Manipulating the morphology and textural property of γ-AlOOH by modulating the alkyl chain length of cation in ionic liquid

• γ-AlOOH was the only product in all experiments.
• Different morphology of γ-AlOOH was obtained according to the alkyl chain length.
• The textural property of γ-AlOOH was changed according to the alkyl chain length.
• The possible formation mechanisms for hollow sphere and microflower were proposed.

We demonstrated that the morphology and textural property of γ-AlOOH can be tuned by modulating the alkyl chain length of cation in [Cnmim]+Cl− (n = 4, 8, 16). Using the short alkyl chain length-based [C4mim]+Cl− as the structure-directed reagent, the morphology of γ-AlOOH was not changed and preserved as the hollow sphere structure in all experiments. The specific area and the number of small meso-pores of γ-AlOOH increased with the increase of [C4mim]+Cl− dosage. While, using the larger alkyl chain length-based ionic liquids as the soft-template, such as [C8mim]+Cl− and [C16mim]+Cl−, the morphologies of γ-AlOOH were changed from initiative hollow spheres into the final microflowers. The specific areas of γ-AlOOH firstly increased then decreased with the increase of their dosage. The samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). Furthermore, the possible formation mechanisms of γ-AlOOH have been proposed.

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