铂单晶电极表面不可逆反应动力学(Ⅲ)

Kinetics of Irreversible Reactions on Platinum Single Crystal Electrodes(Ⅲ)

在本系列研究论文Ⅰ[1]和Ⅱ[2]报导的结果基础上，进一步发展动力学数据解析方法．通过改变反应体系的温度，首次获得甲酸在Pt（100），Pt（110），Pt（111）电极上直接氧化反应的表观活化Gibbs自由能（△G≠0）．在实验选定的标准状态下，即0．0V／SCE、298．15K和1．013×105Pa下，来算得到。还发现传递系数β在实验温度范围（283．15～303．15K）不随温度变化，但随电极表面原子排列结构变化，大小次序与△G≠0的变化一致．

Based on results of the lst and 2nd papers of the present studies, the procedure of data processing was developed further. Through the variation of the temperature of the reaction system the apparent Gibbs free energy of activation (△G≠0) for direct oxidation of HCOOH on Pt(100),Pt(111) aud Pt(110) single crystal electrodes was obtained for the first time. Under the standard states defined in the present study i.e, at 0.0V/SCE.298.15K alld 1.013×105Pa, the apparent Gibbs free energy of activatiou for HCOOH oxidation has been evaluated as 32.2±0.5 kJ.mol-1 on Pt(100), 25.8±0.4 kJ·mol-1 on Pt(111) and 10.1±0.2 kJ·mol-1 on Pt(110), respectively. It has been found that the transfer coefficieut (β) of HCOOH oxidation is independent of temperature in the range between 283.15 ~ 303.15K, but varies with the surtace atomc arrangement of Pt siugle crystal electrode and yields the same variation order as that of the apparent Gibbs frec energy of activation.