Preparation And Gas Sensing Properties Of TiO₂-based Nanofibers

This paper was prepared pure and doped TiO2nanofibers mainly byelectrospinning technology and explored internal doping and surface modificationeffect on gas sensing performance. The specific research contents mainly as thefollowing:1. The pure and doped TiO2nanofibers were prepared by electrospinningtechnology, we did a series of research to find out what is the main factors thatinfluences the electrospinning process, and how it brings influence on the process,including: PVP, Titanium butoxide, voltage, the sintering temperature, finally wegot the optimal parameters for electrospinning. TiO2nanofibers prepared byelectrospinning method is a kind of1-D nanostructure with rough surfaces andgood crystallinity. The sensors based on TiO2nanofibers respond to ethanol vaporand acetone vapor. The sensing mechanism of TiO2nanofibres was interpretedwith the surface carrier depletion model or the carrier transferring model.2. There have studied the effects of different elements and different doping onthe morphology, structure and gas sensing properties of TiO2nanofibers. It wasgiven the possible explanations for the improvement of gas sensing performance.From the SEM image, we found pure and doped TiO2nanofibers is basicallysimilar, both continuous nanofiber, with rough surface. Since the dopingconcentrations is less, it was no found the diffraction peak of the impurity elementor the impurity element oxides from the XRD pattern. When the concentration ofNi is1at.%，the sensor behaves good gas sensing and selectivity to H2S gas, withreducing the working temperature; When the concentration of Sn reaches to3at.%,the sensor possess good gas sensing character and good selectivity to toluene, withreducing the working temperature, fast response and recovery time; The TiO2sensor shows fine sensibility for H2S gas when the composition of the doped Ag is1at.%Co-doped TiO2nanofibers show excellent sensitivity to CH4gas.3. Ag surface modified TiO2nanofibers and Ag surface modified TN nanofibers(1at.%Ni doped TiO2nanofibers) were synthesized on the surface ofTiO2nanofibers and TN nanofibers by photocatalytic reduction method, and thegas sensing property of the Ag surface modified TiO2nanofibers and Ag surfacemodified TN nanofibers were also studied. Compared with the pure and dopedTiO2nanofibres, Ag surface modified TiO2nanofibers behaves better gas sensingto H2S gas. It can be achieved optimal Ag surface modified TN nanofibers for thegas sensing performance by adjusting the UV irradiation time. The Ag surfacemodified TN nanofibers greatly enhanced the sensitivity and selectivity to H2S gas,while also reducing operating temperature. It was used to interpret theimprovement of gas sensing property of Ag surface modified TiO2nanofibers andAg surface modified TN nanofibers with the chemical interaction mechanism. Onone hand, Ag metal nanoparticles act as the absorption center of oxygen, which;on the other hand, Ag metal nanoparticles favor the absorption of one kind ofreducing gas molecules on the surface of nanofibers, and catalyze the reactionbetween such molecules and absorbed oxygen.