Breaking symmetry of carbon nitride skeleton by embedding pyridine ring to promote photocatalytic performance

Breaking symmetry of polymeric carbon nitride (CN) skeleton by heteroatomic substitution can induce in-plane polar electric field, thus promoting the migration and separation of photoexcited charge carriers. Herein, a carbon-doped CN (pyCN) by embedding pyridine ring was prepared through a skeleton modification strategy. Owing to the n → π* electron transition and the formed in-plane polar electric field, the obtained pyCN displayed obvious extended optical absorption and photoinduced charge migration efficiency in comparison with pure CN. The optimized photocatalytic H2 evolution rate over pyCN reached 242.9 μmol·h−1, which is 6 times of that over pure CN with TEOA as a sacrifice. Additionally, the wavelength for H2 evolution over pyCN extends to 550 nm while that is 450 nm over pure CN, demonstrating an improved efficiency of sunlight utilization after skeleton modification. In addition, pyCN showed synergistic oxidation of bisphenol A (BPA) during hydrogen generation under visible light. The conversion efficiency of BPA reached 18.7 % in 24 h according to the external standard analysis. This work provides an efficient approach for enhancing optical absorption and inhibiting photoexcited charge recombination for higher photocatalytic performance and wilder applications.