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Abstract：
We describe two operating modes for the same potentiostat, where the redox processes of hydroquinone in a hydrochloric acid medium are contrasted for cyclic voltammetry (CV) as functions of a digital/staircase scan and an analogue/linear scan. Although superficially there is not much to separate the two modes of operation as an end user, differences can be seen in the voltammograms while switching between the digital and analogue modes. The effects of quantization clearly have some impact on the measurements, with the outputs between the two modes being a function of the equivalent-circuit model of the electrochemical system under investigation. Increasing scan rates when using both modes produces higher peak redox currents, with the differences between the analogue and digital modes of operation being consistent as a function of the scan rate. Differences between the CV loops between the analogue and digital modes show key differences at certain points along the scans, which can be attributed to the nature of the electrolyte affecting the charging and discharging processes and consequently changing the peak currents of the redox processes. The faradaic processes were shown to be independent of the scan rates. Simulations of the equivalent-circuit behaviour show differences in the responses to different input signals, i.e., the step and ramp responses of the system. Both the voltage and current steps and ramp responses showed the time-domain behaviour of distinct elements of the equivalent electrochemical circuit model as an approximation of the applied digital and analogue CV input signals. Ultimately, it was concluded that similar parameters between the two modes of operation available with the potentiostat would lead to different output voltammograms and, despite advances in technology, digital systems can never fully emulate a true analogue system for electrochemical applications. These observations showcase the value of having hardware capable of true analogue characteristics over digital systems.
摘要：
我们描述了同一恒电位仪的两种操作模式，其中氢醌在盐酸介质中的氧化还原过程与循环伏安法（CV）作为数字/阶梯扫描和模拟/线性扫描的函数进行了对比。尽管从表面上看，作为最终用户的两种操作模式没有太多区别，在数字和模拟模式之间切换时，可以在伏安图中看到差异。量化的效果显然对测量有一些影响，两种模式之间的输出是所研究的电化学系统的等效电路模型的函数。使用两种模式时增加扫描速率会产生更高的峰值氧化还原电流，模拟和数字操作模式之间的差异作为扫描速率的函数是一致的。模拟和数字模式之间的CV循环之间的差异显示扫描过程中某些点的关键差异，这可以归因于电解质的性质影响充电和放电过程并因此改变氧化还原过程的峰值电流。法拉第过程显示与扫描速率无关。等效电路行为的仿真显示了对不同输入信号的响应差异，即，系统的阶跃和斜坡响应。电压和电流阶跃以及斜坡响应均显示了等效电化学电路模型的不同元素的时域行为，作为所施加的数字和模拟CV输入信号的近似值。最终,结论是，使用恒电位仪的两种操作模式之间的相似参数将导致不同的输出伏安图，尽管技术进步，数字系统永远无法完全模拟电化学应用的真正模拟系统。这些观察结果展示了在数字系统上具有真正模拟特性的硬件的价值。
