Pseudocapacitive charge storage behavior of cation-doped WS2 nanosheets electrode

Abstract

Nanostructured two-dimensional layered semiconductors MX2 (M = Mo, W, and X = S, Se, Te) are potential candidates for electrochemical energy conversion and storage applications. Recently, different research strategies, including phase and heterostructure engineering, surface modification, and chemical doping have been employed with the aim to obtain high energy density MX2 supercapacitor electrodes. Here, we report the electrochemical supercapacitor performance of cation, Co, Ir, and Ru, doped WS2 nanosheets electrode in 1 M Na2SO4 and 2 M H2SO4 aqueous electrolyte. The structure of WS2 nanosheets is stabilized in the 2H hexagonal phase and the interlayer separation expanded after cation doping. The cation-doped WS2 nanosheet electrodes exhibit pseudocapacitive behavior with improved performance in both electrolytes. Among all, the best electrode, Ru doped WS2 nanosheets shows excellent energy storage capacity and attains a specific capacity of 438 Fg−1 in 2 M H2SO4 electrolyte. The analysis reveals that cation doping is one possible research strategy to improve the supercapacitor performance of WS2 nanosheets.