化学镀Ni—Co—P合金对Mm（NiCoAiMn）5贮氢合金电极动力学性能的影响

通过电化学方法,研究了化学镀Ni-Co-P合金对Mm(NiCoAlMn)5五元稀土贮氢合金电极动力学性能的影响,研究表明,引入很少量（1－2％）Co的Ni-Co-P合金镀层可有效地提高MH电极的交换电流密度io,极限电流密度iL及α相中氢的扩散系数Dα（H）,还研究了化学镀Ni-Co-P合金对稀土贮氢合金电极循环伏安（CV）曲线和阴,阳极极化曲线及对称因子β的影响,进而阐明了化学镀对MH电极过程动力学的影响。     

微包覆钴贮氢合金电极电化学性能的研究

以化学镀钴方法微包覆处理贮氢合金,用交流阻抗、循环伏安以及模拟电池充放电实验研究了该贮氢合金电极的电化学性能.结果表明,贮氢合金经包覆钴后,即可减小电极表面的电化学反应阻抗,提高其催化活性,并降低充放电过程的极化,从而增大了电极的放电容量和充电效率.相关的电极过程为扩散控制.     

测试技术在稀土贮氢合金研究中的应用

本文较为详细地介绍了研究稀土贮氢合金性能过程中几种常用的测试技术.在贮氢合金组织结构方面,应用XRD、SEM和金相测试技术,研究贮氢合金的相结构,通过有关公式计算合金晶粒尺寸,以及反映热处理工艺前后相结构、晶粒形貌、晶界的变化情况.在贮氢合金吸放氢机理方面,通过将贮氢合金粉制作成微电极,采用恒电位阶跃、交流阻抗、循环伏安电化学测试技术,研究稀土贮氢合金电极反应的动力学性能,计算合金电极的交换电流密度、氢扩散系数及固/液界面电荷传递电阻等参数;采用PCT测试仪,研究贮氢合金的储氢量、平衡氢压等性能.在贮氢合金电化学性能方面,通过采用模拟电池测试技术,研究贮氢合金的活化、放电容量、放电平台、循环等性能.     

测试技术在稀土贮氢合金研究中的应用

本文较为详细地介绍了研究稀土贮氢合金性能过程中几种常用的测试技术。在贮氢合金组织结构方面，应用XRD、SEM和金相测试技术，研究贮氢合金的相结构，通过有关公式计算合金晶粒尺寸，以及反映热处理工艺前后相结构、晶粒形貌、晶界的变化情况。在贮氢合金吸放氢机理方面，通过将贮氢合金粉制作成微电极，采用恒电位阶跃、交流阻抗、循环伏安电化学测试技术，研究稀土贮氢合金电极反应的动力学性能，计算合金电极的交换电流密度、氢扩散系数及固／液界面电荷传递电阻等参数；采用PCT测试仪，研究贮氢合金的储氢量、平衡氢压等性能。在贮氢合金电化学性能方面，通过采用模拟电池测试技术，研究贮氢合金的活化、放电容量、放电平台、循环等性能。     

微电极定量方法评价贮氢合金的电化学性质

本文介绍了评价贮氢合金电化学性能的粉末微电极定量方法，贮氢合金粉末微电极的电极厚度和半径仅几十微米，材料用量约几微克，从而降低了欧姆极化和液相浓度极化，排除了粘结剂等电极工艺对性能的影响。     

贮氢电极的电化学研究（Ⅱ）—贮氢电极的交流阻抗研究

用交流阻抗的方法对贮氢电极进行了研究。实验表明，贮氢电极的交流阻抗图由两个半圆组成，高频区半圆对应于电化学反应，低频区半圆对应于氢原子在贮氢合金表面的吸附过程。低频区的半圆受电极活化次数和放电深度的影响。活化次数越多、放电时间越长、低频区半圆越小。提出了贮氢电极的等效电路图，对这些实验结果作出了解释。     

富镧和富铈混合稀土贮氢电极的性能

富镧和富铈混合稀土贮氢电极的性能＊赵东江马松艳（黑龙江省绥化师专化学系绥化市１５２０６１）关键词混合稀土贮氢电极性能中图分类号Ｏ６４６．５４混合稀土贮氢合金具有良好的电化学特性和较低的价格，成为贮氢电极研究的主要对象，已经开发出许多实用的电极材料［１...     

电解液添加成份对贮氢电极性能影响的初步研究

电解液添加成份对贮氢电极性能影响的初步研究蔡称心，黄翠虹（南京大学化学系，南京，２１０００８）王宝忱（中国科学院长春应用化学研究所，长春１３００２２）关键词：贮氢电极，ＭＨ／Ｎｉ电池，添加剂自从Ｊｕｓｔｉ和Ｅｗｅ￣［１，２］发现贮氢合金能够用电化学方...     

