Carbon and cobalt co-doped ZnO thin films for highly sensitive and selective ammonia detection at room temperature†

This study focuses on developing room temperature (300 K) ammonia sensors utilizing carbon doped and co-doped (carbon and cobalt) zinc oxide (ZnO) thin films fabricated through the chemical spray pyrolysis technique. Spray pyrolysis is a cost-effective and scalable process for fabricating thin films for sensor applications. The structural analysis demonstrated that the deposited thin films have crystalline characteristics required for practical gas sensing applications. The gas sensing capabilities of both thin films were thoroughly investigated; notably, the carbon and cobalt co-doped ZnO sensors demonstrated good selectivity and sensitivity to ammonia gas at ambient temperature. The co-doped sensors were susceptible, detecting trace levels of ammonia even at ambient temperature. The response for 5 ppm of ammonia was 851 at 300 K, while for 50 ppm of ammonia, it was 2729. This significant attribute eliminates the need for elevated operating temperatures, reducing energy consumption and enhancing device longevity. The observed response to ammonia at 300 K underscores the potential of carbon and cobalt co-doped thin films as promising candidates for practical gas sensing applications.