Mechanistic insights into the formation of N-vacancies at sp2 hybridized sites in non-metal doped g-C3N4 and its potential applications in Solar to H2 conversion and environmental remediation reactions

Abstract

Designing and constructing an efficient photocatalyst based on graphitic carbon nitride (g-C ₃ N ₄ ) nanosheets is vital for solar-to-fuel and pollutant degradation reactions. Particularly, defect engineering can effectively modify the electronic bandstructures, serve as active sites and promote the charge separation, leading to enhanced photocatalytic activity. Herein, we report dual non-metal doped g-C ₃ N ₄ (C-and O-doped g-C ₃ N ₄ ) with N-vacancies for photoredox reactions. Beneficial from dual doping and N-defects; and porous nature, the optimized g-C ₃ N ₄ photocatalyst displays extended visible light harvesting, higher specific surface area and efficient photoinduced charge separation. Consequently, as designed g-C ₃ N ₄ exhibits a higher visible light-driven photocatalytic H ₂ evolution activity of ~1850 μmol/g/h and a stable performance for 24 hours. In addition, the defect-engineered g-C ₃ N ₄ photocatalyst delivers a high tetracycline pollutant degradation efficiency of 82%. The intriguing activity can be credited to the effect of midgap states originating from the doping and N-defects, and the underlying physical mechanism for tuning the carrier dynamics is fully explored. Our work offers useful guidance for the design of two-dimensional (2D) porous nanosheets for photocatalysts and optoelectronic device applications.