Microwave-engineered sulphur-doped zirconia quantum dots for supercapacitor applications

The growing global demand for clean energy underscores the importance of developing sustainable energy storage technologies. In response to this urgent demand, quantum dots (QDs) of sulphur-doped zirconia were synthesized through microwave-assisted solution combustion route as a step towards clean energy storage solution. The prepared QDs were characterized to confirm the structural, microstructural, compositional and textural properties. Powder X-ray diffraction (PXRD) studies revealed cubic structure and the low crystallinity of QDs. The nanocrystalline nature of the synthesized QDs was investigated from TEM analysis and the mean crystallite is estimated be 4 nm. The elemental composition was confirmed from Energy dispersive and CHNS analyses. The textural properties of the QDs were investigated using nitrogen adsorption isotherm, which revealed a high surface area. The electrochemical characteristics of the fabricated electrode from the QDs confirmed the pseudocapacitance behaviour of the prepared QDs reaching a specific capacitance of 154.8 F g−1 at a current density of 1.5 A g−1. The electrode demonstrates excellent capacitance retention throughout 2000 charge-discharge cycles.