Developing new strategies to fabricate highly efficient proton-conductive materials with defined structures and high proton conductivities is of great significance. We synthesized two novel heteropolytitanium oxo clusters doped with sulfate ions (SO42-) through a simple one-step solvothermal reaction: Ti6O2(OH)2(SO4)4(OiPr)10·2C3H8O (Ti6S4) and Ti16O15(SO4)4(OCH3)26 (Ti16S4). The crystalline materials exhibit superior proton conduction performance. The hydrophilic sulfate ions in the titanium-oxo clusters, along with surrounding water molecules, form continuous proton transport pathways, achieving high proton conductivities for Ti6S4 and Ti16S4. Notably, Ti6S4 and Ti16S4 display ultrahigh proton conductivities of 4.90 × 10-1 and 1.39 × 10-1 S cm-1 at 60 °C and 95% relative humidity (RH), respectively, which are comparable to that of Nafion117 (60 °C, 95% RH). This study offers significant insights for the systematic design of proton conductors and expands the synthesis methodologies of advanced materials.
Long et al. (2026) studied this question.