Ternary Triazole-Based Organic-Inorganic Proton-Conducting Hybrids Based on Computational Models for HT-PEMFC Application.

Abstract

We reported a new ternary hybrid anhydrous proton-conducting material based on triazole (Tz), wherein it interacted with TiO2 and cesium hydrogen sulfate (CHS) constructed based on the acid-base interaction. It exhibited high proton conductivity derived by the two acid-base interactions: between CHS and Tz and between Tz and TiO2. As a starting point of discussion, we attempted to theoretically predict the high/low proton conductivity using the push-pull protonated atomic distance (PAD) law, which makes it possible to predict the proton conductivity in the acid-base part based on density functional theory. The calculations indicate the possibility of achieving higher proton conductivity in the ternary composites (CHS·Tz-TiO2) involving two acid-base interactions than in binary hybrids, such as CHS·Tz and TiO2-Tz composites, suggesting the positive effect of two simultaneous acid-base interactions for achieving high proton conductivity. This result is supported by the experimental result with respect to synthesized materials obtained using the mechanochemical method. Adding TiO2 to the CHS·Tz system causes a change in the CHS·Tz interaction and promotes proton dissociation, producing a new and fast proton-conducting layer through the formation of Tz-TiO2 interaction. Applying CHS·Tz-TiO2 to high-temperature proton exchange membrane fuel cells results in improved membrane conductivity and power-generation properties at 150 °C under anhydrous conditions.