Solvothermal synthesis of Co sub(3)O sub(4)/Al sub(2)O sub(3) hollow core-shell microspheres for the catalytic oxidation of CO

A facile template-free solvothermal strategy has been developed for the synthesis of uniform and hollow core-shell Co sub(3)O sub(4)/Al sub(2)O sub(3) microspheres composed of numerous tiny nanorods. The morphology, structure, and composition of the spheres have been investigated using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, H sub(2)-temperature programmed reduction (H sub(2)-TPR) and X-ray diffraction analysis (XRD). The specific surface area and pore-size distribution of the obtained products as determined by gas sorption measurements show that the core-shell microspheres exhibit a high surface area and porosity. The formation of the hollow structure involves a trisodium citrate (TSC)-assisted Ostwald ripening process. The structure and factors that govern the shape evolution of the core-shell Co sub(3)O sub(4)/Al sub(2)O sub(3) microspheres have been carefully studied, such as the Co wt% content, the TSC/Al ratio and the temperature. The catalytic activity of the as-prepared core-shell Co sub(3)O sub(4)/Al sub(2)O sub(3) microspheres has been evaluated for CO catalytic oxidation. Their high performance may be attributed to their large specific surface area, high porosity and mesoporous structure.