Controllable synthesis of zinc oxide hierarchical architectures and their excellent formaldehyde gas sensing performances

- Two kinds of ZnO flowerlike architectures are fabricated by facile routes.
- ZnO samples are assembled by porous-nanosheet and smooth-nanosheet, respectively.
- Porous-nanosheet assembled ZnO flowers show better formaldehyde sensing property.

Two kinds of ZnO hierarchical architectures are skillfully designed and successfully fabricated by facile room temperature solution routes followed by subsequent annealing treatments. SEM and XRD characterizations reveal that as-prepared ZnO products both present typical flowerlike morphologies but are assembled by abundant porous nanosheets and smooth nanosheets, respectively. Such hierarchical architectures are developed for formaldehyde (HCHO) detection. The gas sensing results indicate that porous-nanosheet assembled ZnO hierarchical architectures based sensors exhibit better HCHO gas sensing properties in terms of high sensitivity, good selectivity and rapid response/recovery time compared with smooth-nanosheet assembled ZnO architectures. Such excellent formaldehyde gas sensing performances are predominantly attributed to unique porous-nanosheet constructed three dimensional hierarchical structures, providing beneficial conditions for gas diffusion/adsorption, surface reaction and electron transfer.