摘要
本文介绍一种由各自质子交换膜(作为电解质),参比电极和对电极在同一个工作电极上建立两个空间分离的、可独立控制的双电解池系统.它能够由第1个恒电位仪控制的第1电解池的工作电极产生某种吸附中间物,该中间物通过表面扩散到达第2个电解池的工作电极后,在第2个恒电位仪的控制下得到电化学检验.应用这一装置测量了铂电极上欠电势沉积的含氧吸附物种的表面扩散系数,并研究模拟铂钌电极电氧化有机小分子产生的毒性中间物与表面含氧吸附物种的相互作用.在质子交换膜燃料电池的燃料极的工作电势下,没有发现钌表面产生的含氧吸附物种扩散到铂的表面.作者据此假设Pt Ru协同催化作用的实现可能是由于铂上毒性中间物的表面扩散速率非常慢,限制了向钌表面的溢流速率.只有当Pt Ru边界足够大,中间物在铂表面扩散途径非常短时才能形成足够的流速,并在钌表面被表面含氧物种氧化成CO2,使铂表面被重新活化.
Two local electrochemical reactive interfaces are established using two strips of Nafion~ membrane separated each other, which are in contact with different surface regions of the same metal-sheet working electrode. One potentiostatis used to control thepotentialof one electrochemical reactive interface to generate adsorbed surface speciesand the other potentiostatto hold the potential of the second interface as a detector of the intermediate. The adsorbed surface species driven by the difference in surface concentration diffuses alongthe surface of the metal-sheet between both local electrochemical interfaces and can be detected at the second interface when they achieveover there.The surface diffusion coefficient of the oxygen-containing surface species on Pt was measured, then the synergisticcatalysis was studied using a simplified model Pt-Ru electrode and the spillover of OH_(ads)from the surface of Pt to the surface of Ru was not found in the experimental potential region. This would be explained asthat the realization of synergistic effect is due to spillover of the toxic adsorbed intermediate CO_(ads)on Pt to the surface of Ru and CO_(ads) is oxidized into CO_(2 )by the oxygen-containing surface species over there.
出处
《电化学》
CAS
CSCD
2004年第3期287-292,共6页
Journal of Electrochemistry
基金
国家自然科学基金项目 (2 0 2 73 0 48)资助
