Synthesis, characterization, and gas sensing application of crumpled CdO sheets prepared in alkaline media

CdO crumpled sheets have been synthesized by microwave-assisted irradiation in alkaline solutions of NH4OH and NaOH, respectively, and in presence of a surfactant. The morphology of CdO samples have been investigated using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). X-ray diffraction analysis (XRD) has been used to determine the cadmium oxy/hydroxide crystalline phases of CdO formed during synthesis and successive annealing at 300 °C. Crystallite sizes of CdO nanostructures obtained from NH4OH and NaOH reagent-assisted synthesis are 44 nm and 57 nm, respectively. The specific surface area (SSA), lattice parameter, X-ray density, dislocation density, macrostrain, and texture coefficient (TC), have also been determined. The optical characteristics of CdO samples were investigated using UV reflectance (DRS) and K-M plot. NO2 gas detecting capabilities of CdO nanostructures have been investigated at low working temperature of 150 °C. When compared to its NaOH counterpart, the CdO sample prepared by NH4OH reagent-assisted synthesis demonstrated a superior sensitivity to NO2, being demonstrated even at the low concentration of 0.14 ppm, with excellent selectivity.