Architecture modification and In3+-doping of WO3 photoanodes to boost the photoelectrochemical water oxidation performance

WO3 photoanodes have been widely utilized for the oxygen evolution reaction (OER) in the photoelectrochemical water splitting system. Herein, the effects of hydrazine hydrate modification and In3+-doping on the physicochemical properties and photocurrent density of the WO3 photoanode prepared by hydrothermally treating at 160 °C followed by calcining at 500 °C are investigated. Among them, the hydrazine hydrate in the hydrothermal solution can serve as a texture regulator, resulting in the formation of WO3 films with the layered architecture stacked by nanosheets dominantly exposed (020) facets, which allows the WO3 films to have faster charge separation and larger specific surface area for OER according to the characterization results of microstructures and photoelectrochemcial behaviors; while the In3+-doping can optimize the energy band structure of WO3 and adjust the work function to increase the driving force of OER based on the ultraviolet photoelectron spectroscopy, Mott–Schottky and open-circuit photovoltage plots. Under the simulated sunlight (AM1.5G) illumination, the designed In3+–WO3(N2H4) photoanode in Na2SO4 solution delivers amaximum incident photon-to-current efficiency of 38.6% at 410 nm and a photocurrent density of 1.93 mA cm−2 at 1.23 V vs. RHE, which is 2.8 and 3.0 times higher than the pristine WO3 photoanode, respectively. This study provides a promising strategy to improve the water splitting performance of nanostructured WO3 photoanodes by altering the architecture and introducing heteroatoms.[graphic not available: see fulltext]