基于改进计时电流法精确模型的数值解仿真及实验验证

根据电极表面被测物浓度变化经验公式所建立的改进计时电流法的理论模型,只能定性分析响应电流峰值与被测物浓度关系,无法准确描述响应电流峰值与反应体系及激励电势中其它参数的关系.为解决该问题,利用能斯特方程与扩散定律,建立了描述电极表面被测物浓度与响应电流关系的积分方程,通过数值分析方法求解得到该积分方程数值解.进而利用数值仿真得到精确的电流与时间关系曲线,分析了电流峰值与试剂浓度、惯性时间常数、参比电极标准电势、激励电势初始值以及稳态值之间的关系.最后,利用改进计时电流法的电路装置对K3Fe(CN)6]试剂进行测试,实验结果表明该数值模型比经验模型更接近真实情况,也验证了由该模型推导得到的各参数之间关系的正确性.

Numerical Simulation Based Accurate Models of Improved Chronoamperometry and Its Experimental Validation

Based on the empirical formula for concentration change of a detected molecule on the surface of a electrode,an approximate mathematical model of improved chronoamperometry was established.The relationship between the working current and detection reagent concentration was analyzed qualitatively.Parameters for the electrode reaction and excitation potential were not included.To solve this problem,the Nernst equation and Fick’s law were applied to construct an integral equation for the specific concentrations of the oxidant and reductant on the surface of the electrode.The current-time curve obtained numerically was used to investigate the relationship between the peak current and concentration of reagent,inertia time constant,standard potential of the reference electrode,initial value and steady state value of the voltage excitation.Using the improved chronoamperometry device,we studied the electrochemical behavior of K3Fe(CN)6].The experimental results showed that the simulation results from the numerical model were much closer to the actual situation than the empirical model.The experimental results also confirmed the parameter relationships that were derived using the model.