Effect of Surface Self-Heterojunction Existed in Bi_xY_1–xVO₄ on Photocatalytic Overall Water Splitting

Bi_xY_1–xVO₄ solid solution, with absorption edge about 410 nm, is a new visible light photocatalysts based on V with d⁰ electron configuration for overall water splitting. However, Bi_xY_1–xVO₄ prepared by solid state reaction always shows low photocatalytic activity and bad repeatability. In this paper, diluted acid was introduced to modify the Bi_xY_1–xVO₄ prepared by solid state reaction. The photocatalytic activity of Bi_xY_1–xVO₄ can be increased nearly four times after diluted acid treatment. The apparent quantum efficiency for overall water splitting at 380 nm is 3.4%. The enhanced photocatalytic water splitting activity is mainly attributable to the disappearance of BiO_y clusters on the surface of Bi_xY_1–xVO₄. The adverse effects for water splitting induced by BiO_y clusters is explained by a novel surface self-heterojunction built between BiO_y clusters and Bi_xY_1–xVO₄. Without diluted acid treatment, BiO_y clusters on the surface could capture photogenerated electrons by this surface self-heterojunction, which is bad for water splitting due to its lower conduction band.