Highly efficient photocatalytic degradation of rhodamine B by conical graphene quantum dots/cerium oxide composite

Abstract Graphene Quantum Dots (GQDs) are graphene nanoparticles with a particle size of less than 100 nm. GQDs are used as sensitizers for semiconductor catalytic materials and have a significant enhancement effect on the catalytic performance of the catalyst. We have prepared GQDs/CeO2 composites to improve the catalytic performance of CeO2. GQDs in the GQDs/CeO2 composites were uniformly coated around each CeO2 crystal, which effectively increased the reactive sites and effective contact interfaces. The composite GQDs-4.5/CeO2 absorption edge was broadened to 475 nm, with extremely low electron-hole recombination rate and optimal photoelectric performance. The composite material formed a heterogeneous structure with staggered energy levels. The photogenerated electrons were transferred from the GQDs conduction band to the CeO2 conduction band, which effectively prolonged the carrier lifetime, showed enhanced photocatalytic activity, and decomposed Rhodamine B (RhB) photocatalytic reaction under visible light. The reaction rate constant was up to 13.8 times that of pure CeO2.