Favorable photocatalytic properties of a GeS/GeS heterostructure by combining parallel and vertical electric fields: a theoretical study

Abstract

As an isoelectronic counterpart of phosphorene, single-layer germanium monosulfide (GeS) is also recognized as a potential 2D material for various optoelectronic applications. However, its photocatalytic properties suffer from a large indirect band gap and insufficient oxidation ability. Here a strategy by constructing a GeS/GeS heterostructure with different phases to ameliorate the photocatalytic performance is studied using first-principles calculations. There are parallel and vertical electric fields in black-phosphorus-phase and blue-phosphorus-phase GeS monolayers, respectively. After combination, an enhanced vertical electric field works in coordination with an in-plane electric field in the black-phosphorus-phase GeS layer to promote exposure of carriers to the surfaces or edges of different layers. And the formation of a GeS/GeS heterostructure also reduces the band gap significantly compared with individual components, expanding the light absorption range. Meanwhile, depending on different stacking orders, favorable oxidation and reduction capacities can be obtained for different photocatalytic requirements. This study proposes a new idea towards regulating the properties of GeS and improving its practicability in photocatalysis.