Non-PGM Electrocatalysts for PEM Fuel Cells: Thermodynamic Stability of Potential ORR CoNx-C Electrocatalytic Sites
| Autor: | Vassili Glibin, Gaixia Zhang, Shuhui Sun, Jean-Pol Dodelet |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Renewable Energy Sustainability and the Environment Proton exchange membrane fuel cell 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Electrocatalyst 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Chemical engineering Materials Chemistry Electrochemistry Chemical stability 0210 nano-technology |
| Zdroj: | Journal of The Electrochemical Society. 168:094502 |
| ISSN: | 1945-7111 0013-4651 |
| DOI: | 10.1149/1945-7111/ac1d03 |
| Popis: | We present here a thermodynamic assessment of the stability behavior in acidic environments at 298 and 353 K (80 °C) of several Co-based sites that may potentially be active for the oxygen reduction reaction (ORR) at the cathode of proton exchange membrane (PEM) fuel cells. These sites are: i) the porphyrin-like CoN4/C site located in a micropore, ii) two different 1,10-phenanthroline-like CoN(2+2)/C sites located either in a micropore or embedded into a graphene sheet, and iii) the CoN(4+2)/C site having (at its center) the structural motif of the hexa-aza-macrocyclic complex of Co(II) embedded into a graphene sheet. The calculations of the equilibrium constants ( K c ) for the reactions of demetallation indicate that all evaluated active sites are chemically stable in an acidic medium at both 298 and 353 K. At 298 K, K c values for CoN4/C and for the two examples of CoN(2+2)/C sites are very similar. The same conclusion is also true at 353 K. However, the simple introduction of two supplementary nitrogen atoms in the structure of the embedded hexa-aza CoN(4+2)/C site vs that of the embedded phenanthroline-like CoN(2+2)/C site significantly affects its stability toward Co2+ demetallation, rendering CoN(4+2)/C much less likely to demetallate than CoN(2+2)/C either at 298 or 353 K. |
| Databáze: | OpenAIRE |
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