The impact of benzene ring embedding on the performance of carbon nitride for photocatalytic hydrogen

Forming local micro-π conjugate connection units in the structure of carbon nitride (CN) at the interface to capture photo-generated electrons can reduce the band gap and simultaneously facilitate the charge transfer. Herein, the H₃BTC/CN composites with benzene ring embedded structure were prepared through the acid-base reaction between H₃BTC and melamine. The precursor reaction method effectively enhanced the dispersity and utilization efficiency of modification molecule. The introduced benzene ring of H₃BTC increased the double bonds of π conjugated system, decreased the band gap and widened the response range of visible light. At the same time, benzene ring acted as the electron acceptor to capture photo-generated electrons and promote the effective separation of photo-generated charge carriers. The optimal catalyst, 7.5 wt% H₃BTC/CN showed an enhanced photocatalytic hydrogen evolution rate of 301 μmol g^-1h⁻¹, which was 21.8 times higher than that of pure CN. The work manifested the positive impact of benzene ring embedding on CN structure and photocatalytic performance, which proposed a new strategy for the design and preparation of high-efficiency photocatalyst.