SPION-Graphene Nanocomposites for Electrochemical Energy Storage and Conversion Devices (original) (raw)
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Nanomaterials, 2019
Superparamagnetic iron oxide nanoparticles (SPIONs) have shown great potential in biomedicine due to their high intrinsic magnetization behaviour. These are small particles of magnetite or maghemite, and when coated, their surface oxidation is prevented, their aggregation tendency is reduced, their dispersity is improved, and the stability and blood circulation time are increased, which are mandatory requirements in biomedical applications. In this work, SPIONs were synthesized in air through a reduction-precipitation method and coated with four different polymers (Polyethylene glycol(PEG) 1000/6000 and dextran T10/T70). All the synthesized samples were structurally and magnetically characterized by transmission electron microscopy, Fourier transform infra-red spectroscopy, X-ray powder diffraction, Mössbauer spectroscopy, and Superconducting Quantum Interference Device (SQUID) magnetometry. SPIONs centrifuged and dried in vacuum with an average diameter of at least 7.5 nm and a com...
Applied Organometallic Chemistry, 2020
For the development of forward osmosis (FO) technology, proficient membranes are required for separation with appropriate transport characteristics. Polymer nanocomposites have been showing a great flexibility for tailoring membrane substrate. A layer-by-layer (LbL) method of polyelectrolyte has unveiled the best option for fabricating the required separation layer. In this research work, the nanocomposite of polyvinyl alcohol (PVA) and montmorillonite clay (surface modified with 25-30 wt% methyl dihydroxyethyl hydrogenated tallow ammonium (TA) (MMt-TA)) was used for membrane substrate fabrication. Particle size was measured for ensuring the clay size in nanorange. The pore forming agent was also added to enhance the porosity of FO substrate. Chitosan (CH) (polycation) and polyacrylic acid (PAAc) (polyanion) were employed as polyelectrolyte for surface modification of prepared substrate with three layers of CH/PAAc by the LbL method. The prepared nanocomposite membrane was named as "(PVA/MMt-TA/LiCl) 3LbL". (PVA/MMt-TA/LiCl) as a substrate and (PVA/MMt-TA/LiCl) 3LbL as FO membrane were characterized by scanning electron microscopy (SEM) for morphology. Thermogravimetric (TGA) analysis was used to understand the thermal behaviour of substrate as well as FO membrane. Substrate membrane porosity was also checked. (PVA/MMt-TA/LiCl) 3LbL membrane was tested on two feed solution i.e. deionised water (DI) and synthetic wastewater. Due to the formation of the high hydrophilic substrate, membrane showed high water flux (37.65 l m À 2 h À 1 (LMH)) and polyelectrolyte active layer restrained draw solute diffusion from draw solution to feed solution. It showed remarkable separation (0.2813 g À 2 h À 1 (gMH)) in active layer facing draw solution (AL-DS) mode for DI water as feed and 2 M NaCl solution as draw solution. Similarly, for synthetic wastewater, the flux was 34.35 LMH. This LbL approach has revealed that it is possible to fabricate novel high flux FO membranes with high water permeability and low reverse salt diffusion.
Biomedical and Pharmacology Journal, 2021
Superparamagnetic iron oxide nanoparticles (SPION) are commonly prepared by co-precipitation, a convenient and high yield producing method. However, this method produces large particles and wide size distribution. Thus, this study aims to optimize and determine the processing condition during the direct co-precipitation synthesis of citrate stabilized SPION (SPION-C). Processing conditions were optimized to achieve the suitable hydrodynamic size and zeta potential; measured straight after preparation, at weeks 3, 10, and 30. Characterization of optimized SPION and SPION-C was done by Fourier transform infrared spectroscopy (FTIR), fluorescence spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The optimized processing condition (stirring speed of 9000 rpm, stabilizer concentration of 1.006 M, and a 90oC stabilizer adsorption temperature), resulted in suitable SPION-C with a hydrodynamic size of 25.58 ± 7 nm, and zeta potential value of -50.8 ± 3.9. Pa...
