氟化物电沉积铬中十八烷基三甲基氯化铵的阻氢作用

在硫酸铝、草酸钠、硫酸钠、氟化钠及硼酸的混合介质中,用极化曲线法研究了十八烷基三甲基氯化铵(简称1831)在铬电极表面的阻氢作用.采用正交试验,讨论了1831用量、温度、pH和搅拌速率对析氢电位负移量的影响,确定了最佳实验条件为:1831 20mg/L,温度35℃,pH 1.7,搅拌速率0.56mL/s.在该工艺条件下,金属铬沉积的电流效率提高了13.24%.实验证明,1831是氟化物体系中铬电沉积的有效阻氢剂.     

Ni-Mo合金电极的制备条件对其析氢性能的影响

采用电沉积技术制备了N i-M o合金电极,研究了电流密度、pH、温度对电极析氢催化活性的影响,得出了较适宜的工艺配方,该配方下制备的合金结构介于晶态和非晶态之间,具有较好的析氢催化活性。在28%的KOH溶液中,析氢电流密度为100 mA/cm2时,析氢电位比N i电极降低近300 mV。     

节能析氢电极的研究

用电镀法制备了镍－钼析氢电极，考察了制备条件对该电极析氢活性的影响。本文实验条件下，镀液中钼与镍的原子比为1：2，电镀电流密度为18mA·cm－2时，制备的镍－钼电极有较高的折氢活性。与现行氯碱电解槽的低碳钢网析氢电极比较，析氢过电位降低0．116V。     

氯酸盐电解的铁黑阴极

<正>1 弓言 节电是电解工业的重要研究课题.自采用钛钉金属阳极后,阴极就成为节电研究的主攻方向.气体扩散阴极和非铁活性阴极的研究较常见,前者用氧还原反应替代析氢电极反应’‘’,后者是在基体表面电沉积低氢过电位的Ni合金”-”.本文给出的铁黑阴极是一种新型电极,为电解工业阴极研究开辟了新途径. 在mH—5～6的亚铁盐溶液中,采用电化学手段建立很薄的表面富氧碱区（厚度约20urn）,将原铁阴极表面加工成均匀细颗粒状的黑色表面,称铁黑阴极.该方法简便,材料低廉,可循环再生.本文用电镜图和电子能谱图确定铁黑阴极表面结构和组分.在氯酸盐电解条件下进行析氢极化曲线和90天寿命试验.2 实验 铁黑阴极与原铁阴极的面积相同,约0.scm’.原铁阴极采用氯酸盐电解工业使用的低碳钢材料（福州第一化工厂提供）. 铁黑阴极表面的电镜图（SEM）和X光电子能谱图（XPS）分别在日本S-520扫描电镜仪和英国＊既＊-＊K工电子能谱仪上测试.＊陀图上结合能数值已用C;s内标校正. 测量极化曲线电解液组成为NaCI 1609/din‘和Na。Cr。O,3g/din’,PH—6,温度65士ZC.辅助电极和参比电极分别为钛钉阳极和饱和甘汞电极.阴极电流密度范围为0.1～3.okA/m’. 寿命试验的初始电解液组成与测极化曲线时相同,电液量100cm‘.将原铁阴极     

电解水Ni-S电极合金的研究

采用电沉积法在镍网上制备Ni-S合金,在固定的溶液组成、电镀的电流密度和温度的条件下,研究电沉积时间对电极析氢过电位的影响。试验结果表明,与未镀合金的电极相比,Ni-S合金电极的析氢过电位可降低130mV,具有很好的析氢反应活性。     

贮氢合金电极在山梨醇制备中的应用

用贮氢合金作催化还原电极恒电位电解葡萄糖 ,得出合金的表面处理及电极的活化可提高山梨醇电流效率至 80 %以上的结论。同时贮氢电极与Pb电极及发泡Ni电极作了对比 ,发现电解葡萄糖制备山梨醇过程中 ,贮氢电极是较好的还原电极。用贮氢电极 (2 )做阴极 ,30℃ ,电流密度为 80 0mA/dm2 ,葡萄糖溶液及硫酸钠支持电解质浓度均为 0 .5mol/L ,pH =8的条件下 ,电解葡萄糖制山梨醇电流效率高达 94% ,葡萄糖转化率达 80 %以上。     

Ni-W-P/ZrO2复合电极的制备及其催化析氢性能

在电沉积Ni-W-P合金的工艺基础上,通过加入ZrO2微粒,制备了Ni-W-P/ZrO2复合电极.通过扫描电子显微镜(SEM)对电极的表面形貌进行了表征,利用稳态极化曲线、电流密度-时间(i-t)曲线等电化学测试方法研究了电极的催化析氢性能,考察了镀层中ZrO2复合量对电极析氢性能的影响.     

