通过电化学微量热法鉴定电化学吸附物种：硫酸盐在Au(111)上的吸附

Identification of Electrochemically Adsorbed Species via Electrochemical Microcalorimetry: Sulfate Adsorption on Au(111).

作者信息

Schönig Marco, Frittmann Stefan, Schuster Rolf

机构信息

Institute of Physical Chemistry, Karlsruhe Institute of Technology, Kaiserstraße 12, 76131, Karlsruhe, Germany.

出版信息

Chemphyschem. 2022 Sep 5;23(17):e202200227. doi: 10.1002/cphc.202200227. Epub 2022 Jul 5.

DOI:10.1002/cphc.202200227

PMID:35510390

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC9542382/

Abstract

We investigate compositional changes of an electrochemical interface upon polarization with electrochemical microcalorimetry. From the heat exchanged at a Au(111) electrode upon sulfate adsorption, we determine the reaction entropy of the adsorption process for both neutral and acidic solutions, where the dominant species in solution changes from SO to HSO . In neutral solution, the reaction entropy is about 40 J mol K more positive than that in acidic solution over the complete sulfate adsorption region. This entropy offset is explicable by a deprotonation step of HSO preceding sulfate adsorption in acidic solution, which shows that the adsorbing species is SO * in both solutions. The observed overall variation of the reaction entropy in the sulfate adsorption region of ca. 80 J mol K indicates significant sulfate-coverage dependent entropic contributions to the Free Enthalpy of the surface system.

摘要

我们用电化学微量热法研究了极化时电化学界面的组成变化。通过在金（111）电极上吸附硫酸盐时交换的热量，我们确定了中性和酸性溶液中吸附过程的反应熵，其中溶液中的主要物种从硫酸根变为硫酸氢根。在中性溶液中，在整个硫酸盐吸附区域内，反应熵比酸性溶液中的反应熵约正40 J mol⁻¹ K⁻¹。这种熵偏移可以通过酸性溶液中硫酸氢根在硫酸盐吸附之前的去质子化步骤来解释，这表明在两种溶液中吸附物种均为硫酸根*。在约80 J mol⁻¹ K⁻¹的硫酸盐吸附区域内观察到的反应熵的整体变化表明，硫酸盐覆盖度对表面系统的自由焓有显著的熵贡献。