Abstract:
Photocataltyic reduction of CO
2 is one of the promising routes in CO
2 conversion and utilization, but the very low CO
2 conversion rate is the biggest hurdle for the process. Developing a new CO
2 reduction reaction system and improving the visible light utilization and separation efficiency of photogenerated electrons and holes are effective ways to solve the above problems. In this work, we designed a CO
2-toluene coupling reaction system to promote the CO
2 reduction reaction. The Ti
1Li
3Al
2-layered dihydroxides (LDHs)/graphite phase carbon nitride (g-C
3N
4) composite with heterojunction structure were synthesized by electrostatic assembly method. And the photoelectric property and photocatalytic properties of Ti
1Li
3Al
2-LDHs/g-C
3N
4 composite were explored in CO
2-toluene reduction reaction system. The results show that CO
2 is reduced to CO, and toluene is oxidized to benzyl alcohol, benzaldehyde and benzyl benzoate in the photocataltyic coupling reaction system. Benzaldehyde and benzyl alcohol content can reach 4.80 and 4.70 mmol/g
cat. This is mainly because the g-C
3N
4 can extend the absorption of Ti
1Li
3Al
2-LDHs from the ultraviolet region to the visible region, and improve the dispersion of Ti
1Li
3Al
2-LDHs which provide more active sites for photocatalytic reactions. Moreover, the S-type heterojunction is formed in the interface of Ti
1Li
3Al
2-LDHs/g-C
3N
4, which is conducive to the transfer of photogenerated electrons at the interface and improves the separation efficiency of photogenerated electrons and holes. And toluene can be used as an organic substrate to accelerate the rate of hole consumption and stimulate the CO
2 reduction reaction. This work provides a new idea for the synergistic reaction between CO
2 reduction and small molecular organics.