Influence of pulse plating conditions on the structure and properties of pure and composite nickel nanocrystalline coatings

An additive-free Watts type bath containing micron- and nano-SiC particles (1 μm and 20 nm respectively), as well as ultrafine-WC particles (200 nm), was used for the production of pure Ni and nickel matrix composite electrocoatings under both direct and pulse current conditions. Moreover, nickel nanocrystalline deposits were obtained from a Watts type bath containing small amounts of 2-butyne-1,4-diol, in order to investigate the combined advantages of additives and pulse technique on the properties of the deposits. The influence of the variable electrolysis parameters, the particle size and the organic additive concentration on the surface morphology, the structure and properties of the deposits were discussed. It has been proved that the application of pulse electrodeposition affects drastically the structural characteristics and properties of the deposits and under well-defined conditions could lead to the preparation of nanostructured materials with improved mechanical properties. Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 6, pp. 802–811. The text was submitted by the authors in English.     

纳米二氧化硅对镍电沉积影响及在复合镀层中的化学键合状态

用线性扫描伏安法和电位阶跃法研究了n-SiO2/Ni复合电刷镀体系的电化学响应,探讨了纳米颗粒的影响;用X射线光电子谱研究了复合镀层中n-SiO2/Ni颗粒表面与基质金属间的相互作用．结果表明纳米颗粒使金属沉积过电位显著降低,电流效率、金属成核率及晶体生长速度增加,纳米颗粒对金属镍电结晶有明显的催化效应;n-SiO2/Ni表面氧的不饱和化学键与表面扩散过程中吸附态金属Ni原子键合形成Ni-O键,纳米颗粒与基质镍以化学键方式结合．     

Microstructure of Nickel Aluminides Formed in Situ in Aluminium Matrix Composites

Nickel aluminides formed in situ in aluminium matrix composites due to the interaction between nickel powder and the matrix were examined. The composite materials were obtained from mixtures of nickel powder and aluminium powder by hot pressing in vacuum in the temperature range of 500–640°C. Depending on hot pressing parameters, the morphology of nickel aluminide particles was layered or homogenous, and their size for the same precursor powder was growing as the pressing temperature increased. XRD, SEM, TEM and EDS characterization methods were used for the microstructure investigation.     

电化学阴极沉积制备氧化镍/碳纳米管复合电极的准电容特性

A novel type of composite electrode based on multiwalled carbon nanotubes coated with nano nickel oxide particles has been used in supercapacitors. Nickel oxide cathodically deposited from Ni(NO3)2 solution with carbon nanotubes as the matrix exhibited large pseudocapacitance of 25F/g in 6 mol/L KOH. The morphology of composites was examined by scanning electron microscope (SEM). To characterize the CNTs/nickel oxide composite electrode, a charge discharge cycling test for measuring specific capacitance, cyclic voltammetry, and ac impedance test is executed. The nickel oxide composite exhibiting excellent pseudocapacitive behavior(i.e.high reversibility, high specific capacitance, and low self discharge rate) has been demonstrated to be a potential candidate for the application of electrochemical supercapacitors.     

Composite Nickel–Polystyrene Electrodes: Surface State of Nickel and Ion Transfer

Nickel–polystyrene composite materials produced by the chemical deposition of nickel on polystyrene beads exhibit high conductivity at a nickel concentration of less than one percent by volume. These composites exhibit a higher sensitivity to Ni²⁺ions (RT/zF) than bulk nickel. According to X-ray photoelectron spectroscopy data, the increased sensitivity of nickel–polystyrene electrodes is due to the formation of a modified surface layer of the composite containing a nickel–polystyrene complex and to direct Ni²⁺ion exchange at the interface between the solution and this layer.     

