Comparative study on gas sensing by a Schottky diode electrode prepared with graphene–semiconductor–polymer nanocomposites

Abstract

This paper studies the performance of a gas sensor based on an organic/inorganic diode for ammonia (NH₃), nitrogen (N₂) & oxygen (O₂) sensing under atmospheric conditions at room temperature and different humidity levels. The diode structure consists of a layer of different kinds of polymer (PTFE, PVDF, PANI) deposited on top of BiVO₄. The polymer layer, which is filled with different ratios of graphene oxide (GO), is prepared from the solution phase. We show that the current–voltage (I–V) response of the diode and the sensing performance are improved significantly by adding GO to the polymer layer. The sensing response is highest for a diode with 0.04 wt% of GO. At room temperature, the poly-GO (0.04 wt%)/BiVO₄ Schottky diode shows a sensitivity of 194 ppm upon exposure to 20 ppm of NH₃ in ambient air with rapid response and recovery times between 95 and 101 s, respectively. The sensor based on the polymer–GO diode is cost-effective, environmentally friendly, and easy to fabricate using low-cost solution-processing methods.