Mechanistic Insights into Cyclic Voltammograms on Pt(111): Kinetics Simulations

Abstract

A detailed understanding of the electrochemistry of platinum electrodes is of great importance for the electrochemical oxidation of fuels and electrochemical reduction of dioxygen in fuel cells. The Pt(111) facet is the most representative model mimicking Pt nanoparticles and polycrystals for fundamental studies. Herein, we propose a site-specific model accompanied with the typical elementary steps of the electrochemistry of Pt (111) in non-adsorbing electrolyte within the potential range between 0.05 and 1.15 V versus reversible hydrogen electrode. Simulations were conducted at different scanning rates based on the kinetics models. We reproduce all the anodic and cathodic peaks observed in the reported experimental curves. These results demonstrate the underlying mechanisms of the peak formation in different potential regions.probably affects the surface reactions. In the current simplified model, mass transfer was not considered. However, the trend of peak shifting is the same with experimental data, which is sufficient and reasonable to do qualitative analyses. Compared Figure 2. Comparison of the simulated (red solid) with experimental (blue dashed) CV curves (a, c, e, g). The experimental data were extracted from the reference. [29] The coverage of the surface species corresponding to the simulated CV curves at different scan rates: (b) 0.005 V s À 1 , (d) 0.05 V s À 1 , (f) 0.5 V s À 1 , (h) 5 V s À 1 . Each curve in a color contains the forward and backward scan labeled with arrow. In the case of the curve without arrow, the forward and backward scans overlap.

Surface Extraction Process During Initial Oxidation of Pt(111): Effect of Hydrophilic/Hydrophobic Cations in Alkaline Media

“…The assignment of the P2 and P3 peaks is controversial because of the complex adsorbate structure generated during the oxide formation. Computational simulations and ex situ X- 57,58 However, the simulations were performed considering acidic conditions. In alkaline solutions, the potentials and intensities of the P2 and P3 peaks of Pt(111) notably depend on the electrolyte cations.…”

“…The assignment of the P2 and P3 peaks is controversial because of the complex adsorbate structure generated during the oxide formation. Computational simulations and ex situ X-ray photoelectron spectroscopy (XPS) experiments suggested the stable coexistence of H 2 O ad , OH ad , or O ad on Pt surfaces due to simultaneous or sequential oxide formation. − Simulations of voltammetric curves based on kinetic modeling indicated that the second anodic peak above 0.9 V corresponds to Pt–O ad (Pt–OH ad → Pt–O ad + H + + e – ) on several different adsorption sites, e.g., top, bridge, and hollow sites of Pt(111). , However, the simulations were performed considering acidic conditions. In alkaline solutions, the potentials and intensities of the P2 and P3 peaks of Pt(111) notably depend on the electrolyte cations. , The apparent separation of the P2 and P3 peaks in TMAOH compared to that in alkali metal hydroxides deserves particular attention.…”