Room Temperature Synthesis, Growth Mechanism, Photocatalytic and Photoluminescence Properties of Cadmium Molybdate Core−Shell Microspheres

In this paper, we report the first synthesis of homogeneous core−shell CdMoO 4 microspheres on a large scale by a facile aqueous solution route with the assistance of sodium dodecyl sulfate (SDS) at room temperature. The as-synthesized product is characterized by X-ray diffraction pattern, scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, UV−vis absorption spectroscopy, and photoluminescence spectroscopy. The core−shell microspheres have an average diameter of about 4 μm and the shell has a uniform thickness of about 200 nm. The shell is composed of single-crystalline nanoparticles 50 nm in size. The effect of various reaction conditions on the morphology and size of CdMoO 4 products is investigated. The results show that different kinds of surfactants, the concentration of SDS, and reaction times are crucial factors for the formation of core−shell CdMoO 4 microspheres. A possible three-step growth mechanism is presented for the formation of homogeneous core−shell CdMoO 4 microspheres. The calcined core−shell CdMoO 4 microspheres at 500 °C for 2 h exhibit an excellent photocatalytic activity in the degradation of rhodamine B (RhB) under UV light irradiation. The photodegradation of RhB fits the first-order kinetics with K of 0.048 and 0.013 min −1 for the calcined and uncalcined core−shell microspheres, respectively. Photoluminescence measurement shows a strong and broad blue emission peak of 354 nm for the core−shell CdMoO 4 microspheres. The successful synthesis of core−shell CdMoO 4 microspheres may provide some insight into the design of homogeneous core−shell structures of molybdates for potential applications in photocatalysts and optical devices.