Synthesis of rod-like mesoporous γ-Al2O3 by an ionic liquid-assisted sol-gel method

Uniform rod-like mesoporous alumina has been successfully synthesized by an ionic liquid-assisted sol-gel method. The result shows that the morphology of the alumina is dependent on the molar ratio of [Bmim]PF6 to aluminum isopropoxide and the uniform alumina rods with the diameter of 200-400 nm and the length of 2-5 μm can be fabricated at the [Bmim]PF6/aluminum mole ratio 0.18. The hydrogen bond-co-π-π stack mechanism is used to explain the formation of the [Bmim]PF6/aluminum hydroxide hybrids rods. We believe that the ionic liquid plays the role of a capping agent in inhibiting the side growth of the [Bmim]PF6/aluminum hydroxide hybrids through the hydrogen bonds between PF6− and aluminum hydroxides, resulting in the construction of final alumina rods.