Synthesis of Zinc Oxide Nanorods from Zinc Borate Precursor and Characterization of Supercapacitor Properties

The synthesis of zinc oxide (ZnO) was accomplished from zinc borate (Zn₃B₂O₆) minerals to be used as electrodes in supercapacitor applications. The concentrations of obtained zinc (Zn) metal after treatment with hydrochloric acid (HCl) were determined by atomic absorption spectroscopy (AAS). Direct synthesis of ZnO on a nickel (Ni) foam surface was conducted by employing the hydrothermal technique using a solution with the highest Zn content. The results showed the successful synthesis of ZnO nanorods on the surface of Ni foam with an average wall size of approximately 358 nm. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurements revealed that the synthesized electrode exhibited battery-type charge storage characteristics, reaching a maximum specific capacitance of approximately 867 mF·cm⁻² at a current density of 2 mA·cm⁻². Additionally, the energy and power densities of the electrode at a current density of 2 mA·cm⁻² were calculated as 19.3 mWh·cm⁻² and 200 mW·cm⁻², respectively. These results exhibited promising performance of the single-component electrode, outperforming the existing counterparts reported in the literature.