Constructing a 2D/2D heterojunction of MoSe2/ZnIn2S4 nanosheets for enhanced photocatalytic hydrogen evolution

Abstract

The low separation efficiency and high recombination of photogenerated charge carriers are the main challenges in the development of effective photocatalytic materials. The construction of two-dimensional (2D) nanosheet heterostructures with a co-catalyst would accelerate the photogenerated charge transfer and increase the number of active sites for H₂ evolution, which may be an effective strategy to improve charge separation efficiency and reduce recombination. In this research, novel 2D/2D MoSe₂/ZnIn₂S₄ complex heterojunctions have been successfully synthesized by a secondary hydrothermal method. 2D ZnIn₂S₄ nanosheets were firstly prepared and then 2D MoSe₂ nanosheets were formed on the ZnIn₂S₄. As a cocatalyst, the 2D MoSe₂ nanosheets could provide abundant active sites reducing the overpotential and the activation energy for water reduction. By synergic effects, the 2D/2D heterojunction formed between MoSe₂ and ZnIn₂S₄ can provide a large and intimate contact area, which accelerates the photogenerated charge separation and transfer resulting in high photocatalytic activity. It has been demonstrated that the H₂ evolution rate using 10%MoSe₂/ZnIn₂S₄ as the catalyst is 10 times higher than that using ZnIn₂S₄ alone as the catalyst, which is 1226 μmol g⁻¹ h⁻¹ and 116 μmol g⁻¹ h⁻¹, respectively, in water splitting under visible light irradiation. This work provides more insights into the rational design and synthesis of 2D heterostructures by using 2D materials as co-catalysts.