Nitrogen‐Bridged S−N−Cu Sites for CO2 Photoreduction to Ethanol with 99.5% Selectivity in Pure Water

Solar‐driven CO2 reduction to ethanol is extremely challenging due to the limited efficiency of charge separation, sluggish kinetics of C−C coupling, and unfavorable formation of oxygenate intermediates. Here, we elaborately design a red polymer carbon nitride (RPCN) consisting of S−N and Cu−N4 dual active sites (Cu/S‐RPCN) to address this challenge, which achieves an impressive ethanol evolution rate of 50.4 µmol g‐1 h‐1 with 99.5% selectivity for CO2 photoreduction in pure water. Cu and S atoms within the Cu−N−S configuration can serve as trapping centers for electrons and holes, respectively, providing spatial separation for photogenerated charge carriers. The incorporation of S atoms optimizes the adsorption of *CO on Cu atoms and reduces the energy barrier for the formation of *CO−COH intermediate. The adsorption strength of *OCHCH2OH intermediate on the Cu atoms via the O−Cu−C configuration can affect the selectivity of the C2 products as the cleavage of the Cu−O/Cu−C bonds determines the ethanol/ethylene pathway. The S−N−Cu structure weakens the Cu−O bond, thereby promoting the production of ethanol. This work provides a novel approach to fine‐tune the surrounding microenvironment of metal atoms on carbon nitride for highly effective photocatalytic conversion of CO2 to ethanol.