碳氮复合材料负载镍甲醇羰基化催化剂的研究

通过碳化由偏氯乙烯和丙烯腈悬浮共聚得到的前体,制得碳氮复合材料,将其负载金属镍后即得气相甲醇羰基化反应的催化剂。分别采用扫描电镜(SEM)、氮气吸附、XPS、电子探针(EPMA)等方法对该材料及由其制得的催化剂进行表征,证明该催化剂中的镍呈高度分散的纳米粒子状态。采用固定床反应器对该催化剂进行催化性能测试,结果表明该催化剂在较低金属镍负载量及较温和的条件下即可具有较好的催化性能。该催化剂的最佳镍负载量为1.5%左右。     

电感耦合等离子体质谱法(ICP-MS)测定镍钴锰三元氢氧化物中铅

研究了用电感耦合等离子体质谱法（ICP-MS）测定镍钴锰三元素氢氧化物中铅含量的测定方法。选择了仪器的最佳测量条件、元素测定的质量数,进行了基体元素的干扰等实验。方法测定结果准确、可靠,测定下限小于0.00005%,样品加标回收率在99.2%~101.0%。方法的建立为控制镍钴锰三元素氢氧化物中铅提供了检测依据。     

无电镀镍复合镀层耐蚀性质研究

研究无电镀镍镀层加入钻石微粒或PTFE微粒的均匀分散相 ,所得之复合镀层在 3.5%NaCl水溶液中的电化学分析 ,浸渍试验与临雾试验 ,皆显示复合镀层之耐蚀性低于不含微粒之无电镀镍镀层 .由SEM ,AES ,XRD ,EPMA分析镀层微观组成 ,复合镀层之磷含量分布呈差异性变化 ,磷量较多区域为微阴极 ,磷量较少区域为微阳极 ,复合镀层存在众多微电池组合 ,容易引起电化学伽凡尼腐蚀 ,造成复合镀层耐蚀性降低 ,当镀层微粒含量增加时 ,微粒的惰性保护效果超过微电池效应 ,复合镀层的耐蚀性质才能提高     

Electrospun Nickel Oxide Hollow Nanostructured Fibers

The citric acid/nickel acetate composite hollow fibers were prepared by using sol-gel processing and co-electrospinning technique. The polycrystalline NiO hollow nanostructured fibers were prepared after calcination. The obtained hollow nanostructured fibers made up of 17～25 nm nanocrystals were about 150 nm to several micrometers in outer diameter. The hollow NiO nanostructured fibers have been characterized by TG, DSC, SEM, FTIR, and XRD techniques. The results showed that the morphology of NiO hollow fibers was obviously influenced by the calcination temperature.     

Electroanalytical Detection of n‐Butylamine at a Nickel/Carbon Nanotube Composite

We report the electroanalytical detection of n‐butylamine at a nickel/carbon nanotube (Ni/CNT) composite. Scanning Electron Microscopy (SEM) characterisation of the composite demonstrated that it consisted of bulk nickel particles ca. 2 μm in diameter entangled in CNT bundles. The spontaneous formation of Ni(OH)₂ was optimised, and comparison with a 3 mm nickel electrode showed that ca. 4 μg of the Ni/CNT composite cast on a 3 mm GC electrode possessed bulk nickel characteristics while also having higher activity and higher sensitivity towards the electrochemical detection of n‐butylamine. However, the Ni/CNT composite showed no response to ammonia, in contrast to the macro‐nickel‐electrode.     

The Chemisorptive Properties of Nickel Borides

The chemisorptive properties of the nickel borides have been studied with temperature programmed desorption of H₂ and CO. The TPD chromatograms of H₂ show two major peaks at 150°C and 300°C for the P-1 and P-2W nickel borides and a major peak at 150°C for the DBNi and CrP-1 nickel borides. Not all hydrogen molecules are dissociatively adsorbed on surface nickel, some hydrogens diffuse and are absorbed into the matrix of the nickel borides. Except the Cr-promoted P-1(P-2W), the nickel borides do not exhibit the obvious chemisorptive capacity for CO. The Cr-promoted nickel borides, on the other hand, not only have the obvious uptake capacity for CO but also have the good activity for CO dissociation.     

