Hierarchical Co3O4@NiCoLDH nanosheets(NSs)were prepared on carbon cloth through a multistep method,containing Metal-organic frameworks(MOF)-templated thermal annealing and electrodeposition.The triangle-shaped Co3O_(4 NSs)were firstly obtained by thermal treatment of MOF templates in air.Then,ultrathin NiCoLDHNSswere in-situ electrodeposited on the surface of Co3O4NSs,constructing a core-shell structure.Benefiting the unique hierarchical structure,high conductivity of Co3O_(4 NSs)core and large surface area of NiCoLDHNSs shell,the Co3O4@NiCoLDHNSsarray served as supercapacitor electrode exhibits excellent electrochemical properties,such as high specific capacitance of 1708 F g-1(850 C g-1)at a current density of 1 A g-1,good rate capability,and excellent cycling stability.Further,the asymmetric supercapacitor assembled by Co3O4@NiCoLDHNSsand activated carbon,also displays superior electrochemical perfo rmance with high energy density and power density.Remarkably,the strategy of constructing core-shell structure based on MOF templates could be extended to other electrochemical fields. 相似文献
Nitrogen-doped graphene/carbon nanohorns composite(NGLC) was prepared by one-step co-pyrolysis of graphene oxide, carbon nanohorns(CNHs), urea, and lignosulfonate. CNHs as spacers were inserted into graphene nanosheets. The introduction of CNHs and the loosened nano-structure of NGLC make it achieve a high specific capacitance of 363 Fg~(-1) at a discharge current density of 1 A g~(-1), and NGLC exhibits an ultrahigh stability of 93.5% capacitance retention ratio after 5000 cycles. The outstanding comprehensive electrochemical performance of NGLC could meet the need of the future acted as an efficient supercapacitor electrode material. 相似文献
In this work, a novel flower-like cobalt-based metal organic frameworks(MOFs) self-assembled by Co~(2+) and nicotinic acid have been designed and synthesized. After a simple annealing treatment, Co_3O_4 nanoparticles in-situ decorating on nitrogen doped graphite carbon-sheet(Co_3O_4/NC) were obtained. The resultant Co_3O_4/NC hybrid with unique flower-like structure and ration combination of Co_3O_4 nanoparticles and nitrogen doped graphite carbon, endowing the hybrid with enhanced electrical conductivity,short ion diffusion pathways and rich porosity to the materials, which can largely alleviate the problems of Co_3O_4 such as inferior intrinsic electrical conductivity, sluggish ion kinetics and large volume change upon cycling. When evaluated as anode material for sodium-ion batteries(SIBs), the Co_3O_4/NC hybrid exhibits satisfied reversible capacity(213.9 mAh g~(-1) after 100 cycles at 0.1 A g~(-1) ), excellent rate capability(145.4 m Ah g~(-1) at 2 A g~(-1) and 130.1 mAh g~(-1) at 4 A g~(-1) ) and robust long-term cycling stability(120.1 m Ah g~(-1) after 2000 cycles at 0.5 A g~(-1) ), showing great potential for high-performance SIBs. 相似文献
Graphene/MnO2 hybrid nanosheets were prepared by incorporating graphene and MnO2 nanosheets in ethylene glycol. Scanning electron microscopy and transmission electron microscopy analyses confirmed nanosheet morphology of the hybrid materials. Graphene/MnO2 hybrid nanosheets with different ratios were investigated as electrode materials for supercapacitors by cyclic voltammetry (CV) and galvanostatic charge–discharge in 1 M Na2SO4 electrolyte. We found that the graphene/MnO2 hybrid nanosheets with a weight ratio of 1:4 (graphene:MnO2) delivered the highest specific capacitance of 320 F g−1. Graphene/MnO2 hybrid nanosheets also exhibited good capacitance retention on 2000 cycles. 相似文献
Polyaniline/graphene nanocomposites (PANi/GR) were prepared via PANi covalent grafting from the surface of GR. The unique structure of hybrid nanosheets was formed with uniform PANi layer coating GR without phase separation appearing when the weight ratio of aniline-to-graphene was 1:1. The unique PANi/GR hybrid nanosheets as electrode material for supercapacitors have a specific capacitance as high as 922 F/g at 10 mV/s and still retain a specific capacitance of 106 F/g at a high scan rate of 1 V/s due to synergistic effect between PANi and GR. The capacitance retention was ∼90% after 1000 cycles, which is much better than that of pure PANi or other PANi nanocomposites. The enhanced capacitive performance of PANi/GR hybrid nanosheets makes them have potential application in developing high performance energy storage devices. 相似文献
阴极材料的开发对于可充电水相电池的发展具有重要意义.本文通过自牺牲模板法和碳包覆法相结合制备了碳包覆介孔Fe3O4纳米阵列阴极材料(Fe3O4@C MNAs).得益于包覆碳层、介孔结构和纳米阵列结构的优异特性, Fe3O4@C MNAs电极表现出良好的倍率性能和优秀的循环稳定性.在组装的Ni/Fe电池器件中, Fe3O4@C MNAs表现出较高的能量密度及功率密度(在能量密度为213.3 W h kg-1时功率密度为0.658 kW kg-1和在功率密度为20.7 kW kg-1时能量密度为113.9 W h kg-1)和出色的循环稳定性(约5000次循环后保持81.7%). 相似文献
