For the first time we fabricated ZnO membranes with thicknesses of 2.4 nm by a facile one-pot synthesis in aqueous solution.The crystal analysis revealed that the hexagonal ZnO membranes were about 10 atomic layers in thickness.The ZnO membranes bent,scrolled,intersected with each other,and self-assembled to particles in micrometre size.The hierarchical assemblies showed sponge-like structures with room inside.In the growth process,a cationic polyelectrolyte was utilized to modulate growth behavior of the ZnO crystals.As a result,the preferred growth direction of ZnO membranes is along 0110,which was perpendicular to[0001]growth direction in a typical hydrothermal synthesis.The growth mechanism of the membranes was also discussed. For the first time we fabricated ZnO membranes with thicknesses of 2.4 nm by a facile one-pot synthesis in aqueous solution. Crystal analysis revealed the hexagonal ZnO membranes were about 10 atomic layers in thickness. ZnO films bent, scrolled, intersected with each other, and self-assembled to particles in micrometre size. hierarchical mechanisms showed sponge-like structures with room inside. the growth process, a cationic polyelectrolyte was utilized to modulate growth behavior of the ZnO crystals. As a result, the preferred growth direction of ZnO membranes is along 0110, which was perpendicular to [0001] growth direction in a typical hydrothermal synthesis. growth mechanism of the membranes was also discussed.