A review on the sensing performances for three different ternary hybrid (Pd/RGO/TiO2-NTs, Pd/RGO/MnO2-NFs and Pd/RGO/WO3-NFs) gas sensor device structures

Abstract

Present paper aims to study the comparative analysis of the sensing performance between three fabricated metal oxide based ternary hybrid device structures [Pd/RGO/TiO2-nanotubes (NTs), Pd/RGO/MnO2 nanoflowers (NFs) and Pd/RGO/WO3-nanoflowers (NFs)]. In each of the ternary structure, the oxide nanostructure play the role of basic sensing matrix where due to extremely high surface to volume ratio of the corresponding nanostructure, the availability of adsorption sites increases, which leads to increased sensitivity or response magnitude (%RM) of the sensor. On the contrary, RGO acts on a high mobility (~ 1600 cm2/V-s) distributed connector among the neighbouring nanostructure leading towards improved response or recovery kinetics. Finally, Pd nanoparticles due to their catalytic activity (which reduces activation energy requirement for target species dissociation), bring forth as the substantial reduction in operating temperature. By employing those ternary hybrid structure sensing layers, room temperature (27 °C) alcohol sensing with a very high detection range (1–700 ppm) was achieved with appreciably fast response time (~ 12–20 s) and recovery time (~ 23–30 s) without compromising the response magnitude (80–98% at 700 ppm). Finally, a comparative analysis of the sensing performances for the above-mentioned three ternary hybrid gas sensors was illustrated.