Fabrication of suspended nanowires using suspended carbon nanotubes as template for gas sensing

Abstract

We developed a novel approach to fabricate suspended metal- and metal oxide nanowires using carbon nanotubes (CNTs) as sacrificial template. As a potential application that harnesses the unique properties of suspended nanowires, sensitive chemical sensors were demonstrated. The suspended CNTs template was synthesized on the side wall of the electrodes by chemical vapor deposition (CVD), followed by the deposition of nanomaterials on top of the CNTs by evaporation. The CNTs template was completely removed during the oxidation process while the remained nanowires had the identical geometry to the CNTs. Because all the fabrication procedure consists of dry and batch processes, it is possible to mass-produce the sensors without contamination or damage of the nanowires. The fabricated WO ₃ nano wire-based sensor successfully detected 100 ppm of NO ₂ at a temperature of 300 °C. The sensing performance of the sensor is attributed to the high surface area of the suspended morphology and small diameter of the nanowires.