Pt oxide and oxygen reduction at Pt(111) studied by surface X-ray diffraction

Drnec, Jakub; Ruge, Martin; Reikowski, Finn; Rahn, Björn; Carlà, Francesco; Felici, Roberto; Stettner, J.; Magnussen, Olaf M.; Harrington, David A.

doi:10.1016/j.elecom.2017.10.002

Cited by 18 publications

(31 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 5a shows the stepwise oxidation of a single layer of Nafion-supported nanoparticles. The onset potential for oxide formation lies between 0.9 V RHE and 1.15 V RHE (in agreement with the literature 10,13−19 ), roughly 0.2 V lower than for Pt/FAD. Note that this shift in oxidation onset is also present for thicker Pt layers on Nafion.…”

Section: Resultssupporting

confidence: 91%

See 1 more Smart Citation

The Oxidation of Platinum under Wet Conditions Observed by Electrochemical X-ray Photoelectron Spectroscopy

et al. 2019

View full text Add to dashboard Cite

During the electrochemical reduction of oxygen, platinum catalysts are often (partially) oxidized. While these platinum oxides are thought to play a crucial role in fuel cell degradation, their nature remains unclear. Here, we studied the electrochemical oxidation of Pt nanoparticles using in situ XPS. When the particles were sandwiched between a graphene sheet and a proton exchange membrane that is wetted from the back, a confined electrolyte layer was formed, allowing us to probe the electrocatalyst under wet conditions. We show that the surface oxide formed at the onset of Pt oxidation has a mixed Pt δ+ /Pt 2+ /Pt 4+ composition. The formation of this surface oxide is suppressed when a Br-containing membrane is chosen due to adsorption of Br on Pt. Time-resolved measurements show that oxidation is fast for nanoparticles: even bulk PtO 2 · n H 2 O growth occurs on the subminute time scale. The fast formation of Pt 4+ species in both surface and bulk oxide form suggests that Pt 4+ -oxides are likely formed (or reduced) even in the transient processes that dominate Pt electrode degradation.

show abstract

Section: Resultssupporting

confidence: 91%

“…The importance of oxygen in the dissolution process suggests that platinum oxides are involved. Indeed, it was shown that the surface of Pt cathodes is (partially) oxidized at ORR potentials, particularly in the presence of oxygen. ,− …”

Section: Introductionmentioning

confidence: 99%

The Oxidation of Platinum under Wet Conditions Observed by Electrochemical X-ray Photoelectron Spectroscopy

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Conventional SXRD studies were performed at beamline ID03 and focused on kinetic studies of the Pt oxidation process by measuring the X-ray intensity at a fixed position along a crystal truncation rod (CTR). Similar as in our previous studies, 17,18,23,24,40 these measurements employed a photon energy of 22.5 keV, a (vert./hor.) beam size of 45×750 µm 2 and an angle of incidence of 0.3 • .…”

Section: Surface X-ray Diffraction Setupmentioning

confidence: 90%

Structure dependency of the atomic-scale mechanisms of platinum electro-oxidation and dissolution

et al. 2020

Self Cite

View full text Add to dashboard Cite

Platinum dissolution and restructuring due to surface oxidation are primary degradation mechanisms that limit the lifetime of Pt-based electrocatalysts for electrochemical energy conversion. Here, we studied welldefined Pt(100) and Pt(111) electrode surfaces by in situ high-energy surface X-ray diffraction, on-line inductively coupled plasma mass spectrometry, and density functional theory calculations, to elucidate the atomicscale mechanisms of these processes. The locations of the extracted Pt atoms after Pt(100) oxidation reveal distinct differences from the Pt(111) case, which explains the different surface stability. The evolution of a specific stripe oxide structure on Pt(100) produces unstable surface atoms which are prone to dissolution and restructuring, leading to one order of magnitude higher dissolution rates.

show abstract

“…It has been shown that carefully designed Pt NPs would rapidly evolve to thermodynamically equilibrated shapes and sizes with similar activities, regardless the initial shape or size, because of the potential induced dissolution/re-deposition of Pt atoms at potentials close to E onset ORR [32,[52][53][54][55]. Apparently, this process is not modified by the presence of oxygen in the electrolyte [56][57][58], and then, it would be inherent to the nature of the electrolyte and the electrode. Hence, strategies are needed to increase the stability of these NPs, such as the approaches already effectively attempted on metal-Pt alloys [32,53,59,60], and Pt stepped surfaces by modifying the surface by selective deposition of stable adatoms [61], which have increased the stability of these surfaces.…”

Section: A C C E P T E D Mmentioning

confidence: 99%

Oxygen reduction at platinum electrodes: The interplay between surface and surroundings properties

Gómez–Marín

Feliu

2018

Current Opinion in Electrochemistry

View full text Add to dashboard Cite

In this work, recent progress in the understanding of the mechanism of the oxygen reduction reaction at Pt surfaces is shortly reviewed. Specifically, the presence of a soluble and short-lived intermediate different to H 2 O 2 in the ORR reaction path and the interrelated effect between the surface arrangement, adsorption of oxygen-containing species and water structure in the ORR reactivity in acid environments are discussed.Besides, the influence of the proton concentration on the ORR product distribution, the existence of a chemical step and the possible role of the soluble intermediate as a bifurcation point in the mechanism are also analyzed.

show abstract

Pt oxide and oxygen reduction at Pt(111) studied by surface X-ray diffraction

Cited by 18 publications

References 38 publications

The Oxidation of Platinum under Wet Conditions Observed by Electrochemical X-ray Photoelectron Spectroscopy

The Oxidation of Platinum under Wet Conditions Observed by Electrochemical X-ray Photoelectron Spectroscopy

Structure dependency of the atomic-scale mechanisms of platinum electro-oxidation and dissolution

Oxygen reduction at platinum electrodes: The interplay between surface and surroundings properties

Contact Info

Product

Resources

About