Preparation Of Ordered Mesoporous TiO 2 And Modification Of Pore Wall Noble Metal And Photocatalytic Properties

Photocatalytic reaction can effectively reduce heavy metal ions with high valence state,mineralize organic pollutants,sterilize,and produce hydrogen via water splitting.Now,it has become one of the most hot research topics in environmental purification and dean-energy production.As a traditional photocatalyst,TiO₂ possesses fascinating features like good chemical stability,low cost and non-toxity.However,Ti O₂ can only be activated by UV lights because of the large energy band gap of 3.2 eV.Meanwhile,high recombination rate of electron-hole pairs and low quantum efficiency limit its practical applications.This work focuses on the studies of the preparation and photocatalytic performances of TiO₂ nanomaterials with different mesoporous structures.Meanwhile,the mesoporous TiO₂ photocatalysts doped by noble metal nanopartticles embedded in the walls are also synthesized and their photocatalytic behaviors are investigated.The effects of the morphology,the structure and the modification on the photocatalytic efficiencies in mineralization of organic pollutants and photocatalytic hydrogen production are explored.The follows are the details.（1）We have prepared well-ordered mesoporous TiO₂ photocatalysts by evaporation-induced self-assembly（EISA）method.By controlling the relative humidity of the atmosphere,we can talior the 3D cubic Im3 m,2D hexagonal p6 m and their mixed mesostructures with high surface area.The TiO₂ with mixed mesostructures shows the highest photocatalytic activity in degradation of phenol under UV light-rradiation.（2）We have prepared well-ordered mesoporous TiO₂ with Au nanoparticles（NPs）embedded in the TiO₂ walls by EISA method（Au/TiO₂）.By controlling the relative humidity of the atmosphere,we can talior the 3D cubic Im3 m,2D hexagonal p6 m and their mixed mesostructure.The main active species are determined as holes and hydroxyl radicals in photocatalytic degradation of phenol under visble lights irradiation.The 2D hexagonal mesoporous Au/TiO₂ exhibits the highest activity due to the stronger surface plasmon resonance from Au nanoparticles.（3）We have prepared well-ordered mesoporous Pt/TiO₂ by EISA method.By controlling the relative humidity of the atmosphere,we can obtain 3D cubic Im3 m,2D hexagonal p6 m and their mixed mesostructure.It is found that the 0.5 mol% Pt/TiO₂ photocatalyst exhibits the highest activity in hydrogen production from water-splitting.Meanwhile,the hydrogen production activity decreases with the increasing size of the sacrificial agent molecule due to increased mass transfer resistance.