Synthesis of corundum-type In2O3 porous spheres and their photocatalytic properties

Abstract

In this work, polycrystalline indium oxyhydroxide (InOOH) porous spheres were synthesized through a mixed solvothermal method in the presence of sodium citrate (Na₃cit) as a structure-directing agent. Corundum-type In₂O₃ porous spheres were obtained via annealing InOOH precursors at 400 °C for 2 hours. The samples were characterized by means of X-ray powder diffraction, thermogravimetric analysis, UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The Ostwald ripening process was proposed as the mechanism for the formation of porous spheres. Photocatalytic activity of the porous h-In₂O₃ spheres was evaluated by degrading rhodamine B (RhB) under ultraviolet (UV) irradiation. The results indicated that the porous h-In₂O₃ spheres possessed superior photocatalytic activity to their counterparts, and could restore 95% of the initial photocatalytic activity after 5 reaction runs.