Sample records for oxyiodides
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Strongly Enhanced Photovoltaic Performance and Defect Physics of Air-Stable Bismuth Oxyiodide (BiOI)
Hoye, Robert L. Z.; Lee, Lana C.; Kurchin, Rachel C.; ...
2017-07-17
Bismuth-based compounds have recently gained increasing attention as potentially nontoxic and defect-tolerant solar absorbers. However, many of the new materials recently investigated show limited photovoltaic performance. Herein, one such compound is explored in detail through theory and experiment: bismuth oxyiodide (BiOI). BiOI thin films are grown by chemical vapor transport and found to maintain the same tetragonal phase in ambient air for at least 197 d. The computations suggest BiOI to be tolerant to antisite and vacancy defects. All-inorganic solar cells (ITO|NiO x|BiOI|ZnO|Al) with negligible hysteresis and up to 80% external quantum efficiency under select monochromatic excitation are demonstrated. Themore » short-circuit current densities and power conversion efficiencies under AM 1.5G illumination are nearly double those of previously reported BiOI solar cells, as well as other bismuth halide and chalcohalide photovoltaics recently explored by many groups. Through a detailed loss analysis using optical characterization, photoemission spectroscopy, and device modeling, direction for future improvements in efficiency is provided. In conclusion, this work demonstrates that BiOI, previously considered to be a poor photocatalyst, is promising for photovoltaics.« less
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Hoye, Robert L Z; Lee, Lana C; Kurchin, Rachel C; Huq, Tahmida N; Zhang, Kelvin H L; Sponseller, Melany; Nienhaus, Lea; Brandt, Riley E; Jean, Joel; Polizzotti, James Alexander; Kursumović, Ahmed; Bawendi, Moungi G; Bulović, Vladimir; Stevanović, Vladan; Buonassisi, Tonio; MacManus-Driscoll, Judith L
2017-09-01
Bismuth-based compounds have recently gained increasing attention as potentially nontoxic and defect-tolerant solar absorbers. However, many of the new materials recently investigated show limited photovoltaic performance. Herein, one such compound is explored in detail through theory and experiment: bismuth oxyiodide (BiOI). BiOI thin films are grown by chemical vapor transport and found to maintain the same tetragonal phase in ambient air for at least 197 d. The computations suggest BiOI to be tolerant to antisite and vacancy defects. All-inorganic solar cells (ITO|NiO x |BiOI|ZnO|Al) with negligible hysteresis and up to 80% external quantum efficiency under select monochromatic excitation are demonstrated. The short-circuit current densities and power conversion efficiencies under AM 1.5G illumination are nearly double those of previously reported BiOI solar cells, as well as other bismuth halide and chalcohalide photovoltaics recently explored by many groups. Through a detailed loss analysis using optical characterization, photoemission spectroscopy, and device modeling, direction for future improvements in efficiency is provided. This work demonstrates that BiOI, previously considered to be a poor photocatalyst, is promising for photovoltaics. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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NASA Astrophysics Data System (ADS)
Vinoth, R.; Babu, S. Ganesh; Ramachandran, R.; Neppolian, B.
2017-10-01
Herein, Bismuth oxyiodide (BiOI) - reduced graphene oxide (rGO) photocatalysts were prepared via simple hydrothermal method. The BiOI-rGO photocatalyst exhibited high crystallinity with tetragonal phase of BiOI. In addition, the electronic interaction between rGO sheet and BiOI reduced the band-gap value from 1.86 eV of bare BiOI to 1.51 eV of BiOI-rGO (6 wt%) photocatalyst. More interestingly, the rGO showed a strong influence on tailoring the morphology of BiOI to different nanostructures with different rGO loading (wt%), which further reflected differences in the photocatalytic activity. A significant quenching in the photoluminescence intensity of rGO supported BiOI photocatalyst confirmed the effective suppression of electron-hole pair recombination. The optimized rGO (4 wt%) loaded BiOI photocatalyst significantly improved the photocatalytic activity (∼85%) towards the degradation of methyl orange (MO) dye compared to that of pristine BiOI (∼29%). Thus, around three folds enhancement in the photocatalytic activity of BiOI-rGO (4 wt%) catalyst was mainly attributed to ultrafast separation of electron-hole pairs and rapid transportation of carriers by rGO support. The superior photocatalytic activity demonstrated by this newly synthesized BiOI-rGO photocatalyst makes it's a potential candidate for environmental remediation process.
