Integrating molecular design and crystal engineering approaches in non-humidified intermediate-temperature proton conductors based on a Dawson-type polyoxometalate and poly(ethylene glycol) derivatives.
Nanoscale
; 13(17): 8049-8057, 2021 May 07.
Article
en En
| MEDLINE
| ID: mdl-33956921
Anionic metal-oxygen clusters known as polyoxometalates (POMs) have been widely researched as components of proton conductors. While proton conduction under non-humidified intermediate-temperature (100-250 °C) conditions is advantageous from the viewpoint of kinetics, few solid-state materials, not to mention POM-based crystals, show truly effective proton conduction without the aid of water vapor. In this context, non-volatile proton-conductive polymers have been confined into POM-based frameworks, while fast proton conduction was infeasible. Herein, we demonstrate a new strategy to synthesize POM-polymer composites exhibiting fast proton conduction under non-humidified intermediate-temperature conditions. Specifically, a molecular design approach utilizing poly(ethylene glycol)s (PEGs) of different terminal groups or chain lengths controls the proton carrier density, and a crystal engineering approach using a large Dawson-type POM ([α-P2W18O62]6-) with an anisotropic molecular shape and alkali metal ions as counter cations fine-tunes the mobility of the confined PEGs as proton carriers. By integrating these approaches, proton conductivity over 10-4 S cm-1 at 150 °C, comparable to the well-known highly proton-conductive solid-state materials, is achieved. The proton conduction mechanism is discussed with alternative current impedance spectroscopy jointly with specific heat capacity measurements and solid-state NMR spectroscopy.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Nanoscale
Año:
2021
Tipo del documento:
Article
País de afiliación:
Japón
Pais de publicación:
Reino Unido