A facile solvothermal recrystallization strategy engineering ultrathin g-C3N4 nanosheets for efficient boosting photocatalytic H2 evolution

Graphitic carbon nitride (g-C3N4) is a promising material for sustainable photocatalytic application, but the pristine g-C3N4 (P-C3N4) derived from thermal polymerization generally showed the relatively low photocatalytic activity. In order to obtain the desirable g-C3N4 photocatalyst, for the first time, we reported a simple solvothermal recrystallization strategy using ethanol as a green solvent for the preparation of high-performance ultrathin g-C3N4 nanosheets (labeled as 180-C3N4). The results indicated that the 180-C3N4 nanosheets with an average thickness of approximately 1.5 nm could be fabricated at an optimal solvothermal temperature of 180 °C. Comparted to P-C3N4, the resultant 180-C3N4 nanosheets possessed the faster charge mobility, enlarger specific surface area, and stronger redox capability. As a consequence, the 180-C3N4 nanosheets not only exhibited the significantly enhanced photocatalytic H2 generation performance under visible-light (λ > 420 nm) irradiation, but also showed the dramatically promoted photocatalytic H2 evolution activity both under blue (λ = 450 nm) and green (λ = 550 nm) light irradiation. This work highlights a facile “bottom-up” solvothermal recrystallization strategy for the large-scale production of highly active g-C3N4 materials, and it will play an important role in the field of clean H2 evolution and pollutant degradation by using renewable solar-driven photocatalysis technology.