Fabrication, Characterization, and Gas Sensing Performance of Pd, RGO, and MnO2 Nanoflowers-Based Ternary Junction Device

Abstract

Pd, reduced graphene oxide (RGO), and MnO2 nanoflowers-based ternary hybrid junction was fabricated, characterized, and its gas sensing potentiality was established and reported in this paper. Four different types of devices, viz., pristine MnO2 nanoflowers (Device I), Pd/MnO2 nanoflowers (Device II), RGO/MnO2 nanoflowers (Device III), and Pd/RGO/MnO2 nanoflowers (Device IV) were fabricated to study the influence of each of the elements and to account for its contribution towards improving the gas sensor device performance towards alcohol vapors as the test species. After detailed structural characterizations, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy, alcohol vapor sensing performance was studied using methanol, ethanol, and 2-propanol in the temperature range of room temperature (~27 °C) to 150 °C targeting the concentration range of 5–100 ppm. Ternary structure (Device IV) was found to offer remarkably superior performance in terms of response magnitude (RM) (~92.52% at 100 ppm), response time (~11 s), and recovery time (~16 s) compared to its binary (For Pd/MnO2: (~86.86%, ~36 s, ~43 s and for RGO/MnO2: ~80.85%, ~21 s, ~27 s) or pristine counterparts (~27.22%, ~59 s, ~67 s). The plausible cause of such remarkable improvement was attributed to the synergistic contribution of both RGO and Pd. While Pd as a catalyst helped in easy dissociation of target species ensuring the improved performance at low temperature, RGO enhanced the vapor adsorption rate due to of its additional adsorption sites and fast response/recovery kinetics due to high carrier mobility.