Showing papers on "Iron oxide published in 2022"
TL;DR: In this article , a review of the preparation methods and characteristics of iron-manganese oxide nanomaterials over the past decade and provided some basic information for the improvement of preparation methods.
37 citations
TL;DR: In this article , a modified magnetic Fe 3 O 4 /Clinoptilolite was synthesized in the laboratory as a magnetic nanosorbent for the removal of tetracycline (TC) from aqueous solution.
36 citations
TL;DR: In this paper , several methods, such as co-precipitation, polyol, hydrothermal, microemulsion, and sol-gel methods, are reported to synthesize magnetite nanoparticles with controllable physical and chemical properties that suit the required application.
Abstract: A broad spectrum of nanomaterials has been investigated for multiple purposes in recent years. Some of these studied materials are magnetics nanoparticles (MNPs). Iron oxide nanoparticles (IONPs) and superparamagnetic iron oxide nanoparticles (SPIONs) are MNPs that have received extensive attention because of their physicochemical and magnetic properties and their ease of combination with organic or inorganic compounds. Furthermore, the arresting of these MNPs into a cross-linked matrix known as hydrogel has attracted significant interest in the biomedical field. Commonly, MNPs act as a reinforcing material for the polymer matrix. In the present review, several methods, such as co-precipitation, polyol, hydrothermal, microemulsion, and sol-gel methods, are reported to synthesize magnetite nanoparticles with controllable physical and chemical properties that suit the required application. Due to the potential of magnetite-based nanocomposites, specifically in hydrogels, processing methods, including physical blending, in situ precipitation, and grafting methods, are introduced. Moreover, the most common characterization techniques employed to study MNPs and magnetic gel are discussed.
34 citations
TL;DR: In this paper , the role of iron oxide nanoparticles in wastewater treatment is discussed, since the separation process is simple via an external magnetic field and high surface area and high adsorption capacity.
Abstract: Nanotechnology provides the ability to manipulate materials at the nanoscale within desired properties and specific functions. This allows the material to be controlled and used in many application fields. The main area among these application domains is the environmental applications including the wastewater treatment. This area, precisely, can be divided into: treatment and remediation, sensing and detection and pollution control. Iron oxide nanoparticles have been studied in depth in many fields due to the advantages offered by this material over other materials. This wide use of iron oxide nanoparticles is more likely due to; low cost, separation by means of external magnetic fields, high surface area and high adsorption capacity. In addition, within the available standard techniques of separation it is not easy to treat crude oil in water. Thus, iron oxides nanoparticles can be used as coagulant in coagulation and flocculation procedure to remove oil droplets from oilfield produced water. Within this context and to highlight the importance of this topic in this research, the current study aims to contribute through a bibliographic review, within the available literature, the role of iron oxide nanoparticles in wastewater treatment. Based on the present study, it is possible to distinguish the different approaches and methods proposed to obtain iron oxide nanoparticles as well as their various applications, explicitly, the focus has been on wastewater treatment and supply technologies. Thus, the novelty of this study is utilizing iron oxides nanoparticles, since the separation process is simple via an external magnetic fields. Also, iron oxides nanoparticles possess high surface area, high pollutant adsorption capacity and have compatibility for functionalization by chemical groups and selecting organic compounds. Accordingly, this investigation is anticipated to contribute to the production bibliography about this theme and clarify the use of materials in nanoscale for wastewater treatments.
34 citations
TL;DR: In this article , a review of the potential use of nanoscale zero-valent iron (nZVI) and iron oxides (FeOx) for removal of toxic elements (TEs) from aqueous media is presented.
Abstract: Abstract Biochar (BC) has gained attention for removal of toxic elements (TEs) from aqueous media; however, pristine biochar often exhibits low adsorption capability. Thus, various modification strategies in BC have been developed to improve its removal capability against TEs. Nanoscale zero-valent iron (nZVI) and iron oxides (FeOx) have been used as sorbents for TE removal. However, these materials are prone to agglomeration and also expensive, which make their usage limited for large-scale applications. The nZVI technical demerits could be resolved by the development of BC-based composite sorbents through the loading of nZVI or FeOx onto BC surface. Nano zero-valent iron modified BC (nZVIBC), FeOx-modified BC (FeOxBC) have attracted attention for their capability in removing pollutants from the aqueous phases. Nonetheless, a potential use of nZVIBC and FeOxBC for TE removal from aqueous environments has not been well-realized or reviewed. As such, this article reviews: (i) the preparation and characterization of nZVIBC and FeOxBC; (ii) the capacity of nZVIBC and FeOxBC for TE retention in line with their physicochemical properties, and (iii) TE removal mechanisms by nZVIBC and FeOxBC. Adopting nZVI and FeOx in BC increases its sporptive capability of TEs due to surface modifications in morphology, functional groups, and elemental composition. The combined effects of BC and nZVI, FeOx or Fe salts on the sorption of TEs are complex because they are very specific to TEs. This review identified significant opportunities for research and technology advancement of nZVIBC and FeOxBC as novel and effective sorbents for the remediation of TEs contaminated water.
