Cd-Gd-Doped Nickel Spinel Ferrite Nanoparticles and Their Nanocomposites with Reduced Graphene Oxide for Catalysis and Antibacterial Activity Studies

Abstract During the past few decades, rapid industrializations of the world communities and over use of antibiotics in the medical field have badly influenced our natural ecosystem. Now, these ever-worsening issues have succeeded in drawing the attention of the researcher communities. In this connection, we have fabricated binary metal substitutes nickel ferrite (Ni0.96Cd0.04Gd0.04 Fe1.96O4, NCGF) and its nanocomposite with r-GO via wet chemical method. The photocatalytic and antibacterial aptitude of the fabricated samples has been tested and compared by using organic pollutants (Methylene Blue and Rhodamine-B) and bacterial strains (Escherichia coli and Staphylococcus aureus), respectively as a representative. The nanocomposite shows better photocatalytic and antibacterial aptitude than that of pristine NCGF. More precisely, the NCGF/r-GO heterojunctions based photocatalyst degrade 92.27% methylene blue (MB) dye and 53.18% Rhodamine-B (Rh-B) dye under visible light irradiation. In comparison, the NCGF photocatalyst degrades just 20.25% MB and 11.93% Rh-B dye under the same conditions. The higher activity of NCGF/r-GO photocatalyst is a credit to the suppression in the recombination process of the charge carriers caused by the addition of r-GO in the NCGF matrix. Moreover, the NCGF/r-GO photocatalyst retains 92% of its initial catalytic efficiency even after 5-recycles that indicate its higher stability and good reusability. Additionally, the NCGF/r-GO sample exhibit superior antibacterial aptitude than that of the pristine NCGF sample toward the E. coli and S. aureus bacteria. In fact, the primary constituent of the bacterial cell wall are organic compounds, lipopolysaccharide and peptidoglycan, that are also labile to degrade via photo-induced reactive oxygen species ( H O • , O ¯ 2 • & H 2 O 2 ). The leakage of K+ ions from the raptured cell wall, stop the crucial cell functions that result in the death of the whole bacterial cell. This work offers new insights for the fabrication of substituted ferrites nanomaterials for environmental protection and ecological safety.