MoO3/BiVO4 heterojunction film with oxygen vacancies for efficient and stable photoelectrochemical water oxidation

Poor charge transfer and separation rate are the major bottlenecks for the activity and stability of BiVO 4 photoanode. Here, we introduced oxygen vacancies into MoO 3 /BiVO 4 heterojunction film by post-annealing the film in argon-saturated environment for improving its photoelectrochemical (PEC) water oxidation activity and stability. In comparison with the normal MoO 3 /BiVO 4 film, the MoO 3 /BiVO 4 film with oxygen vacancies is of better PEC water oxidation performance. Specifically, a higher photocurrent density of 4.1 mA/cm 2 in 0.1 M Na 2 SO 4 at 1.1 V versus SCE was achieved on the MoO 3 /BiVO 4 film with oxygen vacancies, which is about 200% improved over the normal MoO 3 /BiVO 4 film (1.83 mA cm −2 , at 1.1 V versus SCE). In addition, the MoO 3 /BiVO 4 film with oxygen vacancies shows more stable activity and faster kinetics for water oxidation, without significant activity loss for 5 h reaction at 1.23 V versus RHE. The enhanced performance on such a MoO 3 /BiVO 4 film photoanode can be attributed to that the oxygen vacancies accelerate the charge transfer and separation rate between film/electrolyte interface, and thus improve the water oxidation activity and restrain the anodic photocorrosion simultaneously.