Ultrafine Tungsten Oxide Nanowires: Synthesis and Highly Selective Acetone Sensing and Mechanism Analysis

By using WCl₆ as a precursor and absolute ethanol as a solvent, ultrafine W₁₈O₄₉ nanowires (UFNWs) were synthesized by a one-pot solution-phase method and used as gas sensing materials. Their crystal structure, morphology, and specific surface area can be regulated by controlling precisely the content of the WCl₆ precursor in the solution. It has been found that, when the content of the precursor is 4 mg/mL, the formed products are UFNWs with a diameter of about 0.8 nm, only one crystal plane [010] is exposed, and the specific surface area is 194.72 m²/g. After the gas sensing test, we found that they have excellent selectivity to acetone. The response of 50 ppm acetone reaches 48.6, the response and recovery times are 11 and 13 s, respectively. In order to evaluate the interaction between W₁₈O₄₉ surfaces and different volatile organic compound (VOC) molecules, we simulated and calculated the adsorption energy (E_Ads) among different W₁₈O₄₉ surfaces and different VOCs by DFT. The calculated results are in agreement with the experimental results, further confirming the ultrahigh selectivity of W₁₈O₄₉ UFNWs to acetone. The above results demonstrate that the high selectivity of W₁₈O₄₉ UFNWs to acetone is due to the exposure of its single crystal plane [010]. This work has practical significance for better detection of acetone.