH. Accordingly, iron contamination of the films coming from stainless steel was detrimental to the degradation of methyl orange. Prior to sol-gel coating process, sandblasting followed by nitric acid passivation for stainless steel or hydrofluoric acid pickling process in the case of titanium improved the PCA of N-S co-doped TiO2 films.

The Effect of Silane on the Microstructure, Corrosion, and Abrasion Resistances of the Anodic Films on Ti Alloy

NASA Astrophysics Data System (ADS)

Wang, Jinwei; Chen, Jiali

2016-04-01

Anodic oxide films on Ti-6Al-4V alloy are prepared using sodium hydroxide as the base electrolyte containing aminopropyl trimethoxysilane (APS) as an additive. Some APS undergo hydrolysis, adsorption, and chemical reaction with the TiO x to form Ti-O-Si bond as confirmed by ATR-FTIR and XPS spectra, and in turn their surface appearance and roughness are greatly changed with the addition of APS as observed by their SEM images. These amino anodic films possess much higher corrosive resistances since the formation of Ti-O-Si complex enhances the compactness of the anodic films and the existence of aminopropyl groups inside the pores provides additional blocking effects. Besides, their improvement in anti-abrasive capability is attributed to the toughening effect of the chemically bonded silanes and the lubrication functions from both the chemically bonded and physically absorbed silanes between the touched interfaces.

The effect of grain size on aluminum anodes for Al-air batteries in alkaline electrolytes

NASA Astrophysics Data System (ADS)

Fan, Liang; Lu, Huimin

2015-06-01

Aluminum is an ideal material for metallic fuel cells. In this research, different grain sizes of aluminum anodes are prepared by equal channel angular pressing (ECAP) at room temperature. Microstructure of the anodes is examined by electron backscatter diffraction (EBSD) in scanning electron microscope (SEM). Hydrogen corrosion rates of the Al anodes in 4 mol L-1 NaOH are determined by hydrogen collection method. The electrochemical properties of the aluminum anodes are investigated in the same electrolyte using electrochemical impedance spectroscopy (EIS) and polarization curves. Battery performance is also tested by constant current discharge at different current densities. Results confirm that the electrochemical properties of the aluminum anodes are related to grain size. Finer grain size anode restrains hydrogen evolution, improves electrochemical activity and increases anodic utilization rate. The proposed method is shown to effectively improve the performance of Al-air batteries.

All-Ceramic Thin Film Battery

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

BOYLE, TIMOTHY J.; INGERSOLL, DAVID; CYGAN, RANDALL T.

2002-11-01

We have undertaken the synthesis of a thin film ''All Ceramic Battery'' (ACB) using solution route processes. Based on the literature and experimental results, we selected SnO{sub 2}, LiCoO{sub 2}, and LiLaTiO{sub 3} (LLT) as the anode, cathode, and electrolyte, respectively. Strain induced by lattice mismatch between the cathode and bottom electrode, as estimated by computational calculations, indicate that thin film orientations for batteries when thicknesses are as low as 500 {angstrom} are strongly controlled by surface energies. Therefore, we chose platinized silicon as the basal platform based on our previous experience with this material. The anode thin films weremore » generated by standard spin-cast methods and processing using a solution of [Sn(ONep)]{sub 8} and HOAc which was found to form Sn{sub 6}(O){sub 4}(ONep){sub 4}. Electrochemical evaluation showed that the SnO{sub 2} was converted to Sn{sup o} during the first cycle. The cathode was also prepared by spin coating using the novel [Li(ONep)]{sub 8} and Co(OAc){sub 2}. The films could be electrochemically cycled (i.e., charged/discharged), with all of the associated structural changes being observable by XRD. Computational models indicated that the LLT electrolyte would be the best available ceramic material for use as the electrolyte. The LLT was synthesized from [Li(ONep)]{sub 8}, [Ti(ONep){sub 4}]{sub 2}, and La(DIP){sub 3}(py){sub 3} with RTP processing at 900 C being necessary to form the perovskite phase. Alternatively, a novel route to thin films of the block co-polymer ORMOLYTE was developed. The integration of these components was undertaken with each part of the assembly being identifiably by XRD analysis (this will allow us to follow the progress of the charge/discharge cycles of the battery during use). SEM investigations revealed the films were continuous with minimal mixing. All initial testing of the thin-film cathode/electrolyte/anode ACB devices revealed electrical shorting

A biohydrogen fuel cell using a conductive polymer nanocomposite based anode.

PubMed

Hoa, Le Quynh; Sugano, Yasuhito; Yoshikawa, Hiroyuki; Saito, Masato; Tamiya, Eiichi

2010-07-15

This paper introduces a newly designed biohydrogen fuel cell by integrating a bioreactor for hydrogen production with the anode chamber in a hydrogen fuel cell. Two different composites of platinum nanoparticles decorated on functionalised multi-walled carbon nanotubes (Pt/fMWCNTs) and polyaniline (PANI) were fabricated using the electrochemical polymerisation method and used as anodes. The biohydrogen fuel cell using a thin film of PANI nanofibres deposited on Pt/fMWCNTs/carbon paper as the anode showed much higher power density than the cell using a core-shell structure PANI/Pt/fMWCNTs and Pt/fMWCNTs without PANI based anodes. The structural differences between these two composites and their effects on the interaction with hydrogen gas inside the anode chamber leading to the difference in power density of the fuel cell were also discussed. The maximum power density was 613.5 mW m(-2), which was obtained at a current density of about 2.55 A m(-2) with a cell voltage of 0.24 V using 20 mL single-chamber air-cathode, compact biohydrogen fuel cell. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Method for making an electrochemical cell

DOEpatents

Bates, J.B.; Dudney, N.J.

1996-10-22

Described is a thin-film battery, especially a thin-film microbattery, and a method for making the same, having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode. Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between {minus}15 C and 150 C. 9 figs.

Method for making an electrochemical cell

DOEpatents

Bates, John B.; Dudney, Nancy J.

1996-01-01

Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

Polyethylene oxide film coating enhances lithium cycling efficiency of an anode-free lithium-metal battery.

PubMed

Assegie, Addisu Alemayehu; Cheng, Ju-Hsiang; Kuo, Li-Ming; Su, Wei-Nien; Hwang, Bing-Joe

2018-03-29

The practical implementation of an anode-free lithium-metal battery with promising high capacity is hampered by dendrite formation and low coulombic efficiency. Most notably, these challenges stem from non-uniform lithium plating and unstable SEI layer formation on the bare copper electrode. Herein, we revealed the homogeneous deposition of lithium and effective suppression of dendrite formation using a copper electrode coated with a polyethylene oxide (PEO) film in an electrolyte comprising 1 M LiTFSI, DME/DOL (1/1, v/v) and 2 wt% LiNO3. More importantly, the PEO film coating promoted the formation of a thin and robust SEI layer film by hosting lithium and regulating the inevitable reaction of lithium with the electrolyte. The modified electrode exhibited stable cycling of lithium with an average coulombic efficiency of ∼100% over 200 cycles and low voltage hysteresis (∼30 mV) at a current density of 0.5 mA cm-2. Moreover, we tested the anode-free battery experimentally by integrating it with an LiFePO4 cathode into a full-cell configuration (Cu@PEO/LiFePO4). The new cell demonstrated stable cycling with an average coulombic efficiency of 98.6% and capacity retention of 30% in the 200th cycle at a rate of 0.2C. These impressive enhancements in cycle life and capacity retention result from the synergy of the PEO film coating, high electrode-electrolyte interface compatibility, stable polar oligomer formation from the reduction of 1,3-dioxolane and the generation of SEI-stabilizing nitrite and nitride upon lithium nitrate reduction. Our result opens up a new route to realize anode-free batteries by modifying the copper anode with PEO to achieve ever more demanding yet safe interfacial chemistry and control of dendrite formation.

Anodizing Process

NASA Technical Reports Server (NTRS)

1983-01-01

This anodizing process traces its origin to the 1960's when Reynolds Metals Company, under contract with Goddard Space Flight Center, developed a multipurpose anodizing electrolyte (MAE) process to produce a hard protective finish for spacecraft aluminum. MAE produces a high-density, abrasion-resistant film prior to the coloring step, in which the pores of the film are impregnated with a metallic form of salt. Tru-Color product applications include building fronts, railing, curtain walls, doors and windows.

Fabrication and electrochemical performance of nickel- and gadolinium-doped ceria-infiltrated La0·2Sr0·8TiO3 anodes for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Lee, Min-Jin; Shin, Jae-Hwa; Ji, Mi-Jung; Hwang, Hae-Jin

2018-01-01

In this work, nickel and gadolinium-doped ceria (GDC)-infiltrated lanthanum strontium titanate (LST) anodes are fabricated, and their electrode performances under a hydrogen atmosphere is investigated in terms of the Ni:GDC ratios and cell operating temperature. The Ni/GDC-infiltrated LST anode exhibits excellent electrode performance in comparison with the Ni- or GDC-infiltrated anodes, which is attributed to the synergistic effect of an extended triple-phase boundary length by GDC and good catalytic activity for hydrogen oxidation because of the Ni particles. The polarization resistances (Rp) of Ni/GDC-infiltrated LST are 0.07, 0.08, and 0.12 Ω cm2 at 800, 750, and 700 °C, respectively, which are approximately three orders of magnitude lower than that of the LST anode (68.5 Ω cm2 at 700 °C). The effect of Ni and GDC on the electrochemical performance of LST was also investigated by using electrochemical impedance spectroscopy (EIS). The anode polarization resistance (Rp) is confirmed to be dependent on the content and dispersion state (microstructure) of the Ni and GDC nanoparticles.

Enhanced electrochemical performance of monoclinic WO3 thin film with redox additive aqueous electrolyte.

PubMed

Shinde, Pragati A; Lokhande, Vaibhav C; Chodankar, Nilesh R; Ji, Taeksoo; Kim, Jin Hyeok; Lokhande, Chandrakant D

2016-12-01

To achieve the highest electrochemical performance for supercapacitor, it is very essential to find out a suitable pair of an active electrode material and an electrolyte. In the present work, a simple approach is employed to enhance the supercapacitor performance of WO3 thin film. The WO3 thin film is prepared by a simple and cost effective chemical bath deposition method and its electrochemical performance is tested in conventional (H2SO4) and redox additive [H2SO4+hydroquinone (HQ)] electrolytes. Two-fold increment in electrochemical performance for WO3 thin film is observed in redox additive aqueous electrolyte compared to conventional electrolyte. WO3 thin film showed maximum specific capacitance of 725Fg(-1), energy density of 25.18Whkg(-1) at current density of 7mAcm(-2) with better cycling stability in redox electrolyte. This strategy provides the versatile way for designing the high performance energy storage devices. Copyright © 2016 Elsevier Inc. All rights reserved.

Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

NASA Astrophysics Data System (ADS)

Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

2014-12-01

Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices.

Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

PubMed Central

Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

2014-01-01

Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices. PMID:25491282

Local Anodic Oxidation of Thin GeO Films and Formation of Nanostructures Based on Them

NASA Astrophysics Data System (ADS)

Astankova, K. N.; Kozhukhov, A. S.; Azarov, I. A.; Gorokhov, E. B.; Sheglov, D. V.; Latyshev, A. V.

2018-04-01

The process of local anodic oxidation of thin GeO films has been studied using an atomic force microscope. The electron-probe microanalysis showed that oxidized areas of a GeO film were germanium dioxide. The effect of the voltage pulse duration applied to the probe-substrate system and the atmospheric humidity on the height of the oxide structures has been studied. The kinetics of the local anodic oxidation (LAO) in a semi-contact mode obeys the Cabrera-Mott model for large times. The initial growth rate of the oxide ( R 0) significantly increases and the time of starting the oxidation ( t 0) decreases as the atmospheric humidity increases by 20%, which is related to an increase in the concentration of oxygen-containing ions at the surface of the oxidized GeO film. It was shown that nanostructures in thin GeO layers can be formed by the LAO method.

Optical and magnetic properties of porous anodic alumina/Ni nanocomposite films

NASA Astrophysics Data System (ADS)

Zhang, Jing-Jing; Li, Zi-Yue; Zhang, Zhi-Jun; Wu, Tian-Shan; Sun, Hui-Yuan

2013-06-01

A simple method to tune the optical properties of porous anodic alumina (PAA) films embedded with Ni is reported. The films display highly saturated colors after being synthesized by an ac electrodeposition method. The optical properties of the samples can be effectively tuned by varying the oxidation time of aluminum. The ultrashort Ni nanowires (100 nm long and 50 nm in diameter) present only fcc phase and show no apparent averaged effective magnetic anisotropy. The coercivity mechanism of the Ni nanowires in our case is consistent with fanning mechanism based on a chain-of-spheres model. PAA/Ni films with structural color and magnetic properties have friability-resistant feature and can be used in many areas, including decoration, display, and multifunctional anti-counterfeiting technology.

Electrochemical synthesis of self-organized TiO2 crystalline nanotubes without annealing

NASA Astrophysics Data System (ADS)

Giorgi, Leonardo; Dikonimos, Theodoros; Giorgi, Rossella; Buonocore, Francesco; Faggio, Giuliana; Messina, Giacomo; Lisi, Nicola

2018-03-01

This work demonstrates that upon anodic polarization in an aqueous fluoride-containing electrolyte, TiO2 nanotube array films can be formed with a well-defined crystalline phase, rather than an amorphous one. The crystalline phase was obtained avoiding any high temperature annealing. We studied the formation of nanotubes in an HF/H2O medium and the development of crystalline grains on the nanotube wall, and we found a facile way to achieve crystalline TiO2 nanotube arrays through a one-step anodization. The crystallinity of the film was influenced by the synthesis parameters, and the optimization of the electrolyte composition and anodization conditions (applied voltage and time) were carried out. For comparison purposes, crystalline anatase TiO2 nanotubes were also prepared by thermal treatment of amorphous nanotubes grown in an organic bath (ethylene glycol/NH4F/H2O). The morphology and the crystallinity of the nanotubes were studied by field emission gun-scanning electron microscopy (FEG-SEM) and Raman spectroscopy, whereas the electrochemical and semiconducting properties were analyzed by means of linear sweep voltammetry, impedance spectroscopy, and Mott-Schottky plots. X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) allowed us to determine the surface composition and the electronic structure of the samples and to correlate them with the electrochemical data. The optimal conditions to achieve a crystalline phase with high donor concentration are defined.

Structure, Electronic Properties, and Electrochemical Behavior of a Boron-Doped Diamond/Quartz Optically Transparent Electrode.

PubMed

Wächter, Naihara; Munson, Catherine; Jarošová, Romana; Berkun, Isil; Hogan, Timothy; Rocha-Filho, Romeu C; Swain, Greg M

2016-10-26

The morphology, microstructure, chemistry, electronic properties, and electrochemical behavior of a boron-doped nanocrystalline diamond (BDD) thin film grown on quartz were evaluated. Diamond optically transparent electrodes (OTEs) are useful for transmission spectroelectrochemical measurements, offering excellent stability during anodic and cathodic polarization and exposure to a variety of chemical environments. We report on the characterization of a BDD OTE by atomic force microscopy, optical spectroscopy, Raman spectroscopic mapping, alternating-current Hall effect measurements, X-ray photoelectron spectroscopy, and electrochemical methods. The results reported herein provide the first comprehensive study of the relationship between the physical and chemical structure and electronic properties of a diamond OTE and the electrode's electrochemical activity.

Aqueous Solution-Deposited Molybdenum Oxide Films as an Anode Interfacial Layer for Organic Solar Cells.

PubMed

Yi, Qinghua; Zhai, Pengfei; Sun, Yinghui; Lou, Yanhui; Zhao, Jie; Sun, Baoquan; Patterson, Brian; Luo, Hongmei; Zhang, Wenrui; Jiao, Liang; Wang, Haiyan; Zou, Guifu

2015-08-26

In this study, we report the growth of molybdenum oxide (MoOx) film by polymer-assisted deposition (PAD), an environmentally friendly strategy in an aqueous system. The MoOx film has good crystal quality and is dense and smooth. The transparency of the film is >95% in the wavelength range of 300-900 nm. The device based on P3HT:PCBM absorber material was fabricated. The solar cell with PAD-MoOx as an anode interfacial layer exhibits great performance, even better than that of a solar cell with PSS or evaporated MoOx as an anode interfacial layer. More importantly, the solar cells based on the growth of MoOx have a longer term stability than that of solar cells based on PSS. These results demonstrate the aqueous PAD technology provides an alternative strategy not only for the thin films' growth of applied materials but also for the solution processing for the low-cost fabrication of future materials to be applied in the field of solar cells.

Gas permeable electrode for electrochemical system

DOEpatents

Ludwig, F.A.; Townsend, C.W.

1989-09-12

An electrode apparatus is described which is adapted for use in electrochemical systems having an anode compartment and a cathode compartment in which gas and ions are produced and consumed in the compartments during generation of electrical current. The electrode apparatus includes a membrane for separating the anode compartment from the cathode compartment wherein the membrane is permeable to both ions and gas. The cathode and anode for the assembly are provided on opposite sides of the membrane. During use of the membrane-electrode apparatus in electrochemical cells, the gas and ions generated at the cathode or anode migrate through the membrane to provide efficient transfer of gas and ions between the anode and cathode compartments. 3 figs.

