Metal (Ni2+/Co2+) sulfides modified BiVO4 for effective improvement in photoelectrochemical water splitting

The performance of BiVO 4 for photoelectrocatalytic (PEC) water decomposition is commonly limited by reaction kinetics. In this work, NiS and CoS nanospheres were respectively loaded on BiVO 4 thin films (NiS/BiVO 4 and CoS/BiVO 4 composites) to improve its reaction kinetics for PEC water decomposition. Both physical and chemical properties of these composites were characterized by XRD , SEM, TEM, PL and UV-DRS. The photoelectric properties of the samples were verified by testing LSV , i-t, EIS and IPCE. The formation of the composites can effectively prevent the recombination of carriers and consequently accelerate the separation of electrons and holes. NiS/BiVO 4 and CoS/BiVO 4 can reach photocurrent of 2.1 mA cm −2 and 2.7 mA cm −2 under light respectively, at 1.23 V vs. RHE, which are 1.75 times and 2.25 times that of BiVO 4 (1.2 mA cm −2 ). The hydrogen production of the NiS/BiVO 4 and CoS/BiVO 4 photoanodes was 4.7 and 7.3 times higher than that of BiVO 4 photoanode, respectively.