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Palladium Single‐Atom Catalysts Supported on C@C 3 N 4 for Electrochemical Reactions
Author(s) -
Kim HeeEun,
Lee In Hyuk,
Cho Jinwon,
Shin Sangyong,
Ham Hyung Chul,
Kim Jin Young,
Lee Hyunjoo
Publication year - 2019
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201900772
Subject(s) - catalysis , palladium , scanning transmission electron microscopy , chemistry , selectivity , formic acid , electrochemistry , extended x ray absorption fine structure , noble metal , electrocatalyst , metal , adsorption , crystallography , inorganic chemistry , transmission electron microscopy , absorption spectroscopy , materials science , nanotechnology , electrode , organic chemistry , physics , quantum mechanics
Single atom catalysts (SACs) maximize the utilization of noble metal whereas nanoparticle catalysts have inner metal atoms unavailable. In this study, various electrocatalytic reactions were investigated for Pd and Pt SACs. The single atoms were immobilized on thin layers of graphitic carbon nitride with carbon black (for simplicity, C@C 3 N 4 ) to produce an electrochemically efficient and stable SACs. Single atomic structure was confirmed by high‐angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) and extended X‐ray absorption fine structure (EXAFS) analyses. Oxygen reduction reaction (ORR) and CO stripping experiments were conducted, and the results were compared with the corresponding nanoparticle catalysts. Lack of ensemble sites in the SACs resulted in two‐electron pathway for ORR; single atomic Pd on C@C 3 N 4 (C@C 3 N 4 −Pd 1 ) showed high activity and selectivity for H 2 O 2 formation. DFT calculations showed that C@C 3 N 4 −Pd 1 follows a downhill path for H 2 O 2 formation unlike single atomic Pt on C@C 3 N 4 (C@C 3 N 4 ‐Pt 1 ), resulting in enhanced H 2 O 2 selectivity. Weaker adsorption of oxygen intermediates on C@C 3 N 4 −Pd 1 resulted in enhanced ORR activity. The SACs showed no interaction with CO as confirmed by no CO stripping peak. This resulted in no activity for formic acid oxidation following indirect pathway or methanol oxidation, which necessitates CO ads as reaction intermediates. SACs can be efficient electrocatalysts with high activity and unique selectivity.