Papers by Keyword: Photoelectrochemical

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Authors: Yue Ke, Catherine Moisson, S. Gaan, R.M. Feenstra, Robert P. Devaty, Wolfgang J. Choyke
Abstract: The effects of initial surface morphology on the early stages of porous SiC formation under highly biased photoelectrochemical etching conditions are discussed. We etched both Si-face and C-face polished n-type 6H SiC with different surface finishes prepared either by mechanical polishing or by chemical mechanical polishing at NOVASiC. For both Si-face and C-face porous SiC samples, a variety of surface and cross sectional porous morphologies, due to different surface finishes, are observed. The proposed explanation is based on the spatial distribution of holes at the interface of the SiC and electrolyte inside the semiconductor.
Authors: Bernard Baps, Manuela Eber-Koyuncu, Metin Koyuncu
Authors: Yue Ke, Fei Yan, Robert P. Devaty, Wolfgang J. Choyke
Abstract: A hybrid columnar and dendritic porous structure has been developed in n-type 6H SiC using photoelectrochemical etching with proper control of the applied voltage and current density. The diameter of the formed columnar pores is around 200-500 nm. A possible formation mechanism due to the spatial distribution of holes and the HF concentration gradient in the pores is proposed. A self-supporting film with this morphology is a promising candidate for protein dialysis.
Authors: Nordin Sabli, Zainal Abidin Talib, Mat Yunus Wan Mahmood, Zulkarnain Zainal, Hikmat S. Hilal, Masatoshi Fujii
Abstract: CuZnSnSe thin films were deposited by thermal vacuum evaporation with and without argon gas stream at room temperature. Effect of argon gas on surface morphology and on photoelectrochemical (PEC) characteristics of the films was studied. The electrodes prepared under argon gas showed better enhanced characteristics, due to slower nucleation and growth due to dilution effect of the inert gas. While both electrodes showed soundly good PEC behaviors in a hexacyanoferrate(III)/hexacyanoferrate(II) redox couple, the electrode with argon gas showed 20 fold enhancement in photoactivity, compared to the one without argon gas. The results manifested thin film electrode performance can be enhanced simply by inclusion of argon inert gas inside the preparation chamber, with no need for other procedures such as annealing.
Authors: Rekha Dom, G. Siva Kumar, Hyun Gyu Kim, Shrikant V. Joshi, A. Sadananda Chary, Pramod H. Borse
Abstract: Development of efficient photoanodes for water splitting under solar light is desirable to surmount the possible fuel crisis in future. Ferrite systems, with their excellent visible light absorption capability, stability, non-toxicity, cost-effectiveness and abundance, are being preferred to titanates, niobates and sulfides. The present work briefly reviews the modified form of ferrites. Additionally, ZnFe2O4 an n-type semiconductor with the low band gap (~1.9eV) has been considered as special case of visible light PEC application. The work further emphasizes on the utilization of solution processed techniques to develop the ferrite photoanodes. The tuning of photoanode properties by virtue of electrode fabrication parameters say deposition parameters viz., precursor concentration, pH, stoichiometry has been reviewed and discussed.
Authors: Nordin Sabli, Zainal Abidin Talib, Mat Yunus Wan Mahmood, Zulkarnain Zainal, Hikmat S. Hilal, Mohd Shahril Husin
Abstract: The differences in structural, compositional and photoelectrochemical properties for SnSe films annealed at different temperatures, under nitrogen atmosphere, were studied. Annealing the film electrode significantly improved its crystallinity but lowered its photoresponse. The photoresponse lowering was thus attributed to lowering in the defect concentrations.
Authors: Fang Gong Cai, Feng Yang, Yong Zhao
Abstract: The crystallization of anatase from amorphous TiO2 nanotube arrays (TNTs) has been carried out by annealing in air and hydrothermal treatment in water. The morphology and crystalline phase of obtained TNTs membranes were detailedly characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The surface electronic structure and photoelectrochemical properties (PEC) of TNTs obtained by different crystallization methods were investigated. The results show that the TNTs electrode crystallized by hydrothermal treatment method demonstrate a broader surface photovoltage response range and higher photoelectrochemical properties than that of TNTs electrode directly annealed in air due to effective Ti3+ sites.
Authors: Pattranit Thongthep, Somporn Moonmangmee, Chatchai Ponchio
Abstract: In this study, we can fabricate Cu2O on F-doped SnO2 coated glass (FTO) substrates as photocathode for hydrogen evolution reaction by electro-deposition techniques. Cyclic voltammetry as a new deposition method was studied to fabricate Cu2O photocathode in a mixed solution of Cu (NO3)2 and KNO3 under a condition of low temperature and without pH value adjustment. Amperometry as a previous method was used to compare for Cu2O electrode fabrication under the situation of pH adjustment and higher temperature condition. A photocurrent from hydrogen evolution reaction was performed by keep potential at-0.2 V in 0.1 M Na2SO4 under visible irradiation comparing with both fabricated method. The Cu2O photocathode from cyclic voltammetry deposition method presents photoelectrocatalytic activity higher than that of amperometry deposition method with the optimum conditions. This electro-deposition technique represents the excellent method with simple, fast and low cost of Cu2O photocathode fabrication for photoelectrochemical hydrogen evolution reaction.
Authors: Mee Ching Ung, Rachel Fran Mansa, Coswald Stephen Sipaut, Jedol Dayou
Abstract: Natural dyes were extracted from the plant species Etlingera elatior, Duranta erecta and Amaranthus spp. that were collected from Keningau and Tambunan, Sabah, Malaysia. The possibility of photon-electron conversion was then assessed based on their absorption ability in the region of wavelength between 400-900nm. In addition, FT-IR analysis was carried out to determine if functional groups exists in their extracts. Finally, the DSSCs were assembled and their efficiency measured. It shows the successful conversion from visible sunlight to electricity by using extracts from Etlingera elatior, Duranta erecta and Amaranthus spp. as raw natural dye sensitizers in Dye Sensitized Solar Cells (DSSCs) with efficiency of 0.1% ,0.06% and 0.04%, respectively. This result shows that local natural dyes can be used as sensitizer in DSSCs. However, further investigations are required to improve the efficiency.
Authors: Dan Yan, Wei Dong Shi, Wei Qiang Fan
Abstract: Cu (OH)2@TiO2 nanowire arrays (NWAs) on the Fluorine-doped tin oxide (FTO) substrates had been fabricated via an simple and facile deposition method. The as-prepared Cu (OH)2@TiO2 NWAs were subsequently characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD), UVVis diffuse reflectance spectra (DRS), X-ray photoelectron spectrometer (XPS) and photoelectrochemical measurements. This results suggested that the Cu (OH)2@TiO2 NWAs efficiently impeded the recombination between photoelectrons and holes. Therefore, this approach would afford a simple, effective, facile and low-cost method for preparation photoanode, which would enhance the hydrogen generating capability of TiO2 from water splitting.
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