Functionalized horizontally aligned CNT array and random CNT network for CO2 sensing

Abstract

Horizontally aligned and density-controlled single-wall carbon nanotubes (CNT) represent attractive building blocks for nanoelectronics. In this paper, horizontally aligned CNT arrays and random CNT network are synthesized by thermal CVD at 925 °C in an ethanol atmosphere. With appropriate functionalization applied to the aligned CNTs, a high sensitivity of 8.48% for ambient CO2 gas concentration of 500 ppm is achieved. In addition, these aligned CNT array sensors show much faster response and recovery time than a random CNT network. Moreover, good selectivity against NO2 and NH3, and good repeatability are demonstrated. These results pave the way for a deeper understanding of the physical and electrical properties of single-wall CNT and inter-tube junctions, which could be helpful in designing and optimizing as-grown single-wall CNT for gas sensor and other nanoelectronic devices.