A 2D ZnSe/BiOX vertical heterostructure as a promising photocatalyst for water splitting: a first-principles study

Abstract

A vertical heterostructure is an effective method for regulating the properties of 2D materials that are superior to their individual components due to the interfacial interaction. Here, 2D ZnSe/BiOX (X = Cl, Br, I) vertical heterostructures as potential photocatalysts for water splitting are systematically investigated using first-principles calculations. The results indicate that the binding strength of the heterostructure is larger than −17.6 meV Å−2, favoring its experimental realization. Furthermore, the phonon dispersion and ab initio molecular dynamics (AIMD) analysis also indicate its good dynamical and thermodynamic stability. Remarkably, the ZnSe/BiOX heterostructures form a type-II band alignment with a direct band gap ranging from 1.78 eV to 2.06 eV, which enables the separation of electrons and holes in two different layers upon visible-light irradiation. The ZnSe/BiOX heterostructures also show high electron mobility, leading to fast migration of photogenerated electrons and extension of their lifetimes. The projected band structure, partial density of states, and partial charge densities show that the electrons of the valence band maximum (VBM) and conduction band minimum (CBM) are located at different sides of the ZnSe/BiOX heterostructures. According to the Bader charge analysis and charge density difference, an internal electric field exists across the interface which will effectively promote the separation of the photoinduced electron–hole pairs. The band-edge positions of the ZnSe/BiOX heterostructures have demonstrated that the band levels of the VBM and CBM stride the oxidation and reduction potential for water splitting. In addition, the band gaps and band-edge positions of the ZnSe/BiOX heterostructures can be tuned by the in-layer biaxial strain. Therefore, our results suggest that ZnSe/BiOX heterostructures are a promising potential application for water splitting under visible light as a novel photocatalyst.

The unique carrier mobility of Janus MoSSe/GaN heterostructures

“…[34] Because heterostructure can not only preserve the property of its individual component, but also introduce advanced functional. [35][36][37] For example, the heterostructure of the different semiconductors could exhibit unusual band gap. [38,39] What's more, intrinsic electric filed may generally exist in the heterostructure, and it would help to separate the carriers.…”

Two-Dimensional Semiconducting ZrNX (X= Cl, Br, I) with a Janus Structure for Solar Energy Utilization

“…But for Janus ones (Figure d–f), there is a great potential drop (1.096, 5.658, and 6.801 eV for Zr 2 N 2 ClBr, Zr 2 N 2 ClI, and Zr 2 N 2 BrI, respectively) between different X atoms layers, which induces a strong electrostatic field to be formed between the layers with transport barriers, implying that electrons are transferred between different X atoms layers . More importantly, the great potential drops have positive significance for low recombination rate and electrostatic potential difference (ΔΦ), which induce intrinsic dipoles to generate a built-in electric field, which is beneficial to the separation of photoinduced electron–hole pairs, improving the performance of (photo)­electric devices. , …”

Controlled synthesis of monodispersed ZnSe microspheres for enhanced photo-catalytic application and its corroboration using density functional theory

“…25 Another such attempt involving ZnSe is the ZnSe/BiOX vertical heterostructure as a promising photocatalyst for water splitting under visible light using first-principles study. 26 Hussain et al have recently used hybrid density functional theory to study the optoelectronic properties of ZnSe 1Àx Te x for photocatalytic applications. 27 They have found that for x = 0.25 and 0.5, the charge carrier separation can be improved and these solid solutions are promising for the photocatalytic reduction of CO 2 and oxidation of water.…”

“…25 Another such attempt involving ZnSe is the ZnSe/BiOX vertical heterostructure as a promising photocatalyst for water splitting under visible light using first-principles study. 26 Hussain et al . have recently used hybrid density functional theory to study the optoelectronic properties of ZnSe 1− x Te x for photocatalytic applications.…”