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