Ultrathin ZnO membranes a few atomic layers in thickness

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 \(\left\langle {01 \bar 10} \right\rangle\), which was perpendicular to [0001] growth direction in a typical hydrothermal synthesis. The growth mechanism of the membranes was also discussed.