Integrated Process for Structuring and Functionalizing Ordered Mesoporous Silica to Achieve Superprotonic Conductivity

Abstract

Polyacid-functionalized inorganic mesoporous materials have attracted considerable interest as catalysts, permselective molecular sieves, or drug carriers. Despite the great interest, their synthesis into ordered mesostructures incorporating polyacids densely and homogeneously distributed in the mesopores is a challenge. Moreover, their properties as conductors for energy applications remain completely unexplored. Here, we report an efficient, one-shot environmentally friendly synthesis route to prepare ordered mesoporous silica functionalized with strong polyacids, which exhibits excellent proton conductivity. We used polyion electrostatic complex micelles as structure-directing, functionalizing, and pore-generating agents to obtain a material of remarkable textural and functional quality. It presents large and ordered mesopores hosting monodisperse polyacid chains corresponding to a dense and homogeneous functionalization of 1.2 mmolSO3H gSiO2–1 and a function density of 1 SO3H per nm3 of mesopore volume. Overcoming the performance-limiting inhomogeneities, we designed a superprotonic conductor, while the high value of the conductivity, 0.024 S cm–1 at 363 K/95% relative humidity, was maintained for at least 7 days.