(Invited) Comparative Study of the Electrocatalytic Oxidation of Glycerol on Pd-Au/CMO and Pd-Au/MWCNT Nanocatalysts Prepared by the Polyol Method in Alkaline Media

Studies on fuel cells are currently increasing because of their great potential for portable, transport and stationary power supply applications. Recently, the use of alkaline electrolytes has called the attention of several groups worldwide because the electrochemical kinetics occurring at fuel cell electrodes is enhanced, and platinum-free catalysts that otherwise show low activity in acid media can be used. In alkaline DAFCs, the use of polyols as fuels is an interesting alternative. Particularly, glycerol is less toxic than methanol and has a relatively high theoretical energy density (5.0 kWh kg^-1) compared to methanol (6.1 kWh kg^-1). Pd has been known to exhibit superior activity for the glycerol electro-oxidation in alkaline solution. Beside this, the combination of Pd and Au has exhibited a synergetic effect increasing the catalytic activity for selective oxidation of polyols. In this work, the influence of two carbon supports on the electrocatalytic performance of Pd-Au materials for the glycerol oxidation reaction in KOH electrolyte is investigated. Pd-Au/OMC and Pd-Au/MWCNT have been synthesized by the polyol reduction method. The catalysts have been characterized by XRD, EDS, TEM and electrochemical techniques. The results show the influence of the carbon support on the catalytic activity of the Pd-Au anodes. Such effect could be attributed to the fact that the relatively large pores in the OMC support facilitate the mass transfer process, promoting a high concentration of exposed active sites to participate in the reaction.