Simultaneous Synthesis of Al-Doped ZnO Nanoneedles and Zinc Aluminum Hydroxides through Use of a Seed Layer

Abstract

Al-doped ZnO nanoneedles with a tip diameter of ∼10 nm and hexagonal zinc aluminum hydroxide were simultaneously synthesized and completely separated in one step. An aqueous solution containing metal ions (Zn2+ and Al3+), in which a Zn-deposited substrate was immersed, was irradiated with microwaves. Al-doped ZnO nanoneedles (average Zn/Al molar ratio of 55.5) grew on the substrate, whereas zinc aluminum layered double hydroxides (average Zn/Al molar ratio of 2.51) grew as homogeneous precipitates in the bulk solution. The 1D Al-doped ZnO nanoneedles had an average length of ∼1.3 μm. The length, diameter, and shape of the nanoneedles were uniform. The 2D hexagonal zinc aluminum hydroxides had lateral dimensions of 500 nm to 1.8 μm and an average thickness of ∼50 nm. Asymmetric partitioning of Zn and Al species was observed in the simultaneous synthesis of these nano/microcrystals.