TiO2/C composite as a support for Pd-nanoparticles toward the electrocatalytic oxidation of methanol in alkaline media

Abstract

The electro-oxidation of methanol was studied in alkaline solution on Pd nanoparticles supported on carbon black (XC-72R, C) and TiO2/C composite. The materials were prepared via organic colloid route at 170°C with 5wt% of Pd. X-ray diffraction (XRD), PdO monolayer reduction (PdOred) and CO-stripping was employed to characterize both structure and electrochemical properties. According to this, the lattice parameter decreases from 0.3991 to 0.3905nm due to a possible formation of Pd–Ti alloy. This modification is linked with the electrochemical active surface area (ECSA) decreasing from 22 to 18m2g−1. On the other hand, studies as a function of temperature and alcohol concentration indicated that the current for methanol electro-oxidation is higher and more stable at Pd/TiO2–C, with Ea=44.042kJmol−1. Then, it is highly possible that at Pd/TiO2–C, the OH−/OHads couple is adsorbed at the TiO2 sites, increasing the kinetic of methanol oxidation reaction at the catalyst surface.