Electrochemical Degradation of Indigocarmine Dye at Ni/Graphite Modified Electrode in Aqueous Solution

Nickel Graphite modified electrode (Ni/GME) was prepared by electrochemical method and degradation of Indigocarmine (IC) dye was carried out. An investigation between the efficiency of degradation by graphite electrode and the Ni/graphite modified electrode has been carried out. The different effects of concentration, current density and temperature on the rate of degradation were studied. This study shows that the rate of the degradation is more for Ni doped modified graphite electrode. UV-Visible spectra before and after degradation of the dye solution were observed. The thin film formation of Ni or encapsulated in graphite rod is observed by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM & EDAX). The instantaneous current effectiveness values of different experimental conditions are evaluated. The anodic oxidation by Ni/ graphite modified electrode showed the complete degradation of aqueous solution indigocarmine, which is confirmed by UV-Visible and chemical oxygen demand (COD) measurements. The dye is converted into CO2, H2O and simpler inorganic salts. The results observed for reuse of modified electrodes indicate that the Ni/graphite modified electrode would be a promising anode for electrochemical degradation of indigocarmine. This method can be applied for the remediation of waste water containing organics, cost-effective and simple.

SnO_(2)-Au-PANI复合材料改性商用NH_(3)传感墨水及其性能研究

采用点胶印刷技术,以商用墨水(kz-sense-103)在棉布基底上考察电极指间距和电极对数对氨气(NH_(3))传感性能的影响,确定了指间距为1 mm、传感器性能最佳的6对叉指电极。研究了以SnO_(2)-Au-PANI复合物改性商用墨水获得的改性墨水的传感性能。结果表明:经改性墨水制备的传感器实际检测限可达到5×10^(-6)的NH_(3),性能远远优于商用墨水,且具有优异的时间、温度和湿度稳定性,并能够从H_(2)、CO、SO_(2)和NH_(3)中区分出NH_(3),表明该传感器墨水适合在日常及工业环境中对NH_(3)的监测应用。

Ni doped La_(0.6)Sr_(0.4)FeO_(3-δ) symmetrical electrode for solid oxide fuel cells

The conventional Ni cermet anode suffers from severe carbon deposition and sulfur poisoning when fossil fuels are used. Alternative anode materials are desired for high performance hydrocarbon fuel solid oxide fuel cells （SOFCs）. We report the rational design of a very active Ni doped La0.6Sr0.4FeO3‐δ（LSFN） electrode for hydrocarbon fuel SOFCs. Homogeneously dispersed Ni‐Fe alloy nanoparticles were in situ extruded onto the surface of the LSFN particles during the operation of the cell. Sym‐metric SOFC single cells were prepared by impregnating a LSFN precursor solution onto a YSZ （yt‐tria stabilized zirconia） monolithic cell with a subsequent heat treatment. The open circuit voltage of the LSFN symmetric cell reached 1.18 and 1.0 V in humidified C3H8 and CH4 at 750？？, respective‐ly. The peak power densities of the cells were 400 and 230 mW/cm2 in humidified C3H8 and CH4, respectively. The electrode showed good stability in long term testing, which revealed LSFN has good catalytic activity for hydrocarbon fuel oxidation.

Au-Cu-Ni合金的析出强化和润滑特性研究进展

Au基合金具有润湿性良好、电接触性稳定等优点,被广泛应用于电刷、绕组器件和导电滑环等滑动电接触材料,在信号传输系统中发挥着十分重要的作用。目前,传统的Au-Cu、Au-Mo、Au-Ni等二元系合金已不能满足实际需求,而Au-Cu-Ni三元系合金在时效过程中会发生有序强化,是潜力较大的新一代滑动电接触材料。概述了Au-Cu-Ni合金在析出相强化、析出规律和润滑改性等方面的研究进展,为滑动电接触材料的研究提供参考。

