Bio-Templated Synthesis And Application Of Nanosheets-Assembled TiO₂ Architectures And Their Composites

There are many excellent optical and chemical properties of titanium dioxide?TiO₂?nanomaterials,which are widely used in photocatalysis,battery materials and various sensors.However,due to the shortcomings of TiO₂,such as wide band gap and poor conductivity,some practical applications of TiO₂ are limited.Aiming at these problems,this paper used bacteria as template and reactor to prepare nanosheets-assembled TiO₂architectures by simple sol-gel method,and also prepared different composites based on nanosheets-assembled TiO₂ architectures.What's more,the application of composites in photocatalytic degradation of rhodamine B,electrocatalytic oxidation of methanol and electrochemical detection of trace methyl parathion were studied.The main research contents of this paper are as follows:1.The nanosheets-assembled TiO₂ architectures were successfully synthesized by sol-gel method using different bacteria as biological templates,the formation process and growth mechanism of TiO₂ nanosheets and the effects of different calcination temperature and calcination atmosphere on morphology of nanosheets-assembled TiO₂ architectures were studied.It was found that both Gram-positive and negative bacteria could promote the synthesis of nanosheets-assembled TiO₂ architectures,and the size of the nanosheets was related to the amount of tetrabutyl titanate and water added.In addition,hollow porous TiO₂ microspheres?HP-TiO₂?could be obtained by calcination of nanosheets-assembled TiO₂ architectures in air at 750?,and carbon/TiO₂ nanosheets microspheres?C/TiO₂-NS?could be obtained by calcination at 750?in argon.2.The photocatalytic degradations of rhodamine B in TiO₂ microspheres with different conditions under ultraviolet light were investigated.Then,HP-TiO₂-MIL-101?Fe?composites were prepared by combining HP-TiO₂ with MIL-101?Fe?,after that their photocatalytic performance and bactericidal properties were studied.It was found that the degradation rate constant of rhodamine B degraded by HP-TiO₂ formed by calcination at750?was more than three times that of commercial P25.The degradation rate constant of HP-TiO₂-MIL-101?Fe?composites in visible light versus rhodamine B was 4.2 times that of MIL-101?Fe?and 90.9 times that of HP-TiO₂.Furthermore,the composites had the good reusability?6 times?,stability?placement for 20 days?and certain bactericidal performance.3.Hollow porous TiO₂ microspheres,carbon/TiO₂ nanosheets microspheres and their platinum composites were prepared,and electrocatalytic oxidation of methanol and direct electrochemical detection of methyl parathion were studied as well.In the study of electrocatalytic oxidation of methanol,it was found that the mass activity of electrocatalytic oxidation of methanol from HP-TiO₂-Pt,which was obtained by a GCE with HP-TiO₂ microspheres electrochemical deposited in chloroplatinic acid for 1 h,was more than 3 times that of commercial Pt/C,the CO tolerance ability?I_f/I_b?was twice that of commercial Pt/C;The mass activity of electrocatalytic oxidation of methanol and the CO tolerance ability from C/TiO₂-NS-Pt,which was obtained by a GCE with C/TiO₂-NS microspheres electrochemical deposited in chloroplatinic acid for 1 h,were 2 times and1.37 times that of commercial Pt/C catalysts,and both two composites had good stabilities.Furthermore,in the research of direct electrochemical detection of trace methyl parathion,HP-TiO₂ or C/TiO₂-NS microspheres was modified on GCE could detect the presence of trace methyl parathion sensitively.Moreover,the reduction peak signal in methyl parathion solution of C/TiO₂-NS is 4.79 times that of HP-TiO₂ material,which had a remarkable and efficient detection effect.