Pt@Nb-TiO₂ catalyst membranes fabricated by electrospinning and atomic layer deposition

A facile method was developed to fabricate fibrous membranes of niobium-doped titania-supported platinum catalysts (Pt@Nb-TiO₂) by a two-step approach. The process started with generating niobium-doped titania (Nb-TiO₂) fibrous membranes by electrospinning, followed by the deposition of Pt nanoparticles (NPs) using an atomic layer deposition (ALD) technique. The area-specific oxygen reduction reaction (ORR) activity of Pt@TiO₂ catalyst membrane was increased by ∼20 folds if 10 at.% of Nb was incorporated into the ceramic fibers. The area-specific activity also increased with the number of ALD cycles, because of the increase of the Pt loading in the catalysts. After post-treatment of the catalyst membrane at high temperature in H₂-containing atmosphere, the ORR activity became 0.28 mA/cm²_Pt at 0.9 V (vs RHE), because of the improvement in conductivity of Nb-TiO₂ fibers and better crystalinity of Pt NPs. The results of accelerated-stability test showed that the Pt@Nb-TiO₂ catalyst membrane was highly stable and lost only 10% of its initial activity after 30 000 potential cycles (0.6 to 1.0 V vs RHE) under a strong acidic condition.