Structural color materials have attracted extensive attention due to their fadeless color, low toxicity and environmentally friendly features, but the colors based on photonic crystal structures are usually angle-dependent on incident lights. In this research, we have fabricated a powder material with three-dimensional ordered macropores (3DOM) structure of silica (SiO 2 ) by a scarified template method . The micron-sized 3DOM SiO 2 powders can diffract lights in certain wavelengths and exhibits vivid structural colors. The structural colors from the 3DOM SiO 2 powder follows the Bragg diffraction of incident light on (111) stacked planes of the face-centered cubic colloidal crystals and the (111) crystal planes are randomly oriented. As a collective effect in the aggregation of micron-sized powders, the structural colors are angle-independent, and thus the 3DOM powders can be use as anti-reflective color coating material . In addition, because its diffraction can limit transmission and absorption of lights in some extent, so this 3DOM SiO 2 powder can be also used as protective coating material for reducing light radiations.
CO oxidation is the primary approach for eliminating CO from incomplete combustion, and the catalytic performance is dependent on the structure of catalysts. Herein, to explore the structure promotion in the CO oxidation reaction, polymethyl methacrylate was synthesized as the hard template to fabricate the three-dimensional ordered microporous (3DOM) Au/CeO 2 and compared the catalytic performance with the Au/CeO 2 rod catalyst. The 3DOM Au/CeO 2 catalyst could realize complete CO oxidation at 90 °C while 110 °C for Au/CeO 2 rod catalyst. The 3DOM Au/CeO 2 catalyst also showed outstanding stability for 60 h reaction. The achieved high performance could be attributed to the pore structures and the better metal-support interaction that facilitates abundant oxygen vacancies . Additionally, the Au distribution and oxygen vacancies promoted by the macropores structures were discovered using a series of characterizations. This work highlights the promotion of oxygen vacancies and metal-support interaction by 3DOM structure in CO oxidation reaction.
Jian Wang,Chao Yang,Ying-Rui Zhao,Hui-Ling Fan,Zhong-De Wang,Ju Shangguan,Jie Mi
Two types of cobalt oxide–silica composites were prepared by sol–gel method using different alcohols (n-butyl alcohol and ethylene glycol) in sol precursors. The corresponding adsorbents with 3DOM structure were also fabricated via a colloidal crystal template method. Physicochemical properties of the materials were characterized by means of numerous techniques, and the performance for hydrogen sulfide (H2S) removal were evaluated at room temperature. It was found that using n-butyl alcohol in sol precursors could achieve a material (SCN57-500) with plentiful ordered mesoporous in grains and thus had very large surface area (314.5 m2/g), whereas the sample obtained from ethylene glycol (SCE57-500) only possessed a smaller surface area. After introducing 3DOM structure into the bulk counterpart, the surface area improved remarkably as in the case of 3D-SCE57-500, which is consistent with our previous studies. However, 3D-SCN57-500 showed a decreased surface area compared with SCN57-500. The loss of surface area was due to the sharply decreased pores in grains, which is originated from sintering when the hard template was burning out during the preparation process. It can be deduced that the increased surface area after introducing 3DOM structure was ascribed to the excellent dispersion, i.e., the newly formed very small nanoscale grains. The results of adsorption experiments show that although SCN57-500 owned the highest surface area among these four adsorbents, however, it exhibited a poorest performance for H2S capture. Both 3DOM samples possessed very favorable breakthrough H2S capacity compared to the counterparts without 3DOM structure. The results indicated that size of crystalline or dispersion and not the surface area is what contributes to the reactivity of the adsorbent. The well-ordered and interconnected macropores play an important role as well. The breakthrough sulfur capacity of 3D-SCE57-500 could reach as high as 189 mg/g with Co3O4 utilization of 63%. The involved reactions for H2S removal by Co3O4 in experimental conditions were suggested.
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