Uracil-mediated supramolecular assembly for C-enriched porous carbon nitrides with enhanced photocatalytic hydrogen evolution

The substitution of C for N in graphitic carbon nitride (g-C₃N₄) can promote pi-electron availability and increase photocatalytic activity, but the low specific surface area still limits its performance. Herein, porous C-doped g-C₃N₄ was prepared by the uracil-mediated supramolecular assembly of melamine and cyanuric acid. The as-prepared catalyst exhibited a high photocatalytic hydrogen evolution rate of 2352 μ mol g^-1 h^-1 under visible light irradiation (λ ≥ 420 nm), which was 28 times that of g-C₃N₄ (83 μ mol g^-1 h^-1), due to the porous architecture and C-doping effect. The porous architecture endowed the catalyst with a large specific surface area (79.4 m(2) g^-1) and great light utilization efficiency in the visible light region between 500 and 750 nm. In addition, C-doping modified the energy band structure of g-C₃N₄ to a narrow band gap (from 2.92 eV to 2.78 eV) and enhanced the separation efficiency of photogenerated carriers. (authors)