In situ synthesis of gold nanoparticles on mesoporous silica surface-functionalized with pyridinium ligands

This paper describes the synthesis of gold nanoparticles on the surface of two types of silica matrices, the disordered mesoporous silica (DMS) and SBA-15, which are chemically functionalized with pyridinium ligand. The adsorption of AuCl₄⁻ occurred through the ion exchange method. The gold nanoparticles were synthesized through the reduction of the adsorbed Au ions on the surface of silica matrices. The silica surface was functionalized with 3-n-propylpyridinium chloride trimethoxysilane, and it was confirmed through ²⁹Si and ¹³C solid-state CP/MAS NMR. Then, gold nanoparticles were in situ synthesized in the hybrid material surface. The DMS-PyClAuX materials exhibited spherical nanoparticles with a maximum average size of 9.6 nm when the highest gold concentration (2.08 wt%) was used. The SBA-PyClAuX materials showed nanoparticles with a maximum average size of 5.5 nm. By comparing the standard deviations observed in the materials of both matrices, we observed that the SBA-15 matrix presented better control of the nanoparticle diameter.