The effect of oxygen pretreatment on the morphological and electrochemical characteristics of a direct methanol fuel cell anode of different structures

Oxygen pretreatments on two types of carbon supports used in the anode of a direct methanol fuel cell (DMFC) was carried out to generate oxygen functional groups (OFGs) on their surfaces. These carbon supports, conventional carbon blacks and a special mesoporous carbon structure designated as CMK-1, were then deposited with platinum and ruthenium particles by a wet-incipient method. Transmission electron spectroscopy and X-ray diffraction spectroscopy were conducted to distinguish the surface morphologies of the prepared catalysts. In addition, the prepared catalysts were mixed with a liquid Nafion solution and pasted onto carbon paper to generate samples for electrochemical analyses in methanol solutions. Test results showed that the OFG treatment to the two types of carbon supports seemed to help in catalyst dispersion and in particle size reduction. The OFG-treated samples exhibited comparatively better catalytic activity for methanol oxidation and CO tolerance. In addition, the CMK-1 carbon support, whether OFG-treated or not, tended to favor the formation of a crystal structure by the catalyst that could alleviate the CO adsorption phenomenon.