Síntesis de Nanoestructuras híbridas Sílica/Oro?

Córdoba

Congreso; Congreso internacional de metalurgia y materiales, 16º SAMCONAMET; 2016

Hybrid nanostructures (NEs) which consist in an oxide substrate decorated with noble metal nanoparticles (NPs) are catalytic devices of great interest since the oxide (stable and inexpensive material) is used as support of the catalytically active material (Au, Ag), generally more expensive. For the synthesis of these NEs is necessary to carry out the heterogeneous nucleation of the noble metal on the oxide substrate surface, however, this process is disadvantaged by low adhesion forces between these materials. One of the mostused strategies for preparing these NEs is the use of bridges molecules capable of forming chemical bonds between the substrate and NPs [1]. Au(OH)3 deposition on oxides and its subsequent calcination [2] is another method employed for producing this type of NEs. In this work, a new method for decorating silicamicroparticles (SiO2MPs) with gold nanoparticles (AuNPs) from Au(OH)3 is reported. This method consists in a single synthetic step without using functionalization or calcination resulting in a considerable simplification of the synthesis.Our studies indicate that aqueous colloids of Au(OH)3 decompose at room temperature generating AuNPs. This process is accelerated by temperature and the medium polarity decrease, producing AuNPs of differentsizes and colloids with different stabilities. Based on this reaction, hybrid NEs can be obtained carrying out the Au(OH)3 precipitation on SiO2MPs and its subsequent thermal decomposition to produce AuNPs directly adhered to the substrate. The strategy is based on the assumption that the Au(OH)3 has a greater adhesion to the substrate (SiO2) than the one that metallic Au exhibits. The results show that the control of synthetic variables allows Au(OH)3 nucleation happens heterogeneously on SiO2MPs.