Photocatalytically Generated Bimetallic (Pt-Au/C-TiO2) Electrocatalysts for Polymer Electrolyte Fuel Cell Applications

Heterogeneous photocatalysis was used to prepare bimetallic Pt-Au modified carbon-TiO2 matrices for use in polymer electrolyte fuel cells. These new generation electrocatalysts were characterized by transmission electron microscopy, energy-dispersive X-ray analyses, X-ray diffraction, and X-ray photoelectron microscopy. The electrocatalytic activity of these materials for the oxygen reduction reaction (ORR) was assessed by rotating disk hydrodynamic voltammetry. Of the three variant scenarios that can be envisioned for photocatalytic deposition of the two metals, i.e., sequential deposition (with Pt first and Au second or Au first and Pt second) or simultaneous deposition of Pt and Au on the C-TiO2 nanocomposite surface from a single bath, electrocatalyst samples with Pt decorating the initially deposited Au nanoclusters (designated as Pt/Au/C-TiO2) performed the best in terms of ORR kinetic facility, even relative to the monometallic case of Pt supported on C-TiO2. The durability of these electrocatalysts (in terms of corrosion) was assessed via galvanostatic polarization tests; once again Pt/Au/C-TiO2 fared best relative to the other two samples as well as the Pt/C-TiO2 control case. For all the electrochemical analyses, the total metal loading in the electrocatalysts was kept constant at 20% (by mass) for meaningful comparison. (C) 2009 The Electrochemical Society. [DOI:10.1149/1.3251305] All rights reserved.