First-principles study on the electronic properties of GeC/BSe van der Waals heterostructure: A direct Z-scheme photocatalyst for overall water splitting

Abstract

Constructing two-dimensional (2D) van der Waals (vdW) heterostructures is a promising strategy to improve the photocatalytic efficiency of a single 2D material and has attracted wide attention. Here, the electronic structures, optical properties, and photocatalytic mechanism of the 2D GeC/BSe vdW heterostructure are investigated by first-principles calculations. It is demonstrated that the GeC/BSe heterostructure is comparatively very stable and possesses a staggered band alignment configuration. An intrinsic built-in electric field from the GeC layer to the BSe layer would be established at the interface, allowing the formation of Z-scheme charge transfer mode in the GeC/BSe heterostructure. Furthermore, its band edges exactly straddle the water redox potentials; overall water splitting can thus be expected. The GeC/BSe heterostructure also has a good light absorption coefficient with the magnitude order of ${10}^{5}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$. Moreover, it is proposed that the adoption of tensile strain can further promote the optical absorptions in the visible light range because of the favorable modulation in the bandgap, which benefits the photocatalytic reaction. Finally, the excellent abilities of ${\mathrm{H}}_{2}\mathrm{O}$ adsorption and ${\mathrm{H}}_{2}$ desorption are shown in the GeC/BSe heterostructure. These features make the GeC/BSe heterostructure promising for application in photocatalysis for water splitting.