Fabrication of Zn-doped Cu2O for auxiliary graphdiyne to enhance photocatalytic H2 evolution performance

Abstract

Graphdiyne (GDY) is widely used in photocatalysis due to its large specific surface area, high porosity and good stability. In this study, GDY was prepared by ball-milling-assisted alkyne-negative method, and GDY/Zn-Cu2O S-scheme heterojunction catalysts were constructed by introducing Zn-doped Cu2O into it through low-temperature mixing. The modified composite catalysts showed hydrogen evolution performance reached 213.65 μmol after 5 h of visible light irradiation, which was 142.4, 82.2 and 8.1 times than that of Cu2O, Zn-Cu2O and GDY, respectively. The large specific surface area of GDY provided abundant active sites to promote surface kinetics. Zinc doping adjusted the energy band structure of Cu2O and improved the light absorption efficiency of the catalysts. The S-scheme heterojunction established between Zn-Cu2O and GDY greatly facilitated the separation and transport of photogenerated carriers, which was the dominant factor for the improvement of hydrogen evolution performance. A possible mechanism is proposed and analyzed by combining ultraviolet photoelectron spectroscopy (UPS), valence band XPS (VB-XPS), in-situ irradiated X-ray photoelectron spectroscopy (In-situ XPS) and density functional theory (DFT) results. This work provides a new insight into the doping and construction strategies of GDY-based S-scheme heterojunction.