Characterization of SiO2/Ag composite particles synthesized by in situ reduction and its application in electrically conductive adhesives

• SiO2/Ag composite particles were prepared via a novel and facile approach.
• The silver shell thickness of SiO2/Ag particles was controlled by the reaction conditions.
• SiO2/Ag particles had core–shell morphology and the silver nanoparticles had FCC structure.
• The synthetic mechanism of SiO2/Ag composite particles was discussed.
• Small content SiO2/Ag improved the electrical bulk resistivity and tensile shear strength.

In the study, SiO2/Ag composite particles with silver coating onto the surface of silica have been successfully prepared via a novel and facile approach (Oxidation–Reduction Method). In this approach, the SiO2 particles were first modified with 3-ammoniatriethoxysilane (APTES) and glyoxalic acid (GA) through two-step reaction, the aldehyde group (CHO) were anchored onto the surfaces of silica spheres via electrostatic attraction, these [Ag(TEA)2]+ ions in the solution were then reduced by the CHO and coated onto the surface of silica to obtain SiO2/Ag composite particles. The effects of the reaction conditions on silver content and synthetic mechanism had also been discussed. The structure, morphology and optical properties of the SiO2/Ag composite particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis spectroscopy. The results showed the surface of SiO2 was surrounded by pure silver nanoparticles, and the silver nanoparticles had face-centered-cubic structure, the SiO2/Ag composite particles with core–shell morphology and special optical properties. And the small content SiO2/Ag composite particles applied in electrically conductive adhesives (ECAs) improved the electrical bulk resistivity and tensile shear strength.

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