The design and fabrication of Co_3O_4/Co_3V_2O_8/Ni nanocomposites as high-performance anodes for Li-ion batteries

The Co_3O_4/Co_3V_2O_8/Ni nanocomposites were rationally designed and prepared by a two-step hydrothermal synthesis and subsequent annealing treatment. The one-dimensional(1D) Co_3O_4 nanowire arrays directly grew on Ni foam, whereas the 1D Co_3V_2O_8 nanowires adhered to parts of Co_3O_4 nanowires.Most of the hybrid nanowires were inlayed with each other, forming a 3D hybrid nanowires network.As a result, the discharge capacity of Co_3O_4/Co_3V_2O_8/Ni nanocomposites could reach 1201.8 mAh/g after100 cycles at 100 mA/g. After 600 cycles at 1 A/g, the discharge capacity was maintained at 828.1 mAh/g.Moreover, even though the charge/discharge rates were increased to 10 A/g, it rendered reversible capacity of 491.2 mAh/g. The superior electrochemical properties of nanocomposites were probably ascribed to their unique 3D architecture and the synergistic effects of two active materials. Therefore, such Co_3O_4/Co_3V_2O_8/Ni nanocomposites could potentially be used as anode materials for high-performance Li-ion batteries.     

氢氧化镍纳米线/三维石墨烯复合材料的制备及其电化学性能

采用水热法制备了氢氧化镍纳米线/三维石墨烯复合材料及作为比较的三维石墨烯、氢氧化镍纳米线、还原氧化石墨烯和氢氧化镍纳米线/还原氧化石墨烯, 通过X射线衍射、扫描电镜、热失重分析和氮气吸脱附表征了材料的形貌、结构和组成, 并采用循环伏安法和恒电流充放电测试了复合材料的电化学性能. 结果表明: 氢氧化镍纳米线/三维石墨烯复合材料中直径为20-30 nm的氢氧化镍纳米线和三维结构的石墨烯紧密结合, 相互交联形成网状结构, 其比表面积达到136 m²·g^-1, 孔径分布20-50 nm, 氢氧化镍纳米线的含量达到88% (w,质量分数). 在6 mol·L^-1的KOH电解液中, 复合材料的比电容在1 A·g^-1电流密度下达到1664 F·g^-1, 在1 A·g^-1电流密度下循环3000 次后的比电容保持率为93%. 将复合材料的比电容和循环性能与氢氧化镍纳米线、氢氧化镍纳米线/还原氧化石墨烯、三维石墨烯和还原氧化石墨烯的性能进行比较, 发现三维石墨烯较还原氧化石墨烯具有更高的比表面积和三维多孔结构, 可以更大地提高活性物质的利用率, 进而提高复合材料的比电容和稳定性.     

泡沫镍载 NiCO2O4电极的制备及其催化 H2O2电氧化的性能

本文以水热法结合热处理法原位制备了泡沫镍载 NiCo₂O₄纳米线电极,使用XRD、SEM和TEM对合成的 NiCo₂O₄纳米线进行了表征,NiCo₂O₄纳米线直径约80 nm,长度约 3 ~ 5 μm. 使用循环伏安和计时电流法测试了泡沫镍载NiCo₂O₄纳米线催化H₂O₂的电氧化性能,结果表明泡沫镍载NiCo₂O₄纳米线对H₂O₂电氧化有着优良的催化活性、稳定性和传质性能,在0.3 V电位下0.4 mol·L ^-1 H₂O₂和2 mol·L ^-1 NaOH溶液中氧化电流可达380 mA·cm ^-2.     

