Insight into enhanced photocatalytic properties of a type-II MoS2/ZnO heterostructure and tuning its properties and interfacial charge transfer by strain

Abstract

The vertical stacking of two-dimensional (2D) materials to fabricate van der Waals (vdW) heterostructures is an efficacious method for efficient photocatalysts. Herein, a vdW heterostructure, MoS₂/ZnO, with six different stacking patterns is thoroughly scrutinized by exploring its structural, electronic and photocatalytic properties for their use in photocatalysis. Among the six stacking patterns, conf-5 has the most stable structure owing to its lowest interlayer binding energy, which is further considered for the detailed study of the electronic and photocatalytic properties with an applied in-plane and vertical strain. The heterostructure exhibits a type-II band alignment, where MoS₂ and ZnO are located at the conduction band minima (CBM) and valence band maxima (VBM), respectively. Moreover, enhancements in carrier mobility were observed as 820 cm² V⁻¹ s⁻¹ and 200 cm² V⁻¹ s⁻¹ for electrons and holes, respectively, along the zig-zag direction of the heterostructure. The large conduction and valence band offset values induced a high built-in potential at the interface, which reduced the carrier recombination rate by efficiently separating the charge carriers. The calculated hydrogen adsorption free energy on the S top was −0.03 eV, closer to the ideal value. Interestingly, the 1% tensile strain-induced heterostructure is more suitable for overall water-splitting (WS) owing to its band edges being properly aligned and near to water redox potentials (WRP). In addition, the effect of biaxial tensile strain enhances the visible light absorption of the heterostructure. Our findings proposed that the MoS₂/ZnO heterostructure is an excellent photocatalyst for WS applications.