Gas permeable electrode for electrochemical system

DOEpatents

Ludwig, Frank A.; Townsend, Carl W.

1989-01-01

An electrode apparatus adapted for use in electrochemical systems having an anode compartment and a cathode compartment in which gas and ions are produced and consumed in the compartments during generation of electrical current. The electrode apparatus includes a membrane for separating the anode compartment from the cathode compartment wherein the membrane is permeable to both ions and gas. The cathode and anode for the assembly are provided on opposite sides of the membrane. During use of the membrane-electrode apparatus in electrochemical cells, the gas and ions generated at the cathode or anode migrate through the membrane to provide efficient transfer of gas and ions between the anode and cathode compartments.

Electrochemical generation of oxygen. 1: The effects of anions and cations on hydrogen chemisorption and anodic oxide film formation on platinum electrode. 2: The effects of anions and cations on oxygen generation on platinum electrode

NASA Technical Reports Server (NTRS)

Huang, C. J.; Yeager, E.; Ogrady, W. E.

1975-01-01

The effects were studied of anions and cations on hydrogen chemisorption and anodic oxide film formation on Pt by linear sweep voltammetry, and on oxygen generation on Pt by potentiostatic overpotential measurement. The hydrogen chemisorption and anodic oxide film formation regions are greatly influenced by anion adsorption. In acids, the strongly bound hydrogen occurs at more cathodic potential when chloride and sulfate are present. Sulfate affects the initial phase of oxide film formation by produced fine structure while chloride retards the oxide-film formation. In alkaline solutions, both strongly and weakly bound hydrogen are influenced by iodide, cyanide, and barium and calcium cations. These ions also influence the oxide film formation. Factors considered to explain these effects are discussed. The Tafel slope for oxygen generation was found to be independent on the oxide thickness and the presence of cations or anions. The catalytic activity indicated by the exchange current density was observed decreasing with increasing oxide layer thickness, only a minor dependence on the addition of certain cations and anions was found.

Electrochemical removal of carbamazepine in water with Ti/PbO2 cylindrical mesh anode.

PubMed

García-Espinoza, J D; Gortáres-Moroyoqui, P; Orta-Ledesma, M T; Drogui, P; Mijaylova-Nacheva, P

2016-01-01

Carbamazepine (CBZ) is one of the most frequently detected organic compounds in the aquatic environment. Due to its bio-persistence and toxicity for humans and the environment its removal has become an important issue. The performance of the electrochemical oxidation process and in situ production of reactive oxygen species (ROS), such as O3 and H2O2, for CBZ removal have been studied using Ti/PbO2 cylindrical mesh anode in the presence of Na2SO4 as supporting electrolyte in a batch electrochemical reactor. In this integrated process, direct oxidation at anode and indirect oxidation by in situ electrogenerated ROS can occur simultaneously. The effect of several factors such as electrolysis time, current intensity, initial pH and oxygen flux was investigated by means of an experimental design methodology, using a 2(4) factorial matrix. CBZ removal of 83.93% was obtained and the most influential parameters turned out to be electrolysis time, current intensity and oxygen flux. Later, the optimal experimental values for CBZ degradation were obtained by means of a central composite design. The best operating conditions, analyzed by Design Expert(®) software, are the following: 110 min of electrolysis at 3.0 A, pH = 7.05 and 2.8 L O2/min. Under these optimal conditions, the model prediction (82.44%) fits very well with the experimental response (83.90 ± 0.8%). Furthermore, chemical oxygen demand decrease was quantified. Our results illustrated significant removal efficiency for the CBZ in optimized condition with second order kinetic reaction.

Preparation of Superhydrophobic Film on Ti Substrate and Its Anticorrosion Property.

PubMed

Zhu, Min; Tang, Wenchuan; Huang, Luyao; Zhang, Dawei; Du, Cuiwei; Yu, Gaohong; Chen, Ming; Chowwanonthapunya, Thee

2017-06-08

Superhydrophobic films were fabricated on a titanium substrate with or without anodizing by using a self-assembling method. Firstly, the pretreatments of mechanical polishing/anodizing or mechanical polishing only were conducted, respectively. Subsequently, the preparation of polydopamine film layer, deposition of nano-silver particles, and post modification of 1H,1H,2H,2H-perfluorodecanethiol were performed on the surface of the pretreated substrate. The surface morphologies, compositions, wettability, and corrosion resistance of the films were investigated with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), water contact angle measurements, and electrochemical tests, respectively. Meanwhile, the effect of the deposition time in the silver nitrate solution on the hydrophobicity of the specimen surface was investigated. The result showed that with the increase of deposition time, the hydrophobic property enhanced gradually. The surface deposited for 7 h exhibited an optimum hydrophobic effect, which was characterized with a large water contact angle (WCA) of 154°, and the surface was rather rough and covered by a relatively uniform layer of micro-nano silver particles. The excellent hydrophobicity was attributed to a rough stratified microstructure along with the low surface energy. The electrochemical measurements showed that the existence of the superhydrophobic film can effectively enhance the corrosion resistance of Ti samples.

Preparation of Superhydrophobic Film on Ti Substrate and Its Anticorrosion Property

PubMed Central

Zhu, Min; Tang, Wenchuan; Huang, Luyao; Zhang, Dawei; Du, Cuiwei; Yu, Gaohong; Chen, Ming; Chowwanonthapunya, Thee

2017-01-01

Superhydrophobic films were fabricated on a titanium substrate with or without anodizing by using a self-assembling method. Firstly, the pretreatments of mechanical polishing/anodizing or mechanical polishing only were conducted, respectively. Subsequently, the preparation of polydopamine film layer, deposition of nano-silver particles, and post modification of 1H,1H,2H,2H-perfluorodecanethiol were performed on the surface of the pretreated substrate. The surface morphologies, compositions, wettability, and corrosion resistance of the films were investigated with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), water contact angle measurements, and electrochemical tests, respectively. Meanwhile, the effect of the deposition time in the silver nitrate solution on the hydrophobicity of the specimen surface was investigated. The result showed that with the increase of deposition time, the hydrophobic property enhanced gradually. The surface deposited for 7 h exhibited an optimum hydrophobic effect, which was characterized with a large water contact angle (WCA) of 154°, and the surface was rather rough and covered by a relatively uniform layer of micro-nano silver particles. The excellent hydrophobicity was attributed to a rough stratified microstructure along with the low surface energy. The electrochemical measurements showed that the existence of the superhydrophobic film can effectively enhance the corrosion resistance of Ti samples. PMID:28772987

Parasitic Currents Caused by Different Ionic and Electronic Conductivities in Fuel Cell Anodes.

PubMed

Schalenbach, Maximilian; Zillgitt, Marcel; Maier, Wiebke; Stolten, Detlef

2015-07-29

The electrodes in fuel cells simultaneously realize electric and ionic conductivity. In the case of acidic polymer electrolytes, the electrodes are typically made of composites of carbon-supported catalyst and Nafion polymer electrolyte binder. In this study, the interaction of the proton conduction, the electron conduction, and the electrochemical hydrogen conversion in such composite electrode materials was examined. Exposed to a hydrogen atmosphere, these composites displayed up to 10-fold smaller resistivities for the proton conduction than that of Nafion membranes. This effect was ascribed to the simultaneously occurring electrochemical hydrogen oxidation and evolution inside the composite samples, which are driven by different proton and electron resistivities. The parasitic electrochemical currents resulting were postulated to occur in the anode of fuel cells with polymer, solid oxide, or liquid alkaline electrolytes, when the ohmic drop of the ion conduction in the anode is higher with the anodic kinetic overvoltage (as illustrated in the graphical abstract). In this case, the parasitic electrochemical currents increase the anodic kinetic overpotential and the ohmic drop in the anode. Thinner fuel cell anodes with smaller ohmic drops for the ion conduction may reduce the parasitic electrochemical currents.

Corrosion protection of copper by polypyrrole film studied by electrochemical impedance spectroscopy and the electrochemical quartz microbalance

NASA Astrophysics Data System (ADS)

Lei, Yanhua; Ohtsuka, Toshiaki; Sheng, Nan

2015-12-01

Polypyrrole (PPy) films were synthesized on copper in solution of sodium di-hydrogen phosphate and phytate for corrosion protection. The protection properties of PPy films were comparatively investigated in NaCl solution. During two months immersion, the PPy film doped with phytate anions, working as a cationic perm-selective membrane, inhibited the dissolution of copper to 1% of bare copper. Differently, the PPy film doped with di-hydrogen phosphate anions, possessing anionic perm-selectivity, was gradually reduced, and inhibited the dissolution to 7.8% of bare copper. Degradation of the PPy films was studied by comparing the electrochemical impedance spectroscopy change at different immersion time and Raman spectra change after immersion.

Aluminum anode for aluminum-air battery - Part II: Influence of In addition on the electrochemical characteristics of Al-Zn alloy in alkaline solution

NASA Astrophysics Data System (ADS)

Park, In-Jun; Choi, Seok-Ryul; Kim, Jung-Gu

2017-07-01

Effects of Zn and In additions on the aluminum anode for Al-air battery in alkaline solution are examined by the self-corrosion rate, cell voltage, current-voltage characteristics, anodic polarization, discharge performance and AC impedance measurements. The passivation behavior of Zn-added anode during anodic polarization decreases the discharge performance of Al-air battery. The addition of In to Al-Zn anode reduces the formation of Zn passivation film by repeated adsorption and desorption behavior of In ion onto anode surface. The attenuated Zn passive layer by In ion attack leads to the improvement of discharge performance of Al-air battery.

Plasma-deposited fluoropolymer film mask for local porous silicon formation

PubMed Central

2012-01-01

The study of an innovative fluoropolymer masking layer for silicon anodization is proposed. Due to its high chemical resistance to hydrofluoric acid even under anodic bias, this thin film deposited by plasma has allowed the formation of deep porous silicon regions patterned on the silicon wafer. Unlike most of other masks, fluoropolymer removal after electrochemical etching is rapid and does not alter the porous layer. Local porous regions were thus fabricated both in p+-type and low-doped n-type silicon substrates. PMID:22734507

Electrochemical cell structure and method of making the same

DOEpatents

Schick, Louis Andrew; Libby, Cara Suzanne; Bowen, John Henry; Bourgeois, Richard Scott

2012-09-25

An electrochemical cell structure is provided which includes an anode, a cathode spaced apart from said anode, an electrolyte in ionic communication with each of said anode and said cathode and a nonconductive frame. The nonconductive frame includes at least two components that support each of said anode, said cathode and said electrolyte and define at least one flowpath for working fluids and for products of electrochemical reaction.

In situ fabrication of green reduced graphene-based biocompatible anode for efficient energy recycle.

PubMed

Cheng, Ying; Mallavarapu, Megharaj; Naidu, Ravi; Chen, Zuliang

2018-02-01

Improving the anode configuration to enhance biocompatibility and accelerate electron shuttling is critical for efficient energy recovery in microbial fuel cells (MFCs). In this paper, green reduced graphene nanocomposite was successfully coated using layer-by-layer assembly technique onto carbon brush anode. The modified anode achieved a 3.2-fold higher power density of 33.7 W m -3 at a current density of 69.4 A m -3 with a 75% shorter start period. As revealed in the characterization, the green synthesized nanocomposite film affords larger surface roughness for microbial colonization. Besides, gold nanoparticles, which anchored on graphene sheets, promise the relatively high electroactive sites and facilitate electron transfer from electricigens to the anode. The reduction-oxidation peaks in cyclic voltammograms indicated the mechanism of surface cytochromes facilitated current generation while the electrochemical impedance spectroscopy confirmed the enhanced electron transfer from surface cytochrome to electrode. The green synthesis process has the potential to generate a high performing anode in further applications of MFCs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrochemical synthesis of Sm2O3 nanoparticles: Application in conductive polymer composite films for supercapacitors.

PubMed

Mohammad Shiri, Hamid; Ehsani, Ali; Jalali Khales, Mina

2017-11-01

A novel electrosynthetic method was introduced to synthesize of Sm 2 O 3 nanoparticles and furthermore, for improving the electrochemical performance of conductive polymer, hybrid POAP/Sm 2 O 3 films have then been fabricated by POAP electropolymerization in the presence of Sm 2 O 3 nanoparticles as active electrodes for electrochemical supercapacitors. The structure, morphology, chemical composition of Sm 2 O 3 nanoparticles was examined. Surface and electrochemical analyses have been used for characterization of Sm 2 O 3 and POAP/Sm 2 O 3 composite films. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance. The supercapacity behavior of the composite film was attributed to the (i) high active surface area of the composite, (ii) charge transfer along the polymer chain due to the conjugation form of the polymer and finally (iii) synergism effect between conductive polymer and Sm 2 O 3 nanoparticles. Copyright © 2017 Elsevier Inc. All rights reserved.

Co9 S8 /Co as a High-Performance Anode for Sodium-Ion Batteries with an Ether-Based Electrolyte.

PubMed

Zhao, Yingying; Pang, Qiang; Wei, Yingjin; Wei, Luyao; Ju, Yanming; Zou, Bo; Gao, Yu; Chen, Gang

2017-12-08

Co 9 S 8 has been regarded as a desirable anode material for sodium-ion batteries because of its high theoretical capacity. In this study, a Co 9 S 8 anode material containing 5.5 wt % Co (Co 9 S 8 /Co) was prepared by a solid-state reaction. The electrochemical properties of the material were studied in carbonate and ether-based electrolytes (EBE). The results showed that the material had a longer cycle life and better rate capability in EBE. This excellent electrochemical performance was attributed to a low apparent activation energy and a low overpotential for Na deposition in EBE, which improved the electrode kinetic properties. Furthermore, EBE suppressed side reactions of the electrode and electrolyte, which avoided the formation of a solid electrolyte interphase film. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and electrochemical properties of Ti-doped DLC films by a hybrid PVD/PECVD process

NASA Astrophysics Data System (ADS)

Jo, Yeong Ju; Zhang, Teng Fei; Son, Myoung Jun; Kim, Kwang Ho

2018-03-01

Low electrical conductivity and poor adhesion to metallic substrates are the main drawbacks of diamond-like carbon (DLC) films when used in electrode applications. In this study, Ti-doped DLC films with various Ti contents were synthesized on metal Ti substrates by a hybrid PVD/PECVD process, where PECVD was used for deposition of DLC films and PVD was used for Ti doping. The effects of the Ti doping ratio on the microstructure, adhesion strength, and electrical and electrochemical properties of the DLC films were systematically investigated. An increase in the Ti content led to increased surface roughness and a higher sp2/sp3 ratio of the Ti-DLC films. Ti atoms existed as amorphous-phase Ti carbide when the Ti doping ratio was less than 2.8 at.%, while the nanocrystalline TiC phase was formed in DLC films when the Ti doping ratio was exceeded 4.0 at.%. The adhesion strength, electrical resistivity, electrochemical activity and reversibility of the DLC films were greatly improved by Ti doping. The influence of Ti doping ratio on the electrical and electrochemical properties of the DLC films were also investigated and the best performance was obtained at a Ti content of 2.8 at.%.

Electrochemical and microstructural characterization of magnetron-sputtered ATO thin films as Li–ion storage materials

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

Ouyang, Pan; Zhang, Hong; Chen, Wenhao

2015-01-15

Highlights: • Nano-structured ATO thin films prepared by RF magnetron sputtering at 25 °C, 100 °C and 200 °C, respectively. • ATO thin films show a high reversible capacity and high rate performance. • Electrochemical reaction mechanism of the ATO thin film was revealed by transmission electron microscopy. - Abstract: Sb-doped SnO{sub 2} (ATO) nanostructured thin films were prepared by using radio frequency magnetron sputtering at the substrate temperatures of 25 °C, 100 °C and 200 °C, respectively. All the ATO thin films have the similar redox characteristics in the cyclic voltammetry measurements. The ATO thin film sputtered at 200more » °C shows the lowest charge transfer resistance and best electrochemical performance, and has a high reversible capacity of 679 mA h g{sup −1} at 100 mA g{sup −1} after 200 charge–discharge cycles and high rate performance of 483 mA h g{sup −1} at 800 mA g{sup −1}. The electrochemical mechanisms were investigated by analyzing the phase evolution of the ATO electrodes that had been electrochemically induced at various stages. The results reveal that the ATO underwent reversible lithiation/delithiation processes during the electrochemical cycles, i.e., the SnO{sub 2} reacted with Li{sup +} to produce metallic Sn and followed by the formation of the Li{sub x}Sn alloys during discharge process, and then Li{sub x}Sn alloys de-alloyed, Sn reacted with Li{sub 2}O, and even partially formed SnO{sub 2} during charge process.« less

The role of stress in self-ordered porous anodic oxide formation and corrosion of aluminum

NASA Astrophysics Data System (ADS)

Capraz, Omer Ozgur

The phenomenon of plastic flow induced by electrochemical reactions near room temperature is significant in porous anodic oxide (PAO) films, charging of lithium batteries and stress-corrosion cracking (SCC). As this phenomenon is poorly understood, fundamental insight into flow from our work may provide useful information for these problems. In-situ monitoring of the stress state allows direct correlation between stress and the current or potential, thus providing fundamental insight into technologically important deformation and failure mechanisms induced by electrochemical reactions. A phase-shifting curvature interferometry was designed to investigate the stress generation mechanisms on different systems. Resolution of our curvature interferometry was found to be ten times more powerful than that obtained by state-of-art multiple deflectometry technique and the curvature interferometry helps to resolve the conflicting reports in the literature. During this work, formation of surface patterns during both aqueous corrosion of aluminum and formation of PAO films were investigated. Interestingly, for both cases, stress induced plastic flow controls the formation of surface patterns. Pore formation mechanisms during anodizing of the porous aluminum oxide films was investigated . PAO films are formed by the electrochemical oxidation of metals such as aluminum and titanium in a solution where oxide is moderately soluble. They have been used extensively to design numerous devices for optical, catalytic, and biological and energy related applications, due to their vertically aligned-geometry, high-specific surface area and tunable geometry by adjusting process variables. These structures have developed empirically, in the absence of understanding the process mechanism. Previous experimental studies of anodizing-induced stress have extensively focused on the measurement of average stress, however the measurement of stress evolution during anodizing does not provide

Gold-carbon composite thin films for electrochemical gas sensor prepared by reactive plasma sputtering

NASA Astrophysics Data System (ADS)

Okamoto, A.; Suzuki, Y.; Yoshitake, M.; Ogawa, S.; Nakano, N.

