Photocatalytic degradation of methylene blue under visible light by cobalt ferrite nanoparticles/graphene quantum dots

• Vo Chau Ngoc Anh,
• Le Thi Thanh Nhi,
• Le Thi Kim Dung,
• Dang Thi Ngoc Hoa,
• Nguyen Truong Son,
• Nguyen Thi Thao Uyen,
• Nguyen Ngoc Uyen Thu,
• Le Van Thanh Son,
• Le Trung Hieu,
• Tran Ngoc Tuyen and
• Dinh Quang Khieu

Beilstein J. Nanotechnol. 2024, 15, 475–489, doi:10.3762/bjnano.15.43

• [4]. Several magnetic nanomaterials that can be recycled and reused have been developed for catalysis or adsorption [5]. Among them are ferrites with the general formula of MFe2O4 (M: Mn, Fe, Co, Ni, Cu, and Zn). They are important magnetic materials. Among the spinel ferrites, CoFe2O4 (CF) is one of

• (Japan). High-resolution transmission electron microscopy (HR-TEM) observation was performed with a JEM 1010. The intermediates in the MB degradation were determined by using an Agilent 1100 LC/MS-MS system with an electron spray ionization source combined with an ion trap. Synthesis of CoFe2O4, CoFe2O4

• cobalt ferrite. The products were denoted as CF0.5, CF0.67, CF1.0, and CF2.0, where the numeral is the initial Fe/Co molar ratio. CoFe2O4/GQDs were synthesized in a similar manner. A mixture of Co(NO3)2·6H2O (4.95 g), Fe(NO3)3·9H2O (3.44 g), and starch (C6H10O5)n (6.20 g) with a nCo/nFe/starch/nH2O molar

Enhancement of the piezoelectric coefficient in PVDF-TrFe/CoFe₂O₄ nanocomposites through DC magnetic poling

• Marco Fortunato,
• Alessio Tamburrano,
• Maria Paola Bracciale,
• Maria Laura Santarelli and
• Maria Sabrina Sarto

Beilstein J. Nanotechnol. 2021, 12, 1262–1270, doi:10.3762/bjnano.12.93

• consisting of CoFe2O4 nanoparticles dispersed in PVDF-TrFe with enhancement of the β phase alignment through an applied DC magnetic field. The magnetic poling was demonstrated to be particularly effective, leading to a piezoelectric coefficient d33 with values up to 39 pm/V. This type of poling does not need

• the use of a top electrode or of high magnetic fields (the maximum value of d33 was obtained at 50 mT, using a current of 0.4 A) making the PVDF-TrFE/CoFe2O4 nanocomposite suitable for the fabrication of highly efficient devices for energy harvesting and wearable sensors. Keywords: CoFe2O4; magnetic

• with zinc oxide nanostructures [1][3][5][6]. Recently, it was shown that the β phase content of PVDF can be improved introducing CoFe2O4 nanoparticles into the polymer and applying a DC magnetic field [25]. This effect has been ascribed to the strong tensile stress at the CoFe2O4/PVDF interfaces

The effect of magneto-crystalline anisotropy on the properties of hard and soft magnetic ferrite nanoparticles

• Hajar Jalili,
• Bagher Aslibeiki,
• Ali Ghotbi Varzaneh and
• Volodymyr A. Chernenko

Beilstein J. Nanotechnol. 2019, 10, 1348–1359, doi:10.3762/bjnano.10.133

• −xO4 NPs, with x = 0–1 in steps of 0.2, from soft magnetic (Fe3O4) to hard magnetic (CoFe2O4) ferrite, with a significant variation of the magnetic anisotropy. The phase purity and the formation of crystalline NPs with a spinel structure were confirmed through Rietveld refinement. The effect of Co

• observed that the heat efficiency of soft Fe3O4 is about 4 times larger than that of hard CoFe2O4 ferrite, which was attributed to the high coercive field of samples compared with the external field amplitude. Keywords: anisotropy; cobalt; ferrite; Henkel plots; hyperthermia therapy; nanoparticles

• importance to understand the physics of nanoparticle ensembles, which, in turn, is needed to develop technological applications of these systems. Among ferrites, CoFe2O4 NPs are of considerable interest because of their moderate saturation magnetization, good chemical stability and high intrinsic

