RuO₂-SiO₂ mixed oxides as corrosion-resistant catalyst supports for polymer electrolyte fuel cells

The objective of this study was to evaluate the suitability of mixed oxides of silica (SiO₂) and ruthenia (RuO₂) for use as electrocatalyst supports in polymer electrolyte fuel cells (PEFCs). The RuO₂:SiO₂ oxides were synthesized in three different molar ratios (0.1:0.9, 0.3:0.7 and 0.5:0.5). Of these formulations, RuO₂-SiO₂ (0.5:0.5) displayed high BET surface area (~290m²g^-1), high electronic conductivity (>5Scm^-1), and outstanding electrochemical stability (change in double layer capacitance of <10% compared to 360% for Vulcan XC72 carbon upon rigorous accelerated potential cycling tests that mimic automotive drive cycles). The RuO₂-SiO₂ (0.5:0.5) support material was subsequently catalyzed by deposition of 24wt% of platinum nanoparticles. The resultant electrocatalyst yielded a mass activity of 50mAmg_Pt^-1 and an area specific activity of 156.3μAcm^-2 at 0.9V vs. RHE when tested in a fuel cell operating at 80°C and 75% relative humidity.