Tuning proton conduction by different particle sizes in open-framework metal phosphates

Abstract The proton conductions of open-framework metal phosphates K2[(VO)2(HPO4)2(C2O4)] (KVPC) with large and small particle sizes, namely KVPC-L and KVPC-S, have been evaluated. Varied particle sizes result in different proton conductive behaviors. KVPC-S exhibits a high proton conductivity of 1.15 × 10−2 S cm−1 under 40 °C, 95% RH and possesses a stable proton conduction for 4 hours. Furthermore, proton conductivities of composite membranes are investigated, and the value can reach up to 1.19× 10-3 S cm−1 under 60 °C, 95% RH and remain no significant change within 6 hours.