Charge Compensation Promotes Reaction Activity, CO Selectivity, and Charge Carrier Lifetime of CO2 Photoreduction on Crystalline Carbon Nitride

Photocatalytic CO2 reduction reaction (CO2RR) is an effective pathway for high value-added chemicals. Poly (triazine imides) (PTI) have a great potential for photocatalytic CO2RR due to its high crystallinity. We have codoped PTI with nonmetals B and S, in which the charge compensation between B and S forms a shallow "donor-acceptor pair". The charge compensation effect regulates the polarity of Lewis acid-base pairs so that more electrons localize in the pyridine N, which facilitates the CO2 hydrogenation and improves both the activity and the selectivity of CO2RR to CO. Furthermore, the hydrogen source of the reaction is the adsorbed H* rather than the substrate H from PTI. Through the nonadiabatic molecular dynamics simulations, although B and S codoping PTI (B-S1/PTI) has a larger nonadiabatic coupling and a narrower energy gap than B doping PTI (B/PTI), a fast decoherence rate prolongs the nonradiative recombination time and carrier lifetime of B-S1/PTI, which improves its catalytic efficiency of CO2RR. This work reveals that the charge compensation effect of nonmetals enhances the photocatalytic CO2RR performance and prolongs the charge carrier lifetime.