Synthesis of Ag@Co–NiFe ₂ O ₄ /GO nanocomposites for photocatalysis: X-ray peak profiling, electromagnetic and optical properties

This study presents the successful synthesis of Co_0.5Ni_0.5Fe₂O₄ nanoparticles and their composites with silver (Ag) and graphene oxide (GO) using a facile ultrasonic assisted co-precipitation method. Powder X-ray diffraction (PXRD) verified the creation of spinel ferrite structures, integrating Ag nanoparticles and graphene oxide (GO). Crystallite sizes were calculated by detailed X-ray peak profiling using different models including the classical Scherrer method, Munshi-Scherrer method, Williamson-Hall method, size-strain plot method, Halder-Wagner method and conventional Rietveld refinement using GSAS-II software as well as the crystal structure derived from VESTA software. Field emission scanning electron microscopy showed spherical nanoparticles, with energy dispersive X-ray spectroscopy (EDX) verifying the elemental composition. Magnetic analysis showed ferrimagnetic behaviour, with reduced saturation magnetization in Ag and GO-modified samples but increased coercivity for GO-modified system. Optical bandgap analysis <i>via</i> UV-DRS indicated bandgaps ranging from 1.95 to 2.03 eV for Ag and GO composites. Dielectric properties were measured, showing a sharp decrease in the dielectric constant at low frequencies, followed by stabilization. Photocatalytic tests revealed that Ag@Co_0.5Ni_0.5Fe₂O₄/GO achieved the highest methylene blue degradation efficiency (96.59%) under visible light, attributed to enhanced electron-hole separation and silver's plasmonic effects. These results suggest that Co_0.5Ni_0.5Fe₂O₄-based nanocomposites, particularly Ag@Co_0.5Ni_0.5Fe₂O₄/GO, have potential for photocatalytic and environmental remediation applications.