Stable photoluminescent ZnO@Cd(OH)2 core–shell nanoparticles synthesized via ultrasonication-assisted sol–gel method

Core–shell structured ZnO@Cd(OH)2 nanoparticles with stable and improved luminescence have been prepared successfully via a facile ultrasonication-assisted sol–gel method. Their composition and structure have been confirmed by high resolution transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and infrared spectra. The size of the nanoparticles decreases gradually along with the increase in the shell thickness, indicating that Cd(OH)2 shells can hider ZnO cores growth and aggregation effectively. The as-prepared core–shell nanoparticles can be stored at room temperature for several weeks without luminescence efficiency reduction, and they are quite stable at elevated temperatures or in moderate alkaline solutions due to the protection of the Cd(OH)2 shell.

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► ZnO@Cd(OH)2 core–shell quantum dots are prepared via a sonochemical sol–gel method.
► These QDs are stable during storage, at high temperature and in alkaline solutions.
► Our method is rapid, simple, and effective for synthesizing highly luminescent QDs.