Quantifying Site-Specific Proton Dynamics in Phosphate Solid Acids by 1H Double Quantum NMR Spectroscopy

Solid-state magic angle spinning (MAS) NMR was used to investigate changes in proton dynamics in phosphate solid acids that exhibited increased proton conductivity between room temperature and 110 °C. Double quantum dipolar recoupling methods were used to quantify site-specific changes in proton–proton dipolar coupling as a function of temperature. The static dipolar coupling and motionally induced changes to it were compared. This was …