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Yan T, Hou H, Wu C, Cai Y, Yin A, Cao Z, Liu Z, He P, Xu J. Unraveling the molecular mechanism for enhanced gas adsorption in mixed-metal MOFs via solid-state NMR spectroscopy. Proc Natl Acad Sci U S A 2024; 121:e2312959121. [PMID: 38300865 PMCID: PMC10861867 DOI: 10.1073/pnas.2312959121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 12/07/2023] [Indexed: 02/03/2024] Open
Abstract
The incorporation of multiple metal ions in metal-organic frameworks (MOFs) through one-pot synthesis can induce unique properties originating from specific atomic-scale spatial apportionment, but the extraction of this crucial information poses challenges. Herein, nondestructive solid-state NMR spectroscopy was used to discern the atomic-scale metal apportionment in a series of bulk Mg1-xCox-MOF-74 samples via identification and quantification of eight distinct arrangements of Mg/Co ions labeled with a 13C-carboxylate, relative to Co content. Due to the structural characteristics of metal-oxygen chains, the number of metal permutations is infinite for Mg1-xCox-MOF-74, making the resolution of atomic-scale metal apportionment particularly challenging. The results were then employed in density functional theory calculations to unravel the molecular mechanism underlying the macroscopic adsorption properties of several industrially significant gases. It is found that the incorporation of weak adsorption sites (Mg2+ for CO and Co2+ for CO2 adsorption) into the MOF structure counterintuitively boosts the gas adsorption energy on strong sites (Co2+ for CO and Mg2+ for CO2 adsorption). Such effect is significant even for Co2+ remote from Mg2+ in the metal-oxygen chain, resulting in a greater enhancement of CO adsorption across a broad composition range, while the enhancement of CO2 adsorption is restricted to Mg2+ with adjacent Co2+. Dynamic breakthrough measurements unambiguously verified the trend in gas adsorption as a function of metal composition. This research thus illuminates the interplay between atomic-scale structures and macroscopic gas adsorption properties in mixed-metal MOFs and derived materials, paving the way for developing superior functional materials.
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Affiliation(s)
- Tao Yan
- Tianjin Key Lab for Rare Earth Materials and Applications, School of Materials Science and Engineering and National Institute for Advanced Materials, Nankai University, Tianjin300350, People’s Republic of China
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi030001, People’s Republic of China
- National Energy Center for Coal to Clean Fuels, Synfuels China Technology Co., Ltd., Beijing101400, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Huaming Hou
- National Energy Center for Coal to Clean Fuels, Synfuels China Technology Co., Ltd., Beijing101400, People’s Republic of China
| | - Changzong Wu
- Tianjin Key Lab for Rare Earth Materials and Applications, School of Materials Science and Engineering and National Institute for Advanced Materials, Nankai University, Tianjin300350, People’s Republic of China
| | - Yuhang Cai
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi030001, People’s Republic of China
- National Energy Center for Coal to Clean Fuels, Synfuels China Technology Co., Ltd., Beijing101400, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Anping Yin
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi030001, People’s Republic of China
- National Energy Center for Coal to Clean Fuels, Synfuels China Technology Co., Ltd., Beijing101400, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Zhi Cao
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi030001, People’s Republic of China
- National Energy Center for Coal to Clean Fuels, Synfuels China Technology Co., Ltd., Beijing101400, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Zhong Liu
- Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Provincial Key Laboratory of Resources and Chemistry of Salt Lakes, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai810008, People’s Republic of China
| | - Peng He
- State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi030001, People’s Republic of China
- National Energy Center for Coal to Clean Fuels, Synfuels China Technology Co., Ltd., Beijing101400, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Jun Xu
- Tianjin Key Lab for Rare Earth Materials and Applications, School of Materials Science and Engineering and National Institute for Advanced Materials, Nankai University, Tianjin300350, People’s Republic of China
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Abstract
Optical spectromicroscopies, which can reach atomic resolution due to plasmonic enhancement, are perturbed by spontaneous intensity modifications. Here, we study such fluctuations in plasmonic electroluminescence at the single-atom limit profiting from the precision of a low-temperature scanning tunneling microscope. First, we investigate the influence of a controlled single-atom transfer from the tip to the sample on the plasmonic properties of the junction. Next, we form a well-defined atomic contact of several quanta of conductance. In contact, we observe changes of the electroluminescence intensity that can be assigned to spontaneous modifications of electronic conductance, plasmonic excitation, and optical antenna properties all originating from minute atomic rearrangements at or near the contact. Our observations are relevant for the understanding of processes leading to spontaneous intensity variations in plasmon-enhanced atomic-scale spectroscopies such as intensity blinking in picocavities.
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Affiliation(s)
- Anna Rosławska
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
- Université
de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - Pablo Merino
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
- Instituto
de Ciencia de Materiales de Madrid, CSIC, E-28049 Madrid, Spain
- Instituto
de Física Fundamental, CSIC, E-28006 Madrid, Spain
| | - Abhishek Grewal
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
| | | | - Klaus Kuhnke
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
| | - Klaus Kern
- Max-Planck-Institut
für Festkörperforschung, D-70569 Stuttgart, Germany
- Institut
de Physique, École Polytechnique
Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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