Slesinska Sylwia, Galek Przemysław, Menzel Jakub, Donne Scott W, Fic Krzysztof, Płatek-Mielczarek Anetta
Poznan University of Technology, Institute of Chemistry and Technical Electrochemistry, Berdychowo 4, Poznan, 60965, Poland.
Discipline of Chemistry, University of Newcastle, Callaghan, New South Wales, 2308, Australia.
Adv Sci (Weinh). 2024 Dec;11(48):e2409162. doi: 10.1002/advs.202409162. Epub 2024 Nov 13.
The point of zero charge (PZC) is a crucial parameter for investigating the charge storage mechanisms in energy storage systems at the molecular level. This paper presents findings from three different electrochemical techniques, compared for the first time: cyclic voltammetry (CV), staircase potentio electrochemical impedance spectroscopy (SPEIS), and step potential electrochemical spectroscopy (SPECS), for two activated carbons (ACs) with 0.1 mol L aqueous solution of LiNO, LiSO, and KI. The charging process of AC operating in aqueous electrolytes appears as a complex phenomenon - all ionic species take an active part in electric double-layer formation and the ion-mixing zone covers a wide potential region. Therefore, the so-called PZC should not be considered as an absolute one-point potential value, but rather as a range of zero charge (RZC). SPECS technique is found to be a universal and fast method for determining RZC, as applied here together with the EQCM. In most cases, the RZC covers a potential range from ≈100 to ≈200 mV and the correlation of the range with the carbon microtexture is clear, highlighting the role of the ion-sieving effect. It is postulated that PZC for porous materials in aqueous electrolytic solutions should be considered instead as RZC.
零电荷点（PZC）是在分子水平上研究储能系统中电荷存储机制的关键参数。本文首次比较了三种不同的电化学技术所得结果：循环伏安法（CV）、阶梯电位电化学阻抗谱（SPEIS）和阶跃电位电化学谱（SPECS），研究对象是两种活性炭（AC），电解液为0.1 mol/L的LiNO、LiSO和KI水溶液。在水性电解质中运行的活性炭的充电过程表现为一种复杂现象——所有离子物种都积极参与双电层的形成，且离子混合区覆盖较宽的电位范围。因此，所谓的PZC不应被视为一个绝对的单点电位值，而应被视为一个零电荷范围（RZC）。发现SPECS技术是一种通用且快速测定RZC的方法，本文将其与石英晶体微天平（EQCM）一起应用。在大多数情况下，RZC覆盖的电位范围约为100至约200 mV，该范围与碳微观结构的相关性明显，突出了离子筛分效应的作用。据推测，对于在水性电解液中的多孔材料，应将PZC视为RZC。
