Ferromagnetic nature and solar-induced fast catalytic properties for green environment: New Fe/Cu/V-Mn₃O₄ p-type compounds

Nanocrystalline pure, Fe-Cu and Fe-V substituted Mn 3 O 4 semiconductors were produced via a coprecipitation process as advanced magnetic compositions and efficient photocatalysts for the elimination of industrial Congo red (CR) waste. The X-ray diffraction (XRD) results confirmed that all samples have a tetragonal structure of Mn 3 O 4 (hausmannite, I41/amd). The band gap energy of pure, Fe-Cu, and Fe-V co-doped Mn 3 O 4 nanostructures were measured to be 2.1, 1.78, and 1.65 eV, respectively. The valence states of Cu, Fe, and V cations were confirmed by the X-ray photoelectron spectroscopy (XPS) as +2, +3, and +4, respectively. The magnetic analysis of Fe-Cu and Fe-V co-doped Mn 3 O 4 powders gives room temperature hysteresis ferromagnetic curves. The obtained magnetic data demonstrated a spin-ferromagnetic order as Fe 3+ -Cu 2+ and Fe 3+ -V 4+ cations replaced Mn-sites inside Mn 3 O 4 structure with measured saturation magnetization of 1.49 and 1.67 emu/g as well as coercivity of 1668 and 378 Oe, respectively. Both Fe 3+ -Cu 2+ and Fe 3+ -V 4+ mixtures, as well as the oxygen vacancies, are accountable for the ferromagnetic nature according to the bound magnetic polarons (BMPs) visualization. The Fe 3+ -Cu 2+ substituted Mn 3 O 4 semiconductor as a photocatalyst revealed a rapid solar photo-removal activity of 98% after 25 mins when applied to remove CR as industrial waste.