Carboxylic acid functionalized SPION
Biofilms formed by antibiotic resistant Staphylococcus aureus (S. aureus) continue to be a problem for medical devices. Antibiotic resistant bacteria (such as S. aureus) often complicate the treatment and healing of the patient, yet, medical devices are needed to heal such patients. Therefore, methods to treat these biofilms once formed on medical devices are badly needed. Due to their small size and magnetic properties, superparamagnetic iron oxide nanopar-ticles (SPION) may be one possible material to penetrate biofilms and kill or slow the growth of bacteria. In this study, SPION were functionalized with amine, carboxylate, and isocyanate functional groups to further improve their efficacy to disrupt the growth of S. aureus biofilms. Without the use of antibiotics, results showed that SPION functionalized with carboxylate groups (followed by isocyanate then amine functional groups then unfunctionalized SPION) significantly disrupted biofilms and retarded the growth of S. aureus compared to untreated biofilms (by over 35% after 24 hours).
Easy Synthesis and Characterization of Holmium-Doped SPIONs
Nanomaterials
The exceptional magnetic properties of superparamagnetic iron oxide nanoparticles (SPIONs) make them promising materials for biomedical applications like hyperthermia, drug targeting and imaging. Easy preparation of SPIONs with the controllable, well-defined properties is a key factor of their practical application. In this work, we report a simple synthesis of Ho-doped SPIONs by the co-precipitation route, with controlled size, shape and magnetic properties. To investigate the influence of the ions ratio on the nanoparticles' properties, multiple techniques were used. Powder X-ray diffraction (PXRD) confirmed the crystallographic structure, indicating formation of an Fe 3 O 4 core doped with holmium. In addition, transmission electron microscopy (TEM) confirmed the correlation of the crystallites' shape and size with the experimental conditions, pointing to critical holmium content around 5% for the preparation of uniformly shaped grains, while larger holmium content leads to uniaxial growth with a prism shape. Studies of the magnetic behaviour of nanoparticles show that magnetization varies with changes in the initial Ho 3+ ions percentage during precipitation, while below 5% of Ho in doped Fe 3 O 4 is relatively stable and sufficient for biomedicine applications. The characterization of prepared nanoparticles suggests that co-precipitation is a simple and efficient technique for the synthesis of superparamagnetic, Ho-doped SPIONs for hyperthermia application.
New Journal of Chemistry, 2017
A facile and efficient method is used to synthesize porous iron oxide coated with graphene as electrode materials for lithium-ion batteries and supercapacitors. Graphene encapsulation of porous Fe 2 O 3 and Fe 3 O 4 nanorods is directly carried out from FeOOH@GO colloids by taking advantage of an electrostatic self-assembly method, owing to the positively-charged surface of FeOOH and the negatively-charged surface of GO. The combination of graphene and porous iron oxide brings about multifunctional features of the electrode materials as follows: (1) enhanced electrical conductivity makes the electrodes the current collectors; (2) reinforced softness of the electrodes accommodates the large volume changes during charge-discharge cycles; (3) improved high specific surface area of the electrodes increases the accessibility of the active electrode materials to electrolyte; (4) the pores formed by graphene and iron oxide particles facilitate ion transportation; (5) iron oxide particles separate graphene and prevent their restacking or agglomeration, and vice versa, thus improving the immersion and splitting of electrolyte into and out of the electroactive material. Consequently, the porous iron oxide/graphene hybrid nanocomposites deliver a good performance in the electrochemical energy storage for lithium-ion batteries and supercapacitors.
