Strain-tunable electronic and optical properties of monolayer GeSe: Promising for photocatalytic water splitting applications

In this work, we investigate the electronic and optical properties of monolayer GeSe and the possibility of enhancement the photocatalytic activities for the water splitting of monolayer GeSe through strain engineering using first-principles calculations. Our calculations indicate that monolayer GeSe is a semiconductor with a moderate indirect gap of 1.13 eV at equilibrium and we can control its band gap by biaxial strain. In the presence of biaxial strain εb, the semiconductor-metal phase transition happens at large compressive strain of -10% and the indirect-direct gap transition occurs at εb=4%. The optical spectrum of monolayer GeSe are highly anisotropic and biaxial strain can increase the absorption coefficient of monolayer GeSe up to about 6×105 cm−1. Our calculations demonstrate that monolayer GeSe possesses photocatalytic properties for water splitting at εb=5% and we can enhance its photocatalytic activity by strain. © 2019 Elsevier B.V.