Coupling of self-healing atomic layer CoAl-LDH onto Mo:BiVO4 photoanode for fast surface charge transfer toward stable and high-performance water splitting

Herein, Mo doping BiVO4/ultrathin-CoAl-LDH (Mo:BVO/CoAl-LDH-u) photoanode with self-healing property is firstly designed by using the atomic layer CoAl-LDH as cocatalyst to modify Mo:BVO through a simple dipping coating method. The Mo:BVO/CoAl-LDH-u photoanode presents a nearly 100% surface charge separation efficiency and extremely outstanding photocurrent density of 5.8 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (VRHE) without any scavengers. The CoAl-LDH-u intimately contacted with BiVO4 photoanode significantly improves the surface charge transfer efficiency by passivating the surface state and rapidly extracting holes from Mo:BiVO4, and promotes the oxygen evolution reaction (OER) rate by conversion of Co2+ to Co3+ species. Interestingly, the Mo:BVO/CoAl-LDH-u photoanode has the self-healing peculiarity, due to the easy reparation of oxygen defects in CoAl-LDH-u by the cycle of Co3+/Co2+, and hence the photoelectrochemical (PEC) performance can be restored naturally in the air. This work presents a facile approach to fabricate high-efficiency BiVO4 photoelectrode for accelerating the PEC water splitting.