Transition metal hydroxides and graphene composite holds great promise to be the next generation of high performance electrode material for energy storage applications. Here we fabricate the cypress leaf-like Cu(OH)
2
nanostructure/graphene nanosheets composite through one-step in situ synthesis process, employed as a new type of electrode material for high efficiency electrochemical energy storage in supercapacitors. A solution-based two-electrode system is applied to synthesize Cu(OH)
2
/graphene hybrid nanostructure, where anodic graphene nanosheets firmly anchor cathodic Cu(OH)
2
nanostructure due to the electrostatic interaction. The in situ self-assembly of Cu(OH)
2
/graphene ensures good structural robustness and the cypress leaf-like Cu(OH)
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nanostructure prompt to form the open and porous morphology. The hybrid structure would facilitate charge transport and effectively mitigate the volume changes during long-term charging/discharging cycles. As a consequence, the Cu(OH)
2
/graphene composite exhibits the highest capacitance of 317 mF/cm
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at the current density of 1 mA/cm
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and superior cyclic stability with no capacitance decay over 20,000 cycles and remarkable rate capability at increased current densities.
Bimetal oxide with its intricate nanostructure holds great potential for high‐performance electrode materials in lithium‐ion batteries (LIBs). Herein, a facile strategy for the fabrication of hierarchical hollow Co3O4/ZnCo2O4 microspheres is developed, involving a simple solvothermal synthesis and subsequent thermal annealing in air. An aggregation‐dissolution‐in situ recrystallization structure evolution and growth mechanism is proposed. Benefiting from the unique hierarchical hollow structure with rational porosity, synergistic effect of bimetal components, and better electrical conductivity, the as‐synthesized Co3O4/ZnCo2O4 hierarchical hollow microstructure shows outstanding lithium storage properties. As a result, a superior rate capability (842 mA h g−1 at a current density of 4 A g−1) and an excellent cycle life (754 mA h g−1 after 800 cycles at a current density of 2 A g−1) are obtained. The presented strategy could be applicable to the synthesis of mixed metal oxide hierarchical hollow structures with rational porosity for high‐performance LIBs.
The demand for a new generation of high-safety, long-lifespan, and high-capacity power sources increases rapidly with the growth of energy consumption in the world. Here we report a facile method for preparing architecture materials made of NiO/Ni x Co 3Àx O 4 porous nanosheets coupled with NiO/Ni x Co 3Àx O 4 porous nanowires grown in situ on nickel foams using a hydrothermal method without any binder followed by a heat treatment process. The nanosheet-shaped NiO/Ni x Co 3Àx O 4 species in the nanosheet matrix function well as a scaffold and support for the dispersion of the Ni x Co 3Àx O 4 nanowires, resulting in a relatively loose and open structure within the electrode matrix. Among all composite electrodes prepared, the one annealed in air at 300 C displays the best electrochemical behavior, achieving a specific capacitance of 270 mF cm À2 at 5 mA cm À2 while maintaining excellent stability (retaining z 89% of the max capacitance after 20 000 cycles), demonstrating its potential for practical application in power storage devices. Fig. 2 (a) XPS survey spectrum, (b) the high-resolution XPS spectrum of Ni 2p, (c) the high-resolution XPS spectrum of Co 2p, and (d) XPS spectrum of O 1s for the NiO/Ni x Co 3Àx O 4 nanostructures.This journal is
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