Synthesis of a Ternary Thiostannate with 3D Channel Decorated by Hydronium for High Proton Conductivity

Metal
chalcogenides with various channel structures feature a number of
interesting properties including fast-ion conductivity and selective
ion exchange. Most of these compounds are popularly prepared based
on the templates of organic amines that play the part of a structure
directing agent and even structure-building units, while it still
remains a challenge as to the organotemplate-free synthesis for these
compounds. Here, a new ternary thiostannate (H3O)4­Cu8Sn3­S12 was synthesized
through a facile, efficient, and organotemplate-free route under hydrothermal
conditions. The framework of (H3O)4­Cu8Sn3­S12 consists of [Cu8Sn6­S24]8– building
units and possesses a 3D interconnected 8-ring channel structure decorated
by pure hydroniums, which not only balance the charges but also facilitate
the proton conductivity. The proton conductivity reaches as high as
1.03 × 10–3 S cm–1 at 393
K under anhydrous conditions, which is 2 orders of magnitude higher
than that of (H3O)2­(enH2)­Cu8Sn3­S12, a similar channel structure
compound prepared by using ethylene­diamine as an organic template.