Three-dimensional assemblies of nitrogen-rich polymeric carbon nitride microrods for enhanced photocatalytic hydrogen generation

Abstract

Supramolecular self-assembly is a typical non-template strategy for fabricating carbon nitride photocatalysts with tailored microstructures and optimized properties. However, current research in this field is predominantly confined to triazine-based molecules such as melamine-cyanuric acid supramolecular aggregates, which severely restricts the structural diversity and functional tunability of carbon nitride photocatalysts. Herein, we report a novel approach to synthesize nitrogen-rich polymeric carbon nitride microrods (NPCNm) via supramolecular assembly of intermediates derived from melamine and 3-amino-1,2,4triazole respectively. Owing to their high structural similarity, the two kinds of intermediates can form a longrange ordered microrod-like morphology through hydrogen bonding interactions between the nitrogen and hydrogen atoms at the edges of their molecular frameworks. This well-defined microrod architecture is robustly preserved throughout the subsequent hydrothermal treatment, freeze-drying, and calcination steps, ultimately remaining intact in the final NPCNm product. Benefiting from the synergistic effects of the microrodlike morphology and triazole-induced asymmetric structure modification, including enhanced visible light absorption and efficient charge carriers separation, NPCNm achieves a superior H2 evolution rate of 3085 μmol g -1 h -1 under visible light (λ > 420 nm), which is 23.4-fold and 11.6-fold higher than those of the carbon nitride counterparts derived from one-step calcination of melamine and 3-amino-1,2,4-triazole, respectively. This work expands the scope of supramolecular assembly for carbon nitride synthesis using atypical monomers to develop highly efficient solar-to-chemical conversion catalysts.