Infoscience

Journal article

General Method for the Synthesis of Hierarchical Nanocrystal-Based Mesoporous Materials

Block copolymer templating of inorg. materials is a robust method for the prodn. of nanoporous materials. The method is limited, however, by the fact that the mol. inorg. precursors commonly used generally form amorphous porous materials that often cannot be crystd. with retention of porosity. To overcome this issue, the authors present a general method for the prodn. of templated mesoporous materials from preformed nanocrystal building blocks. The work takes advantage of recent synthetic advances that allow org. ligands to be stripped off of the surface of nanocrystals to produce sol., charge-stabilized colloids. Nanocrystals then undergo evapn.-induced co-assembly with amphiphilic diblock copolymers to form a nanostructured inorg./org. composite. Thermal degrdn. of the polymer template results in nanocrystal-based mesoporous materials. This method can be applied to nanocrystals with a broad range of compns. and sizes, and the assembly of nanocrystals can be carried out using a broad family of polymer templates. The resultant materials show disordered but homogeneous mesoporosity that can be tuned through the choice of template. The materials also show significant microporosity, formed by the agglomerated nanocrystals, and this porosity can be tuned by the nanocrystal size. The authors demonstrate through careful selection of the synthetic components that specifically designed nanostructured materials can be constructed. Because of the combination of open and interconnected porosity, high surface area, and compositional tunability, these materials are likely to find uses in a broad range of applications. For example, enhanced charge storage kinetics in nanoporous Mn3O4 is demonstrated here.

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