Hydrothermal Synthesis of Co3O4/ZnCo2O4 Core-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 at a scan rate of 5 mV/s. 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.

Evaluate the Humidity Sensing Properties of a CNTs/Co3O4 Nanorods Composite

For the development of humidity sensors, MWCNTs/Co3O4 nanocomposite has been prepared by precipitation method. in order to evaluate the prepared materials quality both of functionalized MWCNTs and decorated CNTs characterized by X- ray powder diffraction (XRD) ,High resolution transmission electron microscope (HRTEM) Thermal analysis (DTA and TGA) FTIR and finally Raman spectroscopy. Meanwhile the humidity sensing behavior has been also investigated. The proposed composite has been tested in the wide range in relative humidity and tesing frequency. The obtained results confirmed that the optimum testing frequency is 100 Hz. The MWCNTs/Co3O4 nanocomposite exhibited a good sensitivity toward humidity from11% up to 97% RH with reasonable response and recovery time. Also the sensor revealed a low hysteresis and good repeatability with increasing and decreasing of humidity levels.