Different nanostructured tungsten oxides synthesized by facile solvothermal route for chlorine gas sensing

By varying different solvents, WO3 nanoparticles, nanorods, and nanoflakes were synthesized via facile solvothermal processes without structure-directing agent. The as-prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption measurements. The effect of the polarity of organic solvents used in the synthesis procedure on the morphologies of as-synthesized WO3 materials was proposed. Gas sensors based on the synthesized products were fabricated and their gas sensing properties were tested towards a variety of target gases. The results indicated that the sensor based on WO3 nanoparticles exhibited excellent selectivity, better response and recovery behavior and much higher sensitivity toward Cl-2 compared to those based on WO3 nanorods, and nanoflakes, although three samples have similar specific surface areas. These characteristics are suggested to arise from good crystallinity and high concentration of oxygen vacancy on the surface of WO3 nanoparticles.