Study On Preparation And Photocatalytic Properties Of Mesoporous TiO₂/Go Composites Doped With The Rare Earth

TiO₂ is recognized as the most ideal light catalyst due to its high catalytic activity,nontoxic,cheap and so on,but its big band gap（3.2 eV）and optical excitation generated electron-hole recombination rate higher limit the practical application.The synthesis mesoporous structure can obtain the catalyst with larger surface area and higher catalytic activity,but the photocatalytic performance of mesoporous TiO₂ is still not obvious under the visible light.Graphene with the large specific surface area and the good electrical conductivity has caught people’s attention,and synthesis of graphene-TiO₂ composite material became a research hotspot in order to improve the photocatalytic performance of TiO₂,but its water solubility is poorer and it is a difficult problem that we try to prepare the graphene-TiO₂composite.Whereas,the graphene oxide（GO）which is prepared by the Hummers method contains hydroxyl,carboxyl,epoxy groups and some other polar groups.So these polar groups make GO easy to dissolve in water.The mesoporous TiO₂ catalys and the rare earth Nd³⁺doped mesoporous TiO₂photocatalytsts with high activity were prepared by the sol-gel and hydrothermal methods with the sodium dodecyl sulfate as the template agent,tetrabutyl titanate as the titanium source.Then a series of mesoporous TiO₂/GO composites and the rare earth Nd³⁺doped mesoporous TiO₂/GO composites were prepared.The obtain samples were characterized by XRD,pore structure analysis（BJH and BET）,SEM,TEM,XPS and UV-vis to reveal microstructure,morphology,valence of the element in sample surfaces and the spectroscopy properties.The methyl orange was used to simulate pollutant to test their photocatalytic activity under the ultraviolet light and the visible light.The experimental results are as follows:（1）Mesoporous TiO₂ photocatalysts which were prepared with the sodium dodecyl sulfate as the template agent at the different conditions are anatase phase.Their particle size and specific surface area are about 3-5 nm and 250 m²/g.The pore size distribution are uniform and mainly concentrated distribution between 10 to 50 nm.When the mesoporous TiO₂ catalyst was pepared with the n-butyl alcohol as solvent,the template agent content 38.1%and the hydrothermal crystallization time 28 h,its effect that the methyl orange is degradated under the ultraviolet light is best and can reach 97.7%in60 min.（2）Series of the rare earth Nd³⁺doped mesoporous TiO₂ photocatalysts have stronger photocatalytic properties than pure mesoporous TiO₂photocatalysts.The rare earth Nd³⁺can inhibit the mesoporous TiO₂photocatalysts reunion and decrease its grain size to a certain degree.Also it can increase mesoporous TiO₂ photocatalysts pore size and pore volume.The specific surface area of the rare earth Nd³⁺doped mesoporous TiO₂photocatalysts can reach 250 m²/g.（3）The mesoporous TiO₂/GO composites and the rare earth Nd³⁺-mesoporous TiO₂/GO composites have high catalytic properties under the visible light.The good synergistic effect of the rare earth Nd³⁺and GO can better inhibit the TiO₂ reunion and make the grain size evenly dispersed in the interlayer.The good synergistic effect also broaden the light response range.The composite photocatalyst pepared with the doped Nd³⁺1.5%and the GO10%has better catalytic performance under the visible light and the degradation rate can reach 82.6%in 120 min with the methyl orange as the simulated pollutants.（4）The mesoporous TiO₂ photocatalysts and GO/TiO₂ composite photocatalysts prepared with the sodium dodecyl sulfonic acid and the citric acid as the double template agent can further improve the mesoporous TiO₂catalytic properties under the visible light.The sample 45CA-TiO₂/GO-0.5photocatalyst degrades methyl orange under the visible light irradiation,and the degradation rate can reache 100%in 60 min.