A facile and efficient method to improve the proton conductivity of open-framework metal phosphates under aqueous condition

The K+ ions were doped into the inorganic layer of two 2D layer metal phosphates (C2H10N2)[Mn2(PO4)2]·2H2O (1) and (C2H10N2)[Mn2(HPO4)3](H2O) (2), respectively, via ion exchange method. The resultant compounds maintained the original structure of 1 and 2, but significantly improved their proton conductivity, for example, the proton conductivity of 1 increased from 1.14 × 10−5 S.cm−1 to 3.39 × 10−2 S.cm−1 at 99% RH and 293K after doped 0.55 K+ ions; And, it’s remarkably that the proton conductivity of compund 1 with 1.65 K+ ions is the highest among the disclosed open-framework metal phosphates, and has exceed some reported MOFs.