In this comprehensive review, recent progress and developments on perfluorinated sulfonic-acid (PFSA) membranes have been summarized on many key topics. Although quite well investigated for decades, PFSA ionomers’ complex behavior, along with their key role in many emerging technologies, have presented significant scientific challenges but also helped create a unique cross-disciplinary research field to overcome such challenges. Research and progress on PFSAs, especially when considered with their applications, are at the forefront of bridging electrochemistry and polymer (physics), which have also opened up development of state-of-the-art in situ characterization techniques as well as multiphysics computation models. Topics reviewed stem from correlating the various physical (e.g., mechanical) and transport properties with morphology and structure across time and length scales. In addition, topics of recent interest such as structure/transport correlations and modeling, composite PFSA membranes, degradat...

New Insights into Perfluorinated Sulfonic-Acid Ionomers

Interaction of nanostructured metal overlayers with oxide surfaces

Electrocatalytic Reduction of Nitrogen: From Haber-Bosch to Ammonia Artificial Leaf

We report the discovery of a highly active Ni−Co alloy electrocatalyst for the oxidation of hydrazine (N2H4) and provide evidence for competing electrochemical (faradaic) and chemical (nonfaradaic) reaction pathways. The electrochemical conversion of hydrazine on catalytic surfaces in fuel cells is of great scientific and technological interest, because it offers multiple redox states, complex reaction pathways, and significantly more favorable energy and power densities compared to hydrogen fuel. Structure−reactivity relations of a Ni60Co40 alloy electrocatalyst are presented with a 6-fold increase in catalytic N2H4 oxidation activity over today’s benchmark catalysts. We further study the mechanistic pathways of the catalytic N2H4 conversion as function of the applied electrode potential using differentially pumped electrochemical mass spectrometry (DEMS). At positive overpotentials, N2H4 is electrooxidized into nitrogen consuming hydroxide ions, which is the fuel cell-relevant faradaic reaction pathway....

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Noble metal-free hydrazine fuel cell catalysts: EPOC effect in competing chemical and electrochemical reaction pathways.

Study of proton exchange membrane fuel cells using electrochemical impedance spectroscopy technique – A review

Rules and Mathematical Modeling of Electrochemical and Chemical Promotion: 1. Reaction Classification and Promotional Rules

The recently established rules of electrochemical promotion of catalysis (EPOC or NEMCA effect) are compared with all combined promotional and kinetic studies published in the Journal of Catalysis and other journals during the last 10 years. In all 33 cases surveyed the promotional rules are found to be in agreement with experiment. These rules enable one to predict the desired type of promoter on the basis of the unpromoted reaction kinetics or the type of kinetics on the basis of the rate dependence on promoter coverage. This validation of the electrochemical promotion rules by the classical promotion literature underlines the functional similarity and only operational difference of electrochemical and classical promotion. It also shows that electrostatic interactions in the double layer formed at the catalyst–gas interface are a key element of promotion in catalysis.

Rules of chemical promotion

The double-layer approach to promotion, electrocatalysis, electrochemical promotion, and metal–support interactions

The effect of membrane thickness on the conductivity of Nafion

Nomenclature. 1. Introduction, Brief History and Basic Concepts. 2. Promotion in Heterogeneous Catalysis. 3. Solid Electrolytes, Catalysis and Spillover. 4. Electrochemical Promotion of Catalytic Reactions. 5. Origin of NEMCA. 6. Rules and Modeling of Promotion. 7. The Absolute Potential. 8. Electrochemical Promotion with O2-Conductors. 9. Electrochemical Promotion with Cationic Conductors. 10. NEMCA with Aqueous Electrolytes and Inorganic Melts. 11. Electrochemical Promotion and Metal-Support Interactions. 12. Practical Applications, Summary and Perspectives. Appendix A: Common Questions about Electrochemical Promotion. Appendix B: Materials and Instrumentation for Starting Electrochemical Promotion Experiments. Appendix C: Main Research Groups. Index.

S. Brosda

Papers

Rules and Mathematical Modeling of Electrochemical and Chemical Promotion: 1. Reaction Classification and Promotional Rules

Rules of chemical promotion

The double-layer approach to promotion, electrocatalysis, electrochemical promotion, and metal–support interactions

The effect of membrane thickness on the conductivity of Nafion

Electrochemical Activation of Catalysis : Promotion, Electrochemical Promotion, and Metal-Support Interactions/ Costas G. Vayenas ...[et al.]