Site-Specific Proton Dynamics in Indium-Doped Tin Pyrophosphate

Tin pyrophosphates are solid-state materials that have been proposed for use as proton conductors in intermediate-temperature fuel cells. However, protons must be added synthetically as these materials do not contain structural protons. Protonation via indium doping results in two NMR-resolvable proton signals that correspond to hydrogen-bonded interstitial protons at phosphate tetrahedral and metal octahedral sites. These sites were assigned …