Hierarchical architecture of the metallic VTe2/Ti3C2Tx MXene heterostructure for supercapacitor applications

Abstract

Layered two-dimensional (2D) materials demonstrate exceptional performance as supercapacitor electrodes due to their unique intrinsic properties. A hybrid 2D/2D heterostructured electrode material can synergize the individual energy storage features of each of the layered 2D materials. Ti₃C₂ MXene is an emergent 2D material with enriched energy storage capabilities but suffers from certain vulnerabilities during the charge storage process. Vanadium ditelluride (VTe₂) is an interesting yet unexplored layered material within the 2D transition metal dichalcogenide (TMD) family. Owing to the unique structural features, VTe₂ showcases certain advantages in energy storage. The formation of the VTe₂/Ti₃C₂ MXene heterostructure for energy storage applications has not been reported until now. Herein, we report a facile and simple hydrothermal synthesis approach to prepare bare VTe₂ and the VTe₂/MXene heterostructure for supercapacitor applications. The energy storage mechanism in the heterostructure is systematically analyzed. The synergistically induced interplaying effects enhance the specific capacitance of the heterostructure to 250 F g⁻¹ along with excellent durability during long cycle operation. Consequently, an asymmetric system is constructed with VTe₂/MXene as the positive electrode and MoS₂/MXene as the negative electrode. The 2D/2D heterostructure-based asymmetric supercapacitor delivers excellent performance with an energy density of 46.3 W h kg⁻¹ and a highest power density of 6400 W kg⁻¹. Furthermore, the density functional theory calculations predict that the enhancement of electronic Te 5P states near the Fermi level due to MXene leads to improved performance of the VTe₂/Ti₃C₂ hybrid for supercapacitor applications.