Selectivity is an important parameter of resistive-type gas sensors that use metal oxides. In this study, a highly selective toluene sensor is prepared using highly dispersed gold-nanoparticle-loaded zinc oxide nanoparticles (Au-ZnO NPs). Au-ZnO NPs are synthesized by coprecipitation and calcination at 400 °C with Au loadings of 0.15, 0.5, and 1.5 mol %. The Au NPs on ZnO are about 2–4 nm in size, and exist in a metallic state. Porous gas-sensing layers are fabricated by screen printing. The responses of the sensor to 200 ppm hydrogen, 200 ppm carbon monoxide, 100 ppm ethanol, 100 ppm acetaldehyde, 100 ppm acetone, and 100 ppm toluene are evaluated at 377 °C in a dry atmosphere. The sensor response of 0.15 mol % Au-ZnO NPs to toluene is about 92, whereas its sensor responses to other combustible gases are less than 7. Such selective toluene detection is probably caused by the utilization efficiency of the gas-sensing layer. Gas diffusivity into the sensing layer of Au-ZnO NPs is lowered by the catalytic oxidation of combustible gases during their diffusion through the layer. The present approach is an effective way to improve the selectivity of resistive-type gas sensors.

中文翻译：

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超选择性甲苯-气体传感器：纳米级金负载在氧化锌纳米颗粒上

选择性是使用金属氧化物的电阻式气体传感器的重要参数。在这项研究中，使用高度分散的负载金纳米颗粒的氧化锌纳米颗粒（Au-ZnO NPs）制备了高度选择性的甲苯传感器。Au-ZnO NPs是通过在400°C下共沉淀和煅烧以0.15、0.5和1.5 mol％的Au负载量合成的。ZnO上的Au NP的大小约为2-4 nm，并以金属状态存在。多孔气敏层是通过丝网印刷制成的。在377℃的干燥气氛中评估传感器对200 ppm氢气，200 ppm一氧化碳，100 ppm乙醇，100 ppm乙醛，100 ppm丙酮和100 ppm甲苯的响应。0.15 mol％的Au-ZnO NPs对甲苯的传感器响应约为92，而其对其他可燃气体的传感器响应小于7。这种选择性的甲苯检测可能是由气敏层的利用效率引起的。在可燃气体扩散穿过Au-ZnO NPs传感层期间，其扩散到Au-ZnO NPs传感层中的气体的扩散率降低了。本方法是提高电阻型气体传感器的选择性的有效方法。