Micro-lotus constructed by Fe-doped ZnO hierarchically porous nanosheets: Preparation, characterization and gas sensing property

Micro-lotus constructed by porous Fe-doped ZnO nanosheets were successfully prepared by a one-step hydrothermal route. The Fe-doped ZnO with micro-nanostructures shows significantly improved gas response to several reductive gases compared with the undoped ZnO, however, excessive Fe doping suppresses the gas sensing response. Preparation of micro-lotus constructed by hierarchically porous Fe-doped ZnO nanosheets via a facile hydrothermal method is reported here. The products have been analyzed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and high resolution transmission electron microscope (HRTEM). Results showed that the morphology of the sample did not change with the Fe doping amount. The photoluminescence (PL) spectra revealed the existence of oxygen vacancies in the Fe-doped ZnO porous nanosheets, which is beneficial to the adsorption of oxygen and gas response, resulting in the improved performances in the later gas sensing experiments towards several reductive gases. The effect of Fe doping percentage on the gas response has also been investigated. We found that ZnO sample with Fe doping atomic percentage of 1% showed the highest gas sensing performance, while excessive Fe doping in ZnO suppressed the gas sensing response. A possible mechanism of how Fe-doped ZnO-based sensor responses to the target gas is also proposed.