Efficient infrared light induced CO2 reduction with nearly 100% CO selectivity enabled by metallic CoN porous atomic layers

Conductors hold promise for applications in infrared-light CO2 reduction to fuels. However, their extremely high carrier densities unfortunately result in strong electron–hole recombination. Herein, an ultrathin conductor with porous structure is designed to prolong the lifetime of photoexcited electrons. Taking the synthetic metallic CoN porous atomic layers as an example, synchrotron-radiation photoelectron spectroscopy and UV-vis-NIR spectroscopy uncover they could realize simultaneous CO2 reduction and H2O oxidation under infrared-light irradiation. Ultrafast transient absorption spectroscopy first unveils the infrared-light excited electrons undergo sequential intraband relaxation and interband recombination processes, where the 9- and 1.6-fold increased time in these two processes verifies the Na2S solution dramatically prolongs the electron lifetime. The metallic CoN porous atomic layers exhibit infrared-light induced CO2 reduction with nearly 100% CO selectivity, while the CO evolution rate is increased by 50 times upon adding Na2S solution. This study affords possibilities for achieving high-efficiency infrared-light driven CO2 reduction performance.