Ganassin Alberto, Sebastián Paula, Climent Víctor, Schuhmann Wolfgang, Bandarenka Aliaksandr S, Feliu Juan
Analytical Chemistry - Center for Electrochemical Sciences (CES), Ruhr-Universität Bochum, Universitätsstr, 150, 44780, Bochum, Germany.
Instituto de Electroquímica, Universidad de Alicante, Apartado 99, E-03080, Alicante, España, Spain.
Sci Rep. 2017 Apr 28;7(1):1246. doi: 10.1038/s41598-017-01295-1.
Studies over the entropy of components forming the electrode/electrolyte interface can give fundamental insights into the properties of electrified interphases. In particular, the potential where the entropy of formation of the double layer is maximal (potential of maximum entropy, PME) is an important parameter for the characterization of electrochemical systems. Indeed, this parameter determines the majority of electrode processes. In this work, we determine PMEs for Ir(111) electrodes. The latter currently play an important role to understand electrocatalysis for energy provision; and at the same time, iridium is one of the most stable metals against corrosion. For the experiments, we used a combination of the laser induced potential transient to determine the PME, and CO charge-displacement to determine the potentials of zero total charge, (E). Both PME and E were assessed for perchlorate solutions in the pH range from 1 to 4. Surprisingly, we found that those are located in the potential region where the adsorption of hydrogen and hydroxyl species takes place, respectively. The PMEs demonstrated a shift by ~30 mV per a pH unit (in the RHE scale). Connections between the PME and electrocatalytic properties of the electrode surface are discussed.
对构成电极/电解质界面的各组分熵的研究，能够为带电界面的性质提供基本见解。特别是，双层形成熵最大时的电位（最大熵电位，PME）是表征电化学系统的一个重要参数。实际上，这个参数决定了大多数电极过程。在这项工作中，我们测定了Ir(111)电极的PME。Ir(111)电极目前在理解能量供应的电催化过程中起着重要作用；同时，铱是最耐腐蚀的金属之一。在实验中，我们结合使用激光诱导电位瞬变来测定PME，并利用CO电荷位移来测定零总电荷电位（E）。在pH值为1至4的范围内，对高氯酸盐溶液同时评估了PME和E。令人惊讶的是，我们发现它们分别位于氢和羟基物种发生吸附的电位区域。PME在RHE标度下表现出每pH单位约30 mV的偏移。文中讨论了PME与电极表面电催化性能之间的联系。
