【作者】 周合兵；

【导师】 李伟善； 邱仕洲；

【作者基本信息】 华南师范大学 ， 物理化学， 2004， 硕士

【摘要】 本文采用多种电化学方法和非电化学方法，包括线性电位扫描、循环伏安、电位衰减、计时电量、计时电位、电化学交流阻抗谱、析氢实验、XRD、SEM、ICP等，研究了（1）几种缓蚀剂对锌腐蚀的缓蚀效果；（2）铟和锌在3mol／L KOH溶液中的电化学行为；（3）化学镀铟和锌铟合金对锌在3mol／L KOH溶液中的电化学行为的影响．得到如下结果： 1．使用有些无机和有机缓蚀剂组合能起到协同作用。 2．In₂O₃粉末在3mol／L KOH中的阴极行为分两步还原为单质In。动力学上In₂O₃能与Zn发生反应，铟在锌表面沉积。 3．铟在3mol／L KOH溶液中的阴极行为（即析氢反应）受电化学反应步骤控制；阳极氧化机理遵从溶解—沉积机理，涉及如下反应： In（?）In⁺+e^- （1） In⁺+xOH^-→[In（OH）_x]^1-x（x≥3） （2） [In（OH）_x]^1-x+（3+y-x）OH^-（?）[In（OH）_3+y]^y-（y≥1）+2e^- （3） 较低电位下，反应（1）、（2）较快，反应（3）较慢，表现为一电子反应，较高电位下，反应（1）、（2）和（3）都较快，表现为三电子反应。活化区内的反应主要受扩散步骤控制。当电极表面[In（OH）_3+y]^y-浓度足够高时，便有[In（OH）₃]_ad沉积： [In（OH）_3+y]^y-（?）[In（OH）₃]_ad+yOH^- （4） 阳极极化曲线表现为第一个氧化峰，电位较正时出现第二个氧化峰，是In（OH）₃沉积层下基体铟氧化的结果，氧化产物是非计量的In₂O₃，其稳定性与阳极电位有关。 4．锌在3mol／L KOH溶液中的阴极行为（即析氢反应）也是受电化学反应步骤控制。锌在碱液中于开路电位下即被腐蚀，活化区内发生如下反应： Zn+4OH^-（?）Zn（OH）₄^2-+2e^- （5） Zn+4OH^-（?）ZnO₂^2-+2H₂O+2e^- （6） 当ZnO₂^2-或Zn（OH）₄^2-的浓度足够高时，便有Zn（OH）₂沉积，出现第一个阳极峰。随后，Zn（OH）₂沉积层下的基体Zn氧化形成锌的氧化物，出现第二个阳极峰： Zn+2OH^-（?）ZnO+H₂O+2e^- （7） 锌氧化物形成后电极进入钝化区。ZnO和Zn（OH）₂都能在碱液中溶解： ZnO+H₂O（?）Zn（OH）₂ （8） Zn（OH）:+ZoH一二=户zn（oH）42一（9） 5.镀锢锌电极和锢锌合金电极在3m。呱KOH溶液中的阴极行为（即析氢反应）也是受电化学反应步骤控制. 表面沉积锢能有效提高锌表面的析氢过电位，增大析氢电阻，抑制锌腐蚀共扼反应中的阴极支，因此表面沉积锢能有效抑制锌在开路时的自放电，表现为开路时的腐蚀反应电阻增大.厚度适量的镀锢层能提高锌在放电初期的活性，锌的阳极溶解是通过形成锌一锢溶液来完成的.此外厚度适量的镀锢层还能提高锌的可充性能，这在二次锌电池中的应用很有意义. 在锌粉中添加锢也能有效抑制锌表面的析氢反应，这种抑制作用随电极中锢含量的增多而加强.锌在锌锢合金中的阳极溶出机理与金属单质锌相同，但不同于表面覆盖锢层的金属锌.更多还原

