scholarly journals On the limitations in assessing stability of oxygen evolution catalysts using aqueous model electrochemical cells

2020 ◽  
Author(s):  
Julius Knöppel ◽  
Maximilian Möckl ◽  
Daniel Escalera-López ◽  
Kevin Stojanovski ◽  
Markus Bierling ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Inductively Coupled Plasma ◽  
Catalyst Layer ◽  
Operating Conditions ◽  
Model Systems ◽  
Membrane Electrode ◽  
Inductively Coupled ◽  
System A ◽  
Real World Application ◽  
Electrode Assemblies

Abstract Recent research indicates a severe discrepancy between oxygen evolution reaction (OER) catalysts dissolution in aqueous model systems and membrane electrode assemblies (MEA). This questions the relevance of the widespread aqueous testing for real world application. In this study, we aim to determine the processes responsible for the dissolution discrepancy. Experimental parameters known to diverge in both systems are individually tested for their influence on dissolution of an Ir-based catalyst. Ir dissolution is studied in an aqueous model system, a scanning flow cell coupled to an inductively coupled plasma mass spectrometer. Real dissolution rates of the Ir OER catalyst in MEA are measured with a specifically developed, dedicated setup. Overestimated acidity in the anode catalyst layer and stabilization over time in MEAs are identified as main contributors to the dissolution discrepancy. The results shown here lead to clear guidelines for OER electrocatalyst testing parameters to resemble realistic PEMWE operating conditions.

scholarly journals On the limitations in assessing stability of oxygen evolution catalysts using aqueous model electrochemical cells

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Julius Knöppel ◽  
Maximilian Möckl ◽  
Daniel Escalera-López ◽  
Kevin Stojanovski ◽  
Markus Bierling ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Inductively Coupled Plasma ◽  
Catalyst Layer ◽  
Operating Conditions ◽  
Model Systems ◽  
Membrane Electrode ◽  
Inductively Coupled ◽  
System A ◽  
Membrane Electrode Assemblies ◽  
Electrode Assemblies

AbstractRecent research indicates a severe discrepancy between oxygen evolution reaction catalysts dissolution in aqueous model systems and membrane electrode assemblies. This questions the relevance of the widespread aqueous testing for real world application. In this study, we aim to determine the processes responsible for the dissolution discrepancy. Experimental parameters known to diverge in both systems are individually tested for their influence on dissolution of an Ir-based catalyst. Ir dissolution is studied in an aqueous model system, a scanning flow cell coupled to an inductively coupled plasma mass spectrometer. Real dissolution rates of the Ir OER catalyst in membrane electrode assemblies are measured with a specifically developed, dedicated setup. Overestimated acidity in the anode catalyst layer and stabilization over time in real devices are proposed as main contributors to the dissolution discrepancy. The results shown here lead to clear guidelines for anode electrocatalyst testing parameters to resemble realistic electrolyzer operating conditions.

Development of Production Technology for Membrane-Electrode Assemblies With Radical Capturing Layer

2013 ◽  
Vol 10 (1) ◽  
Author(s):  
Toshiro Kobayashi ◽  
Etsuro Hirai ◽  
Hideki Itou ◽  
Takuya Moriga
Keyword(s):  
Production Technology ◽  
Mass Production ◽  
Catalyst Layer ◽  
Gas Diffusion ◽  
Membrane Electrode ◽  
Continuous Formation ◽  
Forming Technology ◽  
Membrane Electrode Assemblies ◽  
Electrode Assemblies ◽  
Opening Ratio

This paper describes the development of mass-production technology for membrane-electrode assemblies (MEA) with a radical capturing layer and verifies its performance. Some of the authors of this paper previously developed an MEA with a radical capturing layer along the boundaries between the electrode catalyst layer and the polymer membrane to realize an endurance time of 20,000 h in accelerated daily start and daily stop (DSS) deterioration tests. Commercialization of these MEAs requires a production technology that suits mass production lines and provides reasonable cost performance. After developing a water-based slurry and selecting a gas diffusion layer (GDL), a catalyst layer forming technology uses a rotary screen method for electrode formation. Studies confirmed continuous formation of the catalyst layer, obtaining an anode/cathode thickness of 55 μm (+10/−20)/50 μm (+10/−20) by optimizing the opening ratio and thickness of the screen plate. A layer-forming technology developed for the radical capturing layer uses a two-fluid spraying method. Continuous formation of an 8 μm thick (±3 μm) radical capturing layer proved feasible by determining the appropriate slurry viscosity, spray head selection, and optimization of spraying conditions.

