Synthesis of tungsten disulfide quantum dots for high-performance supercapacitor electrodes

Two-dimensional layered transition metal dichalcogenides, such as tungsten disulfide (WS2) and molybdenum disulfide (MoS2), have been regarded as promising active materials for capacitive energy storage owing to their large specific surface area and multi-valence state of metals to pseudo-capacitive reactions. Here, WS2 quantum dots (QDs) with uniform size were synthesized via a simple method and their pseudo-capacitance properties were investigated. The electrochemical performance was further improved by using surface treatment with 1,2-ethanedithiol. A specific capacitance (C-F) of 457 F/g was thus achieved. Simultaneously, the outstanding cycling stability (8000 cycles) and coulombic efficiency of 81% were obtained. The results suggest that WS2 QDs are an excellent candidate for high performance energy storage devices. (C) 2019 Published by Elsevier B.V.