Diatomite-Assisted Synthesis of Ordered Mesoporous Carbon and Its Application in Fuel Cells

Abstract

Ordered mesoporous carbon has the promising development and potential in catalysis, because of its large amount of uniform pore size and high surface area. In this paper, ordered mesoporous carbon has been successfully synthesized via evaporation-induced self-assembly (EISA) method, using triblock copolymer Pluronic F127 as a soft template, resol as a carbon precursor and diatomaceous earth as the transient scaffolds. Diatomite is a kind of special biomaterial with 3D precision of tens of nanometers and of low price. Diatomite shells not only maintain the intact structure of the ordered mesoporous carbon, but also increase its aperture diameter and surface area to a certain degree, during the carbonization between 600 °C to 800 °C. When the samples were calcined in nitrogen, the features of diatomite could effectively reduce shrinkage ratio of sample structure, keeping the precursor fluid firmly adsorbed on the surface of diatom shells. The resulting materials were characterized by X-ray diffraction, transmission electron microscopy and N2 adsorption-desorption, etc. The results showed all the samples had highly ordered mesoporous structure. Under the support of diatomite, both of the specific surface area (717~773 m•g) and pore sizes (3.9~11.3 nm) of the mesoporous carbon have become much larger, which could be controlled by adjusting the ratio of diatomite to resol. The influence of the diatomite on the structure of the mesoporous carbon was discussed in the paper. Furthermore, we used the as-prepared ordered mesoporous carbon to load Pt nanoparticles. The Pt/carbon catalysts were prepared by microwave-assisted heating process with ethylene glycol as reductant. The electrocatalytic activity of carbon supported Pt nanoparticles was verified by cyclic voltammetry in CH3OH solution. We found the carbon materials with much larger specific surface areas had higher electrocatalytic activity. When the ratio of diatomite to resol was 0.5, the specific surface area of the sample was the largest, and the corresponding Pt/carbon showed the highest peak current of methanol oxidation.