Study On Preparation Of Rare Earth Oxide Hollow Spheres By Carbon Spheres Templates And Functionalization

Inorganic hollow nano/microspheres of uniform size and shape have attracted considerable research interest owing to their low density,large specific surface area,good surface permeability properties as well as encapsulation ability,and a wide range of potential applications such as catalysis,chemical sensors,lithium-ion batteries,controlled release capsules,photonic devices,etc.Compared with rare earth oxide,rare earth oxide hollow microspheres combined with the special properties of rare earth oxide and the structure effect of hollow microspheres,while its applications on the optical,electronic,magnetic and catalytic properties were greatly extended.Recently,study on preparation and functionalization of rare earth oxide hollow spheres have attracted enormous attention at home and abroad.The monodispersed carbon spheres was prepared by hydrothermal method using glucose and deionized water as raw material and formaldehyde auxiliary in the paper.The influence of the synthesis condition on the shape and particle size of the carbon spheres has been explored.Then,the uniform rare-earth ytterbium oxide(Yb2O3)hollow microspheres and gadolinium oxide(Gd2O3)hollow microspheres have been successfully prepared via a urea-based homogenous precipitation method using carbon spheres as template,followed by a heat treatment,respectively.The main synthesis process was carried out in aqueous conditions without any organic solvents,surfactants,or etching agents.X-ray diffraction,Fourier transformed infared spectroscopy,thermogravimetry,X-ray photoelectron spectroscopy,scanning electron microscopy,transmission electron microscopy,UV-visible spectrophotometer,Brunauer-Emmett-Telletr surface area measurement were employed to characterize the structure,morphology and performance of the samples.The contents and results mainly as follows:1.The Previous hydrothermal method of preparing carbon nano/microsoheres,often have the shortcomings of poor monodispersity and uniformity.In this paper,the carbon spheres has been synthesized by a hydrothermal method using glucose as raw material,adopting the formaldehyde auxiliary.The influence of the hydrothermal reaction time and temperatures,raw material ratio and p H value on the morphology and structure of the obtained microsphere were discusssed.The SEM images and LPS show that the concentration of the glucose,reaction temperature and reaction time has a significant influence on the diameters of the spheres.The dimension of carbon spheres increases with increasing concentration of the glucose,reaction temperature and reaction time.The main reason for this can be attributed to the improvement of the degree of dehydration and polymerization of the glucose.FTIR result showed that the as-prepared carbon spheres is hydrophilic and have a distribution of O-H and C=O groups on the surface.XRD result showed that the as-prepared carbon spheres is amorphous.2.Uniform rare-earth gadolinium oxide(Gd2O3)hollow microspheres,as-formed through a urea-assisted homogenous precipitation process using carbon spheres as template and a subsequent heat treatment.The results indicate that final products can be indexed to cubic Gd2O3 phase with high purity and have a uniform morphology with 500 nm in diameter and 20 nm in shell thickness.The Brunauer-Emmett-Telletr(BET)surface area is 15.2 m2/g,and the pore volume is 0.051 cm3/g,the result reveals that the Gd2O3 hollow microspheres have mesoporous pore shell.The form mechanism of Gd2O3 hollow spheres was analyzed.The possible mechanism for the formation of the Gd2O3 hollow microspheres can be mainly divided into three stages.Firstly,the carbon spheres templates were formed by hydrothermal;Secondly,the core-shell structured precursor was obtained by the homogeneous precipitation;Finally,Gd2O3 hollow microspheres was obtained during the calcination process.The as-synthesized Gd2O3 hollow microspheres exhibited a superior photocatalytic activity than commercial Gd2O3 powder3.Uniform rare-earth ytterbium oxide(Yb2O3)hollow microspheres have been successfully prepared via a urea-based homogenous precipitation method using carbon spheres as template,followed by a heat treatment.SEM results show that when ytterbium nitrate pentahydrate is 0.6 mmol,got the best effect of covering core-shell structure MF/Yb(OH)CO3 composite microspheres.The as-obtained Yb2O3 microspheres with spherical shape and hollow structure are uniform in size and distribution of about 450 nm and wall thickness of approximate 15 nm.