Arc-discharge deposition of SWCNTs over SnO₂ nanowires for highly sensitive NO₂ gas sensor

Abstract

The air pollution caused by the emission of NO2 from vehicles in large cities is threatening human health. Thus, a highly sensitive gas sensor is required to monitor this gas. Here, we introduced the arc-discharge deposition of single-walled carbon nanotubes (SWCNTs) over SnO2 nanowires for highly sensitive NO2 gas sensors. The high-quality SnO2 nanowires were grown on-chip on interdigital Pt electrodes, whereas the SWCNTs were deposited by in situ arc-discharge method. To form the heterojunction between SnO2 nanowires and SWCNTs film, we controlled the length of the SnO2 nanowires to avoid bridging of the two electrode fingers while covering the entire surface of Pt electrodes. The SWCNTs were deposited through a shadow mask to ensure the contact between the SWCNTs and SnO2 nanowires but not the Pt electrodes. Electrical measurements confirmed the formation of non-linear contact between SnO2 nanowires and SWCNTs because of the n-p heterojunction. An increment in resistance (decrease in resistance) of the sensor was observed when measured in NO2 gas, indicating the good response characteristics of the device based on heterojunction between SnO2 nanowires and SWCNTs. In addition, gas-sensing measurement at different temperatures indicated that the fabricated sensor could detect low concentrations of NO2 gas in the range of 1–10 ppm, with response values of 20–80. The results demonstrated that the arc-discharge deposition of SWCNTs over SnO2 nanowires is effective for the fabrication of highly sensitive NO2 gas sensors.

Conductive polythiophene/graphitic-carbon nitride nanocomposite for the detection of ethanol mixing in petrol

“…The development of chemical/gas/ vapour sensors has recently focused heavily on carbon nanomaterials, metal oxide semiconductors, conductive polymers (CPs) and their nanocomposites. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] Due to its extraordinary functionalities through regulated charge transfer process, adjustable electrical conductivities, and self-resistivity changes upon exposure to various gases, conducting polymers have long been sought aer as chemiresistor materials. [16][17][18][19][20][21] Due to its extraordinary functionalities through regulated charge transfer process, adjustable electrical conductivities along with selfresistivity which alters when exposed to variety of gases, CPs have for a long time been used as chemiresistor.…”

“…[16][17][18][19][20][21] Due to its extraordinary functionalities through regulated charge transfer process, adjustable electrical conductivities along with selfresistivity which alters when exposed to variety of gases, CPs have for a long time been used as chemiresistor. [9][10][11][12][13] Polythiophene (PTh) being chemically, thermally and environmentally highly durable is amongst the most researched CPs. PTh and its derivatives stood out among gas sensors owing to their distinctive doping and de-doping mechanisms that produce a change in electrical conductivity when exposed to various chemicals and gases.…”