Preparation, Characterization And Gas-sensing Performance Of Tungsten Oxide Nanowires

Nitrogen oxides are one kind of typical air pollutants, which do great harm to theenvironment and human health. It is significant for practical demand that the researchand development of the high sensitive performance gas sensor and related gas-sensingmaterial for NO₂gas detection accurately and monitoring. Because of its specialstructural property, one-dimensional nanostructure tungsten oxides have became onekind of gas-sensing materials which have great development and application prospects.One-dimensional tungsten oxide nanowires gas-sensing material has been synthesizedby solvothermal method in my paper, and it is has been studied in detail that theinfluence of preparation condition and thermal annealing temperature formicro-morphology and microstructure, crystal phase and NO₂sensitive performanceof one-dimensional tungsten oxide nanowires.Tungsten oxide with different nanostructures has been synthesized under the200oC condition by the solvothermal method, with1-Propanol as the solvent, W₁₈O₄₉nanowires, WO3nanoplates and their composite structure have been synthesizedseparately by controlling the WCl6initial concentration. When cyclohexanol has beentaken as the reaction solvent, micron-beam structure has been formed because of therapidly growth of tungsten oxide. But too long reaction time will suppress the growthof nanowires in the length direction because of the formation of nanowire bundles.The test results of different nanostructure materials on gas-sensing property indicate:gas sensor based W₁₈O₄₉nanowires on NO₂gas-sensing property is relatively best, notonly displays the good reversibility, but also has the high sensitivity, fast response andrecovery character, its sensitivity can achieve123.6to the5ppm NO₂under the200oCoperating temperature, and its response and recovery time respectively is15s and112s.Annealing treatment changes microstructure of nanowire bundles and improvesremarkably gas-sensing property of naiowires. After annealing temperature surpassed400oC, the crystal phase of nanowires transformed from monocline W₁₈O₄₉tomonocline WO3. Under450oC annealing temperature, nanowire bundles transformedone-dimensional sheet structure because of structure fusion among neighboringnanowires of the bundles. The test results of tungsten oxides under different annealingtemperature on gas sensing property indicate: tungsten oxide under450oC and550oCannealing temperature exhibit the extremely good selectivity for NO₂gas and thegreatly high sensitivity for NO₂gas with low concentration, when150oC, its sensitivity can achieve separately up to684.6and631to1ppm NO₂. Specially, underthe100oC optimum operating temperature, the sensitivity of one-dimensional sheetWO3which undergo450oC annealing treatment achieve up to835.9to1ppm NO₂.