Interface engineering of a noble-metal-free 2D–2D MoS2/Cu-ZnIn2S4 photocatalyst for enhanced photocatalytic H2 production

Abstract

Accelerating the charge separation of semiconductor photocatalysts remains a great challenge to develop highly efficient solar-to-H₂ conversion systems. Here, 2D Cu²⁺-doped ZnIn₂S₄ (Cu-ZnIn₂S₄) nanosheets modified with 2D MoS₂ are designed and prepared via solution chemical routes. Detailed characterization reveals that the specially designed unique 2D–2D structure is critical to the high photocatalytic performance for solar H₂ generation. Benefiting from the presence of a large 2D nanojunction in the 2D–2D photocatalyst, the MoS₂/Cu-ZnIn₂S₄ has an increased contact surface area for charge transfer. The improved charge separation is demonstrated by the significant enhancement of photocurrent responses. It is found that the 2D–2D MoS₂/Cu-ZnIn₂S₄ photocatalyst at a 6 wt% MoS₂ loading amount exerts a 5463 μmol h⁻¹ g⁻¹ H₂-evolution rate under visible light irradiation (λ > 420 nm) with an apparent quantum yield of 13.6% at wavelength λ = 420 nm in 0.1 M ascorbic acid aqueous solution. This activity far exceeds those of noble metal (such as Pt, Ru, Pd or Au) loaded-Cu-ZnIn₂S₄ photocatalysts. The results demonstrate that the construction of a 2D nanojunction is a promising strategy to accelerate charge separation and enhance the photocatalytic performance of semiconductor photocatalysts for solar H₂ generation.