Electro-oxidation of methanol on SnO₂-promoted Pd/MWCNTs catalysts in alkaline solution

The methanol electro-oxidation (MEO) on Pd-SnO₂/MWCNTs catalysts prepared by microwave-assisted polyol reduction method has been investigated. The structure, morphology and electro-catalytic performances of the catalysts were characterized with XRD, TEM and cyclic voltammetry (CV). The results showed that the highly dispersed Pd nano-particles (PdNPs) with a narrow size distribution on MWCNTs were successfully synthesized. The catalytic activity of Pd-SnO₂/MWCNTs for MEO was up to 778.8 mA/mg Pd in 0.1 M KOH solution containing 1 M methanol, which was significant higher than that of Pd/C (414.2 mA/mg Pd) or Pd-SnO₂/C (566.7 mA/mg Pd). Moreover, the MEO on Pd-SnO₂/MWCNTs electrode displayed an irreversible behavior under a diffusion control giving an exchange current density (j⁰) of 3.76 × 10^-4 A cm^-2 and a Tafel slope of 149 mV dec ^-1 (α = 0.56) at 25 °C, which indicates that Pd-SnO ₂/MWCNTs catalyst has a high electro-catalytic performance for the MEO in alkaline media.