Synthesis and Photocatalytic Activity of Single-Crystalline Hollow rh-In2O3 Nanocrystals

Abstract

We report here for the first time the hollow, metastable, single-crystal, rhombohedral In₂O₃ (rh-In₂O₃) nanocrystals synthesized by annealing solvothermally prepared InOOH solid nanocrystals under ambient pressure at 400 °C, through a mechanism of the Kirkendall effect, in which pore formation is attributed to the difference in diffusion rates of anions (OH^– and O^2–) in a diffusion couple. The InOOH solid nanocrystals were prepared via a controlled hydrolysis solvothermal route by using In(NO₃)₃·4.5H₂O as a starting material and glycerol–ethanol as a mixed solvent. The glycerol–ethanol mixed solvent plays a key role on the formation of the intermediate InOOH, thus the final product of rh-In₂O₃. The as-synthesized In₂O₃ nanocrystals present excellent photocatalytic degradation of rhodamine B (RhB) and methylene blue (MB) dyes, which present ∼92% degradation of RhB or MB after 4 or 3 h reaction in the presence of the as-synthesized In₂O₃ nanocrystals, respectively.