Papillae-like polyaniline (PANI) nanocones arrays growing on graphsene nanosheets (GNs) were synthesized in mass at low cost by in situ polymerization with the assistant of ethanol. Scanning electron microscopy and transmission electron microscopy images show that papillae-like PANI nanocones arrays are located uniformly on flexible two-dimensional GNs. Electrochemical properties are tested by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The electrochemical performances of GNs/PANI hybrid are better than those of bare GNs or PANI. GNs/PANI electrode delivered a maximum specific capacitance of 372 F g?1 at a current density of 0.1 A g?1 in 1.0 M Na2SO4 aqueous solution. And the composite exhibit an excellent cycle life with ~80% specific capacitance retention over 3000 cycles at 1 A g?1. The GNs/PANI nanocomposites will be one of the most promising flexible electrode materials for high-performance ultracapacitors. 相似文献
Ordered mesoporous carbon (CMK-3) was fabricated by a simple nanocasting method using SBA-15 as a hard template. The CMK-3 had a two-dimensional hexagonal mesoporous structure and a specific surface area of approximately 975.9 m2 g?1. The CMK-3 was modified by HNO3 solutions with magnetic stirring and ultrasonic activation, respectively, to explore the influence of various activation methods on pore structure, surface state, morphology, and electrochemical performance. The CMK-3 modified by ultrasonic activation (CMK-3-US) reached the optimal specific capacitance of 233.4 A g?1 at 0.5 A g?1 and retained 94.2% after 500 cycles in 3 M KOH electrolyte. Furthermore, a symmetric supercapacitor was successfully assembled using CMK-3-US electrodes, which delivered an excellent energy density of 21.5 Wh kg?1 at a power density of 225 W kg?1 and exhibited great long-term stability with 97.5% retention after 4000 cycles. Compared to magnetic stirring activation, ultrasonic cavitation could better increase the efficiency of the HNO3 activation for mesoporous carbon particles. The results indicate ultrasonic activation is an efficient way to modify carbon-based electrode materials for supercapacitors. 相似文献
In this work, a functionalized mesoporous carbon (CMK-3-O) was synthesized after oxidation with nitric acid and was used to adsorb dibenzothiophene (DBT) from model oil for the first time. Then, its performance was compared with that of CMK-3. The functionalized mesoporous carbon, CMK-3-O, showed better a capacitance performance for DBT adsorption than that of CMK-3. The maximum adsorption capacity was obtained for functionalized mesoporous carbon at optimum conditions with 6 M HNO3 aqueous solution and 30 min contact time. The physical and structural properties of CMK-3-O and CMK-3 were investigated with X-ray diffraction method (XRD), N2 adsorption–desorption isotherm, FT-IR, and elemental analysis (CHNO). Results of the elemental analysis showed that the oxygen and nitrogen content has increased and the carbon content has decreased through oxidation treatment. The effects of various factors on the adsorption process (such as temperature, amount of adsorbent, contact time, and concentration) of DBT were studied. CMK-3-O showed a maximum adsorption capacity of 86.96 mg DBT g?1 of CMK-3-O at optimized conditions (temperature, 25°C; adsorbent dosage, 20 g L?1; contact time, 60 min), which was a higher adsorption capacity of that observed for CMK-3 (57.47 mg DBT g?1 of CMK-3). Kinetic studies have revealed that the adsorption of DBT can be described by a pseudo-second-order rate equation. Equilibrium data showed that adsorption process was best represented by the Langmuir model. The results also illustrated the fact that the regenerated adsorbent afforded 64.3% of the initial adsorption capacity after the two regeneration cycles. 相似文献
Triangular Ni(HCO3)2 nanosheets were synthesized via a template-free solvothermal method. The phase transition and formation mechanism were explored systematically. Further investigation indicated that the reaction time and pH have significant effects on the morphology and size distribution of the triangular Ni(HCO3)2 nanosheets. More interestingly, the resulting product had an ultra-thin structure and high specific surface area, which can effectively accelerate the charge transport during charge–discharge processes. As a result, the triangular Ni(HCO3)2 nanosheets not only exhibited high specific capacitance (1,797 F·g-1 at 5 A·g-1 and 1,060 F·g-1 at 50 A·g-1), but also showed excellent cycling stability with a high current density (~80% capacitance retention after 5,000 cycles at the current density of 20 A·g-1).
Al foil was coated with niobium oxide by cathodic electroplating and anodized in a neutral boric acid solution to achieve high capacitance in a thin film capacitor. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) revealed the niobium oxide layer on Al to be a hydroxide-rich amorphous phase. The film was crystalline and had stoichiometric stability after annealing at temperatures up to 600 °C followed by anodizing at 500 V, and the specific capacitance of the Nb2O5-Al2O3 composite oxide was approximately 27% higher than that of Al2O3 without a Nb2O5 layer. The capacitance was quite stable to the resonance frequency. Overall, the Nb2O5-Al2O3 composite oxide film is a suitable material for thin film capacitors. 相似文献