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).