Ultrafast NaN3-deflagration induced nitrogen vacancy-enriched g-C3N4 for tailoring band structures and enhanced photocatalytic performance

Vacancy defect engineering is capable of manipulating electronic structure of metal-free photocatalysts such as graphitic carbon nitride for significantly enhancing catalytic activities. Here, we report a one-step in-situ doping strategy to synthesize nitrogen-vacancy-enriched g-C3N4 (DCN) through NaN3-deflagration. Small addition of NaN3 endows ultrafast deflagration within only 5 s during polycondensation of dicyanodiamine, where partial N-atoms suffer from reduction instantaneously by Na-nanoclusters and leaving remarkable numbers of nitrogen vacancies during the formation of g-C3N4. Such high content of two-coordinated nitrogen vacancy benefits dramatically improving optical absorption and narrowed band gap of g-C3N4, which is supported by both experimental and density functional theory (DFT) calculations. The resulting defective g-C3N4 products demonstrate high photocatalytic performances in both photocurrent response and organic pollutant degradation, which is significantly superior to that of pristine g-C3N4. The deflagration-assisted defect engineering strategy is promising for constructing other high-performance metal-free photocatalysts.