Nickel-catalyzed fabrication of SiO2, TiO2/ graphitized carbon, and the resultant graphitized carbon with periodically macroporous structure

Abstract

In this work, we present a facile route to fabricate three-dimensionally ordered macroporous SiO2/graphitized carbon, TiO2/ graphitized carbon, and the resultant graphitic carbon. The graphitized carbons were formed by catalytic graphitization of polystyrene arrays, which were used as both template and carbon source for the generation of macroporous composite. The prepared samples were characterized via powder X-ray diffraction, Raman spectroscopy, SEM, TEM, HRTEM, thermogravimetic analysis, and N2 adsorption. The graphitization degree and the content of graphitic carbon in the composite were dependent on the pyrolysis temperature and confinement effect of macroporous oxides skeleton. The composite of SiO2/graphitized carbon exhibited long-range ordered structure at the pyrolysis temperature ranging from 600 to 1000°C. The low pyrolysis temperature leads to the low degree of graphitization and low content of graphitic carbon in the composite. After the SiO2 skeleton was removed, depending on the carbon content and the graphitization extent in the SiO2/graphitized carbon composite, the resultant graphitic carbons display either collapsed or ordered macroporous structure. Based on the HRTEM, the interlayer distance of graphitized carbon at a pyrolysis temperature of 900°C is estimated to be 0.348 nm. In comparison with SiO2/graphitized carbon, the composite of TiO2/graphitized carbon exhibits less ordering but slightly higher surface area. The photoactivity of TiO2/graphitized carbon was examined and compared to commercial P25 and the composite of TiO 2/amorphous carbon in terms of degradation of Rhodamine B and eosin Y aqueous solution. It was found the TiO2/graphitized carbon showed higher activity than TiO2/amorphous carbon and P25 in the degradation of Rhodamine B and activity comparable to that of P25 in the degradation of eosin Y. © 2007 American Chemical Society.