Integrated Ni_2P nanosheet arrays on three-dimensional Ni foam for highly efficient water reduction and oxidation

The large-scale synthesis of efficient nonprecious bifunctional electrocatalysts for overall water splitting is a great challenge for future renewable energy conversion systems. Herein, Ni_2P nanosheet arrays directly grown on three-dimensional(3 D) Ni foam(Ni P/NF) are fabricated by hydrothermal treatment of metallic Ni foam with H_2O_2 solution and subsequent phosphidation with NaH_2PO_2. The Ni P/NF as electrocatalyst exhibits superior activities for both hydrogen evolution reaction(HER) and oxygen evolution reaction(OER). Most importantly, employing both as the cathode and anode for an alkaline water electrolyzer, Ni P/NF only requires a cell voltage of 1.63 V to reach a current density of 10 mV cm~(-2), together with stronger durability. Preliminary catalytic information suggests that the tailored 3 D superstructure and integrated electrode configurations afford improved active sties and enhanced electron/mass transfer,responding for the outstanding activity and stability.     

Porous nanostructured ZnCo_2O_4 derived from MOF-74:High-performance anode materials for lithium ion batteries

Nanostructured metal oxides derived from metal organic frameworks have been shown to be promising materials for application in high energy density lithium ion batteries. In this work, porous nanostructured ZnCo_2O_4 and Co_3O_4 were synthesized by a facile and cost-effective approach via the calcination of MOF-74 precursors and tested as anode materials for lithium ion batteries. Compared with Co_3O_4, the electrochemical properties of the obtained porous nanostructured ZnCo_2O_4 exhibit higher specific capacity, more excellent cycling stability and better rate capability. It demonstrates a reversible capacity of 1243.2 m Ah/g after 80 cycles at 100 m A/g and an excellent rate performance with high average discharge specific capacities of 1586.8, 994.6, 759.6 and 509.2 m Ah/g at 200, 400, 600 and 800 m A/g, respectively.The satisfactory electrochemical performances suggest that this porous nanostructured ZnCo_2O_4 is potentially promising for application as an efficient anode material for lithium ion batteries.     

Characterizations of nickel mesh and nickel foam current collectors for supercapacitor application

Nickel (Ni) current collectors having a three-dimensional and porous structure are considered attractive contestants for high-efficiency supercapacitors. Therefore, Ni current collectors have a unique architecture and outstanding electrochemical properties. This study reports the effect of electrochemical characterizations on the electrochemical behavior and physical properties of Ni mesh and Ni foam. Cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) are used to examine the electrochemical properties and life span of the Ni mesh and Ni foam as a current collector in a supercapacitor application. Structural and microstructural characterizations are performed to verify the formation of an oxide layer after 1000 cycles of CV analysis. Results show that Ni foam can increase the yield electrochemical performance of the supercapacitor. Ni foam present better efficiency (35 F g⁻¹) compared to the Ni mesh (12 F g⁻¹) at 10 mV s⁻¹ scan rate by using 2 mg imaginary mass of active material. This result shows that Ni foam has good electrochemical performance and reversibility, higher pseudocapacitance, weaker polarization, and enhance rotating performance as to Ni mesh. The porous structure of Ni foam is in control for improving of the electrochemical properties, therefore, the electrochemical region was increased and shortened ion diffusion. Structural analysis shows that Ni mesh and Ni foam are oxidized after the electrochemical analysis and transformed to nickel oxide hydroxide (NiOOH). Higher specific surface area between the electrode and electrolyte leads to excellent electrochemical and pseudocapacitive performance of the Ni foam compared to the Ni mesh, even if the materials of current collectors are the same. Hence, the physical structure of the current collectors have a critical part in improving the energy density of the supercapacitor.     

以泡沫镍载NiCo2O4纳米线阵列为阴极催化剂的Al-H2O2半燃料电池

研究了以泡沫镍载NiCo2O4纳米线阵列为阴极催化剂的Al-H2O2半燃料电池的性能. 以无模板生长法制备了泡沫镍载NiCo2O4纳米线阵列阴极材料, SEM测定结果表明, NiCo2O4纳米线几乎垂直于泡沫镍载体表面生长. 以电压和功率密度-电流密度曲线研究了H2O2浓度、电解液流速和温度对电池性能的影响, 结果显示, 以铝片为阳极, 0.6 mol/L H2O2为氧化剂的电池的开路电压约为1.40 V; 在室温和57 ℃下, 电流密度为98和172 mA/cm2时, 最大功率密度分别达到79和120 mW/cm2.  在5000 s的测试时间内, 0.70 V的恒电流密度和75 mA/cm2 的恒电压值几乎为一常数, 这表明以泡沫镍载NiCo2O4纳米线阵列为催化剂电还原H2O2具有很好的活性、稳定性和传质性能.     

