Proton Conduction in Sulfonated Organic-Inorganic Hybrid Monoliths with Hierarchical Pore Structure.
Porous organic-inorganic hybrid monoliths with hierarchical porosity exhibiting macro- and mesopores are prepared via sol-gel process under variation of the mesopore size. Organic moieties in the pore walls are incorporated by substituting up to 10% of the silicon precursor tetramethylorthosilicate with bisilylated benzene molecules. After functionalization with sulfonic acid groups, the resulting sulfonated hybrid monoliths featuring a bimodal pore structure are investigated regarding proton conduction depending on temperature and relative humidity. The hierarchical pore system and controlled mesopore design turn out to be crucial for sulfonation and proton conduction. These sulfonated hybrid hierarchical monoliths containing only 10% organic precursor exhibit higher proton conduction at different relative humidities than sulfonated periodic mesoporous organosilica made of 100% bisilylated precursors exhibiting solely mesopores, even with a lower concentration of sulfonic acid groups.
Institute of Physical Chemistry, Justus-Liebig-University Giessen , 35392 Giessen, Germany.
Martin
M
von der Lehr
Institute of Chemistry, Carl von Ossietzky University Oldenburg , 26129 Oldenburg, Germany.
Christopher F
CF
Seidler
Institute of Chemistry, Carl von Ossietzky University Oldenburg , 26129 Oldenburg, Germany.
Dereje H
DH
Taffa
Institute of Chemistry, Carl von Ossietzky University Oldenburg , 26129 Oldenburg, Germany.
Michael
M
Wark
Institute of Physical Chemistry, Justus-Liebig-University Giessen , 35392 Giessen, Germany.
Bernd M
BM
Smarsly
Institute of Physical Chemistry, Justus-Liebig-University Giessen , 35392 Giessen, Germany.
Roland
R
Marschall
functionalization; mesoporosity; proton conduction; silica; surface modification