Carbon quantum dots from tea enhance z-type BiOBr/C3N4 heterojunctions for RhB degradation: Catalytic effect, mechanisms, and intermediates

The environmental crisis is an important factor that restricts human development. Biomass-derived carbon is an excellent material for the treatment of organic pollutants; however, realization of the energy band regulation of semiconductor photocatalysts remains challenging. Herein, we used green tea as a raw material to obtain different-colored carbon dots and hydrothermal carbon and introduced the C3N4/BiOBr Z-scheme heterostructure for enhancing electron transfer and band regulation. The experimental results show that the material exhibits good photocatalytic performance. 98.48% of rhodamine B (RhB) was degraded within 15 min by 20 wt% red light emitting carbon quantum dot doped C3N4/BiOBr, indicating that its performance is 4.07 times that of BiOBr. The electron spin resonance indicates that the composite material generates ·OH and ·O2− radicals and the reaction mechanisms of the catalyst and the intermediate from the RhB degradation. This study provides a new strategy for the development of biomass-derived carbon photocatalysis.