Room temperature NO2-sensing properties of WO3 nanoparticles/porous silicon

WO 3 nanoparticles were synthesized by sol–gel method with tungsten hexachloride (WCl 6 ) as precursor and deposited onto porous silicon and alumina substrates by dip-coating. The morphology and crystal structure of samples were investigated by means of field emission scanning electron microscope and X-ray diffractometer. It is the experimental results demonstrated by gas sensing tests that WO 3 nanoparticles combining with the substrate of porous silicon presented an improved NO 2 -sensing property at room temperature. Compared to WO 3 deposited on alumina working above 100   °C, the WO 3 nanoparticles/porous silicon exhibited higher properties upon exposure to sub-ppm concentrations of NO 2 gas at room temperature. Additionally, the NO 2 -sensing performance of WO 3 nanoparticles/porous silicon was enhanced markedly, in comparison to pure porous silicon. The mechanism of WO 3 /porous silicon composite structure on the NO 2 sensing was explained in detail.