Temperature Effect on Hydrogen Evolution Reaction at Au Electrode

The temperature dependence of hydrogen evolution reaction （HER） at a quasi-single crystalline gold electrode in both 0.1 mol/L HCl04 and 0.1 mol/L KOH solutions was investigated by cyclic voltammetry. HER current displays a clear increase with reaction overpotential （η） and temperature from 278-333 K. In 0.1 mol/L HClO4 the Tafel slopes are found to increases slightly with temperature from 118 mV/dec to 146 mV/dec, while in 0.1 mol/L KOH it is ca. 153±15 mV/dec without clear temperature-dependent trend. The apparent activation energy （Ea） for HER at equilibrium potential is ca. 48 and 34 kJ/mol in 0.1 mol/L HC104 and 0.1 mol/L KOH, respectively. In acid solution, Ea decreases with increase in η, from Ea-37 kJ/mol （η=0.2 V） to 30 kJ/mol （η=0.35 V）. In contrast, in 0.1 mol/L KOH, Ea does not show obvious change with U. The pre-exponential factor （A） in 0.1 mol/L HC104 is ca. 1 order higher than that in 0.1 mol/L KOH. Toward more negative potential, in 0.1 mol/L HC104 A changes little with potential, while in 0.1 mol/L KOH it displays a monotonic increase with U. The change trends of the potential-dependent kinetic parameters for HER at Au electrode in 0.1 mol/L HClO4 and that in 0.1 mol/L KOH are discussed.

Ultrathin nanosheets of cobalt-nickel hydroxides hetero-structure via electrodeposition and precursor adjustment with excellent performance for supercapacitor

A homogeneous better-dispersed ultrathin nanosheets（ca. 5 nm） of cobalt-nickel layered double hydroxides（LDH） supported on nickel foam scaffold was synthesized using controllable electrodeposition approach for high efficiency electrode materials of new supercapacitor. The morphology and electrochemical performances of the samples can be controlled by adjusting the precursor ratio, i.e., Ni（OAc）2/Co（NO3）2 molar ratio in the electrodeposition approach. With the increase of this molar ratio, the electrochemical performances give a volcano trend. When the optimized molar ratio is 0.64/0.36, the hybrid delivered a high specific capacitance of 1587.5 F g-1 at a current density of 0.5 A g-1, with good rate capability（1155 F g-1 was retained even at 10 A g-1） and a robust recycle stability（remaining 91.5% after 1000 cycles at 5 A g-1）. The good performance could be attributed to the enlarged interlayer spacing, ultrathin nanosheets and synergistic effects between Co（OH）2 and Ni（OH）2. Furthermore, an asymmetric supercapacitor with a high energy density of 34.5 Wh kg-1 at 425 W kg-1 and excellent cycling stability of 85.4% after 5000 charge-discharge cycles at 2 A g-1 was fabricated. We believe that this fantabulous new electrode material would have encouraging applications in electrochemical energy storage and a wide readership.

Newly Design Porous/Sponge Red Phosphorus@Graphene and Highly Conductive Ni2P Electrode for Asymmetric Solid State Supercapacitive Device With Excellent Performance

Supercapacitors have attracted much attention in the field of electrochemical energy storage.However,material preparation,stability,performance as well as power density limit their applications in many fields.Herein,a sponge-like red phosphorus@graphene(rP@rGO)negative electrode and a Ni2P positive electrode were prepared using a simple one-step method.Both electrodes showed excellent performances(294 F g^−1 and 1526.6 F g^−1 for rP@rGO and Ni2P,respectively),which seem to be the highest among all rP@rGO-and Ni2P-based electrodes reported so far.The asymmetric solid-state supercapacitor was assembled by sandwiching a gel electrolyte-soaked cellulose paper between rP@rGO and Ni2P as the negative and positive electrodes.Compared to other asymmetric devices,the device,which attained a high operating window of up to 1.6 V,showed high energy and power density values of 41.66 and 1200 W kg−1,respectively.It also has an excellent cyclic stability up to 88%after various consecutive charge/discharge tests.Additionally,the device could power commercial light emitting diodes and fans for 30 s.So,the ease of the synthesis method and excellent performance of the prepared electrode materials mat have significant potential for energy storage applications.

