Fast and Selective Room-Temperature Ammonia Sensors Using Silver Nanocrystal-Functionalized Carbon Nanotubes

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• 作者：Shumao Cui ; Haihui Pu ; Ganhua Lu ; Zhenhai Wen ; Eric C. Mattson ; Carol Hirschmugl ; Marija Gajdardziska-Josifovska ; Michael Weinert ; Junhong Chen
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2012
• 出版时间：September 26, 2012
• 年：2012
• 卷：4
• 期：9
• 页码：4898-4904
• 全文大小：347K
• 年卷期：v.4,no.9(September 26, 2012)
• ISSN：1944-8252

文摘

We report a selective, room-temperature NH₃ gas-sensing platform with enhanced sensitivity, superfast response and recovery, and good stability, using Ag nanocrystal-functionalized multiwalled carbon nanotubes (Ag NC鈥揗WCNTs). Ag NCs were synthesized by a simple mini-arc plasma method and directly assembled on MWCNTs using an electrostatic force-directed assembly process. The nanotubes were assembled onto gold electrodes with both ends in Ohmic contact. The addition of Ag NCs on MWCNTs resulted in dramatically improved sensitivity toward NH₃. Upon exposure to 1% NH₃ at room temperature, Ag NC鈥揗WCNTs showed enhanced sensitivity (9%), very fast response (7 s), and full recovery within several minutes in air. Through density functional theory calculations, we found that the fully oxidized Ag surface plays a critical role in the sensor response. Ammonia molecules are adsorbed at Ag hollow sites on the AgO surface with H pointing toward Ag. A net charge transfer from NH₃ to the Ag NC鈥揗WCNTs hybrid leads to the conductance change in the hybrid.

Keywords:

ammonia gas sensor; nanohybrid; silver nanocrystal; carbon nanotube; high performance; room-temperature