Formic acid oxidation on Pd/RuO2: does the RuO2 support enhance the electrocatalytic activity of Pd nanoparticles?

The aim of this work was to study the effect of a RuO2 support on the activity of Pd nanoparticles for formic acid oxidation, comparing the results with those obtained for Pd/C. In contrast with reports of enhancing effects of RuO2 for other systems, such as methanol oxidation on Pt particles, our data reveal a detrimental effect of the RuO2 support on the activity of Pd nanoparticles for the oxidation of formic acid. FTIR spectra show CO2 formation at potentials as low as 0.10 V and absence of adsorbed CO signals, suggesting that a bifunctional mechanism involving OH species on the oxide support surface does not occur nor has a significant contribution and that formic acid oxidation on Pd/RuO2 and Pd/C takes place by the direct pathway. The unfavorable effect of the RuO2 support on activity seems likely to be due to metal-support interactions that modify the Pd electronic properties. Graphical abstract: [Figure not available: see fulltext.]