The oxygen reduction reaction at the three-phase boundary: nanoelectrodes modified with Ag nanoclusters

Clausmeyer, Jan; Botz, Alexander; Öhl, Denis; Schuhmann, Wolfgang

doi:10.1039/c6fd00101g

Cited by 22 publications

(30 citation statements)

References 36 publications

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“…85–87 The electrochemical measurements of single nanoparticles were performed in both immobilization and nanocollision strategies. 88–91 For example, single Pt nanoparticles were electrodeposited on carbon nanoelectrodes to readily study the effect of an ultra-high mass-transfer rate for the reduction of oxygen. 92 As shown in Fig.…”

Section: Applications Of Nanoelectrodesmentioning

confidence: 99%

Advanced electroanalytical chemistry at nanoelectrodes

et al. 2017

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Section: Applications Of Nanoelectrodesmentioning

confidence: 99%

Advanced electroanalytical chemistry at nanoelectrodes

et al. 2017

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“…[12] The ODCs were characterized under industrial workingc onditions by Moussallem et al,w ith varying catalyst particle size distributions, PTFE and silver contents, and porosities. [13] In 2018, Botz et al uncovered information about local activities directly at the electrode surface. [13] In 2018, Botz et al uncovered information about local activities directly at the electrode surface.…”

Section: Introductionmentioning

confidence: 99%

Processes and Their Limitations in Oxygen Depolarized Cathodes: A Dynamic Model‐Based Analysis

2019

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Oxygen depolarized cathodes (ODCs) are key components of alkaline fuel cells and metal–air batteries or of chlor‐alkaline electrolysis, but suffer from limited oxygen availability at the reaction zone. Dynamic analysis is a highly suitable approach to identify the underlying causes, especially the limiting steps and process interactions in such gas diffusion electrodes. Herein, a one‐dimensional, dynamic, three‐phase model for analyzing the oxygen reduction reaction in silver‐based ODCs is presented. It allows for a detailed evaluation of the electrochemical reaction, the mass transport processes, and their interaction. The model also reveals that the depletion of reactant oxygen in the liquid electrolyte is caused by the current‐dependent change of the gas–liquid equilibrium as the limiting subprocess. The phase equilibrium, in turn, depends on the slow mass transport of water and hydroxide ions in the liquid phase. Key parameters are the location or size of the gas–liquid interface within the electrode. Profiles of local concentrations and partial pressures of different species reveal a steep gradient of oxygen in the liquid phase, but no limitation in oxygen mass transport in the gas phase. Dynamic simulations with potential steps allowed the identification of different time constants to separate overlapping processes. Accordingly, the mass transport of water and hydroxide ions was identified as the slowest process that strongly influenced the dynamic response of all species, including oxygen, and of the current. The characteristic time constant of the mass transport of water and hydroxide ions across the liquid phase within the ODC is determined to be τmt,0.166667emnormalH2normalO ≈0.176 s, whereas the time constant of oxygen mass transport into the reaction zone is several magnitudes smaller: τmt,0.166667emnormalO2 ≈1.70×10−6 s. Finally, a sensitivity analysis confirms that the overall performance is best improved by adjusting mass transport properties in the liquid phase.

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“…Another interesting work was done by Clausmeyer and coworkers, who electrodeposited Ag clusters on bi-functional Θ-shaped nanoelectrodes for oxygen reduction. The high current densities observed for the ORR in chlor-alkali electrolyzers can be explained by the local oversaturation of O 2 in the direct vicinity of microscopic gas channels [87].…”

Section: Ag Clusters For Orrmentioning

confidence: 99%

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

Tang

Wang

2018

Catalysts

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Highly-efficient catalysts for the oxygen reduction reaction (ORR) have been extensively investigated for the development of proton exchange membrane fuel cells (PEMFCs). The state-ofthe-art Pt/C catalysts suffer from high price, limited accessibility of Pt, sluggish reaction kinetics, as well as undesirable long-term durability. Engineering ultra-small noble metal clusters with high surface-to-volume ratios and robust stabilities for ORR represents a new avenue. After a simple introduction regarding the significance of ORR and the recent development of noble metal clusters, the general ORR mechanism in both acidic and basic media is firstly discussed. Subsequently, we will summarize the recent efforts employing Pt, Au, Ag, Pd and Ru clusters, as well as the alloyed bi-metallic clusters for acquiring highly efficient catalysts to enhance both the activity and stability of ORR. Molecular noble metal clusters with definitive composition to reveal the relevant ORR mechanism will be particularly highlighted. Finally, the current challenges, the future outlook, as well as the perspectives in this booming field will be proposed, featuring the great opportunities and potentials to engineering noble metal clusters as highly-efficient and durable cathodic catalysts for fuel cell applications.

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The oxygen reduction reaction at the three-phase boundary: nanoelectrodes modified with Ag nanoclusters

Cited by 22 publications

References 36 publications

Advanced electroanalytical chemistry at nanoelectrodes

Advanced electroanalytical chemistry at nanoelectrodes

Processes and Their Limitations in Oxygen Depolarized Cathodes: A Dynamic Model‐Based Analysis

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

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