Preparation And Gas Sensing Properties Study On One-dimensional VO_x Nanomaterial Arrays

As the rapid expansion of industrialization and technology, people begin to pay more and more attention to the problems of environmental contamination and safety in production. Gas sensors play an irreplaceable role in environmental monitoring, military and high-tech area. In recent years, people paid their attention to nanomaterial, which is a hotspot research area, to improve the performance of gas sensors. Nanomaterial have some exceptional performances such as small size effect and surface effect, these exceptional performances make it possible to break through the performance of traditional bulk material. Vanadium oxides crystallise in a layered structure and have strongly anisotropic physical properties. The unique physical and chemical properties are widely applied to the fields such as thermochromism, electrochromism, optics and electrochemistry. Gas sensors based on vanadium pentoxide have attracted more and more attentions in recent years.We researched the synthesis method of one-dimensional vanadium oxides nanomaterial arrays, discussed the preparation of gas sensors based on one-dimensional vanadium oxides nanomaterial arrays and tested the gas sensing property of such sensors. The main conclusions are as follow:(1) The templates used for this study were radiation-etched hydrophilic PC membrane with pore diameters of200nm and thickness of10μm. Vanadium pentoxide sol was deposited into the holes of PC template, the process of electrophoresis could be divided into three stages. After that, PC template was burned up by heat treating, the vanadium oxides nanorods were crystallized and reinforced in this process.(2) X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ultraviolet visible spectrometer (UV-Vis) were used to characterize the morphology and structural characteristics, the results are as fllow:vanadium oxides sol was deposited into the holes of PC template randomly and had not crystallized yet. V2O5crystals grew along (600), the other crystals such as V2O5in (300) and V2O5-3H2O in (600) stopped grow and minority of them were distributed around the V2O5nanorods in (600). We can also estimate the forbidden bandwidth of the sample through the UV-Vis test, the forbidden bandwidth of the sample is about2.8eV, which is higher than that of bulk V2O5crystals with a forbidden bandwidth of2.24eV. The enhance of forbidden bandwidth could be attributed to the small size effect and surface effect of nanomaterials.(3) The gas sensing tests of one-dimensional vanadium oxides nanomaterial arrays show that, the sample exhibited apparent reaction to500ppm ethanol under a working temperature of180℃, however, the V2O5thin film showed no reaction to ethanol gas in the same condition. The V2O5thin film showed response to500ppm until the working temperature enhanced to250℃. The contrast of gas sensing performance indicate that, materials in nano scale have better gas sensing performance than that of bulk materials, they have higher sensitivity and need a lower working temperature.