Shin Sunghwan, Greco Francesco, Maier Florian, Steinrück Hans-Peter
Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany.
Phys Chem Chem Phys. 2021 May 14;23(18):10756-10762. doi: 10.1039/d0cp04811a. Epub 2021 Mar 26.
The behavior of ionic liquids (ILs) at charged interfaces is pivotal for their application in supercapacitors and electrochemical cells. Recently, we demonstrated for neat ILs that potential screening at polarized electrode interfaces shows a characteristic voltage dependence, as determined in situ by X-ray photoelectron spectroscopy. Herein, we use this fingerprint-type behavior to characterize the nature of the IL/electrode interfaces for IL mixtures of [CCIm][TfN] and [CCIm]Cl on Au and Pt electrodes. For Au, the IL/electrode interfaces are dominated by the Cl anions, even down to a 0.1 mol% [CCIm]Cl content. In contrast, [TfN] anions enrich at the IL/Pt electrode interfaces down to 10 mol% [CCIm][TfN]; only at lower concentrations does a transition to Cl enrichment occur. These mixture studies demonstrate that even small concentrations of another IL or contamination, e.g. remaining from synthesis, can strongly influence the situation at charged IL interfaces.
离子液体（ILs）在带电界面的行为对于其在超级电容器和电化学电池中的应用至关重要。最近，我们针对纯离子液体证明，极化电极界面处的电位筛选呈现出特征性的电压依赖性，这是通过X射线光电子能谱原位测定的。在此，我们利用这种指纹型行为来表征在金电极和铂电极上的[CCIm][TfN]与[CCIm]Cl离子液体混合物的IL/电极界面的性质。对于金电极，即使[CCIm]Cl含量低至0.1 mol%，IL/电极界面也以Cl阴离子为主导。相比之下，在IL/Pt电极界面，[TfN]阴离子富集至[CCIm][TfN]含量低至10 mol%；只有在更低浓度时才会转变为Cl富集。这些混合物研究表明，即使是另一种离子液体的低浓度或污染物（例如合成过程中残留的）也会强烈影响带电IL界面的情况。
