MoSe₂/WSSe Heterostructure for Photocatalytic Water Splitting Applications: A Density Functional Theory Study

The worldwide demand for renewable energy resources is rapidly increasing to reduce environmental damage and carbon emissions. To address this, water photocatalysis emerges as a viable approach to producing green energy via hydrogen generation. In this work, we used density functional theory to examine the MoSe₂/WSSe heterostructure as a photocatalyst material for water splitting. The energy band gap was adjusted through the application of strain to enhance the photocatalytic activity, maintaining the physical separation between holes and electrons across the MoSe₂ and WSSe layers. The applied compressive strain (−2%) aligns the energy levels with the water redox potentials, enhancing the hydrogen evolution reaction (HER) and also leveraging the absorption of photons. In addition, the thermodynamic calculations indicated a low Gibbs free energy for HER, which reinforced the catalytic feasibility of the system. The findings indicate a notable enhancement in efficiency, with a 4-fold increase in it when contrasting absorber thicknesses of 1.0 and 14.0 nm, reaching 39% for a −2% strained configuration. The present results indicate that the heterojunction, when subjected to controlled strain, demonstrates exceptional electronic, optical, and catalytic characteristics for sustainable photocatalysis applications. The progress made in this area has the potential to greatly enhance the evolution of clean and renewable hydrogen generation technologies.