Enhanced electro-oxidation of ethanol using PD/C+TiO₂ electrocatalysts in alkaline media

Full text: Alkaline direct ethanol fuel cell (ADEFC) has been attracting more attention due to the high specific energy, low toxicity and easiness of ethanol production from biomass. However, the main obstacle of ADEFC is the low kinetic in low temperatures. Considering these aspects, many substrates are being used and among them TiO₂ has attracted much attention due to its high corrosion-resistance in fuel cell working environment, stability, low cost and special photoelectric properties [1]. Aiming the improvement of ethanol oxidation this work describes the use of Pd nanoparticles synthetized by the borohydride process and supported on physical mixtures of C+TiO₂ toward the ethanol electro-oxidation 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, 0:100. X-ray diffraction patterns showed the presence of Pd face-centered-cubic structure, carbon and TiO₂ in rutile and anatase phases. Transmission electron micrographs showed metal nanoparticles with average particles size between 5.5 and 7.2 nm. Cyclic voltammograms of Pd/C+TiO₂ electrocatalysts showed a decrease of Pd surface with the TiO₂ increasing, while the linear sweep and chronoamperometric results showed the Pd/C+Ti₂ (40:60) as the most promising material toward ethanol electro-oxidation. The best result was attributed to the presence of carbon and TiO₂ in intermediates proportions since TiO₂ supply OH species and also changes the Pd d-band by a strong metal support interaction without higher decrease of superficial area. References [1] ST Nguyen, Y Yang, X Wang, Ethanol electro-oxidation activity of Nb-doped-TIO₂ supported PdAg catalysts in alkaline media, Appl Catal B-Environ, 113-114 (2012) 261-270. (author)