In this study, ZnO-TiO2 nanostructures were successfully synthesized via a low-temperature chemical bath deposition (CBD) method for NH₃ gas sensing applications. TiO₂ doping concentrations (5% and 20%) were investigated to optimize the sensing performance. Structural analysis verified hexagonal wurtzite ZnO and anatase TiO₂ formation. FE-SEM showed semi-spherical particles averaging 17.96 nm for ZnO and 39.1 nm for TiO₂. The gas sensing results demonstrated superior performance for the 20% TiO₂-doped sample, exhibiting a sensitivity of 135% at 100 ppm NH₃, compared to 110% for the 5% sample. Furthermore, the 20% TiO2-doped sensor showed enhanced response kinetics with a faster response time of 35 seconds and recovery time of 95 seconds, compared to 45 seconds and 120 seconds respectively, for the 5% sample. This improved performance is attributed to the formation of optimal n-n heterojunctions at the ZnO-TiO₂ interface, increased oxygen vacancies, and enhanced electron transport network, making the 20% TiO₂-doped ZnO nanostructure an efficient room-temperature NH₃ gas sensing material.
