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>I</i>-<i>V</i>) 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.