Ag/SiO 2 catalysts prepared via γ-ray irradiation and their catalytic activities in CO oxidation

Abstract

We explored the synthesis of Ag/SiO 2 catalysts via γ-ray irradiation at room temperature. AgNO 3/SiO 2 prepared by the conventional incipient wetness impregnation method was employed as the precursor. Ag/SiO 2 catalyst prepared by calcining AgNO 3/SiO 2 at 500 °C was also prepared for comparison. The Ag/SiO 2 catalysts were characterized with X-ray diffraction, X-ray photoelectron spectroscopy, and diffuse reflectance UV–vis spectrum, and their catalytic activities towards CO oxidation were also tested. γ-Ray irradiation successfully reduced Ag + anchored on SiO 2 into silver nanoparticles at room temperature. Existence of excess water during the γ-ray irradiation led to the formation of larger silver nanoparticles. These catalysts behaved differently in CO catalytic oxidation. Compared with Ag/SiO 2 prepared by calcination that showed a certain low temperature catalytic activity but poor stability, Ag/SiO 2 prepared by room temperature γ-ray irradiation showed an inferior low temperature catalytic activity and a better stability. The different catalytic behavior is associated with the various crystalline sizes of silver nanoparticles in Ag/SiO 2 prepared by different methods.