Highly sensitive and selective hydrogen sulfide and toluene sensors using Pd functionalized WO3 nanofibers for potential diagnosis of halitosis and lung cancer
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- 作者：Nam-Hoon Kim ; Seon-Jin Choi ; Dae-Jin Yang ; Jihyun Bae ; Jongjin Park ; Il-Doo Kim
- 关键词：Electrospinning ; Catalyst ; Exhaled breath sensor ; Tungsten oxide ; Palladium
- 刊名：Sensors and Actuators B: Chemical
- 出版年：31 March, 2014
- 年：2014
- 卷：193
- 期：Complete
- 页码：574-581
- 全文大小：2731 K
文摘
In this work, we report a remarkably improved toluene response and superior cross-sensitivity against H2S molecules by combining Pd catalysts and highly porous WO3 nanofibers (NFs). We functionalized Pd catalysts inside and/or outside of WO3 NFs synthesized by electrospinning, which is a facile and versatile process for producing webs of metal oxide NFs. Pd-embedded WO3 NFs were obtained by the electrospinning of a Pd and W composite precursor/poly(methyl methacrylate) (PMMA) solution followed by calcination at 700 掳C. Pd nanoparticles (NPs) (6-10 nm) synthesized by a polyol method were decorated on the WO3 NFs (Pd-NPs/WO3 NFs) by the attachment of the Pd NPs on as-prepared WO3 NFs. The gas sensing characteristics of pure WO3, Pd-embedded WO3, Pd-NPs/WO3, and Pd-NPs/Pd-embedded WO3 NFs were tested using H2S and toluene gases in a highly humid atmosphere (RH 90%), which is similar to human exhaled breath. The results showed that the Pd-NPs/Pd-embedded WO3 NFs whose inner and outer layers were decorated by Pd catalysts, exhibited a high toluene response (Rair/Rgas = 5.5 at 1 ppm) and remarkable selectivity against H2S (Rair/Rgas = 1.36 at 1 ppm) at 350 掳C, whereas pristine WO3 NFs showed superior H2S response (Rair/Rgas = 11.1 at 1 ppm) along with a negligible response toward toluene (Rair/Rgas = 1.27 at 1 ppm). The highly porous WO3 NFs decorated with Pd catalysts, exhibited potential feasibility, i.e., a low limit of detection (LOD) of 20 ppb (Rair/Rgas = 1.32) at 350 掳C, for application in VOCs sensors, particularly for diagnoses of lung cancer.