Promoted room-temperature LPG gas sensor activities of graphene oxide@Fe2O3 composite sensor over individuals

Abstract

Graphene oxide (GO), iron oxide (Fe2O3) and GO@Fe2O3 composite sensors, obtained at 0.1, 1.0, 10 wt% concentrations of GO in Fe2O3, of different structures, morphologies, porosities, surface areas, and charge transfer resistances, etc, have been synthesized via a simple, economic, solid-state synthesis strategy and envisaged as an efficient room-temperature (27 °C) liquefied petroleum gas (LPG) sensors. Spherical Fe2O3 and island-type GO have contributed their individual the sensing signatures in GO@Fe2O3 composite sensors. With GO loading in various wt%, intensity of the reflection peaks of Fe2O3 in x-ray diffraction patterns decreases, indicating dominance of an amorphous contribution in GO@Fe2O3. The electrical conductivity of the composite sensor decreases due to generation of various charge transport channels with increase of GO wt% concentration. However, for concentrations more than 1 wt% of the GO both pore-size and surface area of GO@Fe2O3 decreases. The 1 wt% GO@Fe2O3 composite sensor reveals ∼35% room-temperature (27 °C) LPG sensitivity @100 ppm level over pristine GO (∼15%) and Fe2O3 (∼25%), and also other GO@Fe2O3 composite sensors (20%–30%), attributed to their increased specific surface area and reduced charge transfer resistance, which, in general, have more surface active surface sites for adsorbing LPG molecules than those of individual and other low-surface area sensors.