The mechanism of Li2O2-film formation and reoxidation – Influence of electrode roughness and single crystal surface structure

Koellisch-Mirbach, Andreas; Lohrmann, Tabea; Reinsberg, Philip Heinrich; Baltruschat, Helmut

doi:10.1016/j.jelechem.2020.114560

Cited by 4 publications

(17 citation statements)

References 53 publications

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“…A clear difference is the appearance of the anodic peak close to 0.0 V vs Ag|Ag + for Pt(100). In an earlier publication [48], we found a similar behavior for Pt(100) in Li + -containing DMSO. We have to mention that this feature at 0.0 V vanishes during the second cycle and was not observed by Galloway et al under the same conditions.…”

Section: Resultssupporting

confidence: 77%

“…Thus, we have to conclude that Pt(100) is more slowly blocked compared to Pt(111) and the complete reoxidation of the adsorbed/deposited ORR products requires higher potential. The formation of 2 ML peroxide exclusively on Pt(100) is also observed in Li + -containing DMSO [48]. The number of transferred electrons during the ORR (around −1.2 V) further hints an earlier peroxide formation on Pt(111) compared to Pt(100), which might be the reason for the earlier electrode deactivation for Pt(111).…”

Section: Resultsmentioning

confidence: 67%

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Mixed Lithium and Sodium Ion Aprotic DMSO Electrolytes for Oxygen Reduction on Au and Pt Studied by DEMS and RRDE

et al. 2021

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In order to advance the development of metal-air batteries and solve possible problems, it is necessary to gain a fundamental understanding of the underlying reaction mechanisms. In this study we investigate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER, from species formed during ORR) in Na+ containing dimethyl sulfoxide (DMSO) on poly and single crystalline Pt and Au electrodes. Using a rotating ring disk electrode (RRDE) generator collector setup and additional differential electrochemical mass spectrometry (DEMS), we investigate the ORR mechanism and product distribution. We found that the formation of adsorbed Na2O2, which inhibits further oxygen reduction, is kinetically favored on Pt overadsorption on Au. Peroxide formation occurs to a smaller extent on the single crystal electrodes of Pt than on the polycrystalline surface. Utilizing two different approaches, we were able to calculate the heterogeneous rate constants of the O2/O2− redox couple on Pt and Au and found a higher rate for Pt electrodes compared to Au. We will show that on both electrodes the first electron transfer (formation of superoxide) is the rate-determining step in the reaction mechanism. Small amounts of added Li+ in the electrolyte reduce the reversibility of the O2/O2− redox couples due to faster and more efficient blocking of the electrode by peroxide. Another effect is the positive potential shift of the peroxide formation on both electrodes. The reaction rate of the peroxide formation on the Au electrode increases when increasing the Li+ content in the electrolyte, whereas it remains unaffected on the Pt electrode. However, we can show that the mixed electrolytes promote the activity of peroxide oxidation on the Pt electrode compared to a pure Li+ electrolyte. Overall, we found that the addition of Li+ leads to a Li+-dominated mechanism (ORR onset and product distribution) as soon as the Li+ concentration exceeds the oxygen concentration. Graphical abstract

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Section: Resultssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 67%

Mixed Lithium and Sodium Ion Aprotic DMSO Electrolytes for Oxygen Reduction on Au and Pt Studied by DEMS and RRDE

et al. 2021

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“…The influence of the electrode surface structure was taken into account by using single crystalline electrodes on the one hand and rough electrodes on the other. A similar approach was also used to investigate the ORR/OER in case of Li + containing DMSO in our earlier work [28] . We found that mostly Li 2 O 2 is formed on rough electrodes during the ORR and thus showed once again, that the surface structure strongly affects the electrochemical reactions.…”

Section: Introductionmentioning

confidence: 66%

“…The end of the glass bead was immersed into the working electrolyte, while the open end was immersed into the RE electrolyte. The size of the thin‐layer compartment of the WE and of the compartment of the porous Teflon membrane (serving as the interface to the vacuum) were defined by a Teflon spacer of 200 μm and 100 μm thickness and a diameter of 6 mm (electrode area of 0.283 cm 2 ), as in our previous study [28] . More detailed information about the DEMS setup and the dual thin‐layer cell can be found elsewhere [22,31–34] .…”

