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Thesis Advisor舒代萱
Degree Grantor中国科学院研究生院
Abstract本文在本实验室Ti/SnO_2-Sb_2O_3/MnO_2电极制备研究的基础上,采用稳态技术和暂态技术、包括恒电位电流时间曲线,恒电流电位时间曲线,大幅度线性扫描循环伏安曲线和单扫描伏安曲线,研究了氧化锰电极在酸性溶液中的阳极特性和氧气在氧化锰电极上的放氧过程,推出了假设的阳极放氧机理。结果表明:(1)在放氧反应中,H_2O被认为是电荷交换的粒子;在发生放氧前,水首先在电极表面吸附。(2)在氧化锰电极中,存在低价的锰氧化物,且起着活性格点的作用。(3)伴随放氧过程,存在锰的价态变化,对于放氧过程起着催化作用。(4)认为反应M(III)OH~- → M(IV)OH~- +e为电化学反应的控制步骤。(5)在同一极化电位下,随pH增加,极化电流增加,但i与[H~+]不具有负一次方关系。电位不同,pH对级化电流的影响不同。本文还采用俄歇电子能谱分析及其它电化学实验,对电极的失活过程进行了研究,结果表明:(1)钛基氧化锰电极涂层内部,近失活电极与新电极比较,并无明显的氧和硫存在,说明不是氧和电解液的渗透扩散导致电极失活。(2)电极失活的主要原因是电极表面活性点的溶解和溶解的锰在电极上的重镀并覆盖表面。
Other AbstractThe anodic characteristics of Mn oxides of Ti/SnO_2-Sb_2O_3/MnO_2 electrode and anodic evolutions of oxygen in acidic solutions were investigated by means of steady-state polarization curve and transient techniques including potentiostatic step method, galvanostatic step method, cyclic voltammetry and single sweep voltammetry. The mechanism of oxygen evolutions in acidic solutions on Mn oxides was developed these following results were obtained: (1) The H_2O moleculars that play a role of charge transference in anodic evolutions of oxygen in acidic solutions are firstly adsorbed on the surface of electrode before oxygen evolutions. (2) Some Mn oxides of low valent are existed in the surface. It is the Mn(III) sites on the oxide surface that is considered as the active sites for the oxygen evolution reactions. (3) During the process of oxygen evolutions, the valent change of Mn oxide is taken place, which catalyzes oxygen evolution. (4) The reaction M(III)OH~-, M(IV)OH~+ e is considered as the rate-determing step in the electro-chemical reactions. (5) At the same polarization potential, the polarization current increases with pH values. The current is not inversely proportional to [II~+]. The affected degree of pH to current will be different with the potential. The anodic active losing was investigated by Auger-electron Energy Specyra and other electro-chemical methods. It was suggested: (1) In the coating of anode, there are no obviously increasing oxygen and sulphur for electrolysied anodes compared with the new ones. It is concluded that it is not the permeating of electrolyte and diffusing of oxygen that leed to the active losing. (2) The main reasons of active losing of anodes are the dissolution of active sites on the surface of electrodes and surface covering by re-plating of dissolated Mn.
Document Type学位论文
Recommended Citation
GB/T 7714
崔军. 钛基氧化锰阳极的基础研究[D]. 中国科学院研究生院,1988.
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