Fabrication of a Room Temperature Ammonia Gas Sensor Based on Polyaniline With N-Doped Graphene Quantum Dots

Abstract

In this paper, we have investigated a resistive ammonia (NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) gas sensor fabricated with a combination of polyaniline (PANI) as a conductive polymer and different weight percentages of nitrogen-doped graphene quantum dots (N-GQDs). We used two different metals of silver (Ag) and aluminium (Al) as electrodes to the sensing films. It has been found that Ag contact showed an ohmic behaviour and Al electrode exhibited a Schottky junction. This paper presented here shows that the sensor with Ag electrode has much higher response to NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> than that of the sensor with Al electrode. The sensor of (50wt%)N-GQDs/PANI with Ag contact exhibited the best response of 110.92 towards 1500 ppm NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> at room temperature. However, a much response of 86.91 was measured for the sensor with Al electrode. Fourier transform infrared spectroscopy of the synthesized structure was investigated to analyze the differences between pure PANI and N-GQDs/PANI. Further, field emissions scanning electron microscopy was used to characterize sensing samples.