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.