Proton Conductivity of Naphthalene Sulfonate Formaldehyde Resin-Doped Mesoporous Niobium and Tantalum Oxide Composites

Proton conductivity in a series of mesoporous niobium and tantalum metal oxide (mX(2)O(5)) composites of naphthalene sulfonic acid formaldehyde resin (NSF) that are resistant to moisture loss at temperatures greater than 50 degrees C is reported. The investigation focuses on the effect to proton conductivity by changing pore size and metal in the mesostructure of the mX(2)O(5) system and thus, a series of mX(2)O(5)-NSF composites were synthesized with C-6, C-12, and C-18 templates. These were characterized by XRD, thermogravimetric analysis, nitrogen ad-sorption, and scanning TEM and then studied using impedance spectroscopy to establish proton conductivity values at various temperatures ranging from 25 to 150 degrees C. The most promising sample displayed a conductivity of 21.96 mScm(-1) at 100 degrees C, surpassing the literature value for Nafion 117 (ca. 8 mS cm(-1)). H-1 and C-13 solid state NMR studies the mX(2)O(5)-NSF composites demonstrate that the oligomeric nature of the NSF is preserved while in contact with the mX(2)O(5) surface, thus facilitating conductivity.