1997-01-01

We have investigated the properties of gold-carbon composite thin films prepared by a plasma sputtering deposition using argon and methane mixture gas. These composite films have an uneven surface in submicron scale or consist of nano-scale particles of gold polycrystalline. Such morphological properties can be controlled by the sputtering voltage and the partial pressure of methane gas. The working electrode of electrochemical gas sensor has needed a stable gas sensitivity and a good gas selectivity. Our composite film is one of the excellent candidates for a thin film working electrode of electrochemical gas sensor. It is described that the output current of sensor is related to the preparation conditions of the thin films and increase linearly as the concentration of PH 3 gas ranging from 0.1 to 1.0 ppm is increasing.

Preparation and analysis of anodic aluminum oxide films with continuously tunable interpore distances

NASA Astrophysics Data System (ADS)

Qin, Xiufang; Zhang, Jinqiong; Meng, Xiaojuan; Deng, Chenhua; Zhang, Lifang; Ding, Guqiao; Zeng, Hao; Xu, Xiaohong

2015-02-01

Nanoporous anodic aluminum oxides are often used as templates for preparation of nanostructures such as nanodot, nanowire and nanotube arrays. The interpore distance of anodic aluminum oxide is the most important parameter in controlling the periodicity of these nanostructures. Herein we demonstrate a simple and yet powerful method to fabricate ordered anodic aluminum oxides with continuously tunable interpore distances. By using mixed solution of citric and oxalic acids with different molar ratio, the range of anodizing voltages within which self-ordered films can be formed were extended to between 40 and 300 V, resulting in the interpore distances change from 100 to 750 nm. Our work realized very broad range of interpore distances in a continuously tunable fashion and the experiment processes are easily controllable and reproducible. The dependence of the interpore distances on acid ratios in mixed solutions was discussed through analysis of anodizing current and it was found that the effective dissociation constant of the mixed acids is of great importance. The interpore distances achieved are comparable to wavelengths ranging from UV to near IR, and may have potential applications in optical meta-materials for photovoltaics and optical sensing.

Binary iron sulfides as anode materials for rechargeable batteries: Crystal structures, syntheses, and electrochemical performance

NASA Astrophysics Data System (ADS)

Xu, Qian-Ting; Li, Jia-Chuang; Xue, Huai-Guo; Guo, Sheng-Ping

2018-03-01

Effective utilization of energy requires the storage and conversion device with high ability. For well-developed lithium ion batteries (LIBs) and highly developing sodium ion batteries (SIBs), this ability especially denotes to high energy and power densities. It's believed that the capacity of a full cell is mainly contributed by anode materials. So, to develop inexpensive anode materials with high capacity are meaningful for various rechargeable batteries' better applications. Iron is a productive element in the crust, and its oxides, sulfides, fluorides, and oxygen acid salts are extensively investigated as electrode materials for batteries. In view of the importance of electrode materials containing iron, this review summarizes the recent achievements on various binary iron sulfides (FeS, FeS2, Fe3S4, and Fe7S8)-type electrodes for batteries. The contents are mainly focused on their crystal structures, synthetic methods, and electrochemical performance. Moreover, the challenges and some improvement strategies are also discussed.

An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode.

PubMed

Gholivand, Mohammad Bagher; Mohammadi-Behzad, Leila

2015-12-01

A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90s at an accumulation potential of 0.75V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05-80 μM and a detection limit (S/N=3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. Copyright © 2015. Published by Elsevier B.V.

High performance novel gadolinium doped ceria/yttria stabilized zirconia/nickel layered and hybrid thin film anodes for application in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Garcia-Garcia, F. J.; Beltrán, A. M.; Yubero, F.; González-Elipe, A. R.; Lambert, R. M.

2017-09-01

Magnetron sputtering under oblique angle deposition was used to produce Ni-containing ultra thin film anodes comprising alternating layers of gadolinium doped ceria (GDC) and yttria stabilized zirconia (YSZ) of either 200 nm or 1000 nm thickness. The evolution of film structure from initial deposition, through calcination and final reduction was examined by XRD, SEM, TEM and TOF-SIMS. After subsequent fuel cell usage, the porous columnar architecture of the two-component layered thin film anodes was maintained and their resistance to delamination from the underlying YSZ electrolyte was superior to that of corresponding single component Ni-YSZ and Ni-GDC thin films. Moreover, the fuel cell performance of the 200 nm layered anodes compared favorably with conventional commercially available thick anodes. The observed dependence of fuel cell performance on individual layer thicknesses prompted study of equivalent but more easily fabricated hybrid anodes consisting of simultaneously deposited Ni-GDC and Ni-YSZ, which procedure resulted in exceptionally intimate mixing and interaction of the components. The hybrids exhibited very unusual and favorable Isbnd V characteristics, along with exceptionally high power densities at high currents. Their discovery is the principal contribution of the present work.

Silver deposition on titanium surface by electrochemical anodizing process reduces bacterial adhesion of Streptococcus sanguinis and Lactobacillus salivarius.

PubMed

Godoy-Gallardo, Maria; Rodríguez-Hernández, Ana G; Delgado, Luis M; Manero, José M; Javier Gil, F; Rodríguez, Daniel

2015-10-01

The aim of this study was to determine the antibacterial properties of silver-doped titanium surfaces prepared with a novel electrochemical anodizing process. Titanium samples were anodized with a pulsed process in a solution of silver nitrate and sodium thiosulphate at room temperature with stirring. Samples were processed with different electrolyte concentrations and treatment cycles to improve silver deposition. Physicochemical properties were determined by X-ray photoelectron spectroscopy, contact angle measurements, white-light interferometry, and scanning electron microscopy. Cellular cytotoxicity in human fibroblasts was studied with lactate dehydrogenase assays. The in vitro effect of treated surfaces on two oral bacteria strains (Streptococcus sanguinis and Lactobacillus salivarius) was studied with viable bacterial adhesion measurements and growth curve assays. Nonparametric statistical Kruskal-Wallis and Mann-Whitney U-tests were used for multiple and paired comparisons, respectively. Post hoc Spearman's correlation tests were calculated to check the dependence between bacteria adhesion and surface properties. X-ray photoelectron spectroscopy results confirmed the presence of silver on treated samples and showed that treatments with higher silver nitrate concentration and more cycles increased the silver deposition on titanium surface. No negative effects in fibroblast cell viability were detected and a significant reduction on bacterial adhesion in vitro was achieved in silver-treated samples compared with control titanium. Silver deposition on titanium with a novel electrochemical anodizing process produced surfaces with significant antibacterial properties in vitro without negative effects on cell viability. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Development and Testing of High Surface Area Iridium Anodes for Molten Oxide Electrolysis

NASA Technical Reports Server (NTRS)

Shchetkovskiy, Anatoliy; McKechnie, Timothy; Sadoway, Donald R.; Paramore, James; Melendez, Orlando; Curreri, Peter A.

2010-01-01

Processing of lunar regolith into oxygen for habitat and propulsion is needed to support future space missions. Direct electrochemical reduction of molten regolith is an attractive method of processing, because no additional chemical reagents are needed. The electrochemical processing of molten oxides requires high surface area, inert anodes. Such electrodes need to be structurally robust at elevated temperatures (1400-1600?C), be resistant to thermal shock, have good electrical conductivity, be resistant to attack by molten oxide (silicate), be electrochemically stable and support high current density. Iridium with its high melting point, good oxidation resistance, superior high temperature strength and ductility is the most promising candidate for anodes in high temperature electrochemical processes. Several innovative concepts for manufacturing such anodes by electrodeposition of iridium from molten salt electrolyte (EL-Form? process) were evaluated. Iridium electrodeposition to form of complex shape components and coating was investigated. Iridium coated graphite, porous iridium structure and solid iridium anodes were fabricated. Testing of electroformed iridium anodes shows no visible degradation. The result of development, manufacturing and testing of high surface, inert iridium anodes will be presented.

Development and Testing of High Surface Area Iridium Anodes for Molten Oxide Electrolysis

NASA Technical Reports Server (NTRS)

Shchetkovskiy, Anatoliy; McKechnie, Timothy; Sadoway, Donald R.; Paramore, James; Melendez, Orlando; Curreri, Peter A.

2010-01-01

Processing of lunar regolith into oxygen for habitat and propulsion is needed to support future space missions. Direct electrochemical reduction of molten regolith is an attractive method of processing, because no additional chemical reagents are needed. The electrochemical processing of molten oxides requires high surface area, inert anodes. Such electrodes need to be structurally robust at elevated temperatures (1400-1600 C), be resistant to thermal shock, have good electrical conductivity, be resistant to attack by molten oxide (silicate), be electrochemically stable and support high current density. Iridium with its high melting point, good oxidation resistance, superior high temperature strength and ductility is the most promising candidate for anodes in high temperature electrochemical processes. Several innovative concepts for manufacturing such anodes by electrodeposition of iridium from molten salt electrolyte (EL-Form process) were evaluated. Iridium electrodeposition to form of complex shape components and coating was investigated. Iridium coated graphite, porous iridium structure and solid iridium anodes were fabricated. Testing of electroformed iridium anodes shows no visible degradation. The result of development, manufacturing and testing of high surface, inert iridium anodes will be presented.

Characteristics from Recycled of Zinc Anode used as a Corrosion Preventing Material on Board Ship

NASA Astrophysics Data System (ADS)

Barokah, B.; Semin, S.; Kaligis, D. D.; Huwae, J.; Fanani, M. Z.; Rompas, P. T. D.

2018-02-01

The objective of this research is to obtain the values of chemical composition, electrochemical potential and electrochemical efficiency. Methods used were experiment with physical tests conducted in metallurgical laboratory and DNV-RP-B401 cathode protection design DNV (Det Norske Veritas) standard. The results showed that the composition of chemical as Zinc (Zn), Aluminium, Cadmium, Plumbumb, Copper and Indium is suitable of standard. The values of electrochemical potential and electrochemical efficiency were respectively. However it can be concluded that the normal meaning of recycled zinc anode with increasing melting temperature can produce zinc anode better than original zinc anode and can be used as cathode protection on board ships. This research can assist in the management of used zinc anode waste, the supply of zinc anodes for consumers at relatively low prices, and recommendations of using zinc anodes for the prevention of corrosion on board ship.

The electrochemical oxide growth behaviour on titanium in acid and alkaline electrolytes.

PubMed

Sul, Y T; Johansson, C B; Jeong, Y; Albrektsson, T

2001-06-01

Titanium implants have a thin oxide surface layer. The properties of this oxide layer may explain the good biocompatibility of titanium implants. Anodic oxidation results in a thickening of the oxide film, with possible improved biocompatability of anodized implants. The aim of the present study was twofold: (1) firstly, to characterize the growth behaviour of galvanostatically prepared anodic oxide films on commercially pure (c.p.) titanium and (2) secondly, to establish a better understanding of the electroche0mical growth behaviour of anodic oxide on commercially pure titanium (ASTM grade 1) after changes of the electrochemical parameters in acetic acid, phosphoric acid, calcium hydroxide, and sodium hydroxide under galvanostatic anodizing mode. The oxide thickness was measured by Ar sputter etching in Auger Electron spectroscopy (AES) and the colours were estimated by an L*a*b* system (lightness, hue and saturation) using a spectrophotometer. In the first part of our study, it was demonstrated that the interference colours were useful to identify the thickness of titanium oxide. It was also found that the anodic forming voltages with slope (dV/dt) in acid electrolytes were higher than in alkaline electrolytes. Each of the used electrolytes demonstrates an intrinsically specific growth constant (nm/V) in the range of 1.4--2.78 nm/V. In the second part of our study we found, as a general trend, that an increase of electrolyte concentration and electrolyte temperature respectively decreases the anodic forming voltage, the anodic forming rate (nm/s) and the current efficiency (nm.cm(2)/C), while an increase of the current density and the surface area ratio of the anode to cathode increase the anodic forming voltage, the anodic forming rate and the current efficiency. The effects of electrolyte concentration, electrolyte temperature, and agitation speed were explained on the basis of the model of the electrical double layer.

Preparation of mesoporous titanium dioxide anode by a film- and pore-forming agent for the dye-sensitized solar cell

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

Hou, Wenjing; Xiao, Yaoming, E-mail: ymxiao@sxu.edu.cn; Han, Gaoyi, E-mail: han_gaoyis@sxu.edu.cn

2016-04-15

Highlights: • PVP is used as a film- and pore-forming agent to prepare the mesoporous TiO{sub 2} anode. • The TiO{sub 2} anode supplies high surface area for the dye adsorption. • The DSSC efficiency is strongly dependent on the pore properties of the TiO{sub 2} anode. • The DSSC efficiency with the TiO{sub 2} anode prepared by 20 wt% PVP reaches 8.39%. - Abstract: A novel mean of generating mesoporous titanium dioxide (TiO{sub 2}) anodes by employing polyvinylpyrrolidone (PVP) as the film- and pore-forming agent are proposed for dye-sensitized solar cells (DSSCs). The influences on the morphology and photovoltaicmore » performances of the TiO{sub 2} anodes are investigated by adjusting the PVP content in synthesizing the mesoporous TiO{sub 2} anodes. The photovoltaic conversion efficiency of the DSSC is found to be strongly dependent on the pore properties of the TiO{sub 2} anode. After the sintering process, the removal of the PVP leaves porously interconnected channel structures inside the TiO{sub 2} anode, supplying enhanced specific surface area for the dye adsorption as well as the efficient electron transmission. As a result, the TiO{sub 2} anode prepared by 20 wt% PVP presents the highest performances, based on which the DSSC achieves the highest conversion efficiency of 8.39%, approximately increased by 56.53% than that of the DSSC fabricated without PVP (5.36%).« less

Investigations of Si Thin Films as Anode of Lithium-Ion Batteries

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

Wu, Qingliu; Shi, Bing; Bareño, Javier

Amorphous silicon thin films having various thicknesses were investigated as a negative electrode material for lithium-ion batteries. Electrochemical characterization of the 20 nm thick thin silicon film revealed a very low first cycle Coulombic efficiency, which can be attributed to the silicon oxide layer formed on both the surface of the as-deposited Si thin film and the interface between the Si and the substrate. Among the investigated films, the 100 nm Si thin film demonstrated the best performance in terms of first cycle efficiency and cycle life. Observations from scanning electron microscopy demonstrated that the generation of cracks was inevitablemore » in the cycled Si thin films, even as the thickness of the film was as little as 20 nm, which was not predicted by previous modeling work. However, the cycling performance of the 20 and 100 nm silicon thin films was not detrimentally affected by these cracks. The poor capacity retention of the 1 mu m silicon thin film was attributed to the delamination.« less

Nanoconfined phosphorus film coating on interconnected carbon nanotubes as ultrastable anodes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Xu, Zhiwei; Zeng, Yan; Wang, Liyuan; Li, Nan; Chen, Cheng; Li, Cuiyu; Li, Jing; Lv, Hanming; Kuang, Liyun; Tian, Xu

2017-07-01

Elemental phosphorus (P) is extensively explored as promising anode candidates due to its abundance, low-cost and high theoretical specific capacity. However, it is of great challenge for P-based materials as practical high-energy-density and long-cycling anodes for its large volume expansion and low conductibility. Here, we significantly improve both cycling and rate performance of red P by cladding the nanoconfined P film on interconnected multi-walled carbon nanotube networks (P-MWCNTs composite) via facile wet ball-milling. The red P-MWCNTs anode presents a superior high reversible capacity of 1396.6 mAh g-1 on the basis of P-MWCNTs composite weight at 50 mA g-1 with capacity retention reaching at ∼90% over 50 cycles. Even at 1000 mA g-1, it still maintains remarkable specific reversible capacity of 934.0 mAh g-1. This markedly enhanced performance is ascribed to synergistic advantages of this unique structure: Intimate contacts between nanosized red P and entangled MWCNTs not only shorten the transmission routes of ions through MWCNTs toward red P, but also motivate the access with electrolyte to open structures of P film. Besides, the confined nanosized P film moderate volume expansions effectively and the entangled MWCNTs networks acted as conductive channels activate high ionic/electronic conductivity of the whole electrodes.