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Hou, Jianhua; Wei, Rui; Wu, Xiaoge; Tahir, Muhammad; Wang, Xiaozhi; Butt, Faheem K; Cao, Chuanbao
2018-05-15
Efficient photocatalysts induced by visible light (e.g. BiOI) have attracted wide attention for energy storage and environmental pollutant rehabilitation. In this work, N-doped bamboo tube-like carbon (NTC) was derived directly from the carbonization of bio-waste (withered typha grass) under an ammonia atmosphere. During fabrication, the BiOI/NTC material was used as a self-sacrificing template and I- ions were gradually replaced by OH- ions from NH3·H2O solution. Then Bi7O9I3/NTC was formed with micro-/nanohierarchical structures, which could exactly be explained by the in situ ion exchange-recrystallization mechanism. Thereinto, the well-defined hierarchical lantern-like Bi7O9I3 composed of interconnecting ultrathin nanosheets firmly embedded the "bamboo tubes" of NTC, which endow sufficient interface and high specific surface area (40 m2 g-1). The multiple synergistic effects of the lantern-like structure with ultrathin nanosheets, low iodine content and well-contacted interface endow the synthesized Bi7O9I3/NTC with outstanding visible-light catalytic activity. The results show that the obtained Bi7O9I3/NTC degraded 93.5% of methyl orange and 97.6% of rhodamine B within 2 hours, showing superior performance as compared to the pure BiOI. Therefore, our work demonstrates a controllable approach that can provide guidelines for designing optimized bismuth oxyiodide-based photocatalyst materials and has the potential for application in environmental remediation.
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NASA Astrophysics Data System (ADS)
Ma, Haipeng; Zhang, Jing; Liu, Zhifeng
2017-11-01
The novel WO3 nanorods (NRs)/BiOI core/shell structure composite is used as an efficient photoanode applied in photoelectrochemical (PEC) water splitting for the first time. It is synthesized via facile hydrothermal method and, successive ionic layer adsorption and reaction (SILAR) process. This facile synthesis route can achieve uniform WO3/BiOI core/shell composite nanostructures and obtain varied BiOI morphologies simultaneously. The WO3 NRs/BiOI-20 composite exhibits enhanced PEC activity compared to pristine WO3 with a photocurrent density of 0.79 mA cm-2 measured at 0.8 V vs. RHE under AM 1.5G. This excellent performance benefits from the broader absorption spectrum and suppressed electron-hole recombination. This novel core/shell composite may provide insight in developing more efficient solar driven photoelectrodes.
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Hahn, Nathan T; Hoang, Son; Self, Jeffrey L; Mullins, C Buddie
2012-09-25
Bismuth oxy-iodide is a potentially interesting visible-light-active photocatalyst; yet there is little research regarding its photoelectrochemical properties. Herein we report the synthesis of BiOI nanoplatelet photoelectrodes by spray pyrolysis on fluorine-doped tin oxide substrates at various temperatures. The films exhibited n-type conductivity, most likely due to the presence of anion vacancies, and optimized films possessed incident photon conversion efficiencies of over 20% in the visible range for the oxidation of I(-) to I(3)(-) at 0.4 V vs Ag/AgCl in acetonitrile. Visible-light photons (λ > 420 nm) contributed approximately 75% of the overall photocurrent under AM1.5G illumination, illustrating their usefulness under solar light illumination. A deposition temperature of 260 °C was found to result in the best performance due to the balance of morphology, crystallinity, impurity levels, and optical absorption, leading to photocurrents of roughly 0.9 mA/cm(2) at 0.4 V vs Ag/AgCl. Although the films performed stably in acetonitrile, their performance decreased significantly upon extended exposure to water, which was apparently caused by a loss of surface iodine and subsequent formation of an insulating bismuth hydroxide layer.
