Template-free synthesis of ordered mesoporous carbon: Application as support of highly active Pt nanoparticles for the oxidation of organic fuels

Abstract

The electrochemical evaluation of Pt nanoparticles deposited on ordered mesoporous carbon (OMC) and multiwalled carbon nanotubes (MWCNT), by the polyol method was reported in this work. Their performances were evaluated for methanol, ethanol and ethylene glycol electro-oxidation reaction (MOR, EOR, and EGOR, respectively). The results have been compared with those of a Pt/Vulcan XC-72 catalyst prepared by the same procedure. OMC was synthesized via self-assembly in aqueous solution, as an alternative to other conventional preparation methods. MWCNT were synthesized by the spray pyrolysis technique. The three carbon supports were chemically modified prior to the Pt deposition and the changes on structural properties of OMC and MWCNT due such surface functionalization were characterized. Cyclic voltammetry results demonstrated that Pt/OMC has a lower on-set potential, delivering a higher anodic peak current density for the MOR, EOR and EGOR. Moreover, the jf/jb ratios at Pt/OMC were higher than those determined for Pt/MWCNT and Pt/Vulcan for the anodic reactions. The improvement in catalytic activity has been attributed to the mesoporous structure of OMC, which promoted a greater support–catalysts interaction. The use of OMC enhanced the tolerance to carbonaceous intermediates, thus inhibiting the self-poisoning of Pt nanoparticles. In addition, Pt/OMC exhibited electrochemically active surface area losses after accelerated degradation tests of 12%, a lower value compared with that of Pt/Vulcan (36%).