Synthesis And Properties Of Nanostructured Cuprous Oxide And Copper Sulfides

Nanostructured cuprous oxide and copper sulfides powders have been prepared via a wet chemical route. Firstly, uniform Cu₂O nanospheres have been synthesized by reducing CuSO₄ with ascorbic acid in the sucrose solution, and the diameters of these nanospheres can be controlled in the range of 90-280 nm by changing the concentration of sucrose solution. Meanwhile, Cu₂O nanocubes (450 nm in edge length) are prepared with the coordination agent citrate. Cu₂O submicro-sized octahedron crystals (0.5-1.5μm in edge length) are prepared with the reducing agent glucose and the surfactant polyvinyl pyrrolidone. Secondly, Cu_7.2S₄ hollow nanospheres and nanoboxes are prepared from the reaction of the as-prepared Cu₂O nanospheres and nanocubes with Na₂S aqueous solution based on the Kirkendall effect, respectively. And the intermediates of the conversion, Cu₂O/Cu_7.2S₄ core/shell nanostructures have been recorded. Thirdly, by the subsequent treatment of Cu_7.2S₄ hollow samples with sodium citrate solution, CuS hollow nanospheres and nanoboxes are obtained. The samples are characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM). The reaction conditions are studied. Based on the experimental results, the possible formation mechanisms have been proposed.In addition, the adsorption effect of the methylene blue (MB) dye on Cu_7.2S₄ hollow nanospheres is investigated. The adsorption isotherms at different temperature (20℃, 35℃, 50℃) were determined respectively. The data analysis shows that the adsorption of MB on Cu_7.2S₄ hollow nanospheres obeys Freundlich and Langmuir equations. Further study indicates that the adsorption is a spontaneous endothermic process with a positive entropy changes.