Hierarchical 3D nanostructure of GdInO3 and reduced-graphene-decorated GdInO3 nanocomposite for CO sensing applications

Metal oxide/graphene nanocomposites have received great attention in various fields of science and technology especially for developing high-performance chemical gas sensors. Herein, we demonstrate in detail the facile hydrothermal synthesis route for the preparation of mesoporous hierarchical GdInO3 and reduced graphene oxide (rGO) decorated GdInO3 composites as a selective carbon monoxide (CO) sensor. The synthesized materials were characterized in detail by several analytical techniques such as TGA, FT-IR, Raman, XRD, and XPS. The morphological evaluations of the materials were carried out by field emission scanning electron microscopy and transmission electron microscopy along with the selected area electron diffraction analysis. The detailed electron microscopy investigations of GdInO3 reveal the self-assembly of smaller nanoparticles into hierarchical structures resembling nanorods which aggregate further into the sphere like morphology. The surface area and pore size disruption of the materials were carried out by N2 adsorption/desorption isotherm analysis. The CO sensing characteristics of rGO/GdInO3 nanocomposite clearly shows the maximum sensor response (S ∼100) with appreciably fast response (ΓRES ∼ 14 s) and recovery time (ΓREC ∼ 15 s) towards 100 ppm of CO at 90 °C whereas the sensor response of pure GdInO3 reaches a maximum limit (S ∼ 70) at ∼150 °C. Furthermore, the sensors also displayed very high selectivity towards CO compared to other interfering gases. Therefore, the rGO decorated GdInO3 is a promising candidate for fast, sensitive and selective detection of CO at low operating temperatures.