Synthesis Of Copper Oxide-Based Micro/Nano Materials With Hierachical Structures And Their Photochemical Properties

Recent years, transition metal oxides has been a hot topic among the studies on materials science because of its unique physical and chemical properties. However, it is still a huge challenge to control the morphology, structure and particle size during the preparation of the transition metal oxides. In our work, two kinds of the copper oxide-based micro/nano materials with hierachical structures were prepared by simple solvothermal method. And the evolution processes was explored. In addition, superior photochemical performance properties of the copper oxide-based micro/nanomaterials in the degradation of organic pollutants compared to the other samples has been demonstrated. The main contents and novelties were summarized as follows:(1) Monodispersed and uniform Cu-EG complex with ball-in-ball hollow structures was synthesized via a simple, environmentally-friendly method, employing ethylene glycol(EG) as a solvent/additive and Cu(CH3COO)2·H2O as copper source. Ostwald ripening was the main formation mechanism for the ball-in-ball hollow spheres. Additionally, polyvinylpyrrolidone(PVP) was used in our reaction system. And it can control the size uniformity of particle. After calcination in air, Cu O ball-in-ball hollow spheres were successfully prepared, which retained the morphology of the parent Cu-EG complex structures. Such Cu O ball-in-ball hollow spheres can serve as a potential photocatalyst for the degradation of Rhodamine B(Rh B) under visible light irradiation and in the presence of hydroxide water(H2O2). The results suggest that the photocatalytic activity of monodispersed Cu O ball-in-ball hollow spheres was 3.65 times faster than that of the commercial Cu O powders. Such a preferable photocatalytic activity was mainly attributed to the unique ball-in-ball hollow structures which can be able to multiple light reflections and scattering between the outer spherical shell and the interior core compared with the commercial Cu O powders to provide a more efficient way to enhance light-harvesting efficiency.After five successive cycles, 87% of Rhodamine B was photodegraded and the photocatalytic activity of the as-prepared Cu O ball-in-ball hollow spheres almost remains unchanged. This indicated that the as-prepared Cu O ball-in-ball hollow spheres were photostable during the photodegradation of Rh B.(2) Monodispersed Ag/Cu2 O composite with flower-like hierarchical micro-/nanostructures was synthesized for employed ethylene glycol(EG) as an organic solvent/additive and reductant. Most importantly, Ag+ ion plays an important role in mediating the formation of the flower-like hierarchical micro-/nanostructures. In the study of photocatalytic degradation of methyl orange, it was found the flower-like hierarchical structure Ag/Cu2 O composite exhibits a superior photocatalytic activity under visible light 40 min, and photocatalytic degradation rate reaches 98.97 %. Ag combines with Cu2 O to form the Ag-Cu2 O heterostructure. The heterostructure can effectively improve the separation of photogenerated electron-hole pairs, and thus enhance the photocatalytic acticity of the flower-like hierarchical structure Ag/Cu2 O composite. After recycling five times, the photocatalytic activity was not significantly reduced. In addition, such flower-like hierarchical structure Ag/Cu2 O composite can also serve as a potential photocatalyst for the degradation of Methyl Orange under visible light irradiation and in the presence of hydroxide water(H2O2). Compared with the catalyst without addition of hydrogen peroxide, the photodegradation time of methyl-orange can be shortened by half. The main reason was to accelerate the catalytic degradation time by adding of hydrogen peroxide to provide large amounts of ? OH and ? O2- promotes organic dye oxidation-reduction reaction occurs on the surface of catalyst to removal of organic pollutants. These results indicated that the hierarchical micro-/nano structure of Ag/Cu2 O composite has a good prospect for removing organic pollutants from waste water.