Tailoring the magnetic properties of cobalt ferrite nanoparticles using the polyol process

• Malek Bibani,
• Romain Breitwieser,
• Alex Aubert,
• Vincent Loyau,
• Silvana Mercone,
• Souad Ammar and
• Fayna Mammeri

Beilstein J. Nanotechnol. 2019, 10, 1166–1176, doi:10.3762/bjnano.10.116

• knowledge, the best improvements made in this sense were those achieved by Zheng et al., who succeeded in designing self-assembled ferromagnetic CoFe2O4 nanopillars embedded in a ferroelectric BaTiO3 matrix [6], and by Acevedo et al. and Liu et al., who prepared CoFe2O4 and BaTiO3 nanoparticles (NPs

• magnetostrictive properties of the two most interesting samples, i.e., Co0.67Fe2.33O4, known to exhibit the highest magnetocrystalline anisotropy (Co-0.67-TriEG-6), and CoFe2O4, known to present the highest magnetostriction (Co-1-TetEG-6). XRD patterns of all the produced CoxFe3−xO4 powders. X-ray fluorescence

• experiments performed on two representative samples, Co-1-TetEG-6 and Co-0.67-TriEG-6. TEM images of CoFe2O4 NPs as a function of the polyol nature and the reaction time, and the corresponding diameter distributions and log-normal fits. Scale bar = 100 nm. TEM images of Co0.67Fe2.33O4 NPs as a function of the

Co-doped MnFe₂O₄ nanoparticles: magnetic anisotropy and interparticle interactions

• Bagher Aslibeiki,
• Parviz Kameli,
• Hadi Salamati,
• Giorgio Concas,
• Maria Salvador Fernandez,
• Alessandro Talone,
• Giuseppe Muscas and
• Davide Peddis

Beilstein J. Nanotechnol. 2019, 10, 856–865, doi:10.3762/bjnano.10.86

• of single phase MnFe2O4 (PDF Card No. 73-1964) and CoFe2O4 (PDF Card No. 22-1086) with no impurity phases detected in any sample. The crystallite size is estimated by Scherrer’s formula to be between 7 and 8 nm for all the samples (Table 1). The lattice constants, calculated by Equation 2, are almost

• equal for all the samples, which indicate that Co doping does not induce any significant structural variation. However, the obtained values (about 8.34 Å) are smaller than those reported for bulk CoFe2O4 (8.38 Å) and MnFe2O4 (8.51 Å) [24]. This can be justified by the effect of the cationic distribution

• remains constant for all Co-doped samples, suggesting that the samples have uniaxial anisotropy. While bulk CoFe2O4 has an ideal cubic magnetic anisotropy, the finite size effects on nanoparticles can suppress such behaviour showing only a small tendency to the cubic symmetry [2][12][19]. The DCD protocol

Cr(VI) remediation from aqueous environment through modified-TiO₂-mediated photocatalytic reduction

• Rashmi Acharya,
• Brundabana Naik and
• Kulamani Parida

Beilstein J. Nanotechnol. 2018, 9, 1448–1470, doi:10.3762/bjnano.9.137

• , leading to longer lifetime. As a result, NiFe2O4/TiO2 NRAs, ZnFe2O4/TiO2 NRAs and SrFe2O4/TiO2 NRAs exhibited enhanced photocatalytic activity as compared to bare TiO2 NRAs. On the other hand, the CB of CoFe2O4 is more positive than that of TiO2, while its VB is more negative than that of TiO2 [50][187

• ]. This made the CoFe2O4/TiO2 heterojunction nonconductive, resulting in inefficient separation of photoexcited charge carriers and hence poor photocatalytic activity was achieved. Metal-sulfide-modified TiO2 as visible-light-responsive photocatalysts for photoreduction of Cr(VI) Metal sulfides such as

Dynamic behavior of a nematic liquid crystal mixed with CoFe₂O₄ ferromagnetic nanoparticles in a magnetic field

• Emil Petrescu,
• Cristina Cirtoaje and
• Cristina Stan

Beilstein J. Nanotechnol. 2017, 8, 2467–2473, doi:10.3762/bjnano.8.246

• Emil Petrescu Cristina Cirtoaje Cristina Stan University Politehnica of Bucharest, Department of Physics, Splaiul Independenţei 313, 060042, Bucharest, Romania 10.3762/bjnano.8.246 Abstract The dynamic behavior of a mixture of 4-cyano-4′-pentylbiphenyl (5CB) with 1% CoFe2O4 nanoparticles was

