期刊
ADVANCED ENERGY MATERIALS
卷 11, 期 41, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/aenm.202101636
关键词
catalysis; electrochemistry; layered materials; manganese oxides; oxygen evolution reaction; scanning tunneling spectroscopy; water oxidation
类别
资金
- Center for Complex Materials, an Energy Frontier Research Center - US Department of Energy (DOE), Office of Science, Basic Energy Sciences [DE-SC0012575]
The research has discovered a novel water oxidation catalyst with alternating high and low oxidation state layers, showing improved catalytic activity. The preparation of the catalyst is demonstrated for the first time, and it is predicted to facilitate electron transfer.
The discovery of solid-phase, inexpensive transition-metal-based water oxidation catalysts is a central goal for renewable energy, and has led to a general consensus that a partially populated metal e(g) d-electronic state is desirable, leading to favorable catalysis for certain elements in specific oxidation states. In manganese systems, the key species is manganese(III), whose high-spin d(4) electronic configuration places an unpaired electron in the e(g) orbital, which is postulated to contribute to electronic and structural features that support catalysis. Based on density functional theory calculations, it is predicted that electron transfer would be facilitated by a catalyst with alternating low- and high-Mn-III-content sheets, which positions neighboring band edges in closer energetic proximity. The preparation of such catalysts is demonstrated for the first time and it is shown that the catalytic activity is maximized in these systems over more uniform, but more Mn-III-rich systems. The best catalyst possesses alternating high-and low-average oxidation state sheets with interlayer Cs+ ions, and has an overpotential of 450 mV at 10 mA, which represents an improvement of 250 mV over the best unmodified synthetic potassium birnessites. Using scanning tunneling spectroscopy, bandgap modulations consistent with the theoretically predicted band edge shifts are detected.
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