Ni-Co过渡金属化合物在超级电容器中的研究进展

Ni-Co过渡金属化合物相对于二元过渡金属氧化物具有更高的导电率和电化学反应活性位点,作为电极材料展现出了良好的速率性能和循环稳定性。Ni-Co过渡金属氧化物具有较大的比电容,但导电率较低,速率性能较差,所以在Ni-Co过渡金属的基础上掺杂S元素或碳材料,有利于增加电化学反应位点和氧化还原反应,从而提高复合材料的导电性、稳定性。本文以Ni-Co过渡金属为主,对其三元氧化物、三元硫化物、三元氧化物与碳材料复合改性研究进行了综述,并对未来Ni-Co过渡金属发展进行了展望。

Electrochemical dechlorination of chloroform in neutral aqueous solution on palladium/foam-nickel and palladium/polymeric pyrrole film/foam-nickel electrodes

Electrochemical dechlorination of chloroform in neutral aqueous solution was investigated using palladium-loaded electrodes at ambient temperature. Palladium/foam-nickel （Pd/foam-Ni） and palladium/polymeric pyrrole film/foam-nickel （Pd/PPy/foam-Ni） composite electrodes which provided catalytic surface for reductive dechlorination of chloroform in aqueous solution were prepared using an electrodepositing method. Scanning electron microscope （SEM） micrographs showed that polymeric pyrrole film modified the electrode-surface characteristics and resulted in the uniform dispersion of needle-shaped palladium particles on foam-Ni supporting electrode. The experimental results of dechlorination indicated that the removal efficiency of chloroform and current efficiency in neutral aqueous solution on Pd/PPy/foam-Ni electrode could be up to 36.8% and 33.0% at dechlorination current of 0.1 mA and dechlorination time of 180 min, which is much higher than that of Pd/foam-Ni electrode.

Hierarchical coral-like FeNi(OH)_x/Ni via mild corrosion of nickel as an integrated electrode for efficient overall water splitting

Efficient,stable,and noble‐metal‐free electrocatalysts for both the oxygen evolution reaction and the hydrogen evolution reaction are highly imperative for the realization of low‐cost commercial water‐splitting electrolyzers.Herein,a cost‐effective and ecofriendly strategy is reported to fabricate coral‐like FeNi(OH)x/Ni as a bifunctional electrocatalyst for overall water splitting in alkaline media.With the assistance of mild corrosion of Ni by Fe(NO3)3,in situ generated FeNi(OH)x nanosheets are intimately attached on metallic coral‐like Ni.Integration of these nanosheets with the electrodeposited coral‐like Ni skeleton and the supermacroporous Ni foam substrate forms a binder‐free hierarchical electrode,which is beneficial for exposing catalytic active sites,accelerating mass transport,and facilitating the release of gaseous species.In 1.0 mol L^-1 KOH solution,a symmetric electrolyzer constructed with FeNi(OH)x/Ni as both the anode and the cathode exhibits an excellent activity with an applied potential difference of 1.52 V at 10 mA cm^-2,which is superior to that of an asymmetric electrolyzer constructed with the state‐of‐the‐art RuO2‐PtC couple(applied potential difference of 1.55 V at 10 mA cm^-2).This work contributes a facile and reliable strategy for manufacturing affordable,practical,and promising water‐splitting devices.

Effects of sputtering conditions on electrochemical behavior and physical properties of Ni-Mo alloy electrode

Sputtering method was used to prepare Ni-Mo alloy electrodes for hydrogen production in alkaline solution. The influences of the working pressure during deposition and the substrate temperature on the electrochemical behavior of electrode were characterized by steady-state polarization plot and Tafel polarization curve measurements. And the physical properties of electrodes were characterized by XRD, SEM, AFM and EDS. It is found that the overpotential is significantly influenced by the working pressure which affects critically the electrode surface morphology, and two Tafel regions are observed for each sample. The overpotential value does not change very much with the substrate temperature. The XRD results indicates that the electrodes should be considered nanocrystalline. Thornton model for the microstructure of sputter-deposited electrodes is referred to explain the observed microstructure change.

pH Effect on Oxidation of Hydrogen Peroxide on Au(111) Electrode in Alkaline Solutions

The hydrogen peroxide oxidation reaction (HPOOR) on Au(111) electrode in alkaline solutions with pH values ranging from 10 to 13 was examined systematically. HPOOR activity increased and the slope of the i-E curve decreased with increasing pH. HO2- is suggested to be the main reactive intermediate for HPOOR in alkaline media. The fast kinetics for HPOOR in alkaline solution is facilitated by the electrostatic interaction between the positively charged electrode and the reactive anions (i.e., HO2- and HO-), which increases the concentration of these reactants and the thermodynamic driving force for HO2- oxidation at the reaction plane.

