Deactivation, reactivation and super-activation of Fe-N/C oxygen reduction electrocatalysts: Gas sorption, physical and electrochemical investigation using NO and O2
| Autor: | Stephan Wagner, Paul Boldrin, Natascha Weidler, Asad Mehmood, Daniel Malko, Stephen Paul, Ulrike I. Kramm, Anthony Kucernak |
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| Přispěvatelé: | Engineering & Physical Science Research Council, Commission of the European Communities, Engineering & Physical Science Research Council (E |
| Rok vydání: | 2021 |
| Předmět: |
Thermal desorption spectroscopy
Inorganic chemistry 0904 Chemical Engineering chemistry.chemical_element 02 engineering and technology 010402 general chemistry Electrochemistry Physical Chemistry 7. Clean energy 01 natural sciences Oxygen Catalysis Adsorption Oxidation state General Environmental Science 0306 Physical Chemistry (incl. Structural) Process Chemistry and Technology Sorption 021001 nanoscience & nanotechnology 0104 chemical sciences 0907 Environmental Engineering chemistry 13. Climate action Electrode 0210 nano-technology |
| Zdroj: | Applied Catalysis B: Environmental |
| ISSN: | 0926-3373 |
| Popis: | We show that gaseous nitric oxide (NO) and oxygen (O2) are useful molecular probes to uncover complex surface processes in Fe-N/C catalysts. We unravel the difference between using gaseous NO in a temperature programmed desorption experiment and using NO (and progenitors) in an electrochemical experiment. Gas phase O2 adsorption is almost exclusively desorbed as CO2, and continued exposure to oxygen increases the amount of chemisorbed oxygen species on the surface. The oxidation state of the carbon surface is an important activity determining factor, and under normal “electrochemical” conditions many of the active sites are blocked. Only by treatment at 600 °C in Ar can we free those sites for oxygen adsorption, however under atmospheric storage, and especially during the oxygen reduction reaction (ORR), the surface quickly becomes deactivated with chemisorbed oxygen species and water. We demonstrate that the material can be super-activated by reductive electrochemical treatment, both in an electrochemical three electrode cell and in a fuel cell. The energy gained following the treatment is significantly larger than the energetic cost. |
| Databáze: | OpenAIRE |
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