Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
Nano Lett. 2012 Mar 14;12(3):1729-35. doi: 10.1021/nl300427w. Epub 2012 Mar 6.
The formation of a nanometer-scale chemically responsive junction (CRJ) within a silver nanowire is described. A silver nanowire was first prepared on glass using the lithographically patterned nanowire electrodeposition method. A 1-5 nm gap was formed in this wire by electromigration. Finally, this gap was reconnected by applying a voltage ramp to the nanowire resulting in the formation of a resistive, ohmic CRJ. Exposure of this CRJ-containing nanowire to ammonia (NH(3)) induced a rapid (<30 s) and reversible resistance change that was as large as ΔR/R(0) = (+)138% in 7% NH(3) and observable down to 500 ppm NH(3). Exposure to water vapor produced a weaker resistance increase of ΔR/R(0,H(2)O) = (+)10-15% (for 2.3% water) while nitrogen dioxide (NO(2)) exposure induced a stronger concentration-normalized resistance decrease of ΔR/R(0,NO(2)) = (-)10-15% (for 500 ppm NO(2)). The proposed mechanism of the resistance response for a CRJ, supported by temperature-dependent measurements of the conductivity for CRJs and density functional theory calculations, is that semiconducting p-type Ag(x)O is formed within the CRJ and the binding of molecules to this Ag(x)O modulates its electrical resistance.
描述了在银纳米线内形成纳米级化学响应结（CRJ）的过程。首先使用图案化纳米线电沉积方法在玻璃上制备银纳米线。通过电迁移在该导线上形成 1-5nm 的间隙。最后，通过向纳米线施加电压斜坡使该间隙重新连接，从而形成电阻、欧姆 CRJ。将包含这种 CRJ 的纳米线暴露于氨（NH（3））会引起快速（<30s）和可逆的电阻变化，在 7%NH（3）中可达 ΔR/R（0）=（+）138%，在 500ppmNH（3）下也可观察到。暴露于水蒸气会产生较弱的电阻增加，ΔR/R（H（2）O）=（+）10-15%（对于 2.3%的水），而二氧化氮（NO（2））暴露会导致更强的浓度归一化电阻降低，ΔR/R（0，NO（2））=（-）10-15%（对于 500ppmNO（2））。通过对 CRJ 电导率的温度依赖性测量和密度泛函理论计算支持的 CRJ 电阻响应的提出的机制是，在 CRJ 内形成半导体 p 型 Ag（x）O，并且分子与该 Ag（x）O 的结合调节其电阻。
