Nonmetal Organic Frameworks Exhibit High Proton Conductivity

Porous materials, such as metal-organic frameworks (MOFs) and porous organic salts, are promising materials for proton conduction. Recently, we developed a new subclass of porous materials, isoreticular nonmetal organic frameworks (N-MOFs), which can be designed using crystal structure prediction (CSP). Here, two porous, isostructural, and water-stable halide N-MOFs were prepared and found to show good proton conductivity of up to 1.1 × 10^-1 S cm^-1 at 70 °C and 90% relative humidity. Changing the halides in these N-MOF materials affects the resulting proton conductivity, as observed in previous studies involving MOFs and lead halides. Although this is the first study of proton conductivity in N-MOFs, the bromide salt, TTBT.Br, shows a higher conductivity than most polycrystalline MOFs and porous organic salts, approaching that of Nafion.