Abstract:
The objectives of this thesis are to investigate the preparation, characterization and supercapacitive properties of nickel cobaltite/reduced graphene oxide (NiCo₂O₄/rGO) nanocomposites. In the preparation, NiCo₂O₄ powder sample was firstly synthesized using a simple co-precipitation method, then NiCo₂O₄/rGO nanocomsite samples were prepared via a direct mixing of NiCo₂O₄ suspended in vitamin C solution with the different amount of graphene oxide (GO) nanosheets loading (0.1, 0.5, 1.0 and 2.0 wt%) and followed by thermal reduction of the composites under rapid heat at 300ºC for 2 hours to converse GO to rGO. After that, all the as-prepared NiCo₂O₄/rGO samples were confirmed and characterized by X-ray powder diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) techniques. The results demonstrated that the crystalline phases and functional groups of all NiCo₂O₄/rGO nanocomposite samples are corresponding to pristine NiCo₂O₄ and rGO samples. SEM results showed that the NiCo₂O₄ particles had microflowerlike structure, meanwhile NiCo₂O₄/rGO composite samples indicated that NiCo₂O₄/rGO particles were well-combined and impregnated with rGO nanosheets. Moreover, the supercapacitive properties of pristine NiCo₂O₄ and NiCo₂O₄/rGO nanocomposites were studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) techniques. The results revealed that all the NiCo₂O₄/rGO composites exhibited the supercapative behavior, and which much higher supercapacitor performances than those of the pristive NiCo₂O₄ (without rGO loading). The supercapacitor performances for the NiCo₂O₄/rGO samples were increased only with the increasing of rGO loading. This result implied that the NiCo₂O₄ incorporated with rGO nanosheets may be used as a supercapacitor for smart material in the future.