Zinc Bearing Tungstate Zinc Gas Sensitive Material

Metal tungstates are a kind of important inorganic materials. They have good application prospects in optical fibers, scintillation materials, photoluminescent materials, humidity sensors, magnetic devices, microwave applications, catalysts and corrosion inhibitors. Among them, zinc tungstate nanometer material is a good photoluminescence, photocatalytic and gas sensitive material. However, pure zinc tungstate nanomaterials are less sensitive to hydrogen.

Researchers have found a platinum loaded tungstate nanomaterial and its application in the field of gas sensing. This kind of nano-material can improve the sensitivity of zinc tungstate in hydrogen. It is prepared according to the following steps:

（1）1mmol Na₂WO₄•2H₂O, 5.44 mmol CH₃COONa•3H₂O and 0.46g PVP were added into 15 ml solution and stirred to form a homogeneous and transparent solution. The solution was deionized aqueous solution of ethylene glycol, the volume ratio of ethylene glycol to deionized water was 14:1.

（2）The aqueous solution of Zn (CH₃COO)₂ with 15 mL concentration of 0.067 mol/L was dripped and dispersed uniformly by stirring. The solution was dripped in 35 minutes.

（3）The solution was transferred to a 60mL PTFE autoclave and heated to 180°C at 8°C/min from room temperature (20-25°C). The reaction lasted for 12 hours at 180°C. After the reaction was completed, the mixture was cooled to room temperature and centrifuged to obtain white precipitate, which was then separated by deionized water and anhydrous ethanol. After washing 8 times, the white precipitate was put into the drying box and dried at 60°C for 12 h to obtain zinc tungstate.

（4）At room temperature, the zinc tungstate obtained was evenly dispersed in 50ml of absolute ethanol (obtained suspension) and dissolved in nitrogen to remove oxygen. Under the protection of nitrogen, an aqueous solution of H2PtCl6 with a concentration of 2mol/L was dripped into absolute ethanol. The solution was reversed by ultraviolet light with a power of 200W and a peak of 360nm for 12 hours. The metal platinum should be reduced and in situ compounded with zinc tungstate, where the radiation distance is 7cm. After the reaction was finished, the mixture was centrifuged, white precipitated, washed seven times with deionized water and anhydrous ethanol, dried at 70°C for 18h to obtain the nanometer zinc platinum tungstate material.

The zinc tungstate nanocomposites are more dispersed, sensitive and environmentally compatible. For the detection of ethanol gas, the concentration of ethanol gas is as low as 100ppm. When the concentration of ethanol gas is 100-4000ppm, the sensitivity range of zinc platinum tungstate nanorods is 1.355-4.23 and zinc platinum tungstate nanoparticles is 1.64-4.77.

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