多晶铂电极电催化氧化苯酚的电化学过程

采用循环伏安(CV)、Tafel曲线、交流阻抗(EIS)等方法研究苯酚在多晶铂电极上的电氧化过程.在扫描速度分别为10 mV/s、20 mV/s、50 mV/s、100 mV/s和200 mV/s时,以0.25 mol/L的Na2SO4为支持电解质,考查500 mg/L苯酚在铂电极上氧化的CV曲线变化规律.测试表明发生了不可逆的电氧化反应,氧化峰位置为0.926 V(vs.Ag/AgC l,扫描速度50 mV/s,).苯酚氧化峰电流值与CV扫描速率的关系表明苯酚的氧化反应是由扩散过程和吸附过程共同控制的电化学氧化过程.分别选用0.1和1.0 mol/L的H2SO4溶液为电解液,测试Pt电极析氧反应的Tafel曲线,Tafel斜率为149 mV.采用EIS分析苯酚的电氧化反应,结果表明在高频段存在苯酚吸附的特征容抗弧.

Study of the oxidation of phenol at the poly-tropism platinum electrode

The process of electrochemical oxidation of phenol on the poly-tropism platinum electrode has been investigated by electrochemical methods such as cyclic voltammetry,Tafel curves and electrochemical impedance spectra technique.The cyclic voltammograms were measured with several potential sweep rates of 10,20,50,100 and 200 mV/s,using 0.25 mol/L Na2SO4 as sustained electrolyte.The regular of cyclic voltammograms of 500 mg/L phenol oxidation on the Pt electrode was further studied.It was indicated that electrochemical oxidation of phenol on platinum electrode was irreversible process and the oxidation peak appeared at 0.926 V(vs.Ag/AgCl) with the scanning rate of 50 mV/s.Furthermore,the dependence of the phenol oxidation peak current on the CV scanning rate was also studied and it could be concluded that the phenol oxidation process was controlled by electrochemical oxidation process of the diffusion and adsorption step.The Tafel curves were measured in 0.1 and 1.0 mol/L H2SO4 solution,respectively.The Tafel curves were used to analyze the Pt electrode oxygen evolution reaction and the slope of the Tafel curve is 149 mV.Electrochemical impedance spectra technique was used to studied phenol electrochemical oxidation reaction,and a semicircle of capacitor resistance was shown in EIS due to the phenol adsorption in high frequency.