Characteristics of ZnO nanorods-based ammonia gas sensors with a cross-linked configuration

Cross-linked ZnO nanorods (NRs)-based ammonia gas sensors have been fabricated and investigated. The influences of interdigitated electrode spacing d and working temperature on ammonia sensing performance are studied. It is found that when the electrode spacing d is reduced, the ammonia sensor response S would be increased due to the configuration transformation of ZnO NRs. The optimal working temperature is about 573 K due to the temperature dependence on reactions of oxygen species. The studied sensor with an electrode spacing d of 2 μm shows a maximum ammonia sensor response S of 81.6 under exposing to a 1000 ppm NH₃/air gas at 573 K. Also, a lower detection limit of 10 ppm NH₃/air is achieved. The improved ammonia detecting capability could be attributed to the formation of more cross-linked configurations. The adsorption-time (τ_a) and desorption-time (τ_b) constants of the studied sensor with an electrode spacing d of 2 μm, at 573 K, are 74 and 29 s, respectively. Finally, the studied sensor exhibits good gas sensing response and repeatability toward NH₃ gas. Thus, the studied sensor with a cross-linked configuration gives a promise for high-performance ammonia sensing applications.