33 citations
TL;DR: In this article , the combustion behavior of single laser-ignited iron particles is investigated, and the results indicate that the near-peak temperature increases first fast and then slowly with an increase of oxygen concentration.
32 citations
TL;DR: In this paper, the combustion behavior of single laser-ignited iron particles is investigated by post-processing recorded high-speed camera images using an in-house developed particle tracking program.
31 citations
TL;DR: In this article, a green reagent, tannic acid (TNA), was used to assist the phase transformation from γ-Fe2O3 to the reduced form of Fe3O4.
27 citations
TL;DR: In this paper , the toxicity of ultrasmall Fe3O4 nanoparticles with diameters of 2.3, 4.2, and 9.3 nm was evaluated in mice by intravenous injection.
Abstract: Iron oxide nanoparticles have been approved by food and drug administration for clinical application as magnetic resonance imaging (MRI) and are considered to be a biocompatible material. Large iron oxide nanoparticles are usually used as transversal (T2) contrast agents to exhibit dark contrast in MRI. In contrast, ultrasmall iron oxide nanoparticles (USPIONs) (several nanometers) showed remarkable advantage in longitudinal (T1)-weighted MRI due to the brighten effect. The study of the toxicity mainly focuses on particles with size of tens to hundreds of nanometers, while little is known about the toxicity of USPIONs.We fabricated Fe3O4 nanoparticles with diameters of 2.3, 4.2, and 9.3 nm and evaluated their toxicity in mice by intravenous injection. The results indicate that ultrasmall iron oxide nanoparticles with small size (2.3 and 4.2 nm) were highly toxic and were lethal at a dosage of 100 mg/kg. In contrast, no obvious toxicity was observed for iron oxide nanoparticles with size of 9.3 nm. The toxicity of small nanoparticles (2.3 and 4.2 nm) could be reduced when the total dose was split into 4 doses with each interval for 5 min. To study the toxicology, we synthesized different-sized SiO2 and gold nanoparticles. No significant toxicity was observed for ultrasmall SiO2 and gold nanoparticles in the mice. Hence, the toxicity of the ultrasmall Fe3O4 nanoparticles should be attributed to both the iron element and size. In the in vitro experiments, all the ultrasmall nanoparticles (< 5 nm) of Fe3O4, SiO2, and gold induced the generation of the reactive oxygen species (ROS) efficiently, while no obvious ROS was observed in larger nanoparticles groups. However, the ·OH was only detected in Fe3O4 group instead of SiO2 and gold groups. After intravenous injection, significantly elevated ·OH level was observed in heart, serum, and multiple organs. Among these organs, heart showed highest ·OH level due to the high distribution of ultrasmall Fe3O4 nanoparticles, leading to the acute cardiac failure and death.Ultrasmall Fe3O4 nanoparticles (2.3 and 4.2 nm) showed high toxicity in vivo due to the distinctive capability in inducing the generation of ·OH in multiple organs, especially in heart. The toxicity was related to both the iron element and size. These findings provide novel insight into the toxicology of ultrasmall Fe3O4 nanoparticles, and also highlight the need of comprehensive evaluation for their clinic application.
23 citations
TL;DR: In this paper , the toxicity of ultrasmall Fe3O4 nanoparticles with diameters of 2.3, 4.2, and 9.3 nm was evaluated in mice by intravenous injection.