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Visible-Light-Driven BiOI-Based Janus Micromotor in Pure Water.
Dong, Renfeng; Hu, Yan; Wu, Yefei; Gao, Wei; Ren, Biye; Wang, Qinglong; Cai, Yuepeng
2017-02-08
Light-driven synthetic micro-/nanomotors have attracted considerable attention due to their potential applications and unique performances such as remote motion control and adjustable velocity. Utilizing harmless and renewable visible light to supply energy for micro-/nanomotors in water represents a great challenge. In view of the outstanding photocatalytic performance of bismuth oxyiodide (BiOI), visible-light-driven BiOI-based Janus micromotors have been developed, which can be activated by a broad spectrum of light, including blue and green light. Such BiOI-based Janus micromotors can be propelled by photocatalytic reactions in pure water under environmentally friendly visible light without the addition of any other chemical fuels. The remote control of photocatalytic propulsion by modulating the power of visible light is characterized by velocity and mean-square displacement analysis of optical video recordings. In addition, the self-electrophoresis mechanism has been confirmed for such visible-light-driven BiOI-based Janus micromotors by demonstrating the effects of various coated layers (e.g., Al 2 O 3 , Pt, and Au) on the velocity of motors. The successful demonstration of visible-light-driven Janus micromotors holds a great promise for future biomedical and environmental applications.
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NASA Astrophysics Data System (ADS)
Marchelek, Martyna; Grabowska, Ewelina; Klimczuk, Tomasz; Lisowski, Wojciech; Giamello, Elio; Zaleska-Medynska, Adriana
2018-03-01
A series of novel BiyXz-TiO2/SrTiO3 composites were prepared by multistep synthesis route. The as-prepared photocatalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FT-IR), Raman spectra and BET analysis. The photocatalytic activity test was performed in aqueous solution of phenol under the irradiation of visible light range (λ ≥ 420 nm). Obtained results revealed that the BiOI_TiO2/SrTiO3 sample exhibit the highest photocatalytic activity under visible irradiation (0.6 μmol/dm3/min). Thus, it was demonstrated that modification of the TiO2/SrTiO3 microspheres by flowers-like structure made of bismuth oxyiodide resulted in enhancement of photocatalytic activity under visible light. The role of active species during the decomposition process of organic compound was investigated using different types of active species scavengers as well as electron paramagnetic resonance analysis (EPR). The study showed that in the BiOI_TiO2/SrTiO3/Vis system the holes (h+) plays relevant role in phenol decomposition. Furthermore, the stability and recyclable properties of obtained BiOI_TiO2/SrTiO3 sample were confirmed during three consecutive processes.
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Wang, Yanhu; Zhang, Lina; Cui, Kang; Xu, Caixia; Li, Hao; Liu, Hong; Yu, Jinghua
2018-02-15
One solar-driven electrochromic photoelectrochemical fuel cell (PFC) with highly efficient energy conversion and storage is easily constructed to achieve quantitative self-powered sensing. Layered bismuth oxyiodide-zinc oxide nanorod arrays (ZnO@BiOI NRA) with a core/shell p-n heterostructure are fabricated as the photoanode with electrochromic Prussian blue (PB) as the cathode. The core/shell p-n heterostructure for the ZnO@BiOI photoanode can effectively boost the photoelectrochemical (PEC) performance through the improvement of photon absorption and charge carrier separation. The optimal assembled PFC yields an open-circuit voltage (V OC ) of 0.48 V with the maximum power output density (P max ) as high as 155 μW cm -2 upon illumination. Benefitting from the interactive color-changing behavior of PB, the cathode not only exhibits cathodic catalytic activity in the PFC but also serves as an electrochromic display for self-powered sensing. The as-constructed PFC possesses multiple readable signal output nanochannels through the maximum power output density (P max ) of the PFC or the color change of PB. Meanwhile, the dual-signal-output makes the as-constructed self-powered sensor highly available in various operations demands with the enhanced reliability. With the advantages of high efficiency of PFCs, unique assay ability, and broad environmental suitability, the constructed self-powered platform shows broad application prospects as an integrated smart analytical device.
