INTERFACIAL ELECTRON-TRANSFER IN COLLOIDAL SPINEL IRON-OXIDE SILVER ION REDUCTION IN AQUEOUS-MEDIUM

the redox behavior of spinel iron oxide colloids has been evidenced by studying silver reduction by magnetic using potentiometry, X-ray diffraction and Mösshauer spectroscopy. At pH ≥6, silver reduction involves an interfacial electron transfer without iron desorption, and the Fe3O4 → γ-Fe2O3 transformation. In reverse, the γ-Fe2O3 colloid can be refilled with electrons by FeII adsorption, which results in the growth of a Fe3o4 surface layer. This reduced colloid is much more reactive than the intial Fe3O4 particle. © 1990.