Construction of CoS2/Zn0.5Cd0.5S S-Scheme Heterojunction for Enhancing H2 Evolution Activity Under Visible Light

In the field of photocatalysis, building a heterojunction is an effective way to promote electron transfer and enhance the reducibility of electrons. Herein, the S-scheme heterojunction photocatalyst (CoS₂/Zn_0.5Cd_0.5S) of CoS₂ nanospheres modified Zn_0.5Cd_0.5S solid solution was synthesized and studied. The H₂ evolution rate of the composite catalyst reached 25.15 mmol g⁻¹ h⁻¹, which was 3.26 times that of single Zn_0.5Cd_0.5S, whereas pure CoS₂ showed almost no hydrogen production activity. Moreover, CoS₂/Zn_0.5Cd_0.5S had excellent stability and the hydrogen production rate after six cycles of experiments only dropped by 6.19 %. In addition, photoluminescence spectroscopy and photoelectrochemical experiments had effectively proved that the photogenerated carrier transfer rate of CoS₂/Zn_0.5Cd_0.5S was better than CoS₂ or Zn_0.5Cd_0.5S single catalyst. In this study, the synthesized CoS₂ and Zn_0.5Cd_0.5S were both n-type semiconductors. After close contact, they followed an S-scheme heterojunction electron transfer mechanism, which not only promoted the separation of their respective holes and electrons, but also retained a stronger reduction potential, thus promoting the reduction of H⁺ protons in photocatalytic experiments. In short, this work provided a new basis for the construction of S-scheme heterojunction in addition to being used for photocatalytic hydrogen production.