Ammonia-Sensing Using a Composite of Graphene Oxide and Conducting Polymer

The paper studies the performance of a gas sensor based on an organic/inorganic diode for ammonia (NH₃) sensing under atmospheric conditions at room temperature and different humidity levels. The diode structure consists of a layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) deposited on top of n-type GaAs. The PEDOT:PSS layer that 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 improve significantly by adding GO to the PEDOT:PSS layer. The sensing response is highest for a diode with 0.04 wt.% of GO. At room temperature, the PEDOT:PSS:GO (0.04 wt.%)/n-GaAs Schottky diode shows a sensitivity of 194 upon exposure to 20 ppm of NH₃ with rapid response and recovery times between 95 and 121 s, respectively. The NH₃ sensor based on PEDOT:PSS:GO is cost-effective, environmentally friendly, and easy to fabricate using low-cost solution-processing methods.