Carbon quantum dots and interfacial chemical bond synergistically modulated S-scheme Mn0.5Cd0.5S/BiOBr photocatalyst for efficient water purification

Devising robust S-scheme photocatalysts is of central importance for achieving high-efficient micropollutant decontamination. However, the conscious optimization of S-scheme system with high performance remains a prime challenge. Herein, carbon quantum dots (CDs) and Mn 0.5 Cd 0.5 S (MCS) are mounted on BiOBr (BOB) microspheres, establishing an advanced S-scheme heterojunction with interfacial Bi-S bond. The interfacial Bi-S bonds function as superb channels at atomic-scale to abate the energy barrier for S-scheme charge transportation. Meanwhile, CDs serve as electron collectors to preserve highly reductive electrons from MCS, further augmenting the spatial separation of photo-carriers. Therefore, the optimized CDs/MCS/BOB (MBC) heterojunction manifests significantly strengthened tetracycline hydrochloride (TC) destruction activity and its reaction rate constant is approximately 3.1, 2.2, 2.1, and 1.5 folds that than that of MCS, BOB, BOB/CDs and MCS/BOB. In addition, MBC exhibits high stability and significant resistance to environmental interferences. The toxicology evaluation confirms the effective abatement of toxicity of TC after treatment. This achievement demonstrates the benefits of CDs-optimized S-scheme photosystems with chemical bonds for photocatalytic water decontamination. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.