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NASA Astrophysics Data System (ADS)
Kandanapitiye, Murthi S.
The combination of nanotechnology with medicinal chemistry has developed into a burgeoning research area. Nanomaterials (NMs) could be seamlessly interfaced with various facets in biology, biochemistry, medicinal chemistry and environmental chemistry that may not be available to the same material in the bulk scale. This dissertation research has focused on the development of nanoparticulate coordination polymers for diagnostic and therapeutic applications. Modern imaging techniques include X-ray computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT) and positron emission tomography (PET). We have successfully developed several types of nanoparticulate diagnostics and therapeutics that have some potential usefulness in biomedicine. Synthesis and characterization of nanoparticulate based PET (Positron emission tomography)/SPECT (Single photon emission computed tomography) are discussed in chapter 3. In chapter 4, preparation and potential utility of non-gadolinium based MRI contrast agent are reported for T1-weighted application. As far as the solely effectiveness of relaxation is concerned, Gd-based T 1-weighted MRI contrast agents have excellent enhancement of image contrast but they have risks of biological toxicity. Consequently, the search for T 1-weighted CAs with high efficacy and low toxicity has gained attention toward the Mn(II) and Fe(III). Fe(III) is considered to be more toxic to cells because free ferric or ferrous ions can catalyze the production of reactive oxygen species via the Fenton reactions. Paramagnetic chelates of Mn(II) could be employed as T1-weighted CAs. However, it is challenging to design and synthesize highly stable Mn(II) complexes that could maintain the integrity when administered to living system. Chapter 4 describes the synthesis and utility of nanoparticulate Mn analogue of Prussian blue (K2Mn 3[FeII(CN)6]2) as an effective T1 MRI contrast agent for cellular imaging X-ray computed tomography is capable of delineating the 3-D images of soft tissues with superb quality. The variation of X-ray attenuation from one tissue to another is used to generate the well spatial resolved superb quality images. Exogenous radiopaque agents are necessary for the superb visualization of different types of soft tissues. Heavy metals with high atomic number are better suited for biomedical applications to enhance the image contrast due to their high mass attenuation coefficient. Bismuth (Z- 83) is the nonradioactive, heaviest, nontoxic element available among the other closest neighbors (Hg, Tl, Pb and Po) of the periodic table. We have set out to search for compounds that are hydrolytically stable, more efficient and more amenable in terms of biocompatibility. Moreover this new discovery can significantly reduce the average radiation dose in one CT scan. We have discovered a simple one-step aqueous solution route for preparing biocompatible and ultra-small bismuth oxyiodide BiOI nanoparticles and investigated their potential application as an efficient CT contrast agent. Our ultra-small monodisperse BiOI NPs have excellent water dispersability, thermodynamic stability, kinetic inertness, high biocompatibility and superior attenuation power, suggesting their potential as an organ-specific CT contrast agent that may fill the gap left by the other nanoparticulate and iodine-based CT contrasting agents. The chapter 6 of this dissertation discusses synthesis and characterization of novel nanoparticulate therapeutics and theranostics. D-penicillamine has the highest efficacy, and hence is currently the most widely used drug for WD across the world. We have prepared the D-PEN-conjugated Au NPs of the average size of 16 [special character omited] 2 nm with superb water dispersability, and examined the kinetics and selectivity of copper binding of such NPs in aqueous solution. We also studied the cellular uptake, cytotoxicity and intracellular copper removal of these NPs to demonstrate their potential as a novel cell-penetrable copper detoxifying agent. Our approach of tackling these problems focuses on the development of cell-permeable copper-depleting nanoparticles that can be surface-engineered to be potentially organ-specific when targeting agents are used to form new-generation drugs for WD. The latter part of chapter 6, we describe the synthesis, characterization of zinc analogue of Prussian blue (K2Zn3[Fe(CN) 6]2-ZnPB) for intracellular copper detoxification. (Abstract shortened by ProQuest.).