Formation of CdMoO4 porous hollow nanospheres via a self-assembly accompanied with Ostwald ripening process and their photocatalytic performance

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A simple direct precipitation process in an aqueous solution at room temperature has been developed for the synthesis of monodispersed CdMoO4 porous hollow nanospheres (PHNs). The obtained CdMoO4 PHNs have an average diameter of ∼500 nm and the shell is constructed from nanoparticles with an average diameter of ∼40 nm. The effects of the concentrations of the reaction reagents, pH value and reaction duration have been systematically studied. The formation mechanism of the CdMoO4 PHNs is related to a self-assembly process accompanied with an Ostwald ripening process, during which the CdMoO4 solid nanospheres are first formed through the self-assembly of CdMoO4 nanoparticles and then gradually developed into porous nanospheres with hollow interiors by an Ostwald ripening process. An optical adsorption investigation shows that the CdMoO4 PHNs exhibit a strong absorption peak in the wavelength of 230–365 nm, centered at 256 nm. The photocatalytic activities of the CdMoO4 samples for the degradation of Rhodamine B (RhB) under UV light were studied. The CdMoO4 PHNs calcined at 300 °C for 2 h exhibit excellent photocatalytic efficiency for the degradation of RhB under UV light, which is up to 97% within 40 minutes. The high photocatalytic performance of the CdMoO4 PHNs is associated with the well-crystallized structure and plenty of nanopores which exist in the spheres, serving as transport paths for small molecules.