Titania Nanotube Arrays (TNAs) as Support for Oxygen Reduction Reaction (ORR) Platinum Thin Film Catalysts

Recently, we showed that Nb-doped bulk TiO2 electrodes can be functionalized with minute amounts of Pt via CO-terminated Pt deposition but optimization of the conductivity of these electrodes via proton intercalation did not change the catalytic activity of the Pt deposits. Here, it is shown that intercalation of H species in 0.27 wt% NH4F in glycol raises the catalytic activity of Pt deposited in a CO-terminated fashion if it is used on nanostructured (titania nanotube arrays) rather than titania bulk electrodes. Catalyst support tuning becomes feasible for nanostructures but effects of the intercalation treatment fade away within days. Moreover, catalytic activities of ultra-low Pt amounts, as determined by ICP-MS, on TNAs are very low compared to deposition on gold. This effect is attributed to high strain exerted on the Pt thin layers by the oxide support.