A novel bio-electrochemical system with sand/activated carbon separator, Al anode and bio-anode integrated micro-electrolysis/electro-flocculation cost effectively treated high load wastewater with energy recovery.

PubMed

Gao, Changfei; Liu, Lifen; Yang, Fenglin

2018-02-01

A novel bio-electrochemical system (BES) was developed by integrating micro-electrolysis/electro-flocculation from attaching a sacrificing Al anode to the bio-anode, it effectively treated high load wastewater with energy recovery (maximum power density of 365.1 mW/m 3 and a maximum cell voltage of 0.97 V), and achieving high removals of COD (>99.4%), NH 4 + -N (>98.7%) and TP (>98.6%). The anode chamber contains microbes, activated carbon (AC)/graphite granules and Al anode. It was separated from the cathode chamber containing bifunctional catalytic and filtration membrane cathode (loaded with Fe/Mn/C/F/O catalyst) by a multi-medium chamber (MMC) filled with manganese sand and activated carbon granules, which replaced expensive PEM and reduced cost. An air contact oxidation bed for aeration was still adopted before liquid entering the cathode chamber. micro-electrolysis/electro-flocculation helps in achieving high removal efficiencies and contributes to membrane fouling migration. The increase of activated carbon in the separator MMC increased power generation and reduced system electric resistance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrochemical Deburring

NASA Technical Reports Server (NTRS)

Burley, R. K.

1983-01-01

Electrochemical deburring removes burrs from assembled injector tubes. Since process uses liquid anodic dissolution in liquid electrolyte to proide deburring action, smoothes surfaces and edges in otherwise inaccessible areas. Tool consists of sleeve that contains metallic ring cathode. Sleeve is placed over tube, and electrolytic solution is forced to flow between tube and sleeve. The workpiece serves an anode.

Electrochemical Interpretation of a Stress Corrosion Cracking of Thermally Treated Ni base Alloys in a Lead Contaminated Water

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

Hwang, Seong Sik; Lim, Yun Soo; Kim, Hong Pyo

2007-08-20

Since the PbSCC(Lead stress corrosion cracking) of alloy 600 tubing materials was reported by Copson and Dean in 1965, the effect of lead on a corrosion film and cracking morphology have been continually debated. An electrochemical interaction of lead with the alloying elements of SG tubings was studied and the corrosion products were analyzed. It was found that lead enhanced the anodic dissolution of alloy 600 and alloy 690 in the electrochemical test. The lead preferentially dissolved the Cr from the corrosion film of alloy 600 and alloy 690 in alkaline water. The lead ion seemed to penetrate into themore » TG crack tip and react with the corrosion film. A selective Cr depletion was observed to weaken the stability of the passive film on the alloys. Whereas passivity of Ni became stable in lead containing solution, Cr and Fe passivity became unstable.« less

Structure, Morphology and Optical Properties of TiO2 Films Formed by Anodizing in a Mixed Solution of Citric Acid and Sulfamic Acid

NASA Astrophysics Data System (ADS)

Choudhary, R. K.; Sarkar, P.; Biswas, A.; Mishra, P.; Abraham, G. J.; Sastry, P. U.; Kain, V.

2017-08-01

TiO2 films of 50-180 nm thickness were formed at room temperature by anodization of titanium metal in a mixture of citric acid and sulfamic acid in the potential range of 5-30 V. The films so obtained were characterized for their crystal structure, surface morphology, chemical composition and optical properties. Grazing incidence x-ray diffraction and micro-laser Raman spectroscopy measurements of the anodic films confirmed the formation of brookite phase of TiO2 at anodizing potentials of 15, 20, 25 and 30 V and amorphous structure at 5 and 10 V. Field emission scanning electron microscopy revealed non-porous microstructure of the films. Spectroscopic ellipsometry measurements evaluated the band gap of TiO2 at around 3.3 eV, whereas the refractive index of the films was found to be in the range of 2-2.35, in the visible range of spectrum.

Structural, optical and electrical properties of CeO2 thin films simultaneously prepared by anodic and cathodic electrodeposition

NASA Astrophysics Data System (ADS)

Yang, Yumeng; Du, Xiaoqing; Yi, Chenxi; Liu, Jiao; Zhu, Benfeng; Zhang, Zhao

2018-05-01

CeO2 thin films were deposited on stainless steel (SS) and indium tin oxide (ITO)-coated glass by simultaneous anodic and cathodic electrodeposition, and the influence of negative potential on the formation of ceria films was studied with scanning electron microscopy, X-ray diffraction, Raman spectroscopy, van der Pauw measurements, UV-visible spectroscopy and X-ray photoelectron spectroscopy. The results show that CeO2 films on the anode are slightly affected by the potential, but the particle size, crystal orientation, strain, film thickness, resistivity and Ce(III) content of the films on the cathode increases with increasing potential on the SS substrate. Contradictory to the results of the SS cathode, redshift (Ed changed from 3.95 eV to 3.56 eV and Ei changed from 3.42 eV to 3.04 eV) occurring in the absorption spectrum of CeO2 deposited on the ITO-coated glass cathode indicates that the content of Ce3+ in the cathodic films is dependent on the adopted substrates and decreases as the applied potential is increased.

Polyaniline/Carbon nanotube Electrochromic Films: Electrochemical Polymerization and characterization

NASA Astrophysics Data System (ADS)

Li, Xiao-Xia; Zhao, Liang; Ma, De-Yue; Zeng, Yu-Run

2018-02-01

Polyaniline/Carbon nanotube (PANI/CNT) composite films doped with dodecyl-benzene sulfonic acid were synthesized by cyclic voltammetry on an ITO-coated glass substrate. FTIR, XRD and electrochemical analyzer were used to characterize the micro-morphology, chemical structure, crystallinity and electrochromic behavior of the films, respectively. The effect of CNT content on the properties of the films was investigated. Results show that the introducing CNTs make aniline polymerize easier than before. Within a range, the conductivity and crystallinity of PANI/CNT composites improves with CNT content increasing. The electrochromic device made from the PAN/CNT film with a CNT content of 2.5wt% presents a reflectance contrast of 38.8%, a mean response time of 2.3s and a coloration efficiency of 386.4cm2/C at 540nm. The PAN/CNT film shows better electrochromic behaviors due to some interaction between CNTs and the PANI backbones than PANI film.

Bioelectronic platforms for optimal bio-anode of bio-electrochemical systems: From nano- to macro scopes.

PubMed

Kim, Bongkyu; An, Junyeong; Fapyane, Deby; Chang, In Seop

2015-11-01

The current trend of bio-electrochemical systems is to improve strategies related to their applicability and potential for scaling-up. To date, literature has suggested strategies, but the proposal of correlations between each research field remains insufficient. This review paper provides a correlation based on platform techniques, referred to as bio-electronics platforms (BEPs). These BEPs consist of three platforms divided by scope scale: nano-, micro-, and macro-BEPs. In the nano-BEP, several types of electron transfer mechanisms used by electrochemically active bacteria are discussed. In the micro-BEP, factors affecting the formation of conductive biofilms and transport of electrons in the conductive biofilm are investigated. In the macro-BEP, electrodes and separators in bio-anode are debated in terms of real applications, and a scale-up strategy is discussed. Overall, the challenges of each BEP are highlighted, and potential solutions are suggested. In addition, future research directions are provided and research ideas proposed to develop research interest. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantifying microstructural dynamics and electrochemical activity of graphite and silicon-graphite lithium ion battery anodes

NASA Astrophysics Data System (ADS)

Pietsch, Patrick; Westhoff, Daniel; Feinauer, Julian; Eller, Jens; Marone, Federica; Stampanoni, Marco; Schmidt, Volker; Wood, Vanessa

2016-09-01

Despite numerous studies presenting advances in tomographic imaging and analysis of lithium ion batteries, graphite-based anodes have received little attention. Weak X-ray attenuation of graphite and, as a result, poor contrast between graphite and the other carbon-based components in an electrode pore space renders data analysis challenging. Here we demonstrate operando tomography of weakly attenuating electrodes during electrochemical (de)lithiation. We use propagation-based phase contrast tomography to facilitate the differentiation between weakly attenuating materials and apply digital volume correlation to capture the dynamics of the electrodes during operation. After validating that we can quantify the local electrochemical activity and microstructural changes throughout graphite electrodes, we apply our technique to graphite-silicon composite electrodes. We show that microstructural changes that occur during (de)lithiation of a pure graphite electrode are of the same order of magnitude as spatial inhomogeneities within it, while strain in composite electrodes is locally pronounced and introduces significant microstructural changes.

Corrosion-electrochemical behavior of zirconium in molten alkali metal carbonates

NASA Astrophysics Data System (ADS)

Nikitina, E. V.

2016-08-01

The corrosion and electrochemical characteristics of zirconium during its interaction with molten lithium, sodium, and potassium carbonates containing from 1 to 5 wt % additives to the salt phase are studied in a temperature range of 500-800°C using gravimetry, corrosion potential measurement, and anodic polarization. The substances decreasing the corrosion losses due to the strengthening and thickening of an oxide film (lithium, sodium, potassium hydroxides) are used as passivators. Sodium chloride, fluoride, and sulfate serve as corrosion stimulators (activators).

Analysis of Ag(I) Biocide in Water Samples Using Anodic Stripping Voltammetry with a Boron-Doped Diamond Disk Electrode.

PubMed

Maldonado, Vanessa Y; Espinoza-Montero, Patricio J; Rusinek, Cory A; Swain, Greg M

2018-06-05

The electroanalytical performance of a new commercial boron-doped diamond disk and a traditional nanocrystalline thin-film electrode were compared for the anodic stripping voltammetric determination of Ag(I). The diamond disk electrode is more flexible than the planar film as the former is compatible with most electrochemical cell designs including those incorporating magnetic stirring. Additionally, mechanical polishing and surface cleaning are simpler to execute. Differential pulse anodic stripping voltammetry (DPASV) was used to detect Ag(I) in standard solutions after optimization of the deposition potential, deposition time and scan rate. The optimized conditions were used to determine the concentration of Ag(I) in a NASA simulated potable water sample and a NIST standard reference solution. The electrochemical results were validated by ICP-OES measurements of the same solutions. The detection figures of merit for the disk electrode were as good or superior to those for the thin-film electrode. Detection limits were ≤5 μg L -1 (S/N = 3) for a 120 s deposition period, and response variabilities were <5% RSD. The polished disk electrode presented a more limited linear dynamic range presumably because of the reduced surface area available for metal phase formation. The concentrations of Ag(I) in the two water samples, as determined by DPASV, were in good agreement with the concentrations determined by ICP-OES.

Synthesis and electrochemical characterization of Silicon clathrates as anode materials for Lithium ion batteries

NASA Astrophysics Data System (ADS)

Raghavan, Rahul

Novel materials for Li-ion batteries is one of the principle thrust areas for current research in energy storage, more so than most, considering its widespread use in portable electronic gadgets and plug-in electric and hybrid cars. One of the major limiting factors in a Li-ion battery's energy density is the low specific capacities of the active materials in the electrodes. In the search for high-performance anode materials for Li-ion batteries, many alternatives to carbonaceous materials have been studied. Both cubic and amorphous silicon can reversibly alloy with lithium and have a theoretical capacity of 3500 mAh/g, making silicon a potential high density anode material. However, a large volume expansion of 300% occurs due to changes in the structure during lithium insertion, often leading to pulverization of the silicon. To this end, a class of silicon based cage compounds called clathrates are studied for electrochemical reactivity with lithium. Silicon-clathrates consist of silicon covalently bonded in cage structures comprised of face sharing Si20, Si24 and/or Si28 clusters with guest ions occupying the interstitial positions in the polyhedra. Prior to this, silicon clathrates have been studied primarily for their superconducting and thermoelectric properties. In this work, the synthesis and electrochemical characterization of two categories of silicon clathrates - Type-I silicon clathrate with aluminum framework substitution and barium guest ions (Ba8AlxSi46-x) and Type-II silicon clathrate with sodium guest ions (Nax Si136), are explored. The Type-I clathrate, Ba8AlxSi46-x consists of an open framework of aluminium and silicon, with barium (guest) atoms occupying the interstitial positions. X-ray diffraction studies have shown that a crystalline phase of clathrate is obtained from synthesis, which is powdered to a fine particle size to be used as the anode material in a Li-ion battery. Electrochemical measurements of these type of clathrates have shown

Disordered anodes for Ni-metal rechargeable battery

DOEpatents

Young, Kwo-hsiung; Wang, Lixin; Mays, William C.

2016-11-22

An electrochemical cell is provided that includes a structurally and compositionally disordered electrochemically active alloy material as an anode active material with unexpected capacity against a nickel hydroxide based cathode active material. The disordered metal hydroxide alloy includes three or more transition metal elements and is formed in such a way so as to produce the necessary disorder in the overall system. When an anode active material includes nickel as a predominant, the resulting cells represent the first demonstration of a functional Ni/Ni cell.

Improved Electrochemical Cycling Durability in a Nickel Oxide Double-Layered Film.

PubMed

Hou, Shuai; Zhang, Xiang; Tian, Yanlong; Zhao, Jiupeng; Geng, Hongbin; Qu, Huiying; Zhang, Hangchuan; Zhang, Kun; Wang, Binsheng; Gavrilyuk, Alexander; Li, Yao

2017-11-16

For the first time, a crystalline-amorphous double-layered NiO x film has been prepared by reactive radio frequency magnetron sputtering. This film has exhibited improved electrochemical cycling durability, whereas other electrochromic parameters have been maintained at the required level, namely, a short coloration/bleaching time (0.8 s/1.1 s) and an enhanced transmittance modulation range (62.2 %) at λ=550 nm. Additionally, the double-layered film has shown better reversibility than that of amorphous and crystalline single-layered films. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solvent-induced changes in PEDOT:PSS films for organic electrochemical transistors

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

Zhang, Shiming; Kumar, Prajwal; Nouas, Amel Sarah

2015-01-01

Organic electrochemical transistors based on the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) are of interest for several bioelectronic applications. In this letter, we investigate the changes induced by immersion of PEDOT:PSS films, processed by spin coating from different mixtures, in water and other solvents of different polarities. We found that the film thickness decreases upon immersion in polar solvents, while the electrical conductivity remains unchanged. The decrease in film thickness is minimized via the addition of a cross-linking agent to the mixture used for the spin coating of the films.

Aligned TiO₂ nanotube/nanoparticle heterostructures with enhanced electrochemical performance as three-dimensional anode for lithium-ion microbatteries.

PubMed

Xie, Keyu; Guo, Min; Lu, Wei; Huang, Haitao

2014-11-14

A novel TiO₂ three-dimensional (3D) anode with an aligned TiO₂ nanotube/nanoparticle heterostructure (TiO₂ NTs/NPs) is developed by simply immersing as-anodized TiO₂ NTs into water and further crystallizing the TiO₂ NTs by post-annealing. The heterostructure, with its core in a tubular morphology and with both the outer and inner surface consisting of nanoparticles, is confirmed by FESEM and TEM. A reversible areal capacity of 0.126 mAh · cm(-2) is retained after 50 cycles for the TiO₂ NTs/NPs heterostructure electrode, which is higher than that of the TiO₂ NTs electrode (0.102 mAh · cm(-2) after 50 cycles). At the current densities of 0.02, 0.04, 0.06, 0.08, 0.10 and 0.20 mA · cm(-2), the areal capacities are 0.142, 0.127, 0.117, 0.110, 0.104 and 0.089 mAh · cm(-2), respectively, for the TiO₂ NTs/NPs heterostructure electrode compared to the areal capacities of 0.123, 0.112, 0.105, 0.101, 0.094 and 0.083 mAh · cm(-2), respectively, for the the TiO₂ NTs electrode. The enhanced electrochemical performance is attributed to the unique microstructure of the TiO₂ NTs/NPs heterostructure electrode with the TiO₂ NT core used as a straight pathway for electronic transport and with TiO₂ NP offering enhanced surface areas for facile Li+ insertion/extraction. The results described here inspire a facile approach to fabricate a 3D anode with an enhanced electrochemical performance for lithium-ion microbattery applications.

Electrochemical mineralization and detoxification of naphthenic acids on boron-doped diamond anodes.

PubMed

Diban, Nazely; Urtiaga, Ane

2018-01-05

Electrochemical oxidation (ELOX) with boron-doped diamond (BDD) anodes was successfully applied to degrade a model aqueous solution of a mixture of commercial naphthenic acids (NAs). The model mixture was prepared resembling the NA and salt composition of oil sands process-affected water (OSPW) as described in the literature. The initial concentration of NAs between 70 and 120 mg/L did not influence the electrooxidation kinetics. However, increasing the applied current density from 20 to 100 A/m 2 and the initial chloride concentration from 15 to 70 and 150 mg/L accelerated the rate of NA degradation. At higher chloride concentration, the formation of indirect oxidative species could contribute to the faster oxidation of NAs. Complete chemical oxygen demand removal at an initial NA concentration of 120 mg/L, 70 mg/L of chloride and applied 50 A/m 2 of current density was achieved, and 85% mineralization, defined as the decrease of the total organic carbon (TOC) content, was attained. Moreover, after 6 h of treatment and independently on the experimental conditions, the formation of more toxic species, i.e. perchlorate and organochlorinated compounds, was not detected. Finally, the use of ELOX with BDD anodes produced a 7 to 11-fold reduction of toxicity (IC 50 towards Vibrio fischeri) after 2 h of treatment.