纳米Pd修饰WO3电极及其催化析氢性能

将非晶结构Fe-W合金浸泡在0.5 mol/LH2SO4溶液中,在电极表面形成WO3层,厚度约720nm。通过化学法在半导体WO3上沉积金属Pd,扫描电镜和扫描隧道显微镜测试结果表明,沉积5m in后Pd的平均颗粒尺寸约为10 nm。在0.5 mol/LH2SO4溶液中的极化曲线测试结果表明,纳米Pd修饰WO3电极具有优异的电催化及光催化析氢活性,在500W碘钨灯照射下,电流密度为6 A/dm2时电极的析氢过电位减小30 mV以上。     

双脉冲电沉积制备Ni-聚苯胺复合电极及其析氢性能的研究

采用控制双脉冲电位沉积技术制备N i-聚苯胺复合电极。扫描电镜下观察电极表面呈菜花状结构,比表面积约为普通镀N i电极的4~50倍。N i-PAN复合电极的X射线衍射谱图中分别出现了N i和PAN的特征峰。通过测试复合电极在模拟氯碱工业电解液中的阴极极化曲线,研究了N i-PAN电极的析氢性能,结果显示当电流密度为0.10 A/cm2时,析氢过电位较镀N i电极降低约350 mV。复合电极性能稳定,可作为氯碱工业用活性阴极,能显著降低能耗。     

电沉积方法制备镍硫析氢电极及其电化学性能

采用恒电流电沉积方法制备Ni-S电极,通过极化曲线研究了硫脲质量浓度、电流密度、镀液温度、电沉积时间等对Ni-S电极析氢性能的影响,获得了较佳的制备工艺:NiSO4·6H2O187.2g/L,硫脲100g/L,H3BO340g/L,NaCl 20g/L,pH=4,电流密度30 mA/cm2,镀液温度55℃和电沉积时间1...     

碱性溶液中硼氢化钠在铜阳极上的氧化行为

Polarization data of BH^-₄ oxidation on Cu anode in alkaline solution were measured at steady state by a self-made experimental cell. The experimental polarization curve showed three regions：the region at lower over-potential η（below 0.4 V approximately）,the region at higher η（above 0.6 V approximately）and the transitional region at medium η. It was found that the limiting current density is caused by the limiting elemental step rather than the external mass transport. The apparent reaction order with respect to BH^-₄ changes from 0 to 1. The active energy is about 40 kJ·mol^-1 in both regions with lower and higher η,and is higher than 40 kJ·mol^-1 in the transitional region. With the experimental temperatures and NaOH concentration,the hydrogen production rates released by the electrode reaction were measured at ［BH^-₄］/［OH^-］ratios of 1∶40,1∶20,1∶6. 7 and 1∶4,which is strongly dependent on the over-potential. The apparent number of released electron n by the reaction was calculated by using the measured amounts of hydrogen and coulomb. Higher value of n was obtained at lower ［BH^-₄］/［OH^-］ratio,higher temperature as well as higher over-potential. Under the experimental conditions,the value of n varies from 0 to 7,while in the transitional region it is just in the range of 3 to 5. The experimental results indicate that the limiting current density or n value will increase by virtue of proper experimental conditions. However,to considerably increase the current density at lower over-potential requires a modified anode with higher activity.     

碳毡基体上电沉积Ni-Mo合金及其催化析氢性能

以碳毡为基体,采用瓦特型镀镍工艺电沉积镍,获得碳镍（C-Ni）电极,然后在离子液体体系中以C-Ni为基体电沉积Ni-Mo合金。采用扫描电镜和X射线衍射仪对合金电极的表面形貌和结构进行了表征,通过阴极极化曲线、交流阻抗等电化学测试研究了其析氢催化性能。实验结果表明,制得的Ni-Mo合金中Mo的质量百分含量约为5.12%,平均晶粒尺寸约为2.2 nm,为纳米晶结构;极化曲线测试表明,当电流密度为0.1 A·cm^-2时,Ni-Mo/C-Ni合金电极催化析氢电位较C-Ni电极正移108 mV,较碳毡正移557 mV,较水溶液中沉积的紫铜基Ni-Mo合金电极正移约50 mV;连续电解和断电流实验结果表明Ni-Mo/C-Ni合金电极具有良好的电化学稳定性,实用前景广阔。     

Effects of boric acid on hydrogen evolution and internal stress in films deposited from a nickel sulfamate bath

The effects of boric acid additions on the pH close to the electrode surface, on the hydrogen evolution reaction and on the internal stress in the plated films were studied for the high speed electroplating of nickel from a nickel sulfamate bath at a current density close to the nickel ion limiting current density. The study was carried out at 50 °C and pH 4.0 using a 1.55 M nickel sulfamate plating bath containing boric acid at concentrations ranging from 0 to 0.81 mol L^–1. The variation of the internal strain in the plated nickel films was determined in situ using a resistance wire-type strain gauge fitted to the reverse side of the copper electrode substrate. The solution pH at a distance of 0.1 mm from the depositing nickel film was measured in situ using a miniature pH sensor assembly consisting of a thin wire-type antimony electrode and a Ag/AgCl/sat. KCl electrode housed in a thin Luggin capillary. The addition of boric acid was shown to effectively suppress the hydrogen evolution reaction at nickel electrodeposition rates (18.0 A dm^–2) close to the limiting current density (~20 A dm^–2). Consequently, the solution pH adjacent to the plating metal surface was maintained at a value close to that in the bulk solution and the development of high internal stresses in the deposited nickel films was avoided.     

