Surface Structure Engineering of Nanosheet-Assembled NiFe(2)O(4) Fluffy Flowers for Gas Sensing

In this work, we present a strategy to improve the gas-sensing performance of NiFe(2)O(4) via a controllable annealing Ni/Fe precursor to fluffy NiFe(2)O(4) nanosheet flowers. X-ray diffraction (XRD), a scanning electron microscope (SEM), nitrogen adsorption–desorption measurements and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystal structure, morphology, specific surface area and surface structure. The gas-sensing performance was tested and the results demonstrate that the response was strongly influenced by the specific surface area and surface structure. The resultant NiFe(2)O(4) nanosheet flowers with a heating rate of 8 °C min(−1), which have a fluffier morphology and more oxygen vacancies in the surface, exhibited enhanced response and shortened response time toward ethanol. The easy approach facilitates the mass production of gas sensors based on bimetallic ferrites with high sensing performance via controlling the morphology and surface structure.