Rechargeable thin film battery and method for making the same

DOEpatents

Goldner, Ronald B.; Liu, Te-Yang; Goldner, Mark A.; Gerouki, Alexandra; Haas, Terry E.

2006-01-03

A rechargeable, stackable, thin film, solid-state lithium electrochemical cell, thin film lithium battery and method for making the same is disclosed. The cell and battery provide for a variety configurations, voltage and current capacities. An innovative low temperature ion beam assisted deposition method for fabricating thin film, solid-state anodes, cathodes and electrolytes is disclosed wherein a source of energetic ions and evaporants combine to form thin film cell components having preferred crystallinity, structure and orientation. The disclosed batteries are particularly useful as power sources for portable electronic devices and electric vehicle applications where high energy density, high reversible charge capacity, high discharge current and long battery lifetimes are required.

Cobalt-Doped Black TiO2 Nanotube Array as a Stable Anode for Oxygen Evolution and Electrochemical Wastewater Treatment.

PubMed

Yang, Yang; Kao, Li Cheng; Liu, Yuanyue; Sun, Ke; Yu, Hongtao; Guo, Jinghua; Liou, Sofia Ya Hsuan; Hoffmann, Michael R

2018-05-04

TiO 2 has long been recognized as a stable and reusable photocatalyst for water splitting and pollution control. However, it is an inefficient anode material in the absence of photoactivation due to its low electron conductivity. To overcome this limitation, a series of conductive TiO 2 nanotube array electrodes have been developed. Even though nanotube arrays are effective for electrochemical oxidation initially, deactivation is often observed within a few hours. To overcome the problem of deactivation, we have synthesized cobalt-doped Black-TiO 2 nanotube array (Co-Black NTA) electrodes that are stable for more than 200 h of continuous operation in a NaClO 4 electrolyte at 10 mA cm -2 . Using X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, electron paramagnetic resonance spectroscopy, and DFT simulations, we are able to show that bulk oxygen vacancies (O v ) are the primary source of the enhanced conductivity of Co-Black. Cobalt doping both creates and stabilizes surficial oxygen vacancies, O v , and thus prevents surface passivation. The Co-Black electrodes outperform dimensionally stable IrO 2 anodes (DSA) in the electrolytic oxidation of organic-rich wastewater. Increasing the loading of Co leads to the formation of a CoO x film on top of Co-Black electrode. The CoO x /Co-Black composite electrode was found to have a lower OER overpotential (352 mV) in comparison to a DSA IrO 2 (434 mV) electrode and a stability that is greater than 200 h in a 1.0 M KOH electrolyte at a current density of 10 mA cm -2 .

Cobalt-Doped Black TiO2 Nanotube Array as a Stable Anode for Oxygen Evolution and Electrochemical Wastewater Treatment

PubMed Central

2018-01-01

TiO2 has long been recognized as a stable and reusable photocatalyst for water splitting and pollution control. However, it is an inefficient anode material in the absence of photoactivation due to its low electron conductivity. To overcome this limitation, a series of conductive TiO2 nanotube array electrodes have been developed. Even though nanotube arrays are effective for electrochemical oxidation initially, deactivation is often observed within a few hours. To overcome the problem of deactivation, we have synthesized cobalt-doped Black-TiO2 nanotube array (Co-Black NTA) electrodes that are stable for more than 200 h of continuous operation in a NaClO4 electrolyte at 10 mA cm–2. Using X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, electron paramagnetic resonance spectroscopy, and DFT simulations, we are able to show that bulk oxygen vacancies (Ov) are the primary source of the enhanced conductivity of Co-Black. Cobalt doping both creates and stabilizes surficial oxygen vacancies, Ov, and thus prevents surface passivation. The Co-Black electrodes outperform dimensionally stable IrO2 anodes (DSA) in the electrolytic oxidation of organic-rich wastewater. Increasing the loading of Co leads to the formation of a CoOx film on top of Co-Black electrode. The CoOx/Co-Black composite electrode was found to have a lower OER overpotential (352 mV) in comparison to a DSA IrO2 (434 mV) electrode and a stability that is greater than 200 h in a 1.0 M KOH electrolyte at a current density of 10 mA cm–2. PMID:29755829

Porous-Nickel-Scaffolded Tin-Antimony Anodes with Enhanced Electrochemical Properties for Li/Na-Ion Batteries.

PubMed

Li, Jiachen; Pu, Jun; Liu, Ziqiang; Wang, Jian; Wu, Wenlu; Zhang, Huigang; Ma, Haixia

2017-08-02

The energy and power densities of rechargeable batteries urgently need to be increased to meet the ever-increasing demands of consumer electronics and electric vehicles. Alloy anodes are among the most promising candidates for next-generation high-capacity battery materials. However, the high capacities of alloy anodes usually suffer from some serious difficulties related to the volume changes of active materials. Porous supports and nanostructured alloy materials have been explored to address these issues. However, these approaches seemingly increase the active material-based properties and actually decrease the electrode-based capacity because of the oversized pores and heavy mass of mechanical supports. In this study, we developed an ultralight porous nickel to scaffold with high-capacity SnSb alloy anodes. The porous-nickel-supported SnSb alloy demonstrates a high specific capacity and good cyclability for both Li-ion and Na-ion batteries. Its capacity retains 580 mA h g -1 at 2 A g -1 after 100 cycles in Li-ion batteries. For a Na-ion battery, the composite electrode can even deliver a capacity of 275 mA h g -1 at 1 A g -1 after 1000 cycles. This study demonstrates that combining the scaffolding function of ultralight porous nickel and the high capacity of the SnSb alloy can significantly enhance the electrochemical performances of Li/Na-ion batteries.

Using Organic Light-Emitting Electrochemical Thin-Film Devices to Teach Materials Science

ERIC Educational Resources Information Center

Sevian, Hannah; Muller, Sean; Rudmann, Hartmut; Rubner, Michael F.

2004-01-01

Materials science can be taught by applying organic light-emitting electrochemical thin-film devices and in this method students were allowed to make a light-emitting device by spin coating a thin film containing ruthenium (II) complex ions onto a glass slide. Through this laboratory method students are provided with the opportunity to learn about…

Power output of microbial fuel cell emphasizing interaction of anodic binder with bacteria

NASA Astrophysics Data System (ADS)

Li, Hongying; Liao, Bo; Xiong, Juan; Zhou, Xingwang; Zhi, Huozhen; Liu, Xiang; Li, Xiaoping; Li, Weishan

2018-03-01

Electrochemically active biofilm is necessary for the electron transfer between bacteria and anodic electrode in microbial fuel cells and selecting the type of anodic electrode material that favours formation of electrochemically active biofilm is crucial for the microbial fuel cell operation. We report a new finding that the interaction of anodic binder with bacteria plays more important role than its hydrophilicity for forming an electrochemically active biofilm, which is emphasized by applying poly(bisphenol A-co-epichorohydrin) as an anodic binder of the microbial fuel cell based on carbon nanotubes as anodic electrode and Escherichia coli as bacterium. The physical characterizations and electrochemical measurements demonstrate that poly(bisphenol A-co-epichorohydrin) exhibits a strong interaction with bacteria and thus provides the microbial fuel cell with excellent power density output. The MFC using poly(bisphenol A-co-epichorohydrin) reaches a maximum power density output of 3.8 W m-2. This value is larger than that of the MFCs using polytetrafluoroethylene that has poorer hydrophilicity, or polyvinyl alcohol that has better hydrophilicity but exhibits weaker interaction with bacteria than poly(bisphenol A-co-epichorohydrin).

Influence of the ZnO nanoarchitecture on the electrochemical performances of binder-free anodes for Li storage

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

Dall'Asta, V.; Tealdi, C.; Resmini, A.

Zinc oxide nanoarchitectures may be employed as binder-free, high specific capacity anodes for lithium batteries. By means of simple and low-impact wet chemistry approaches, we synthesized 1D (nanorods), 2D (single- and multi-layered nanosheets), and 3D (nanobrushes) ZnO arrays. These nanoarchitectures were compared as far as concerns their electrochemical properties and the structural modifications upon lithiation/delithiation. The best results were offered by 2D nanosheets, which showed reversible capacity of the order of 400 mAhg{sup −1} after 100 cycles at 1 Ag{sup −1}. This was due to: i) small nanoparticles, with average diameter of about 10 nm, which maximize the array specificmore » surface area and favor the formation of the LiZn alloy; ii) the presence of a mesoporous texture, which allows larger space for accommodating the volume changes upon lithiation/delithiation. However, also these 2D structures showed large irreversible capacity losses. Our work highlights the need for more efficient buffering solutions in ZnO binder-free nanostructured anodes. - Graphical abstract: ZnO nanosheets as anode materials for lithium batteries.« less

Surface Modifications of Materials by Electrochemical Methods to Improve the Properties for Industrial and Medical Applications

NASA Astrophysics Data System (ADS)

Benea, Lidia

2018-06-01

There are two applied electrochemical methods in our group in order to obtain advanced functional surfaces on materials: (i) direct electrochemical synthesis by electro-codeposition process and (ii) anodization of materials to form nanoporous oxide layers followed by electrodeposition of hydroxyapatite or other bioactive molecules and compounds into porous film. Electrodeposition is a process of low energy consumption, and therefore very convenient for the surface modification of various types of materials. Electrodeposition is a powerful method compared with other methods, which led her to be adopted and spread rapidly in nanotechnology to obtain nanostructured layers and films. Nanoporous thin oxide layers on titanum alloys as support for hydroxyapatite or other biomolecules electrodeposition in view of biomedical applications could be obtained by electrochemical methods. For surface modification of titanium or titanium alloys to improve the biocompatibility or osseointegration, the two steps must be fulfilled; the first is controlled growth of oxide layer followed by second being biomolecule electrodeposition into nanoporous formed titanium oxide layer.

Non-aqueous electrochemical deposition of lead zirconate titanate films for flexible sensor applications

NASA Astrophysics Data System (ADS)

Joseph, Sherin; Kumar, A. V. Ramesh; John, Reji

2017-11-01

Lead zirconate titanate (PZT) is one of the most important piezoelectric materials widely used for underwater sensors. However, PZTs are hard and non-compliant and hence there is an overwhelming attention devoted toward making it flexible by preparing films on flexible substrates by different routes. In this work, the electrochemical deposition of composition controlled PZT films over flexible stainless steel (SS) foil substrates using non-aqueous electrolyte dimethyl sulphoxide (DMSO) was carried out. Effects of various key parameters involved in electrochemical deposition process such as current density and time of deposition were studied. It was found that a current density of 25 mA/cm2 for 5 min gave a good film. The morphology and topography evaluation of the films was carried out by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively, which showed a uniform morphology with a surface roughness of 2 nm. The PZT phase formation was studied using X-ray diffraction (XRD) and corroborated with Raman spectroscopic studies. The dielectric constant, dielectric loss, hysteresis and I-V characteristics of the film was evaluated.

Electrodeposition synthesis and electrochemical properties of nanostructured γ-MnO 2 films

NASA Astrophysics Data System (ADS)

Chou, Shulei; Cheng, Fangyi; Chen, Jun

The thin films of carambola-like γ-MnO 2 nanoflakes with about 20 nm in thickness and at least 200 nm in width were prepared on nickel sheets by combination of potentiostatic and cyclic voltammetric electrodeposition techniques. The as-prepared MnO 2 nanomaterials, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), were used as the active material of the positive electrode for primary alkaline Zn/MnO 2 batteries and electrochemical supercapacitors. Electrochemical measurements showed that the MnO 2 nanoflake films displayed high potential plateau (around 1.0 V versus Zn) in primary Zn/MnO 2 batteries at the discharge current density of 500 mA g -1 and high specific capacitance of 240 F g -1 at the current density of 1 mA cm -2. This indicated the potential application of carambola-like γ-MnO 2 nanoflakes in high-power batteries and electrochemical supercapacitors. The growth process for the one- and three-dimensional nanostructured MnO 2 was discussed on the basis of potentiostatic and cyclic voltammetric techniques. The present synthesis method can be extended to the preparation of other nanostructured metal-oxide films.

Performance comparison of tin oxide anodes to commercially available dimensionally stable anodes.

PubMed

Watts, Richard J; Finn, Dennis D; Wyeth, Megan S; Teel, Amy L

2008-06-01

Dimensionally stable anodes (DSAs) demonstrate potential for the electrochemical treatment of industrial waste streams and disinfection of effluent. Oxidation by laboratory-prepared tin oxide DSAs was compared with that of commercially available ruthenium oxide, iridium oxide, and mixed metal oxide DSAs, using hexanol as a probe molecule. The performance of the four anodes was similar in two-chamber reactors, in which the anode cell was separated from the cathode cell by a Nafion membrane, which allows transmission of current between the chambers, but not passage of chemical constituents. The anodes were then evaluated in single-cell reactors, which are more representative of potential treatment and disinfection applications. However, in the single-cell reactors, the tin oxide anodes were significantly more effective at oxidation and generated higher quality cyclic voltammograms than the other DSAs. These results suggest that tin oxide anodes have greater potential than the three commercially available DSAs tested for industrial waste stream treatment and effluent disinfection.

Development of Thick-Film Thermoelectric Microcoolers Using Electrochemical Deposition

NASA Technical Reports Server (NTRS)

Fleurial, J.-P.; Borshchevsky, A.; Ryan, M. A.; Phillips, W. M.; Snyder, J. G.; Caillat, T.; Kolawa, E. A.; Herman, J. A.; Mueller, P.; Nicolet, M.

2000-01-01

Advanced thermoelectric microdevices integrated into thermal management packages and low power, electrical source systems are of interest for a variety of space and terrestrial applications. By shrinking the size of the thermoelements, or legs, of these devices, it becomes possible to handle much higher heat fluxes, as well as operate at much lower currents and higher voltages that are more compatible with electronic components. The miniaturization of state-of-the-art thermoelectric module technology based on Bi2Te3 alloys is limited due to mechanical and manufacturing constraints for both leg dimensions (100-200 gm thick minimum) and the number of legs (100-200 legs maximum). We are investigating the development of novel microdevices combining high thermal conductivity substrate materials such as diamond, thin film metallization and patterning technology, and electrochemical deposition of thick thermoelectric films. It is anticipated that thermoelectric microcoolers with thousands of thermocouples and capable of pumping more than 200 W/sq cm over a 30 to 60 K temperature difference can be fabricated. In this paper, we report on our progress in developing an electrochemical deposition process for obtaining 10-50 microns thick films of Bi2Te3 and its solid solutions. Results presented here indicate that good quality n-type Bi2Te3, n-type Bi2Te(2.95)Se(0.05) and p-type Bi(0.5)Sb(1.5)Te3 thick films can be deposited by this technique. Some details about the fabrication of the miniature thermoelements are also described.

Laser-Ultrasonic Measurement of Elastic Properties of Anodized Aluminum Coatings

NASA Astrophysics Data System (ADS)

Singer, F.

Anodized aluminum oxide plays a great role in many industrial applications, e.g. in order to achieve greater wear resistance. Since the hardness of the anodized films strongly depends on its processing parameters, it is important to characterize the influence of the processing parameters on the film properties. In this work the elastic material parameters of anodized aluminum were investigated using a laser-based ultrasound system. The anodized films were characterized analyzing the dispersion of Rayleigh waves with a one-layer model. It was shown that anodizing time and temperature strongly influence Rayleigh wave propagation.

A simplified approach to predict performance degradation of a solid oxide fuel cell anode

NASA Astrophysics Data System (ADS)

Khan, Muhammad Zubair; Mehran, Muhammad Taqi; Song, Rak-Hyun; Lee, Jong-Won; Lee, Seung-Bok; Lim, Tak-Hyoung

2018-07-01

The agglomeration of nickel (Ni) particles in a Ni-cermet anode is a significant degradation phenomenon for solid oxide fuel cells (SOFCs). This work aims to predict the performance degradation of SOFCs due to Ni grain growth by using a simplified approach. Accelerated aging of Ni-scandia stabilized zirconia (SSZ) as an SOFC anode is carried out at 900 °C and subsequent microstructural evolution is investigated every 100 h up to 1000 h using scanning electron microscopy (SEM). The resulting morphological changes are quantified using a two-dimensional image analysis technique that yields the particle size, phase proportion, and triple phase boundary (TPB) point distribution. The electrochemical properties of an anode-supported SOFC are characterized using electrochemical impedance spectroscopy (EIS). The changes of particle size and TPB length in the anode as a function of time are in excellent agreement with the power-law coarsening model. This model is further combined with an electrochemical model to predict the changes in the anode polarization resistance. The predicted polarization resistances are in good agreement with the experimentally obtained values. This model for prediction of anode lifetime provides deep insight into the time-dependent Ni agglomeration behavior and its impact on the electrochemical performance degradation of the SOFC anode.

