Reversible Ligand Exchange in Atomically Dispersed Catalysts for Modulating the Activity and Selectivity of the Oxygen Reduction Reaction

Rational control of the coordination environment of atomically dispersed catalysts is pivotal to achieve desirable catalytic reactivity. We report the reversible control of coordination structure in atomically dispersed electrocatalysts via ligand exchange reactions to reversibly modulate their reac...

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Published in:Angewandte Chemie 2021-09, Vol.133 (37), p.20691-20697
Main Authors: Kim, Jae Hyung, Shin, Dongyup, Kim, Jinjong, Lim, June Sung, Paidi, Vinod K., Shin, Tae Joo, Jeong, Hu Young, Lee, Kug‐Seung, Kim, Hyungjun, Joo, Sang Hoon
Format: Article
Language:English
Subjects:
Ammonia
atomically dispersed catalysts
Carbon monoxide
Catalysts
Chemical reduction
Chemistry
Coordination
coordination structure
Dispersion
electrocatalysis
Electrocatalysts
Exchanging
Hydrogen peroxide
Iridium
ligand exchange reaction
Ligands
Oxidation
Oxygen
oxygen reduction reaction
Oxygen reduction reactions
Rhodium
Selectivity
Valence
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Summary:Rational control of the coordination environment of atomically dispersed catalysts is pivotal to achieve desirable catalytic reactivity. We report the reversible control of coordination structure in atomically dispersed electrocatalysts via ligand exchange reactions to reversibly modulate their reactivity for oxygen reduction reaction (ORR). The CO‐ligated atomically dispersed Rh catalyst exhibited ca. 30‐fold higher ORR activity than the NHx‐ligated catalyst, whereas the latter showed three times higher H2O2 selectivity than the former. Post‐treatments of the catalysts with CO or NH3 allowed the reversible exchange of CO and NHx ligands, which reversibly tuned oxidation state of metal centers and their ORR activity and selectivity. DFT calculations revealed that more reduced oxidation state of CO‐ligated Rh site could further stabilize the *OOH intermediate, facilitating the two‐ and four‐electron pathway ORR. The reversible ligand exchange reactions were generalized to Ir‐ and Pt‐based catalysts. Coordination environments of atomically dispersed catalysts are important for their catalytic performances. We report the reversible control of the metal coordination environment in atomically dispersed electrocatalysts via simple ligand exchange reactions, which could reversibly modulate the catalytic reactivity of the oxygen reduction reaction.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.202108439