Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
J Am Chem Soc. 2013 Feb 13;135(6):2306-12. doi: 10.1021/ja310844u. Epub 2013 Feb 4.
Atom-thick materials such as single-walled carbon nanotubes (SWCNTs) and graphene exhibit ultrahigh sensitivity to chemical perturbation partly because all of the constituent atoms are surface atoms. However, low selectivity due to nonspecific binding on the graphitic surface is a challenging issue to many applications including chemical sensing. Here, we demonstrated simultaneous attainment of high sensitivity and selectivity in thin-film field effect transistors (TFTs) based on outer-wall selectively functionalized double-walled carbon nanotubes (DWCNTs). With carboxylic acid functionalized DWCNT TFTs, we obtained excellent gate modulation (on/off ratio as high as 4000) with relatively high ON currents at a CNT areal density as low as 35 ng/cm(2). The devices displayed an NH(3) sensitivity of 60 nM (or ~1 ppb), which is comparable to small molecule aqueous solution detection using state-of-the-art SWCNT TFT sensors while concomitantly achieving 6000 times higher chemical selectivity toward a variety of amine-containing analyte molecules over that of other small molecules. These results highlight the potential of using covalently functionalized double-walled carbon nanotubes for simultaneous ultrahigh selective and sensitive detection of chemicals and illustrate some of the structural advantages of this double-wall materials strategy to nanoelectronics.
原子层厚度的材料，如单壁碳纳米管（SWCNTs）和石墨烯，对化学干扰表现出超高的灵敏度，部分原因是所有组成原子都是表面原子。然而，由于在石墨表面上的非特异性结合，导致选择性低，这是许多应用（包括化学传感）面临的一个挑战。在这里，我们展示了在外壁选择性功能化的双壁碳纳米管（DWCNTs）的薄膜场效应晶体管（TFT）中同时实现高灵敏度和选择性。我们用羧酸功能化的 DWCNT TFT 获得了优异的栅极调制（高达 4000 的开关比），同时在 CNT 的面积密度低至 35ng/cm(2)时获得了较高的导通电流。该器件对 NH(3)的灵敏度为 60nM（或约 1ppb），与使用最先进的 SWCNT TFT 传感器的小分子水溶液检测相当，同时对各种含胺分析物分子的化学选择性比其他小分子高 6000 倍。这些结果突出了使用共价功能化的双壁碳纳米管同时进行超高选择性和灵敏的化学检测的潜力，并说明了这种双壁材料策略在纳米电子学中的一些结构优势。
