One-step synthesis of nitrogen-defective graphitic carbon nitride for improving photocatalytic hydrogen evolution

Defects are significant for graphitic carbon nitride (g-C₃N₄, CN) in photocatalytic applications. Defective CN not only accelerate charge separation but also extend spectral response. Engineering carbon or nitrogen defects in CN has been achieved by variety of strategies, but it is still a long-term interest to develop a simple and controllable route for engineering defects in CN. Herein, we present tuning the nitrogen defects in CN by either changing the heating rate or prolonging the pyrolysis time during polymerization melamine sulfate. It was found that either lower heating rate or longer pyrolysis time lead to the formation of more N vacancies and suspended terminal amino. As a result, an optimal photocatalytic H₂ yield rate (λ > 420 nm) of 905 μmol g^-1 h^-1 was reached, which was 2 times higher than that of CN prepared with a heating rate of 1 °C/min and pyrolysis at 600 °C for 4 h.