【Abstract】 The effects of indium on the electrochemical performances of zinc in KOH solution are investigated by electrochemical and nonelectrochemical methods, including linear potential sweep, cyclic voltammogram, chronocoulometry, chronopotiometry, AC impedance, hydrogen evolution measurement, XRD, SEM and ICP. The investigation involves: (1) the inhibition of zinc corrosion by organic and inorganic inhibitors, (2) the electrochemical performances of indium and zinc in 3mol/L KOH solution, (3) the influences of electroless-plated indium on zinc and in zinc-indium alloys on the electrochemical performances of zinc in 3mol/L KOH. Following results are obtained:1. There is a significant synergism for zinc corrosion when some kinds of organic and inorganic inhibitors are used together. The reaction between Zinc and In2O3 can take place kinetically, resulting in the deposition of indium on zinc..2. Hydrogen evolution process on indium in 3mol/L KOH solution is controlled by electrochemical reaction step. Anodic oxidation of indium takes place in a dissolution-precipitation model. The anodic oxidation of indium proceeds by two steps at active region, forming [In(OH)x]1-x (x≥3) from Indium and [m(OH)3+y]y’from [In(OH)x]1-xIn = In+ + e- (1)In+ + xOH- --> [In(OH)x]1-x (x≥3) (2)[In(OH)x]1-x+ (3+y-x)OH- = [In(OH)3+y]y-(y≥1) + 2e- (3)At lower potential, the formation of [In(OH)x]1-x is fast but the formation of [In(OH)3+y]y-is slow, so the reaction behaves as one electron transfer. At higher potential, both formations of [In(OH)x]1-x and [In(OH)3+y]y- are fast, so the reaction behaves as three electrons transfer. [In(OH)3]ad deposits when the concentration of [In(OH)3+y]y- near the electrode surface is satuated. The reactions at active region are controlled by mass transport step. [In(OH)3]ad is not stable and can dissolve into the solution:[In(OH)3]ad + yOH- = [In(OH)3+y]y-(4)At higher potential, indium is oxidized directly to compact indium oxide under thedeposited [In(OH)3]ad film. The stability of the indium oxide depends on the formation potential.3. Hydrogen evolution process on zinc in 3mol/L KOH solution is also controlled by electrochemical reaction step. Zinc corrosion takes place at open circuit potential in 3mol/L KOH solution. The anodic oxidation of zinc also follows a dissolution-precipitation model. Zinc is oxidized to ZnO22~ or Zn(OH)42- at active region:Zn + 4OH-=Zn(OH)42- + 2e- (5)Zn + 4OH-=ZnO22- + 2H2O + 2e (6)When the concentration of these anions reaches to saturation, Zn(OH)2 is deposited on the surface of zinc resulting in the first anodic oxidation peak.Then the second anodic peak appears due to the formation of compact zinc oxide under the deposited Zn(OH)2- Both Zn(OH)2 and ZnO are unstable in 3mol/L KOH solution and can dissolve into solution.ZnO + H2O = Zn(OH)2 (7)Zn(OH)2 + 2 OH* = Zn(OH)42- (8)4. Hydrogen evolution process on zinc with electroless-deposited indium and Zn-In alloys in 3mol/L KOH solution is controlled by electrochemical reaction step. Both electroless-deposited indium and indium inside Zn-In alloys can increase hydrogen evolution overpotential and reaction resistance on zinc electrode in 3mol/L KOH solution, which inhibits zinc corrosion. The inhibition increase with the increase of indium layer thickness and indium content in Zn-In alloys.Electroless-deposited indium with suitable thickness can improve the activity of zinc. Electroless-deposited indium can also improve the rechargeability of zinc, which is valuable to the application of zinc in secondary batteries.The anodic dissolution of zinc with deposited indium is different to that of zinc in Zn-In alloys. The former takes place in solid indium solution. The latter in alloys, which is the same as pure metal Zinc.更多还原