Cu-doped ZnO thin film was synthesized on glass substrate using chemical bath deposition method at room temperature, exhibiting a hexagonal wurtzite structure with a crystallite size of 17.53 nm for 5 wt% Cu doping. The SEM image of the film’s crystallites displays a spherical morphology with an average size of approximately 100 nm. Gas sensing studies towards NO2 gas revealed a linear response up to 50 ppm with sensitivities of 1.64, 2.17, and 3.11 for 10, 25, and 50 ppm, respectively and 3.72 at 100 ppm without full saturation. Response time and recovery time ranged from 30–60 seconds and 25–300 seconds respectively, highlighting the rapid sensing capabilities of the material. Compared to pure ZnO, the Cu-doped ZnO thin film exhibited comparable sensitivity but significantly faster response times, enhancing its suitability for real-time gas detection.
