Effect of acid functionalised carbon supports for Pd–Ni–Sn catalyst on ethanol oxidation reaction†
Abstract
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 (CBsn), multi-walled carbon nanotubes (MWCNTs) and functionalised MWCNTs (MWCNTsn), to improve the catalytic activity for direct ethanol fuel cells (DEFCs). The acid functionalisation was performed using H2SO4 and HNO3. 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 SnO2 compounds. The crystalline size was in the range of 6.4 to 7.4 nm for all samples. TEM images of the catalyst on MWCNTsn 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 MWCNTsn. 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 m2 g−1 Pd) and excellent CO tolerance.
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