MoS₂ and MoSSe Based van der Waals Heterostructures as an Emerging Direct Z-scheme Photocatalysts

MoS₂ monolayer, a prototypical transition metal dichalcogenide (TMD), with high carrier mobility and apt optical properties have often been used in photocatalysis. Janus (MoSSe) too follows the same. However, their usage is limited by the carrier (e^--h⁺) recombination, making it imperative to examine their bilayer van der Waals heterostructure (vdW HTS), where the spatial separation of e^--h⁺ on two layers reduce recombination. The design of bilayer vdW HTSs here, consists of TMDs (HS₂, ZrS₂, TiS₂, WS₂) and transition metal oxides (TMOs) (HfO₂, T-SnO₂, T-PtO₂). The present work displays curiosity in their Z-scheme photocatalytic capability, where faster interlayer e^--h⁺ recombination is required for efficient charge separation. We have performed first-principles based calculations under the framework of (hybrid) density functional theory (DFT) and many-body perturbation theory (GW approximation), to obtain the band edge levels and optical spectra, respectively. The comparative study of vdW HTSs and the constituent monolayers, have been undertaken by analyzing their electrostatic potential, work function and e^--h⁺ recombination. Finally, with the promising optical response, we find MoSSe/HfS₂, MoSSe/TiS₂, MoS₂ /T-SnO₂, MoS₂ /ZrS₂ and MoSSe/ZrS₂ as probable Z-scheme photocatalysts.