Pseudocapacitive charge storage behavior of cation-doped WS₂ nanosheets electrode

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.