Photoelectrochemical Behavior of Nanostructured WO3 Thin-Film Electrodes: The Oxidation of Formic Acid (original) (raw)
Related papers
Tuning Structural Properties of WO3 Thin Films for Photoelectrocatalytic Water Oxidation
Catalysts
The preparation of tungsten oxide (WO3) thin film by direct current (DC) reactive sputtering magnetron method and its photoelectrocatalytic properties for water oxidation reaction are investigated using ultraviolet-visible radiation. The structural, morphological, and compositional properties of WO3 are fine-tuned by controlling thin film deposition time, and post-annealing temperature and environment. The findings suggest that the band gap of WO3 can be controlled by adjusting the post-annealing temperature; the band gap decreased from 3.2 to 2.7 eV by increasing the annealing temperature from 100 to 600 °C. The theoretical calculations of the WO3 bandgap and the density of state are performed by density functional theory (DFT). Following the band gap modification, the photoelectrocatalytic activity increased and the maximum photocurrent (0.9 mA/cm2 at 0.6 VSCE) is recorded with WO3 film heated at 500 °C. The WO3 film heated under air exhibits much better performance in photoelectr...
Solar Energy Materials and Solar Cells, 2010
Different chemical routes for obtaining nanostructured WO 3 on transparent conductive oxides have been tried by considering the Santato-Augustynski recipe as a main guideline. The preparation started from tungstate salts as precursors and involved different organic dispersing agents. Calcination in air at 550 1C produced the final oxide. Aim of this work is to test the oxide materials as photoanodes for the photo-electrochemical water splitting. WO 3 is a wide bandgap semiconductor, able to transport photogenerated carriers under irradiation, provided that it has a good crystalline structure. The morphology and the crystal size of the obtained WO 3 nanoparticles have been investigated by SEM and XRD. This work shows that the particle size of the WO 3 film decreases with increase in molecular weight of the organic dispersing agents. The current-voltage characteristic curves of WO 3 -based electrodes have been obtained by biasing a photo-electrochemical cell with an external voltage ramp, both in the dark and under simulated solar irradiation. Results showed that under incident irradiance a noticeable photocurrent density is obtained with a reasonably steep current-voltage slope and with a plateau current of the order of 1.6-1.8 mA/cm 2 under incident 0.14 W/cm 2 AM 1.5 irradiation.
Electrochemical Synthesis-Dependent Photoelectrochemical Properties of Tungsten Oxide Powders
ChemEngineering
A rapid, facile, and environmentally benign strategy to electrochemical oxidation of metallic tungsten under pulse alternating current in an aqueous electrolyte solution was reported. Particle size, morphology, and electronic structure of the obtained WO3 nanopowders showed strong dependence on electrolyte composition (nitric, sulfuric, and oxalic acid). The use of oxalic acid as an electrolyte provides a gram-scale synthesis of WO3 nanopowders with tungsten electrochemical oxidation rate of up to 0.31 g·cm−2·h−1 that is much higher compared to the strong acids. The materials were examined as photoanodes in photoelectrochemical reforming of organic substances under solar light. WO3 synthesized in oxalic acid is shown to exhibit excellent activity towards the photoelectrochemical reforming of glucose and ethylene glycol, with photocurrents that are nearly equal to those achieved in the presence of simple alcohol such as ethanol. This work demonstrates the promise of pulse alternating...
Scientific reports, 2017
It is highly desired to improve the photoelectrochemical (PEC) performance of nanosized WO3 by artificially modulating the photogenerated electrons and holes simultaneously. Herein, WO3 nanoplates have been successfully prepared by a simple one-pot two-phase separated hydrolysis-solvothermal method, and then co-modified with RGO and phosphate acid successively by wet chemical processes. Subsequently, the as-prepared WO3-based nanoplates were immobilized on the conductive glasses to explore the PEC activities for both water oxidation to evolve O2 and phenol degradation. It is clearly demonstrated that the co-modified WO3 nanoplates exhibit significantly improved PEC activities compared with pristine WO3, especially for that with the amount-optimized modifiers by ca. 6-time enhancement. Mainly based on the evaluated hydroxyl radical amounts produced and the electrochemical impedance spectra, it is suggested that the improved PEC activities are attributed to the greatly enhanced photog...
Electrochimica Acta, 2010
With the aim of improving the performance and extending the range of applications of mesoporous WO 3 films, which were initially developed for the photoelectrochemical oxidation of water, we investigated the effect of a number of dopants (lithium, silicon, ruthenium, molybdenum and tin) upon the transparency, crystallinity, porosity and conductivity of the modified films. Tin, molybdenum and silicon were shown to improve the electrochromic behaviour of the layers whereas ruthenium enhanced considerably the electronic conductivity of the WO 3 films. Interestingly, most of the dopants also affected the film morphology and the size of WO 3 nanocrystals. X-ray photoelectron spectra revealed absence of significant segregation of doping elements within the film. Raman analyses confirmed that the monoclinic structure of WO 3 films does not change upon substitutional cation doping; thus, the crystallinity of WO 3 films is maintained.
Photoactive WO3 and Se-WO3 thin films for photoelectrochemical oxidation of organic compounds
Journal of Applied Electrochemistry, 2010
Thin films of bare and Se-containing tungsten trioxide (WO 3) on AISI304-type stainless steel were prepared by electrochemical deposition using peroxy-tungstate solutions. The obtained films were characterized by X-ray diffraction, photoelectron spectroscopy, scanning electron microscopy, thermal and photovoltammetry analyses. The oxidation of methylene blue, phenol, and methanol was used to evaluate the photoelectrocatalytic activity of the prepared films. It has been established that the incident photon-to-current efficiency (IPCE) in 0.1-M K 2 SO 4 decreases as the concentration of methylene blue and phenol increases. On the contrary, the IPCE values increase with the increase in initial concentration of methanol. The bulk electrolysis experiments revealed that the prepared films are stable and can be used for photoelectrochemical oxidation of methanol.