Electronic Structure Modulation of Bimetallic Sulfides for Efficient Sacrificial-Agent-Free Photocatalytic H2 Evolution

The consumption of sacrificial agents is inevitable to improve the separation and utilization of electron–hole pairs in photocatalytic H2 evolution, which is contrary to the current vision of carbon neutrality and carbon peak. Here, bimetallic sulfides composed of highly dispersed Cu-doped ZnS composites were proposed, exhibiting an optimal H2 evolution activity of over 1569 μmol/g at 2 h (0.5 g/L catalyst) under visible light irradiation at pH = 3 with zero sacrificial agents or cocatalyst consumption, which is approximately 21 times higher than that of pure ZnS. A series of advanced characterizations indicate that the Cu atoms have been doped into the ZnS lattices, exposing a CuS (101) facet on the surface of the ZnS (111) facet. This results in a narrower energy bandgap (Eg = 2.6 eV) in optimal bimetallic sulfides (ZCS0.1), which is beneficial for absorbing more visible light. In particular, the introduction of Cu induces a nonequilibrium charge distribution on the ZCS0.1 surface, thereby boosting the separation and migration of photoinduced carriers. According to theory calculation (DFT) results, the hydrogen adsorption free energy (ΔGH) of ZCS0.1 is reduced than that of pure ZnS, facilitating the efficient reduction of H+/H2O around the electron accumulation regions and oxidation of H2O around the photogenerated hole (h+) regions. The modulation of the surface electronic structure is significant for effectively separating and utilizing photoinduced carriers under natural conditions without the consumption of sacrificial agents.