Highly active Pd and Pd–Au nanoparticles supported on functionalized graphene nanoplatelets for enhanced formic acid oxidation

Pd and Pd–Au nanoparticles supported on poly(diallyldimethylammonium chloride) (PDDA) functionalizedgraphene nanoplatelets (GNP) have been synthesized by the ethylene glycol reduction method andcharacterized by transmission electron microscopy (TEM) and electrochemical measurements for formicacid oxidation. TEM analysis shows that the Pd–Au nanoparticles are uniformly distributed on the surfaceof graphene nanoplatelets with an average particle size of 6.8 nm. The Pd–Au nanoparticles supportedon PDDA–xGNP show higher activity for formic acid electro-oxidation than Pd nanoparticles supportedon PDDA–xGNP and Pd or Pd–Au supported on traditional Vulcan XC-72 carbon. The higher catalyticactivity of Pd–Au/PDDA–xGNP is mainly due to the alloying of Pd with Au. The promotional effect of Auand the absence of continuous Pd sites significantly suppress the poisoning effects of CO, enhancing thecatalytic activity for formic acid oxidation and making them promising for direct formic acid fuel cells(DFAFC).