Prominent roles of Ni(OH)2 deposited on ZnIn2S4 microspheres in efficient charge separation and photocatalytic H2 evolution

Abstract

In this work, Ni(OH)₂-deposited ZnIn₂S₄ microspheres (Ni(OH)₂/ZnIn₂S₄) were fabricated using a hydrothermal process, followed by a facile in situ precipitation method. It was demonstrated that the deposition of Ni(OH)₂ on ZnIn₂S₄ effectively promotes the separation of charges photogenerated over ZnIn₂S₄, and significantly enhances photocatalytic H₂ evolution. The optimum rate of the photocatalytic H₂ evolution over the 6% Ni(OH)₂/ZnIn₂S₄ composite reaches 4.43 mmol g⁻¹ h⁻¹, which is 21.1 times higher than that of the pure ZnIn₂S₄. Based on various characterization results and Au photo-deposition on the composite, it was proposed that the capture of the photogenerated holes by the deposited Ni(OH)₂ would be responsible for the efficient charge separation, which allows more photogenerated electrons to be left on the ZnIn₂S₄ for the reduction of H⁺ to H₂ with a higher rate.