Facile synthesis of new composite, Ag-Nps-loaded core/shell CdO/Co3O4 NPs, characterization and excellent performance in antibacterial activity

Here, we report for the first time the synthesis of new composite Ag-NPs-loaded core/shell mixed oxides NPs, CdO/Co3O4. First, nano-precursors (1) and (2) consist of mixed (cadmium oxalate/cobalt oxalate) and (silver oxalate/cadmium oxalate/cobalt oxalate), respectively, have been synthesized and characterized. Then, thermal treatment of 1 and 2 at 400 °C resulted in the formation of composites CdO/Co3O4 (3) and Ag-NPs@CdO/Co3O4 (4), respectively. The materials have been characterized by IR, SEM, TEM, TGA and XRD. The morphologies of the materials were described from SEM images. TEM images revealing the formation of core–shell structure with average particles size 5–20 nm. The crystal sizes were calculated from XRD patterns and resulted in 14.21, 14.65, 15.06 and 15.79 nm for 1, 2, 3 and 4, respectively. All the materials undergo tests as antibacterial agents against Gram-positive bacteria (Bacillus subtilis and Enterococcus spp.) and Gram-negative bacteria (E. coli and Pseudomonas aeruginosa). Precursor 2 and composite 4 impart higher inhibition against all the bacterial strains compared to precursor 1 and composite 3