Electrocatalytic Activity of Pd<inf>20- x</inf>Ag<inf>x</inf> Nanoparticles Embedded in Carbon Nanotubes for Methanol Oxidation in Alkaline Media

Low Pd content and highly active bimetallic PdAg electrocatalytic nanoparticles supported on functionalized multiwalled carbon nanotubes (CNT) have been developed for the electrochemical methanol oxidation reaction (MOR). The polyol synthesis procedure is used to substitute Ag into Pd particles in a Pd/CNT matrix. The Pd20-xAgx/CNT samples (x wt % = 0, 5, 10, and 15) are characterized by XRD, XPS, Raman spectroscopy, and microscopy methods. The electrocatalytic activities and stabilities of Pd20-xAgx/CNT catalysts were examined by cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP) measurements for electrochemical oxidation of methanol in alkaline media. The Pd20-xAgx/CNT with x = 10 wt % is found to be a semialloyed sample and shows the best catalytic activity (731 mA mg-1) compared to the Pd/CNT catalyst (408 mA mg-1) and other samples. This semialloyed sample also shows long stability and high resistance toward CO poisoning. The semialloyed Pd10Ag10 particles with optimized metal ratio on CNT matrix would be a promising catalyst material for direct methanol fuel cell applications.