Oxygen Doping in Graphitic Carbon Nitride for Enhanced Photocatalytic Hydrogen Evolution

The incorporation of oxygenic groups could remarkably enhance the light absorption and charge separation of graphitic carbon nitride (g‐C 3 N 4 ). The intrinsic role of oxygenic species on photocatalytic activity in g‐C 3 N 4 has been intensively studied, but it is still not fully explored. Herein, the essential relationships between oxygenic functionalities and the catalytic performance are revealed. Results demonstrate that C−O−C functionality as an electron trap could help to increase the resistance of conduction transfer ( R ct ) by limiting electrons transfer in CNx. In contrast, N−C−O functionality between different tri‐ s ‐triazine unites could promote the electrons transfer, leading to a reduced R ct in CNx. The best H 2 production rate (3.70 mmol h −1  g −1 , 12.76‐fold higher than that of CN) is obtained over CN3, because of the highest N−C−O ratio ( r N−C−O ). The apparent quantum efficiency (AQE) of CN3 at 405 nm, 420 nm, 450 nm, 500 nm and 550 nm is 33.90 %, 20.88 %, 8.25 %, 3.66 % and 1.01 %, respectively.