Abstract: Iron oxide nanoparticles have been approved by food and drug administration for clinical application as magnetic resonance imaging (MRI) and are considered to be a biocompatible material. Large iron oxide nanoparticles are usually used as transversal (T2) contrast agents to exhibit dark contrast in MRI. In contrast, ultrasmall iron oxide nanoparticles (USPIONs) (several nanometers) showed remarkable advantage in longitudinal (T1)-weighted MRI due to the brighten effect. The study of the toxicity mainly focuses on particles with size of tens to hundreds of nanometers, while little is known about the toxicity of USPIONs.We fabricated Fe3O4 nanoparticles with diameters of 2.3, 4.2, and 9.3 nm and evaluated their toxicity in mice by intravenous injection. The results indicate that ultrasmall iron oxide nanoparticles with small size (2.3 and 4.2 nm) were highly toxic and were lethal at a dosage of 100 mg/kg. In contrast, no obvious toxicity was observed for iron oxide nanoparticles with size of 9.3 nm. The toxicity of small nanoparticles (2.3 and 4.2 nm) could be reduced when the total dose was split into 4 doses with each interval for 5 min. To study the toxicology, we synthesized different-sized SiO2 and gold nanoparticles. No significant toxicity was observed for ultrasmall SiO2 and gold nanoparticles in the mice. Hence, the toxicity of the ultrasmall Fe3O4 nanoparticles should be attributed to both the iron element and size. In the in vitro experiments, all the ultrasmall nanoparticles (< 5 nm) of Fe3O4, SiO2, and gold induced the generation of the reactive oxygen species (ROS) efficiently, while no obvious ROS was observed in larger nanoparticles groups. However, the ·OH was only detected in Fe3O4 group instead of SiO2 and gold groups. After intravenous injection, significantly elevated ·OH level was observed in heart, serum, and multiple organs. Among these organs, heart showed highest ·OH level due to the high distribution of ultrasmall Fe3O4 nanoparticles, leading to the acute cardiac failure and death.Ultrasmall Fe3O4 nanoparticles (2.3 and 4.2 nm) showed high toxicity in vivo due to the distinctive capability in inducing the generation of ·OH in multiple organs, especially in heart. The toxicity was related to both the iron element and size. These findings provide novel insight into the toxicology of ultrasmall Fe3O4 nanoparticles, and also highlight the need of comprehensive evaluation for their clinic application.
22 citations
TL;DR: In this paper , an unconventional, eco-friendly technique utilizing a Hibiscus rosa sinensis flower (common name, China rose) extract as a reducer and stabilizer agent was successfully used for the synthesis of iron oxide nanoparticles.
Abstract: Iron oxide nanoparticles (α- Fe2O3) were synthesized using an unconventional, eco-friendly technique utilizing a Hibiscus rosa sinensis flower (common name, China rose) extract as a reducer and stabilizer agent. The microwave method was successfully used for the synthesis of iron oxide nanoparticles. Various volume ratios of iron chloride tetrahydrate to the extract were taken and heated by the microwave oven for different periods to optimize iron oxide nanoparticle production. The synthesized iron oxide nanoparticles were characterized using the ultraviolet-visible spectrometer (UV-Vis), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray diffraction (XRD). X-ray diffraction confirmed the formation of α- Fe2O3 nanoparticles (hematite). The average size of iron oxide nanoparticles was found to be 51 nm. The antibacterial activity of the synthesized iron nanoparticles was investigated against different bacteria such as Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, and Escherichia coli. The results showed that the synthesized iron nanoparticles exhibited an inhabitation effect on all studied bacteria.
TL;DR: In this paper, a green tea mediated combustion synthesis route is implemented to prepare iron oxide nanoparticles, and the prepared sample is annealed at 350 Â C. Chemical ferric nitrate and natural tannic acid extracted from green tea are used to prepare IR nanoparticles.
Abstract: A green tea mediated combustion synthesis route is implemented to prepare iron oxide nanoparticles. Chemical ferric nitrate and natural tannic acid extracted from green tea are used to prepare iron oxide nanoparticles, and the prepared sample is annealed at 350 °C. The crystal structure and phase of iron oxide nanoparticles have been analyzed using X-ray Diffraction (XRD). The crystallite size (D) and lattice constant (a) of the prepared and annealed samples are calculated. The mean crystallite size is found to be 23.4 nm for the prepared sample and 30.1 nm for the annealed sample. The morphological and compositional analysis are characterized through scanning electron microscopy (SEM) and EDX. The particle shape and size are recorded through tunneling electron microscopy (TEM) and the average grain size is 25 nm for as-prepared and 32 nm for annealed samples. The stability of colloidal systems of iron oxide nanoparticles has been assessed using the zeta potential. The as-prepared sample has a decent stability value of − 58.3 mV, whereas the annealed sample has an exceptional value of − 60.1 mV. The optical band gap of the samples is calculated from ultra-violet (UV–vis) spectra, and the energy band gap of the as-prepared samples is 2.24 eV, and the annealed sample is 2.78 eV. The gas sensing behavior of as-prepared and annealed iron oxide samples is analyzed for different aspects related to operating temperature, gas concentration, response-recovery time, and different gases.