• magnetic field to reorient the LC molecules and faster decrease the transition threshold. A mixture of 1% CoFe2O4 and the nematic 4-cyano-4′-pentylbiphenyl (5CB, Aldrich) was used in a 180 micrometer thick planar cell subjected to an external magnetic field. Due to their magnetic properties, the

• nanoparticles are agglomerating in long chains on which LC molecules are attached like leaves on a tree branch. Previous results [32] and microscopy images indicate that CoFe2O4 nanoparticles are gathering in long chains which align themselves parallel to the rubbing directions indicating a strong anchoring to

Methionine-mediated synthesis of magnetic nanoparticles and functionalization with gold quantum dots for theranostic applications

• Arūnas Jagminas,
• Agnė Mikalauskaitė,
• Vitalijus Karabanovas and
• Jūrate Vaičiūnienė

Beilstein J. Nanotechnol. 2017, 8, 1734–1741, doi:10.3762/bjnano.8.174

• spectroscopy, inductively coupled plasma mass spectroscopy (ICP-MS), and X-ray photoelectron spectroscopy (XPS) of as-formed CoFe2O4 NPs before and after decoration with gold QDs were applied. Keywords: functionalization; gold; magnetic nanoparticles; quantum dots; theranostics; Introduction In current

• application of Fe3O4@Met NPs for the adsorption of water pollutants. In this study, we report a novel synthesis protocol for superparamagnetic cobalt ferrite NPs capped with a biocompatible methionine shell (CoFe2O4@Met), which in turn is capable to reduce and attach the gold species. In this way, hybrid

• cobalt ferrite NPs with metionine molecules confers them strong non-fouling properties not allowing aggregate. The XRD pattern of these NPs (Figure 1c) implied the formation of pure, inverse spinel structure CoFe2O4, as all diffraction peaks at 2Θ positions: 18.29 (111), 30.08 (220), 35.44 (311), 43.06

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

• Arpita Jana,
• Elke Scheer and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2017, 8, 688–714, doi:10.3762/bjnano.8.74

Multiwalled carbon nanotube hybrids as MRI contrast agents

• Nikodem Kuźnik and
• Mateusz M. Tomczyk

Beilstein J. Nanotechnol. 2016, 7, 1086–1103, doi:10.3762/bjnano.7.102

• (SPIO/oMWCNT#Wu) [38], while Wang used the thermal annealing method of iron(II) acetate (SPIO/oMWCNT#Wang) [43]. Solvothermal co-precipitation of CoCl2 and FeCl3, also by Wu, led to the non-covalent deposition of magnetic cobalt ferrite (CoFe2O4/oMWCNT#Wu) [39]. It was found that a low temperature (180

• the dispersion stability of PM-b-PEG/SPIO@oMWCNT#Liu in phosphate-buffered saline (PSB) and in water, thus proving that the presence of the amphiphilic polymer PMETAC-b-PEGMA prevents sedimentation [33]. CoFe2O4/oMWCNT#Wu formed a stable aqueous dispersion for 2 weeks [39]. Maciejewska reported the

• therefore increasing the resulting relaxivity [36]. On the other hand, superparamagnetic nanoparticles, both in the most common SPIO and in others (e.g., CoFe2O4, CdTe quantum dots), anchored on the nanotube net require an extension of the SBM theory [13][14]. Moreover, the hypothesis of CNT as a conducting

Hemolysin coregulated protein 1 as a molecular gluing unit for the assembly of nanoparticle hybrid structures

• Tuan Anh Pham,
• Andreas Schreiber,
• Elena V. Sturm (née Rosseeva),
• Stefan Schiller and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2016, 7, 351–363, doi:10.3762/bjnano.7.32

• gluing unit for the assembly of often linear, hybrid structures of plasmonic gold (Au NP), magnetite (Fe3O4 NP), and cobalt ferrite nanoparticles (CoFe2O4 NP). Furthermore, the assembly of Au NPs into linear structures using Hcp1_cys3 is investigated by UV–vis spectroscopy, TEM and cryo-TEM. One key

