Abstract
Herein, a room temperature chemical process to synthesize functional, hollow nanostructures from zeolitic imidazolate framework-8 (ZIF-8) and poly(vinylphosphonic acid) (PVPA) is reported. Syntheses are initiated by physically blending the components - a process that is accompanied first by encapsulation of ZIF-8 crystallites by PVPA and then by fragmentation of the crystallites. The fragmentation process is driven by partial displacement of the methyl-imidazolate ligands of Zn(II) in ZIF-8 by phosphonate groups on PVPA. Differences in rates of diffusion for the components of the reactive mixture yield a Kirkendall-like effect that is expressed as a hollow-particle morphology. The obtained hollow nanostructures feature hybrid shells containing PVPA, ZIF-8, and their cross-reacted products. The hybrid structures display substantial proton conductivities that increase with increasing temperature, even under the anhydrous conditions prevailing at temperatures above the boiling point of water. For example, at T = 413 K the proton conductivity of ZIF-8@PVPA reaches 3.2 (±0.12) × 10-3 S cm-1, a value comparatively higher than that for PVPA (or ZIF-8) in isolation. The high value may reflect the availability in the hybrid structures of free (and partially free), amphoteric imidazole species, and their hydrogen-bonding interactions with phosphonate and/or phosphonic acid units. The persistence of ample conductivity at high temperature reflects the elimination of phosphonic acid group dehydration and dimerization - an effect that strikingly degrades the conductivity of pure PVPA under anhydrous conditions.
| Original language | English |
|---|---|
| Pages (from-to) | 23015-23021 |
| Number of pages | 7 |
| Journal | ACS Applied Materials and Interfaces |
| Volume | 8 |
| Issue number | 35 |
| DOIs | |
| Publication status | Published - Sep 7 2016 |
Fingerprint
Keywords
- fuel cell
- hollow nanostructures
- proton conductivity
- PVPA
- ZIF-8
ASJC Scopus subject areas
- Materials Science(all)
Cite this
Proton conducting self-assembled metal-organic framework/polyelectrolyte hollow hybrid nanostructures. / Sen, Unal; Erkartal, Mustafa; Kung, Chung Wei; Ramani, Vijay; Hupp, Joseph T; Farha, Omar K.
In: ACS Applied Materials and Interfaces, Vol. 8, No. 35, 07.09.2016, p. 23015-23021.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Proton conducting self-assembled metal-organic framework/polyelectrolyte hollow hybrid nanostructures
AU - Sen, Unal
AU - Erkartal, Mustafa
AU - Kung, Chung Wei
AU - Ramani, Vijay
AU - Hupp, Joseph T
AU - Farha, Omar K.
PY - 2016/9/7
Y1 - 2016/9/7
N2 - Herein, a room temperature chemical process to synthesize functional, hollow nanostructures from zeolitic imidazolate framework-8 (ZIF-8) and poly(vinylphosphonic acid) (PVPA) is reported. Syntheses are initiated by physically blending the components - a process that is accompanied first by encapsulation of ZIF-8 crystallites by PVPA and then by fragmentation of the crystallites. The fragmentation process is driven by partial displacement of the methyl-imidazolate ligands of Zn(II) in ZIF-8 by phosphonate groups on PVPA. Differences in rates of diffusion for the components of the reactive mixture yield a Kirkendall-like effect that is expressed as a hollow-particle morphology. The obtained hollow nanostructures feature hybrid shells containing PVPA, ZIF-8, and their cross-reacted products. The hybrid structures display substantial proton conductivities that increase with increasing temperature, even under the anhydrous conditions prevailing at temperatures above the boiling point of water. For example, at T = 413 K the proton conductivity of ZIF-8@PVPA reaches 3.2 (±0.12) × 10-3 S cm-1, a value comparatively higher than that for PVPA (or ZIF-8) in isolation. The high value may reflect the availability in the hybrid structures of free (and partially free), amphoteric imidazole species, and their hydrogen-bonding interactions with phosphonate and/or phosphonic acid units. The persistence of ample conductivity at high temperature reflects the elimination of phosphonic acid group dehydration and dimerization - an effect that strikingly degrades the conductivity of pure PVPA under anhydrous conditions.
AB - Herein, a room temperature chemical process to synthesize functional, hollow nanostructures from zeolitic imidazolate framework-8 (ZIF-8) and poly(vinylphosphonic acid) (PVPA) is reported. Syntheses are initiated by physically blending the components - a process that is accompanied first by encapsulation of ZIF-8 crystallites by PVPA and then by fragmentation of the crystallites. The fragmentation process is driven by partial displacement of the methyl-imidazolate ligands of Zn(II) in ZIF-8 by phosphonate groups on PVPA. Differences in rates of diffusion for the components of the reactive mixture yield a Kirkendall-like effect that is expressed as a hollow-particle morphology. The obtained hollow nanostructures feature hybrid shells containing PVPA, ZIF-8, and their cross-reacted products. The hybrid structures display substantial proton conductivities that increase with increasing temperature, even under the anhydrous conditions prevailing at temperatures above the boiling point of water. For example, at T = 413 K the proton conductivity of ZIF-8@PVPA reaches 3.2 (±0.12) × 10-3 S cm-1, a value comparatively higher than that for PVPA (or ZIF-8) in isolation. The high value may reflect the availability in the hybrid structures of free (and partially free), amphoteric imidazole species, and their hydrogen-bonding interactions with phosphonate and/or phosphonic acid units. The persistence of ample conductivity at high temperature reflects the elimination of phosphonic acid group dehydration and dimerization - an effect that strikingly degrades the conductivity of pure PVPA under anhydrous conditions.
KW - fuel cell
KW - hollow nanostructures
KW - proton conductivity
KW - PVPA
KW - ZIF-8
UR - http://www.scopus.com/inward/record.url?scp=84986597980&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84986597980&partnerID=8YFLogxK
U2 - 10.1021/acsami.6b05901
DO - 10.1021/acsami.6b05901
M3 - Article
VL - 8
SP - 23015
EP - 23021
JO - ACS applied materials & interfaces
JF - ACS applied materials & interfaces
SN - 1944-8244
IS - 35
ER -