Synthesis And Characterization Of Porous CuO Hollow Microspheres

Due to their lower density and higher specific surface area, the hollow nano/microspheres exhibit unique and superior peformances compared with solid particles and may have great potential applications in many fields including optics, electricity and catalysis. In recent years, the controlled syntheses of hollow micro/nanospheres have received considerable attention.In this paper, the porous CuO hollow spheres were synthesized via two-step method and one-step method, respectively. The influences of different experimental parameters on the morphology of CuO structures were investigated in detail. The structures, properties and the possible formation mechanism of porous CuO hollow microspheres were also been proposed.The main works and results are as follows:(1) The size-controlled carbon spheres have been successfully synthesized by hydrothermal method at 160℃using glucose as carbon source. The surfaces of the spheres were hydrophilic and had a distribution of-OH and C=O groups.(2) The porous CuO hollow spheres have been successfully synthesized by using carbon spheres of 400nm as the templates, CuSO4·5H2O as copper source and glucose as the new carbon source. The influences of the concentration of CUSO4·5H2O, hydrothermal temperature and hydrothermal time on the morphology of CuO structures were investigated in detail. Results from SEM, EDS, XRD and FTIR were carried out to characterize the samples. The results show that the diameters of the microspheres range from 15μm to 20μm and the thickness of the shell is about 1μm. The surfaces of the spheres were porous and the products can be indexed as monoclinic phase CuO. The specific surface area of the hollow spheres with 74.805m2/g is measured by BET method. Barrett-Joyner-Halenda (BJH) calculations for the pore size distribution, derived from desorption data, reveal that the average pore radius is 8.56nm, and the total pore volume is 0.107257cc/g. On the basis of these results, the possible mechanism of its formation was discussed.(3) The porous CuO hollow spheres have been successfully synthesized via one-step method with different carbon sources. It was found that the experimental parameters, such as the concentration of CuSO4·5H2O, hydrothermal temperature and hydrothermal time, played crucial roles in the morphological control of porous CuO hollow spheres. When using glucose as carbon source, a large number of tubular structures were observed. The samples were characterized by SEM, XRD and FTIR. The results show that the the diameter of the microspheres is about 15μm and the thickness of the shell is about 1μm. The surfaces were porous and the products can be indexed as monoclinic phase CuO. The porous CuO hollow spheres prepared with sucrose have a much larger surface area of 409.302m2/g, a total pore volume of 0.256419cc/g, and an average pore radius of 3.15nm. The possible mechanism of the formation of the porous CuO hollow spheres synthesized via one-step method using glucose as carbon source was also disscussed.(4) The UV-vis adsorption and photocatalytic activity of the porous CuO hollow microspheres via two-step method and one-step method for the degradation of RhB have been investigated, respectively. The porous CuO hollow spheres synthesized via different method exhibited superior optical properties. It is found that porous CuO hollow microspheres prepared with sucrose had a higher photocatalytic activity for degradation of Rhodamine B aqueous solution, which can be attributed to their larger surface area and more pore capacious interspaces.