title: Nickel-doped cobalt ferrite nanoparticles: efficient catalysts for the reduction of nitroaromatic compounds and photo-oxidative degradation of toxic dyes.
abstract: This study deals with the exploration of NixCo₁-xFe₂O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) ferrite nanoparticles as catalysts for reduction of 4-nitrophenol and photo-oxidative degradation of Rhodamine B. The ferrite samples with uniform size distribution were synthesized using the reverse micelle technique. The structural investigation was performed using powder X-ray diffraction, high-resolution transmission electron microscopy, energy dispersive X-ray and scanning tunneling microscopy. The spherical particles with ordered cubic spinel structure were found to have the crystallite size of 4-6 nm. Diffused UV-visible reflectance spectroscopy was employed to investigate the optical properties of the synthesized ferrite nanoparticles. The surface area calculated using BET method was found to be highest for Co₀.₄Ni₀.₆Fe₂O₄ (154.02 m(2) g(-1)). Co₀.₄Ni₀.₆Fe₂O₄ showed the best catalytic activity for reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 as reducing agent, whereas CoFe₂O₄ was found to be catalytically inactive. The reduction reaction followed pseudo-first order kinetics. The effect of varying the concentration of catalyst and NaBH₄ on the reaction rates was also scrutinized. The photo-oxidative degradation of Rhodamine B, enhanced oxidation efficacy was observed with the introduction of Ni(2+) in to the cobalt ferrite lattice due to octahedral site preference of Ni(2+). Almost 99% degradation was achieved in 20 min using NiFe₂O₄ nanoparticles as catalyst.
authors.affiliation: Department of Chemistry, Panjab University, Chandigarh, India-160 014. chinu.thapar@gmail.com ankigoyal10@gmail.com sonal1174@gmail.com.
authors.forename: Charanjit
authors.initials: C
authors.lastname: Singh
authors.forename: Ankita
authors.initials: A
authors.lastname: Goyal
authors.forename: Sonal
authors.initials: S
authors.lastname: Singhal
mesh_terms: D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D008027:Light; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009532:Nickel / Q000737:chemistry*; D009596:Nitrophenols / Q000737:chemistry; D010084:Oxidation-Reduction; D010316:Particle Size; D010782:Photolysis / Q000528:radiation effects; D012235:Rhodamines / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D004396:Coloring Agents; D005290:Ferric Compounds; D009596:Nitrophenols; D012235:Rhodamines; C001215:ferrite; D003035:Cobalt; D009532:Nickel; C029773:rhodamine B; C024836:4-nitrophenol