Enhanced Electrooxidation of Ethanol Using Pd/C + TiO2 Electrocatalysts in Alkaline Media

This work describes the use of Pd nanoparticles synthetized by the borohydride process and supported on physical mixtures of C + TiO2 toward the ethanol electrooxidation reaction in alkaline media. In this study, the C/TiO2 ratios were studied by ranging the mass proportions of C/TiO2-100:0, 80:20, 60:40, 40:60, 20:80, and 0:100. X-ray diffraction patterns showed the presence of Pd face-centered cubic (fcc) structure, and carbon and TiO2 in rutile and anatase phases. Transmission electron micrographs showed metal nanoparticles with average particle size between 5.5 and 7.2 nm for all electrocatalysts. Cyclic voltammograms of Pd/C + TiO2 electrocatalysts showed a decrease of Pd surface area with the TiO2 increasing, while the linear sweep and chronoamperometric results showed the Pd/C + TiO2 (40:60) as the most promising electrocatalyst toward ethanol electrooxidation. The best results obtained with this catalyst were attributed to the presence of carbon and TiO2 in intermediate proportions since TiO2 supplies OH species and also changes the Pd d-band by a strong metal support interaction, increasing the alcohol oxidation without a significant decrease of conductivity and surface area.