Kinetically induced irreversibility in electro-oxidation and reduction of Pt surface

Jinnouchi, Ryosuke; Kodama, Kensaku; Suzuki, Tomomichi; Morimoto, Yu

doi:10.1063/1.4920974

Cited by 22 publications

(11 citation statements)

References 91 publications

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“…1.0 V, making such an explanation less likely. A second important comment about reaction 4 concerns its bimolecular character, which has recently been postulated by both Gomez-Marin and Feliu 7 and by Jinnouchi et al 52 to be at the origin of the irreversibility of the anodic peak at 1.05 V. They suggested the following reaction:…”

Section: Resultsmentioning

confidence: 95%

Intermediate stages of electrochemical oxidation of single-crystalline platinum revealed by in situ Raman spectroscopy

2016

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Understanding the atomistic details of how platinum surfaces are oxidized under electrochemical conditions is of importance for many electrochemical devices such as fuel cells and electrolysers. Here we use in situ shell-isolated nanoparticle-enhanced Raman spectroscopy to identify the intermediate stages of the electrochemical oxidation of Pt(111) and Pt(100) single crystals in perchloric acid. Density functional theory calculations were carried out to assist in assigning the experimental Raman bands by simulating the vibrational frequencies of possible intermediates and products. The perchlorate anion is suggested to interact with hydroxyl phase formed on the surface. Peroxo-like and superoxo-like two-dimensional (2D) surface oxides and amorphous 3D α-PtO2 are sequentially formed during the anodic polarization. Our measurements elucidate the process of the electrochemical oxidation of platinum single crystals by providing evidence for the structure-sensitive formation of a 2D platinum-(su)peroxide phase. These results may contribute towards a fundamental understanding of the mechanism of degradation of platinum electrocatalysts.

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Section: Resultsmentioning

confidence: 95%

Intermediate stages of electrochemical oxidation of single-crystalline platinum revealed by in situ Raman spectroscopy

2016

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“…Recently, Jinnouchi et al revealed that the generation/ reduction of Pt−O ad causes hysteresis at relatively lower potentials where the subsurface Pt oxides are not formed (<1.1 V). 57 Interestingly, the decrease in ORR activity in the cathodic scan was mitigated by melamine decoration. The potential difference between the anodic and the cathodic LSVs at a current density of 3 mA cm −2 was decreased to 49 mV for a catalyst decorated with melamine after HAP, while the differences were 60 and 57 mV for the as-synthesized catalyst and the catalyst after HAP, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Because a high limit potential was set at 1.2 V in the LSV measurements, the anodic and cathodic scans showed large hysteresis because of Pt oxide formation at 1.2 V and ORR activity was significantly decreased in the cathodic scan. This hysteresis cannot be explained solely in terms of Pt–OH ad formation and further oxidized species such as Pt–O ad or subsurface Pt oxides should be taken into consideration. Recently, Jinnouchi et al revealed that the generation/reduction of Pt–O ad causes hysteresis at relatively lower potentials where the subsurface Pt oxides are not formed (<1.1 V) .…”

Section: Results and Discussionmentioning

confidence: 99%

Creation of a Highly Active Pt/Pd/C Core–Shell-Structured Catalyst by Synergistic Combination of Intrinsically High Activity and Surface Decoration with Melamine or Tetra-(tert-butyl)-tetraazaporphyrin

et al. 2020

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A Pt/Pd/C core−shell-structured catalyst with an extraordinarily high activity of 3625 A g −1 -Pt at 0.9 V versus a reversible hydrogen electrode (RHE) for the oxygen reduction reaction (ORR) was created by a synergistic combination of intrinsically high activity and surface decoration with melamine or tetra-(tert-butyl)-tetraazaporphyrin (tBuTAP). The intrinsically highly active Pt/Pd/C catalyst with an ORR mass activity of ca. 1000 A g −1 -Pt at 0.9 V versus RHE was synthesized by a direct displacement reaction method, and the activity was activated to ca. 1500 A g −1 -Pt via a high activation protocol (HAP) (a rectangular potential cycling of 0.05−1.0 V vs an RHE conducted in 0.1 mol dm −3 HClO 4 under an Ar atmosphere at 80 °C). The ORR activities of the Pt/Pd/C catalysts were further increased by surface decoration with melamine or tBuTAP, and the mass activity of ORR of the catalyst activated by an HAP was enhanced to 3625 A g −1 -Pt at 0.9 V versus RHE via the melamine decoration, which is about 11-fold that of a reference Pt/C catalyst (320 A g −1 -Pt). Cyclic voltammograms, linear sweep voltammograms, and CO stripping voltammograms indicated that the surface decoration further destabilized the OH species (OH ad ) adsorbed on the Pt shell and suppressed the formation of oxide on the Pt shell, which could explain the extraordinary enhancement of ORR activity. We present guidelines for creating Pt-based catalysts with extraordinarily high activity for the ORR by the synergistic combination of the intrinsically active Pt-based catalyst [improvement from the inside of Pt nanoparticles (NPs)] and surface decoration (improvement from the outside of Pt NPs).

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“…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.…”

Section: Introductionmentioning

confidence: 99%

“…[25,26] At above 0.55 V vs. RHE, the CV features of water oxidation become very complicated and draw intensive attention. [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. With more experimental evidence obtained from in situ Raman and STM, in the present study, we accordingly proposed a series of sequential kinetic reactions with potential cycling.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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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.

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Kinetically induced irreversibility in electro-oxidation and reduction of Pt surface

Cited by 22 publications

References 91 publications

Intermediate stages of electrochemical oxidation of single-crystalline platinum revealed by in situ Raman spectroscopy

Intermediate stages of electrochemical oxidation of single-crystalline platinum revealed by in situ Raman spectroscopy

Creation of a Highly Active Pt/Pd/C Core–Shell-Structured Catalyst by Synergistic Combination of Intrinsically High Activity and Surface Decoration with Melamine or Tetra-(tert-butyl)-tetraazaporphyrin

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

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