A surfactant-free strategy for controllable growth of hierarchical copper oxide nanostructures

A surfactant-free strategy for controllable growth of various hierarchical CuO nanostructures was successfully achieved through a facile, one-pot solution-phase transformation of CuxMy(OH)(z) (M = SO42-, Cl-, NO3- and CH3COO-) precursors method without extra heat treatment in air. The formation of CuO nanostructures here is essentially determined by the species of CuxMy(OH)(z) precursors. The nanoparticle aggregation with controllable shapes can be formed under different concentrations of reactants. Hierarchical CuO nanoflowers with different branched building blocks were prepared by the transformation of Cu-4(SO4)(OH)(6) precursors. Hierarchical CuO nanospindles and nanoplates were fabricated by the transformation of Cu-2(OH)(3)NO3 precursors. Hierarchical CuO nanoplate assemblies and nanoplates were synthesized by the transformation of Cu7Cl4(OH)(10)H2O and C(8)H(6)Cu(3)O(10)4H(2)O precursors, respectively. Structural and morphological evolutions were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and field-emission scanning electron microscopy (FESEM). This study is of great importance in controllable synthesis of surfactant-free CuO nanostructures, because it not only enriches the family of CuO architectures but also offers a good chance to understand the nature of the solution-phase precursor transformation method for synthesizing CuO nanostructures. Significantly, it is believed that this surfactant-free solution-phase precursor-driven synthesis of nanostructures presented here might provide a green approach to design and growth other well-defined metal oxide nanostructures.