Deconvolution of the Voltammetric Features of a Pt(100) Single-Crystal Electrode

Xiaoting Chen; Kasinath Ojha; Marc T M Koper

doi:10.1021/acs.jpclett.4c01056

Deconvolution of the Voltammetric Features of a Pt(100) Single-Crystal Electrode

J Phys Chem Lett. 2024 May 9;15(18):4958-4964. doi: 10.1021/acs.jpclett.4c01056. Epub 2024 Apr 30.

Authors

Xiaoting Chen^{1

2}, Kasinath Ojha², Marc T M Koper²

Affiliations

¹ School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China.
² Leiden Institute of Chemistry, Leiden University, P. O. Box 9502, 2300 RA, Leiden, The Netherlands.

Abstract

The Pt(100) single-crystal electrode shows four voltammetric features in acid electrolytes, but the precise corresponding surface phenomena remain unresolved. Herein, a deconvolution of the classical "hydrogen region" from the "hydroxyl and anion region" is attempted by the comparison of voltammetric behavior of Pt(100) and G_MLPt(100) electrodes. A systematic study performed on Pt(s)-[n(100) × (111)] and Pt(s)-[n(100) × (110)] electrodes reveals that the feature at E_PI = 0.30 V_RHE corresponds to pure hydrogen adsorption taking place at (111) step sites vicinal to (100) domains, while the peak at E_PII = 0.36 V_RHE actually involves hydroxyl replacing hydrogen at (100) domains. An analysis examined for H₂SO₄, HClO₄, CH₃SO₃H, and HF demonstrates that the specific (H)SO₄^- adsorption commences at E_PIII = 0.40 V_RHE and effectively suppresses the formation of hydroxyl at the (100) terrace at higher potentials 0.40 < E_PIV < 0.75 V_RHE. Non-specifically adsorbing anions (ClO₄^-, CH₃SO₃^- and F^-) would only interact with the hydroxyl phase formed on the Pt(100) terrace in both potential regions.