钒掺杂W18O49纳米线的室温p型电导与NO2敏感性能

钨氧化物纳米线在高灵敏度低功耗气体传感器中极具应用潜力, 且通过掺杂改性可进一步显著改善其敏感性能. 本文以WCl₆为钨源, NH₄VO₃为掺杂剂, 采用溶剂热法合成了钒掺杂的W₁₈O₄₉纳米线. 利用扫描电镜、透射电镜、X射线衍射、X射线光电子能谱仪表征了纳米线的微结构, 并利用静态气敏性能测试系统评价了掺杂纳米线的NO₂敏感性能. 研究结果表明: 五价钒离子受主掺杂进入氧化钨晶格结构, 抑制了纳米线沿轴向的生长并导致了纳米线束的二次集聚; 室温下, 钒掺杂W₁₈O₄₉纳米线接触NO₂气体后表现出反常的p型响应特性; 随工作温度逐渐升高至约110 ℃时, 发生从p型到n型的电导特性转变; 该掺杂纳米线气敏元件对浓度低至80 ppb (1 ppb=10^-9) 的NO₂气体具有明显的室温敏感响应和良好的响应稳定性. 分析并探讨了钒掺杂W₁₈O₄₉纳米线的高室温敏感特性及其p-n电导转型机理, 认为钒掺杂W₁₈O₄₉纳米线在室温下的良好敏感响应及反常p型导电性与掺杂纳米线表面高密度非稳表面态诱导的低温气体强吸附有关.关键词：氧化钨纳米线气体传感器室温灵敏度

P-type conductivity and NO2 sensing properties for V-doped W18O49 nanowires at room temperature

Tungsten oxide nanowire has a great potential application to gas sensor with high sensitivity and low power consumption. Its gas-sensing properties can be greatly improved after doping the nanowires. In this paper, vanadium (V)-doped W₁₈O₄₉ nanowires are synthesized by solvothermal method, with WCl₆ serving as precursor and NH₄VO₃ as dopant. The microstructures of the pure and the doped nanowires are characterized by using SEM, TEM, XRD, and XPS techniques, and the NO₂-sensing properties are evaluated in a static gas-sensing measurement system. The obtained results indicate that the introduction of V dopant suppresses the growth of one-dimensional nanowires along their axis direction and causes the secondary assembly of nanowires bundles. At room temperature, the V-doped W₁₈O₄₉ nanowires show an abnormal p-type response characteristic upon being exposed to NO₂ gas, and a conductivity transition from p-to n-type occurs when operating temperature is raised to about 110 ℃. The doped nanowires-based sensor exhibits obvious sensitivity and good response stability to dilute NO₂ gas of 80 ppb at room temperature. The origin for the p-n conductivity transition and the high sensitivity at room temperature for the V-doped W₁₈O₄₉ nanowires are analyzed, and they can be attributed to the strong surface adsorption of oxygen and NO₂ molecules due to the large density of unstable surface states.
Keywords：tungsten oxidenanowiresgas sensorroom temperature sensitivity