NiCo2O4纳米线对 H2O2电还原的催化性能

以无模板生长法制备了泡沫镍载NiCo2O4纳米线正极材料, XRD和SEM表征结果表明, 所得材料为NiCo2O4纳米线, 以循环伏安法和计时电流法研究了泡沫镍载NiCo2O4纳米线对H2O2电还原的催化性能. 结果显示, 在0.4 mol/L H2O2 和 3.0 mol/L NaOH 溶液中, 当电压为-0.4 V(vs. Ag/AgCl)时, 循环伏安的电流密度达到125 mA/cm2; 当电压为-0.2, -0.3和 -0.4 V 时, 在30 min 的测试时间内, 计时电流密度几乎均为一常数, 表明以泡沫镍载NiCo2O4纳米线为催化剂电还原H2O2具有很高的活性和很好的稳定性.     

Ni(OH)2修饰的三聚氰胺泡沫用于可压缩超级电容器电极

通过化学镀和电化学镀的方法制备了一种Ni(OH)₂电化学活性材料修饰三聚氰胺泡沫(MF)可压缩骨架的超级电容器电极材料MF/Ni(OH)₂。MF/Ni(OH)₂可压缩电极材料表现出最佳的电容性能,例如循环稳定性(即使在40 mA/cm^-3的电流密度下经过2000次充放电循环后,可压缩电极仍能保持90.63%的初始电容)和可压缩稳定性(即使在压缩率为50%时,仍具有97.88%的电容保持率)。层状可压缩超级电容器由MF/Ni(OH)₂弹性材料作为阳极,镍/碳(Ni/C)为阴极以及实验室中常用的滤纸作隔膜材料组成。这种超级电容器装置在不同的压缩下表现出良好的电化学性能和优异的压缩稳定性。最后,使用可压缩的超级电容器来点亮LED灯,以展示其在柔性电子设备中的应用。这些优化的电化学和机械性能表明MF/Ni(OH)₂可作为可压缩超级电容器的应用中的候选电极。     

Growth of single-crystalline Ni and Co nanowires via electrochemical deposition and their magnetic properties

Single-crystalline Ni nanowires have been successfully fabricated with anodic aluminum oxide as template by electrodeposition. Structural characterization (X-ray diffraction, XRD, and high-resolution transmission electron microscopy, HRTEM) shows that the single-crystalline Ni nanowire has a preferred orientation along the [220] direction. The effects of electrochemical deposition conditions on the structure of Ni nanowires are systematically studied to investigate the growth mechanism. Possible reasons for the growth of the single-crystalline Ni nanowires were discussed on the basis of electrochemistry and thermodynamics. These single-crystalline Ni nanowires have exhibited excellent magnetic properties (large anisotropy, large coercivity, and high remanence). By a similar process, single-crystalline Co nanowires with hexagonal close-packed (hcp) structure were achieved, also having large anisotropy, large coercivity (1.8 kOe), and high remanence ratio (80.8%).     

Electrochemical Preparation of Polypyrrole/Graphene Films on Titanium Mesh as Active Materials for Supercapacitors

Films of polypyrrole/graphene on titanium mesh were prepared by electrochemical reduction of the fresh dried foam films of graphene oxide followed by an electrochemical polymerization of pyrrole. The as-obtained composite had highly surface area, conductivity, and could be used as the electrode for supercapacitors, especially directly used as the active materials in free of binders while the Ti mesh worked as the collector. Plenty of polypyrrole nanoparticles formed on the surface of reduced graphene film, and some fiber-like aggregates could be formed during the polymerization, which worked as the material for pseudo-capacitance. The specific capacitance of the supercapacitor reached 400 F/g and showed high stability with retaining capacitance of 82% after 5000 cycles, indicating that the nanocomposite is a suitable active material for supercapacitors.     

