Recent progress in hybrid conducting polymers and metal oxide nanocomposite for room-temperature gas sensor applications: A review

The rapid development of conducting polymers has demonstrated great potential for chemical gas detection at room temperature. Their electrical conductivity can be altered when oxidative or reducing gas molecules are exposed at room temperature. However, due to their relatively low conductivity and high affinity for volatile organic compounds and water molecules, they always have low sensitivity, poor stability, and gas selectivity, which hamper their practical gas sensor applications. In addition, metal oxide-sensitive materials show completely different advantages in gas sensors, such as high sensitivity, fast response to analyses in low concentration, large surface area, and versatile surface chemistry, which could complement the conducting polymers in terms of sensor properties. Various conductive polymer-metal oxide hybrid nanocomposites have been used for toxic gas detection. Composites of different conductive polymer materials such as polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh), poly(-phenylenevinylene) (PPV), poly(3,4-ethylene dioxythiophene) (PEDOT), etc. with various metal oxides have been identified due to their nanoparticles unique redox properties, conductivity and simple function at room temperature as sensor materials for gas sensors. Conducting polymer nanohybrids showed better performance due to the larger surface area of nanohybrids and the synergistic effect between conducting polymer and metal oxide materials. In this review paper, we discussed the most recent advancements in conducting polymer-metal oxide hybrid nanocomposites for the room-temperature detection of harmful gases such as NH3, H2, H2S, NOx, and LPG. Furthermore, the impacts of different parameters variations on conductive polymer-metal oxide hybrid nanocomposite sensors are investigated. Finally, we summarize challenges and future prospects for room-temperature conductive polymer-metal oxide hybrid nanocomposite gas sensors.