Chemiresistive gas sensor for the sensitive detection of nitrogen dioxide based on nitrogen doped graphene nanosheets

Abstract

In this paper, we report on the development of a chemiresistive sensor for the detection of nitrogen dioxide (NO₂) gas at room temperature using nitrogen-doped graphene nanosheets (NGS). The substitution of the nitrogen atoms in the honey-comb structure of graphene enhances the adsorption sites for gas molecules and thereby the sensitivity of the detection of the adsorbed gas molecules increases. Graphene nanosheets (GS) and NGS were prepared by hydrothermal treatment of graphene oxide in the absence and presence of nitrogen precursor respectively. The sensing materials were characterized by FESEM, TEM, XRD, XPS and elemental analysis. The nitrogen content in as-prepared NGS is at around 10%. The thin films of GS and NGS on pre-patterned gold interdigitated electrodes (IDEs) were obtained by the drop-drying method. The NGS coated sensor showed good response for sensing NO₂ in comparison to that of GS at room temperature. The recovery of the sensor was greatly accelerated by ultra-violet light illumination. The proposed sensor showed excellent characteristics such as a low detection limit of 120 ppb (at S/N = 3). The effect of humidity on sensor performance was also studied. The proposed sensor also showed excellent selectivity with respect to various common interfering gases.