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Functionalization of Flower-Like ZnO Nanostructures With Au@CuO Nanoparticles for Detection of Ethanol

Hierarchical flower-like ZnO nanospheres were synthesized by a facile hydrothermal method using sodium citrate as soft template. The products were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray, inductively coupled plasma atomic emissions spectroscopy, and X-ray photoelectron spectroscopy techniques. The SEM and TEM results showed that the 3D ZnO nanospheres were consisted of 2D ZnO nanosheets. The diameter of the nanospheres was 3-4 μm and the thickness of the nanosheets was 60-70 nm. In order to improve the ethanol-sensing properties, the 3D ZnO nanostructures were functionalized with Au@CuO nanoparticles. Because of the protection of the CuO shell from aggregation, the size of the Au@CuO nanoparticles were smaller than that of the Au nanoparticles after annealing. The sensing response of 0.7% Au@0.3% CuO loaded ZnO was close to that of 1% Au loaded ZnO, and much higher than that of the unfunctionalized ZnO. The good performance was probably attributed to the high intensities of the chemical adsorption oxygen and the active sites of the Au@CuO functionalized ZnO nanostructures.