Abstract The reduction of dioxygen to produce selectively H2O2or H2O is crucial in various fields. While platinum‐based materials excel in 4H+/4e−oxygen reduction reaction (ORR) catalysis, cost and resource limitations drive the search for cost‐effective and abundant transition metal catalysts. It is thus of great importance to understand how the selectivity and efficiency of 3d‐metal ORR catalysts can be tuned. In this context, we report on a Co complex supported by a bisthiolate N2S2‐donor ligand acting as a homogeneous ORR catalyst in acetonitrile solutions both in the presence of a one‐electron reducing agent (selectivity for H2O of 93 % and TOFi=3 000 h−1) and under electrochemically‐assisted conditions (0.81 V <η<1.10 V, selectivity for H2O between 85 % and 95 %). Interestingly, such a predominant 4H+/4e−pathway for Co‐based ORR catalysts is rare, highlighting the key role of the thiolate donor ligand. Besides, the selectivity of this Co catalyst under chemical ORR conditions is inverse with respect to the Mn and Fe catalysts supported by the same ligand, which evidences the impact of the nature of the metal ion on the ORR selectivity.
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Electrocatalytic hydrogen evolution reaction by a Ni(N 2 O 2 ) complex based on 2,2′-bipyridine
In the face of rising atmospheric carbon dioxide (CO 2 ) emissions from fossil fuel combustion, the hydrogen evolution reaction (HER) continues to attract attention as a method for generating a carbon-neutral energy source for use in fuel cells. Since some of the best-known catalysts use precious metals like platinum, which have low natural abundance and high cost, developing efficient Earth abundant transition metal catalysts for HER is an important objective. Building off previous work with transition metal catalysts bearing 2,2′-bipyridine-based ligand frameworks, this work reports the electrochemical analysis of a molecular nickel( ii ) complex, which can act as an electrocatalyst for the HER with a faradaic efficiency for H 2 of 94 ± 8% and turnover frequencies of 103 ± 6 s −1 when pentafluorophenol is used as a proton donor. Computational studies of the Ni catalyst suggest that non-covalent interactions between the proton donor and ligand heteroatoms are relevant to the mechanism for electrocatalytic HER.
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- Award ID(s):
- 2018870
- PAR ID:
- 10459058
- Date Published:
- Journal Name:
- Inorganic Chemistry Frontiers
- Volume:
- 10
- Issue:
- 3
- ISSN:
- 2052-1553
- Page Range / eLocation ID:
- 972 to 978
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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