Selectively assembled 2D microarrays from binary nanocrystals

Selective self-assembly processes were identified in an aged colloidal dispersion containing CeO₂ cube-like and polyhedral nanocrystals as building blocks, resulting in two types of 2D microarrays. The cube-like nanocrystals were hierarchically self-assembled to form cubic nanoblocks with a mesostructure size of ca. 100 nm and a 2D microarray size of over 100 μm. The hierarchical assembly of the cube-like nanocrystals triggered the direct self-assembly of polyhedral nanocrystals, which then formed 2D microarrays. The hierarchical assembly of nanocrystals with a similar morphology was the dominant assembly process in the colloidal dispersion, and the cube-like nanocrystals tend to assemble through an oriented axis; otherwise, the fusion between the oriented nanocrystals is random.