scholarly journals Effects of Supports BET Surface Areas on Membrane Electrode Assembly Performance at High Current Loads

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 195
Author(s):  
Paritosh Kumar Mohanta ◽  
Masuma Sultana Ripa ◽  
Fabian Regnet ◽  
Ludwig Jörissen
Keyword(s):  
Surface Area ◽  
Catalyst Layer ◽  
Membrane Electrode Assembly ◽  
Bet Surface Area ◽  
Membrane Electrode ◽  
Active Surface Area ◽  
High Current ◽  
Current Load ◽  
Support Materials ◽  
Surface Areas

In this work, we investigated the influence of catalyst supports, particularly Brunauer, Emmett, and Teller (BET) surface area of the catalyst support materials, on membrane electrode assembly (MEA) performance. Keeping the anode catalyst layer (CL), membrane, Pt loading, and operating condition unchanged, we prepared cathode CLs using catalysts of identical Pt content (30 wt% Pt) which were supported on carbon black materials having different BET surface areas. We observed optimum cell voltage at high current load when using cathode catalyst layers prepared from catalysts supported on carbons having medium-BET surface area. High-BET surface area supports, although beneficial at low current density as well as low-BET surface area supports, led to increased voltage losses at high current load due to mass transport limitations which can be explained by the electrochemically active surface area available and water management in the catalyst layer.

Tenacious Mass Transfer Limitations Drive Catalytic Selectivity during Electrochemical Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kailun Yang ◽  
Recep Kas ◽  
Wilson A. Smith
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Catalyst Layer ◽  
Active Surface ◽  
Active Surface Area ◽  
High Concentration ◽  
Copper Electrodes ◽  
Surface Enhanced ◽  
Local Current

<p>This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer. </p> <p> </p>

Boosting Membrane Hydration for High Current Densities in Membrane Electrode Assembly CO2 Electrolysis

2020 ◽  
Vol 12 (49) ◽  
pp. 54585-54595
Author(s):  
Hisan W. Shafaque ◽  
ChungHyuk Lee ◽  
Kieran F. Fahy ◽  
Jason K. Lee ◽  
Jacob M. LaManna ◽  
...  
Keyword(s):  
Membrane Electrode Assembly ◽  
Membrane Electrode ◽  
High Current ◽  
Current Densities ◽  
Co2 Electrolysis

scholarly journals Oxygen Reduction Reaction on Polycrystalline Platinum: On the Activity Enhancing Effect of Polyvinylidene Difluoride

Surfaces ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 69-77
Author(s):  
Alessandro Zana ◽  
Gustav Wiberg ◽  
Matthias Arenz
Keyword(s):  
Mass Transport ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Surface Area ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Rotating Disk Electrode ◽  
Membrane Electrode ◽  
Active Surface Area ◽  
Polyvinylidene Difluoride

There have been several reports concerning the performance improving properties of additives, such as polyvinylidene difluoride (PVDF), to the membrane or electrocatalyst layer of proton exchange membrane fuel cells (PEMFC). However, it is not clear if the observed performance enhancement is due to kinetic, mass transport, or anion blocking effects of the PVDF. In a previous investigation using a thin-film rotating disk electrode (RDE) approach (of decreased complexity as compared to membrane electrode assembly (MEA) tests), a performance increase for the oxygen reduction reaction (ORR) could be confirmed. However, even in RDE measurements, reactant mass transport in the catalyst layer cannot be neglected. Therefore, in the present study, the influence of PVDF is re-examined by coating polycrystalline bulk Pt electrodes by PVDF and measuring ORR activity. The results on polycrystalline bulk Pt indicate that the effects of PVDF on the reaction kinetics and anion adsorption are limited, and that the observed performance increase on high surface area Pt/C most likely is due to an erroneous estimation of the electrochemical active surface area (ECSA) from CO stripping and Hupd.

Self-humidifying membrane electrode assembly with dual cathode catalyst layer structure prepared by introducing polyvinyl alcohol into the inner layer

RSC Advances ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 1333-1338 ◽  
Author(s):  
Huagen Liang ◽  
Ruoyu Xu ◽  
Kaicheng Chen ◽  
Chenyang Shen ◽  
Shibin Yin
Keyword(s):  
Layer Structure ◽  
Catalyst Layer ◽  
Membrane Electrode Assembly ◽  
Membrane Electrode ◽  
Cathode Catalyst ◽  
Constant Voltage ◽  
Short Term ◽  
Cathode Catalyst Layer ◽  
Cathode Structure ◽  
Discharge Test

Short-term constant voltage discharge test of the self-humidifying MEAs with different cathode structure at 60 °C and 30 psi under 20% RH.

Impedance-based Performance Analysis of Micropatterned Polymer Electrolyte Membrane Fuel Cells

2021 ◽  
pp. 1-33
Author(s):  
Morio Tomizawa ◽  
Keisuke Nagato ◽  
Kohei Nagai ◽  
Akihisa Tanaka ◽  
Marcel Heinzmann ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Electrochemical Impedance ◽  
Catalyst Layer ◽  
Membrane Electrode Assembly ◽  
Gas Diffusion ◽  
Reduction Reaction ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Membrane Electrode

Abstract Micropatterns applied to proton exchange membranes can improve the performance of polymer electrolyte fuel cells; however, the mechanism underlying this improvement is yet to be clarified. In this study, a patterned membrane electrode assembly (MEA) was compared with a flat one using electrochemical impedance spectroscopy and distribution of relaxation time analysis. The micropattern positively affects the oxygen reduction reaction by increasing the reaction area. However, simultaneously, the pattern negatively affects the gas diffusion because it lengthens the average oxygen transport path through the catalyst layer. In addition, the patterned MEA is more vulnerable to flooding, but performs better than the flat MEA in low-humidity conditions. Therefore, the composition, geometry, and operating conditions of the micropatterned MEA should be comprehensively optimized to achieve optimal performance.

Ex Situ Characterization Method for Flooding in Gas Diffusion Layers and Membrane Electrode Assemblies With a Hydrophilic Gas Diffusion Layer

2015 ◽  
Vol 12 (6) ◽  
Author(s):  
Toshihiro Tanuma
Keyword(s):  
Catalyst Layer ◽  
Membrane Electrode Assembly ◽  
Gas Diffusion ◽  
Dew Point ◽  
Water Flooding ◽  
Ex Situ ◽  
Membrane Electrode ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
O2 Concentration

Proper water management is required for the operation of polymer electrolyte fuel cells (PEFCs), in order to maintain the critical balance between adequate membrane hydration and prevention of water flooding in the catalyst layer. In PEFCs, the membrane electrode assembly (MEA) is sandwiched between two gas diffusion layers (GDLs). In addition, a microporous layer (MPL) is generally applied to the GDL substrates for better water removal from the cathode catalyst layer. This paper is the first to report on an ex situ characterization method for water flooding in GDLs. As the humidity of O2 gas on the substrate side of the GDL was increased in incremental steps, O2 gas began to diffuse into the MPL side of the GDL. When the O2 relative humidity exceeded the dew point, water flooding was observed on the surface of the MPL and the O2 concentration dropped sharply because the O2 diffusion was suppressed by the produced liquid water. When comparing to the estimated mass transfer loss based on the actual polarization curves of an MEA using the GDL, it was found that the decrease in the O2 concentration on the MPL side of the GDL can be used as an index of water flooding in the PEFC.

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