有序介孔碳/石墨烯/镍泡沫的制备及其对多巴胺的高灵敏度和高选择性检测

柔性生物传感器在可穿戴电子设备中有着广泛的应用前景. 为了获得柔性电化学多巴胺传感器,作者在本工作中首先在镍泡沫表面通过化学气相沉积生长石墨烯,随后通过高温碳化嵌段共聚物与酚醛树脂在石墨烯表面共组装形成的薄膜制备了有序介孔碳/石墨烯/镍泡沫（OMC/G/Ni）复合材料. 其中,镍泡沫可以为复合材料提供具有高导电性和良好柔韧性的金属骨架,而具有垂直排列介孔阵列的有序介孔碳层为复合材料提供了高的电活性表面积,且有利于活性位点的暴露. 值得注意的是,夹在有序介孔碳层和镍泡沫之间的石墨烯极大地增强了各组分之间的相容性,有利于进一步提升复合材料的电化学性能. 作为电化学传感器中的工作电极,OMC/G/Ni体现出优异的多巴胺检测能力. 不但具有宽的线性检测范围（0.05 ~ 58.75 μmol·L^-1）和低检测限（0.019 μmol·L^-1）,还具有良好的选择性、重现性和稳定性. 此外,OMC/G/Ni在弯曲状态下依旧能够保持对多巴胺的高检测能力,证明了其在柔性生物传感器中的应用潜力.     

A First-principles Study on the Gas Sensitivity of Metal-loaded Graphene with an Atomic Vacancy to O_2

In this work, adsorption energies, geometrical and electronic structures for adsorption systems of O_2 at metal-loaded graphene(M-Gra) and metal-loaded defective graphene(M-D-Gra)(M = Ni, Pd, Pt and Al) surfaces are studied using a GGA-PW91 method. Calculated results show that loaded M make the interaction between O_2 and the graphene surface change from physical to chemical adsorptions, band gaps of M-Gra systems after the O_2 adsorption change, and the Ni-loaded Gra has the highest sensitivity to O_2. For O_2-M-D-Gra systems, interactions between O_2 and the M-D-Gra surfaces are chemical, similar to the O_2-M-Gra systems, and loaded Pt and Al have the strongest effect on the sensitivity of D-Gra to O_2. The M loads at the perfect Gra and D-Gra surfaces make the interactions between O_2 and the surfaces have obvious charge transfer. This work would provide a valuable guidance on the gas sensitivity study of graphene to O_2.     

负载型纳米ZrO_2/Al_2O_3复合载体的制备和表征及其Ni/ZrO_2/Al_2O_3催化性能的研究

以大孔Al2O3为基载体,采用沉积-沉淀法和溶胶-沉积法制备了负载型纳米ZrO2/Al2O3复合载体.用XRD、TEM和比表面与孔径测定等手段对载体进行了表征.结果表明,负载型纳米ZrO2/Al2O3复合载体具有较大的比表面积和适宜的孔径分布,纳米ZrO2在载体上呈单层均匀分布.以CH4-CO2重整制合成气为探针反应,考察了Ni/ZrO2/Al2O3催化剂的活性和选择性.     

Functionalized graphene foam as electrode for improved electrochemical storage

We report on a non-covalent functionalization of graphene foam (GF) synthesized via chemical vapour deposition (CVD). The GF was treated with pyrene carboxylic acid (PCA) which acted as a source of oxygen and/or hydroxyl groups attached to the surface of the graphene foam for its electrochemical performance improvement. The modified graphene surface enabled a high pseudocapacitive effect on the GF. A specific capacitance of 133.3 F g^?1, power density ～ 145.3 kW kg^?1 and energy density ～ 4.7 W h kg^?1 were achieved based on the functionalized foam in 6 M KOH aqueous electrolyte. The results suggest that non-covalent functionalization might be an effective approach to overcome the restacking problem associated with graphene electrodes and also signify the importance of surface functionalities in graphene-based electrode materials.     