Nickel oxide coated on ultrasonically pretreated carbon nanotubes for supercapacitor

Nickel oxide/carbon nanotubes (NiO/CNTs) composite materials for supercapacitor are prepared by chemically depositing nickel hydroxide onto carbon nanotubes pretreated by ultrasonication and followed by thermal annealing at 300 °C. A series of NiO/CNTs composites with different weight ratios of nickel oxide versus carbon nanotubes are synthesized via the same route. The high-resolution TEM and SEM results show that a lot of nicks, which favored the nucleation of the nickel hydroxide formed on the outer walls of carbon nanotubes due to ultrasonic cavitations, and then nickel oxide coated uniformly on the outer surface of the individual carbon nanotubes. The NiO/CNTs electrode presents a maximum specific capacitance of 523 F/g as well as a good cycle life during 1,000 cycles in 6 M KOH electrolyte. The good electrochemical characteristics of NiO/CNTs composite can be attributed to the three-dimensionally interconnected nanotubular structure with a thin film of electroactive materials.     

Nickel Coated Graphite Microparticle Based Electrodes for Carbon Dioxide Reduction in MonoethanolamineMedium

A composite electrode that contains home-made nickel coated carbon micro-particles as active materials and epoxy binder has been prepared. The surface morphology, elemental composition and size distribution of microparticles were investigated using SEM, EDS, AAS, micro Raman spectroscopy and appropriate seizer apparatus. The prepared micro-particles appeared monodispers with 33 μm most numerous particle size diameter and with 10.1 w/w % Ni content. Conventional electrochemical methods like impedance spectroscopy and voltammetry as well as scanning electrochemical microscopy (SECM) were used for investigation the properties of the composite electrodes. It has been proved that the electrode can be well used for electro-catalytic reduction of CO₂ directly in aqueous mono-ethanol amine (MEA) solution that frequently are applied for capturing it from power plant flue gases. SECM measurements showed that presence of dissolved CO₂ hinders the hydrogen evolution in aqueous MEA solution.     

硫化镍/三维网络石墨烯复合材料制备及其在高性能超级电容器的应用研究

本文在泡沫镍上生长三维网络状结构的石墨烯（3DG）,以此为模板合成石墨烯复合电极并将其应用于超级电容器. 采用一步水热法在3DG上合成得到Ni₃S₂纳米棒结构（Ni₃S₂/3DG）. 通过TEM、XRD、SEM和拉曼光谱等手段表征对Ni₃S₂/3DG复合材料的形态与结构进行表征. 电化学测试表明,Ni₃S₂/3DG复合材料具有高的比电容（在扫速为5 mV·s^-1下,具有1825.3 F·g^-1的比容量）和放电电容（在电流密度10 mA下电容高达516.7 F·g^-1）. 此外,在电流密度20 mA下具有良好的循环性能（循环1000周后仍能保留约100%的初始电容）. 本工作为得到高能量密度和良好的长期稳定性的复合材料提供了参考.     

超细氢氧化亚镍的溶胶凝胶法制备及其准电容特性

以聚乙二醇为抑制剂,采用溶胶凝胶法制备了粒径小于200 nm且具有链珠状特殊形态的超细氢氧化亚镍电极材料.伏安特性测试和电化学阻抗测试表明在氢氧化亚镍中掺加适量碳纳米管可以显著改善电极材料的容量特性和阻抗特性,其中碳纳米管质量分数为20％的复合电极其比电容量可以达到320 F&;#8226;g^－1.采用复合电极作为正极,活性炭电极作为负极组成的复合型电化学电容器最大工作电压可以达到1.6 V,具有良好的容量特性和大电流放电特性.恒流充放电测试证明复合型电化学电容器具有高能量密度及高功率放电特性,电容器的峰值功率密度为8.6 W&;#8226;g^－1.当以0.88 W&;#8226;g^－1功率放电时,电容器能量密度可达20.11 W&;#8226;h&;#8226;kg^－1, 当采用3.46 W&;#8226;g^－1的高功率进行放电时,复合型电容器的能量密度仍然能够达到11.11 W&;#8226;h&;#8226;kg^－1.     

