Designing Defective Crystalline Carbon Nitride to Enable Selective CO2 Photoreduction in the Gas Phase

Abstract Polymeric carbon nitrides are promising photocatalysts for CO 2 photoreduction, but still show lower activity and selectivity. Herein, the synthesis of an ordered crystalline carbon nitride is reported which is simultaneously rich in special defects, accomplished via the co‐condensation of guanidine hydrochloride and dicyandiamide under acetonitrile‐promoted solvothermal conditions. The high crystallinity boosts charge migration, and the structural terminations with cyano and carboxyl groups result in the improvement of optical absorption, the ability to store charges at the surface, and CO 2 binding. The crystalline carbon nitride with surface defect design enables the effective gas‐phase CO 2 photoreduction into hydrocarbon fuels while oxidizing water to oxygen, at a rate of 12.07 µmol h −1 g −1 and a selectivity of 91.5%, both values of which are remarkably higher than those of most previous carbon nitride photocatalysts. This study highlights the preparation of defective crystalline carbon nitride using a low‐temperature solvothermal synthesis, as well as a resultant good selectivity toward hydrocarbons in the application of gas‐phase CO 2 photoreduction in the absence of any cocatalyst or sacrificial agent.