Role of the Metal-Oxide Support in the Catalytic Activity of Pd Nanoparticles for Ethanol Electrooxidation in Alkaline Media

The promotional role of oxide supports (CeO2, SnO2, TiO2) on ethanol electrooxidation in alkaline media over Pd nanoparticles (NPs) is presented and compared to Pd on carbon. XPS revealed a shift to lower binding energy of the Pd3d peak when Pd NPs were deposited on metal oxides, implying a charge transfer from the oxides to the Pd. The catalytic activity of the supported NPs for ethanol electrooxidation was assessed by using cyclic voltammetry and chronoamperometry. The electrooxidation products were monitored insitu, using polarization modulation-infrared reflection absorption spectroscopy (PM-IRRAS), which revealed that the supports influence the selectivity of reactions on Pd. Pd/CeO2 has superior selectivity towards breaking the C-C bond to produce CO2 compared to the other three supports. Acetate, as a product, was evident on all of the catalysts, but at different ratios. Pd supported on metal oxides showed higher activity and, in particular, CeO2 and SnO2 stand out as the best supports.