Research On The Preparation And Application Of Hierarchical Dual-porous Structured TiO₂-Au Supported Photocatalysts

As a green technology with mild reaction conditions,fast reaction speed,low energy consumption and wide application range,semiconductor heterogeneous photocatalysis technology has been widely used in the fields of environmental protection and energy development,among which photocatalytic degradation of organic pollutants has gradually become one of the research hotspots in the field of environmental protection.Nano-titanium dioxide is a commonly used photocatalyst because of its good optical properties.However,its low visible light absorption capacity and high photogenerated hole-electron pair recombination efficiency lead to its low utilization of solar energy.In addition,there will be a serious agglomeration phenomenon among the nano-titanium dioxide particles,resulting in the reduction of specific surface area,the number of active sites and catalytic efficiency.Moreover,the nano-titanium dioxide has the problem of being difficult to recycle.Therefore,in order to realize the efficient and recyclable photocatalytic application of photocatalysts,a new supported noble metal-titanium dioxide composite photocatalyst combining carrier support and noble metal modification was designed and synthesized,it was applied to visible light catalytic degradation of the organic dye rhodamine B.The details are as follows:?1?Exploration and optimization of the preparation conditions of hierarchical dual-porous structured titanium dioxide-gold?TiO₂-Au?supported photocatalyst.The organic phase controlled assembly of nano-sized titanium dioxide particles was carried out in the channels of the mesoporous silica template by thiol-metal coordination,which can effectively combine the high loading of nano-sized titanium dioxide with the good permeability of the carrier.Then,the way of ligand substitution improved the water solubility of the assembly.The in-situ generation of gold nanoparticles achieved effective contact and uniform loading of gold nanoparticles and nano-sized titanium dioxide in the channels of the assembly.Finally,a composite photocatalyst with a hierarchical dual-porous structure was prepared through the coating and calcination of the mesoporous silica layer.Exploring and optimizing the preparation conditions of the catalyst is conducive to achieving high loading of titanium dioxide-gold nano-units in the composite catalyst,while retaining the unique central radial structure of dendritic mesoporous silica template,which makes it have high permeability and more active sites,so as to improve its catalytic activity and recycling efficiency.?2?Characterization and catalytic performance of the hierarchical dual-porous structured TiO₂-Au photocatalyst.The structural morphology and colloidal properties of the catalyst were characterized,which was used to describe the changes in morphology,pore structure,hydrophobicity,surface ligands,particle size and Zeta potential during the preparation process.Then the photoelectric performance of the catalyst was tested to study the chemical valence of the element,the separation and migration performance of photogenerated charge carriers.Subsequently,the catalyst was applied to the visible light catalytic degradation of the organic dye Rhodamine B.The research results show that the catalyst has excellent visible light catalytic degradation and recycling performance.Finally,the visible light catalytic degradation mechanism of the catalyst was discussed,and the active groups that play a major role in the degradation process were explored.