Study on performance improvement of zinc oxide gas sensor with silver nanoparticles surface modification

This study used ZnO nano-rods grown on sapphire substrates by metalorganic chemical vapor deposition , focusing on the fabrication and performance improvement of gas sensor characteristics. Despite the potential of metal oxide semiconductor gas sensors, their commercialization remains limited due to challenges related to selectivity, operating temperature, and detection limits. The performance of these sensors is primarily influenced by surface area and the presence of oxygen vacancies . This investigation aimed to enhance these critical parameters through various techniques and to systematically analyze their impact on sensor performance. The ZnO-based sensor demonstrated optimal performance at an operating temperature of 300°C, exhibiting response levels of 97.82 % for 1 ppm concentration s of NO₂ gas, respectively. By incorporating hydrothermally grown ZnO nanostructures and Ag nanoparticles via sputtering, the study achieved an increase in surface area and surface roughness, which effectively augmented gas adsorption sites. Effects of varying sputtering power for Ag nanoparticles on sensor performance were also examined. At a sputtering power of 25 W with an average Ag particle size of 3.2 nm, the sensor demonstrated a marked improvement in its response to NO₂, achieving 434.3 % at 250°C for a 1 ppm concentration, with a detection limit reaching as low as 1 ppb. Furthermore, the sensor displayed excellent repeatability and long-term stability, highlighting its suitability for real-time monitoring of low-concentration hazardous gases in environmental applications. • A remarkable improvement in NO 2 detection, with response increasing to 434.3 % at 250°C for AgNP-decorated ZnO. • ZnO nanorods were modified with AgNPs, enhancing the surface area and gas adsorption sites. • AgNPs enhance the catalytic and electronic sensitization properties of the ZnO surface. • Two mechanisms of chemical and electronic were confirmed via XPS and DFT simulations.