Direct ink writing of nickel oxide-based thin films for room temperature gas detection

The rapid industrial growth and increasing population have led to significant pollution and deterioration of the natural atmospheric environment. Major atmospheric pollutants include NO2 and CO2. Hence, it is imperative to develop NO2 and CO2 sensors for ambient conditions, that can be used in indoor air quality monitoring, breath analysis, food spoilage detection,etc. In the present study, two thin film nanocomposite（nickel oxide-graphene and nickel oxide-silver nanowires） gas sensors are fabricated using direct ink writing. The nano-composites are investigated for their structural, optical, and electrical properties. Later the nano-composite is deposited on the interdigitated electrode（IDE） pattern to form NO2 and CO2 sensors. The deposited films are then exposed to NO2 and CO2 gases separately and their response and recovery times are determined using a custom-built gas sensing setup. Nickel oxide-graphene provides a good response time and recovery time of 10 and 9 s,respectively for NO2, due to the higher electron affinity of graphene towards NO2. Nickel oxide-silver nanowire nano-composite is suited for CO2 gas because silver is an excellent electrocatalyst for CO2 by giving response and recovery times of 11 s each. This is the first report showcasing Ni O nano-composites for NO2 and CO2 sensing at room temperature.