Application of a composite structure of carbon nanoparticles and Nb-TiO2 nanofibers as electrocatalyst support for PEM fuel cells

Platinum catalyst nanoparticles (20 wt.%) were deposited on a mixed support, which consisted of 25 at.% Nb doped TiO2 nanofibers and carbon agglomerates. XRD analysis revealed that titania was present in the rutile phase. The catalyst was characterized electrochemically with respect to durability and oxygen reduction activity. Based on cyclic voltammetry tests, the Nb-TiO2/C supported catalyst was more stable compared to a commercially available carbon supported Pt catalyst (E-tek) over 1000 cycles. The apparent active Pt area decreased by 5% due to cycling, whereas in the case of Pt/C the decrease was 23%. The oxygen reduction performance was comparable for both cases. For example, during the anodic sweep the mass activity at 0.9V vs. the reversible hydrogen electrode (RHE) was 19 A g(Pt)(-1) and 20 A g(Pt)(-1) for the freshly prepared in-house prepared and commercial catalysts, respectively. After the durability experiment both types of catalysts yielded a mass activity of 17 A g(Pt)(-1). Fuel cell tests with a single cell configuration were also carried out with the Nb-TiO2/C supported catalyst on the cathode side (gas diffusion electrode), yielding a peak power density of 0.34 W cm(-2) at 75 degrees C when pure oxygen was supplied on the cathode side. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.