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Abstract Layered oxide cathode with a Li‐O‐vacancy configuration offers high capacity by leveraging additional oxygen redox reactions. However, it faces severe challenges of sluggish kinetics of oxygen redox reactions and lattice oxygen loss, resulting in slow Li+diffusion and rapid electrochemical degradation. Herein, Ti is introduced as electrochemical inactive element into Li‐O‐vacancy configuration to form Mn/vacancy/Ti arrangement within transition metal layers of layered oxide, achieving a marked increase in average output voltage at high current density compared with Ti‐free counterpart. Not only voltage hysteresis between charge and discharge processes can be significantly reduced, but rate capability can be heightened in Li4/7[□1/7Ti1/7Mn5/7]O2by means of retrained over‐potential and improved Li+diffusivity. Furthermore, theoretical calculations suggest that these improvements stem from Ti substitution, which elongates the Li─O bond and lowers the Li+migration energy barrier. Besides, in situ differential electrochemical mass spectrometry and soft X‐ray absorption spectroscopy reveal the modified Li‐O‐vacancy configuration enables reversible anionic and cationic redox behaviors during cycling. These findings provide a promising strategy for tailoring oxygen redox activity and accelerating Li+diffusion kinetics in layered cathode materials with oxygen redox chemistry.
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A tailored multi-functional catalyst for ultra-efficient styrene production under a cyclic redox scheme
Abstract Styrene is an important commodity chemical that is highly energy and CO2intensive to produce. We report a redox oxidative dehydrogenation (redox-ODH) strategy to efficiently produce styrene. Facilitated by a multifunctional (Ca/Mn)1−xO@KFeO2core-shell redox catalyst which acts as (i) a heterogeneous catalyst, (ii) an oxygen separation agent, and (iii) a selective hydrogen combustion material, redox-ODH auto-thermally converts ethylbenzene to styrene with up to 97% single-pass conversion and >94% selectivity. This represents a 72% yield increase compared to commercial dehydrogenation on a relative basis, leading to 82% energy savings and 79% CO2emission reduction. The redox catalyst is composed of a catalytically active KFeO2shell and a (Ca/Mn)1−xO core for reversible lattice oxygen storage and donation. The lattice oxygen donation from (Ca/Mn)1−xO sacrificially stabilizes Fe3+in the shell to maintain high catalytic activity and coke resistance. From a practical standpoint, the redox catalyst exhibits excellent long-term performance under industrially compatible conditions.
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- Award ID(s):
- 1923468
- PAR ID:
- 10215317
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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