Ammonia gas detection by solution combustion-processed pristine & Ti-doped ZnO transparent films: a reverse effect of doping on gas response

Abstract

In this contribution, pure, polycrystalline wurtzite crystal structured, spin-coated pristine ZnO and Ti-doped (1, 2, and 3 wt%) ZnO transparent films were accomplished at 400 °C through a facile solution combustion synthesis method. Crystallinity, roughness, and porosity in the pristine film were relatively higher than in the doped films. The demonstrated films were transparent, with ~ 70 to 90% in the visible region. The room temperature detection of ammonia (NH<inf>3</inf>) gas (25–100 ppm) was recognized in all the films. The pristine film revealed a superior gas response at every concentration of NH<inf>3</inf> gas in contrast to all the doped films; it is probably due to comparatively high crystallinity, porosity, more oxygen vacancy concentration (1.788), and high fraction of adsorbed oxygen (20.55%). The film exhibited the highest gas response of 34.7 at 100 ppm of NH<inf>3</inf> gas and a limit of detection of ~ 10.7 ppm with superior selectivity towards NH<inf>3</inf> gas. Although doping enhanced the transparency but diminished the NH<inf>3</inf> gas response due to the combined effect of deterioration in the mentioned properties achieved in pristine film. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.