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Seemingly Negligible Amounts of Platinum Nanoparticles Mislead Electrochemical Oxygen Reduction Reaction Pathway on Platinum Single‐Atom Catalysts
Author(s) -
Shin Sangyong,
Kim HeeEun,
Kim BeomSik,
Jeon Sun Seo,
Jeong Hojin,
Lee Hyunjoo
Publication year - 2020
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.202000926
Subject(s) - catalysis , platinum , scanning transmission electron microscopy , platinum nanoparticles , nanoparticle , transmission electron microscopy , atom (system on chip) , electrochemistry , chemistry , dark field microscopy , scanning electron microscope , oxygen reduction reaction , crystallography , materials science , inorganic chemistry , nanotechnology , electrode , microscopy , organic chemistry , physics , computer science , embedded system , optics , composite material
A few studies have claimed that Pt single‐atom catalysts (SACs) can catalyze the oxygen reduction reaction (ORR) following a four‐electron pathway (O 2 +4H + +4e − →2H 2 O). Here, we show that, in the presence of a seemingly negligible amount of Pt nanoparticles, the ORR can mistakenly be thought to occur via a four‐electron pathway on Pt SACs. Various weight percentages (1, 2, 4, 8 wt%) of Pt SACs were prepared on C 3 N 4 layers deposited on a carbon support (C@C 3 N 4 ). Through a combination of H 2 /CO uptakes and high angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) results, the amount of Pt nanoparticles could be estimated when they were mixed with Pt single atoms. Particularly, most of Pt in the 4 wt% Pt catalyst existed as single atoms, but a small number of Pt nanoparticles co‐existed. Although this catalyst seemed to follow the four‐electron pathway, the reaction actually occurred on Pt nanoparticles, not Pt single‐atoms.