Hydrothermal Synthesis of Co ₃ O ₄ /ZnCo ₂ O ₄ Core-Shell Nanostructures for High-Performance Supercapacitors

Abstract

Supercapacitive properties of Co/ZnCo oxide composite with a core–shell nanostructure (Co 3 O 4 /ZnCo 2 O 4 ) 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 ZnCo 2 O 4 deposits coated onto the surface of Co 3 O 4 nanorods measuring ∼150 nm in diameter. The specific capacitance value of the Co 3 O 4 /ZnCo 2 O 4 core–shell nanostructure synthesized by hydrothermal at 130 °C for a ZnCo 2 O 4 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 Co 3 O 4 scaffolds. The Co 3 O 4 /ZnCo 2 O 4 core–shell structure exhibits excellent electrochemical performances and, as such, is one of the more promising active materials in pseudocapacitor applications.