使用Kelvin探头参比电极技术研究液层厚度对氧还原速度的影响

AN INVESTIGATION ON OXYGEN REDUCTION UNDER THIN ELECTROLYTE LAYER USING KELVIN PROBE REFERENCE ELECTRODE

使用Ｋｅｌｖｉｎ探头参比电极技术研究了薄液层下氧还原过程的特征。实验中发现随着液层的蒸发减薄，氧还原反应速度先逐渐增加，而后又逐渐降低，呈现出速度极大值现象。尽管溶液中氧的盐效应对氧还原速度可能有一定的影响，实验结果表明，它并不是造成氧还原速度降低的主要原因。随着液层厚度的减薄，开始是氧扩散速度的增加加速了氧还原反应速度，随后是气／液界面上氧气溶解速度抑制了氧还原速度的增加。当液层很薄时，金属表面液层阴极电流的不均匀分布导致了氧还原速度的迅速下降。

An electrochemical investigation on the oxygen reduction under thin electrolyte layer was made usingKelvin probe as reference electrode.It was found that as the electrolyte layer thickness decreased duringelectrolyte evaporation,the rate of oxygen reduction first increased,then stagnated and finally decreased,thus showing a maximum.Althougy oxygen salting out effect had some influence on the rate of oxygenreduction,it was not main cause responsible for the decrease in cathodic limiting current in the case ofvery thin electrolyte layer. With decreasing water layer thickness upon drying, the oxygen reduction ratewas in trun accelerated by the faster oxygen diffusion, hindered by the limited rate of oxygen dissolutionat the gas/liquid interface, and reduced due to nonuniform current distribution on electrode surface as thewater layer thickness became very thin.