Structural biological electrical and catalytic activity of Mg doped Ni nano chromites synthesized through citrate gel method

Abstract

In this study, Ni_1-xMg_xCr₂O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) spinel ferrites were synthesized using the citrate gel method, and their optoelectronic properties were investigated. The structural, morphological, optical, photocatalytic, and dielectric properties were systematically examined. X-ray diffraction (XRD) confirmed the formation of a single-phase spinel structure, with lattice parameters varying according to Mg content. The crystalline size of the samples ranged from 6.7 to 20.23 nm, with the smallest crystalline size observed for Ni_0.2Mg_0.8Cr₂O₄ nanochromites. Scanning electron microscopy (SEM) revealed a uniform grain distribution and morphology changes with increasing Mg concentration. Fourier transform infrared spectroscopy (FTIR) provided insights into the metal-oxygen bond vibrations within the spinel structure. UV-visible spectroscopy showed the material’s optical band gap, which is crucial for its photocatalytic performance. The photoluminescent (PL) analysis demonstrated that all samples exhibited broad near-band-edge emission in the visible wavelength region (~570 nm). Photocatalytic activity was assessed by the degradation of methylene blue and acid red dyes under UV light, demonstrating enhanced activity with Mg substitution. Cytotoxicity analysis against the Hela cell line (a human cervical cell) was conducted to assess the anticancer activity with IC50 values calculated from the MTT assay. Antibacterial and anti-fungal activity against gram positive and gram-negative bacterial pathogens and two fungal pathogens was studied. The frequency dependence of the dielectric constant, loss, and AC conductivity was examined from room temperature to 400 °C. The dielectric constant and loss results for the samples aligned with the Maxwell–Wagner model, which is grounded in interfacial polarization, consistent with Koops’ theory. Dielectric studies indicated significant dielectric constants and loss tangents, highlighting the material’s potential for electronic applications.

Graphical Abstract