Three-Dimensional Protonic Conductivity in Porous Organic Cage Solids

Published

September 13, 2016

Author(s)

Ming Liu, Linjiang Chen, Scott Lewis, Samantha Y. Chong, Marc A. Little, Tom Hasell, Iain M. Aldous, Craig Brown, Martin W. Smith, Carole A. Morrison, Laurence J. Hardwick, Andrew I. Cooper

Abstract

Proton conduction is a fundamental process in biology and in devices such as proton exchange membrane fuel cells. To maximize proton conduction, 3-D conduction pathways are preferred over 1-D pathways, which prevent proton conduction in two-dimensions. Many crystalline porous solids o date show 1-D proton conduction. Here we report porous molecular cages with proton conductivities (up to 10^-3^ S cm^-1 at high relative humidity) that compete with extended metal-organic frameworks. The structure of the organic cage imposes a proton conduction pathway that is necessarily 3-D. The cage molecules also promote proton transfer by confining the water molecules while being sufficiently flexibly to allow hydrogen bond reorganization. The proton conduction is explained at the molecular level through a combination of proton conductivity measurements, crystallography, molecular simulations, and quasi-elastic neutron scattering. These results provide a starting point for high-temperature, anhydrous proton conductors through inclusion of guests other than water in the cage pores.

Citation

Nature Communications

Volume

7

Pub Type

Journals

Download Paper

Local Download

Keywords

quasielastic neutron scattering, porous cages, diffusion, water

Citation

Liu, M. , Chen, L. , Lewis, S. , Chong, S. , Little, M. , Hasell, T. , Aldous, I. , Brown, C. , Smith, M. , Morrison, C. , Hardwick, L. and Cooper, A. (2016), Three-Dimensional Protonic Conductivity in Porous Organic Cage Solids, Nature Communications, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=921121 (Accessed October 14, 2025)