G-C3N4 quantum dots and Au nano particles co-modified CeO2/Fe3O4 micro-flowers photocatalyst for enhanced CO2 photoreduction

Abstract Wide-light absorption performance and efficient carrier separation ability are the necessary conditions for excellent photocatalytic materials. In this research, g-C3N4 QDs (CN QDs) and Au nano-particles (NPs) co-modified CeO2/Fe3O4 micro-flowers (MFs) photocatalyst (CACeF) has been prepared. CO2 photoreduction experiments showed that the composite had obviously enhanced photoreduction activity and photocatalytic stability. The yields of CO and CH4 over it as catalyst in 4 h is about 5 and 8 times greater than that of pure CeO2. Photoelectrochemical tests showed that the heterojunction between CN QDs and Au NPs can greatly improve the carrier separation ability and the light-utilization efficiency of photocatalysts. Besides, the excellent electronic transmission performance of Au NPs provided a specific channel for the electron transmission, and the strong local surface plasmon resonance (LSPR) of Au NPs resulted in a lot of hot-electrons can directly take part in the CO2 photoreduction. The synergistic effect between CN QDs and Au NPs can further enhance the photocatalytic activity of the photocatalyst. Fe3O4 QDs can ensure the effective recovery and reuse of the composite without affecting the photocatalytic performance of composite. Finally, a potential photoreduction mechanism of CN QDs and Au NPs co-modified CeO2/Fe3O4 MFs photocatalyst were discussed in total.