Preventing the high carrier recombination rate of graphitized C 3 N 4 (GCN) is an urgent problem to be solved for its application as a photocatalyst for hydrogen production. Here, we first rationally embed the benzene ring in GCN to modify the local symmetry without changing its long-order structure. Theoretical calculation predicts that this design can change the electronic structure and promote the effective charge transfer in GCN. The benzene ring embedded GCN is successfully prepared by copolymerization using dicyandiamide and terephthalonitrile as precursors. Photoluminescence (PL) and time-resolved transient PL (TRPL) spectra confirm that the electron transfer efficiency of the benzene ring embed GCN is greatly improved. This nanomaterial displays 10.8 times higher photocatalytic hydrogen production rate than that of pristine GCN with the apparent quantum yield of 11.3% at 400 nm and 9% at 420 nm. This work provides a novel strategy for designing high-efficiency two-dimensional (2D) photocatalytic materials for water splitting.
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 H 3 BTC/CN composites with benzene ring embedded structure were prepared through the acid-base reaction between H 3 BTC and melamine. The precursor reaction method effectively enhanced the dispersity and utilization efficiency of modification molecule. The introduced benzene ring of H 3 BTC 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% H 3 BTC/CN showed an enhanced photocatalytic hydrogen evolution rate of 301 μmol g -1 h −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.
Preventing the high recombination rate of carriers in graphite-carbon nitride (GCN) is essential for hydrogen production. In this work, we break the original symmetry of GCN by embedding benzene ring for enhanced visible-light absorption and carriers transfer efficiency. The new catalyst was prepared by a condensation reaction using dicyandiamide and 5-amino-2,4,6-triiodoisophthalic acid as precursors. It shows photocatalytic hydrogen evolution rate of 690.74 μ mol g − 1 h − 1 , 9.3 times enhancement than the original GCN. This work provides a new strategy for designing efficient two-dimensional photocatalytic materials for water splitting.
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