Synthesis And Characterization Of Three-dimensionally Ordered Macroporous Materials Based On SiO₂ Opal

Three-dimensionally ordered macroporous (3DOM) materials have shown wide application prospects in the fields of adsorption/separation, catalysis, filtration, photoelectron, and electrochemistry because of their uniform tunable pore sizes and three-dimensionally ordered macropores which connected to each other. In recent years, hierarchically meso-macroporous materials containing both interconnected mesoporous and 3DOM structures became one of the research hotspots in the fields of porous materials. The hierarchically meso-macroporous materials have high BET surface areas and large pore volumes. The 3DOM structure in the materials improved the transmission efficiency of the substances greatly and provided a good approach to solve the pore size restriction of the ordered mesoporous materials. In this paper, hierarchically meso-macroporous carbons with different mesoporous structures were fabricated and characterized. The electrochemical behaviors of the representative product were studied. In addition, the synthesis and structure of the ordered macroporous metal oxide microspheres were also studied. The as-made samples were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and nitrogen adsorption-desorption isotherm measurement.Monodisperse SiO₂ microspheres with diameters of 190～400 nm were synthesized by a modified St?ber method. Three-dimensionally ordered SiO₂ opals were prepared by using the synthesized monodisperse SiO₂ microspheres via a self-assembled sedimentation route. A series of hierarchically ordered meso-macroporous carbon materials were synthesized via a solvent evaporation induced self-assembly (EISA) pathway by using the obtained SiO₂ opal as a hard template, amphiphilic triblock copolymer F127 or P123 as soft templates, and phenolic resin as carbon source. The nitrogen adsorption-desorption measurements showed that the samples had high BET surface areas, large pore sizes and pore volumes. This indicated that the opal templates confined the shrinkage of the mesoporous pores effectively in the process of the carbonization. The electrochemical characterizations of the representative product indicated that the supercapacitive performances of the product were better than those of the single ordered mesoporous carbon. The uniform ordered macroporous Co3O4 and CeO₂ microspheres with novel structures were also synthesized via an easy melt infiltration route. SiO₂ opal is used as a hard template and Co(NO3)2·6H2O or Ce(NO3)3·6H2O as the precursors. This method provides a good approach for preparing ordered macroporous oxide materials.