Explosive molecule sensing at lattice defect sites in metallic carbon nanotubes

Abstract

Explosives and hazardous gas sensing using carbon nanotube (CNT) based sensors has been a focus of considerable experimental research. The simplest sensors have employed a chemiresistive sensing mechanism, and rely on substitutional doping or structural flaws (vacancy, divacancy, or Stone–Wales defects) to increase sensitivity. However since chemiresistive sensors often show poor selectivity, further improvements are needed. Ab initio analysis of the chemiresistive response of five metallic CNT sensors incorporating substitutional doping or structural flaws suggests that arrays of these devices may be effectively employed to improve selectivity. In particular, arrays composed of doped or flawed CNTs can distinguish nitroaromatic and nitramine explosive molecules from each other and from four common background gases. Array selectivity is improved by capitalizing upon the nonlinear current–voltage characteristics of the substitutionally doped or structurally flawed CNTs.