Impact of Co and Cu co‐doping on the Structural, Electrical, Magnetic and Solar Light Driven Photo‐Catalytic Properties of NiFe2O4 Nano‐crystals for Crystal Violet Dye Removal

Abstract

AbstractHerein, we have synthesised cobalt (Co) and copper (Cu) co‐doped Ni‐ferrite Ni1‐xCoxFe2‐yCuyO4 nanocrystals (NCs) via the facile micro‐emulsion method. The materials were analysed for various physio‐chemical characterizations to investigate the co‐doping (Co and Cu) effects on magnetic, structural, electrical, photo‐catalytic properties. The structural analysis via Fourier Transform Infrared spectroscopy (FTIR) and X‐rays diffraction (XRD) showed the successful fabrication of Co and Cu co‐doped materials with cubic spinel geometry having a single phase, the crystallite size was observed in 15 to 24 nm range. The electrical response measured using current‐voltage (I–V) analysis showed good electrical features, the electrical resistivity declined from 6.85×107 Ohm.cm for un‐doped materials to 0.04×107 Ohm.cm for co‐doped materials, which was accredited due to the synergistic effects of Co and Cu metal cations in co‐doped Ni‐based ferrite structures. Magnetic investigation using VSM analysis showed increased saturation magnetization (Ms 31.32 to 50.75 emu/g) and coercivity (218.76 to 406.82 Oe) because of the higher magnetic responses of Co2+ions in the co‐doped spinel ferrite NCs. BET surface‐area analysis showed good porosity for co‐doped materials with an increased surface area of 52 to 104 m2/g on co‐doping. The Tauc's plot described the decline of band‐gap energies value (Egs) (1.99 eV) in co‐doped (x=y=0.56) materials as compared to (2.16 eV) of the un‐doped NiFe2O4 materials, which is due to more electrical responses of Co and Cu co‐dopant cations that possess higher energy levels, which can stabilize the charge carrier‘s species. Furthermore, the photo‐degradation using solar light showed good removal of crystal violet (CV) dye, which was almost 94.14 % by co‐doped material; however, by un‐doped material, it was 38.044 %. The scavenger experiment shows that the (OH⋅) hydroxyl radicals and (e−/h+) species play a prime role in the degradation of CV dye. Recycling and recoverability tests for five cycles’ exhibited outstanding stability of the photocatalyst with only 1.7 % losses in activity. Overall, our results showed that co‐doped Ni1‐xCoxFe2‐yCuyO4 NCs materials exhibited enhancement in the magnetic, electrical, photo‐catalytic properties and a decline in band‐gap energy values as compared to un‐doped NiFe2O4, which might have potential use in magnetic and electrical devices as well as solar‐driven photo‐catalyst materials for the remediation of environmental pollution.