Highly sensitive and selective ethanol detection at room temperature utilizing holey SWCNT-Sn/SnO2 nanocomposites synthesized by microwave irradiation

Abstract

Carbon-based nanocomposites that can operate at room temperature (25 °C) are potential sensing materials for application in chemical sensors owing to their unique physical properties such as extremely large surface-to-volume ratios and very high carrier mobility. However, most studies on sensing materials consisting of carbon-based nanocomposites have focused on synthesizing various material systems that contain metals, oxides, and chalcogenides, which are of limited use in practical gas sensors owing to their low response, poor selectivity, and irreversibility. Therefore, a simple approach to synthesizing carbon-based nanocomposites with high response and good gas selectivity utilizing microwave (MW) irradiation is proposed, and the sensing mechanisms underlying the enhanced sensing performance are discussed in detail. First, the perforation of single-walled carbon nanotubes (SWCNTs) during MW irradiation is investigated systematically, and then nanocomposite gas sensors based on the opened SWCNTs with large surface areas and without additional functionalization are fabricated. The nanocomposite sensors exhibit an extremely high response (>6 at 10 ppm) and selectivity for ethanol (C2H5OH) at room temperature. In addition, the C2H5OH response of the holey SWCNT-Sn/SnO2 nanocomposites is much higher than those of carbon-based nanocomposites. These results show that the simple synthesis method utilizing MW irradiation would be useful for various material systems requiring surface engineering or functionalization.