蔡启瑞讲座
报告题目：Delay in Kinetics by Frequency-Dispersion of EDL Capacitance
报告时间：2026-10-20 15:30
报告人：Professor Koichi Jeremiah Aoki
University of Fukui
报告地点：翔安校区能源材料大楼3号会议室3
报告摘要：
Electric double layer capacitance is a basic concept for developing supercapacitors of rapid electric storage. It is caused by field-orientation of solvent dipoles with help of ions. It is almost independent of voltage as well as ionic concentrations, being different from the prediction of Gouy-Chapman's theory. The values get smaller at higher frequency of ac voltage, called frequency dispersion, which has been represented by the constant phase element or the power-law of frequency. Values of the capacitance vary with electrochemical techniques such as AC-impedance, cyclic voltammetry and chronoamperometry. Experimental data are shown, supported by the theoretical background.
Orientation of a dipole by an external field takes pico-second order, but the observed response time is mill second or second order. The delay can be explained by long distant interaction on an electrode surface, like 2D-crystalline water structure. Computation of the Ising model of dipoles supports the power-law.
When positive charge is formed on an electrode by oxidation, a solvent dipole turns the negative end toward the positive electrode charge. Then, the oxidation increases the net field or decreases both the capacitance and the capacitive current. The net faradaic current should be small as if kinetics might block the reaction. The frequency dispersion mimics electrode kinetics. This can explain the fact that fast voltammetric data always exhibit kinetic delay although steady-state voltammetry at ultramicroelectrodes shows the reversible reactions.
报告人简介：
Koichi Jeremiah Aoki is an Emeritus Professor of Applied Physics at the University of Fukui. He received his Ph.D. from Tokyo Institute of Technology and conducted postdoctoral research in the USA. His research focuses on fundamental electrochemistry and physical chemistry, including electric double layers, microelectrode voltammetry, interfacial mass transport, and charge transfer kinetics. He has published over 300 peer-reviewed papers and a specialized monograph. As a recipient of the Sano Medal, he has served as a journal editorial board member and organized numerous international academic conferences, being a distinguished scholar in electroanalytical chemistry.
欢迎老师同学们积极参加!
化学化工学院
表界面化学全国重点实验室
