In situ self-assembled S-scheme BiOBr/pCN hybrid with enhanced photocatalytic activity for organic pollutant degradation and CO2 reduction

Researchers have devoted themselves to improving and developing efficient photocatalysts and applying them to practical applications, such as organic pollution degradation and CO2 reduction. In this work, hollow hierarchical BiOBr microspheres were immobilized on the surface of protonated g-C3N4 (pCN) to form a unique S-scheme heterostructure via an in situ hydrothermal method. The synthesized samples exhibited remarkable photocatalytic activity for the degradation of rhodamine B (RhB) and the reduction of CO2 to methanol. The characterization results indicate that pCN is an effective support for hollow hierarchical BiOBr by enhancing the adsorption and transformation capability for RhB and CO2 molecules, and it improves the separation of photogenerated charge carriers by forming a Schottky barrier. Additionally, the introduction of pCN affected the morphology of BiOBr and provided a larger specific surface area. Hence, the pCN/BiOBr hybrid showed remarkably improved degradation of RhB and reduction of CO2 under visible-light irradiation. Specially, the 10% pCN/BiOBr hybrid had the best photocatalytic activity for RhB degradation (95.23%, 30 min) and CO2 reduction (1068.07 μmol/gcat, 4 h), which was approximately 1.70-fold and 2.56-fold, respectively, that of BiOBr. A possible S-scheme electron transform pattern is proposed to explain the photocatalytic mechanism of the 10% pCN/BiOBr hybrid.