Adnan Ariba, Behjati Saeid, Félez-Guerrero Núria, Ojha Kasinath, Koper Marc T M
Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden 2333 CC, The Netherlands.
Chemistry Department, Universitat Autònoma de Barcelona, Bellaterra-08193, Barcelona, Spain.
Phys Chem Chem Phys. 2024 Aug 14;26(32):21419-21428. doi: 10.1039/d4cp02133a.
We examined the electric double-layer (EDL) of a Au(111) electrode in a dilute perchloric acid solution using a combination of capacitance measurements and scanning tunnelling microscopy under electrochemical conditions (ECSTM). The "camel-shaped" capacitance curve of the EDL is studied with different cations and anions, including their impact on the potential of zero charge (PZC). We show that the ECSTM images of thermally reconstructed and of the potential-induced surface reconstruction of Au(111) in perchloric acid electrolyte resemble previous work in sulphuric acid, displaying a herringbone pattern for a thermally reconstructed surface. Once the reconstruction is lifted, the Au(111) forms islands with an average of 1 atomic step height. When the potential is lowered below that of the PZC, the potential-induced surface reconstruction results in a more disoriented pattern than the thermally reconstructed surface. ECSTM images at different potentials are correlated with the voltammogram to understand the time and potential dependence of the surface. This correlation has led to the development of a potential window technique that can be used to reveal the surface structure of Au(111) based on observing the changes in PZC in the voltammogram. This method provides an indirect approach to understanding the surface structure without always relying on ECSTM. From the voltammogram, we also observed that anions (SO, CHSO, ClO, F) interact more strongly with the Au(111) surface than the alkali cations. The cation capacitance peak shape does not depend strongly on the identity of the alkali metal cation (Li, Na, K). However, the anion capacitance peak depends strongly on the anion identity. It suggests that some level of specific adsorption cannot be excluded, even for anions that are traditionally not considered to adsorb specifically (perchlorate, fluoride).
我们结合电容测量和电化学条件下的扫描隧道显微镜（ECSTM），研究了稀高氯酸溶液中Au(111)电极的双电层（EDL）。研究了不同阳离子和阴离子存在时EDL的“驼峰状”电容曲线，包括它们对零电荷电位（PZC）的影响。我们发现，在高氯酸电解质中，热重构的以及电位诱导的Au(111)表面重构的ECSTM图像与先前在硫酸中的工作类似，热重构表面呈现出一种人字形图案。一旦重构消失，Au(111)会形成平均具有1个原子台阶高度的岛状结构。当电位降低到PZC以下时，电位诱导的表面重构会导致比热重构表面更无序的图案。不同电位下的ECSTM图像与伏安图相关联，以了解表面的时间和电位依赖性。这种关联促成了一种电位窗口技术的发展，该技术可用于基于观察伏安图中PZC的变化来揭示Au(111)的表面结构。这种方法提供了一种间接途径来理解表面结构，而不必总是依赖于ECSTM。从伏安图中我们还观察到，阴离子（SO、CHSO、ClO⁻、F⁻）与Au(111)表面的相互作用比碱金属阳离子更强。阳离子电容峰的形状并不强烈依赖于碱金属阳离子（Li⁺、Na⁺、K⁺）的种类。然而，阴离子电容峰强烈依赖于阴离子的种类。这表明即使对于传统上不被认为会发生特异性吸附的阴离子（高氯酸盐、氟化物），也不能排除一定程度的特异性吸附。
