In
the present study we compare different nanoparticle (NP) composites (nanocomposites)
as potential electrocatalysts for the oxygen reduction reaction (ORR). The
nanocomposites consist of a mixture of Pt and Ir NPs and Pt and Au NPs,
respectively, that are immobilized onto a high surface area carbon support. Pt NPs
supported on the same carbon support serve as benchmark. The performance
testing was performed in a conventional rotating disk electrode (RDE) setup as
well as in a recently introduced gas diffusion electrode (GDE) setup providing
high mass transport conditions. The ORR activity is determined, and the
degradation tested using accelerated degradation tests (ADTs). It is shown that with respect to the benchmark,
the Pt – Au nanocomposite
concept exhibits improved ORR activity as well as improved stability both in
the RDE and the GDE measurements. By comparison, the Pt – Ir nanocomposite
exhibits improved stability but lower ORR activity. Combining the GDE approach
with small angle X-ray scattering, it is shown that the improved stability of the Pt – Au nanocomposite can be assigned to a reduced Pt particle growth
due to the adjacent Au NPs. The results demonstrate that nanocomposites could
be an alternative catalyst design strategy complementing the state-of-the-art
alloying concepts.<br>
Elucidating Pt-Based Nanocomposite Catalysts for the Oxygen Reduction Reaction in Rotating Disk Electrode and Gas Diffusion Electrode Measurements