Hydrogen Motion of CsH2PO4 Electrolyte Using 1H and 31P High-Resolution Nuclear Magnetic Resonance (NMR) Spectroscopy

This study investigated hydrogen-bonded CsH2PO4 (CDP) solid acid using 1H and 31P high-resolution nuclear magnetic resonance (NMR). Below the superprotonic phase transition temperature, the temperature dependence of the 1H NMR spectra was observed with two different hydrogen-bonded networks in the CDP structure. The systematic evolution of the lineshape with temperature dependence indicates hydrogen hopping in the chemical structure of hydrogen-bonded networks in a solid acid lattice. The proton conduction under two types of hydrogen-bonds—interchain and intrachain—in CsH2PO4 in the chemical environments of PO4 tetrahedra is discussed.