Electrocatalysis under Conditions of High Mass Transport Rate:  Oxygen Reduction on Single Submicrometer-Sized Pt Particles Supported on Carbon

2004 ◽  
Vol 108 (10) ◽  
pp. 3262-3276 ◽  
Author(s):  
Shengli Chen ◽  
Anthony Kucernak
Keyword(s):  
Mass Transport ◽  
Oxygen Reduction ◽  
Transport Rate ◽  
High Mass ◽  
Mass Transport Rate

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

2016 ◽  
Vol 193 ◽  
pp. 241-250 ◽  
Author(s):  
Jan Clausmeyer ◽  
Alexander Botz ◽  
Denis Öhl ◽  
Wolfgang Schuhmann
Keyword(s):  
Mass Transport ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
Local Delivery ◽  
Model Systems ◽  
Alkaline Media ◽  
High Mass ◽  
Slow Diffusion ◽  
Ag Nanoclusters

Silver nanoclusters are deposited on bifunctional Θ-shaped nanoelectrodes consisting of a carbon nanoelectrode combined with a hollow nanopipette. The Θ-nanoelectrodes are used as model systems to study interfacial mass transport in gas diffusion electrodes and in particular oxygen-depolarized cathodes (ODC) for the oxygen reduction reaction (ORR) in chlor-alkali electrolysers. By local delivery of O2 gas to the electroactive Ag nanoclusters through the adjacent nanopipette, enhanced currents for the ORR at the Ag nanoparticles are recorded which are not accountable when considering the low solubility and slow diffusion of O2 in highly alkaline media. Instead, local oversaturation of O2 leads to current enhancement at the Ag nanoclusters. Due to the intrinsic high mass transport rates at the nanometric electrodes accompanied by local delivery of reactants, the method generally allows to study electrochemical reactions at single nanoparticles beyond the limitations induced by slow diffusion and low reactant concentration. Kinetic and mechanistic information, for instance derived from Tafel slopes, can be obtained from kinetic regimes not accessible to standard techniques.

New methodology for the determination of mass transport rate from rotating disks and/or cylinders in liquid

1994 ◽  
Vol 65 (2) ◽  
pp. 58-64
Author(s):  
Yoshimoto Wanibe ◽  
Esther Boschatzke ◽  
Franz Oeters ◽  
Takashi Itoh
Keyword(s):  
Mass Transport ◽  
Transport Rate ◽  
Rotating Disks ◽  
Mass Transport Rate

Toward Understanding the Utilization of Oxygen Reduction Electrocatalysts under High Mass Transport Conditions and High Overpotentials

ACS Catalysis ◽  
2021 ◽  
pp. 200-211
Author(s):  
Colleen Jackson ◽  
Xiaoqian Lin ◽  
Pieter B. J. Levecque ◽  
Anthony R. J. Kucernak
Keyword(s):  
Mass Transport ◽  
Oxygen Reduction ◽  
High Mass ◽  
High Overpotentials

Enhancement of mass transport and separation of species by oscillatory electroosmotic flows

2006 ◽  
Vol 462 (2071) ◽  
pp. 2017-2038 ◽  
Author(s):  
Hsin-Fu Huang ◽  
Chun-Liang Lai
Keyword(s):  
Mass Transport ◽  
Oscillation Frequency ◽  
Total Mass ◽  
Debye Length ◽  
Transport Rate ◽  
Two Dimensional ◽  
Womersley Number ◽  
Dispersion Effects ◽  
Mass Transport Rate ◽  
Electroosmotic Flows

Mass transport driven by oscillatory electroosmotic flows (EOF) in a two-dimensional micro-channel is studied theoretically. The results indicate that the velocity and concentration distributions across the channel-width become more and more non-uniform as the Womersley number W , or the oscillation frequency, increases. It is also revealed that, with a constant tidal displacement, the total mass transport rate increases with the Womersley number W due to both the stronger convective and the transverse dispersion effects. The total mass transport rate also increases with the tidal displacement (with a fixed oscillation frequency) because of the associated stronger convective effects. The cross-over phenomenon of the mass transport rates for different species becomes possible with sufficiently large Debye lengths and at sufficiently large values of W . Consequently, with proper choices of the Debye length, oscillation frequency and tidal displacement, oscillatory EOF may become a good candidate for the first-step separation of the mass species.

scholarly journals Plume dynamics in Hele-Shaw porous media convection

2016 ◽  
Vol 374 (2078) ◽  
pp. 20150420 ◽  
Author(s):  
Robert E. Ecke ◽  
Scott Backhaus
Keyword(s):  
Porous Media ◽  
Mass Transport ◽  
Molecular Diffusion ◽  
Spatial Separation ◽  
Transport Rate ◽  
Plume Dynamics ◽  
Variable Permeability ◽  
Mass Transport Rate ◽  
Laboratory Analogue ◽  
Hele Shaw Cell

Mass transport in multi-species porous media is through molecular diffusion and plume dynamics. Predicting the rate of mass transport has application in determining the efficiency of the storage and sequestration of carbon dioxide. We study a water and propylene–glycol system enclosed in a Hele-Shaw cell with variable permeability that represents a laboratory analogue of the general properties of porous media convection. The interface between the fluids, tracked using an optical shadowgraph technique, is used to determine the mass transport rate, the spatial separation of solutal plumes, and the velocity and width characteristics of those plumes. One finds that the plume dynamics are closely related to the mass transport rate. This article is part of the themed issue ‘Energy and the subsurface’.

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