Photoelectrochemical water splitting using WO₃ photoanodes: the substrate and temperature roles

Abstract

The influence of the substrate on the performance of WO3 photoanodes is assessed as a function of the temperature. Two samples were studied: WO3 deposited on a FTO glass and anodized on a tungsten foil. Current-voltage curves and electrochemical impedance spectroscopy techniques were used to characterize these samples between 25 °C and 65 °C. The photocurrent-density increased with temperature for both samples and the onset potential shifted to lower potentials. However, for WO3/FTO, a negative shift of the dark current onset was also observed. The intrinsic resistivity of this substrate limits the photocurrent plateau potential range. On the other hand, this behavior was not observed for WO3/metal. Therefore, the earlier dark current onset observed for WO3/FTO was assigned to the FTO layer. The optimal operating temperatures observed were 45 °C and 55 °C for WO3/FTO and WO3/metal, respectively. For higher temperatures, the bulk electron-hole recombination phenomenon greatly affects the overall performance of WO3 photoanodes. The stability behavior was then studied at these temperatures over 72 h. For WO3/FTO, a crystalline-to-amorphous phase transformation occurred during the stability test, which may justify the current decrease observed after the aging period. The WO3/metal remained stable, maintaining its morphology and good crystallinity. Interestingly, the preferential orientation of the aged crystals was shifted to the (-222) and (222) planes, suggesting that this was responsible for its better and more stable performance. These findings provide crucial information for allowing further developments on the preparation of WO3 photoanodes, envisaging their commercial application in PEC water splitting cells.

Promoting Oxygen Evolution Reaction of Co‐Based Catalysts (Co3O4, CoS, CoP, and CoN) through Photothermal Effect

“…The fitted Nyquist plot obtained at the high frequency range is associated with the charge‐transfer resistance ( R ct ), which is closely related to the OER process. The R ct of Co 3 O 4 electrode with 808 nm irradiation (Co 3 O 4 ‐5) is 2.3 Ω, which is much lower than that of bare Co 3 O 4 electrode without NIR irradiation ( R ct = 5.2 Ω), attributed to the faster carrier transport at high temperature induced by NIR laser irradiation . Such observations confirm the important role of PE in promoting the electrical conductivity during the OER process.…”

3D Branched Ca‐Fe2O3/Fe2O3 Decorated with Pt and Co‐Pi: Improved Charge‐Separation Dynamics and Photoelectrochemical Performance

“…[1][2][3] Sincet he pioneering work by Fujishima andH onda concerning the n-type TiO 2 photoanode, [1] efficient photoelectrodes such as metal oxides( a-Fe 2 O 3 , [4] BiVO 4 , [5] WO 3 [6] )h ave received considerable attention for overall water splitting. [1][2][3] Sincet he pioneering work by Fujishima andH onda concerning the n-type TiO 2 photoanode, [1] efficient photoelectrodes such as metal oxides( a-Fe 2 O 3 , [4] BiVO 4 , [5] WO 3 [6] )h ave received considerable attention for overall water splitting.…”

Ruthenium oxide/tungsten oxide composite nanofibers as anode catalysts for the green energy generation of Chlorella vulgaris mediated biophotovoltaic cells

“…It may collectively increase the interfacial resistance of a BPV system, urging its composite formation with an electrochemically active catalyst. On the other side, tungsten oxide (WO 3 ) is regarded as a suitable candidate for overwhelming the limitations of RuO 2 nanostructures owing to its band gap of 2.5–2.7 eV, long minority carrier diffusion length (500 nm–6 μm), virtuous electron transport properties, biological and chemical inertness, and environmental benign characteristics . The integration of above materials in the form of a nanocomposite could substantially improve their structural stabilities, which may effectively overwhelm their individual limitations in BPV environment.…”