Role of Pyrophosphate Source for Improving Proton Conductivity and Stability of Sodium Dihydrogen Phosphate

Solid acid composites of (1 – x)NaH₂PO₄/xCeP₂O₇ (x = 0.1–0.4) with different molar weight ratio of NaH₂PO₄ (SDP) and CeP₂O₇ were synthesized and characterized. The characterization of solid acid composites was carried out to determine the structures, thermal stability, and conductivity, utilizing X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and conductivity measurements. The electrolyte pellets of composite powder were prepared for the determination of ionic conductivity. The presence of CeP₂O₇ in the composite had a large impact on the conductivity measurements and increased the ionic conductivity of NaH₂PO₄. The thermal stability of the solid acid composites for dehydration, melting, and decomposition was investigated in the temperature range of 50 to 500°C under open atmospheric environments.