Premium
Role of Pyridinic Nitrogen in the Mechanism of the Oxygen Reduction Reaction on Carbon Electrocatalysts
Author(s) -
Takeyasu Kotaro,
Furukawa Moeko,
Shimoyama Yuto,
Singh Santosh K.,
Nakamura Junji
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202014323
Subject(s) - chemistry , catalysis , inorganic chemistry , electrolyte , electrochemistry , carbon fibers , oxygen , pyridinium , carbon black , redox , organic chemistry , electrode , materials science , natural rubber , composite number , composite material
The introduction of pyridinic nitrogen (pyri‐N) into carbon‐based electrocatalysts for the oxygen reduction reaction is considered to create new active sites. Herein, the role of pyri‐N in such catalysts was investigated from a mechanistic viewpoint using carbon black (CB)‐supported pyri‐N‐containing molecules as model catalysts; the highest activity was observed for 1,10‐phenanthroline/CB. X‐ray photoemission spectroscopy showed that in acidic electrolytes, both pyri‐N atoms of 1,10‐phenanthroline could be protonated to form pyridinium ions (pyri‐NH + ). In O 2 ‐saturated electrolytes, one of the pyri‐NH + species was reduced to pyri‐NH upon the application of a potential; no such reduction was observed in N 2 ‐saturated electrolytes. This behavior was ascribed to electrochemical reduction of pyri‐NH + occurring simultaneously with the thermal adsorption of O 2 , as supported by DFT calculations. According to these calculations, the coupled reduction was promoted by hydrophobic environments.