Building one-dimensional oxidenanostructure arrays on conductive metal substrates for lithium-ion battery anodes

NASA Astrophysics Data System (ADS)

Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang

2011-01-01

Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized aluminamembrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.

Fast ion transport at solid-solid interfaces in hybrid battery anodes

NASA Astrophysics Data System (ADS)

Tu, Zhengyuan; Choudhury, Snehashis; Zachman, Michael J.; Wei, Shuya; Zhang, Kaihang; Kourkoutis, Lena F.; Archer, Lynden A.

2018-04-01

Carefully designed solid-electrolyte interphases are required for stable, reversible and efficient electrochemical energy storage in batteries. We report that hybrid battery anodes created by depositing an electrochemically active metal (for example, Sn, In or Si) on a reactive alkali metal electrode by a facile ion-exchange chemistry lead to very high exchange currents and stable long-term performance of electrochemical cells based on Li and Na electrodes. By means of direct visualization and ex situ electrodeposition studies, Sn-Li anodes are shown to be stable at 3 mA cm-2 and 3 mAh cm-2. Prototype full cells in which the hybrid anodes are paired with high-loading LiNi0.8Co0.15Al0.05O2(NCA) cathodes are also reported. As a second demonstration, we create and study Sn-Na hybrid anodes and show that they can be cycled stably for more than 1,700 hours with minimal voltage divergence. Charge storage at the hybrid anodes is reported to involve a combination of alloying and electrodeposition reactions.

Electrochemical delignification of wood pulp using polyoxometalate mediators

Treesearch

R.S. Reiner; E.L. Springer; R.H. Atalla

2003-01-01

It has been found that polyoxometalates (POMs) can act as mediators in the electrochemical oxidation of lignin in pulps. An electrochemical cell, with a Nafion® membrane separating the anode and cathode compartments, was used in the delignification experiments. A softwood kraft pulp was placed in the anode compartment with a buffered 0.01M solution of the...

Patterned titania nanostructures produced by electrochemical anodization of titanium sheet

NASA Astrophysics Data System (ADS)

Dong, Junzhe; Ariyanti, Dessy; Gao, Wei; Niu, Zhenjiang; Weil, Emeline

2017-07-01

A two-step anodization method has been used to produce patterned arrays of TiO2 on the surface of Ti sheet. Hexagonal ripples were created on Ti substrate after removing the TiO2 layer produced by first-step anodization. The shallow concaves were served as an ideal position for the subsequent step anodization due to their low electrical resistance, resulting in novel hierarchical nanostructures with small pits inside the original ripples. The mechanism of morphology evolution during patterned anodization was studied through changing the anodizing voltages and duration time. This work provides a new idea for controlling nanostructures and thus tailoring the photocatalytic property and wettability of anodic TiO2.

[Isolation and identification of electrochemically active microorganism from micro-aerobic environment].

PubMed

Wu, Song; Xiao, Yong; Zheng, Zhi-Yong; Zheng, Yue; Yang, Zhao-Hui; Zhao, Feng

2014-10-01

Extracellular electron transfer of electrochemically active microorganism plays vital role in biogeochemical cycling of metals and carbon and in biosynthesis of bioenergy. Compared to anaerobic anode, micro-aerobic anode captures more energy from microbial fuel cell. However, most of previous researches focused on functioning bacteria in anaerobic anode, functioning bacteria in micro-aerobic anode was rarely studied. Herein, we used the traditional aerobic screening technology to isolate functioning bacteria from a micro-aerobic anode. Three pure cultures Aeromonas sp. WS-XY2, Citrobacter sp. WS-XY3 and Bacterium strain WS-XY4 were obtained. WS-XY2 and WS-XY3 were belonged to Proteobacteria, whereas WS-XY4 was possibly a new species. Cyclic voltammetry and chronoamperometry analysis demonstrated all of them showed the electrochemical activity by direct extracellular electron transfer, and micro-aerobic anode could select bacteria that have similar electrochemical activity to proliferate on the anode. We further conclude that functioning bacteria in micro-aerobic anode are more efficient than that of anaerobic anode may be the reason that micro-aerobic anode has better performance than anaerobic anode. Therefore, a thorough study of functioning bacteria in micro-aerobic anode will significantly promote the energy recovery from microbial fuel cell.

Method of making an electrolyte for an electrochemical cell

DOEpatents

Bates, J.B.; Dudney, N.J.

1996-04-30

Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode. Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between {minus}15 C and 150 C. 9 figs.

Method of making an electrolyte for an electrochemical cell

DOEpatents

Bates, John B.; Dudney, Nancy J.

1996-01-01

Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes.

PubMed

Economou, Anastasios; Voulgaropoulos, Anastasios

2003-01-01

The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV.

LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes

PubMed Central

Economou, Anastasios; Voulgaropoulos, Anastasios

2003-01-01

The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV. PMID:18924623

Preliminary Electrochemical Characterization of Anode Supported Solid Oxide Cell (AS-SOC) Produced in the Institute of Power Engineering Operated in Electrolysis Mode (SOEC)

NASA Astrophysics Data System (ADS)

Kupecki, Jakub; Motyliński, Konrad; Skrzypkiewicz, Marek; Wierzbicki, Michał; Naumovich, Yevgeniy

2017-12-01

The article discusses the operation of solid oxide electrochemical cells (SOC) developed in the Institute of Power Engineering as prospective key components of power-to-gas systems. The fundamentals of the solid oxide cells operated as fuel cells (SOFC - solid oxide fuel cells) and electrolysers (SOEC - solid oxide fuel cells) are given. The experimental technique used for electrochemical characterization of cells is presented. The results obtained for planar cell with anodic support are given and discussed. Based on the results, the applicability of the cells in power-to-gas systems (P2G) is evaluated.

Electrochemical deposition of layered copper thin films based on the diffusion limited aggregation

PubMed Central

Wei, Chenhuinan; Wu, Guoxing; Yang, Sanjun; Liu, Qiming

2016-01-01

In this work layered copper films with smooth surface were successfully fabricated onto ITO substrate by electrochemical deposition (ECD) and the thickness of the films was nearly 60 nm. The resulting films were characterized by SEM, TEM, AFM, XPS, and XRD. We have investigated the effects of potential and the concentration of additives and found that 2D dendritic-like growth process leaded the formation of films. A suitable growth mechanism based on diffusion limited aggregation (DLA) mechanism for the copper films formation is presented, which are meaningful for further designing homogeneous and functional films. PMID:27734900

Surface modifications for carbon lithium intercalation anodes

DOEpatents

Tran, Tri D.; Kinoshita, Kimio

2000-01-01

A prefabricated carbon anode containing predetermined amounts of passivating film components is assembled into a lithium-ion rechargeable battery. The modified carbon anode enhances the reduction of the irreversible capacity loss during the first discharge of a cathode-loaded cell. The passivating film components, such as Li.sub.2 O and Li.sub.2 CO.sub.3, of a predetermined amount effective for optimal passivation of carbon, are incorporated into carbon anode materials to produce dry anodes that are essentially free of battery electrolyte prior to battery assembly.

Controllable Electrochemical Synthesis of Copper Sulfides as Sodium-Ion Battery Anodes with Superior Rate Capability and Ultralong Cycle Life.

PubMed

Li, Haomiao; Wang, Kangli; Cheng, Shijie; Jiang, Kai

2018-03-07

Sodium-ion batteries (SIBs) are prospective alternative to lithium-ion batteries for large-scale energy-storage applications, owing to the abundant resources of sodium. Metal sulfides are deemed to be promising anode materials for SIBs due to their low-cost and eco-friendliness. Herein, for the first time, series of copper sulfides (Cu 2 S, Cu 7 S 4 , and Cu 7 KS 4 ) are controllably synthesized via a facile electrochemical route in KCl-NaCl-Na 2 S molten salts. The as-prepared Cu 2 S with micron-sized flakes structure is first investigated as anode of SIBs, which delivers a capacity of 430 mAh g -1 with a high initial Coulombic efficiency of 84.9% at a current density of 100 mA g -1 . Moreover, the Cu 2 S anode demonstrates superior capability (337 mAh g -1 at 20 A g -1 , corresponding to 50 C) and ultralong cycle performance (88.2% of capacity retention after 5000 cycles at 5 A g -1 , corresponding to 0.0024% of fade rate per cycle). Meanwhile, the pseudocapacitance contribution and robust porous structure in situ formed during cycling endow the Cu 2 S anodes with outstanding rate capability and enhanced cyclic performance, which are revealed by kinetics analysis and ex situ characterization.

Nonlinear dielectric thin films for high-power electric storage with energy density comparable with electrochemical supercapacitors.

PubMed

Yao, Kui; Chen, Shuting; Rahimabady, Mojtaba; Mirshekarloo, Meysam Sharifzadeh; Yu, Shuhui; Tay, Francis Eng Hock; Sritharan, Thirumany; Lu, Li

2011-09-01

Although batteries possess high energy storage density, their output power is limited by the slow movement of charge carriers, and thus capacitors are often required to deliver high power output. Dielectric capacitors have high power density with fast discharge rate, but their energy density is typically much lower than electrochemical supercapacitors. Increasing the energy density of dielectric materials is highly desired to extend their applications in many emerging power system applications. In this paper, we review the mechanisms and major characteristics of electric energy storage with electrochemical supercapacitors and dielectric capacitors. Three types of in-house-produced ferroic nonlinear dielectric thin film materials with high energy density are described, including (Pb(0.97)La(0.02))(Zr(0.90)Sn(0.05)Ti(0.05))O(3) (PLZST) antiferroelectric ceramic thin films, Pb(Zn(1/3)Nb(2/3))O(3-)Pb(Mg(1/3)Nb(2/3))O(3-)PbTiO(3) (PZN-PMN-PT) relaxor ferroelectric ceramic thin films, and poly(vinylidene fluoride) (PVDF)-based polymer blend thin films. The results showed that these thin film materials are promising for electric storage with outstandingly high power density and fairly high energy density, comparable with electrochemical supercapacitors.

Self-healing of cracks formed in Silicon-Aluminum anodes electrochemically cycled at high lithiation rates

NASA Astrophysics Data System (ADS)

Bhattacharya, Sandeep; Alpas, Ahmet T.

2016-10-01

Lithiation-induced volume changes in Si result in fracture and fragmentation of Si anodes in Li-ion batteries. This paper reports the self-healing behaviour of cracks observed in micron-sized Si particles dispersed in a ductile Al matrix of a Si-Al electrode electrochemically cycled vs. Li/Li+ using a high lithiation rate of 15.6 C. Cross-sectional high-resolution transmission electron microscopy and Raman spectroscopy revealed that an amorphous layer with a depth up to ∼100 nm was formed at the surface of Si particles. In-situ optical microscopy performed during electrochemical experiments revealed development of cracks in Si particles as the voltage decreased to 0.02 V during lithiation. Self-healing of cracks in Si particles occurred in two steps: i) arresting of the crack growth at the Si/Al interface as the surrounding Al matrix had a higher fracture toughness and thus acted as a barrier to crack propagation, and ii) closure of cracks due to compressive stresses applied to the crack faces by the amorphous zones formed on each side of the crack paths.

Facile synthesis of hollow Sn-Co@PMMA nanospheres as high performance anodes for lithium-ion batteries via galvanic replacement reaction and in situ polymerization

NASA Astrophysics Data System (ADS)

Yu, Xiaohui; Jiang, Anni; Yang, Hongyan; Meng, Haowen; Dou, Peng; Ma, Daqian; Xu, Xinhua

2015-08-01

Polymethyl methacrylate (PMMA)-coated hollow Sn-Co nanospheres (Sn-Co@PMMA) with superior electrochemical performance had been synthesized via a facile galvanic replacement method followed by an in situ emulsion polymerization route. The properties were investigated in detail and results show that the hollow Sn-Co nanospheres were evenly coated with PMMA. Benefiting from the protection of the PMMA layers, the hollow Sn-Co@PMMA nanocomposite is capable of retaining a high capacity of 590 mAh g-1 after 100 cycles with a coulomb efficiency above 98%, revealing better electrochemical properties compared with hollow Sn-Co anodes. The PMMA coating could help accommodate the mechanical strain caused by volume expansion and stabilize the solid electrolyte interphase (SEI) film formed on the electrode. Such a facile process could be further extended to other anode materials for lithium-ion batteries.

Comparative studies on single-layer reduced graphene oxide films obtained by electrochemical reduction and hydrazine vapor reduction

NASA Astrophysics Data System (ADS)

Wang, Zhijuan; Wu, Shixin; Zhang, Juan; Chen, Peng; Yang, Guocheng; Zhou, Xiaozhu; Zhang, Qichun; Yan, Qingyu; Zhang, Hua

2012-02-01

The comparison between two kinds of single-layer reduced graphene oxide (rGO) sheets, obtained by reduction of graphene oxide (GO) with the electrochemical method and hydrazine vapor reduction, referred to as E-rGO and C-rGO, respectively, is systematically studied. Although there is no morphology difference between the E-rGO and C-rGO films adsorbed on solid substrates observed by AFM, the reduction process to obtain the E-rGO and C-rGO films is quite different. In the hydrazine vapor reduction, the nitrogen element is incorporated into the obtained C-rGO film, while no additional element is introduced to the E-rGO film during the electrochemical reduction. Moreover, Raman spectra show that the electrochemical method is more effective than the hydrazine vapor reduction method to reduce the GO films. In addition, E-rGO shows better electrocatalysis towards dopamine than does C-rGO. This study is helpful for researchers to understand these two different reduction methods and choose a suitable one to reduce GO based on their experimental requirements.

A Step toward High-Energy Silicon-Based Thin Film Lithium Ion Batteries.

PubMed

Reyes Jiménez, Antonia; Klöpsch, Richard; Wagner, Ralf; Rodehorst, Uta C; Kolek, Martin; Nölle, Roman; Winter, Martin; Placke, Tobias

2017-05-23

The next generation of lithium ion batteries (LIBs) with increased energy density for large-scale applications, such as electric mobility, and also for small electronic devices, such as microbatteries and on-chip batteries, requires advanced electrode active materials with enhanced specific and volumetric capacities. In this regard, silicon as anode material has attracted much attention due to its high specific capacity. However, the enormous volume changes during lithiation/delithiation are still a main obstacle avoiding the broad commercial use of Si-based electrodes. In this work, Si-based thin film electrodes, prepared by magnetron sputtering, are studied. Herein, we present a sophisticated surface design and electrode structure modification by amorphous carbon layers to increase the mechanical integrity and, thus, the electrochemical performance. Therefore, the influence of amorphous C thin film layers, either deposited on top (C/Si) or incorporated between the amorphous Si thin film layers (Si/C/Si), was characterized according to their physical and electrochemical properties. The thin film electrodes were thoroughly studied by means of electrochemical impedance spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. We can show that the silicon thin film electrodes with an amorphous C layer showed a remarkably improved electrochemical performance in terms of capacity retention and Coulombic efficiency. The C layer is able to mitigate the mechanical stress during lithiation of the Si thin film by buffering the volume changes and to reduce the loss of active lithium during solid electrolyte interphase formation and cycling.

Interfacial chemistry of zinc anodes for reinforced concrete structures

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

Covino, B.S. Jr.; Bullard, S.J.; Cramer, S.D.

1997-12-01

Thermally-sprayed zinc anodes are used in both galvanic and impressed current cathodic protection systems for reinforced concrete structures. The Albany Research Center, in collaboration with the Oregon Department of Transportation, has been studying the effect of electrochemical aging on the bond strength of zinc anodes for bridge cathodic protection systems. Changes in anode bond strength and other anode properties can be explained by the chemistry of the zinc-concrete interface. The chemistry of the zinc-concrete interface in laboratory electrochemical aging studies is compared with that of several bridges with thermal-sprayed zinc anodes and which have been in service for 5 tomore » 10 years using both galvanic and impressed current cathodic protection systems. The bridges are the Cape Creek Bridge on the Oregon coast and the East Camino Undercrossing near Placerville, CA. Also reported are interfacial chemistry results for galvanized steel rebar from the 48 year old Longbird Bridge in Bermuda.« less

Electrochemical mineralization of perfluorocarboxylic acids (PFCAs) by ce-doped modified porous nanocrystalline PbO2 film electrode.

