Preparation And Gas Sensing Properties Of Titania Nanotube Arrays

It is believed that the miniaturization, integration and multi-function will be the development trends in gas sensor. One dimension nano materials have promising applications in gas sensing field due to their high surface-to-volume ratio and special chemical activity. Titania nanotube arrays were fabricated and the sensing propertise to acetone and hydrogen were studied in this paper.Titania nanotubes were grown on the top of pure titanium sheets in the F- containing electrolyte using electrochemical anodizaion method. The fabrication conditions were studied and the aim to precisely control the nanotube arrays dimensions was achieved. XRD and FESEM were employed to analyze the phase state and surface morphologies of the samples. The results revealed that the as prepared samples are amorphous, and both anatase and rutile phases of titania are present after heat treatment. Voltage and reaction time are the key factors that determine the surface morphologies of the titania nanotube arrays and the influence of electrolyte concentration and electrode distance can be negligible. The samples with length up to several micrometer were prepared through optimizing experiment conditions. A mechanism of titania nanotube arrays formation was illuminated.Gas sensing properties of the samples were studied. The titania nanotubes prepared in 1M HNO₃+1M NaOH+0.5wt% HF electrolyte under 20 voltage for 2 h showed appreciable sensitivity towards acetone vapor at temperatures as low as 150℃. The sensitivy increased to 269 and the response time decreased to 23s at 350℃. Test temperature and gas concentration are the key factors that influence the sensing properties. The titania nanotubes also show good sensitivity to hydrogen. The sensor has long response and recover time when the Pt electrode was replaced by Al. The sensing mechanism was analyzed based on absorption theory.This study broadens the range of application filed of one dimension nano materials and paves the way for the further research.