Carbon supported Pd–Sn and Pd–Ru–Sn nanocatalysts for ethanol electro-oxidation in alkaline medium

Carbon supported Pd–Sn and Pd–Ru–Sn nanocatalysts were prepared by the chemical reduction method, using sodium borohydride and ethylene glycol mixture as the reducing agent. The catalytic activity towards ethanol electro-oxidation in alkaline medium was studied by cyclic, carbon monoxide stripping voltammetries and chronoamperometry. The current density obtained for the electro-oxidation was affected by varying ethanol concentration between 0.25 and 4 M. Raising ethanol concentration up to 3 M increased the coverage of the adsorbed ethoxy (CH3COads) species on the nanocatalyst surface, thus yielding an increase in current density. Pd–Sn/C displayed better electrocatalytic activity and stability towards poisoning than Pd–Ru–Sn/C and Pt–Ru/C (E-TEK Inc.) nanocatalysts. Transmission electron microscopy results showed that Pd–Sn and Pd–Ru–Sn nanoparticles were uniformly dispersed on carbon support. The average particle size of Pd–Sn was 7 ± 0.5 nm in diameter while for Pd–Ru–Sn was 6 ± 0.7 nm.

► Pd–Sn and Pd–Ru–Sn nanocatalyst were reduced by (NaBH4 + ethylene glycol) mixture.
► Pd–Ru–Sn/C (co-reduction) showed a lower performance than Pd–Ru–Sn/C (Pd+Ru–Sn/C).
► Varying ethanol concentration was found to affect the current density.
► Pd–Sn/C displayed better electrochemical activity and stability than Pd–Ru–Sn/C.
► The average particle size for Pd–Sn/C is 7 ± 0.5 nm.