TL;DR: The synthesis method of magnetic nanoparticles, their functionalization with bioinspired materials and (in particular) with polydopamine are discussed and some interesting applications of polydipamine-coated magnetic iron oxide nanoparticles will be pointed out.
Abstract: Magnetic iron oxide nanoparticles have been extensively investigated due to their applications in various fields such as biomedicine, sensing, and environmental remediation. However, they need to be coated with a suitable material in order to make them biocompatible and to add new functionalities on their surface. This review is intended to give a comprehensive overview of recent advantages and applications of iron oxide nanoparticles coated by polydopamine film. The synthesis method of magnetic nanoparticles, their functionalization with bioinspired materials and (in particular) with polydopamine are discussed. Finally, some interesting applications of polydopamine-coated magnetic iron oxide nanoparticles will be pointed out.
TL;DR: In this article , the speciation of Cd in iron (hydr)oxide-HA coprecipitates were studied by extraction, surface complexation model (SCM) calculation and characterization of the composites during the aging.
TL;DR: In this article , the performance of nano-sized amorphous iron-oxide particles deposited on montmorillonite clay (MMT) was compared to crystalline hematite and magnetite-coated MMT.
TL;DR: In this paper , two functional biochar (FM-RBC and FM-DBC) were used to remove Cd from water and effectively fix Cd in alkaline soil, thus, debasing the risk of Cd entry into the food chain.
Abstract: The development of remediation materials simultaneously suitable for Cd-contaminated water and soil is of great significance. In this study, the functional biochar (FM-RBC and FM-DBC) was prepared using branch and durian shell biochar (RBC and DBC, respectively) with iron-manganese oxide (Fe–Mn oxide) modification. The behaviors and mechanisms of Cd adsorption and stabilization in water and alkaline soil treated with FM-RBC and FM-DBC were explored. The results showed that the adsorption capacities of RBC and DBC for Cd had increased by 40–80 mg/g after the Fe–Mn oxide modification. The Cd adsorption was conformed to pseudo-second-order kinetic and the Langmuir isothermal models. After 35 days of soil cultivation, the maximum reduction rate of DTPA-Cd occurred in 3% FM-DBC treatments (37.73%), followed by in 3% FM-RBC (30.08%), all of which were significantly higher than that observed in 3% BC treatments (12.55–18.91%). Notably, the FM-RBC and FM-DBC treatments promoted the conversion of the exchangeable to the carbonate-bound and Fe/Mn oxyhydroxide fractions of Cd. The XRD, FTIR, and XPS analyses demonstrated that the loading amount of Fe–Mn oxide was positively correlated with the oxygen-containing functional group of biochar. CdO, Cd2Mn3O8 and CdCO3 were loaded on the FM-BC, indicating the existence of two main adsorption mechanisms: (1) the complexation with M-O (M: Fe, Mn) and acid oxygen-containing functional groups, (2) the precipitation with carbonate of Cd. In this work, we prepared two functional biochar that rapidly removes Cd from water and effectively fixes Cd in alkaline soil, thus, debasing the risk of Cd entry into the food chain.
TL;DR: In this paper, the impact of reduction post-treatment and phase segregation of cobalt iron oxide nanowires on their electrochemical oxygen evolution reaction (OER) activity is investigated.
Abstract: The impact of reduction post-treatment and phase segregation of cobalt iron oxide nanowires on their electrochemical oxygen evolution reaction (OER) activity is investigated. A series of cobalt iron oxide spinel nanowires are prepared via the nanocasting route using ordered mesoporous silica as a hard template. The replicated oxides are selectively reduced through a mild reduction that results in phase transformation as well as the formation of grain boundaries. The detailed structural analyses, including the 57Fe isotope-enriched Mössbauer study, validated the formation of iron oxide clusters supported by ordered mesoporous CoO nanowires after the reduction process. This affects the OER activity significantly, whereby the overpotential at 10 mA/cm2 decreases from 378 to 339 mV and the current density at 1.7 V vs RHE increases by twofold from 150 to 315 mA/cm2. In situ Raman microscopy revealed that the surfaces of reduced CoO were oxidized to cobalt with a higher oxidation state upon solvation in the KOH electrolyte. The implementation of external potential bias led to the formation of an oxyhydroxide intermediate and a disordered-spinel phase. The interactions of iron clusters with cobalt oxide at the phase boundaries were found to be beneficial to enhance the charge transfer of the cobalt oxide and boost the overall OER activity by reaching a Faradaic efficiency of up to 96%. All in all, the post-reduction and phase segregation of cobalt iron oxide play an important role as a precatalyst for the OER.