scholarly journals (M,Ru)O2 (M = Mg, Zn, Cu, Ni, Co) Rutiles and Their Use as Oxygen Evolution Electrocatalysts in Membrane Electrode Assemblies under Acidic Conditions

2020 ◽  
Vol 32 (14) ◽  
pp. 6150-6160
Author(s):  
David L. Burnett ◽  
Enrico Petrucco ◽  
Katie M. Rigg ◽  
Christopher M. Zalitis ◽  
Jamie G. Lok ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Membrane Electrode ◽  
Membrane Electrode Assemblies ◽  
Electrode Assemblies ◽  
Acidic Conditions

THE EFFECT OF OPERATING CONDITIONS ON THE SPARK GENERATED AU-PD NANOPARTICLES

2012 ◽  
Vol 05 ◽  
pp. 291-298 ◽  
Author(s):  
N. S. Tabrizi ◽  
A. Schmidt-Ott
Keyword(s):  
Inductively Coupled Plasma ◽  
Bimetallic Nanoparticles ◽  
Compositional Analysis ◽  
Pd Nanoparticles ◽  
Operating Conditions ◽  
X Ray Diffraction ◽  
Conductive Materials ◽  
Inductively Coupled ◽  
Xrd Patterns ◽  
Spark Energy

Spark discharge is a technique for producing nanoparticles from conductive materials. We had previously used this method to produce Au - Pd bimetallic nanoparticles with a mean diameter of around 6 nm. In this study we changed the operating parameters (e.g. spark energy and frequency, carrier gas type and flow rate) and analyzed the generated particles for their structures and compositions. X ray diffraction (XRD) patterns showed evidence of the formation of alloy phase in all the samples. Compositional analysis by Inductively Coupled Plasma (ICP) revealed that the average mixing ratio was influenced by the polarity, the spark frequency and the gap distance between anode and cathode.

Oxygen Reduction Reaction Causes Iron Leaching from Fe-N-C Electrocatalysts

2021 ◽  
Author(s):  
Yu-Ping Ku ◽  
Konrad Ehelebe ◽  
Markus Bierling ◽  
Florian Speck ◽  
Dominik Seeberger ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Inductively Coupled Plasma ◽  
Catalyst Layer ◽  
Platinum Group Metal ◽  
Gas Diffusion ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Inductively Coupled ◽  
Design And Synthesis

Abstract The electrochemical activity of modern Fe-N-C electrocatalysts in alkaline media is on par with that of platinum. For successful application in fuel cells, however, also high durability and longevity must be demonstrated. Currently, design and synthesis of simultaneously active and stable platinum group metal-free electrocatalysts is hindered by a limited understanding of Fe-N-C degradation, especially under operando conditions. In this work, using a gas diffusion electrode half-cell coupled with inductively coupled plasma mass spectrometry setup, Fe dissolution is studied under more realistic conditions, i.e. real catalyst layer and current densities up to 125 mA·cm-2. Varying the rate of oxygen reduction reaction, we show a remarkable correlation between Faradaic electrode charge and Fe dissolution. This finding is rationalized assuming that oxygen reduction and Fe dissolution reactions are interlinked, likely through a common intermediate formed during the Fe3+/Fe2+ redox transitions in coordinated Fe cations. Moreover, such linear correlation allows an introduction and use of a simple metric (stability number). Hence, in the current work, a powerful tool for a more applied stability screening of different electrocatalysts is introduced, which allows on the one hand fast performance investigations under more realistic conditions, and on the other hand more advanced mechanistic understanding of Fe-N-C degradation in catalyst layers.

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