Bridging the gap: an in-depth comparison of CVT-grown layered transition metal dichalcogenides for supercapacitor applications

Abstract

Layered transition metal dichalcogenides (TMDCs) have garnered immense interest in supercapacitor energy storage applications. Despite the growing reports on TMDCs in the context of electrochemical supercapacitor studies, the prevailing use of carbon-based additives often obscures their correct analysis and overshadows their intrinsic behavior. In this work, we meticulously analyzed supercapacitor characteristics of distinct TMDC materials without using carbon or any other conductive, revealing their pure intrinsic behavior, specifically focusing on highly crystalline 2H phase tantalum (Ta), tungsten (W) and zirconium (Zr)-based TMDCs, grown using the chemical vapor transport (CVT) technique. The grown materials were characterized using cutting-edge techniques like X-ray diffraction (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM), ensuring a comprehensive perspective of the synthesized TMDCs. To delve into the electrochemical properties of the prepared electrodes, extensive analysis using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) was performed. The obtained results were further supported with density functional theory (DFT) calculations to get insights regarding the charge transfer mechanism and electronic density distribution proximate to the Fermi levels. The synergy between the experimental results and theoretical calculations significantly improved the validity of our findings, thus probing the comprehension and optimization avenues of TMDCs for superior supercapacitor performance.