Electrocatalytic Performance and Formic Acid Tolerance Ability of Macropore Carbon Supported Ir Catalyst for Oxygen Reduction

The electrocatalytic performance and formic acid tolerance ability of the Vulcan XC-72 carbon black supported Ir(Ir/XC) catalyst and the macropore carbon supported Ir(Ir/MC) catalyst in the direct formic acid fuel cell were investigated by energy dispersive spectroscopy( EDS), X-ray diffraction( XRD) spectroscopy, Raman spectroscopy and electrochemical technique. It is found that the electrocatalytic performance of the Ir/MC catalyst for the oxygen reduction is better than that of the Ir/XC catalyst. The onset reduction potential of oxygen at the Ir/MC catalyst is 0. 1 V more positive than that at the Ir/XC catalyst. The limiting current density of the oxygen reduction at the Ir/MC catalyst is 30% larger than that at the Ir/XC catalyst. This could be only attributed to the large pore diameter and porosity as well as high graphitization extent because the average diameters and relative crystallinity of the two catalysts are similar. In addition, both catalysts have good formic acid tolerance ability. Therefore, MC is a better carbon carrier of the catalyst than XC