NO2 sensing properties of chemically deposited vertically aligned flowerlike hexagonal ZnO nanorods

The flowerlike hexagonal ZnO nanorods with pore between them were deposited under controlled synthesis using chemical bath deposition (CBD) method at various deposition times of 5, 6, 7 and 8 h. XRD study revealed the wurtzite crystal structure of ZnO whereas FESEM analysis revealed the vertically aligned flowerlike porous hexagonal nanorods. For ZnO deposited at 7 h, AFM exhibited surface roughness of 215.4 nm whereas BET study gives specific surface area of 3.76 m(2)g(-1). ZnO deposited for 7 h showed highest response of 36.4 % to 100 ppm NO2 at 200 degrees C with T-response of 10 s and T-recovery of 135 s. The controlling hexagonal ZnO nanorods form affects the crystallographic facets and pore size that provides that more surface accessibility site due to high surface to volume ratio which in turn allows ZnO nanorods reactivity to tune for NO2 sensing. Finally, detailed NO2 sensing mechanism of ZnO nanorods is proposed.