Journal article
Electrochemical probing into the active sites of graphitic-layer encapsulated iron oxygen reduction reaction electrocatalysts
The graphitic-layer encapsulated iron-containing nanoparticles (G@Fe) have been proposed as a potential type of active and stable non-precious metal electrocatalysts (NPMCs) for the oxygen reduction reaction (ORR). However, the contribution of the encapsulated components to the ORR activity is still unclear compared with the well-recognized surface coordinated FeNx/C structure.
Using the strong complexing effect of the iron component with anions, cyanide (CN−) in alkaline and thiocyanate (SCN−) in acidic media, the metal containing active sites are electrochemically probed. Three representative catalysts are chosen for a comparison including the as-prepared encapsulated G@Fe, commercial Fe/N/C catalyst with iron–nitrogen coordinated surface functionalities and molecular iron phthalocyanine (FePc) containing well-defined structures and compositions.
It was found that all samples showed significant shifts of half-wave potentials indicating that surface Fe coordinated sites in all cases. The G@Fe catalyst showed the weakest poisoning effect (the lowest shifts of half-wave potential) compared to the Fe/N/C and FePc catalysts in both electrolytes. These results could be explained that the encapsulated iron components influence the FeNx/C and/or NxC surface functionality.
Language: | English |
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Year: | 2018 |
Pages: | 24-30 |
ISSN: | 20959273 and 20959281 |
Types: | Journal article |
DOI: | 10.1016/j.scib.2017.11.017 |
ORCIDs: | Zhong, Lijie , Jensen, Jens Oluf , Cleemann, Lars Nilausen and Li, Qingfeng |