温度对贮氢合金MlNi3.75Co0.65Mn0.4Al0.2动力学性能的影响

在-20℃～85℃的范围内系统地研究了温度对贮氢合金MINi3.75Co0.65Mn0.4Al0.2动力学性能的影响.结果表明:该贮氢合金电极的电化学反应电阻Rt,欧姆内阻Ro,阴极极化过电位,阳极极化过电位,阳极极化过程中的电化学反应过电位ηa和浓差极化过电位ηa均随温度的升高而减小,该电极的交换电流密度i0,对称因子β和电极中氢的扩散系数D随温度的升高而增大.当放电电流密度较低时,电化学反应是整个电极过程的速度控制步骤;当放电电流密度较高时,氢的扩散是整个电极过程的速度控制步骤;在中等放电电流密度下,电极过程由电化学过程和氢的扩散过程混合控制.该电极中电化学反应过程和氢扩散过程的活化能分别为28.1 kJ·mol-1和19.9 kJ·mol-1.     

La0.5Mg0.5(Ni1-xCox)2.28(x=0.0～0.2)储氢合金的相结构和电化学性能

用冷坩埚磁悬浮熔炼方法制备La0.5Mg0.5(Ni1-xCox)2.28(x=0.0～0.2)贮氢电极合金,采用SEM,EDS,XRD,P-C-T测试及三电极电化学性能测试研究合金的相成分、相结构、P-C-T曲线和电化学性能.EDS结合XRD分析表明,La0.5Mg0.5Ni2.28及La0.5Mg0.5(Ni0.85Co0.15)2.28合金主相均为MgSnCu4型的LaMgNi4相,还包括LaNi5和(La,Mg)Ni3相.P-C-T曲线显示,合金均有双放氢平台,合金的贮氢量由Co替代量x=0.0时的1.24%增大至极大值x=0.15时的1.27%.电化学性能测试表明,随Co含量增加,最大放电容量从329.0mAh·g-1(x=0.0)增大到337.5 mAh·g-1(x=0.15),合金活化性能及高倍率放电性能明显改善;循环稳定性无明显变化.     

Investigation of the influence of nickel content on the correlation between the hydrogen equilibrium pressure for hydrogen absorbing alloys and the capacity of MH electrodes in open and closed cells

Two series of overstoichiometric AB_2.4 alloys [(Zr_0.35Ti_0.65)(V_1.33Cr_0.4Fe_0.27)_{2– x} Ni_{0.4+ x} and (Zr_0.5Ti_0.5)(V_0.8Mn_0.8Cr_0.4)_{2– x} Ni_{0.4+ x} ], differing in the Zr to Ti ratios in group A and the presence of Mn or Fe in group B, were examined to consider the influence of various amounts of nickel on the structural parameters following the sorption of hydrogen. To predict the electrochemical behaviour of the prepared alloys as negative electrodes for Ni-MH cells, the pressure-composition isotherms (PCT) determined for the gas/solid phase system were correlated with the electrochemical pressure-composition (EPC) isotherms estimated from the rest potential of the alloy electrode. For preliminary assessment of the practical usefulness of the prepared samples, the electrodes made of all the alloys were subjected to charge/discharge measurements in a half-cell in 6 M KOH solution and the discharge capacities were estimated. Of the alloys with Fe and Mn components, the samples (Zr_0.35Ti_0.65)(V_0.93Cr_0.28Fe_0.19Ni_1.0) and (Zr_0.5Ti_0.5)(V_0.68Mn_0.68Cr_0.34Ni_0.7) provided the highest capacities. These alloys were chosen for testing the charge/discharge cycleability in closed Ni-MH cells. The reversibility of the cell with the former sample decreased significantly around the 25th cycle, whereas the discharge capacity of the cell with the latter sample remained almost unchanged during 100 cycles of testing. Electronic Publication     

Hydride Formation Diminishes CO2 Reduction Rate on Palladium

The catalytic hydrogenation of CO₂ includes the dissociation of hydrogen and further reaction with CO₂ and intermediates. We investigate how the amount of hydrogen in the bulk of the catalyst affects the hydrogenation reaction taking place at the surface. For this, we developed an experimental setup described herein, based on a magnetic suspension balance and an infrared spectrometer, and measured pressure-composition isotherms of the Pd−H system under conditions relevant for CO₂ reduction. The addition of CO₂ has no influence on the measured hydrogen absorption isotherms. The pressure dependence of the CO formation rate changes suddenly upon formation of the β-PdH phase. This effect is attributed to a smaller surface coverage of hydrogen due to repulsive electronic interactions affecting both bulk and surface hydrogen.     

Hydrogen sorption–desorption studies on ZrCo–hydrogen system

The ZrCo–H₂ system was investigated in this study owing to its importance as a suitable candidate material for storage, supply, and recovery of hydrogen isotopes. Desorption hydrogen pressure-composition isotherms were generated at six different temperatures in the range of 524–624 K. A van’t Hoff plot was constructed using the plateau pressure data of each pressure-composition isotherms and the thermodynamic parameters were calculated for the hydrogen desorption reaction of ZrCo hydride. The enthalpy and entropy change for the desorption of hydrogen were found to be 83.7 ± 3.9 kJ mol^?1 H₂ and 122 ± 4 J mol^?1 H₂ K^?1, respectively. Hydrogen absorption kinetics of ZrCo–H₂ system was studied at four different temperatures in the range of 544–603 K and the activation energy for the absorption of hydrogen by ZrCo was found to be 120 ± 5 kJ mol^?1 H₂ by fitting kinetic data into suitable kinetic model equation.     

