Ni single-atom anchored g-C3N4 via supramolecular self-assembly assisted pre-oxidation for efficient photocatalytic H2 production

To address the critical issues in nickel single-atom catalysts, including severe aggregation, poor controllability of coordination environment, and weak metal-support interaction. Herein, melamine-cyanuric acid supramolecules were used as precursors. One-step air calcination and pre-oxidation followed by argon calcination were adopted to fabricate a series of Ni single-atom decorated g-C 3 N 4 photocatalysts (CN-Ni x -I and CN-Ni x -II series). The pre-oxidation treatment significantly increased the specific surface area of the material, narrowed the band gap, and shifted the conduction band potential to a more negative direction, thereby enhancing the light-harvesting capability and the separation efficiency of photogenerated carriers. The optimal sample CN-Ni 2 -II exhibited a photocatalytic hydrogen evolution rate of 920.12 μmol h −1 g −1 , which was 4.55 times that of pure CN-II and 2.76 times that of the one-step calcined sample CN-Ni 2 -I. Mechanism analysis confirmed that the synergistic effect of the strong interfacial interaction co-constructed by C–O–Ni bonds and N coordination, the optimized band structure, and the hierarchical mesoporous structure was the core driving force for the significant improvement of its photocatalytic performance. This work provides a new path for the simple preparation and performance regulation of high-efficiency non-noble metal single-atom photocatalysts, and also offers practical reference for the interfacial engineering design of single-atom catalytic systems.