Low temperature synthesis of δ-Bi2O3 solid spheres and their conversion to hierarchical BiOI nests via the Kirkendall effect

The Kirkendall effect has gained intense attention and wide acceptance in nanoscience and nanotechnology because it can result in porosity or deformation in the case of the alloying or oxidation of metals. In this work, we report a facile approach to prepare δ-Bi2O3 solid spheres and further convert them to hierarchical BiOI nests for the first time through a solvothermal reaction at low temperature. The δ-Bi2O3 and BiOI samples obtained were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The formation mechanism has been proposed by emphasizing the Kirkendall effect. We also found that the template of δ-Bi2O3 solid spheres was initially formed by surfactant oleylamine induction. Anion exchange has been confirmed to occur in the reaction involving the Kirkendall effect.