Morphologically controlled preparation of CuO nanostructures under ultrasound irradiation and their evaluation as pseudocapacitor materials

Various morphologies of copper oxide (CuO) nanostructures have been synthesized by controlling the reaction parameters in a sonochemical assisted method without using any templates or surfactants. The effect of reaction parameters including molar ratio of the reactants, reaction temperature, ultrasound exposure time, and annealing temperature on the composition and morphology of the product(s) has been investigated. The prepared samples have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDAX), and thermogravimetric analysis (TGA). It has been found that Cu₂(OH)₃NO₃ nanoplatelets are achieved in mild conditions which can be then converted to various morphologies of CuO nanostructures by either using high concentrations of OH⁻ (formation of nanorods), prolonging sonication irradiation (nanoparticles), or thermal treatment (nanospheres). Application of the prepared CuO nanostructures was evaluated as supercapacitive material in 1 M Na₂SO₄ solution using cyclic voltammetry (CV) in different potential scan rates ranging from 5 to 100 mV s⁻¹. The specific capacitance has been calculated using CV curves. It has been found that the pseudocapacitor performance of CuO can be tuned via employing morphologically controlled samples. Accordingly, the prolonged sonicated sample (nanoparticles) showed the high specific capacitance of 158 F.g⁻¹.     

溶胶凝胶方法制备纳米氧化钌的超电容特性

采用溶胶凝胶方法制备了具有纳米尺度和多孔特征的氧化钌超电容器活性材料,探讨了烧结温度对电极材料的晶体结构,颗粒大小及电化学特性的影响．结合热失重分析、扫描电镜、循环伏安测试等方法探讨了溶胶凝胶法制备钌产物的组成及在高温条件下发生的分解过程和相应产物．钌氧化物材料经过210℃烧结处理后具有541 F／g的电化学容量,由其组成的超电容器具有67 J/g的能量密度．采用高导电乙炔黑作为载体制备了氧化钌／乙炔黑复合电极材料,当乙炔黑含量为10％时,电极材料的比容量达到802 F/g,采用该电极材料组成的电化学电容器具有100 J／g的能量密度且表现了良好的高功率放电特性．     

Preparation and Pseudo-capacitance Performance of NiCo2O4 Nanosheets

Ternary nickel cobaltite(NiCo₂O₄), as a promising electrode material for supercapacitors, has attracted increasing attention for its excellent electrochemical properties. In this study, novel NiCo₂O₄ nanosheets were rationally designed and prepared using dealloying process, followed by an oxidation treatment. The as-prepared sample was characterized by microstructural and electrochemical techniques in view of its possible application in supercapacitors. The as-prepared sample exhibited high specific capacitance and excellent durability. The specific capacitance reached 663 F/g at 1 A/g and the rate capacitance high up to 73.6% when the current density increased from 1 A/g to 20 A/g. After 5000 cycles of galvanostatic charge-discharge durability test at 4 A/g, the capacity retention rate was 82.1%. The results indicate that versatile dealloying can be used to prepare robust electrode for supercapacitor application.     

硫酸溶液中电化学改性石墨电极对Fe3+/Fe2+的电催化性能与准电容特性

通过循环伏安(CV)、恒电流充放电和电化学阻抗谱(EIS)等测试方法,研究了电化学改性石墨电极对硫酸溶液中Fe3+/Fe2+的电催化性能与准电容特性.结果表明:由于电化学改性石墨电极表面存在大量的含氧活性官能团,使其对Fe3+/Fe2+的氧化还原反应具有极高的电催化性能,并具有可逆反应过程特征.在含有0.5mo·lL-1Fe3++0.5mo·lL-1Fe2+的2.0mo·lL-1H2SO4溶液中,其表观面积比电容是不含铁离子硫酸溶液的1.808倍,达到2.157F·cm-2;同时,铁离子浓度的增大也能够进一步提高其电容量.Fe3+/Fe2+电对的加入增加了充放电时间,有效提高了电化学电容器(EC)的电容存储容量和高功率特性.电化学阻抗谱测试同样证实体系具有明显的电容特性.因此,可以利用电化学改性石墨电极表面的含氧活性官能团和溶液中Fe3+/Fe2+的氧化还原特性来共同储存和释放能量.     

