Unveiling the role of surface heterostructure in Bi0.5Y0.5VO4 solid solution for photocatalytic overall water splitting

The solid solution photocatalyst plays a vital role in designing the one-step excitation water splitting system. However, the co-existence of the evolution of surface heterostructure together with the gradual formation of solid solutions makes it difficult to distinguish the inherent role of solid solution and surface structure in OWS reaction. Herein, Bi 0.5 Y 0.5 VO 4 solid solution was synthesized through a fine-tuned co-precipitation procedure at room temperature, which acted as starting materials for further annealing treatment. Systematic characterizations revealed that variations in surface B-V-O domain at different temperatures induced the generation of particular heterogeneous structures in the solid solution surface. After annealing at 600 °C, the surface V-rich amorphous layer on Bi 0.5 Y 0.5 VO 4 delivered functional electron trapping and optimized reaction dynamics, leading to enhanced OWS activity. In contrast, a nano-junction alignment formed at 800 °C near the surface resulted in an inappropriate band structure and poor charge dynamics, finally suppressing the OWS activity.