In view of the existing problems that the particle size of prepared powders is large, AgO content is low, the requirement for equipment is high and waste solution caused environmental pollution is produced in preparation process, in this paper ultrafine silver peroxide powders were prepared by chemical oxidation method using pollution-free ozone as oxidant. Effects of factors such as reaction temperature, initial pH value and ozone input time on silver peroxide content were studied. The prepared products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and shake-flask method. The results show that ultrafine powders with a AgO content of 83.56%, a platy morphology and a thickness around 100 nm are prepared in conditions of reaction temperature 45 ℃, initial pH value 14, ozone input time 5 h. There are only Ag and O elements in powders which silver exists mainly in the forms of monoclinic AgO and little cubic Ag₂O. AgO possesses strong antibacterial ability. When the concentration of antibacterial agent is 1 mg•L^－1 and acting time is 30 min, the bactericidal rates of powders with a AgO content of 83.56% against S.aureus and E.coli both exceed 99.9%. And in the same condition, the bactericidal rates of AgO are 7 times higher than that of Ag₂O in 5 min.

Key words: chemical oxidation, ozone, AgO, antimicrobial activity