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.