Facile Synthesis of Metal Oxides Sulphides and Phosphides for Enhanced Energy Applications
2021
Access to a reliable, sustainable, eco-friendly, and cost-effective energy supply is being challenged by the global increase in population and rapid technological advancement. Sophisticated systems, machinery, and various devices being innovated require a steady energy supply for their operations and applicability. To have this reliable energy, much research is being conducted through various approaches across the world. In this work, a facile approach in investigating and tuning the materials' properties was employed to improve the energy properties of metal oxides. Nanostructured NiFe oxide and CoFe oxide were synthesized using a facile coprecipitation method. It was revealed that nanostructured materials have favorable structures which promote their electrochemical efficiency. The structural and electrochemical properties of oxides were studied. To further investigate their properties, they were sulfurized and phosphorized using a hydrothermal and thermal process, respectively. The sulfides and phosphides showed impressive property improvement as compared to their respective oxides. NiFeoxide showed impressive oxygen evolution reaction and hydrogen evolution reactions with 298 mV and 54 mV overpotentials, respectively. After sulfurization, their results were further improved, except NiFe-oxide nanocubes (NiFe-NCs), whose HER overpotential was increased from 54 to 177 mV; while the rest of the samples showed v improvement of OER and HER overpotentials; from 298 for NiFe-NCs to 241 mV for NiFeS-NCs in OER, 258 for NiFe-oxide nanoparticles (NiFe-NPs) to 216 mV for NiFeS-NPs in OER; and 187 for NiFe-NPs to 152 mV for NiFeS-NPs in HER. Likewise, the materials' specific capacitance increased from 69 to 605 F/g for sulfurized NiFe-NCs and 186 to 515 F/g for sulfurized NiFe-NPs. The energy density of materials increased from 2 to 20 Wh/kg for NiFe-NCs and NiFeS-NCs, and from 6 to 17 Wh/kg for NiFe-NPs and NiFeS-NPs respectively, at 1 A/g. CoFe oxide samples showed good electrocatalytic and storage behavior. Their overpotentials decreased from 113 for CoFe-NCs to 52 mV for CoFeS-NCs and from 161 for CoFe-NPs to 122 mV for CoFeS-NPs. Their specific capacitance was also increased: specific capacitance of CoFe-NCs increased from 123 to 484 F/g for CoFeS-NCs and 161 of CoFe-NPs to 244 F/g for CoFeS-NPs. The energy density of CoFe-NCs increased from 4 to 17 Wh/kg after sulfurization, whereas for CoFe-NPs; the energy density increased from 5 to 8 Wh/kg, at 1 A/g. Upon phosphorization, the overpotentials values of 300, 330, 340, and 360 mV for phosphorized NiFe-nanoparticles (NiFeP-NPs), phosphorized CoFe-nanocubes (CoFeP-NCs), phosphorized NiFe-nanocubes (NiFeP-NCs) and phosphorized CoFe-nanoparticles (CoFeP-NPs) respectively, were observed, with some deviations from their unphosphorized counterparts which showed 256, 300, 298, and 300 mV overpotentials, respectively. The overpotentials for HER seemed to decrease when compared to their unphosphorized counterparts; 135, 121, 118, and 84 mV were determined for NiFeP-NPs, NiFeP-NCs, CoFeP-NPs, and CoFeP-NCs as compared to their unphosphorized samples vi overpotentials of 187, 54, 161, and 113 mV respectively. Specific capacitances of phosphorized samples were significantly improved; for CoFe-NCs, it increased from 123 to 248 F/g, 161 to 464 F/g for CoFe-NPs, 69 to 424 F/g for NiFe-NCs, and 186 to 214 F/g for NiFe-NPs. At the same time, the energy densities increased after phosphorization as shown in the following order; from 4 Wh/kg for CoFe-NCs to 9 Wh/kg for CoFeP-NCs, from 5 Wh/kg for CoFe-NCs to 16 Wh/kg for CoFeP-NPs, from 2 Wh/kg for NiFe-NCs to 15 Wh/kg for NiFeP-NCs, and from 6 Wh/kg for NiFe-NPs to 7 Wh/kg for NiFeP-NPs. The results of this study suggest that facile sulfurization and phosphorization of nanostructured NiFe oxides and CoFe oxides could significantly improve their electrocatalytic and capacitive behavior. vii