Improvement Of The Photo-assisted Gas Sensitivity Of TiO₂ Semiconductor And The Corresponding Effect On Photocatalytic Performances

Metal oxide semiconductor materials has been paid extensive attention in the field of photo-assisted gas sensors and photocatalysis due to its photo response characteristics,and it is always the goal pursued by all to improve the photo-assisted gas sensing and photocatalytic performance of the semiconductor material.Moreover,due to electron transfers occurring in the processes of both photo-assisted gas sensing and photocatalysis,there may be a certain relationship between the two processes.Therefore,it is great significance to explore how to improve the photo-assisted gas sensing performance of semiconductor material,and investigate the influence of the photo-assisted gas sensitivity exerted on the photocatalytic behavior.In this paper,in order to investigate the photo-assisted gas sensitivity and photocatalytic performance,the mechanism of the gas sensing response in the view of electron transfer and the relationship among the above three,improving the conductivity of TiO₂ gas sensors have been studied by means of introducing conductive additives and exploring new preparation method.The specific research was carried out as follows:on the one hand,TiO₂ sensors modified by polyaniline?PANI?were prepared by an in-situ chemical oxidative polymerization method,which were tested the photo-assisted gas sensing performances to CO in N2 atmosphere under UV irradiation and the performance of the photocatalytic oxidation of CO.Based on the characterization of the modified TiO₂ and the comparative result of pure TiO₂,the mechanism of photo-assisted gas sensing and photocatalytic performance were preliminarily explored.On the other hand,TiO₂ film sensor was prepared by an in-situ method,and its photo-assisted gas sensing behavior to hydrogen,acetone and ethylene in N2 or air atmosphere under UV irradiation and the photo photocatalytic performance have been tested,which also compared with those of the composite TiO₂ film sensor prepared by drop-coating method.After testing the crystal phase structure,surface morphology,light absorption and electrochemical property of the TiO₂ film,it was expected to reveal the improved behavior of photo-assisted gas sensing and the corresponding effect on the photocatalytic performance over this TiO₂ film.Based on the above study,the main results and conclusions were concluded as follows:?1?Comparing with pure TiO₂,4wt%PANI/TiO₂ could enhance the photo-assisted sensing response to CO under UV irradiation,this may be due to an interaction between PANI and TiO₂ by forming electron transport channel which would be benefit for accepting electron from CO,resulting in the improved photo-assisted gas sensitivity.?2?PANI could promote the photocatalytic oxidization of CO over TiO₂ due to its enhanced electron transfer.?3?With respect to the drop-coating method,the anatase TiO₂ film prepared by in-situ method not only exhibited the better stability and repeatability of gas sensing to H2,acetone and ethylene both in N2 and air atmospheres,but also presented a higher photocatalytic performances.?4?There existed a somewhat relationship among the photo-assisted conductivity,gas sensitivity and photocatalytic performance over TiO₂ semi-conductor.This work shows that the photocatalyic oxidation performance of TiO₂ can be promoted by enhancing the photo-assisted gas sensitivity of TiO₂ semiconductor by means of adding the conductive additives and improving the preparation methods.This viewpoint maybe provides a new idea and approach for theory study and application of the photo-assisted gas sensing and photocatalyic performance of semiconductors.