Section: Methodsmentioning

confidence: 99%

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Electrochemical Reduction of O₂ in Ca²⁺‐Containing DMSO: Role of Roughness and Single Crystal Structure

et al. 2021

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In this study, the oxygen reduction reaction (ORR) in Ca2+‐containing dimethyl sulfoxide (DMSO) at well‐ordered and rough electrode surfaces is compared by using cyclic voltammetry, differential electrochemical mass spectrometry, rotating ring disk electrode, and atomic force microscopy measurements. Slightly soluble CaO2 is the main product during early ORR on gold electrodes; after completion of a monolayer of CaO and/or CaO2, which is formed in parallel and in competition to the peroxide, only superoxide is formed. When the monolayer is completely closed on smooth annealed Au, no further reduction occurs, whereas on rough Au a defect‐rich layer allows for continuous formation of superoxide. CaO2 formed either via two subsequent 1 normale- transfer steps or by disproportionation of superoxide may be deposited on top of the CaO/CaO2 adsorbate layer. The slow dissolution of the peroxide particles is demonstrated by AFM. Whereas a smooth CaO/CaO2‐covered electrode shows severe deactivation and a CaO/CaO2‐covered rough electrode allows for diffusion‐limited superoxide formation, on single crystals peroxide formation is more pronounced. The reason is most likely the lack of nucleation sites for the blocking CaO/CaO2 layer. RRDE investigations showed sluggish reoxidation kinetics of the dissolved peroxide, which are most likely due to ion pairing with Ca2+. The apparent transfer coefficient is estimated by using variation of the electrode roughness, confirming the result of the usual Tafel analysis and indicating an equilibrated first 1 normale- transfer.

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Towards a Generalized ORR Mechanism in M²⁺‐Containing DMSO: Oxygen Reduction and Evolution in Ca²⁺‐Containing DMSO on Atomically Smooth and Rough Pt

et al. 2022

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The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in Ca 2 + containing dimethyl sulfoxide (DMSO) on atomically smooth Pt(111) and Pt(100) and rough Pt surfaces is reported. As demonstrated by cyclic voltammetry and XPS, the bromine adlayer used to protect Pt single crystals against ambient air and solvent vapor is desorbed in DMSO and does not affect the following measurements. Cyclic voltammetry, differential electrochemical mass spectrometry (DEMS), and rotating ring disk electrode (RRDE) investigations with variation of the electrode surface roughness and atomically surface structure show, that on Pt electrodes the CaO 2 adsorbate layer formation determines the ORR product distribution. On Pt electrodes, calcium peroxide is formed on the clean electrode, whereas calcium superoxide is formed at the adsorbate covered electrode. We furthermore identified four key parameters, which strongly affect the ORR product distribution: 1) The electrode oxide interaction: A strong interaction increases superoxide contribution; 2) The alkaline earth metal oxide interaction: A strong interaction increases peroxide contribution; 3) The electrode surface area: A large electrode surface area increases peroxide contribution; 4) Electrode surface defects: Defects increase superoxide contribution. Finally, reviewing earlier results of our group, we provide a more general mechanism for the oxygen reduction alkaline earth metal cation containing DMSO, for a variety of electrode materials.

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The mechanism of Li2O2-film formation and reoxidation – Influence of electrode roughness and single crystal surface structure

Cited by 4 publications

References 53 publications

Mixed Lithium and Sodium Ion Aprotic DMSO Electrolytes for Oxygen Reduction on Au and Pt Studied by DEMS and RRDE

Mixed Lithium and Sodium Ion Aprotic DMSO Electrolytes for Oxygen Reduction on Au and Pt Studied by DEMS and RRDE

Electrochemical Reduction of O₂ in Ca²⁺‐Containing DMSO: Role of Roughness and Single Crystal Structure

Towards a Generalized ORR Mechanism in M²⁺‐Containing DMSO: Oxygen Reduction and Evolution in Ca²⁺‐Containing DMSO on Atomically Smooth and Rough Pt

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The mechanism of Li2O2-film formation and reoxidation – Influence of electrode roughness and single crystal surface structure

Cited by 4 publications

References 53 publications

Mixed Lithium and Sodium Ion Aprotic DMSO Electrolytes for Oxygen Reduction on Au and Pt Studied by DEMS and RRDE

Mixed Lithium and Sodium Ion Aprotic DMSO Electrolytes for Oxygen Reduction on Au and Pt Studied by DEMS and RRDE

Electrochemical Reduction of O2 in Ca2+‐Containing DMSO: Role of Roughness and Single Crystal Structure

Towards a Generalized ORR Mechanism in M2+‐Containing DMSO: Oxygen Reduction and Evolution in Ca2+‐Containing DMSO on Atomically Smooth and Rough Pt

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Product

Resources

About

Electrochemical Reduction of O₂ in Ca²⁺‐Containing DMSO: Role of Roughness and Single Crystal Structure

Towards a Generalized ORR Mechanism in M²⁺‐Containing DMSO: Oxygen Reduction and Evolution in Ca²⁺‐Containing DMSO on Atomically Smooth and Rough Pt