One-pot synthesis of silica-titania binary nanoparticles with acid-base pairs: Via biomimetic mineralization to fabricate highly proton-conductive membranes

Simultaneous manipulation of vehicle-type and Grotthuss-type proton conduction within proton exchange membranes (PEMs) to induce satisfactory proton conductivity is crucial and challenging for promising environmentally friendly devices such as PEM fuel cells. In this study, a facile one-pot biomimetic mineralization approach is proposed for the construction of binary SiO2-TiO2 nanoparticles with a tunable ratio of silica to titania. Then the nanoparticles are functionalized by acid-base pairs and introduced into a Nafion matrix to fabricate novel hybrid membranes. The interaction between functional groups on SiO2-TiO2 binary nanoparticles and the polymer endows the hybrid membrane with good interfacial compatibility and enhanced dimensional stability. The incorporation of acid-base pairs reduces the activation energy for proton transfer; as a result, the hybrid membrane exhibits the highest proton conductivity of 1.37 × 10-2 S cm-1 at 26.1% RH and 80 °C, which is two orders of magnitude higher than that of recast Nafion. Compared with recast Nafion, a 51.3% increase in maximum power density is achieved for the Nafion/Si1-Ti2-160 hybrid membrane at 60 °C.