Glycerol electrooxidation catalyzed by Pt-Sb supported in periodic mesoporous carbon CMK-3 and CMK-5

Glycerol is a biomass-derivative feedstock with potential use in direct alcohol fuel cells. In this work, we have studied the influence of distinct carbon-supports for N-Sb catalysts applied to glycerol electrooxidation reaction. The carbon matrixes were synthesized from Si templates with distinct geometries, giving the so-called CMK-3 and CMK-5, whose 3D structures were characterized employing SAXS, TGA, TEM, and N-2 adsorption isotherms. N nanoparticles were synthesized onto the carbon structures (Pt/C-x within X = CMK-3, CMK-5, or Vulcan) and converted to Pt-Sb/C catalysts by irreversible Sb2O3 adsorption on Pt/C-x covering up to 97% of N surface as inferred by cyclic voltammograms. Regardless of the carbon support, the onset of glycerol oxidation on N-Sb/C is ca 0.4 V (vs RHE), however, at higher potentials in cyclic voltammetric conditions or chroamperometric curves, Pt-Sb/CCMK-3 depicted the best activity among the synthesized catalysts, providing currents 1.6 and 2.0 times bigger than those in Pt-Sb/CCMK-5, and Pt-Sb/C-vulcan, respectively after 800 s at 0.5 V. The results are explained utilizing the coupled between the glycerol mass transport from bulk to active sites in carbon matrixes and re-adsorption of partially oxidized reaction products.