Switching charge transfer of g-C3N4/BiVO4 heterojunction from type II to Z-scheme via interfacial vacancy engineering for improved photocatalysis

Abstract

Constructing type II heterojunction is an efficient strategy to enhance the light absorption and promote the charge transport. However, the improvement effect is limited by the decreased redox ability of charge carriers. The rational design of heterojunction from type II to Z-scheme is expected to overcome this obstacle. Herein, we demonstrate that the introduction of interfacial oxygen vacancies (OVs) can switch charge transfer of g-C3N4/BVO heterojunction from type II to Z-scheme. The interfacial OVs acted as the reactive center of charge carriers to quench the electrons of BVO and holes of g-C3N4, thereby promoting charge separation and migration. As a result, the interfacial OVs mediated Z-scheme g-C3N4/BVO heterojunction kept the strong oxidation/reduction potential of two single-component photocatalysts thereby significantly enhancing the photodegradation of tetracycline and CO2 photoreduction. The kinetic constant of tetracycline degradation on the optimal g-C3N4/BVO-20 sample was 2.04-fold and 2.29-fold higher than those on g-C3N4 nanosheets and pure BVO, respectively. This work provides a feasible strategy by the interfacial vacancy engineering of heterojunction for enhanced photocatalysis.