Cobalt and holmium co-doped nickel ferrite nanoparticles: synthesis, characterization and photocatalytic application studies

Abstract

Herein, nickel ferrite-based photocatalysts with enhanced light utilizing electrical charge transport properties have been reported for environmental remediation applications. The cobalt and holmium co-doped nickel ferrite [Ni _{1− x} (Co) _x Fe _{2− y} (Ho) _y O ₄] nanoparticles and bare nickel ferrite (NiFe ₂O ₄) nanoparticles have been prepared via surfactant-supported wet-chemical techniques. The as-prepared ferritic photocatalyst’s structural, morphological, and light harvesting features have been examined in detail using well-known physical, electronic, and optical methods. The co-doped ferrite photocatalyst’s tuned structural features enable it to absorb maximum wavelengths from the U.V. and visible regions. This is because the co-doped Ni _{1− x} (Co) _x Fe _{2− y} (Ho) _y O ₄ optical band gap is 1.73 eV; hence, the wavelength from the visible part possesses sufficient energies to trigger the electronic excitation in co-doped ferrite photocatalysts. Moreover, the co-doping-induced structural defects in the ferrite photocatalyst. These defects act as a reservoir for the charge species, mainly electrons, so the process of charge recombination is almost hampered for the Ni _{1− x} (Co) _x Fe _{2− y} (Ho) _y O ₄ photocatalyst. In application terms, the photomineralization capabilities of doped and bare ferrite photocatalysts have been explored using crystal violet (CV) dye. The comparative photocatalytic evaluation of both nickel ferrite-based photocatalysts shows that co-doped ferrite degraded 96.02 % of CV dye. In comparison, the undoped one only degraded 64.84 % after 80 min of W-lamp light exposure. The results demonstrated that the Ho and Co co-doped ferrite photocatalyst exhibits excellent photocatalytic activity, suggesting its potential for environmental remediation applications in textile industrial discharges.