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Abstract Although most class (b) transition metals have been studied in regard to CH4activation, divalent silver (AgII), possibly owing to its reactive nature, is the only class (b) high‐valent transition metal center that is not yet reported to exhibit reactivities towards CH4activation. We now report that electrochemically generated AgIImetalloradical readily functionalizes CH4into methyl bisulfate (CH3OSO3H) at ambient conditions in 98 % H2SO4. Mechanistic investigation experimentally unveils a low activation energy of 13.1 kcal mol−1, a high pseudo‐first‐order rate constant of CH4activation up to 2.8×103 h−1at room temperature and a CH4pressure of 85 psi, and two competing reaction pathways preferable towards CH4activation over solvent oxidation. Reaction kinetic data suggest a Faradaic efficiency exceeding 99 % beyond 180 psi CH4at room temperature for potential chemical production from widely distributed natural gas resources with minimal infrastructure reliance.
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Electrocatalytic Methane Functionalization with d 0 Early Transition Metals Under Ambient Conditions
Abstract The undesirable loss of methane (CH4) at remote locations welcomes approaches that ambiently functionalize CH4on‐site without intense infrastructure investment. Recently, we found that electrochemical oxidation of vanadium(V)‐oxo with bisulfate ligand leads to CH4activation at ambient conditions. The key question is whether such an observation is a one‐off coincidence or a general strategy for electrocatalyst design. Here, a general scheme of electrocatalytic CH4activation with d0early transition metals is established. The pre‐catalysts’ molecular structure, electrocatalytic kinetics, and mechanism were detailed for titanium (IV), vanadium (V), and chromium (VI) species as model systems. After a turnover‐limiting one‐electron electrochemical oxidation, the yielded ligand‐centered cation radicals activate CH4with low activation energy and high selectivity. The reactivities are universal among early transition metals from Period 4 to 6, and the reactivities trend for different early transition metals correlate with their d orbital energies across periodic table. Our results offer new chemical insights towards developing advanced ambient electrocatalysts of natural gas.
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- Award ID(s):
- 1955836
- PAR ID:
- 10302853
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 60
- Issue:
- 51
- ISSN:
- 1433-7851
- Page Range / eLocation ID:
- p. 26630-26638
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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