Structural Distortion of g-C₃N₄ Induced by a Schiff Base Reaction for Efficient Photocatalytic H₂ Evolution

Photocatalytic H₂ evolution by water splitting is a promising approach to address the challenges of environmental pollution and energy scarcity. Graphitic carbon nitride (g-C₃N₄) has emerged as a star photocatalyst because of its numerous advantages. To address the limitations of traditional g-C₃N₄, namely its inadequate visible light response and rapid recombination of photogenerated carriers, we employed a schiff base reaction to synthesize -C=N- doped g-C₃N₄. The introduction of -C=N- groups at the bridging nitrogen sites induced structural distortion in g-C₃N₄, facilitating n-π* electronic transitions from the lone pair electrons of nitrogen atom and extending light absorption up to 600 nm. Moreover, the presence of heterogeneous π-conjugated electron distribution effectively traps photogenerated electrons and enhances charge carrier separation. Benefiting from its expanded spectral response range, unique electronic properties, increased specific surface area, the doped g-C₃N₄ exhibited outstanding photocatalytic H₂ evolution performance of 1050.13 μmol/g/h. The value was 5.9 times greater than the pristine g-C₃N₄.