Synthesis of g-C3N4/Co3O4@BiVO4 double S-scheme heterojunction photocatalyst for enhanced Rhodamine B degradation with simulated sunlight

Abstract

The g-C3N4/Co3O4@BiVO4 photo-catalyst was synthesized by green co-precipitation method and used for photocatalytic degradation of Rhodamine B (RhB). It was shown that Co3O4 and BiVO4 form a p-n heterojunction and the band gap energy decreases from 2.578 eV for BiVO4 to 1.564 eV for Co3O4@BiVO4. However, the band gap reduction does not have a significant effect through the g-C3N4 loading. g-C3N4/Co3O4@BiVO4 is more efficient than BiVO4 and Co3O4@BiVO4 at photodegradation of RhB. With a catalyst dose of 0.8 g/L, the removal rate reached 52.6 % after 60 min of simulated sunlight irradiation. The RhB degradation follows a pseudo first-order kinetic law. The S-scheme mechanism was considered in, where g-C3N4 provides a new migration pathway for photoelectrons, favoring the production of electronshole pairs and hydroxyl radicals, as well as the production of superoxide radicals. This study provides a new idea and a new approach for the practical application of BiVO4 photocatalysts.