Initial stages of Pt(111) electrooxidation: dynamic and structural studies by surface X-ray diffraction

Abstract

In-situ surface X-ray diffraction is used to characterize the surface oxides on Pt(111) surface in 0.1 M HClO 4. Detailed analysis at two potentials confirms that the surface restructuring at the initial oxidation stages is consistent with a place exchange process between Pt and O atoms, and the exchanged Pt atoms are located above their original positions in the Pt(111) lattice. The (1,1,1.5) reflection is used to dynamically study the surface during cyclic voltammetry. The restructuring associated with the place exchange initiates with the CV peak at 1.05 V, even though multiple cycles to 1.17 V lead to no changes in the CV. The restructuring is reversible below a critical coverage of place exchanged Pt atoms, which we estimate to be between 0.07 and 0.15 ML. Extensive cycling to potentials higher or equal to 1.17 V leads to progressive disordering of the surface.

Potential Dependence of Pt and Co Dissolution from Platinum-Cobalt Alloy PEFC Catalysts Using Time-Resolved Measurements

“…[27][28][29][30][31][32][33][34] As an extension of our previous work, 5 we consider a non-ideal solid solution of Pt and hydroxide/oxides whose composition can be determined by considering the following reactions, which are supported by experimental evidence from the extensive Pt oxidation literature. PtOH…”

Elucidation of Activity Enhancement Factors for the Oxygen Reduction Reaction on Platinum and Palladium Single Crystal Electrodes

“…In-situ SXD revealed that site exchange of Pt and O occurs at 1.1 V(RHE) on Pt(111). 21 There have been no study on Pt oxides using in-situ vibrational spectroscopy on well-defined single crystal electrodes. In this section, we summarize our recent studies of Pt oxides on single crystal electrodes of Pt using IRAS and NPSERS.…”

“…75 However, the onset potential of PtO and PtO(H) formation in NPSERS is 1.15 V(RHE) where coverage of PtO reaches full coverage and place exchange occurs between Pt and O. 21 Strong electric field of plasmon may expel PtO from the neighborhood of Au nanoparticles at lower coverage of PtO. 74 Figure 13 shows the integrated band intensity of NPSERS plotted against the applied potentials.…”

“…Real atomic arrangements of single crystal electrodes were studied in electrochemical environments using STM and surface X-ray diffraction (SXD). Pt(111) 4,[19][20][21] and Pt(100) [22][23][24] have unreconstructed (1 © 1) structures in adsorbed hydrogen and double layer regions. Above 1.05 V(RHE), however, irreversible place exchange of oxygen species and Pt atoms is observed on Pt(111).…”

“…Above 1.05 V(RHE), however, irreversible place exchange of oxygen species and Pt atoms is observed on Pt(111). 21 Bare Pt(110) has reconstructed (1 © 2) structure 0.1 M KOH, 0.1 M H 2 SO 4 , and 0.1 M HClO 4 according to SXD study. 25 There is a report that (1 © 1) and (1 © 2) structure of Pt(110) can be controlled by the change of annealing and cooling condition.…”