Effect of SiCl4 on the preparation of functionalized mixed-structure silica from monodisperse sol–gel silica nanoparticles

•Functionalization of nanosilicas with Si–Cl by hydrolysis of SiCl4 sol–gel process.•Growth of monodisperse functionalized nanosilicas on a micrometric silica particle.•Generating of functional mixed structured silica with incorporation of Cl on the surface.•Effect SiCl4 concentration on hierarchical and morphological structure was studied.•Enhancement the textural and structural properties of Sylopol, commercial support.

Mesoporous functionalized nanoparticles (nanosilica) and functionalized mixed-structure silica with surface Si–Cl groups were prepared via a SiCl4 hydrolysis base-catalyzed sol–gel process. This study presents hierarchically structured systems formed via growth and self-assembly of functionalized silica nanospheres on the surface of Sylopol-948, generating functionalized mixed-structure silica. The fabricated materials were characterized by nitrogen adsorption, small angle X-ray (SAXS), dynamic light scattering (DLS), zeta potential (ZP), infrared spectroscopy (FT-IR), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDX). The incorporation of Si–Cl groups (0.02–0.43 Cl/Si) on the surface—to functionalize the nanoparticles and modify their properties—was confirmed by SEM–EDX and cyclic voltammetry. In functionalized mixed-structure silica, the SBET value (567 m2/g) increases, particle size (13.6–17.2 nm) decreases and surface charge (−9.0 mV) diminishes as SiCl4 concentration increases. In functionalized nanosilica, a lower SiCl4 concentration results in a higher SBET value (730.6 m2/g), smaller nanoparticle size (6.0–12.4 nm) and higher surface charge (−22.9 mV). These materials were experimentally compared and found to demonstrate improved characteristics compared to Stöber nanosilica, non-functionalized mixed-structure silica, and Sylopol-948.

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