Refining the band structure of BiOBr nanosheets through the synergetic effect of VO43− ions replacement and oxygen vacancies for promoted visible-light-driven photocatalysis

Abstract

Normally, the band structure of a photocatalyst can be tuned by surface oxygen vacancies or element doping, however, employing the synergetic effects of surface oxygen vacancies and oxyacid group replacements to regulate the band structure of the photocatalyst is challenging. Here, the band structure of BiOBr nanosheets was regulated by surface oxygen vacancies and VO₃⁻ ions replacement through a hydrothermal VO₃⁻ ions exchange route, in which the VO₃⁻ transform into VO₄³⁻ for BiVO₄ and BiV_1.025O_4+x. The crystal phase of the products evolved from BiOBr, BiOBr/BiVO₄, BiOBr/BiVO₄/BiV_1.025O_4+x, and BiVO₄/BiV_1.025O_4+x accordingly, when gradually increasing the concentration of VO₃⁻ (NH₄VO₃) from 0.05 to 3.0 mmol. In particular, the BiOBr nanosheets with surface oxygen vacancies and VO₄³⁻ ion replacement (by adding 0.05 mmol of VO₃⁻) possessing defective states and more negative conduction band potential could promote visible-light-driven photocatalytic performances of organic contaminants due to the effective separation of charge carriers. This work provides new insight into refining the band structure of photocatalysts and evidential proof of a phase transition through oxyacid exchange.