Synthesis, structural evaluation of molybdenum oxide (MoO3) nanoparticles and its application as CO2 gas sensor

In the present study we report a simple eco-friendly hydrothermal protocol for the synthesis of molybdenum oxide (MoO3) nanoparticles at various temperatures i.e., 80-200 °C at intervals of 20 °C designated as S1-S6 sequentially with time duration of 4 h for each batch. The synthesized samples were characterized by X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Fourier Transform Infra-red (FTIR), UV- Visible Diffuse Reflectance (UV-Vis DRS), Laser Raman, Cyclic Voltammetry (CV), X-Ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM) to find out their elemental composition, structure, morphology and the optical band gap. The XRD analysis indicates well-crystallized orthorhombic structure with preferred orientation along (210) plane. The presence of O-Mo-O stretching vibration was observed by FTIR analysis The gas sensing studies were carried out to examine the material’s Sensitivity over a temperature range of 50oC to 400oC for various gas concentrations i.e. 200-1000 ppm of CO2 gas. The sensor had a Sensitivity of S=68.5% for S4 sample at an optimum temperature of 200 °C. The adsorption of desired gas on the material correlated well with the particle size of material at different temperature. The response and recovery times were 50 s and 40 s respectively.