Morphology-controlled ZnO spherical nanobelt-flower arrays and their sensing properties

In this paper, ZnO spherical nanobelt-flowers (the corresponding gas sensor is dp-ZnO-SFF) are obtained by heating Zn5(OH)8Ac2·2H2O (LBZA, layered basic zinc acetate) precursors, and LBZA hierarchical structures with different morphologies are designed and selectively grown by controlling the growth conditions. ZnO products obtained via pyrolysis processes maintain the original morphologies of LBZA precursors without deformation. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction are used to characterize the detailed structures of the as-prepared products. Structure related experiments reveal the unique role of nanobelts and hierarchical flower structures. We conclude that the highly exposed surfaces of nanobelt branches and the 3D porous hierarchical structure of dp-ZnO-SFF provide more pathways for gas diffusion than other samples, which is responsible to its high sensing properties. To avoid the performance degradation caused by structural damage and high temperature treatment of drop-coated method, self-standing LBZA spherical nanobelt-flower arrays film is grown on the substrate. The corresponding ZnO product is directly applied as the sensing film and shows high responses to benzene gas.