Hydrophobicity-aerophilicity effect boosting efficient CO2 photoreduction in graphitic carbon nitride modified with fluorine-containing groups

Inspired by the lotus leaf effect, constructing a hydrophobic surface to endow photocatalysts with underwater aerophilicity, is an effective measure to improve the accessibility of CO 2 on the catalyst surface during CO 2 photoreduction in the liquid phase. Unfortunately, the aerophilic advantages of the material cannot be fully exploited with the extremely low solubility of CO 2 in water. Thus, applying the “hydrophobicity-aerophilicity effect” to gaseous CO 2 atmosphere, that is, proving that the hydrophobic material has aerophilic effect in air, has become a challenge. Herein, a hydrophobic graphitic carbon nitride (g-C 3 N 4 ) photocatalyst modified by CF 2 groups (CF 2 -TCN) is developed to enhance the aerophilicity of the CF 2 -TCN in air. A theoretical model of the gas-phase “hydrophobicity-aerophilicity effect” and the corresponding theoretical support are presented. Experimental characterizations demonstrate that the grafted CF 2 groups create a hydrophobic surface for CF 2 -TCN, acting as a gas transport layer and enhancing the aerophilicity of CF 2 -TCN. Theoretical calculations further explain that the strong electronegativity of F atoms in CF 2 groups affects the electron cloud distribution of g-C 3 N 4 , facilitating the adsorption and activation of CO 2 by CF 2 -TCN. Furthermore, the electron-withdrawing effect of F atoms efficiently extracts electrons, accelerating the intramolecular charge transfer. Benefiting from enhanced aerophilicity and improved electron transfer, the output of CO and CH 4 by CF 2 -TCN are 30.94 and 7.39 μmol·h −1 ·g −1 without any sacrificial agents, far exceeding that of bulk g-C 3 N 4 (BCN) by 5.54 and 18.95 times, respectively.