Issue 35, 2019

Resolving the chemical identity of H2SO4 derived anions on Pt(111) electrodes: they're sulfate

Abstract

Understanding how electrolyte composition controls electrocatalytic reactions requires molecular-level insight into electrode/electrolyte interaction. Perhaps the most basic aspect of this interaction, the speciation of the interfacial ion, is often controversial for even relatively simple systems. For example, for Pt(111) in 0.5 M H2SO4 it has long been debated whether the adsorbed anion is SO42−, HSO4 or an H3O+⋯SO42− ion pair. Here we apply interface-specific vibrational sum frequency (VSF) spectroscopy and theory to this problem and perform an isotope exchange study: we collect VSF spectra of Pt(111) in H2SO4(H2O) and D2SO4(D2O) as a function of bias and show that at all potentials they are identical. This is the most direct spectroscopic evidence to date that SO42− is the dominant adsorbate, despite the fact that at 0.5 M H2SO4 bulk solution is dominated by HSO4. This approach is based on the unique selection rule of the VSF spectroscopy and thus offers a new way of accessing general electrode/electrolyte interaction in electrocatalysis.

Graphical abstract: Resolving the chemical identity of H2SO4 derived anions on Pt(111) electrodes: they're sulfate

Supplementary files

Article information

Article type
Paper
Submitted
16 Jun 2019
Accepted
15 Aug 2019
First published
15 Aug 2019
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2019,21, 19147-19152

Resolving the chemical identity of H2SO4 derived anions on Pt(111) electrodes: they're sulfate

I. Y. Zhang, G. Zwaschka, Z. Wang, M. Wolf, R. K. Campen and Y. Tong, Phys. Chem. Chem. Phys., 2019, 21, 19147 DOI: 10.1039/C9CP03397A

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