Electrocatalytic Performance of Pd Catalyst Supported on Macropore Carbon for Oxidation of Formic Acid

The electrocatalytic performances of a Vulcan XC-72 carbon black supported Pd (Pd/XC) catalyst and a macroporous carbon supported Pd (Pd/MC) catalyst for formic acid oxidation in a direct formic acid fuel cell were investigated and compared. This was carried out using X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) spectroscopy, Raman spectroscopy, and electrochemical techniques. The cyclic voltammograms indicate that the main peak potentials for the oxidation of formic acid at the Pd/XC and Pd/MC catalyst electrodes are similar and they are located at about 0.15 V. However, the peak current density of the Pd/MC catalyst electrode is about 30% larger than that of the Pd/XC catalyst electrode. The chronoamperometric curves indicate that the peak current density at the Pd/MC catalyst electrode at 6000 s is about 38% larger than that at the Pd/XC catalyst electrode. These results show that the electrocatalytic activity and stability of the Pd/MC catalyst for the oxidation of formic acid are better than those of the Pd/XC catalyst. Because the average size and relative crystallinity of the Pd particles in the two catalysts are similar, the reason for the better electrocatalytic performance of the Pd/MC catalyst could be only attributed to its larger pore diameter and higher conductivity because of its high extent of MC graphitization