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Currently, semiconductor gas sensors are being actively studied and used in various fields, including ecology, industry, and medical diagnostics. One of the major challenges is to reduce their operating temperature to room temperature. To address this issue, sensor layers based on WO3−x/WS2 nanostructures synthesized by the hydrothermal method have been proposed. In this paper, the morphology of the material's surface and its elemental composition were investigated, as well as the optical band gap. Additionally, changes in the resistance of the WO3−x/WS2 sensor layers under the influence of alcohol vapors at room temperature were analyzed. The results showed that the layers exhibited a significant response, with short response and recovery times. The achieved response value to 1000 ppm of isopropanol was 1.25, with a response time of 13 s and a recovery time of 12 s. The response to 1000 ppm of ethanol was 1.35, and the response and recovery times were 20 s. This indicates that these sensor layers have promising potential for various applications. [ABSTRACT FROM AUTHOR]

Today, air pollution is a global environmental problem. A huge amount of explosive and combustible gas emissions that negatively affect nature and human health. Gas sensors are one of the ways to prevent this impact. Several types of sensors have been developed, but the main problem with them is the high operating temperature. This leads to a decrease in reproducibility and stability over time. The aim of the work is to synthesize zinc stannate nanoparticles, study their phase composition, and modify the structure with silver nanoparticles to improve gas-sensing characteristics. This paper presents the synthesis of zinc stannate nanoparticles by the coprecipitation method and annealing at varying temperatures. A method of decorating zinc stannate with silver nanoparticles was proposed. Using XRD, it was found that a change in the annealing temperature leads to a change in the initial phase composition of the sample. Decoration with silver nanoparticles allows for increasing the sensor response of zinc stannate layers to isopropyl alcohol by 20 times. The corresponding increase in response to ethanol is 16 times. [ABSTRACT FROM AUTHOR]

This work is aimed at the development of a highly sensitive silicon (Si)-based sensor allowing for the selective detection and analysis of liquid solution compositions containing ammonia (NH3) and hydrochloric acid (HCl) in an indirect manner using electrochemical impedance spectroscopy (EIS). For optimization of the performance, we develop three types of sensors based on as-fabricated Si nanowires, nanowires treated with hydrofluoric acid (HF), and nanowires decorated with silver (Ag) nanoparticles. The fabricated sensors exhibit good performance governed by the sensitivity of the nanoscale Schottky barriers at the interface between the golden pads and Si nanowires. The best results on sensitivity are obtained with untreated Si nanowires providing a detection limit at the level of 4 μmol·L–1 and resistive sensitivities of 0.8% per μmol·L–1 for HCl and 4 μmol·L–1, −0.2% per μmol·L–1 for NH3, correspondingly. Treatment with HF stimulates the surface oxidation providing higher density of the adsorption sites and found promising for the detection with the analyte content up to 1000 μmol·L–1. In the end, we study the sensor response upon simultaneous exposure under NH3 and HCl vapors using developed approach for the EIS data analysis involving characterization of the sensor response with two parametersresistance and EIS frequency corresponding to the change in the operation regime. Due to the use of two parameters simultaneously, this approach is found as a pathway for qualitative analysis of the gas mixture composition using only one sensor. The results of the work shed light on the development of feasible highly sensitive sensors for health monitoring, allowing for selective mixed analytes detection. [ABSTRACT FROM AUTHOR]