WP modified S-scheme Zn0.5Cd0.5S/WO3 for efficient photocatalytic hydrogen production

Abstract

In this work, a noble metal free photocatalyst WP/Zn_0.5Cd_0.5S/WO₃ (WZP) was prepared for the first time by simple hydrothermal and physical mixing methods. When the mass ratio of WP : Zn_0.5Cd_0.5S : WO₃ reaches 0.4 : 1 : 0.4, the hydrogen production could reach 26 262 μmol within 5 h, which is about 5.04 times higher compared to pure Zn_0.5Cd_0.5S. The WZP composite not only has good stability but also excellent apparent quantum efficiency (6.19%). The band gaps and conduction band positions of Zn_0.5Cd_0.5S and WO₃ were identified from the UV-vis DRS and Mott–Schottky results, and the existence of an S-scheme between them was preliminarily determined. In addition to this, the existence of the S-scheme was further confirmed by the analysis of hydrogen evolution test results. A series of characterization results such as UV-vis DRS, PL, TRPL and electrochemical results showed that the addition of WP greatly improved the absorption and response of the composite to visible light. Based on the above experimental results, the possible hydrogen evolution mechanism of the WZP photocatalyst was proposed. It is believed that this work marks an important step toward developing high-performance and low-cost photocatalytic materials for H₂ evolution.