Breaking the Scaling Relationship for Oxygen Reduction Reaction Using Molecular Cobalt Complexes

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 13, 2025

Developing catalysts that achieve a higher turnover frequency (TOF) with lower effective overpotential (ηeff) in electrocatalytic reactions is an emerging focus of research. A promising approach to this end modifying the secondary coordination sphere (SCS) can facilitate hydrogen bonding interactions or electrostatic effects, thereby lowering activation energy barrier rate-determining step (rds). Herein, we designed and synthesized series CoIII complexes (1–8) featuring bis-pyridine-dioxime framework, each distinct SCS (−C6H5 (1), o-NHMe2+–C6H4– (2), o-OMe–C6H4– (3), o-OH–C6H4– (4), p-NHMe2+–C6H4– (5), p-OMe–C6H4– (6), pyridine (7), pyrimidine (8)). We investigated their oxygen reduction reaction (ORR) acetonitrile, both CF3COOH 1:1 CF3COOH/CF3COO– buffer solution. All demonstrated selective 4e–/4H+ O2. linear free relationship (LFER) analysis revealed trend increasing TOF ηeff, aligning molecular scaling expectations. However, 2 3 substituents diverged from trend, exhibiting values over 1000 250 times than predicted based on positions log(TOF)/ηeff correlation within Kinetic investigations indicate protonation CoIII(O2•) adduct rds for all catalysts, suggesting functional groups proton transfer, acting as relay sites. propose effect reduces rds, accounting observed deviation LFER. This study underscores critical role designing appropriate enhance catalyst efficiency beyond LFER

Language: Английский

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Selective two-electron and four-electron oxygen reduction reactions using Co-based electrocatalysts

Chemical Society Reviews, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Recent progress made in Co-based electrocatalysts for selective four-electron (4e − ) and two-electron (2e electrocatalytic oxygen reduction reactions is reviewed.

Language: Английский

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The steric hindrance effect of Co porphyrins promoting two-electron oxygen reduction reaction selectivity

Chemical Communications, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 19, 2024

A new Co porphyrin with eight ester groups in ortho and ′ positions of phenyl was designed, which displayed improved 2e oxygen reduction reaction (ORR) selectivity compared a without large steric groups.

Language: Английский

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分子电催化：金属卟啉催化析氢、析氧和氧还原反应研究

Chinese Science Bulletin (Chinese Version), Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 1, 2024

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