PubMed

Niu, Junfeng; Lin, Hui; Xu, Jiale; Wu, Hao; Li, Yangyang

2012-09-18

The Ce-doped modified porous nanocrystalline PbO(2) film electrode prepared by electrodeposition technology was used for electrochemical mineralization of environmentally persistent perfluorinated carboxylic acids (PFCAs) (~C(4)-C(8)), i.e., perfluorobutanoic acid (PFBA), perfluopentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoheptanoic acid (PFHpA), and perfluorooctanoic acid (PFOA) in aqueous solution (100 mL of 100 mg L(-1)). The degradation of PFCAs follows pseudo-first-order kinetics, and the values of the relative rate constant (k) depend upon chain length k(PFHpA) (4.1 × 10(-2) min(-1); corresponding half-life 16.8 min) ≈ 1.1k(PFOA) ≈ 2.5k(PFHxA)≈ 6.9k(PFPeA) ≈ 9.7k(PFBA). The carbon mineralization indices [i.e., 1 - (TOC(insolution)/TOC(inPFCA,degraded))] were 0.49, 0.70, 0.84, 0.91, and 0.95 for PFBA, PFPeA, PFHxA, PFHpA, and PFOA, respectively, after 90 min electrolysis. The major mineralization product, F(-), as well as low amount of intermediate PFCAs with shortened chain lengths were detected in aqueous solution. By observing the intermediates and tracking the concentration change, a possible pathway of electrochemical mineralization is proposed as follows: Kolbe decarboxylation reaction occurs first at the anode to form the perfluoroalkyl radical, followed by reaction with hydroxyl radicals to form the perfluoroalkyl alcohol which then undergoes intramolecular rearrangement to form the perfluoroalkyl fluoride. After this, the perfluoroalkyl fluoride reforms perfluorinated carboxylic with shorter chain length than its origin by hydrolysis. This electrochemical technique could be employed to treat PFCAs (~C(4)-C(8)) in contaminated wastewater.

Freestanding NiFe Oxyfluoride Holey Film with Ultrahigh Volumetric Capacitance for Flexible Asymmetric Supercapacitors.

PubMed

Liang, Kun; Marcus, Kyle; Yang, Zhenzhong; Zhou, Le; Pan, Hao; Bai, Yuanli; Du, Yingge; Engelhard, Mark H; Yang, Yang

2018-01-01

In this work, a freestanding NiFe oxyfluoride (NiFeOF) holey film is prepared by electrochemical deposition and anodic treatments. With the combination of good electrical conductivity and holey structure, the NiFeOF holey film offers superior electrochemical performance with maximum specific capacitance of 670 F cm -3 (134 mF cm -2 ), due to the following reasons: (i) The residual metal alloy framework can be used as the current collector to improve electrode conductivity. Moreover, the as-prepared freestanding NiFeOF holey film can be used as a supercapacitor electrode without reliance on binders and other additives. The residual metal alloy framework and binder-free electrode effectively reduce electrode resistance, thus improving electron transport. (ii) The highly interconnected holey structure and hierarchical pore distribution provide a high specific surface area to improve electron transport, enhancing rapid ion transport, and mitigating diffusion limitations throughout the holey film. (iii) The excellent mechanical characteristics facilitate flexibility and cyclability related performance. Additionally, the NiFeOF holey film presents exceptional electrochemical performance, showing that it is a promising alternative for small/microsize electronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical properties of magnetron sputtered WO{sub 3} thin films

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

Madhavi, V.; Kondaiah, P.; Hussain, O. M.

2013-02-05

Thin films of tungsten oxide (WO{sub 3}) were deposited on ITO substrates by using RF magnetron sputtering at oxygen and argon atmospheres of 6 Multiplication-Sign 10{sup -2}Pa and 4 Pa respectively. The chemical composition and surface morphology of the WO{sub 3} thin films have been studied by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) respectively. The results indicate that the deposited WO{sub 3} thin films are nearly stoichiometric. The electrochemical performances of the WO{sub 3} thin films have been evaluated by galvonostatic charging/discharging method. The discharge capacity was 15{mu}Ah/cm{sup 2}{mu}m at the initial cycle and faded rapidly inmore » the first few cycles and stabilized at a lesser stage.« less

Electrochemical Atomic Layer Epitaxy of Thin Film CdSe

NASA Astrophysics Data System (ADS)

Pham, L.; Kaleida, K.; Happek, U.; Mathe, M. K.; Vaidyanathan, R.; Stickney, J. L.; Radevic, M.

2002-10-01

Electrochemical atomic layer epitaxy (EC-ALE) is a current developmental technique for the fabrication of compound semiconductor thin films. The deposition of elements making up the compound utilizes surface limited reactions where the potential is less than that required for bulk growth. This growth method offers mono-atomic layer control, allowing the deposition of superlattices with sharp interfaces. Here we report on the EC-ALE formation of CdSe thin films on Au and Cu substrates using an automated flow cell system. The band gap was measured using IR absorption and photoconductivity and found to be consistent with the literature value of 1.74 eV at 300K and 1.85 eV at 20K. The stoichiometry of the thin film was confirmed with electron microprobe analysis and x-ray diffraction.

Ternary CNTs@TiO₂/CoO Nanotube Composites: Improved Anode Materials for High Performance Lithium Ion Batteries.

PubMed

Madian, Mahmoud; Ummethala, Raghunandan; Naga, Ahmed Osama Abo El; Ismail, Nahla; Rümmeli, Mark Hermann; Eychmüller, Alexander; Giebeler, Lars

2017-06-20

TiO₂ nanotubes (NTs) synthesized by electrochemical anodization are discussed as very promising anodes for lithium ion batteries, owing to their high structural stability, high surface area, safety, and low production cost. However, their poor electronic conductivity and low Li⁺ ion diffusivity are the main drawbacks that prevent them from achieving high electrochemical performance. Herein, we report the fabrication of a novel ternary carbon nanotubes (CNTs)@TiO₂/CoO nanotubes composite by a two-step synthesis method. The preparation includes an initial anodic fabrication of well-ordered TiO₂/CoO NTs from a Ti-Co alloy, followed by growing of CNTs horizontally on the top of the oxide films using a simple spray pyrolysis technique. The unique 1D structure of such a hybrid nanostructure with the inclusion of CNTs demonstrates significantly enhanced areal capacity and rate performances compared to pure TiO₂ and TiO₂/CoO NTs, without CNTs tested under identical conditions. The findings reveal that CNTs provide a highly conductive network that improves Li⁺ ion diffusivity, promoting a strongly favored lithium insertion into the TiO₂/CoO NT framework, and hence resulting in high capacity and an extremely reproducible high rate capability.

Fabrication of a novel aluminum surface covered by numerous high-aspect-ratio anodic alumina nanofibers

NASA Astrophysics Data System (ADS)

Nakajima, Daiki; Kikuchi, Tatsuya; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

2015-11-01

The formation behavior of anodic alumina nanofibers via anodizing in a concentrated pyrophosphoric acid under various conditions was investigated using electrochemical measurements and SEM/TEM observations. Pyrophosphoric acid anodizing at 293 K resulted in the formation of numerous anodic alumina nanofibers on an aluminum substrate through a thin barrier oxide and honeycomb oxide with narrow walls. However, long-term anodizing led to the chemical dissolution of the alumina nanofibers. The density of the anodic alumina nanofibers decreased as the applied voltage increased in the 10-75 V range. However, active electrochemical dissolution of the aluminum substrate occurred at a higher voltage of 90 V. Low temperature anodizing at 273 K resulted in the formation of long alumina nanofibers measuring several micrometers in length, even though a long processing time was required due to the low current density during the low temperature anodizing. In contrast, high temperature anodizing easily resulted in the formation and chemical dissolution of alumina nanofibers. The structural nanofeatures of the anodic alumina nanofibers were controlled by choosing of the appropriate electrochemical conditions, and numerous high-aspect-ratio alumina nanofibers (>100) can be successfully fabricated. The anodic alumina nanofibers consisted of a pure amorphous aluminum oxide without anions from the employed electrolyte.

Building one-dimensional oxide nanostructure arrays on conductive metal substrates for lithium-ion battery anodes.

PubMed

Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang

2011-01-01

Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized alumina membrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.

Ohmic resistance in a multi-anode MxCs

EPA Pesticide Factsheets

A-3txf_sequence summary.xksx: Abundance of contigs or unique sequences for each biofilm samples from anodes in the MEC reactorHodon Waterloo final_fasta_working.docx: Raw sequences with their identification numbersRNA S1_MEC.docx: Representative sequences with their ID number and taxonomyThis dataset is associated with the following publication:Santodomingo, J., H. Ryu, B. Dhar, and H. Lee. Ohmic resistance affects microbial community and electrochemical kinetics in a multi-anode microbial electrochemical cell. JOURNAL OF POWER SOURCES. Elsevier Science Ltd, New York, NY, USA, 331: 315-321, (2016).

Comparative electrochemical analysis of crystalline and amorphous anodized iron oxide nanotube layers as negative electrode for LIB.

PubMed

Pervez, Syed Atif; Kim, Doohun; Farooq, Umer; Yaqub, Adnan; Choi, Jung-Hee; Lee, You-Jin; Doh, Chil-Hoon

2014-07-23

This work is a comparative study of the electrochemical performance of crystalline and amorphous anodic iron oxide nanotube layers. These nanotube layers were grown directly on top of an iron current collector with a vertical orientation via a simple one-step synthesis. The crystalline structures were obtained by heat treating the as-prepared (amorphous) iron oxide nanotube layers in ambient air environment. A detailed morphological and compositional characterization of the resultant materials was performed via transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Raman spectroscopy. The XRD patterns were further analyzed using Rietveld refinements to gain in-depth information on their quantitative phase and crystal structures after heat treatment. The results demonstrated that the crystalline iron oxide nanotube layers exhibit better electrochemical properties than the amorphous iron oxide nanotube layers when evaluated in terms of the areal capacity, rate capability, and cycling performance. Such an improved electrochemical response was attributed to the morphology and three-dimensional framework of the crystalline nanotube layers offering short, multidirectional transport lengths, which favor rapid Li(+) ions diffusivity and electron transport.

Novel structure formation at the bottom surface of porous anodic alumina fabricated by single step anodization process.

PubMed

Ali, Ghafar; Ahmad, Maqsood; Akhter, Javed Iqbal; Maqbool, Muhammad; Cho, Sung Oh

2010-08-01

A simple approach for the growth of long-range highly ordered nanoporous anodic alumina film in H(2)SO(4) electrolyte through a single step anodization without any additional pre-anodizing procedure is reported. Free-standing porous anodic alumina film of 180 microm thickness with through hole morphology was obtained. A simple and single step process was used for the detachment of alumina from aluminum substrate. The effect of anodizing conditions, such as anodizing voltage and time on the pore diameter and pore ordering is discussed. The metal/oxide and oxide/electrolyte interfaces were examined by high resolution scanning transmission electron microscope. The arrangement of pores on metal/oxide interface was well ordered with smaller diameters than that of the oxide/electrolyte interface. The inter-pore distance was larger in metal/oxide interface as compared to the oxide/electrolyte interface. The size of the ordered domain was found to depend strongly upon anodizing voltage and time. (c) 2010 Elsevier Ltd. All rights reserved.

Controlling the anodizing conditions in preparation of an nanoporous anodic aluminium oxide template

NASA Astrophysics Data System (ADS)

Nazemi, Azadeh; Abolfazl, Seyed; Sadjadi, Seyed

2014-12-01

Porous anodic aluminium oxide (AAO) template is commonly used in the synthesis of one-dimensional nanostructures, such as nanowires and nanorods, due to its simple fabrication process. Controlling the anodizing conditions is important because of their direct influence on the size of AAO template pores; it affects the size of nanostructures that are fabricated in AAO template. In present study, several alumina templates were fabricated by a two-step electrochemical anodization in different conditions, such as the time of first process, its voltage, and electrolyte concentration. The effect of these factors on pore diameters of AAO templates was investigated using scanning electron microscopy (SEM).

Antibacterial activity of microstructured sacrificial anode thin films by combination of silver with platinum group elements (platinum, palladium, iridium).

PubMed

Köller, Manfred; Bellova, Petri; Javid, Siyamak Memar; Motemani, Yahya; Khare, Chinmay; Sengstock, Christina; Tschulik, Kristina; Schildhauer, Thomas A; Ludwig, Alfred

2017-05-01

Five different Ag dots arrays (16 to 400dots/mm 2 ) were fabricated on a continuous platinum, palladium, or iridium thin film and for comparison also on titanium film by sputter deposition and photolithographic patterning. To analyze the antibacterial activity of these microstructured films Staphylococcus aureus (S. aureus) were placed onto the array surfaces and cultivated overnight. To analyze the viability of planktonic as well as surface adherent bacteria, the applied bacterial fluid was subsequently aspirated, plated on blood agar plates and adherent bacteria were detected by fluorescence microscopy. A particular antibacterial effect towards S. aureus was induced by Ag dot arrays on each of the platinum group thin film (sacrificial anode system for Ag) in contrast to Ag dot arrays fabricated on the Ti thin films (non-sacrificial anode system for Ag). Among platinum group elements the Ir-Ag system exerted the highest antibacterial activity which was accompanied by most advanced dissolution of the Ag dots and Ag ion release compared to Ag dots on Pt or Pd. Copyright © 2016 Elsevier B.V. All rights reserved.

Effective Infiltration of Gel Polymer Electrolyte into Silicon-Coated Vertically Aligned Carbon Nanofibers as Anodes for Solid-State Lithium-Ion Batteries.

PubMed

Pandey, Gaind P; Klankowski, Steven A; Li, Yonghui; Sun, Xiuzhi Susan; Wu, Judy; Rojeski, Ronald A; Li, Jun

2015-09-23

This study demonstrates the full infiltration of gel polymer electrolyte into silicon-coated vertically aligned carbon nanofibers (Si-VACNFs), a high-capacity 3D nanostructured anode, and the electrochemical characterization of its properties as an effective electrolyte/separator for future all-solid-state lithium-ion batteries. Two fabrication methods have been employed to form a stable interface between the gel polymer electrolyte and the Si-VACNF anode. In the first method, the drop-casted gel polymer electrolyte is able to fully infiltrate into the open space between the vertically aligned core-shell nanofibers and encapsulate/stabilize each individual nanofiber in the polymer matrix. The 3D nanostructured Si-VACNF anode shows a very high capacity of 3450 mAh g(-1) at C/10.5 (or 0.36 A g(-1)) rate and 1732 mAh g(-1) at 1C (or 3.8 A g(-1)) rate. In the second method, a preformed gel electrolyte film is sandwiched between an Si-VACNF electrode and a Li foil to form a half-cell. Most of the vertical core-shell nanofibers of the Si-VACNF anode are able to penetrate into the gel polymer film while retaining their structural integrity. The slightly lower capacity of 2800 mAh g(-1) at C/11 rate and ∼1070 mAh g(-1) at C/1.5 (or 2.6 A g(-1)) rate have been obtained, with almost no capacity fade for up to 100 cycles. Electrochemical impedance spectroscopy does not show noticeable changes after 110 cycles, further revealing the stable interface between the gel polymer electrolyte and the Si-VACNFs anode. These results show that the infiltrated flexible gel polymer electrolyte can effectively accommodate the stress/strain of the Si shell due to the large volume expansion/contraction during the charge-discharge processes, which is particularly useful for developing future flexible solid-state lithium-ion batteries incorporating Si-anodes.

Electrochemical Partial Reforming of Ethanol into Ethyl Acetate Using Ultrathin Co3O4 Nanosheets as a Highly Selective Anode Catalyst

PubMed Central

2016-01-01

Electrochemical partial reforming of organics provides an alternative strategy to produce valuable organic compounds while generating H2 under mild conditions. In this work, highly selective electrochemical reforming of ethanol into ethyl acetate is successfully achieved by using ultrathin Co3O4 nanosheets with exposed (111) facets as an anode catalyst. Those nanosheets were synthesized by a one-pot, templateless hydrothermal method with the use of ammonia. NH3 was demonstrated critical to the overall formation of ultrathin Co3O4 nanosheets. With abundant active sites on Co3O4 (111), the as-synthesized ultrathin Co3O4 nanosheets exhibited enhanced electrocatalytic activities toward water and ethanol oxidations in alkaline media. More importantly, over the Co3O4 nanosheets, the electrooxidation from ethanol to ethyl acetate was so selective that no other oxidation products were yielded. With such a high selectivity, an electrolyzer cell using Co3O4 nanosheets as the anode electrocatalyst and Ni–Mo nanopowders as the cathode electrocatalyst has been successfully built for ethanol reforming. The electrolyzer cell was readily driven by a 1.5 V battery to achieve the effective production of both H2 and ethyl acetate. After the bulk electrolysis, about 95% of ethanol was electrochemically reformed into ethyl acetate. This work opens up new opportunities in designing a material system for building unique devices to generate both hydrogen and high-value organics at room temperature by utilizing electric energy from renewable sources. PMID:27610415

Electrochemical Partial Reforming of Ethanol into Ethyl Acetate Using Ultrathin Co3O4 Nanosheets as a Highly Selective Anode Catalyst.

PubMed

Dai, Lei; Qin, Qing; Zhao, Xiaojing; Xu, Chaofa; Hu, Chengyi; Mo, Shiguang; Wang, Yu Olivia; Lin, Shuichao; Tang, Zichao; Zheng, Nanfeng

2016-08-24

Electrochemical partial reforming of organics provides an alternative strategy to produce valuable organic compounds while generating H2 under mild conditions. In this work, highly selective electrochemical reforming of ethanol into ethyl acetate is successfully achieved by using ultrathin Co3O4 nanosheets with exposed (111) facets as an anode catalyst. Those nanosheets were synthesized by a one-pot, templateless hydrothermal method with the use of ammonia. NH3 was demonstrated critical to the overall formation of ultrathin Co3O4 nanosheets. With abundant active sites on Co3O4 (111), the as-synthesized ultrathin Co3O4 nanosheets exhibited enhanced electrocatalytic activities toward water and ethanol oxidations in alkaline media. More importantly, over the Co3O4 nanosheets, the electrooxidation from ethanol to ethyl acetate was so selective that no other oxidation products were yielded. With such a high selectivity, an electrolyzer cell using Co3O4 nanosheets as the anode electrocatalyst and Ni-Mo nanopowders as the cathode electrocatalyst has been successfully built for ethanol reforming. The electrolyzer cell was readily driven by a 1.5 V battery to achieve the effective production of both H2 and ethyl acetate. After the bulk electrolysis, about 95% of ethanol was electrochemically reformed into ethyl acetate. This work opens up new opportunities in designing a material system for building unique devices to generate both hydrogen and high-value organics at room temperature by utilizing electric energy from renewable sources.

