Various self-assembled three-dimensional hierarchical architectures of La2(MoO4)3: controlled synthesis, growth mechanisms, luminescence properties and adsorption activities

Abstract

Tetragonal La₂(MoO₄)₃ with various novel and complex 3D hierarchical architectures self-assembled from different building blocks were successfully synthesized by a hydrothermal method in EDTA-mediated processes. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) were employed to characterize the as-obtained products. It was found that morphology modulation could be easily realized simply by changing the amount of EDTA introduced into the reaction system. The amount of EDTA not only affected the substructures of the hierarchical structures, but also determined the size distributions of the final products. The formation mechanisms for different hierarchical architectures were proposed on the basis of a series of time-dependent experiments. An investigation on the photoluminescence (PL) properties of La₂(MoO₄)₃:Eu with different morphologies revealed that the optical properties were strongly correlated with the morphology and size. Furthermore, as highlighted by the fascinating hierarchical structures of La₂(MoO₄)₃, the potential application of La₂(MoO₄)₃ as an absorbent in water treatment was also investigated for the first time. Possible reasons responsible for the differences in photoluminescence behaviors and absorption activities of different hierarchical architectures were discussed.