Hydrothermal Synthesis of Co₃O₄/ZnCo₂O₄Core-Shell Nanostructures for High-Performance Supercapacitors

Supercapacitive properties of Co/ZnCo oxide composite with a core-shell nanostructure (Co3O4/ZnCo2O4) prepared directly onto a nickel foam substrate by a two-step hydrothermal method were investigated. The synthesized core-shell structure consisted of some ~40-100 nm in thick flaky ZnCo2O4 deposits coated onto the surface of Co3O4 nanorods measuring ~150 nm in diameter. The specific capacitance value of the Co3O4/ZnCo2O4 core-shell nanostructure synthesized by hydrothermal at 130 °C for a ZnCo2O4 deposition time of 2 h can attain 1804 F g-1 at a scan rate of 5 mV s-1. Furthermore, the core-shell structured electrode still exhibited a relatively good capacitance retention of more than 93% after 3000 CV cycles due to the superior structural support of Co3O4 scaffolds. The Co3O4/ZnCo2O4 core-shell structure exhibits excellent electrochemical performances and, as such, is one of the more promising active materials in pseudocapacitor applications.