Strain Modulated Electronic and Photocatalytic Properties of MoS2/WS2 Heterostructure: A DFT Study

Abstract

Solar energy-driven hydrogen generation through the water-splitting (WS) method is an efficient approach to conquer the worldwide energy shortage in the near future and environmental pollution by employing a suitable semiconductor photocatalyst. Herein, structural, electronic, and photocatalytic properties of MoS2/WS2 heterobilayer are thoroughly inspected with biaxial strain for their use in WS applications. Furthermore, among the six considered stacking patterns of the heterostructure (HS), conf-1 has the most stable structure due to its lowermost interlayer binding energy of −18.07 meV/Å2. In addition, MoS2/WS2 HS shows type II band alignments, where MoS2 contributes to the conduction band minima (CBM), and the WS2 monolayer is located at valence band maxima (VBM) positions, respectively, in the HS. Moreover, owing to the smaller effective mass values of the HS than to the constituent monolayers, MoS2/WS2 HS has excellent carrier mobility, which further suggests faster migration of charge carriers and a lower recombination rate during the WS process. An enhanced visible light absorption intensity of 8.3 × 105 cm–1 has been observed for the HS rather than the MoS2 (6.33 × 105 cm–1) and WS2 (7.51 × 105 cm–1) monolayers. The HSs under the biaxial tensile strain of 1% and compressive strain up to 4% are attended suitable CBM and VBM positions with water reduction (WRP) and oxidation potentials (WOP) that are appropriate for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Moreover, under tensile strain, the absorption edges of HS are moderately red-shifted, which makes it as a potential candidate for solar energy harvesting. Our findings open a new research interest in exploring these kinds of 2D vdW HSs experimentally for a WS mechanism, and modulation of their activity can be done by external strain.