The application of inorganic nanocrystals (NCs) in catalysis has attached a great deal of attention over the last years. The use of these nanomaterials offers several advantages, such as unusual (photo)catalytic properties and high surface-area-to-volume ratio.Unfortunately, implementation of such nanomaterials, especially in catalysis and absorption, is not easy, as it often entails a strong tendency of NCs to form large agglomerates with irregular structureand limited porosity. In this context, new strategies to access NC-based porous networks with accessible porosity at the nanometer scale are necessary.
In this presentation we demonstrate that ordered 3D mesoporous networks, which comprise well-defined interconnected metal oxide or metal sulfide NCs, can be prepared through a polymer-templated aggregating assembly of ligand-stabilized nanoparticles.This method involves assembly of soluble nanobuilding blocks into various mesoscopic structures with the aid of amphiphilic surfactants or block copolymers. We have chosen to explore the assembly of BiFeO3, γ-Fe2O3 and CdS mesostructures because of their ensuing magnetic, electronicand photocatalytic properties. The resulting self-assembled materials that obtained after template removal impart the unique combination of catalytic activity of inorganic NCs and 3D open-pore structure, high surface area and uniform pores of mesoporous structure. We show that the pore surface of these materials is active and accessible to incoming molecules, exhibiting high catalytic activity and stability, for instance, in the reduction of 4-nitrophenol into 4-aminophenol, and selective reduction of aryl and alkyl nitro compounds with methyl hydrazine. We demonstrate through appropriate selection of the synthetic components that our method is general to prepare ordered 3D mesoporous networks from inorganic NCs with various sizes and compositions.