One-step method for the self-assembly of metal nanoparticles onto facetted hollow silica tubes

An optimized synthetic approach has been developed for the exclusive formation of facetted silica tubes using a simple organic molecule i.e. ammonium tartrate as a template. The synergy of two phenomena: ( a) aggregation of ammonium tartrate and (b) interaction of a hydrolysed TEOS intermediate with the ammonium tartrate aggregate, was achieved under optimized conditions (i.e. 0 degrees C and pH ca. 11) which resulted in the complete formation of facetted silica tubes as the sole morphology. The typical length and width of these facetted tubes were of the order of 60 - 100 mu m and 0.4 - 1.2 mu m, respectively. Furthermore, a novel one-step method has been developed to anchor Au and Ag nanoparticles onto these tubes. This involves surfactant coated nanoparticles and the anchoring does not necessitate the pre-functionalization of the silica walls. The method is fast, economic and in addition it can be adapted for the synthesis of other hybrid nanomaterials.