ORIGINAL PAPER Resistive room temperature LPG sensor based on a graphene/CdO nanocomposite Solleti Goutham 1 & Naradala Jayarambabu 1 & Chinta Sandeep 2 & Kishor Kumar Sadasivuni 3 & Devarai Santhosh Kumar 4 & Kalagadda Venkateswara Rao 1 Received: 26 July 2018 /Accepted: 12 December 2018 # Springer-Verlag GmbH Austria, part of Springer Nature 2019 Abstract The authors decribe an ultra-sensitive, room temperature, flexible transparent LPG sensor based on the use of a CdO/graphene nanocomposite. The graphene prevents the accumulation of CdO, enhances the surface area, and acts as a gas sensing material. FESEM images show a uniform decoration of CdO nanoparticles on graphene. The CdO/graphene composite was deposited as a film on interdigitated electrodes (IDEs) which then were used for chemiresistive sensing of liquid petroleum gas (LPG) by using a four probe technique. A Resistivity decreases significantly upon exposure to a LPG. The electrical resistance measurement at a constant bias voltage of 0.5 V. The sensor of type CdO/graphene (1 wt.%) exhibits a sensitivity of 600 ppm of LPG at 27 °C. It is a highly selective, stable and sensitive to low concentration of LPG even at room temperature. Keywords Liquefied petroleum gas . Graphene . CdO . Gas sensor . Flexible Introduction Numerous types of solid-state gas sensors are engaged in com- mercial sensing applications. Particularly, nanostructured metal oxide semiconductors are conventional and widespread for de- tection of explosives, toxic materials and poisonous gases [1, 2]. Metal oxides with low-dimensional nanostructured mate- rials have been rapidly increasing in gas sensing technology. Graphene is identified as a center of significant advances, due to its amazing chemical and physical properties [3–6]. It can be used in diverse possible technological applications such as elec- trical and electronics [7], energy storage [8], energy genera- tions, actuators, gas sensors [9, 10], transparent conductors [11] and detectors [12]. Also, it has a high surface to volume ratio which can be interpreted into rapid and low operating temperature gas sensor applications through the chemisorption mechanism [9, 13]. The synergistic effect based on the metal oxide/graphene combination for the improved sensitivity and selectivity of gas sensors is well established [14]. Jaeseok et al. reported gas sensors based on graphene/ZnO nanorods for the detection of ethanol at 300 °C [15]. J. Tian et al. reported an ammonia gas sensor using bulk-reduced TiO 2 , graphene oxide and polyaniline and observed excellent sensing from 5 to 300 ppm of ammonia, at room temperature [ 16, 17]. However, very few metal oxide and graphene-based gas sen- sors working at room temperature exist, at present. Therefore, few-layered graphene (FLG) combined with ap- propriate metal oxide particles can be a cutting-edge technol- ogy towards the enhancement of gas sensing performance. Nevertheless, no such efforts have been designed towards the improvement of ultrasensitive flexible room temperature LPG sensors. In this present investigation, CdO/graphene nanocomposite flexible device by using a low-cost ultrasonic Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-018-3170-2) contains supplementary material, which is available to authorized users. * Kalagadda Venkateswara Rao kalagadda2003@gmail.com 1 Nano Electronics Laboratory, Centre for Nano Science and Technology, JNT University Hyderabad, Kukatpally, Telangana 500085, India 2 Department of Mechanical Engineering, Institute of Aeronautical Engineering, Dundigal, Hyderabad, Telangana 500043, India 3 Department of Mechanical and Industrial Engineering, Qatar University, P.O. Box 2713, Doha, Qatar 4 Department of Chemical Engineering, IIT-Hyderabad, Kandi, Hyderabad, Telangana 502285, India Microchimica Acta https://doi.org/10.1007/s00604-018-3170-2