Efficiently Boosting Moisture Retention Capacity of Porous Superprotonic Conducting MOF-802 at Ambient Humidity via Forming a Hydrogel Composite Strategy

Metal-organic frameworks (MOFs) provided a versatile platform for the development of new solid protonic electrolytes but faced great challenges regarding their low chemical stability and poor moisture retention capacity. Herein, we presented the proton-conducting study for zirconium-based MOF-802, revealing that MOF-802 possessed excellent features of extra aqueous and acidic stabilities and room-temperature superprotonic conduction with a proton conductivity of 1.05 x 10(-2) S cm(-1) at 288 K under 98% relative humidity (RH). Unfortunately, due to the liberation of water molecules from pores/channels, the proton conductivity of MOF-802 dropped significantly at the temperature above 318 K. To solve this issue, for the first time, MOF-802 was hybridized with poly(vinyl alcohol) (PVA) to form MOF-802@PVA hydrogel composites, where the moisture retention capacity of MOF-802 was greatly improved, giving the high room-temperature proton conductivity over 10(-3) S cm(-1) under ambient humidity. This work paves a new way to improve the moisture retention capacity and proton-conducting performances of porous proton conductors.

Automated summary

The study found that MOF-802 exhibits good proton conductivity at low temperatures and high humidity, but the proton conductivity decreases at higher temperatures due to the release of water molecules. By hybridizing with PVA, the moisture retention capacity of MOF-802 can be improved, thereby enhancing proton conductivity.