Abstract
Recently, GaTe and C2N monolayers have been successfully synthesized and show fascinating electronic and optical properties. Such hybrid of GaTe with C2N may induce new novel physical properties. In this work, we perform ab initio simulations on the structural, electronic, and optical properties of the GaTe/C2N van der Waals (vdW) heterostructure. Our calculations show that the GaTe/C2N vdW heterostructure is an indirect-gap semiconductor with type-II band alignment, facilitating an effective separation of photogenerated carriers. Intriguingly, it also presents enhanced visible-UV light absorption compared to its components and can be tailored to be a good photocatalyst for water splitting at certain pH by applying vertical strains. Further, we explore specifically the adsorption and decomposition of water molecules on the surface of C2N layer in the heterostructure and the subsequent formation of hydrogen, which reveals the mechanism of photocatalytic hydrogen production on the 2D GaTe/C2N heterostructure. Moreover, it is found that in-plane biaxial strains can induce indirect-direct-indirect, semiconductor-metal, and type II to type I or type III transitions. These interesting results make the GaTe/C2N vdW heterostructure a promising candidate for applications in next generation of multifunctional optoelectronic devices.
Highlights
Ever since the discovery of graphene [1, 2], interest in two-dimensional (2D) layered materials has been growing steadily
Many studies demonstrated that its bandgap, band edge positions, and optical properties can be engineered by varying their stacking order, layer number, external electric field or strain and alloying/substituting with other elements [13,14,15,16]
The conduction band minimum (CBM) and valence band maximum (VBM) calculated using PBE and Hybrid Heyd-Scuseria-Ernzerhof (HSE06) are all at points, indicating the band dispersions given by the two functionals are relatively consistent though there is some difference in accuracy
Summary
Ever since the discovery of graphene [1, 2], interest in two-dimensional (2D) layered materials has been growing steadily. Many graphene-like 2D materials such as transition-metal dichalcogenides [3], monolayer honeycomb structures of group V elements and III-V binary compounds [4,5,6,7,8], and post transition metal chalcogenides (PTMCs)[9] have gained a lot of interest due to their exceptional physical properties and promising applications. Among these diverse 2D materials, GaTe monolayer, as a member of PTMCs [9], has successfully been fabricated by molecular beam epitaxy [10]. A significant challenge still remains for the use of C2N in photocatalysis and photovoltaic cells: The photogenerated electron-hole pairs stay in the same regions spatially, which can lead to a high rate of recombination of photogenerated carriers, reducing the solar energy conversion
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