钴钨复合电极在碱性介质中的电催化析氢性能

为提高电极的电催化析氢性能,在钴电沉积中加入钨粉,制得钴钨复合电极,采用阴极极化曲线法、交流阻抗技术和扫描电子显微技术研究了电极在碱性介质中的催化析氢性能。与钴电极相比,钴钨复合电极表面粗糙,具有较大的交换电流密度和较小的析氢反应电阻。结果表明：复合电极的电催化析氢性能优于钴电极。     

高活性镍钴铁三元合金电极的制备及析氢性能研究

为进一步提高镍基电极的析氢性能,采用恒电位沉积法,通过改变镀液中各合金的质量浓度比、沉积电位、沉积时间等条件,制备出一种高活性的镍钴铁三元合金电极。通过测定电极在1 mol/L的NaOH溶液中的极化曲线,得到最佳的沉积工艺条件为:36.25 g/L NiSO_4·6H_2O,1.25 g/L NiCl_2·6H_2O,5 g/L CoSO_4·7H_2O,7.5 g/L FeSO_4·7H_2O,10 g/L H_3BO_3,0.5 g/L抗坏血酸,1 g/L十二烷基硫酸钠,pH=4.0,电沉积电位-1.45 V,电沉积时间300 s。阴极极化曲线测试结果表明在5 A/dm^2的条件下,镍钴铁三元合金电极的析氢过电位降低至121 mV,相比于纯镍电极过电位降低近50%,相比于镍钴电极过电位降低近35%。     

Electrochemistry of active chromium: Part II. Three hydrogen evolution reactions on chromium in sulfuric acid

It was shown that chromium in deaerated sulfuric acid exhibits two stable corrosion potentials, depending whether the metal had previously been in contact with air or subjected to activation by cathodically evolving hydrogen. Electrochemical polarization measurements, as well as measurements of the actual metal dissolution rate at the corrosion potentials, anodic or cathodic polarization, using the analytical determination of Cr ions in the solution, weight-loss of metal, or volumes of hydrogen evolved, showed that hydrogen can evolve on chromium by three different reaction mechanisms. The first one is the electrochemical hydrogen evolution reaction from H⁺ ions at the bare chromium surface obtained by cathodic activation. This reaction and the active anodic dissolution of chromium determine one stable corrosion potential. The second reaction is the reaction of H⁺ ions on the oxidized chromium surface which, coupled with the anodic dissolution of passivated chromium determines the other stable corrosion potential. The third one is the “anomalous” or chemical reaction of chromium with water molecules and hydrogen ions whereby hydrogen is liberated. This is a potential independent reaction, occurring on the bare metal surface, and which is at pH <2 several times faster at the corrosion potential than the electrochemical hydrogen evolution reaction. The consequence is that the overall corrosion rate is several times faster than that determined by the usual electrochemical methods. The applicability of the different methods of measuring electrochemical corrosion rates and cathodic current efficiencies in chromium plating is discussed. Also, a possible role of the “anomalous” chromium dissolution in corrosion fatigue and stress corrosion cracking of stainless steels is considered.     

控制电位脉冲电沉积法制备析氢Ni-S电极

采用控制电位脉冲电沉积法制备Ni-S合金电极,并在25%NaOH溶液中测试阴极极化曲线和交流阻抗,表征所制备电极的催化析氢活性。探讨了脉冲电流密度,脉冲限制电位及硫脲加入量对电沉积的影响,确定了电沉积制备Ni-S电极的适宜条件。结果显示:脉冲电流密度为7.1 A/dm2,脉冲电位上限为-0.70 V,脉冲电位下限为-1.75 V,V(瓦特镍溶液)(290 g/L NiSO4.6H2O,50 g/LNiCl2.6H2 O,40 g/L H3 BO3)与V(10%硫脲)比值为20∶8,制备的Ni-S电极具有最高的催化析氢性能。     

Electrodeposition of Ni, Co and Ni-Co alloy powders

In this paper the polarization characteristics of the processes of Ni and Co powders and Ni-Co alloy powders electrodeposition from ammonium sulfate containing supporting electrolyte are investigated as a function of Ni²⁺ and Co²⁺ ions concentrations. It is shown that the correct polarization curves for Ni and Co powders and Ni-Co alloy powders electrodeposition could be obtained only after IR drop correction, since the total current density of electrodeposition at the most negative potential of −1.4 V versus Ag|AgCl is extremely high (up to about 3-6 A cm⁻²) as a consequence of simultaneous hydrogen evolution which starts immediately after the beginning of metals (alloys) deposition. After determining the current density for hydrogen evolution and its subtraction from the total current density, correct polarization curves for Ni and Co powders and Ni-Co alloy powders electrodeposition are obtained. They are found to be different for each ratio of Ni²⁺/Co²⁺ ions concentration. It is also concluded that the shape of the polarization curves in all cases is practically defined by the shape of the polarization curve for hydrogen evolution. The morphology and composition of electrodeposited powders were also found to be sensitive to the ratio of Ni²⁺/Co²⁺ ions concentration.