Regulating Local Electron Density of Cyano Sites in Graphitic Nitride Carbon by Giant Internal Electric Field for Efficient CO2 Photoreduction to Hydrocarbons.

ABSTRACT

Selective photocatalytic CO2 reduction to high-value hydrocarbons using graphitic carbon nitride (g-C3N4) polymer holds great practical significance. Herein, the cyano-functionalized g-C3N4 (CN-g-C3N4) with a high local electron density site is successfully constructed for selective CO2 photoreduction to CH4 and C2H4. Wherein the potent electron-withdrawing cyano group induces a giant internal electric field in CN-g-C3N4, significantly boosting the directional migration of photogenerated electrons and concentrating them nearby. Thereby, a high local electron density site around its cyano group is created. Moreover, this structure can also effectively promote the adsorption and activation of CO2 while firmly anchoring *CO intermediates, facilitating their subsequent hydrogenation and coupling reactions. Consequently, using H2O as a reducing agent, CN-g-C3N4 achieves efficient and selective photocatalytic CO2 reduction to CH4 and C2H4 activity, with maximum rates of 6.64 and 1.35 µmol g-1 h-1, respectively, 69.3 and 53.8 times higher than bulk g-C3N4 and g-C3N4 nanosheets. In short, this work illustrates the importance of constructing a reduction site with high local electron density for efficient and selective CO2 photoreduction to hydrocarbons.