Highly-interspersed biomass-derived carbon quantum dots onto floral CoAl-LDH for significantly enhanced CO2 photoreduction into CO and CH4

Stimulating photocatalytic activity of layered double hydroxides (LDHs) have been being as a research hotspot in photocatalysis. Quantum dots doping is a well acknowledged strategy to utilize their photoelectric superiorities to overcome the intrinsic defects of pristine LDHs. In this work, waste biomass-derived carbon quantum dots (B-CQDs)-interspersed CoAl-LDH photocatalysts (B/CALs) are successfully prepared by means of a simple hydrothermal method from green and renewable points of view. The introduction of B-CQDs significantly broadens the light absorption range and capacity of CoAl-LDH. As the terminal electron acceptor, the highly-dispersed B-CQDs can effectively prolong the lifetime of photogenerated charge carriers and promote the separation of photogenerated electron-hole pairs. No assistance from any sacrificial agent, the optimal sample of B/CAL-2 exhibits significantly enhanced photoreduction activity of CO2-to-CO and CH4, 6.4- and 7.5-fold higher than those of the pristine CoAl-LDH, respectively, and also surpassing many reported high-level LDHs counterparts. Such an uncomplicated case guides a green and feasible route to modify semiconductor materials with renewable biomass, which is expected to be applied to others for enhanced photocatalytic activity.