| Autor: |
Metz PC; NYS College of Ceramics, Alfred University, Kazuo Inamori School of Engineering Alfred NY 14802 USA misture@alfred.edu., Ladonis AC; NYS College of Ceramics, Alfred University, Kazuo Inamori School of Engineering Alfred NY 14802 USA misture@alfred.edu., Gao P; NYS College of Ceramics, Alfred University, Kazuo Inamori School of Engineering Alfred NY 14802 USA misture@alfred.edu., Hey T; NYS College of Ceramics, Alfred University, Kazuo Inamori School of Engineering Alfred NY 14802 USA misture@alfred.edu., Misture ST; NYS College of Ceramics, Alfred University, Kazuo Inamori School of Engineering Alfred NY 14802 USA misture@alfred.edu. |
| Jazyk: |
angličtina |
| Zdroj: |
RSC advances [RSC Adv] 2020 Jan 08; Vol. 10 (3), pp. 1484-1497. Date of Electronic Publication: 2020 Jan 08 (Print Publication: 2020). |
| DOI: |
10.1039/c9ra08432k |
| Abstrakt: |
This work reports the layer-tunnel conversion of porous dehydrated synthetic alkali-free δ-MnO 2 analogs prepared by exfoliation, flocculation, and heat treatment of nanosheets derived from highly crystalline potassium birnessite. High surface area porous solids result, with specific surface areas of 90-130 m 2 g -1 and isotherms characteristic of both micro and macropores. The microstructures of the re-assembled floccules are reminiscent of crumpled paper where single and re-stacked nanosheets form the walls of interconnected macropores. The atomic and local structures of the floccules heat treated from 60-400 °C are tracked by Raman spectroscopy and synchrotron X-ray total scattering measurements. During heating, the nanosheets comprising the pore walls condense to form tunnel-structured fragments beginning at temperatures below 100 °C, while the microstructure with high surface area remains intact. The flocc microstructure remains largely unchanged in samples heated up to 400 °C while an increasing fraction of the sample is transformed, at least locally, to possess 1D tunnels characteristic of α-MnO 2 . Cyclic voltammetry in Na 2 SO 4 aqueous electrolyte reflects the nanoscale structural evolution, where intercalative pseudocapacitance diminishes with the degree of transformation. Collectively, these results demonstrate that it is feasible to tailor the materials for applications incorporating nanoporous solids and nanofluidics, and specifically imply strategies to maintain a kinetically accessible interlayer contribute to Na intercalative pseudocapacitance.
Competing Interests: There are no conflicts to declare.
(This journal is © The Royal Society of Chemistry.) |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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