Improved Photoelectrochemical Performance of WO₃/BiVO₄ Heterojunction Photoanodes via WO₃ Nanostructuring

Abstract

WO3/BiVO4 heterojunction photoanodes can be efficiently employed in photoelectrochemical (PEC) cells for the conversion of water into molecular oxygen, the kinetic bottleneck of water splitting. Composite WO3/BiVO4 photoelectrodes possessing a nanoflake-like morphology have been synthesized through a multistep process and their PEC performance was investigated in comparison to that of WO3/BiVO4 photoelectrodes displaying a planar surface morphology and similar absorption properties and thickness. PEC tests, also in the presence of a sacrificial hole scavenger, electrochemical impedance analysis under simulated solar irradiation, and incident photon to current efficiency measurements highlighted that charge transport and charge recombination issues affecting the performance of the planar composite can be successfully overcome by nanostructuring the WO3 underlayer in nanoflake-like WO3/BiVO4 heterojunction electrodes.

Ultrathin and Conformal TiOx Overlayers on WO3 Photoelectrodes for Simultaneous Surface Trap Passivation and Heterojunction Formation

“…Generally, the charge recombination processes may occur at the photoelectrode–conducting substrate interface, in photoelectrode bulk, and at the photoelectrode–electrolyte interface. − To suppress these charge recombination pathways, various strategies have been reported. For charge recombination at the photoelectrode–conducting substrate interface, a compact underlayer has been proven to be efficient in preventing back reactions and enhancing majority carrier collection. , For slow reaction kinetics-induced surface recombination, depositing efficient water oxidation or reduction electrocatalysts at the photoelectrode surface would help.…”