Size‐controlled Cobalt Ferrite Nanocrystals: Magnetically separable Reusable Nanocatalysts for Selective Oxidation of Styrene

Abstract

Superparamagnetic cobalt ferrite (CFO) nanocrystals (NCs) with sizes ∼ 6 nm and ∼ 4 nm were synthesized using a facile solvothermal method using fatty acids, lauric acid and stearic acid, as the capping agents. The synthesized nanocrystals were well characterized by XRD, FT-IR, XPS, SEM and TEM. The formation mechanism was explored and it was shown that the fatty acid was actually chemisorbed as a carboxylate onto the surface of CFO NCs. The experimental results specify that the size and size distribution of the CFO NCs were highly dependent on the length of fatty acid hydrophobic chain. Corresponding changes of the magnetic properties were investigated by measuring magnetization as a function of field and temper-ature, which suggest that the CFO NCs were superparamagnetic in nature. The catalytic properties for the oxidation of styrene in organic medium were examined by using the synthesized CFO NCs with sizes ∼ 6 nm and ∼ 4 nm. The synthesized CFO NCs, well dispersible in organic media, were demonstrated to be highly catalytically active, reached 100% conversion of styrene in 12 h with ∼ 77% and ∼ 82% selectivity for styrene oxide respectively. The magnetic CFO nanocatalysts were easily separated and recovered from the reaction medium by an external magnet, and reused for several cycles without losing catalytic selectivity for styrene oxide.[a] V.

Tannin-bridged magnetic responsive multifunctional hydrogel for enhanced wound healing by mechanical stimulation-induced early vascularization

“…The peak located at 532.5 eV can be attributed to chemisorbed oxygen species. 36 The peak at 530.1 eV is attributable to lattice oxygen (i.e., Fe-O) in the CFO. However, the broad complex O 1s peak of the TA-CFO NPs could be deconvoluted into three peaks, which also contains peaks for lattice oxygen.…”

“…The peak located at 532.5 eV can be attributed to chemisorbed oxygen species. 36 The peak at 530.1 eV is attributable to lattice oxygen ( i.e. , Fe–O) in the CFO.…”

Evaluation of Photocatalytic Activity in Water Pollutants and Cytotoxic Response of α-Fe2O3 Nanoparticles

“…Particle size control is very important for the photocatalysis process. In the literature, it is reported that NPs of controlled size showed high catalytic activity such as Fe 3 O 4 , in addition to being an effective catalyst material for the degradation of organic pollutants . Fe 3 O 4 NPs have also been used as the solid support for the development of magnetically recoverable catalytic systems .…”

Effect of Transition Metals (Mn, Co, Ni, and Zn) in Size-Controlled Metal Ferrite Nanocrystals on the Electrocatalytic Oxygen Evolution Reaction

“…12−14 Inspired by the above facts, here we have synthesized metal ferrite (MFO), M 2+ Fe 2 O 4 (M 2+ = Mn, Co, Ni, and Zn) NCs with a controlled size of ∼4 nm by a facile solvothermal method using stearic acid as the stabilizing agent via a similar protocol published earlier from our group. 15 The OER electrocatalytic performance of the ∼4 nm MFO NCs, [MnFe 2 O 4 (MnFO), CoFe 2 O 4 (CoFO), NiFe 2 O 4 (NiFO), and ZnFe 2 O 4 (ZnFO)] was examined in a 1 M KOH aqueous electrolyte using carbon paper (CP) and nickel foam (NF) as substrates. The as-synthesized MnFO, CoFO, NiFO, and ZnFO NCs exhibited distinct OER activity in different substrates, e.g., CP and NF.…”