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

Abstract

The consumption of sacrificial agents is inevitable to improve the separation and utilization of electron−hole pairs in photocatalytic H 2 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 H 2 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 (E g = 2.6 eV) in optimal bimetallic sulfides (ZCS 0.1 ), which is beneficial for absorbing more visible light. In particular, the introduction of Cu induces a nonequilibrium charge distribution on the ZCS 0.1 surface, thereby boosting the separation and migration of photoinduced carriers. According to theory calculation (DFT) results, the hydrogen adsorption free energy (ΔG H ) of ZCS 0.1 is reduced than that of pure ZnS, facilitating the efficient reduction of H + /H 2 O around the electron accumulation regions and oxidation of H 2 O 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.

TiO2-Based Photocatalytic Coatings on Glass Substrates for Environmental Applications

“…Semiconductor-based photocatalysis is a green and sustainable advanced oxidation process (AOP) that can directly convert green solar energy into chemical energy [4][5][6]. Therefore, semiconductor photocatalysis has been widely used in the environmental and energy fields [7][8][9][10][11][12][13]. Various semiconductor materials have been developed as photocatalysts, such as TiO 2 , g-C 3 N 4 , ZnO, Bi-based, and Ag-based materials [14][15][16][17][18][19][20][21][22][23].…”