Testing the Proton Conductivity of Microstructured Titanium-Phosphorus Double Oxide

Stable inorganic substances with high mobile proton content are potentially useful as ion-exchangers and proton conductors. Most of them are used as bulk solids without any morphological features. Recent progress in fine control of micro- and nanostructure, provided materials with developed morphology that exhibited increased functionality. Those include: photoanodes, sensors, catalysts etc. In this work we synthesized a hydrated titanium-phosphorus double oxide (TPDO) with distinct hierarchical structure: microspherical particles consisting of aggregated flakes. Synthesis was based on the use of a stable water-soluble complex of titanium with mandelic acid. Resulting materials showed excellent structural consistency and narrow size distribution. Previously reported titanium phosphates exhibited somewhat mediocre proton conductivity. Massive introduction of dihydrophosphate groups and morphology improvement in the TPDO was hypothesized to improve proton conductivity. Analysis of the conductivity of the as-obtained and calcined samples confirmed the assumption of their different hydration degree. Low conductivity of hierarchically structured Ti-P double oxide and its non-structured analogue showed little effect of the morphology on proton-conducting performance.