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

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.