NO2 sensing properties of 3D flower-like ZnO nanostructure decorated with thin porous petals synthesized using a simple sol–gel drop-casting method

A three-dimensional flower-like ZnO nanostructured film decorated with the thin porous ‘petals’ is synthesized using an inexpensive sol–gel drop-casting method, and the NO2 detection characteristics of the nanostructured film are studied. The gas-sensing study shows higher sensitivity with selectivity toward NO2 gas, exhibiting good reproducibility and stability. The as-synthesized nanostructured 3D flower-like ZnO film shows excellent NO2 sensing performance, with a maximum gas response of 23.3 for 100 ppm NO2 gas at an operating temperature of 180 °C. A detailed gas-sensing study reveals that the enormous porous petals with various inter-connected pores fused on the flower-like ZnO nanostructure improve the adsorption of gas molecules; consequently, the synthesized ZnO nanostructure exhibits a superior level of NO2 gas-sensing activity. This study provides a promising path towards the development of a highly sensitive NO2 gas sensor and an easy way to fabricate the 3D morphology decorated with exceedingly porous ‘petals’.