The Study Of Preparation And Photocatalytic Of Compound Nanomaterials TiO₂/Fe₂O₃ And TiO₂/SnO₂

Although nanometer TiO₂ has considered the most promising photocatalyst,it can only absorb less than 387 nm light because its band gap reaches 3.2 eV;and the life expectancy of those excited electron-hole is very short.These two fatal defects limited the scope of application.Thence, the primary problem of current research is to modify the TiO₂ to improve the performance of its optical absorption and optical quantum efficiency. Among them,the study hotspot is to adopt different oxides to form composite semiconductor,this way could effective enhance its photocatalytic activity.Used peptization-hydrothermal crystallization method,this paper prepared composite nanometer catalyst of TiO₂/Fe₂O₃、TiO₂/SnO₂.At first, through research-based nano-composite catalyst TiO₂/Fe₂O₃ crystal structure,particle images,UV-Vis absorption performance,photocatalytic and the energy band structure between TiO₂ and Fe₂O₃,Analysis showed that:The energy band of these two oxides in the composite photocatalyst must be met the principle of energy band,which means the valence band and conduction band charged potential of modified oxide higher than TiO₂.Based on peptization-hydrothermal crystallization method,the paper used three ways to prepare composite TiO₂/SnO₂ samples,and researched crystalline structure,particle images,UV-vis absorption performance of composite samples based on these analytical instrument:XRD,SEM, UV-vis.Then,this paper researched the photocatalytic activity of TiO₂/SnO₂ used the means of degrading methyl orange.The study shows that:①A-TiO₂/SnO₂ is continuous replacement solid solution structure,which preparation is focuses on adding Sn⁴⁺.The TiO₂ form Rutile phase because of adding Sn⁴⁺,and with Sn⁴⁺content increasing, those various performances of solid solution converse to SnO₂ performances gradually,and the photocatalytic trend is reduced at first,and then increased.②The preparation of B-TiO₂/SnO₂ come from adding Sn（OH）₄.The crystal structure of TiO₂ is mixed phase of anatase and rutile in these products of TiO₂/SnO₂.Sn（OH）₄ play the same effect to the rutile phase conversion of TiO₂ as Sn⁴⁺.When the time of adding Sn（OH）₄ is postponed,the weight ratio of rutile phase-TiO₂ in the composite is decreased,and when the weight ratio of adding Sn（OH）₄ is increased,the weight ratio of rutile phase-TiO₂ is increased.③The preparation of C-TiO₂/SnO₂ come from adding SnO₂.The crystal structure of TiO₂ is anatase phase in these products of TiO₂/SnO₂.This paper investigated four factors-the heat treatment temperature of SnO₂,the quality ratio of SnO₂, peptization temperature and concentration of HNO₃,these factors play the important impact on the crystal structure,composite morphology,UV-vis absorption properties of compound Anatase-TiO₂/SnO₂.The best process parameter to photocatalytic activity:the heat treatment temperature of SnO₂ is 300℃,the weight proportion of SnO₂ is 40%, peptization temperature is 50℃and Nitrate concentration is 4mol/L.The compound TiO₂/SnO₂ samples reached 94.5%in the process of degrading methyl orange in 45 min,and increased 52.5%more than non-modified TiO₂.