Synergy Effect of the Enhanced Local Electric Field and Built-In Electric Field of CoS/Mo-Doped BiVO 4 for Photoelectrochemical Water Oxidation.

Bismuth vanadate is a promising material for photoelectrochemical water oxidation. However, it suffers from a low quantum efficiency, poor stability, and slow water oxidation kinetics. Here, we developed a novel photoanode of CoS/Mo-BiVO 4 with excellent photoelectrochemical water oxidation performance. It achieved a photocurrent density of 4.5 mA cm -2 at 1.23 V versus the reversible hydrogen electrode, ∼4 times that of BiVO 4 . The CoS/Mo-BiVO 4 photoanode also exhibited good stability, and the photocurrent density generated by the CoS/Mo-BiVO 4 photoanode did not significantly decrease after light irradiation for 2 h. Upon replacement of part of the V with Mo doping in BiVO 4 , the local electric field around the Mo-O bond was enhanced, thus promoting carrier separation in BiVO 4 . The CoS was deposited on the surface of Mo-BiVO 4 , forming a built-in electric field at the interface. Under the action of the bias electric field and the built-in electric field, the carriers of CoS/Mo-BiVO 4 were efficiently separated in the direction of the inverse type II heterojunction. In addition, CoS improved the light absorption and charge injection efficiency of the CoS/Mo-BiVO 4 photoanode.