Research Of Hollow Microstructural Oxides Prepared Via Yeast Templating Method

Hollow metal oxide microstructure has the characteristics such as lower density,higher surface area and other better properties which make it has a number of the performance that the block material does not have. The hollow microstructures have attracted tremendous attention because of the great potentials in many areas such as environmental protection, energy storage and biomedicine. The template preparation method is the main method of fabricating hollow particles. Compared with traditional templates, the biological templates have advantages of morphological diversity, large numbers of individuals and environment friendly, mild reaction conditions, convenient operations. At the same time, due to its extremely rich in species, the biological templates method becomes research focus in synthesis of hollow metal oxide.In this paper, via bio-template and precipitation method using facile spherical yeast as natural template, CeO2 microspheres with well-defined hollow structure were obtained after high-temperature calcination. The influences of the concentration of [Ce(SO4)2·4H20], the aging time, the calcination temperature and the influences of surfactant on the morphologies and crystal phases of the final products have been investigated. The products were characterized by X-ray diffraction, Fourier transform infrared, X-ray photoelectron spectra, scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption isotherms. The possible formation mechanism of CeO2 hollow microspheres has been proposed and the optical performance of CeO2 hollow microspheres was tested.The experimental results showed that when there was distilled water solvent system and no surfactant added,the concentration of [Ce(SO4)2·4H2O] was 0.5 mol·L-1 and NaOH was 1 mol·L-1, the aging time were 12 hours and the calcination temperature were 600?, the finely dispersed and regular shape CeO2 hollow microspheres with an average edge length of 2.0 ?m?3.0?m were obtained. The cubic crystal structure CeO2 hollow microspheres retain the appearance of the yeasts and the shape were approximately ellipsoid.The CeO2 hollow microspheres were used as photocatalyst to study the photocatalytic degradation performance of dye wastewater. The specific surface area of the sample is 21.85 m2·g-1 which is higher than the sample prepared without templates. The band gap energy of the CeO2 hollow microsphere (3.03 eV) is small compared with the samples prepared without templates (3.42 eV) via UV-Vis diffuse reflectance spectrum. The synthesized CeO2 hollow microspheres exhibit good photocatalytic activity for photodegradation of acid orange 7 (AO 7) aqueous solution under solar light irradiation. The degradation rate of AO 7 can be 96% after 120 min which is much higher than that of samples prepared without templates.In2O3 hollow microspheres were synthesized by yeast as templates and by employing indium nitrate and sodium hydroxide after high temperature calcined.Through the analysis and characterization, the In2O3 hollow microspheres retain the appearance of the yeasts with the specific surface area of 19.23m2·g-1. The band gap energy of In2O3 hollow microsphere is 3.28 eV which may made the samples have solar light catalytic potential. The degradation rate of methylene blue can be 91.91%after 180 min under solar light irradiation.