Research Of Synthesis And Photocatalytic Properties On ZnO Nanostructures

The toxic organic pollutant is a global problem, which may threat the living being’shealth; and it is also a prior concerned issue of the significant environmental problem to ourcounty’s strategy of sustainable development. So, research on the decomposition of thepoisonous organic pollutant has been paid a lot attention by researchers. ZnO nanomaterialis an important semiconductor for its similar bandwidth with TiO₂and its greatphotocatalysis performance. When ZnO is used as photocatalyst, under the irradiation of UVray, the ZnO can be inspired and then generate the pair of electron-hole which make theorganic pollutant oxide or reduce to the environmentally friendly inorganic substance, suchas H₂O and CO₂. Using ZnO nanomaterial in this way presents a new idea to solve theproblem of organic pollution.Firstly, this article develops a simple hydrothermal way of synthesizing ZnOnanostructures. ZnO nanorods have been synthesized at the first, and then ZnO microsphereshave also been fabricated using a simple citrate-assisted solution approach to make nanorodsbecome microspheres.Secondly, Methyl orange solution is used as photocatalytic target to test theperformance of photocatalytic activity of ZnO nanorods and microspheres. By modifying thegrowth conditions such as temperature, concentration of solution and growth time, theaffects of the growth condition on the surface morphologies of ZnO microspheres have beenanalyzed, and then the photocatalytic properties of different surface morphologies of ZnOmicrospheres have also been studied.Thirdly, the morphology and crystalline structure characterization of synthesizedsamples were carried out by X-ray diffraction, Sirion FEG scanning electron microscopy.The room-temperature photoluminescence （PL） spectrum was measured using a He–Cd laseras the excitation source （325nm）. The possible mechanisms have been suggested for the formation and photocatalytic performance of these microstructures.Compared with the photocatalytic performances of different surface morphologies ofZnO microspheres, some conclusions have been obtained as follows:（1） ZnO microsphere has better photocatalytic performance than that of nanorod.（2） By modifying the experimental conditions, different surface morphologies of ZnOmicrospheres have been obtained, and the size of the microsphere can be easily tuned byadjusting the experimental conditions.（3） The best growth condition of ZnO microsphere is that the temperature is90oC,concentration of zinc nitrate is0.002mol/L, concentration of sodium citrate is0.0025mol/Land thegrowth time is6hours. The results indicate that the smaller size of nanostructures hasbetter photocatalytic performance, which is corresponding to high surface-to-volume ratios.