Abstract: Ag nanoparticles were prepared on SiO₂ surface at different temperatures via adsorption phase reaction technique. The influence of temperature on adsorption of NaOH, reduction reaction of Ag and morphology of Ag nanoparticles was studied. Measurement results of adsorbed NaOH indicate that adsorption of NaOH needed more time to reach equilibrium with temperature increasing. The reaction of NaOH with Si—O—Si became more rapid due to increase of temperature, which resulted in little change of equilibrium percentage of NaOH with decrease of adsorption layer. The reduction reaction of Ag was characterized by UV-Vis adsorption spectra. The results suggest that when temperature reached 40 ℃, induction time, concentration and size distribution of Ag nanopartcles all changed greatly. When temperature increased to 40 ℃, there was great glomeration in morphology of sample analyzed by TEM and a sharp increase appeared in grain size gained by XRD. Adsorption layer was destroyed with temperature increasing, which resulted in the generation region of Ag nanoparticles transferred from adsorption layer to SiO₂ surface. Moreover this change of reaction region resulted in the great change of reduction reaction mechanism of Ag and morphology of particles.

Key words: Adsorption phase reaction technique, Ag/SiO₂, Temperature, Change of reaction region