Cooperative proton transportation based on the reversible single crystal–single crystal transformation in a highly water-stable Cu-MOF with its facile and scalable preparation

Abstract

Here, we have reported a highly crystalline Cu-MOF (denoted as HNNU-2) that was synthesized via a one-step method in a flask at close to room temperature. HNNU-2 could not only be prepared on a larger scale, but also exhibited an excellent chemical stability, which maintained its perfect framework even after being bathed in boiling water in a pH range of 5–13 for one week. Based on a reversible single crystal–single crystal transformation, cooperative proton transportation reasonably explains the enormous variation in the proton conductivity from 10⁻⁷ S cm⁻¹ below 75 °C to 10⁻³ S cm⁻¹ above 75 °C.