Ternary MgTiX-alloys: a promising route towards low-temperature, high-capacity, hydrogen-storage materials

In the search for hydrogen-storage materials with a high gravimetric capacity, Mg(y)Ti((1-y)) alloys, which exhibit excellent kinetic properties, form the basis for more advanced compounds. The plateau pressure of the Mg--Ti--H system is very low (approximately 10(-6) bar at room temperature). A way to increase this pressure is by destabilizing the metal hydride. The foremost effect of incorporating an additional element in the binary Mg--Ti system is, therefore, to decrease the stability of the metal hydride. A model to calculate the effect on the thermodynamic stability of alloying metals was developed by Miedema and co-workers. Adopting this model offers the possibility to select promising elements beforehand. Thin films consisting of Mg and Ti with Al or Si were prepared by means of e-beam deposition. The electrochemical galvanostatic intermittent titration technique was used to obtain pressure-composition isotherms for these ternary materials and these isotherms reveal a reversible hydrogen-storage capacity of more than 6 wt. %. In line with the calculations, substitution of Mg and Ti by Al or Si indeed shifts the plateau pressure of a significant part of the isotherms to higher pressures, while remaining at room temperature. It has been proven that, by controlling the chemistry of the metal alloy, the thermodynamic properties of Mg-based hydrides can be regulated over a wide range. Hence, the possibility to increase the partial hydrogen pressure, while maintaining a high gravimetric capacity creates promising opportunities in the field of hydrogen-storage materials, which are essential for the future of the hydrogen economy.     

Reversible hydrogen storage property and structural analysis for face-centered cubic hydride Mg0.82Zr0.18H2 prepared by gigapascal hydrogen pressure method

The face-centered cubic (fcc) type magnesium-zirconium hydride (Mg0.82Zr0.18Hx) was synthesized by means of the ultrahigh pressure (UHP) technique, which could generate 8 GPa of hydrogen pressure. The differential scanning calorimeter (DSC) measurements indicated that the fcc phase exhibited reversible hydrogen releasing and restoring properties under 0.5 MPa of hydrogen pressure. On the pressure-composition isotherms, the released and restored hydrogen capacities were estimated to be 3 approximately 3.5 wt %. The Rietveld analysis for synchrotron X-ray diffraction (XRD) data showed that the fcc phase had around 70 wt % mass fraction and was preserved without decomposition during hydrogen releasing and restoring cycles.     

Catalytic deoxygenation of high-purity water using membrane electrode units

A new method for water deoxygenation using membrane technologies was suggested. The method is based on electrochemical reduction of dissolved oxygen on the surface of membrane electrode units in combination with its chemical reduction with hydrogen on a catalytically active sorbent. A pilot setup for deoxygenation of high-purity water with the output of up to 200 L h^–1 was developed on the basis of the results obtained.     

LaNi5型储氢合金表面修饰及其电化学性能研究

0引言近年来,随着科学技术水平的提高和世界范围环保意识的增强,汽车尾气所造成的环境污染问题日益引起人们的重视[1]。电动汽车的发展可以有效制约燃油汽车所造成的环境污染。MH/Ni电池是一种无污染的“绿色能源”,它具有高比能量、高比功率、长寿命及安全性好等优异性能,非常     

Hydrogen-storage properties of solid-solution alloys of immiscible neighboring elements with Pd

Rh and Ag are the elements neighboring Pd, which is well known as a hydrogen-storage metal. Although Rh and Ag do not possess hydrogen-storage properties, can Ag-Rh alloys actually store hydrogen? Ag-Rh solid-solution alloys have not been explored in the past because they do not mix with each other at the atomic level, even in the liquid phase. We have used the chemical reduction method to obtain such Ag-Rh alloys, and XRD and STEM-EDX give clear evidence that the alloys mixed at the atomic level. From the measurements of hydrogen pressure-composition isotherms and solid-state (2)H NMR, we have revealed that Ag-Rh solid-solution alloys absorb hydrogen, and the total amount of hydrogen absorbed reached a maximum at the ratio of Ag:Rh = 50:50, where the electronic structure is expected to be similar to that of Pd.     

(Ni-Co)-WC复合电极的析氢催化性能

采用 复合电沉 积方法获 得了（ Ｎｉ Ｃｏ） Ｗ Ｃ 复合电极 ,考 察了 复合 电极 在弱 酸性、碱性 和中性介质 中的析 氢电催化 性能,并 在弱酸性 介质中 进行了电 化学稳定 性实验 ． 结果 表明,复 合电极具有优越 的析氢 电催化性 能和良好 的电化 学稳定性 ．     

碳纳米管的电化学贮氢性能研究

研究了碳纳米管电极的电化学性能 ,其电化学储氢量达到 2 0 0mAh·g 1且具有高的电化学活性和良好的循环寿命 .采用循环伏安法研究了氢在碳纳米管电极上吸附 /氧化机理 .