Silver-doped Co–Mg spinel nanochromites synthesized by citrate gel auto combustion method: Structural, optical, photocatalytic, and biological activities

In the present work silver-substituted cobalt and magnesium chromites of Co 0.25 Mg 0.50 Ag x Cr 2- x O 4 ( x = 0.00–0.25 by 0.05 different variation) were prepared by sol-gel auto-combustion’s technique, using citric acid. Single-phase cubic spinel structure formation and an average crystallite size of synthesized samples was in between 5 and 8 nm were obtained through XRD patterns. The morphology of the chromites was analyzed by the FESEM technique. The existence of Cr, O, Ag, Co, and Mg elemental mappings in the prepared chromites was confirmed by EDS analysis. High-Resolution Transmission Electron Microscopy (HRTEM) images reveal ultra-fine grains with sizes in the nanometer range. The Selected Area Electron Diffraction (SAED) patterns confirm the crystalline nature of the samples, displaying sharp and well-defined diffraction. The spinel chromite structure was confirmed by FT-IR spectra, which gives two vibrational bands attributed to the metal oxide bands of Co and Mg metals. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) revealed negligible weight loss above 500° C, indicating the successful formation of a thermally stable crystalline spinel chromite phase. Optical properties of silver-substituted cobalt and magnesium chromites and bandgap energies of samples are obtained by recording the UV-DRS spectra. Ag-1 and Ag-4 the assessed specific surface areas of the samples were calculated by using the BET technique and gave a value of 77.241 and 98.169 m 2 /g, respectively. The photo-catalytic degradation activity of samples were analyzed by Rhodamine blue (RhB) dye irradiated by Ultra-Voilet light. The scavenger tests indicate that •O 2 - , •OH and h + are majorly active species that enable the effective photodegradation of the RhB dye. The DNA Cleavage properties were studied by using agarose gel electrophoresis technique, DNA binding studies were performed and found the binding mode as intercalative mode. Anti-microbial (bacterial, fungal) and anticancer activity done on synthesized samples, which gives positive results towards bacterial pathogens and fungal pathogens and cytotoxic study was performed on the Hela cell line, Ag-4 (x = 0.15) exhibited superior anticancer activity.