Dramatic enhancement of the photocatalytic activity of Cd0.5Zn0.5S nanosheets via phosphorization calcination for visible-light-driven H2 evolution

Abstract

In the present work, phosphorized Cd_0.5Zn_0.5S nanosheets were prepared through a hydrothermal process followed by phosphorization calcination at 500 °C. Meanwhile, the photocatalytic activity of the as-prepared phosphorized Cd_0.5Zn_0.5S nanosheets was explored for H₂ evolution from water under visible light irradiation. The results indicate that the photocatalytic activity of the Cd_0.5Zn_0.5S nanosheets can be dramatically enhanced by phosphorization. Under optimal conditions, the H₂ evolution rate over the phosphorized Cd_0.5Zn_0.5S nanosheets is up to 22.5 mmol h⁻¹ g⁻¹, and the apparent quantum efficiency is about 4.6% at 450 nm, which is 1.3 times higher than that over the pure Cd_0.5Zn_0.5S nanosheets. Furthermore, the photocatalytic mechanism was preliminarily discussed. It is found that the aforementioned enhancement of the photocatalytic activity may be ascribed to the introduction of Zn₃P₂ clusters. Here, the Zn₃P₂ clusters serve as charge transferring sites and/or active sites, which leads to efficient separation of the photogenerated electrons and holes, fast charge transfer and a lower hydrogen overpotential.