LAUSR

Abstract Synthesis, characterization of Co 3 O 4 and Ag-Co 3 O 4 composites and evaluation of their photo-catalytic activities towards photo-degradation of aqueous solution of rhodamine B dye under irradiation of visible light have been described in this paper. Co 3 O 4 was prepared by solid phase mechano chemical process using Co(NO 3 ) 2 ·6H 2 O and NH 4 HCO 3 as precursor materials. Ag was deposited on Co 3 O 4 from AgNO 3 using Calotropis gigantea extract as reducing agent. XRD, SEM and FTIR were used for characterization of prepared composites. Photo-catalytic efficiencies of as-prepared Co 3 O 4 and Ag-Co 3 O 4 were evaluated for aqueous phase photo-degradation of rhodamine B. It was found that deposition of Ag on Co 3 O 4 highly enhanced the photo-catalytic activity of Co 3 O 4 . Photo-catalytic degradation followed the Eley–Rideal mechanism. About 100% and 91% photo-degradation of 40 ml dye solution achieved at 313 K in 90 and 120 min over 0.05 g of Ag-Co 3 O 4 as photo-catalyst using 100 and 200 mg·L − 1 as initial concentration of dye respectively.