Precise defect engineering g-C3N4 fabrication to improve hydrogen production performance

Designing a reasonable defect structure in carbon nitride could effectively suppress the recombination of charges and holes. However, there was a lack of precise strategies for planning defect engineering. To address this, a multi-step strategy involving secondary thermal condensation and sodium assistance was successfully developed. This strategy synthesized -NHx vacancies and cyanamide defects co-modified g-C3N4 (NCMCN). By adjusting the bulk g-C3N4 (MCN), the two defect structures obtained enhanced the light response ability, increased the specific surface area, and reduced the band gap. These improvements were supported by experimental results and density functional theory (DFT) calculations. Consequently, NCMCN demonstrated outstanding photocatalytic performance compared to both pristine MCN and nitrogen vacancy-modified NVMCN. Notably, the Hydrogen Evolution Reaction (HER) results of NCMCN were 10.65 times higher than those of MCN.