TL;DR: In this paper, the authors show that Fe0 is a much better catalyst for the reverse water-gas shift (rWGS) reaction than Fe3C and Fe4C. When the samples are aged in the reaction mixture during stability test, a new phase appeared: Fe5C2, resulting in a more active but less selective catalysts than Fe0 for the rWGS reaction.
TL;DR: In this paper , a new approach was proposed to model the aquathermolysis of Aschalcha's reservoir rock heavy oil in the presence and absence of iron oxide nanoparticles combined with hydrogen donor in water steam atmosphere at 200, 250, and 300 °C using different physical and chemical methods.
TL;DR: In this article , Raspberry stalks-derived biochar (BC), magnetic biochar-iron oxide composite (BC-Fe) and its derivative modified with urea, BC-Fe-U were synthesized, characterized and tested as(V) and Cr(VI) ion sorbents.
TL;DR: In this article , the mZVI surface was modified by sodium disilicate (Si-mZVIbm) using a mechanical ball-milling approach to enhance the sulfamethazine removal rate by 2.9-23.8 fold in relation to unmodified ZVI; this rate increased with the Si/Fe molar ratio.
Abstract: Microscale zero-valent iron (mZVI) is used as a catalyst for peroxide activation and, has attracted considerable attention for the degradation of organic contaminants. However, surface inherent oxide films impedes electron transfer in mZVI and decrease its activation efficiency. Herein, the mZVI surface was modified by sodium disilicate (Si-mZVIbm) using a mechanical ball-milling approach. The mechanochemically silicified mZVI enhanced the sulfamethazine removal rate by 2.9–23.8 fold in relation to unmodified ZVI; this rate increased with the Si/Fe molar ratio (0–8%). Reactive intermediates, including radicals and non-radicals, were efficiently generated via peroxydisulfate (PDS) activation over Si-mZVIbm both SO4•- and Fe(IV) contributed toward sulfamethazine removal. The excellent performance of PDS activation over Si-mZVIbm particles was attributed to the continuous generation of ferrous ions, which was due to the accelerated iron release and more effective Fe3+/Fe2+ cycles in the Si-mZVIbm/PDS system after silicification.
TL;DR: The physicochemical and pharmaceutical properties of the synthesised fluid and the therapeutic results, as seen in the in vivo experiments, provide insights into therapeutic hyperthermia using injected magnetite nanoparticles.
Abstract: In this study, we developed iron oxide nanoparticles stabilised with oleic acid/sodium oleate that could exert therapeutic effects for curing tumours via magnetic hyperthermia. A suspension of iron oxide nanoparticles was produced and characterised. The toxicity of the synthesised composition was examined in vivo and found to be negligible. Histological examination showed a low local irritant effect and no effect on the morphology of the internal organs. The efficiency of magnetic hyperthermia for the treatment of transplanted Walker 256 carcinoma was evaluated. The tumour was infiltrated with the synthesised particles and then treated with an alternating magnetic field. The survival rate was 85% in the studied therapy group of seven animals, while in the control group (without treatment), all animals died. The physicochemical and pharmaceutical properties of the synthesised fluid and the therapeutic results, as seen in the in vivo experiments, provide insights into therapeutic hyperthermia using injected magnetite nanoparticles.
TL;DR: The importance of different polymorphic forms of iron oxide nanoparticles attracted a lot of attentions in various applications due to their unique electrical, optical and magnetic properties as mentioned in this paper , and their excellent biocompatibility, high surface area, spherical shape, tunable nanoscale size and availability of synthesis route make them desirable in various biological and pharmaceutical applications.
Abstract: The importance of different polymorphic forms of iron oxide nanoparticles attracted a lot of attentions in various applications due to their unique electrical, optical and magnetic properties. Moreover, the excellent biocompatibility, high surface area, spherical shape, tunable nanoscale size and the availability of synthesis route make them desirable in various biological and pharmaceutical applications. To this aim, in this review, different synthesis methods of iron oxide nanoparticles were discussed, also the main characterization techniques used for elucidation of the iron oxide nanoparticles were reviewed. The exploitation of iron oxide nanoparticles-based systems as anticancer, antiviral, antimicrobial agents and its involvement in drug delivery system were reviewed in details. Additionally, the influence of nanoparticles size and the reagent type and conditions utilized in synthesis and their pharmaceutical applications was highlighted.
