A strategy for integrating transition metal-complex cocatalyst onto g-C3N4 to enable efficient photocatalytic hydrogen evolution

Achieving efficient and stable solar-to-hydrogen conversion is of great significance to the sustainable development of global energy. Herein, we report a novel strategy for metal functionalization via in-situ construction of metal coordination sites in graphitic carbon nitride (CN), in which pyrimidinone derivative ligands are incorporated onto CN framework through one-step vapor diffusion process, and then transition metal ions (such as Ni, Cu, Co) are covalently immobilized by strong coordination interaction. The coordination-introduced metal ions not only serve as catalytic reaction sites, but also improve the utilization of visible light through the metal ion to ligand charge transfer (MLCT) mechanism. Specially, the strong interaction between metal ion and ligand promotes charge separation by expanding the pi-conjugated delocalization system of CN, which makes it possible to continuously generate hydrogen without noble metals. The optimal sample Ni/DBM(0.12%)-CN shows a hydrogen evolution rate of 68.6 mu mol h-1 (lambda >= 420 nm) and a remarkable quantum conversion efficiency of 5.57% under irradiation of the light with wavelength of 450 nm. The mechanism of high-activity hydrogen production was studied through both experiments and theoretical calculations. This study provides a new strategy for designing cost-effective CN photocatalyst with alternative metal coordination sites for efficient visible light utilization.

Automated summary

This study presents a novel strategy for achieving efficient and stable solar-to-hydrogen conversion through metal coordination sites in graphitic carbon nitride, improving visible light utilization. The research investigates the methods and mechanisms of metal-functionalized CN materials, providing a new approach for designing cost-effective and high-activity photocatalysts.