Microwave Synthesis And Photocatalytic Activity Of One-dimensional Ceo₂ Nanomaterials

As a new functional material, CeO₂ nanomaterial are widely used to control of automobile tail gas, deal with polluted water, ultraviolet ray absorbefacient, polishing powder, electrochemistry, and glass clarify agent. For this, CeO₂ nanomaterial has a huge market with big potential and broad prospects. Material experts have been trying to reasearch and develop CeO₂ nanomaterial with good properties because of its potential development.Recently, one-dimensional nanostructure such as nanorod, nanobelt and nanotube is a topic of current interest for all the materials scientists around the world.The structure are believed to be a link in building nanodevice. So it is significant for synthesis of one-dimensional nanomaterial of CeO₂ with a simple and easy control method. This paper aims at the hot topic in the research world, selected affordable cerous nitrate and urea as raw materials, under the method of microwave homogeneous precipitation and obtained CeO₂ nanobelt and nanorod stucture. The productions were characterized by SEM, TEM, Laser size diffraction, X-ray diffraction, IR, UV-vis spectrum and BET.First, CeO₂ nanobelts were prepared using PEG4000. The results show that PEG4000 has an important influence in the synthesis of nanobelt CeO₂.Second, CeO₂ nanorods were obtained through tuning the concentration ratio of cerium nitrate and urea without PEG4000, and the influence of concentration ratio, the concentration of the raw materials, microwave reaction parameters and the sorts of solvent was discussed. The process of the self-assembly was roughly studied by TEM, and the evolving mechanism of one-dimensional CeO₂ nanostructure was explored. The TEM results shows that the formation of rodlike CeO₂ is: grains under the effect of hydroxy through the combine of lattice plane, following the regular pattern of the unite orientated growth along the grain growth direction, assemble to chain structure, and transversally connect to nanorod bundles step by step due to the hydrogen bonds. The photocatalytic activity of one-dimensional CeO₂ nanomaterial was evaluated by degradation of methyl orange. The experiment of photocatalytic activity reveals that the one-dimensional CeO₂ nanomaterial photocatalysts possess better degradation rate on methyl orange than P25, the best is CeO₂ nanorod. The factors affecting the methylorange degradation rate, such as different preparation methods of CeO₂, calcining system, catalyst amounts and pH value, were studied. The results indicate that:(1) The grain size is a prominent factor for catalyst efficiency. Generally speaking, catalytic effect is much more obvious with the particle size decreasing.(2) From the obtained nanorod CeO₂ at different calcinate temperatures as catalyst in degradation of methyl orange, we found that the effect of CeO₂ annealed at 300℃in air is the best. When calcining at 300℃, the effect of CeO₂ annealed in air is superior to that in N2, and the degradation rate of the former is more than three times than the latter.(3) The dosage of the catalyst should be proper, so that the light source and catalyst could be rational used of, and avoid extravagance.(4) In addition, the effect of catalyst is different in different pH value. It can be gained the best effect when the pH value is 5.