Strain engineering and photocatalytic application of single-layer ReS${}_2$

We present a theoretical study on the electronic, dynamical, and photocatalytic properties of single-layer ReS${}_2$ under uniaxial and shear strains. The single-layer ReS${}_2$ shows strong anisotropic responses to straining. It remains dynamically stable for a wide range of $x$-axial strain, but becomes unstable for 2% $y$-axial compressive strain. The single-layer ReS${}_2$ is calculated to be an indirect bandgap semiconductor, and there is an indirect$-$direct bandgap transition under 1$-$5% $x$-axial tensile straining. The single-layer ReS${}_2$ is predicted incapable of catalyzing the water oxidation reaction. However, 1$-$5% $y$-axial tensile strain can enable the single-layer ReS${}_2$ for overall photocatalytic water splitting. Besides, the single-layer ReS${}_2$ can also catalyze the overall water splitting and be most efficient under acidic water solutions with pH=3.8.