摘要
为了解硝酸介质中H_(2)C_(2)O_(4)在铂、玻碳和金刚石掺硼(BDD)电极上的电解氧化机理,使用循环伏安、线性扫描伏安等方法开展了电化学测试,研究了电极电位、电流密度以及硝酸浓度对H_(2)C_(2)O_(4)氧化的影响,并分析了硝酸的影响主要来自于H+。在铂电极上,推测H_(2)C_(2)O_(4)不仅发生电氧化,而且吸附态的·OH与吸附态H_(2)C_(2)O_(4)反应生成CO_(2)和H_(2)O。在金刚石掺硼电极上,·OH的间接氧化是H_(2)C_(2)O_(4)氧化的主要作用,硝酸浓度增加使·OH产生量变少,进而导致H_(2)C_(2)O_(4)氧化速率降低。使用旋转圆盘玻碳电极测定了H_(2)C_(2)O_(4)的扩散系数为1.4×10^(-5)cm^(2)/s,在1.34~1.42 V下通过Tafel外推法得到H_(2)C_(2)O_(4)电化学氧化的交换电流密度为5.8×10^(-6)A/cm^(2)。
In order to understand the electrochemical oxidation mechanism of oxalic acid on platinum,glassy carbon and boron doped diamond(BDD)electrodes in nitric acid medium,cyclic voltammetry and linear sweep voltammetry were used to carry out electrochemical tests.The effects of electrode potential,current density and nitric acid concentration on oxalic acid oxidation were studied,and the influence of nitric acid mainly comes from H+.On the Pt electrode,it is speculated that oxalic acid is not only electrooxidized,but also adsorbed·OH reacts with adsorbed oxalic acid to produce CO_(2)and H_(2)O.On the boron doped diamond electrode,indirect oxidation of·OH is the main role of oxalic acid oxidation.The increase of nitric acid concentration reduces the amount of·OH production,which leads to the decrease of oxalic acid oxidation rate.On the glassy carbon electrode,the diffusion coefficient of oxalic acid is 1.4×10^(-5)cm^(2)/s measured by rotating disc electrode,the exchange current density of oxalic acid electrochemical oxidation obtained by Tafel extrapolation at 1.34-1.42 V is 5.8×10^(-6)A/cm^(2).
作者
乔璐
张虎
QIAO Lu;ZHANG Hu(China Institute of Atomic Energy,P.O.Box 275(26),Beijing 102413,China)
出处
《核化学与放射化学》
CAS
CSCD
北大核心
2023年第4期295-305,共11页
Journal of Nuclear and Radiochemistry
基金
国家自然科学基金项目(U1867205)。
