N-doped graphitic carbon-incorporated g-C₃N₄ for remarkably enhanced photocatalytic H₂ evolution under visible light

Described herein is a facile one-pot strategy to synthesize N-doped graphitic carbon-incorporated g-C₃N₄ by adding slight amount of citric acid into urea as the precursor during thermal polymerization. The obtained materials retained the original framework of g-C₃N₄ and show remarkably enhanced visible light harvesting and promoted photo-excited charge carrier separation and transfer. The high-resolution N 1s spectrum of XPS showed a graphitic N peak, which could be attributed to N-doped graphitic carbon. In addition to the common-recognized light harvesting enhancement and charge carrier recombination inhibition, the incorporation of N-doped graphitic carbon into the planar framework of g-C₃N₄ is suggested to result in extended and delocalized π-conjugated system of this copolymer, thus greatly elevating the photocatalytic performance for H₂ evolution by water splitting under visible light. The H₂ evolution rate on N-doped graphitic carbon-incorporated g-C₃N₄ reached 64 μmol h^-1, which is almost 4.3 times the rate on pure g-C₃N₄. This approach may provide a promising route for rational design of high performance, cost-effective and metal-free photocatalysts.