Efficient Proton Transport Achieved under Wide Humidity Conditions by Encapsulating Multiple Proton Carriers in MOF

It is essential to investigate proton conductors exhibiting high proton conductivity across diverse environmental conditions in order to mitigate the reliance of conventional electrolytes on water. Herein, a methodology for the encapsulation of an ionic liquid (IL) that has rich proton carriers within sulfonic acid-functionalized MOF-808–2.5SO4 is developed. The resulting IL@MOF-808–2.5SO4 demonstrates high proton conductivities under wide humidity conditions, coupled with good durability in performance. The excellent performance is attributed to the synergistic interactions among environmental water molecules, the sulfonic acid groups present in MOF-808–2.5SO4, and the plentiful proton carriers found with the IL. By addressing this limitation, this study aims to broaden the applicability of the proton conductors.