Cu₃Mo₂O₉/BiVO₄ Heterojunction Films with Integrated Thermodynamic and Kinetic Advantages for Solar Water Oxidation

Abstract

The development of BiVO4-based heterojunction photoanodes with thermodynamic and kinetic advantages is one of the breakthrough directions to fulfill the potential of BiVO4 for solar water splitting. Here, we designed and investigated a Cu3Mo2O9/BiVO4 heterojunction film photoanode that consisted of p-type Cu3Mo2O9 nanoparticles and an n-type BiVO4 film for water oxidation. Compared to the BiVO4 film, the resultant Cu3Mo2O9/BiVO4 heterojunction film shows better activity and stability during water oxidation owing to the synergistic effect of the p–n heterojunction and Cu3Mo2O9 cocatalysis. Specifically, the formed p–n heterojunctions of Cu3Mo2O9/BiVO4 are thermodynamically favorable to the separation and transfer of photoexcited holes–electrons, which result in a higher activity of the Cu3Mo2O9/BiVO4 photoanode for water oxidation. Meanwhile, the Cu3Mo2O9 electrocatalysis could be initiated by the photoexcited holes of BiVO4, which can enhance the water oxidation kinetics and stability of the Cu3Mo2O9/BiVO4 film photoanode. Our study provides a reference to design BiVO4-based heterojunction photoanodes with integrated advantages in thermodynamics and kinetics for water splitting.