Non-Noble-Metal Catalyst of Cu/g‑C₃N₄ for Efficient Photocatalytic Hydrogen Evolution

Developing high-efficiency, stable, and low-cost catalysts is essential for water splitting to generate hydrogen. Herein, an abundant material, g-C₃N₄ nanosheet, modified with a moderate amount of Cu atoms to form a special Cu-N₃ structure exhibits excellent performance of photocatalytic hydrogen generation under visible light illumination. The structure of Cu-N₃ is formed through Cu-atom-substituted C atoms in g-C₃N₄. X-ray absorption fine structure spectroscopy (XAFS) was employed to confirm the Cu coordination and the special structure of Cu-N₃. Doping of Cu atoms not only regulates the energy band structure but also enhances the visible light absorption of g-C₃N₄ as confirmed by the UV–vis diffuse reflectance spectroscopy and Mott–Schottky test, and significantly improves the separation and transfer of photogenerated charges confirmed by the electrochemical test. Therefore, the catalyst exhibits a superior photocatalytic hydrogen production rate of 3774.35 μmol·g^–1·h^–1 and an apparent quantum efficiency (AQE) of 1.34% under visible light illumination (at 427 nm), which are both more than 3 times those of pure g-C₃N₄ nanosheets (1116.07 μmol·g^–1·h^–1 and 0.40%, respectively).