Porous g-C₃N₄ with simultaneous carbon doping for photocatalytic water treatment and splitting

Porous g-C 3 N 4 , synthesised from urea and gelatin as a template, achieves extended photon absorption in the visible region and rapid photogenerated charge transfer. Gelatin increased disorder and interlayer spacing of g-C 3 N 4 layers, transforming the stacked g-C 3 N 4 nanosheets into a thin nanosheet layer with a C/N ratio of 0.75. Porous g-C 3 N 4 achieved 55% of methylene blue photodegradation and 15 µmol/g hydrogen production from water splitting. However, carbon-doped g-C 3 N 4 was formed at 5% gelatin, with rod-like nanosheets and disordered triazine rings. Carbon dopant expands the d -spacing of g-C 3 N 4 from 0.320 nm to 0.354 nm, narrows the band gap energy of 2.57 eV and conducts the delocalized electron for fast charge separation. Despite 70% methylene blue photodegradation, carbon is a poor water reduction catalyst, inhibiting hydrogen production due to the accumulation of electrons on the conduction band.