Charge separation via synergy of homojunction and electrocatalyst in BiVO4 for photoelectrochemical water splitting

Abstract

Bismuth vanadate (BiVO4) as oxygen evolution photoanodes in photoelectrochemical (PEC) water splitting is hampered by the severe charge recombination and sluggish kinetic reaction. Herein, we successively construct a novel homogenous BVO/BiVO4 photoanodes consisting of BiVO4 nanodots (BVO) with exposed (011) crystal facet on BiVO4 substrate that did not only creates tunable (011)/(110) crystal planes upon homogeneous interfacial contact but also demonstrates an unprecedented photocurrent density with outstanding performance. Theoretical calculations clearly reveal that the tunable (011)/(110) crystal facet facilitates the charge separation efficiency and water splitting kinetics. Furthermore, the photocurrent density of the homogenous BVO/BiVO4 is further enhanced by additional photo-deposition of NiFeOx electrocatalyst layer (denoted NiFeOx/BVO/BiVO4). Consequently, the optimized NiFeOx/BVO/BiVO4 photoanodes not only reaches an unprecedented photocurrent density of 6.40 mA cm−2 at 1.23 V versus reversible hydrogen electrode (RHE) under simulated AM 1.5G illumination, but also generates an outstanding durability. This work endows a new environmentally friendly and effective path for improving PEC water splitting of BiVO4 photoanodes.