• order to prove the catalytic performance of the gold hybrid structures, they are used as a catalyst in the reduction reaction of 4-nitrophenol showing similar catalytic activity as the pure Au NPs. To further extend the functionality of the Hcp1_cys3 gluing unit, Fe3O4 and CoFe2O4 NPs are aligned in a

• connection via gold–thiol binding. The Au NP network shows similar reactivity to the colloidal Au NPs as a catalyst in the reduction reaction of 4-nitrophenol to 4-aminophenol. To explore the broad application of our concept, Hcp1_cys3 is also applied to assemble Fe3O4 and CoFe2O4 NPs. The reaction is

Inorganic Janus particles for biomedical applications

• Isabel Schick,
• Steffen Lorenz,
• Dominik Gehrig,
• Stefan Tenzer,
• Wiebke Storck,
• Karl Fischer,
• Dennis Strand,
• Frédéric Laquai and
• Wolfgang Tremel

Beilstein J. Nanotechnol. 2014, 5, 2346–2362, doi:10.3762/bjnano.5.244

• the formation of the heterodimers, cube shape or cloverleaf shape particles were obtained (Figure 12); the iron oxide phase was always Fe3O4, independent of the domain morphology. The wet chemical approach was utilized as well to control the formation of either Co@Fe2O3 or CoFe2O4 [59]. As displayed

• of Chemistry. Synthetic protocol of the synthesis of Co@Fe2O3 heterodimer and phase pure CoFe2O4 nanoparticles (top) and corresponding (HR-)TEM images of (a,b) heterodimer particles and (c,d) isotropic CoFe2O4 nanoparticles. Reproduced with permission from [59]. Copyright 2011 The Royal Society of

Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses

• Annalena Wolff,
• Walid Hetaba,
• Marco Wißbrock,
• Stefan Löffler,
• Nadine Mill,
• Katrin Eckstädt,
• Axel Dreyer,
• Inga Ennen,
• Norbert Sewald,
• Peter Schattschneider and
• Andreas Hütten

Beilstein J. Nanotechnol. 2014, 5, 210–218, doi:10.3762/bjnano.5.23

• -like, triangular or irregular shapes, and small stoichiometric CoFe2O4 spheres were obtained after 28 days. In addition incomplete non-stoichiometric discs were observed throughout the growth process. The different disc shapes observed in the TEM measurements are sketched in the graph located in the

• middle section of Figure 2. The stoichiometric iron-rich spheres (CoFe2O4) are not considered here, since they only form as a side product after 12 minutes due to the choice of the starting composition. The starting ratio of cobalt to iron was chosen to 1:2 to allow for a comparison to our previous work

• [20]. Since the discs are of a cobalt rich composition, the remaining iron precursor in the solution forms the side product (CoFe2O4). The particles at different stages of the growth process are displayed in Figure 2. EELS and TEM measurements of the nanoparticles at early stages of the growth process

Magnetic nanoparticles for biomedical NMR-based diagnostics

• Huilin Shao,
• Tae-Jong Yoon,
• Monty Liong,
• Ralph Weissleder and
• Hakho Lee

Beilstein J. Nanotechnol. 2010, 1, 142–154, doi:10.3762/bjnano.1.17

• highest magnetization and r2 value, on account of their electron spin configurations, followed by FeFe2O4, CoFe2O4, and NiFe2O4. More recently, it has been demonstrated that magnetization can be further enhanced via additional Zn2+ dopant control in MnFe2O4 nanoparticles [46]. In addition, nanoparticle

Review and outlook: from single nanoparticles to self-assembled monolayers and granular GMR sensors

• Alexander Weddemann,
• Inga Ennen,
• Anna Regtmeier,
• Camelia Albon,
• Annalena Wolff,
• Katrin Eckstädt,
• Nadine Mill,
• Michael K.-H. Peter,
• Jochen Mattay,
• Carolin Plattner,
• Norbert Sewald and
• Andreas Hütten

Beilstein J. Nanotechnol. 2010, 1, 75–93, doi:10.3762/bjnano.1.10

• left for 15 to 28 days to allow for crystal growth. The nanoparticles obtained can be divided into Co2FeO4 and CoFe2O4 particles, Figure 4(b,c), which consist of small phase separated crystallites, Figure 4(d). The majority of larger particles is hexagonally or truncated hexagonally shaped and