Pt@Nb-TiO<sub>2</sub> Catalyst Membranes Fabricated
by Electrospinning and Atomic Layer Deposition
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Abstract
A facile
method was developed to fabricate fibrous membranes of niobium-doped
titania-supported platinum catalysts (Pt@Nb-TiO<sub>2</sub>) by a
two-step approach. The process started with generating niobium-doped
titania (Nb-TiO<sub>2</sub>) 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@TiO<sub>2</sub> 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 H<sub>2</sub>-containing atmosphere, the ORR activity
became 0.28 mA/cm<sup>2</sup><sub>Pt</sub> at 0.9 V (vs RHE), because
of the improvement in conductivity of Nb-TiO<sub>2</sub> fibers and
better crystalinity of Pt NPs. The results of accelerated-stability
test showed that the Pt@Nb-TiO<sub>2</sub> 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