Impact of Ag on the Limit of Detection towards NH3-Sensing in Spray-Coated WO3 Thin-Films

Ag-doped WO3 (Ag–WO3) films were deposited on a soda-lime glass substrate via a facile spray pyrolysis technique. The surface roughness of the films varied between 0.6 nm and 4.3 nm, as verified by the Atomic Force Microscopy (AFM) studies. Ammonia (NH3)-sensing measurements of the films were performed for various concentrations at an optimum sensor working temperature of 200 °C. Enrichment of oxygen vacancies confirmed by X-ray Photoelectron Spectroscopy (XPS) in 1% Ag–WO3 enhanced the sensor response from 1.06 to 3.29, approximately 3 times higher than that of undoped WO3. Limit of detection (LOD) up to 500 ppb is achieved for 1% Ag–WO3, substantiating the role of Ag in improving sensor performance

An 8 MeV Electron Beam Modified In:ZnO Thin Films for CO Gas Sensing towards Low Concentration

In the present investigation, electron beam-influenced modifications on the CO gas sensing properties of indium doped ZnO (IZO) thin films were reported. Dose rates of 5, 10, and 15 kGy were irradiated to the IZO nano films while maintaining the In doping concentration to be 15 wt%. The wurtzite structure of IZO films is observed from XRD studies post electron beam irradiation, confirming structural stability, even in the intense radiation environment. The surface morphological studies by SEM confirms the granular structure with distinct and sharp grain boundaries for 5 kGy and 10 kGy irradiated films whereas the IZO film irradiated at 15 kGy shows the deterioration of defined grains. The presence of defects viz oxygen vacancies, interstitials are recorded from room temperature photoluminescence (RTPL) studies. The CO gas sensing estimations were executed at an optimized operating temperature of 300 °C for 1 ppm, 2 ppm, 3 ppm, 4 ppm, and 5 ppm. The 10 kGy treated IZO film displayed an enhanced sensor response of 2.61 towards low concentrations of 1 ppm and 4.35 towards 5 ppm. The enhancement in sensor response after irradiation is assigned to the growth in oxygen vacancies and well-defined grain boundaries since the former and latter act as vital adsorption locations for the CO gas