Bismuth Vanadate Capable of Driving One-Step-Excitation Photocatalytic Overall Water Splitting

Abstract

Solar-driven one-step-excitation overall water splitting is one of the most straightforward ways of achieving scalable solar hydrogen production. Despite its advantage in visible-light response and stability, the pristine bismuth vanadate (BiVO4) alone is not capable of achieving overall water splitting due to its conduction band energy level being insufficient for the proton reduction reaction, further limited by the severe charge recombination. Here, we demonstrate the three-dimensionally ordered macroporous BiVO4 with a carefully enlarged bandgap of 2.58 eV and a conduction band energy of −0.49 eV versus normal hydrogen electrode at pH 7.0. On loading Rh/Cr2O3 as a hydrogen evolution cocatalyst, the stochiometric evolution of hydrogen and oxygen in a recyclable manner is accomplished under visible light with an apparent quantum yield of 0.47% at 400 nm. Further study by Kelvin probe force microscopy reveals an intensified internal electric field with a downward band bending from the interconnection part to the internal wall of the periodic porous structure upon loading the cocatalysts. Our findings transform BiVO4 from a typical water oxidation photocatalyst into a new paradigm for single-component photocatalysts for overall water splitting.