Optimizing ammonia gas sensor performance: Investigating the influence of Mg doped ZnO root like nanostructures for enhanced gas sensing application

• 2% and 4% Mg doped ZnO nanostructures synthesized via chemical spray pyrolysis technique. • Prepared samples show hexagonal (wurtzite) structure with XRD peaks aligned towards c-axis (preferred orientation). • Crumby, Intertwined root like morphology for 4% Mg doped ZnO sample was achieved. • 4 % Mg doped ZnO nanostructures were highly selective and exhibited elevated response for 5 ppm NH 3 gas concentration at RT. • 4 % Mg doped ZnO root like nanostructures yielded robust response and recovery times (30 s and 7 s) towards ammonia gas. This work presents the synthesis of Mg-ZnO root-like nanostructures using chemical spray pyrolysis. Structural, morphological, gas sensing and optical properties were investigated. The films exhibit a hexagonal wurtzite ZnO crystal structure. Morphology changes from grain-like (2 % Mg) to root-like (4 % Mg). The 4 % Mg-ZnO nanostructures detect 5 ppm ammonia gas with a quick response (30 s) and recovery time (7 s). Higher Mg doping influences the optical energy bandgap. Mg-ZnO is a promising material for ammonia gas sensors and optoelectronic devices due to its gas sensing and optical properties.