Theoretical Insights into Two-Dimensional IV-V Compounds: Photocatalysts for the Overall Water Splitting and Nanoelectronic Applications

Two-dimensional (2D) materials have attracted enormous attention in many fields because of their appealing performances. In this contribution, we perform first-principles calculations on the photocatalytic properties of IV-V compounds, along with the design of a functional Schottky device based on a graphene/SiAs van der Waals heterostructure (vdWH). Our results indicate that eight IV-V compound materials are all excellent photocatalysts for water-splitting reactions with high efficiency of visible light, with the conduction band minimum (CBM) and valence band maximum (VBM) both involving the corresponding band-gap region. It is examined whether a weak acid environment is beneficial for the hydrogen production process. Monolayer GeAs is characterized by an excellent absorption coefficient of up to 10⁵-2 × 10⁵ cm^-1 in the visible region. The other nanostructures also have a considerable optical absorption as high as approximately half of 10⁵ cm^-1. These illustrate fascinating application prospectives for IV-V compounds in photocatalysis for water splitting under the irradiation of visible light, predicting tremendous significance in the fields of energy conversion and hydrogen production. The graphene/SiAs vdWH nanocomposite at the equilibrium state is featured for an n-type Schottky contact. External strain and electric-field applications are employed to practically present the transition for interface contact between the n- and p-type Schottky contacts or between the Schottky and ohmic contacts, which suggests appealing applications for the graphene/SiAs vdWH as a competitive candidate for functional Schottky devices and nanoelectronic materials.