Fabrication of Ni(OH)2 coated ZnO array for high-rate pseudocapacitive energy storage

Improving the specific capacity of nickel hydroxide nanocrystalsviayttrium doping for application in hybrid supercapacitors

Herein, Y-doped Ni(OH)₂composites were successfully fabricatedviaa simple hydrothermal process.

NiCo2S4@Ni3S2 hybrid nanoarray on Ni foam for high-performance supercapacitors

Integrated hybrid nanoarrays with hierarchical porous structures have attracted much attention as energy materials for their excellent synergistic effects.

Three-Dimensional Hierarchical Structure ZnO@C@NiO on Carbon Cloth for Asymmetric Supercapacitor with Enhanced Cycle Stability

In this work, we synthesized the hierarchical ZnO@C@NiO core-shell nanorods arrays (CSNAs) grown on a carbon cloth (CC) conductive substrate by a three-step method involving hydrothermal and chemical bath methods. The morphology and chemical structure of the hybrid nanoarrays were characterized in detail. The combination and formation mechanism was proposed. The conducting carbon layer between ZnO and NiO layers can efficiently enhance the electric conductivity of the integrated electrodes, and also protect the corrosion of ZnO in an alkaline solution. Compared with ZnO@NiO nanorods arrays (NAs), the NiO in CC/ZnO@C@NiO electrodes, which possess a unique multilevel core-shell nanostructure exhibits a higher specific capacity (677 C/g at 1.43 A/g) and an enhanced cycling stability (capacity remain 71% after 5000 cycles), on account of the protection of carbon layer derived from glucose. Additionally, a flexible all-solid-state supercapacitor is readily constructed by coating the PVA/KOH gel electrolyte between the ZnO@C@NiO CSNAs and commercial graphene. The energy density of this all-solid-state device decreases from 35.7 to 16.0 Wh/kg as the power density increases from 380.9 to 2704.2 W/kg with an excellent cycling stability (87.5% of the initial capacitance after 10000 cycles). Thereby, the CC/ ZnO@C@NiO CSNAs of three-dimensional hierarchical structure is promising electrode materials for flexible all-solid-state supercapacitors.

Facile Synthesis ZnS/ZnO/Ni(OH)2 Composites Grown on Ni Foam: A Bifunctional Materials for Photocatalysts and Supercapacitors

A facile one-step hydrothermal reaction was employed to synthesis an integrated bifunctional composite composed by a network structure of ZnS/ZnO/Ni(OH)₂ nanosheets with ZnS/ZnO nanospheres in situ growing on Ni foam. The synergistic effect of these three substances make the composite having both improved electrochemical performances and photocatalytic activity. The ZnS/ZnO/Ni(OH)₂-4mmol shows a high specific capacitance of 1173.8 F g⁻¹ at 1 A g⁻¹, as well as good rate capability and relatively stable cyclability. Using as photocatalyst, the methyl orange dye in solution can be completely decomposed under ultraviolet-visible radiation in about 80 min. And the composite is easy to be repeatedly used because bulk Ni foam was used as a carrier. Such a bifunctional composite material provides a new insight for energy storage and utilization as well as the water pollution treatment.

Surface-Charge-Mediated Formation of H-TiO2 @Ni(OH)2 Heterostructures for High-Performance Supercapacitors

An electrochemically favorable Ni(OH)₂ with porously hierarchical structure and ultrathin nanosheets in a core-shell structure H-TiO₂ @Ni(OH)₂ is achieved through modulating the surface chemical activity of TiO₂ by hydrogenation, which creates a defect-rich surface of TiO₂ , thereby facilitating the subsequent nucleation and growth of Ni(OH)₂ . These configuration-tailored H-TiO₂ @Ni(OH)₂ core-shell nanowires exhibit a superior electrochemical performance and good flexibility.

Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method

Mn-doped TiO₂ micro/nanostructure porous film was prepared by anodizing a Ti-Mn alloy. The film annealed at 300 °C yields the highest areal capacitance of 1451.3 mF/cm² at a current density of 3 mA/cm² when used as a high-performance supercapacitor electrode. Areal capacitance retention is 63.7% when the current density increases from 3 to 20 mA/cm², and the capacitance retention is 88.1% after 5,000 cycles. The superior areal capacitance of the porous film is derived from the brush-like metal substrate, which could greatly increase the contact area, improve the charge transport ability at the oxide layer/metal substrate interface, and thereby significantly enhance the electrochemical activities toward high performance energy storage. Additionally, the effects of manganese content and specific surface area of the porous film on the supercapacitive performance were also investigated in this work.

Hierarchical core/shell structures of ZnO nanorod@CoMoO4 nanoplates used as a high-performance electrode for supercapacitors

ZnO@CoMoO₄ core/shell structures as an electrode for supercapacitors exhibited a high specific capacitance of 1.52 F cm⁻² (1169 F g⁻¹) at 2 mA cm⁻² and a good cycling stability of 109% of the initial specific capacitance after 5000 cycles.

Flower-like ZnO@MnCo2O4 nanosheet structures on nickel foam as novel electrode material for high-performance supercapacitors

The flower-like ZnO@MnCo₂O₄ nanosheet electrode exhibited high specific capacitance than dandelion-like MnCo₂O₄.

Au-embedded ZnO/NiO hybrid with excellent electrochemical performance as advanced electrode materials for supercapacitor

Here we design a nanostructure by embedding Au nanoparticles into ZnO/NiO core-shell composites as supercapacitors electrodes materials. This optimized hybrid electrodes exhibited an excellent electrochemical performance including a long-term cycling stability and a maximum specific areal capacitance of 4.1 F/cm(2) at a current density of 5 mA/cm(2), which is much higher than that of ZnO/NiO hierarchical materials (0.5 F/cm(2)). Such an enhanced property is attributed to the increased electro-electrolyte interfaces, short electron diffusion pathways and good electrical conductivity. Apart from this, electrons can be temporarily trapped and accumulated at the Fermi level (EF') because of the localized schottky barrier at Au/NiO interface in charge process until fill the gap between ZnO and NiO, so that additional electrons can be released during discharge. These results demonstrate that suitable interface engineering may open up new opportunities in the development of high-performance supercapacitors.

Three dimensional carbon nanotube/nickel hydroxide gels for advanced supercapacitors

CNT gel composite presenting different structures have been developed with excellent electrochemical performance for supercapacitor applications.

NiMoO4@Ni(OH)2 core/shell nanorods supported on Ni foam for high-performance supercapacitors

The NiMoO₄ nanorods were used as the backbone to support and provide reliable electrical connection to the Ni(OH)₂ nanosheets for supercapacitor applications.

High-performance supercapacitor electrode based on the unique ZnO@Co₃O4₄ core/shell heterostructures on nickel foam

Currently, tremendous attention has been paid to the rational design and synthesis of unique core/shell heterostructures for high-performance supercapacitors. In this work, the unique ZnO@Co3O4 core/shell heterostructures on nickel foam are successfully synthesized through a facile and cost-effective hydrothermal method combined with a short post annealing treatment. Mesoporous Co3O4 nanowires are multidirectional growing on the rhombus-like ZnO nanorods. In addition, the growth mechanism for such unique core/shell heterostructures is also proposed. Supercapacitor electrodes based on the ZnO@Co3O4 and Co3O4 heterostructures on nickel foam are thoroughly characterized. The ZnO@Co3O4 electrode exhibits high capacitance of 1.72 F cm(-2) (857.7 F g(-1)) at a current density of 1 A g(-1), which is higher than that of the Co3O4 electrode. Impressively, the capacitance of the ZnO@Co3O4 electrode increases gradually from 1.29 to 1.66 F cm(-2) (830.8 F g(-1)) after 6000 cycles at a high current density of 6 A g(-1), indicating good long-term cycling stability. These results indicate the unique ZnO@Co3O4 electrode would be a promising electrode for high-performance supercapacitor applications.

Recent development of metal hydroxides as electrode material of electrochemical capacitors

Recent research on electrochemical capacitors using transition metal hydroxides as electrode materials is reviewed.