Real space mapping of Li-ion transport in amorphous Si anodes with nanometer resolution.

PubMed

Balke, Nina; Jesse, Stephen; Kim, Yoongu; Adamczyk, Leslie; Tselev, Alexander; Ivanov, Ilia N; Dudney, Nancy J; Kalinin, Sergei V

2010-09-08

The electrical bias driven Li-ion motion in silicon anode materials in thin film battery heterostructures is investigated using electrochemical strain microscopy (ESM), which is a newly developed scanning probe microscopy based characterization method. ESM utilizes the intrinsic link between bias-controlled Li-ion concentration and molar volume of electrode materials, providing the capability for studies on the sub-20 nm scale, and allows the relationship between Li-ion flow and microstructure to be established. The evolution of Li-ion transport during the battery charging is directly observed.

Cadmium sulfide nanocluster-based electrochemical stripping detection of DNA hybridization.

PubMed

Zhu, Ningning; Zhang, Aiping; He, Pingang; Fang, Yuzhi

2003-03-01

A novel, sensitive electrochemical DNA hybridization detection assay, using cadmium sulfide (CdS) nanoclusters as the oligonucleotide labeling tag, is described. The assay relies on the hybridization of the target DNA with the CdS nanocluster oligonucleotide DNA probe, followed by the dissolution of the CdS nanoclusters anchored on the hybrids and the indirect determination of the dissolved cadmium ions by sensitive anodic stripping voltammetry (ASV) at a mercury-coated glassy carbon electrode (GCE). The results showed that only a complementary sequence could form a double-stranded dsDNA-CdS with the DNA probe and give an obvious electrochemical response. A three-base mismatch sequence and non-complementary sequence had negligible response. The combination of the large number of cadmium ions released from each dsDNA hybrid with the remarkable sensitivity of the electrochemical stripping analysis for cadmium at mercury-film GCE allows detection at levels as low as 0.2 pmol L(-1) of the complementary sequence of DNA.

Overcoming the Instability of Nanoparticle-Based Catalyst Films in Alkaline Electrolyzers by using Self-Assembling and Self-Healing Films.

PubMed

Barwe, Stefan; Masa, Justus; Andronescu, Corina; Mei, Bastian; Schuhmann, Wolfgang; Ventosa, Edgar

2017-07-10

Engineering stable electrodes using highly active catalyst nanopowders for electrochemical water splitting remains a challenge. We report an innovative and general approach for attaining highly stable catalyst films with self-healing capability based on the in situ self-assembly of catalyst particles during electrolysis. The catalyst particles are added to the electrolyte forming a suspension that is pumped through the electrolyzer. Particles with negatively charged surfaces stick onto the anode, while particles with positively charged surfaces stick to the cathode. The self-assembled catalyst films have self-healing properties as long as sufficient catalyst particles are present in the electrolyte. The proof-of-concept was demonstrated in a non-zero gap alkaline electrolyzer using NiFe-LDH and Ni x B catalyst nanopowders for anode and cathode, respectively. Steady cell voltages were maintained for at least three weeks during continuous electrolysis at 50-100 mA cm -2 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

In situ electrochemical and photo-electrochemical generation of the fenton reagent: a potentially important new water treatment technology.

PubMed

Peralta-Hernández, J M; Meas-Vong, Yunny; Rodríguez, Francisco J; Chapman, Thomas W; Maldonado, Manuel I; Godínez, Luis A

2006-05-01

In this work, the design and construction of an annular tube reactor for the electrochemical and photo-electrochemical in situ generation of H2O2 are described. By cathodic reduction of dissolved oxygen and the coupled oxidation of water at a UV-illuminated nanocrystalline-TiO2 semiconductor anode, it was found that the electrochemically generated H2O2 can be employed to readily oxidize the model compound Direct Yellow-52 in dilute acidic solution at high rates in the presence of small quantities of dissolved iron(II). Although, the model organic compound is chemically stable under UV radiation, its electrochemical oxidation rate increases substantially when the semiconductor anode is illuminated as compared to the same processes carried out in the dark.

Anodic Dissolution of Al Current Collectors in Unconventional Solvents for High Voltage Electrochemical Double-Layer Capacitors.

PubMed

Krummacher, Jakob; Heß, Lars-Henning; Balducci, Andrea

2017-09-04

This study investigated the anodic dissolution of Al current collectors in unconventional electrolytes for high voltage electrochemical double-layer capacitors (EDLCs) containing adiponitrile (ADN), 3-cyanopropionic acid methyl ester (CPAME), 2-methyl-glutaronitrile (2-MGN) as solvent, and tetraethylammonium tetrafluoroborate (Et 4 NBF 4 ) and tetraethylammonium bis(trifluoromethanesulfonyl)imide (Et 4 NTFSI) as conductive salts. To have a comparison with the state-of-the-art electrolytes, the same salts were also used in combination with acetonitrile (ACN). The chemical-physical properties of the electrolytes were investigated. Furthermore, their impact on the anodic dissolution of Al was analyzed in detail as well as the influence of this process on the performance of high voltage EDLCs. The results of this study indicated that in the case of Et 4 NBF 4 -based electrolytes, the use of an alternative solvent is very beneficial for the realization of stable devices. When Et 4 NTFSI is used, the reduced solubility of the complex Al(TFSI) 3 appears to be the key for the realization of advanced electrolytes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microbial Activity Influences Electrical Conductivity of Biofilm Anode

EPA Science Inventory

This study assessed the conductivity of a Geobacter-enriched biofilm anode along with biofilm activity in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH ...

Electrochemical power-producing cell. [Li/Se

DOEpatents

Cairns, E.J.; Chilenskas, A.A.; Steunenberg, R.K.; Shimotake, H.

1972-05-30

An electrochemical power-producing cell including a molten lithium metal anode, a molten selenium metal cathode, a paste electrolyte separating the anode from the cathode, an anode current collector, and a single layer of niobium expanded metal formed in corrugated shape as cathode current collector is described. In addition, means are provided for sealing the anode and the cathode from loss of lithium and selenium, respectively, and an insulator is provided between the anode housing and the paste electrolyte disk.

Sequential electrochemical treatment of dairy wastewater using aluminum and DSA-type anodes.

PubMed

Borbón, Brenda; Oropeza-Guzman, Mercedes Teresita; Brillas, Enric; Sirés, Ignasi

2014-01-01

Dairy wastewater is characterized by a high content of hardly biodegradable dissolved, colloidal, and suspended organic matter. This work firstly investigates the performance of two individual electrochemical treatments, namely electrocoagulation (EC) and electro-oxidation (EO), in order to finally assess the mineralization ability of a sequential EC/EO process. EC with an Al anode was employed as a primary pretreatment for the conditioning of 800 mL of wastewater. A complete reduction of turbidity, as well as 90 and 81% of chemical oxygen demand (COD) and total organic carbon (TOC) removal, respectively, were achieved after 120 min of EC at 9.09 mA cm(-2). For EO, two kinds of dimensionally stable anodes (DSA) electrodes (Ti/IrO₂-Ta₂O₅ and Ti/IrO₂-SnO₂-Sb₂O₅) were prepared by the Pechini method, obtaining homogeneous coatings with uniform composition and high roughness. The (·)OH formed at the DSA surface from H₂O oxidation were not detected by electron spin resonance. However, their indirect determination by means of H₂O₂ measurements revealed that Ti/IrO₂-SnO₂-Sb₂O₅ is able to produce partially physisorbed radicals. Since the characterization of the wastewater revealed the presence of indole derivatives, preliminary bulk electrolyses were done in ultrapure water containing 1 mM indole in sulfate and/or chloride media. The performance of EO with the Ti/IrO₂-Ta₂O₅ anode was evaluated from the TOC removal and the UV/Vis absorbance decay. The mineralization was very poor in 0.05 M Na₂SO₄, whereas it increased considerably at a greater Cl(-) content, meaning that the oxidation mediated by electrogenerated species such as Cl₂, HClO, and/or ClO(-) competes and even predominates over the (·)OH-mediated oxidation. The EO treatment of EC-pretreated dairy wastewater allowed obtaining a global 98 % TOC removal, decreasing from 1,062 to <30 mg L(-1).

Surface enhanced Raman scattering of biospecies on anodized aluminum oxide films

NASA Astrophysics Data System (ADS)

Zhang, C.; Smirnov, A. I.; Hahn, D.; Grebel, H.

2007-06-01

Traditionally, aluminum and anodized aluminum oxide films (AAO) are not the platforms of choice for surface-enhanced raman scattering (SERS) experiments despite of the aluminum's large negative permittivity value. Here we examine the usefulness of aluminum and nanoporous alumina platforms for detecting soft biospecies ranging from bacterial spores to protein markers. We used these flat platforms to examine SERS of a model protein (cytochrome c from bovine heart tissue) and bacterial cells (spores of Bacillus subtilis ATCC13933 used as Anthrax simulant) and demonstrated clear Raman amplification.

The electrochemical behavior of poly 1-pyrenemethyl methacrylate binder and its effect on the interfacial chemistry of a silicon electrode

NASA Astrophysics Data System (ADS)

Haregewoin, Atetegeb Meazah; Terborg, Lydia; Zhang, Liang; Jurng, Sunhyung; Lucht, Brett L.; Guo, Jinghua; Ross, Philip N.; Kostecki, Robert

2018-02-01

The physico-chemical properties of poly (1-pyrenemethyl methacrylate) (PPy) are presented with respect to its use as a binder in a Si composite anode for Li-ion batteries. PPy thin-films on Si(100) wafer and Cu model electrodes are shown to exhibit superior adhesion as compared to conventional polyvinylidene difluoride (PVdF) binder. Electrochemical testing of the model bi-layer PPy/Si(100) electrodes in a standard organic carbonate electrolyte reveal higher electrolyte reduction current and an overall irreversible cathodic charge consumption during initial cycling versus the uncoated Si electrode. The PPy thin-film is also shown to impede lithiation of the underlying Si. XAS, AFM, TGA and ATR-FTIR analysis indicated that PPy binder is both chemically and electrochemically stable in the cycling potential range however significant swelling is observed due to a selective uptake of diethyl carbonate (DEC) from the electrolyte. The increased concentration of DEC and depletion of ethylene carbonate (EC) at the Si/PPy interface leads to continuous decomposition of the electrolyte and results in non-passivating behavior of the Si(100)/PPy electrode as compared to pristine silicon. Consequently, PPy binder improves the mechanical integrity of composite Si anodes but it influences mass transport at the Si(100)/PPy interface and alters electrochemical response of silicon during cycling in an adverse manner.

Ternary CNTs@TiO2/CoO Nanotube Composites: Improved Anode Materials for High Performance Lithium Ion Batteries

PubMed Central

Madian, Mahmoud; Ummethala, Raghunandan; Abo El Naga, Ahmed Osama; Ismail, Nahla; Rümmeli, Mark Hermann; Eychmüller, Alexander; Giebeler, Lars

2017-01-01

TiO2 nanotubes (NTs) synthesized by electrochemical anodization are discussed as very promising anodes for lithium ion batteries, owing to their high structural stability, high surface area, safety, and low production cost. However, their poor electronic conductivity and low Li+ ion diffusivity are the main drawbacks that prevent them from achieving high electrochemical performance. Herein, we report the fabrication of a novel ternary carbon nanotubes (CNTs)@TiO2/CoO nanotubes composite by a two-step synthesis method. The preparation includes an initial anodic fabrication of well-ordered TiO2/CoO NTs from a Ti-Co alloy, followed by growing of CNTs horizontally on the top of the oxide films using a simple spray pyrolysis technique. The unique 1D structure of such a hybrid nanostructure with the inclusion of CNTs demonstrates significantly enhanced areal capacity and rate performances compared to pure TiO2 and TiO2/CoO NTs, without CNTs tested under identical conditions. The findings reveal that CNTs provide a highly conductive network that improves Li+ ion diffusivity, promoting a strongly favored lithium insertion into the TiO2/CoO NT framework, and hence resulting in high capacity and an extremely reproducible high rate capability. PMID:28773032

Sandwiched Thin-Film Anode of Chemically Bonded Black Phosphorus/Graphene Hybrid for Lithium-Ion Battery.

PubMed

Liu, Hanwen; Zou, Yuqin; Tao, Li; Ma, Zhaoling; Liu, Dongdong; Zhou, Peng; Liu, Hongbo; Wang, Shuangyin

2017-09-01

A facile vacuum filtration method is applied for the first time to construct sandwich-structure anode. Two layers of graphene stacks sandwich a composite of black phosphorus (BP), which not only protect BP from quickly degenerating but also serve as current collector instead of copper foil. The BP composite, reduced graphene oxide coated on BP via chemical bonding, is simply synthesized by solvothermal reaction at 140 °C. The sandwiched film anode used for lithium-ion battery exhibits reversible capacities of 1401 mAh g -1 during the 200th cycle at current density of 100 mA g -1 indicating superior cycle performance. Besides, this facile vacuum filtration method may also be available for other anode material with well dispersion in N-methyl pyrrolidone (NMP). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of patterned single-crystal SrTiO3 thin films by ion slicing and anodic bonding

NASA Astrophysics Data System (ADS)

Lee, Yoo Seung; Djukic, Djordje; Roth, Ryan M.; Laibowitz, Robert; Izuhara, Tomoyuki; Osgood, Richard M.; Bakhru, Sasha; Bakhru, Hassaram; Si, Weidong; Welch, David

2006-09-01

A new technique for directly fabricating patterned thin films (<1μm thick) of fully single-crystal strontium titanate uses deep H+ implantation into the oxide sample, followed by anodic bonding of the sample to a Pyrex or Pyrex-on-Si substrate. The dielectric properties and crystal structure of such thin films are characterized and are found to be essentially those of the bulk single crystal.

The Development of Non-Enzymatic Glucose Biosensors Based on Electrochemically Prepared Polypyrrole-Chitosan-Titanium Dioxide Nanocomposite Films.

PubMed

Al-Mokaram, Ali M A Abdul Amir; Yahya, Rosiyah; Abdi, Mahnaz M; Mahmud, Habibun Nabi Muhammad Ekramul

2017-05-31

The performance of a modified electrode of nanocomposite films consisting of polypyrrole-chitosan-titanium dioxide (Ppy-CS-TiO₂) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO₂ nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO₂ NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO₂ in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1-14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO₂ nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell.

Accommodating lithium into 3D current collectors with a submicron skeleton towards long-life lithium metal anodes

PubMed Central

Yang, Chun-Peng; Yin, Ya-Xia; Zhang, Shuai-Feng; Li, Nian-Wu; Guo, Yu-Guo

2015-01-01

Lithium metal is one of the most attractive anode materials for electrochemical energy storage. However, the growth of Li dendrites during electrochemical deposition, which leads to a low Coulombic efficiency and safety concerns, has long hindered the application of rechargeable Li-metal batteries. Here we show that a 3D current collector with a submicron skeleton and high electroactive surface area can significantly improve the electrochemical deposition behaviour of Li. Li anode is accommodated in the 3D structure without uncontrollable Li dendrites. With the growth of Li dendrites being effectively suppressed, the Li anode in the 3D current collector can run for 600 h without short circuit and exhibits low voltage hysteresis. The exceptional electrochemical performance of the Li-metal anode in the 3D current collector highlights the importance of rational design of current collectors and reveals a new avenue for developing Li anodes with a long lifespan. PMID:26299379

The effect of crystal orientation on the aluminum anodes of the aluminum-air batteries in alkaline electrolytes

NASA Astrophysics Data System (ADS)

Fan, Liang; Lu, Huimin; Leng, Jing; Sun, Zegao; Chen, Chunbo

2015-12-01

Recently, aluminum-air (Al-air) batteries have received attention from researchers as an exciting option for safe and efficient batteries. The electrochemical performance of Aluminum anode remains an active area of investigation. In this paper, the electrochemical properties of polycrystalline Al, Al (001), (110) and (111) single crystals are investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 4 M NaOH and KOH. Hydrogen corrosion rates of the Al anodes are determined by hydrogen collection. Battery performance using the anodes is tested by constant current discharge at 10 mA cm-2. This is the first report showing that the electrochemical properties of Al are closely related to the crystallographic orientation in alkaline electrolytes. The (001) crystallographic plane has good corrosion resistance but (110) is more sensitive. Al (001) single crystals display higher anode efficiency and capacity density. Controlling the crystallographic orientation of the Al anode is another way to improve the performance of Al-air batteries in alkaline electrolytes.

Facile synthesis and photo electrochemical performance of SnSe thin films