Effect of acid functionalised carbon supports for Pd-Ni-Sn catalyst on ethanol oxidation reactionElectronic supplementary information (ESI) available. See DOI: 10.1039/c5ra07508d

The sodium borohydride reduction method was employed to prepare a ternary catalyst with an atomic ratio of 20%Pd10%Ni10%Sn impregnated on four carbon supports, Vulcan XC-72R carbon black (CB), functionalised carbon black (CB sn ), multi-walled carbon nanotubes (MWCNTs) and functionalised MWCNTs (MWCNT sn ), to improve the catalytic activity for direct ethanol fuel cells (DEFCs). The acid functionalisation was performed using H 2 SO 4 and HNO 3 . The addition of Ni and Sn metals helped to increase catalytic activity as well as catalyst stability in the ethanol oxidation reaction (EOR). The XRD and XPS results confirmed the presence of Ni(OH) 2 and SnO 2 compounds. The crystalline size was in the range of 6.4 to 7.4 nm for all samples. TEM images of the catalyst on MWCNT sn confirmed that the catalyst particles were uniformly distributed and dispersed with a particle size in the range of 6 nm. This result was consistent with the highest number of active sites investigated by CO chemisorption. This was due to the highly crystalline structure of MWCNT sn . Moreover, the catalyst on MWCNTs exhibited the highest current density (291 mA cm −2 ) for EOR, great catalyst stability, the highest electrochemical surface area (77.155 m 2 g −1 Pd) and excellent CO tolerance. The reduction method was used to prepare catalysts on carbon black (CB), functionalised carbon black (CB sn ), multi-walled carbon nanotubes (MWCNTs) and functionalised MWCNTs (MWCNT sn ) to improve the catalytic activity for ethanol oxidation reaction.