Improved Photoelectrochemical Performance of WO 3 /BiVO 4 Heterojunction Photoanodes via WO 3 Nanostructuring.

WO/BiVO 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 WO/BiVO photoelectrodes possessing a nanoflake-like morphology have been synthesized through a multistep process and their PEC performance was investigated in comparison to that of WO/BiVO 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 WO underlayer in nanoflake-like WO/BiVO heterojunction electrodes.