Theoretical perspective of photocatalytic properties of single-layer SnS2

We present a first-principles study of the photocatalytic properties of single-layer SnS${}_{2}$. First, we calculate the formation energy and the phonon spectrum, verifying static and dynamical stability, respectively. In addition, our calculated energy of solvation suggests that single-layer SnS${}_{2}$ is stable in aqueous solution. Next, by solving the Bethe-Salpeter equation, we obtain an optical band gap of 2.75 eV, consistent with the measured optical band gap. The resulting exciton binding energy of 0.41 eV is consistent with the Mott-Wannier model. Finally, by aligning the band edges with the redox potentials of water, we find that a bias potential of at least 0.9 V is required to drive the hydrogen evolution and that compressive strains can reduce this bias potential.