Enhanced thermoelectric properties of 2D W_xMo_(1-x)S_2 alloys based vertical heterostructures for energy storage applications

摘要

Individual 2-dimensional materials exhibit remarkable properties, but neither of them can show all the required attributes. Stacking different 2-dimensional materials in hetero-layered architecture unlock the combined advantages of the individual building blocks. In recent experiments 2-dimensional vertical heterostructures of graphene/hBN/W_xMo_(1-x)S_2 have been successfully grown. Herein, using the first-principles method, we have analyzed the stability, electronic band structures, and electronic transport coefficients of such vertical heterostruc-ture at 300 K. The calculated bandgap of the pristine monolayer of graphene, hBN, MoS_2, and WS_2 is 0 eV, 3.1 eV, 1.6 eV, and 1.8 eV, respectively. Furthermore, we have observed the atomic level phenomena of bandgap opening in graphene upon changing the interlayer distance. Electrical conductivity (σ/τ) and thermoelectric power factor (PF/τ) are calculated as a function of Fermi energy (E_F). At the studied E_F range, for the graphene/hBN/W_xMo_(1-x)S_2 2D vertical heterostructure, the achieved electrical conductivity and thermoelectric power factor are 0.7×10~(20)Ω~(-1)m~(-1)s~(-1) and 0.75×10~(11) Wm~(-1)K~(-2)s~(-1), respectively. Our findings provide solid outlines for TMDs alloyed based thin-layer 2D heterostructures that could play a crucial role in revolutionizing energy storage devices and expanding all limits of current technologies in super-capacitors and next-generation reliable batteries due to its slit-shaped diffusion channel and high surface to mass ratio, which could enable the fast movements of ions approaching the excellent electrochemical properties.