Gas Microsensors with Metalloporphyrin-Functionalized Carbon Nanotube Networked Layers (original) (raw)

Abstract

Networked carbon nanotubes (CNTs) films have been grown by chemical vapor deposition (CVD) technology onto miniaturized Co-coated alumina substrates for NO2 and NH3 gas sensing applications, at a sensor temperature of 150°C. The sidewalls of the CNTs films have been modified by spray-coating with two different metalloporphyrins (MPPs) consisting of a TetraPhenylPorphyrin coordinated by a central metal of zinc (Zn-TPP) and manganese (Mn-TPP) for enhanced sensitivity and tailored specificity. It was demonstrated that the gas sensitivity of the MPPs-modified CNTs-sensors significantly improved by a factor up to four-times through a catalytic effect of the MPPs. The gas sensing properties of CNTs-sensors, including MPPs-modified CNTs, are characterized by a change of the electrical conductivity in a model of charge transfer with a semiconducting p-type character. A response of the CNTs-sensor functionalized with 2 spray-layers of Mn-TPP has been measured as 0.43% to 0.5 ppm NO2, and as 0.09% to 10 ppm NH3, at 150°C. The MPPs-functionalized CNTs-sensors exhibit high sensitivity, fast response, reversibility, good repeatability, sub-ppm range detection limit.

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