煤焦-Ni复合物催化甲烷干重整及其反应后形成碳材料的电化学性能研究

甲烷干重整(DRM)反应能够将CH_(4)和CO_(2)两种温室气体转化为合成气,具有突出的环境和经济效益。但DRM反应过程的高温条件和产出的积炭易造成Ni等金属催化剂的失活,限制了其在工业上的应用。中低温煤热解半焦(简称“煤焦”)具有作为高效Ni基催化剂载体的良好潜力。为了提升DRM反应性能并促进煤焦利用,设计并制备了一种煤焦-Ni复合物,以K_(2)CO_(3)为助剂,考察了DRM反应性能、煤焦-Ni复合物在反应后形成碳材料的表面结构特征及其用作超级电容器电极材料的性能。研究发现,当m(煤焦):m(K_(2)CO_(3)):m(Ni)=1.00:1.00:0.05、DRM反应温度为850℃时,CH_(4)和CO_(2)初始转化率分别达71%和72%。优化反应条件(催化剂的Ni负载量、反应温度和反应时间)后,以煤焦-Ni复合物在反应后形成的碳材料为超级电容器电极材料可表现出优良的电化学性能,其中,CC-2在扫描速率为5 mV/s时,比电容为136 F/g;在电流密度为1 A/g时,比电容为143 F/g。本研究为DRM和煤焦的协同转化利用、反应后碳材料(反应中作为催化剂或催化剂载体)的回收利用提供了潜在路径。

Influence of rapid quenching on cyclic stability of La-Mg-Ni system (AB_3-type) electrode alloys

Aiming at the improvement of the cyclic stability of La-Mg-Ni system （PuNi3-type） hydrogen storage alloy, Ni in the alloy was partly substituted by Fe. The electrode alloys of La0.7Mg0.3Co0.45Ni255-xFex （x=0, 0.1, 0.2, 0.3, 0.4） were prepared by casting and rapid quenching. The influence of the quenching on cyclic stability as well as structure of the alloys was investigated in detail. The results of electrochemical measurement indicated that rapid quenching significantly improved cyclic stability. When the quenching rate rose from 0 （As-cast was defined as a quenching rate of 0 m/s） to 30 m/s, the cyclic life of Fe-free alloy （x=-0） increased from 81 to 105 cycles, and for alloy containing Fe（x=0.4）, it grew from 106 to 166 cycles at a current density of 600 mA/g. The results obtained by XRD, TEM and SEM revealed that the as-cast and quenched alloys had multiphase structures, including two major phases （La, Mg）Ni3 and LaNi5 as well as an imptLrity phase LaNi2. Rapid quenching helped the formation of an amorphous-like structure in Fe containing alloys.

Electrocatalytic Activity of Ni/C Electrodes Prepared by Metal Vapor Synthesis For Hydrogen Evolution in Alkaline Solution

The metal vapor synthesis (MVS) methed was used to prepare activatedcarbon supported nickel electrode. The electrocatalytic activity of the electrode forhydrogen evolution reaction(HGR) in alkaline solution was studied. Cathodicpolarization curves showed the electrocatalytic activity of Ni/C electrode prepared byMVS method was higher than that of the one prepared by conventional method.

Effects of rapid quenching on structure and electrochemical characteristics of La_(0.5)Ce_(0.2)Mg_(0.3)Co_(0.4)Ni_(2.6-x)Mn_x(x=0-0.4) electrode alloys

The La-Mg-Ni system PuNi3-type La0.5Ce0.2Mg0.3Co0.4Ni2.6-xMnx(x=0,0.1,0.2,0.3,0.4) hydrogen storage alloys were prepared by casting and rapid quenching. The effects of the rapid quenching on the structure and electrochemical characteristics of the alloys were studied. The results obtained by XRD,SEM and TEM indicate that the as-cast and quenched alloys mainly consist of two major phases,(La,Mg)Ni3 and LaNi5,as well as a residual phase LaNi. The rapid quenching does not exert an obvious influence on the phase composition of the alloys,but it leads to an increase of the LaNi5 phase and a decrease of the(La,Mg)Ni3 phase. The as-quenched alloys have a nano-crystalline structure,and the grain sizes of the alloys are in the range of 20-30 nm. The results by the electrochemical measurements indicate that both the discharge capacity and the high rate discharge(HRD) ability of the alloy first increase and then decrease with the variety of quenching rate and obtain the maximum values at the special quenching rate which is changeable with the variety of Mn content. The rapid quenching significantly improves the cycle stabilities of the alloys,but it slightly impairs the activation capabilities of the alloys.

