One-pot synthesis of porous graphitic carbon nitride with rich nitrogen vacancies and oxygen heteroatoms for boosting photocatalytic performance

Graphitic carbon nitride (g-C3N4), as an attractive photocatalyst, has been applied in environmental pollution control and energy conversion. However, its photocatalytic performance was plagued owing to the insufficient light absorption and poor photocarrier separation and transportation efficiencies. Herein, a porous g-C3N4 with rich nitrogen vacancies and oxygen heteroatoms was fabricated using a one-pot thermal polymerization method. Such method involves molecular homogenization of urea and ammonium bicarbonate, recrystallization of urea, and subsequent polycondensation and thermal stripping of g-C3N4 lamellas. The resultant g-C3N4 presents enriched exposed edges and interconnected open diffusion channels, and possesses abundant nitrogen vacancies and oxygen heteroatoms. This unique structure and composition of g-C3N4 contribute to exposure of active sites, migration of substrate and products, and visible light absorption in photocatalytic reactions. As expected, the design of nitrogen vacancies and oxygen heteroatoms in g-C3N4 modulated its electronic structure, thereby accelerating the photocarrier separation and further accelerating the output of •O2− radicals under light irradiation. The optimal g-C3N4 exhibited an extraordinary photodegradation performance for high concentration (C0 = 50 mg/L) of Rhodamine B. The photodegradation efficiencies are 97.5% and 99% in 90 min under visible light and sunlight irradiation, respectively. The work provides a porous g-C3N4 photocatalyst with intensified photocatalytic performance for environmental pollution control and emerging energy conversion.