Indium phosphate oxalates with layered structures: Solvent-free approach, hydrothermal stability, and proton conduction

Abstract Two new crystalline indium phosphate oxalates (denoted SCU-23 and SCU-25) were synthesized by a solvent-free approach. The two inorganic-organic hybrid solids have different layered structures intercalated with organic cations. Notably, SCU-25 remains stable in boiling water and shows appealing proton conductive behaviors.