In this paper, well-defined Mg-Al LDHs nanosheets with high yield are prepared by the following sequential procedures: hydrothermal preparation of Mg-Al-CO2−32−3 LDHs, followed by expanding interlayer spacing by NH4NO3 treatment. The results show that the concentration of the layer expansion agent (NH4NO3)3) and the exfoliation solvent play a key role in the exfoliation result. The basal spacing changed from 0.758nm to the range of 0.758–0.895nm when the concentration of NH4NO3 was increased up to 5 M, which infers that the increase of layer space is caused by the synergy of NH+4+4 and NO−3−3. Among the three exfoliation solvents (formamide, N-methyl pyrrolidone and isopropyl alcohol), formamide showed the highest exfoliation effect. From the characteristic XRD patterns, the as-obtained colloidal aggregates of the exfoliated nanosheets do not show the characteristic diffractions of LDHs, while the typical peaks at 10.562∘∘, 20.032∘∘ and 21.185∘∘ assigned to LDHs are observed after drying of the colloidal aggregates. Moreover, a transparent LDH film is also successfully prepared by coating colloidal aggregates of nanosheets on a glass substrate without using any adhesive. The stable film exhibits the strong adsorption ability of Methyl Orange.
