Template Controlled Synthesis (TCS) of size-controlled metal nanoclusters: preparation of nanostructured metals supported by inorganic supports

Strictly size-controlled metal nanoclusters of palladium(0) and gold(0) can be easily formed in the organic component of an organic-inorganic composite between a gel-type resin (DV44) and silica. To this purpose, silica is impregnated at incipient wetness with a solution of the required co-monomers (N,N-dimethylacrylamide, 4-vinylpyridine and N,N′-methylene-bis-acrylamide), which are co-polymerized to give the composite. The silica-supported polymeric framework is then loaded with palladium(II) or gold(III) precursors. Their chemical reduction with aqueous solutions of sodium boronhydride yields the metal nanoclusters. Their size is controlled by the nanomorphology of the polymeric framework, which acts as a template during the nanocluster growth (Template Controlled Synthesis). Upon thermal decomposition of the polymeric template at 600°C under nitrogen, the nanostructured metals are deposited onto the silica surface. In the case of palladium the final step occurs with retention of the original size of the nanoclusters.