2026/01/01 by Narimann Neamah Hussein, Taghreed N. Jamil, Ali J. Khalaf +4 · 1 voice
Engineering · Materials Science · #Gas Sensing Nanomaterials and Sensors #ZnO doping and properties #Copper-based nanomaterials and applications
paper · pdf · doi:10.1515/ntrev-2025-0271
openalex publication_date 2026/01/01 · openalex created_date 2026/03/12 · openalex updated_date 2026/08/01
Abstract Silver oxide (Ag 2 O) thin films have been widely used as an active element for gas sensing. In this study, nanostructured silver oxide thin films were prepared using a drop casting technique. XRD confirms the formation of thin films of the crystal structure of silver oxide was found to be cubic, and that of manganese oxide was tetragonal. The remaining oxides were found to have a crystal structure belonging to the spinal family. Average of crystallite size 74.0868–63.298 nm. FE-SEM analysis of the silver tin oxide film appears to be in the form of small, semi-spherical particles or granules from 68.64 to 29.08 nm. As for the rest of the overlapping thin-films, their shapes appear different. The performance of sensors is significantly impacted by the shape of the particles in thin films. Small, evenly spaced particles, as those in Ag 2 O supported by MnO 2 , expand the surface area that can interact with gases. This improves sensor sensitivity by making chemical and physical adsorption more effective. The exact form of the particles can also influence the film’s conductivity by lowering resistance and promoting electron mobility. All prepared thin films are high at short wavelengths, and we note that they fall within the visible region and thus can be used in gas sensor applications. It is also observed that the absorbance values increase with increasing manganese oxide content from 0.25 to 0.75 a.u. The energy gap values increase, which means that the overlap has shifted the absorption edge towards higher energies from 2.2 to 3.4 eV. This increase can be explained as a result of what is known as the Burstein–Moss shift. Finally, to improve the sensors’ response, high temperatures (75 °C) were used. In order to prevent gas leaks and to create an appropriate testing environment, the sensor chamber was made to be airtight. During the experiment, certain gas concentrations (100 ppm) were used. Because chemical reactions accelerated at high temperatures, response times were quick, which improved recovery time. The sensitivity of the films was assessed by testing their reaction to multiple gas types (NH 3 and CH 4 ). The findings indicated that as contaminants increased, so did sensitivity. The addition of MnO 2 appears to be significantly beneficial for methane detection, as the composite samples (2 and 4) showed a noticeably quicker response compared to the sample predominantly featuring Ag 2 O. Increasing the amount of MnO 2 also greatly improves the recovery duration for methane. Ideal sample (Sample 2): Sample 2, which consists of 0.006 M Ag 2 O and 0.004 M MnO 2 , is widely seen as the best and most well-balanced formulation. It achieves the quickest response time for methane, the second fastest for ammonia, and the fastest recovery time for ammonia. The combination of Ag 2 O with MnO 2 significantly boosts the sensing ability for methane in contrast to ammonia.