Degradation analysis of nickel/metal hydride battery and its electrodes materials

The results indicate that during charge and discharge, the expansion of Ni（OH）2 crystal, pulverization of MH alloy particles and falling off from current collector are identified as the main causes for deterioration of Ni/MH batteries. Meanwhile, the contact resistance of inner battery increases due to the deterioration of the negative and positive electrode, and these changes lead to increasing battery body temperature and damaging its electrode and separator. The fibre’s expansion and hole’s diminishment of battery’s separator after degradation will affect the electrochemical performance and cycle life of Ni/MH batteries.

Ti/SnO_(2)-Sb-Ni电极电化学氧化去除水中BIT

1,2-苯并异噻唑啉-3-酮(BIT)是一种新型广谱工业杀菌剂,因其强杀菌能力而难以直接通过传统生化法处理,电化学氧化是一种有效的预处理方法。通过实验对比不同典型阳极对BIT去除率的影响;以锑镍共掺杂钛基二氧化锡电极(Ti/SnO_(2)-Sb-Ni)为阳极电化学氧化BIT,考察BIT电化学氧化过程中不同初始BIT浓度、初始pH、电流密度和硫酸钠浓度等操作参数对BIT去除率的影响,结合紫外-可见吸收光谱和荧光光谱分析,探究BIT降解过程中的结构变化。结果表明:相较于商业电极,Ti/SnO_(2)-Sb-Ni电极可高效电化学氧化BIT及其产物,消除其生物毒性;Ti/SnO_(2)-Sb-Ni电极电化学氧化BIT过程中,最佳电流密度为15 mA/cm^(2),pH和初始硫酸钠浓度对BIT降解影响较小,最佳BIT初始浓度15 mg/L,BIT降解过程中杂环先被破坏,苯环再被破坏。

Effect of surface modification of metal hydride electrode on performance of MH/Ni batteries

A novel method was applied to the surface modification of the metal hydride(MH)electrode of MH/Ni batteries.Both sides of the electrode were plated with a thin silver film about 0.1μm thick using vacuum evaporation plating technology,and the effect of the electrode on the performance of MH/Ni batteries was examined.It is found that the surface modification can enhance the electrode conductivity and decrease the battery ohimic resistance.After surface modification,the discharge capacity at 5C(7.5A)is increased by 212 mA.h and the discharge voltage is increased by 0.11 V,the resistance of the batteries is also decreased by 32%.The batteries with modified electrode exhibit satisfactory durability.The remaining capacity of the modified batteries is 89%of the initial capacity even after 500 cycles.The inner pressure of the batteries during overcharging is lowered and the charging efficiency of the batteries is improved.

Effects of substituting Ni with M (M=Cu, Al and Mn) on microstructures and electrochemical characteristics of La-Mg-Ni system (PuNi_3-type) electrode alloys

In order to improve the electrochemical cycle stability of La-Mg-Ni system (PuNi3-type) hydrogen storage alloy, Ni in the alloys was partially substituted by M (M=Cu, Al, Mn). A new La-Mg-Ni system electrode alloys La0.7Mg0.3Ni2.55-xCo0.45Mx (M=Cu, Al, Mn; x=0, 0.1) were prepared by casting and rapid quenching. The effects of element substitution and rapid quenching on the microstructures and electrochemical performances of the alloys were investigated. The results by XRD, SEM and TEM show that the alloys have a multiphase structure, including the (La, Mg)Ni3 phase, the LaNi5 phase and the LaNi2 phase. The rapid quenching and element substitution have an imperceptible influence on the phase compositions of the alloys, but both change the phase abundance of the alloys. The rapid quenching significantly improves the composition homogeneity of the alloys and markedly decreases the grain size of the alloys. The Cu substitution promotes the formation of an amorphous phase in the as-quenched alloy, and a reversal result by the Al substitution. The electrochemical measurement indicates that the element substitution decreases the discharge capacity of the alloys, whereas it obviously improves the cycle stability of the alloys. The positive influence of element substitution on the cycle life of the alloys is in sequence Al>Cu>Mn, and negative influence on the discharge capacity is in sequence Al>Mn>Cu. The rapid quenching significantly enhances the cycle stability of the alloys, but it leads to a different extent decrease of the discharge capacity of the alloys.