Layer-structured copper antimony chalcogenides (CuSbSe<inf>x</inf>S<inf>2-x</inf>): Stable electrode materials for supercapacitors

The ever-growing need for energy generation and storage applications demands development of materials with high performance and long-term stability. A sizable number of chalcogenide-based materials have been investigated for supercapacitor applications. Layer-structured chalcogenides are advantageous in terms of providing large surface area with good ionic conductivity and ability to host a variety of atoms or ions between the layers. CuSbS2 is a ternary layered chalcogenide material that is composed of earth abundant and less-toxic elements. For the first time, we have developed a simple colloidal method for the synthesis of CuSbSexS2-x mesocrystals over the whole composition range (0 ≥ x ≥ 2) by substitution of S with Se. Our approach yields mesocrystals with belt-like morphology for all the compositions. X-ray diffraction results show that substitution of sulfur with selenium in CuSbS2 enables tuning the width of the interlayer gap between the layers. To investigate the suitability of CuSbSexS2-x mesocrystals for supercapacitor applications, we have carried out electrochemical measurements by cyclic voltammetry and galvanostatic charge-discharge measurements in 3 M KOH, NaOH and LiOH electrolytes. Our investigations reveal that the mesocrystals exhibit promising specific capacitance values with excellent cyclic stability. The unique properties of CuSbSexS2-x mesocrystals make them attractive both for solar energy conversion and energy storage applications.