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Abstract
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Following the successful synthesis of NaSnAs in 2021, in the present study, a series of two-dimensional SnXY monolayers with X = P, As, Sb, and Y = H, CH3 are theoretically predicted. First principle calculations are performed to investigate the structural, electronic, mechanical, and optical properties of these materials. The results predict desirable dynamical and thermal stabilities with high mechanical strength for considered systems. It is found that all SnXY monolayers are semiconductors with a direct band-gap lying in the visible region. The values of band-gap decrease as the size of the X atom increases which indicates the dominant contribution of the X atom in the band edge positions. Employing biaxial strain leads to narrowing the electronic band-gaps and suggests a strain-tuneable band-gap character in these structures. The results also highlight high carrier mobilities along the SnXY monolayers. By virtue of possessing suitably large band gaps, well-matched band offsets, robust optical absorption within the visible spectrum, high carrier mobility, and moderate exciton binding energies, these systems are poised as prospective candidates for applications in photocatalysis. Accordingly, we have also explored the photocatalytic activity of SnPH and SnAsH monolayers toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The calculated reaction free energy profiles demonstrate the exceptional performance of these systems in facilitating overall water splitting. This study provides a comprehensive vision of novel 2D SnXY monolayers and a new outlook for designing superior photocatalysts for water splitting.
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