Influence of nanostructured ceria support on platinum nanoparticles for methanol electrooxidation in alkaline media

Abstract

The catalytic activity of platinum (Pt) nanoparticles (NPs) towards methanol electrooxidation in alkaline media was demonstrated to be dependent on their interactions with their nanostructured ceria support. Ceria nanorods (NRs) with diameters of 5 to 10 nm and lengths of 15 to 50 nm as well as ceria NPs with diameters of 2 to 6 nm were applied as supports for similarly sized Pt NPs with diameters of 2 to 5 nm. Cyclic voltammetry data showed that Pt NPs supported on ceria NPs exhibited a 2-to-5-fold higher catalytic current density versus ceria NRs. X-ray photoelectron spectroscopic data indicated that Pt NPs deposited onto ceria NRs were disproportionally composed of oxidized species (Pt²⁺, Pt⁴⁺ and Pt–O–M) rather than Pt⁰ while Pt NPs on ceria NPs mainly consisted of Pt⁰. Stronger metal-support interactions between Pt NPs and ceria NRs are postulated to induce preferential oxidation of Pt NPs and consequently decrease the catalytic sites and overall activity.