No abstract

Proton conductivity in a series of mesoporous niobium and tantalum metal oxide (mX2 O5 ) composites of naphthalene sulfonic acid formaldehyde resin (NSF) that are resistant to moisture loss at temperatures greater than 50 °C is reported. The investigation focuses on the effect to proton conductivity by changing pore size and metal in the mesostructure of the mX2 O5 system and thus, a series of mX2 O5 -NSF composites were synthesized with C6 , C12 , and C18 templates. These were characterized by XRD, thermogravimetric analysis, nitrogen adsorption, and scanning TEM and then studied using impedance spectroscopy to establish proton conductivity values at various temperatures ranging from 25 to 150 °C. The most promising sample displayed a conductivity of 21.96 mS cm(-1) at 100 °C, surpassing the literature value for Nafion 117 (ca. 8 mS cm(-1) ). (1) H and (13) C solid state NMR studies the mX2 O5 -NSF composites demonstrate that the oligomeric nature of the NSF is preserved while in contact with the mX2 O5 surface, thus facilitating conductivity.

Proton conductivity and thermald urability studies were performed on as eries of mesoporous Nb 2 O 5 composites with naphthalene sulfonate formaldehyde resin polymerized within the pores. The proximity of the sulfonate groups of the polymer to the walls of the oxide mesostructure was deliberately tailored to ensure superior dehydration resistance crucial to proton conductivity.I nitially characterized by nitrogen adsorption, XRD,T GA and STEM, subsequent study using impedance spectroscopy over at emperature range of 20-150 8Ce stablished their proton conductivity performance. The most promising sample displayed aconductivityo f2 1.77 mS cm À1 at 80 8Cs urpassingt he literature value for Nafion 117( 8mScm À1)a sm easured in our labs using the same setup. Subsequent thermal durability tests demonstrated that this composite maintains superiorc onductivity to Nafion 117a t8 08Cf or the length of the study (24 h). These observations were rationalized by in depth solid-state NMR studies.

The Back Cover image shows the movement of protons along an enhanced proton‐conducting pathway fabricated inside a mesoporous transition‐metal oxide impregnated with naphthalene sulfonate formaldehyde resin. Ambient moisture and the sulfonate groups of the 4–6‐unit oligomers bind to the Lewis acidic walls of the mesostructure, creating a channel for enhanced proton conduction at the interface. As protons enter the pores, they hop along the proximal oxygen sites, giving rise to proton conductivity values surpassing those of the Nafion standard used in the study. More details can be found in the Full Paper by Turley et al. on page 301 (DOI: ).