Structural, morphological and photocatalytic properties of Bi–Mg–Cu ferrites: Influence of the Bi: Fe ratio

Abstract

Rhodamine B (RhB) dye is an exceedingly dangerous pollutant. So, this study described an effective synthesis of pure and Bi3+ doped Mg–Cu nanophotocatalysts (MCBF) to facilitate the disposal of this harmful pollutant. We studied their structural, morphological, optical, and photocatalytic degradation characteristics. The XRD results of all the prepared photocatalysts confirmed their spinel structure without any impurities. Three justifications for why the lattice parameters of these nanoferrites have a peculiar behavior. The crystallite size has unsteadied behavior; within the range of 29.75–44.87 nm, as determined by the Williamson-Hall approach. The lattice parameter has a distinctive behavior; decrement from 8.3168 Å for MCBF0 to 8.3037 Å for MCBF2 and increment for the nanoferrites MCBF3 (8.3448 Å) and MCBF4 (8.3852 Å) and decreased again for the nanoferrite MCBF5 (8.3448 Å). The STEM graphs demonstrated the agglomeration of nanosized, spherical, and homogeneous-shaped particles. The optical band energy of all the MCBF nanoferrites was in the visible light range of 2.009–2.031 eV. The nanoferrites MCBF0 and MCBF4 have the highest energy gap (2.031 eV), whereas the nanoferrite MCBF5 has the lowest (2.009 eV). Although the modification of the energy gap of MCBF nanoferrites by Bi doping was not large, the photocatalytic activity of MCBF nanophotocatalysts was improved by substituting bismuth ions. In particular, MCBF5, with the highest bismuth content, gave the supreme RhB degradation of 95.81%, with a higher ratio of 245.39% than the pure Mg–Cu ferrite sample. The MCBF5 catalyst showed excellent stability under visible light irradiation across all cycles, 95.81, 95.64, 95.28, 95.04, and 94.89%. Therefore, Mg0·5Cu0·5Bi0·1Fe1·9O4 nanoferrite is a suitable option for RhB degradation under sunlight and may function as a likely catalyst in wastewater purification.