石墨烯基纤维电容器的可控制备及应用

超级电容器又名电化学电容器,是一种绿色储能器件。 超级电容器的研究,从根本上讲是寻找比表面积大且可以被充分利用的电极材料。 石墨烯作为sp²杂化碳质材料的基元单位,具有独特的二维结构和优异的物化特性,使得其在超级电容器领域具有巨大的应用潜力,其中石墨烯纤维超级电容器受到了研究工作者越来越广泛的关注。 本文通过对一维石墨烯纤维的自组装以及与制备材料的共组装来作为超级电容器的电极材料,对其可控制备进行了系统的归纳和总结,可控构建独特的电极材料,使其性能得以优化,组装出高性能的超级电容器,并对相关领域的发展趋势做了展望。     

Three‐Dimensional NiMoO4 Nanosheets Supported on a Carbon Fibers@Pre‐Treated Ni Foam (CF@PNF) Substrate as Advanced Electrodes for Asymmetric Supercapacitors

Herein, we report a nanoarchitectured nickel molybdate/carbon fibers@pre‐treated Ni foam (NiMoO₄/CF@PNF) electrode for supercapacitors. The synthesis of NiMoO₄/CF@PNF mainly consists of a direct chemical vapor deposition (CVD) growth of dense carbon fibers (CFs) onto pre‐treated Ni foam (PNF) as the substrate, followed by in situ growth of NiMoO₄ nanosheets (NSs) on the CF@PNF substrate by means of a hydrothermal process. The NiMoO₄/CF@PNF electrode exhibits a high areal capacitance (5.14 F cm^?2 at 4 mA cm^?2) and excellent cycling stability (97 % capacitance retention after 2000 cycles at 10 mA cm^?2). Furthermore, we have successfully assembled NiMoO₄ NSs//activated carbon (AC) asymmetric supercapacitors, which can achieve an energy density of 45.6 Wh kg^?1 at 674 W kg^?1, and excellent stability with 93 % capacitance retention after 2000 cycles at 5 mA cm^?2. These superior properties hold great promise for energy‐storage applications.     

Na0.11WO3 nanoflake arrays grown on Ni foam for high-performance supercapacitor

Journal of Solid State Electrochemistry - Via a facile one-pot hydrothermal method, nanoflake arrays constructed by Na0.11WO3 and amorphous NiO or Ni (OH)2 were successfully grown on Ni foam (NF)...     

石墨烯对Ni（OH）2超级电容器材料电化学行为的影响

研究了氧化缺陷石墨烯对Ni(OH)2电化学性能的增强作用.实验上,由恒电位沉积法在石墨烯基底上制备Ni(OH)2纳米粒子/石墨烯复合材料.TEM观察和电化学测试表明,Ni(OH)2纳米粒子均匀地分散在石墨烯基底上,其粒径为5.0±0.5 nm,体系的质量比电容值为1928 F.g-1.量化计算表明,上述复合材料乃是通过Ni(OH)2与石墨烯表面功能基团的强化学作用相结合而导电的,电子则是自石墨烯基底经氧化缺陷向Ni(OH)2传递,导致Ni(OH)2带负电,从而形成Ni(OH)2纳米粒子的单向导电行为.     

Design of hierarchical double-layer NiCo/NiMn-layered double hydroxide nanosheet arrays on Ni foam as electrodes for supercapacitors

Reasonably designing the structure of composite materials and effectively increasing electroactive sites of electrode materials are considered as the promising approaches to enhance the electrochemical performance for supercapacitors. Herein, a double-layer layered double hydroxide nanosheet array grown on Ni foams is constructed through a facile two-step hydrothermal method. The as-prepared double-layer electrode materials including Ni, Co, and Mn elements possess large surface area and porosity; thus, it can increase the contact between electrolytes and the electrode materials, which leads to an increase in electroactive sites and high electrochemical performance. The double-layer electrode shows a high capacitance performance (2950 F/g at 1 A/g) and superior cycling stability (79% retention after 10,000 cycles at 10 A/g). In addition, the asymmetric NiCo/NiMn-LDHs//AC device is fabricated and manifests good capacity with excellent cyclic stability of 82.2% after 10,000 cycles.