Controllable construction of Cr2O3-ZnO hierarchical heterostructures and their formaldehyde gas sensing properties

The designed Cr2O3-ZnO hierarchical heterostructures have been successfully synthesized by a facile two-step route. The SEM, TEM, XRD and EDS mapping characterizations demonstrate that Cr2O3 nanoparticles are well decorated on surfaces of nanosheet-assembled flowerlike ZnO, constructing three dimensional Cr2O3-ZnO hierarchical heterostructures. Such hierarchical architectures are developed and applied in formaldehyde (HCHO) gas detection. The gas sensing results indicate that Cr2O3-ZnO heterostructures based sensors exhibit superior HCHO gas sensing properties with rapid response/recovery behavior (1 s/5 s) toward 100 ppm formaldehyde (HCHO) gas, and favorable stability and repeatability with the on/off phenomenon when switching between HCHO and air at a optimal working temperature of 220 degrees C. The superior formaldehyde gas sensing performances are predominantly attributed to the appropriate sensitization effect induced by Cr2O3 nanoparticles and the special three dimensional hierarchical architectures. (C) 2018 Elsevier B.V. All rights reserved.