Effect of amino acids on supramolecular assembly-derived carbon nitride with enhanced photocatalytic hydrogen evolution

Structure engineering of carbon nitride via supramolecular self-assembly is an effective way to improve the photocatalytic performance. This work has conducted an investigation into the effect of different amino acids on the structure and property of target carbon nitrides, attempting to reveal the role of their terminal groups on the supramolecular self-assembly behavior, and the origin of enhanced photocatalytic performance, i.e. L-glutamic acid (carboxyl-termination), L-arginine (guanidyl-termination) and L-glutamine (amide-termination). The experimental results showed that the employment of carboxyl-/guanidyl-terminated amino acids endowed the as-synthesized carbon nitrides with a superior PHE efficiency to amide-terminated amino acid. Based on the analysis, we ascribed the enhanced photocatalytic performance to the amidation during supramolecular assembly, leading to a carbonyl grafted, mesopore enriched micro-tubular structure for the finally synthesized products. This feature favors the increased active sites, shortened carriers' migration paths. Specifically, the optimal amino acid-derived carbon nitride exhibited a 10.6-fold improvement in PHE rate, in comparison with pristine carbon nitride.