氢气在贮氢合金电极上析出反应机理的研究

Abstract

贮氢合金电极上氢气的析出反应分为水分子的放电和吸附氢原子复合脱附两个步骤，即反应按ＶｏｌｍｅｒＴａｆｅｌ机理进行．反应的超电势η可以区分为η１和η２两个组成部分（η＝η１＋η２），反映了Ｖｏｌｍｅｒ和Ｔａｆｅｌ反应的极化特征．析氢反应的速度由二者混合控制，在高超电势区，主要则由Ｖｏｌｍｅｒ反应所控制．反应的法拉第阻抗也同样取决于界面放电Ｖｏｌｍｅｒ反应．交换电流密度为～１０－６Ａ·ｃｍ－２，说明贮氢电极在氢反应中的催化活性与金属镍电极相当．

The hydrogen evolution reaction was studied in 1 mol/L KOH solution on the hydrogen storage alloy Mm(NiCoMnAl) 5 electrode using open circuit potential decay and ac impedance technique. The reaction was found to proceed by the Volmer(discharge)-Tafel(recombination)mechanism. The measured overpotential η can be subdivided into two components η 1 and η 2 corresponding to the elementary Volmer and Tafel reaction. The Faradaic impedance was analyzed and characterized by the Volmer reaction. Then the exchange current density was evaluated . It was founded that the activity of hydrogen storage alloy electrode for the hydrogen evolution reaction was similar to that of Ni electrode.