Nickel Hydroxide Supercapacitor with a Theoretical Capacitance and High Rate Capability Based on Hollow Dendritic 3D‐Nickel Current Collectors

A straightforward way to attain the theoretical capacitance and high rate capability of nickel hydroxide supercapacitors, by utilizing a mesoporous hollow dendritic three‐dimensional‐nickel (3D‐Ni) current collector is proposed. A facile electrodeposition method employing a hydrogen bubble template was chosen for rapid fabrication of the dendritic 3D‐nickel structure. After nickel hydroxide was deposited on the hollow 3D‐nickel current collector, it exhibited a highest capacitance of 3637 F g⁻¹ at a current density of 1 A g⁻¹, and retained 97 % of capacitance at a high current density of 100 A g⁻¹ with a cycle stability of over 80 % after 10 000 cycles. The enhanced performance could be attributed to the large surface area and high conductivity of the moss‐like dendritic 3D‐Ni current collector, which allowed direct contact between the active materials and the current collector, and reduced diffusion resistance between the surface of the active materials and the electrolyte. These results not only confirmed a facile fabrication method for high‐performance 3D metal nanostructures, but also offer a promising solution for state‐of‐the‐art energy storage systems.     

网孔状NiO电极制备及其电容特性

以硫酸镍和尿素作原料,六偏磷酸钠为表面活性剂,由水热法制备前驱体,经400℃煅烧即得网孔状结构的NiO.XRD、SEM和恒流充放电分析测试样品的相结构、微观形貌和电容特性,考察不同水热温度对合成产物电化学性能的影响.结果表明：当镍与尿素摩尔比为1∶4时,由140℃水热合成前驱体,经400℃煅烧得到的氧化镍性能较好.在2...     

纳米陶瓷颗粒的电催化效应及其在复合刷镀层中的化学状态

采用循环伏安法和电位阶跃法研究了nano-Al₂O₃ / Ni复合电刷镀体系的电化学响应，探讨了纳米颗粒对复合电沉积的影响；用X射线光电子谱研究了复合镀层中nano-Al₂O₃颗粒与基质金属之间的相互作用。结果表明纳米颗粒能使金属沉积过电位显著降低，电流效率、金属成核率及晶体生长速度增加，从而对金属镍的电结晶表现出明显的催化效应；在金属镍电结晶过程中，部分到达阴极附近的nano-Al₂O₃颗粒被电极表面捕获。金属生长面上的吸附态镍原子到达纳米颗粒与电极表面接触处，与该处纳米颗粒表面的不饱和氧原子形成Ni-O化学键，纳米颗粒与基质镍以化学键形式结合。纳米颗粒与电极表面的结合区域成为新的成核或生长中心，在随后的刷镀过程中纳米颗粒逐渐被电沉积的金属镍包埋，从而形成复合镀层。     

Functional Models of the Nickel Pincer Nucleotide Cofactor of Lactate Racemase

A novel nickel pincer cofactor was recently discovered in lactate racemase. Reported here are three synthetic nickel pincer complexes that are both structural and functional models of the pincer cofactor in lactate racemase. DFT computations suggest the ipso‐carbon atom of the pyridinium pincer ligands act as a hydride acceptor for lactate isomerization, whereas an organometallic pathway involving nickel‐mediated β‐hydride elimination is less favored.     

Functional Porous Carbon/Nickel Oxide Nanocomposites as Binder‐Free Electrodes for Supercapacitors

High‐surface‐area, guava‐leaf‐derived, heteroatom‐containing activated carbon (GHAC) materials were synthesized by means of a facile chemical activation method with KOH as activating agent and exploited as catalyst supports to disperse nickel oxide (NiO) nanocrystals (average size (2.0±0.1) nm) through a hydrothermal process. The textural and structural properties of these GHAC/NiO nanocomposites were characterized by various physicochemical techniques, namely, field‐emission SEM, high‐resolution TEM, elemental analysis, X‐ray diffraction, X‐ray photoelectron spectroscopy, thermogravimetric analysis, and Raman spectroscopy. The as‐synthesized GHAC/NiO nanocomposites were employed as binder‐free electrodes, which exhibited high specific capacitance (up to 461 F g^?1 at a current density of 2.3 A g^?1) and remarkable cycling stability, which may be attributed to the unique properties of GHAC and excellent electrochemical activity of the highly dispersed NiO nanocrystals.