Correlation of surface site formation to nanoisland growth in the electrochemical roughening of Pt(111)

Abstract

Platinum plays a central role in a variety of electrochemical devices and its practical use depends on the prevention of electrode degradation. However, understanding the underlying atomic processes under conditions of repeated oxidation and reduction inducing irreversible surface structure changes has proved challenging. Here, we examine the correlation between the evolution of the electrochemical signal of Pt(111) and its surface roughening by simultaneously performing cyclic voltammetry and in situ electrochemical scanning tunnelling microscopy (EC-STM). We identify a 'nucleation and early growth' regime of nanoisland formation, and a 'late growth' regime after island coalescence, which continues up to at least 170 cycles. The correlation analysis shows that each step site that is created in the 'late growth' regime contributes equally strongly to both the electrochemical and the roughness evolution. In contrast, in the 'nucleation and early growth' regime, created step sites contribute to the roughness, but not to the electrochemical signal.

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

“…To verify the correctness of the model, we compared the simulated curves with experimental curves in Figure S2 at other scanning rates of 0.002, 0.02, 0.1 and 1 V s À 1 . [7] Figure 4 shows the CVs with different upper potentials from 0.45 to 1.15 V with an interval of 0.1 V at the scan rate of 0.05 V s À 1 . Figure 3 shows the simulated CV curves at different scan rates.…”

“…The electrochemistry of Pt materials is critical in both electrooxidation of fuels and electroreduction of dioxygen. [7][8][9] It is very important to understand the surface chemistry of Pt for fuel cells. [3,6] For the cathodic reaction of oxygen reduction reaction, Pt materials could be undermined by the irreversible surface change and Pt dissolution with intensive cycling.…”

“…Much qualitative information of surface species can be extracted from CV combined with in situ surface technics such as Fourier Transformation Infrared Spectroscopy (FTIR), [10,11] Raman spectroscopy, [12] scanning tunneling microscopy (STM), [7,9] and surface X-ray scattering. Much qualitative information of surface species can be extracted from CV combined with in situ surface technics such as Fourier Transformation Infrared Spectroscopy (FTIR), [10,11] Raman spectroscopy, [12] scanning tunneling microscopy (STM), [7,9] and surface X-ray scattering.…”

“…[14,15] To well understand the behavior of Pt polycrystal, Pt(111) electrode was used as a model electrode due to its most thermodynamically stability among all the facets of Pt crystal. [7,12] Two typical CVs of Pt(111) with different upper potentials in HClO 4 electrolyte are shown in Figure 1. Feliu group investigated the influences of potential scan rate, temperature, upper limit potential, electrolyte, and pH on the CV shapes at Pt(111) electrode and proposed kinetics models to illustrate the mechanisms underlying the observed CV curves.…”

“…Feliu group investigated the influences of potential scan rate, temperature, upper limit potential, electrolyte, and pH on the CV shapes at Pt(111) electrode and proposed kinetics models to illustrate the mechanisms underlying the observed CV curves. [7,12,15,[27][28][29] Rinaldo et al proposed a series of elementary reactions and applied the Butler-Volmer equations to simulate the CVs between 0.65 and 1.15 V. [30] However, a small cathodic peak around 1.05 V cannot be simulated at high scan rates, indicating that the proposed kinetics model should have room to be improved. [7,12] Two typical CVs of Pt(111) with different upper potentials in HClO 4 electrolyte are shown in Figure 1.…”