Enhanced photocatalytic activity of oxygen vacancy modulation interfacial electric field in S-scheme heterojunction VO/BiVO4-TiO2 and its mechanism

Abstract

Constructing heterojunction photocatalysts is a promising way to efficiently degrade organic pollutants, while its application is constrained by slow interfacial dynamics. Reported herein is an easy strategy to construct S-scheme heterojunction between BiVO4 with oxygen vacancies (VO) and TiO2. The Vo/BiVO4-TiO2 heterojunction exhibited excellent efficiency in degrading Levofloxacin (LVFX) (99.21 % degradation within 90 min) and significantly enhanced degradation kinetic (4.03 × 10-2min−1), which was 2.6 times than BiVO4-TiO2 (1.53 × 10-2min−1). The mechanism lies in the fact that the introduction of VO into BiVO4 produces impurity bands that reduce its work function, which increases the difference in Fermi energy levels of the heterojunction and, in turn, enhances the Interfacial Electric Field. Based on the experimental and theoretical simulations results, the charge transfer path at the interface of Vo/BiVO4-TiO2 was elucidate. This work reveals the microscopic mechanism of electric field enhancement at heterojunction interface and provides new insights for designing efficient heterojunction photocatalysts.