Preparation Of Titanium Dioxide Hollow Nanospheres And Their Catalytic Applications

With the continuous development of the global economy,environmental issues have become more and more serious,and environmental and energy issues have become two major issues faced by the sustainable development of human society.The catalytic technology using nano-materials as a catalyst provides an effective way for us to effectively prevent pollution and control the environment.Therefore,the synthesis and application of nanomaterials has always been a hot topic in the fields of materials science,chemistry,physics,and life sciences.Titanium dioxide,as one of the most common nanomaterials,has many advantages,such as:low cost,simple preparation,high catalytic activity,chemical stability,resistance to acid and alkali and chemical corrosion,and its own non-toxic and harmless,so there are more studies on titanium dioxide.However,because titanium dioxide has a large bandgap width,the photoresponse range is in the ultraviolet region,which makes its use of sunlight less efficient.At the same time,titanium dioxide is prone to recombination of photogenerated electrons and holes in the process of light excitation,which seriously affects its light.Catalytic efficiency.Therefore,how to use sunlight more effectively and enhance the activity of titanium dioxide photocatalyst is the focus of current photocatalysis research and research frontier.In this paper,titanium dioxide hollow nanospheres particles were prepared by hydrothermal method,and then modified by noble metal loading.The catalytic applications of the modified two kinds of composite catalysts were explored.The full text is divided into four chapters,including the following:The first chapter is literature review,mainly introduces the research status,synthesis and modification methods of nano-titanium dioxide and its main application fields.The second chapter describes a method of preparing titanium dioxide hollow nanospheres by hydrothermal method.The method mainly includes two steps:（1）Using anhydrous ethanol as solvent and tetraisopropyl titanate as raw materials,using precursor method to synthesize precursors.（2）Titanium dioxide nanospheres with different hollow structures were synthesized by hydrothermal method under alkaline conditions by controlling different hydrothermal times.The influence of the type and amount of salt,the concentration of sodium hydroxide,the hydrothermal temperature,the hydrothermal time,and the calcining temperature on the structure of titanium dioxide microspheres was investigated.The X-ray diffraction（XRD）analysis,transmission electron microscopy（TEM）and nitrogen adsorption-desorption were investigated.The measurements were performed to characterize the results.The results show that with the increase of the hydrothermal time,titanium dioxide gradually transitions from a solid structure to a hollow structure.The longer the hydrothermal time is,the more obvious is the hollow structure.In the third chapter,Pd/TiO₂ composite catalysts was prepared by impregnation method on titanium dioxide surface loaded with noble metal Pd,and the catalytic effect of the catalyst on Suzuki coupling reaction under normal temperature and pressure conditions was explored.The reaction product was analyzed by gas chromatography.The results show that the catalytic activity of this catalyst is high under normal temperature and pressure conditions.Compared with the traditional Suzuki reaction,the catalyst synthesized in this experiment is not only has a good catalytic effect,and more energy-efficient and environmentally friendly.In the fourth chapter,Pt/TiO₂ composite catalysts was prepared by impregnation method on titanium dioxide surface loaded with noble metal Pt,and the catalytic effect of this catalyst in the oxidation of benzyl alcohol under visible light illumination was explored.The reaction product was analyzed by gas chromatography.The results show that the catalyst has good catalytic effect on benzyl alcohol oxidation under visible light illumination,and the selectivity to benzaldehyde of the target product reaches 100%.This experiment provides a great reference for the full use of solar energy.