NO2 gas sensing properties of Au-functionalized porous ZnO nanosheets enhanced by UV irradiation

Porous ZnO nanosheets were synthesized by thermal evaporation. The morphology, crystal structure, and sensing properties of the ZnO nanosheets to NO2 gas at room temperature under UV illumination were examined. Au nanoparticles with diameters of a few tens of nanometers were distributed over the ZnO nanosheets. The responses of the multiple networked nanosheet gas sensors were improved 1.8-3.3 fold by Au functionalization at NO2 concentrations ranging from 1 to 5 ppm. Furthermore, the Au-functionalized ZnO nanosheet gas sensors showed a considerably enhanced response at room temperature under ultraviolet (UV) illumination. In addition, the mechanisms through which the gas sensing properties of ZnO nanosheets are enhanced by Au functionalization and UV irradiation are discussed.