TL;DR: In this paper , a modified oxidation method of non-magnetic precursors following the green rust synthesis was used to obtain magnetic properties of large single domain iron oxide nanoparticles.
Abstract: This paper describes the preparation and obtained magnetic properties of large single domain iron oxide nanoparticles. Such ferrimagnetic particles are particularly interesting for diagnostic and therapeutic applications in medicine or (bio)technology. The particles were prepared by a modified oxidation method of non-magnetic precursors following the green rust synthesis and characterized regarding their structural and magnetic properties. For increasing preparation temperatures (5 to 85 °C), an increasing particle size in the range of 30 to 60 nm is observed. Magnetic measurements confirm a single domain ferrimagnetic behavior with a mean saturation magnetization of ca. 90 Am2/kg and a size-dependent coercivity in the range of 6 to 15 kA/m. The samples show a specific absorption rate (SAR) of up to 600 W/g, which is promising for magnetic hyperthermia application. For particle preparation temperatures above 45 °C, a non-magnetic impurity phase occurs besides the magnetic iron oxides that results in a reduced net saturation magnetization.
TL;DR: In this article, the effect of the Fe-content (10, 20, and 25% as Fe2O3) of three synthetic oxygen carriers supported on alumina was studied in a 1.5 kWth BCLG continuous unit.
TL;DR: In this paper , the surface colloidal properties of Fe oxides and their reactivity toward Humic Substances (HS) have been studied and compared with the state of the art regarding the adsorption/precipitation of HS onto iron mineral surfaces and their effects on binding metalloid and trace elements.
TL;DR: In this paper , the effect of Cd accumulation by iron and manganese oxides in wheat, and developed an efficient approach for amending Cd polluted weakly alkaline soils.
TL;DR: In this article , the formation of magnetic iron oxide monocrystalline nanoflowers in polyol solvents using N-methyldiethanolamine (NMDEA) as co-solvent has been shown to occur through a non-classical crystallization pathway.
TL;DR: In this paper , the authors used oyster shell powder as the promoter for forming and growing carbon nanotubes (CNTs) on the surface of the rGO surface, and then, NiFe layered double hydroxide (NiFeLDH) was deposited by electrochemical deposition to prepare the RGO-FeO-CNT-700-NiFe LDH electrodes, achieving an excellent capacitance of 411.9 F g −1 at a scan rate of 5 mV s −1 .
Abstract: • rGO-FeO-CNT-700 hierarchical structure were prepared by using oyster shell powder as the promoter for forming and grew CNTs on the rGO surface. • rGO-FeO-CNT-700-NiFeLDH-60 electrode shows an excellent capacitance of 411.9 F g -1 tested at 5 mV s -1 . • The good retention rate of 102.2% was attained after 5000 charge/discharged cycles. • The asymmetric supercapacitor delivers a high energy density. People's awareness regarding the environmental protection and energy crisis has greatly boost rapid development of advanced energy storage devices. In this regard, supercapacitors with long operation life and superior properties have considered as one of the powerful candidates for energy storage. Herein, electrodes with a 3D structure are fabricated by first mixing oyster shell powder with graphene oxide (GO) and iron sulfate solution and subsequently subjected to the hydrothermal reaction, in which GO is reduced to form reduced GO (rGO) and afterwards to fabricate rGO-FeOOH. Using dried rGO-FeOOH as the framework in the following chemical vapor deposition process, carbon nanotubes (CNTs) are successfully grew on the rGO surface. Then, NiFe layered double hydroxide (NiFeLDH) is deposited by electrochemical deposition to prepare the rGO-FeO-CNT-NiFeLDH electrodes. The rGO-FeO-CNT-700-NiFeLDH electrode performs an excellent capacitance of 411.9 F g −1 at a scan rate of 5 mV s −1 . The rGO-FeO-CNT-700-NiFeLDH-60//AC-NiO asymmetric supercapacitor performs an energy density of 41.4 W h kg −1 with a power density of 5600 W kg −1 . The capacitance increases up to 144.89% of its initial capacitance after operation for 3200 cycles and remains 102.2% capacitance retention after 5000 cycles demonstrating that the electrode with excellent property is applicable for energy storage devices.
TL;DR: In this paper, the formation of magnetic iron oxide monocrystalline nanoflowers in polyol solvents using N-methyldiethanolamine (NMDEA) as co-solvent has been shown to occur through a non-classical crystallization pathway.