NiCo₂O₄ nanospinel and its catalytic activity for oxidation of Rhodamine B at ambient conditions

Two hetero-bimetallic precursors, [Co(en)₃]₂[Ni(edta)]₃ and [Ni(en)₃][Co(edta)]₂ (en = ethylenediamine and edta⁴⁻ = ethylenediaminetetraacetate anion), were synthesized in an aqueous solution. For the first time, this type of hetero-bimetallic precursors was used for the preparation of NiCo₂O₄ (nickel cobaltite) nanospinels by calcination method. The results clearly showed the effect of different precursors on the final nanoparticles. The actual yield for the preparation of the nanospinels from [Ni(en)₃][Co(edta)]₂ precursor was greater than the yield for [Co(en)₃]₂[Ni(edta)]₃ precursor. The nanospinels were characterized using different techniques such as FT-IR, UV–Vis, zeta potential measurement, X-ray diffraction analysis (XRD), field-emission scanning electron microscopy (FE-SEM), and Brunauer–Emmett–Teller (BET) surface area measurement. Also, the catalytic activity of NiCo₂O₄ nanospinels was investigated for the oxidation of Rhodamine B to innocuous compounds at room temperature in water. The oxidation reaction was carried out in a batch reactor at ambient temperature and pressure with different reaction parameters such as reaction time, dye concentration, and catalyst loading. The cationic dye Rhodamine B ([C₂₈H₃₁N₂O₃]⁺Cl^–) was almost completely oxidized in the optimized reaction conditions. In addition, the catalysts could be recovered and reused successfully several times. - Highlights: • The first application of hetero-bimetallic precursors for the preparation of nanospinels. • The catalytic activity of the nanospinels for the oxidation of Rhodamine B. • The influence of the precursor on the catalytic efficiency.