氧化钌/活性炭超电容器复合电极的电化学行为

电化学超电容器作为一种新一代储能系统具有广泛的应用领域. 直流充放电、循环伏安以及交流阻抗等实验显示了本文制备的活性碳材料以及复合电极材料具有良好的电化学性能.活性碳材料的质量比容量为172 F•g－1,采用无定形RuO2与上述活性碳复合制成的新型电极材料具有359 F•g－1以上的比容量和良好的功率特性，并对上述材料的双电层电容和法拉第准电容等电化学特性进行了详细的讨论.     

含磷活性炭作为双电层电容器电极材料的电化学性能

采用磷酸活化和磷酸改性制备了不同种类的含磷活性炭,采用元素分析、X射线光电子能谱(XPS)和氮气吸附等手段分析了活性炭的元素含量、表面化学性质和孔隙结构,采用恒电流充放电、循环伏安和交流阻抗分别考察了活性炭在KOH和H₂SO₄电解质溶液中作为超级电容器电极材料的电化学性能,采用自由截距多元线性回归拟合统计分析研究了活性炭电极比电容量的影响因素,应用三电极体系分析了磷元素对活性炭电化学性能的影响机理。研究结果表明,活性炭掺杂的磷引入了赝电容,提高了活性炭电极的比电容量,磷元素含量为5.88%(w)的活性炭的比电容量在0.1 A·g^-1下达到185 F·g^-1。统计分析结果显示,活性炭的中孔有利于电解质离子向微孔内的扩散。在6 mol·L^-1 KOH电解质溶液中,孔径在1.10-1.61 nm、2.12-2.43nm及3.94-4.37 nm范围内是电解质离子在活性炭孔隙内部形成双电层的主要场所;在1 mol·L^-1 H₂SO₄电解质溶液中,孔径在0.67-0.72 nm范围内有利于双电层电容的形成。     

溶胶凝胶方法制备纳米氧化钌的超电容特性

A kind of ruthenium oxide with smaller particles and higher porosity was prepared by a sol-gel process with RuCl3·xH2O and NaHCO3 solution. Several details concerning this new material, including crystal structure,particle size as functions of the temperature, and electrochemical properties were also reported. The optimal annealing temperature was 210 ℃ and the powder annealed at this temperature had a rate capacitance of 541 F/g. In addition, the rate capacitance of the composite electrode reached 802 F/g after 10% carbon black was added, much higher than any previously reported value. High energy density supercapacitors were built with the newly discovered electrode material. Energy densities as high as 67 J/g were obtained based on the RuO2 ·xH2O alone. By introducing the highly porous carbon black into the electrode, energy densities great than 100 J/g could be achieved. The power density of the capacitor was enhanced significantly.     

电化学改性石墨电极在不同溶液中的准电容及电催化性能

通过循环电流阶跃方法制备电化学改性石墨电极(MGE), 用循环伏安(CV)法评价了MGE在酸性和中性溶液中的准电容特性, 并研究了其在HCl和HNO₃溶液中的电催化作用. 结果表明: 在酸性条件下, MGE在H₂SO₄溶液中具有佷好的准电容特性, 比电容高达1.730 F·cm^-2; 在HCl溶液中也具有很好的准电容特性, 且MGE对析氯反应具有一定的电催化活性(起始析氯电位负移238 mV), 使其电位窗变窄; 在HNO₃溶液中没有准电容特性, 而MGE对NO₃^-离子的还原反应具有极强的电催化能力. 当电介质由酸性变为中性时, 虽然其峰电流密度有所降低, 但电位窗大幅度增宽, 意味着MGE在中性体系中的能量密度比酸性体系会有较大的提高.