NH3 interaction with catalytically modified nano-WO3 powders for gas sensing applications
NH3 interaction with catalytically modified nano-WO3 powders for gas sensing applications
复制标题
NH3 与催化改性纳米氧化物粉末的相互作用，用于气体传感应用
DOI：
10.1149/1.1556055
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发表时间：
2003-04-01
影响因子：
3.9
通讯作者：
Morante, JR
中科院分区：
文献类型：
--
作者：
Jiménez, I;Centeno, MA;Morante, JR
详细分析了用于氨气检测的纯WO_3和添加了铜、钒等催化添加剂的纳米WO_3粉末。材料在两种不同的温度(400℃和700℃)下进行了热处理，并引入了两种不同浓度的催化添加剂(0.2%和2%)，以研究这些WO_3基材料的气敏性能。晶体结构表征表明，在所分析的材料中存在三斜和单斜晶系的混合结构。加法表征表明，催化金属以阳离子形式存在于基质晶格中。基于纯WO_3的厚膜气体传感器表现出异常的传感器响应，这归因于氨氧化为NO的复杂过程。另一方面，催化WO_3基气体传感器具有更直接、更简单的传感器响应。用漫反射红外光谱研究了氨与WO_3的相互作用。纯WO_3显示出W=O泛音带减少和一些亚硝化带。在这种情况下，NH3会与末端W=O键的表面氧反应，从而导致NO的生成。催化WO_3避免了这一反应，从而避免了NH3的非选择性催化氧化，提高了传感器的响应速度。讨论了引入的添加剂对氨氧化的影响，从而对传感器响应的影响。(C)2003年电化学会。
Nanocrystalline powders of WO3, pure and with catalytic additives such as copper and vanadium, for ammonia gas detection are analyzed in detail. Material was annealed at two different temperatures (400 and 700degreesC) and catalytic additives were introduced in two different concentrations (0.2 and 2%) in order to study the gas sensor performances of these WO3-based materials. Crystalline structure characterization shows that a mixture of triclinic and monoclinic structure was present in the materials analyzed. Additive characterization reveals that catalytic metals were located as cations in the matrix lattice. Thick-film gas sensors based on pure WO3 show an abnormal sensor response, which is attributed to a complex process originated by the oxidation of ammonia to NO. On the other hand, catalyzed WO3-based gas sensors show a more direct and simple sensor response. Interaction of ammonia with WO3 was studied by diffuse reflectance infrared spectroscopy. Only pure WO3 presented a W=O overtone band decrease and some nitrosil bands. In this case, NH3 would react with the surface oxygen of terminal W=O bonds and would lead to the formation of NO. Catalyzed WO3 avoided this reaction and so the unselective catalytic oxidation of NH3, improving sensor response. Influence of introduced additives on ammonia oxidation and thus on sensor response is discussed. (C) 2003 The Electrochemical Society.