电极金属和电解质溶液界面势垒研究

RESEARCH ON THE POTENTIAL ENERGY BARRIER AT THE ELECTRODEELECTROLYTE INTERFACE

本文根据肖特基效应和弗兰克-康东原理得到了近似理想极化电极体系赫姆荷尔茨双电层内势垒高度和宽度与电极电荷密度间的关系式。并用Hg—HCl电极电荷密度的文献值作了具体计算。计算表明,电极电势对电子转移势垒形状的影响是很大的。

It is the centre of electrode kinetics that mechanisms of electron transfer through the interface between metal electrode and electrolyte.According to the classical theory of electrochemistry,the electrode process is one that the electron pass over the potential energy barrier of interface to bond with activate ion.However,quantum electrochemistry recognizes also that the electron may tunneles the energy barrier.If we can know the height and width of the barrier when the electrode process occurs,then,in principle we can determine the way of electron transfer,in terms of the calculation method of Schottky emission and"cold emission".However,the height and width of the barrier cannot be measured experimentally as yet,therefore,it is significant to research in to the energy barrier in theory.In order to describe the shape of the potential barrier,Bockris,Matthews,et al.proposed a potential energy function,which consists of the image energy when an electron leaves the surface of metallic electrode and the Coulomb energy while the electron approaches the activated hydrogen ion.The barrier height obtained from this function is independent of electrode potential.Later,the dependence of the degree of extension of H^(+)-H_(2)O bond on the electrode potential was taken into consideration by Matthews,he obtained the barrier height and width as a function of electrode potential from graphical construction.In the present paper,the strength of electron-field in electrochemical interface is regarded as a function of electrode potential,and the Schottky effect and Frank-Condon principle are applied to obtain the relationship between electrode-charge density and barrier height(H)and barrier width(d)in Helmholtz double-layersIn this paper,we also calculated the barrier height and width of Hg--HC1 electrode system with the formula cited above,the results aretabulated.