Nanoscale synergy: Optimizing energy storage with SnO ₂ quantum dots on ZnO hexagonal prisms for advanced supercapacitors

Abstract Electrode materials comprising SnO ₂ quantum dots embedded within ZnO hexagonal prisms were successfully synthesized for building cost-effective energy-storage devices. Extensive structural and functional characterizations were performed to assess the electrochemical performance of the electrodes. SEM–EDS results confirm a uniform distribution of SnO ₂ quantum dots across ZnO. The integration of SnO ₂ quantum dots with ZnO hexagonal prisms markedly improved the electrochemical behavior. The analysis of electrode functionality conducted in a 3 M KOH electrolyte revealed specific capacitances of 949.26 and 700.68 F g⁻ ¹ for SnO ₂ @ZnO and ZnO electrodes, respectively, under a current density of 2 A g⁻ ¹ . After undergoing 5,000 cycles at a current density of 15 A g⁻ ¹ , the SnO ₂ @ZnO and ZnO electrodes displayed impressive cycling stability, maintaining specific capacitance retention rates of 89.9 and 92.2%, respectively. Additionally, a symmetric supercapacitor (SSC) device constructed using the SnO ₂ @ZnO electrode showcased exceptional performance, exhibiting a specific capacitance of 83 F g⁻ ¹ at 1.2 A g⁻ ¹ . Impressive power and energy densities were achieved by the device, with values reaching 2,808 and 70.2 W kg⁻ ¹ , respectively. Notably, the SnO ₂ @ZnO SSC device maintained a capacity preservation of 75% throughout 5,000 galvanostatic charge–discharge sequences. The outcomes highlight the potential of SnO ₂ @ZnO hexagonal prisms as candidates for energy-storage applications, offering scalability and cost-effectiveness. The proposed approach enhances the electrochemical performance while ensuring affordability, facilitating the creation of effective and financially feasible energy storage solutions.