Highly dispersed platinum supported on nitrogen-containing ordered mesoporous carbon for methanol electrochemical oxidation

Abstract

Nitrogen-containing ordered mesoporous carbons (NOMCs) characteristic of CMK-3 were nanocasted from mesoporous silica SBA-15 using aniline as carbon precursor. The influence of synthesis condition on the structural parameters of NOMCs were systematically investigated using N 2 adsorption, powder X-ray diffraction (XRD), transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis and thermogravimetric analysis (TGA). The 2D hexagonally ordered nitrogen-containing mesoporous carbon could be synthesized in a wide temperature range (600–950 °C), with Brunauer–Emmett–Teller (BET) surface area varying from 988 to 1166 m 2/g and pore size tunable from 2.7 to 3.3 nm. The N/C molar ratio in the framework of mesoporous carbon was found to be highly dependent on the synthesis condition and reduced from 9.5% to 4.8% as the synthesis temperature increased from 600 to 950 °C. XPS showed that nitrogen atoms were incorporated in graphitic sheets as quaternary nitrogen and pyridine-like nitrogen. The ca. 0.6 eV lower binding energy of Pt nanoparticles in contrast to that of bulk Pt indicated a strong interaction between nitrogen atoms and Pt nanoparticles, which was critical to the uniform dispersion of Pt nanoparticles on the nitrogen-containing mesoporous carbon. The CO stripping peak potentials depended on both the N/C ratio as well as Pt particles size. The activities of methanol oxidation on Pt/NOMCs were investigated by cyclic voltammograms and electrochemical impedance spectroscopy (EIS). The Pt/NOMCs showed generally high CO tolerance and comparable activity to Pt/XC-72 under the identical condition.