Fabrication Of TiO₂ And MoO₃ Nanowires Based Sensor

One dimesional nanostructure and heteronanostructure of metal nanoparticle on nanowire have shown great potential application in the area of biosensor and gas sensor. So far, many sensors based on nanowires have been investigated and reported. In this paper, TiO₂ nanowire biosensor to detect the enteropathogenic E.Coli with high sensitivity has been developed successfully. In addition, gas sensor based on noble metal Ag nanoparticles decorated MoO₃ and TiO₂ nanowire working at room temperature was fabricated successfully.1. Nano-biosensor with excellent selectivity and high sensitivity has been developed successfully based on the sensitivity of TiO₂ nanowire to detect the enteropathogenic E.Coli. Based on the specific interaction between antibody and bacteria, the charge transfer on the TiO₂ nanowire surface caused by the antibody immobilization and capture of the bacteria can be detected sensitively by the electrochemical impedance spectroscopy. The detecting time of the biosensor to enteropathogenic E.Coli is only about 50 min, and the detection limit can be down to about 102 cfu/mL. Besides, the concentration of enteropathogenic E.Coli can be determined by the changes of impedance, when the antibody on the surface of TiO₂ nanowire captures the enteropathogenic E.Coli.2. Heteronanostructures of Ag nanoparticles on MoO₃ nanowires were synthesized by a simple and simultaneous redox method at room temperature. The synthesis integrated four different synthetic reactions, including the oxidation of [Na(H₂O)₂]0.25MoO₃ layered bronze, the reduction of silver ions, the in situ simultaneous growths of the self-organized Ag nanoparticles and the MoO₃ nanofibers. The size and distribution density of Ag nanoparticles on MoO₃ nanowires can be easily controlled by adjusting the concentration of AgNO₃ solution in the reaction. Then the sensing properties toward H₂ and O₂ of this nanoparticles decorated nanowires based sensor were investigated at room temperature. The experimental results show that this nanowires based gas sensor has good sensitivity toward 400 ppm H₂ and 1000 ppm O₂ at room temperature, respectively.3. TiO₂ nanowires modified by Ag nanoparticles with uniform sizes of Ag nanoparticles were prepared by a simple redox reaction based on the TiO₂ nanowires prepared by hydrothermal reaction. Ag nanoparticles functionalizing TiO₂ nanowires with different sizes and distribution densities of Ag nanoparticles can be easily obtained by controlling the concentration of AgNO₃ solution in the reaction. Then the gas sensor based on the nanowires sensing materials was fabricated. The nanowires based gas sensor show good sensitivity toward 500 ppm H₂ and 1000 ppm O₂ at room temperature, respectively. Besides, the flower-like CoS nanostructures were prepared by a simple hydrothermal synthesis approach. The formation mechanisms and the electrochemical properties were also investigated.