Electrophoretic deposition of RGO-NiO core-shell nanostructures driven by heterocoagulation method with high electrochemical performance

Electrophoretic Fabrication of ZnO/CuO and ZnO/CuO/rGO Heterostructures-based Thin Films as Environmental Benign Flexible Electrode for Supercapacitor

Sustainable fabrication of flexible hybrid supercapacitor electrodes is extensively investigated during the current era to solve global energy problems. Herein, we used a cost-effective and efficient electrophoretic deposition (EPD) approach to fabricate a hybrid supercapacitor electrode. ZnO/CuO and ZnO/CuO/rGO heterostructure were prepared by sol-gel synthesis route and were electrophoretically deposited on indium tin oxide (ITO) substrate as a thin uniform layer using 1 V for 20 min at 50 mV/s. ZnO/CuO and ZnO/CuO/rGO heterostructure coated ITOs were then employed as the working electrode in a three-electrode setup for supercapacitor measurements. The fabricated electrodes have been investigated by Galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) to study their charge storage properties. ZnO/CuO revealed a specific capacitance of 1945 F g^-1 at 2 mV/s and 999 F g^-1 at 5 A g^-1. However, an increased specific capacitance of 2305 F g^-1 was measured for ZnO/CuO/rGO heterostructure at 2 mV/s and 1235 F g^-1 at 5 A g^-1. The lower internal resistance was observed for ZnO/CuO/rGO heterostructure, indicating good conductivity of the electrode material. Thus, the overall results of the current study suggest that EPD-assisted ZnO/CuO/rGO heterostructure hybrid electrode possess a substantial potential for energy storage as a supercapacitor.

Effect of Hydrothermal Method Temperature on the Spherical Flowerlike Nanostructures NiCo(OH)4-NiO

NiCo(OH)4-NiO composite electrode materials were prepared using hydrothermal deposition and electrophoretic deposition. NiCo(OH)4 is spherical and flowerlike, composed of nanosheets, and NiO is deposited on the surface of NiCo(OH)4 in the form of nanorods. NiCo(OH)4 has a large specific surface area and can provide more active sites. Synergistic action with NiO deposits on the surface can provide a higher specific capacitance. In order to study the influence of hydrothermal reaction temperature on the properties of NiCo(OH)4, the prepared materials of NiCo(OH)4-NiO, the hydrothermal reaction temperatures of 70 °C, 90 °C, 100 °C, and 110 °C were used for comparison. The results showed that the NiCo(OH)4-NiO-90 specific capacitance of the prepared electrode material at its maximum when the hydrothermal reaction temperature is 90 °C. The specific capacitance of the NiCo(OH)4-NiO-90 reaches 2129 F g−1 at the current density of 1 A g−1 and remains 84% after 1000 charge–discharge cycles.

Porous spherical NiO@NiMoO4@PPy nanoarchitectures as advanced electrochemical pseudocapacitor materials

In this work, a rational design and construction of porous spherical NiO@NiMoO₄ wrapped with PPy was reported for the application of high-performance supercapacitor (SC). The results show that the NiMoO₄ modification changes the morphology of NiO, and the hollow internal morphology combined with porous outer shell of NiO@NiMoO₄ and NiO@NiMoO₄@PPy hybrids shows an increased specific surface area (SSA), and then promotes the transfer of ions and electrons. The shell of NiMoO₄ and PPy with high electronic conductivity decreases the charge-transfer reaction resistance of NiO, and then improves the electrochemical kinetics of NiO. At 20Ag^-1, the initial capacitances of NiO, NiMoO₄, NiO@NiMoO₄ and NiO@NiMoO₄@PPy are 456.0, 803.2, 764.4 and 941.6Fg^-1, respectively. After 10,000 cycles, the corresponding capacitances are 346.8, 510.8, 641.2 and 904.8Fg^-1, respectively. Especially, the initial capacitance of NiO@NiMoO₄@PPy is 850.2Fg^-1, and remains 655.2Fg^-1 with a high retention of 77.1% at 30Ag^-1 even after 30,000 cycles. The calculation result based on density function theory shows that the much stronger Mo-O bonds are crucial for stabilizing the NiO@NiMoO₄ composite, resulting in a good cycling stability of these materials.