The effect of light irradiation on the gas-sensing properties of nanocomposites based on ZnO and Ag nanoparticles

Highly porous pure and silver-doped ZnO 3D nanostructures were formed by PLD in open air with a view of sensor applications. Under irradiation with UV light, the response of pure ZnO and of Ag-ZnO sensor elements was studied to NH3, CO, ethanol, and acetone. The presence of Ag nanoparticles in the ZnO nanostructure improved considerably the sensor elements' response to all tested gases. Further, the effect was investigated of simultaneous UV and red light irradiation on the sensor elements' response and time of response and recovery. It was found that UV and optimized red irradiation resulted in enhancing the Ag-ZnO sensor's response to CO, while suppressing its response to NH3, ethanol, and acetone. The nanocomposite sensor exhibited a strong and stable response signal at 1 ppm CO exposure, which made us presume that measuring lower concentrations is also achievable.