Exceptionally thermal-stable Al2O3/TiO2 nanofibers by depressing surface-initiated grain growth as new supports for anti-sintering Pt nanoparticles

Electrospun ceramic nanofibers can be ideal supports for catalyst, but commonly restricted by the rapid grain growth during fabrication and thus lose their superior functions. In this work, we reported grain growth suppressed nanofibers made of a blend of TiO2 and Al2O3 with an average crystal size of 22.2 nm and 47.1 wt% of anatase on 900 °C. Al2O3 preferred to locate at the grain boundaries of TiO2 nanograins, significantly hindering the coalescence among the neighboring TiO2 nanograins. More intriguingly, Al2O3 spontaneously migrated to the surface and thus naturally formed a particle-on-fiber morphology. When serving as support, Al2O3/TiO2 nanofibers offered promoted adhesion for Pt nanoparticles, by taking advantages of the well-preserved grain boundaries and anatase phase. Moreover, the dual-oxide construction built kinetic bottleneck to prevent Pt nanoparticles from moving across the support to attach to or merge with each other. Therefore, Pt nanoparticles can be stabilized against sintering up to 500 °C with an ultra-close neighboring distance of 4.56 nm. This sinter-resistant catalyst exhibited high activities toward both liquid-phase hydrogenation and gas-phase oxidation reactions (i.e. soot oxidation) at high temperatures. Such a robust and thermally stable catalyst can be further used for catalytic soot oxidation, giving great prospects for emission control.