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

Abstract

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.

Anisotropic 2D SiAs for High‐Performance UV–Visible Photodetectors

“…This bandgap is in good agreement with the calculated bandgap (2.3-2.4 eV) for the monolayer using HSE-06 basis sets. [19][20][21]25] Since Raman spectroscopy can provide information about the in-plane anisotropic phonon vibration of SiAs, we performed ARPRS measurements as described in the schematic diagram of Figure 2a. The incident light (514.5 nm) was polarized using a linear polarizer.…”

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to their low-symmetry monoclinic or orthorhombic unit cells. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] Their inplane anisotropic structures originate from unequal bond angles and strengths along the two in-plane crystallographic axes (i.e., the armchair and zigzag directions). In the past few years, much attention has been focused on the quantum-confinement effect on bandgap structures.

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“…The monolayers have wide bandgaps (2-3 eV) that are much larger compared to the bulk by at least 1 eV. [16][17][18][19][20][21][22][23][24][25] The widened bandgap allows efficient collection of visible light photons, and the bandgap positions are appropriate for visible-light-driven water splitting. The anisotropic absorption spectrum of GeAs, GeAs 2 , and SiAs 2 has been predicted by calculations.…”

“…[27][28][29][30][31][32]34] For the SiAs monolayer (monoclinic phase), the calculations predicted the direct bandgap semiconductor. [16,21,23,25] Moreover, the smaller carrier effective masses than those of Ge series promise excellent transport properties with fast repose time. [20,21] The SiAs is also anticipated to have highly anisotropic transport properties due to large different in the effective masses along the two perpendicular directions on the basal plane.…”

Intrinsic defect engineered Janus MoSSe sheet as a promising photocatalyst for water splitting

“…25 And Gao et al also proposed eight IV-V compound materials showing excellent photocatalysts for water splitting reactions with high efficiency of visible light. 26 Recently, Lu et al have grown a Janus monolayer of transition metal dichalcogenides named MoSSe through breaking the out-of-plane structural symmetry of the single layer MoS 2 . 27 Janus MoSSe is structurally viewed as MoS 2 with all of S atoms on one side replaced by Se atoms, and exhibits an electronic structure similar to that of MoS 2 .…”