Figure - available from: Journal of Materials Science
This content is subject to copyright. Terms and conditions apply.
a Low-resolution TEM, b high-resolution TEM and c relative size distribution of MnFe2O4 NPs; d Low-resolution TEM, e high-resolution TEM and f relative size distribution of ZnFe2O4 NPs; g Low-resolution TEM, h high-resolution TEM and i relative size distribution of CoFe2O4 NPs. Column on the right is the relative size distribution histograms, and the curves are the corresponding Gaussian fits
Source publication
Binary metal stearates were prepared from a direct reaction between metals and stearic acid, which act as single source precursors. Highly monodisperse manganese, cobalt and zinc ferrite (MnFe2O4, CoFe2O4, ZnFe2O4) NPs were synthesized by a direct pyrolysis of the as-synthesized bimetallic stearates without using any additional solvents. With the a...
Similar publications
The complexity of chemical compounds in lithium‐ion batteries (LIBs) results in great difficulties in the extraction of multiple transition metals, which have similar physicochemical characteristics. Here, we propose a novel strategy for selective extraction of nickel, cobalt, and manganese from spent LiNixCoyMn1−x−yO2 (NCM) cathode through the reg...
Citations
... V. This was largely attributable to decreases in Fe 3+ and Zn 2+ to Fe and Zn and Li-Zn and Li2O, the mechanism of Li-ion intercalation in accordance with Equation (1)-(5) [38]. After subsequent cycles of scanning, the reduction peaks of carbon-coated ZnFe2O4 shift- In order investigate the electrochemical mechanism during charging and discharging, CV analysis was performed to characterize the sample's electrochemical characteristics. ...
... V. This was largely attributable to decreases in Fe 3+ and Zn 2+ to Fe and Zn and Li-Zn and Li 2 O, the mechanism of Li-ion intercalation in accordance with Equations (1)-(4) [38]. After subsequent cycles of scanning, the reduction peaks of carbon-coated ZnFe 2 O 4 shifted to 1.0 V, which is due to changes in the internal structure of carbon coated ZnFe 2 O 4 . ...
ZnFe2O4 as an anode that is believed to attractive. Due to its large theoretical capacity, this electrode is ideal for Lithium-ion batteries. However, the performance of ZnFe2O4 while charging and discharging is limited by its volume growth. In the present study, carbon-coated ZnFe2O4 is synthesized by the sol–gel method. Carbon is coated on the spherical surface of ZnFe2O4 by in situ coating. In situ carbon coating alleviates volume expansion during electrochemical performance and Lithium-ion mobility is accelerated, and electron transit is accelerated; thus, carbon-coated ZnFe2O4 show good electrochemical performance. After 50 cycles at a current density of 0.1 A·g−1, the battery had a discharge capacity of 1312 mAh·g−1 and a capacity of roughly 1220 mAh·g−1. The performance of carbon-coated ZnFe2O4 as an improved anode is electrochemically used for Li-ion energy storage applications.
Corrosion in carbon steel (CS) has been an existing issue and it calls attention to the need for improved corrosion protection. At present, superhydrophobic (SHB) coating technology has piqued the interest of researchers as alternative means of mitigating metal corrosion. Herein, a one-step solution deposition process was used to prepare an SHB coating based on nano-zinc oxide/epoxy (ZnO/EP) on CS and its corrosion resistance performance was analyzed by the means of electrochemical analysis and compared with that of the blank CS metal and the regular coatings (plain EP and regular ZnO/EP). Results implied the as-prepared SHB coating shows remarkable improvement in corrosion protection for the substrate. Notably, it exhibited higher in both impedance modulus (|Z|) and coating resistance (Rc) results approaching 1010 Ωcm2, than those of regular coatings by 3 orders of magnitude to that of plain EP (∼107 Ω cm2), and 1 order of magnitude to regular coating (∼109 Ω cm2), indicating its superior corrosion resistance performance. Besides that, the superior inhibitive effect of the SHB ZnO/EP (ZES) is also proven by the potentiodynamic polarization (PDP) results, in which the Icorr value is suppressed down to 2.08 × 10−11 A/cm2, thereby achieving an excellent corrosion rate result of 3.38 × 10−11 mm/year. The exceptional barrier protection is ascribed to the presence of a stabilized air interlayer captured within the coating/electrolyte interface thus effectively blocking the penetration of electrolyte into the coating. This facile yet effective one-step processed SHB coating offers an effective route to improve the corrosion resistance performance of the CS metal and thereafter expand its potential applications.
Synergistic self-healing materials and inorganic particles to create self-healing superhydrophobic surfaces for improving their robustness is a common technique, but the suitability between the two is rarely mentioned. In this work, we developed a multifunctional superhydrophobic coating with room-temperature stability, mechanical stability, self-healing, and NIR stimuli response, in which self-healing polyurethane (PU) serves as the interface reinforcement layer and poly(dopamine) (PDA)-coated flower-like ZnO composite particles serve as the hydrophobic layer. A series of temperature-dependent self-healing PU materials were designed and synthesized by regulating the ratio of hard and soft chain segments in PU, and the relationship between the healing temperature of PU and the hydrophobic stability of the composite coatings was investigated. Based on dynamic hydrogen and disulfide bonds, PUs displayed excellent self-healing performance. Thanks to the self-healing and interfacial strengthening effect of PU and the photothermal properties of PDA, the composite coating exhibits not only excellent mechanical stability but also rapid self-healing ability in response to NIR stimuli. Furthermore, the smart coating demonstrated superior self-cleaning and corrosion resistance. This work provides a reference for developing strong and stable water-repellent reversible superhydrophobic coatings with great potential and promising future.
In this work a binary photocatalyst of rGO and MnFe2O4 was prepared completely using one-pot hydrothermal simple method. In this way, in a reaction vessel, graphene oxide was reduced and at the same time, MnFe2O4 nanoparticles were formed on its surface. The obtained catalyst was characterized by N2 adsorption, FT-IR, XPS, HRTEM, XRD, FESEM and VSM physicochemical techniques. The rGO/MnFe2O4-50% exhibits high photocatalytic efficiency for reduction of nitroaromatic compounds given to corresponding amines at ambient temperature. In this study, the kinetic parameter (k) of the reduction reaction was investigated. The catalyst was especially excellent in conversion of 1, 4-dinitrobenzene (99% in 30 min), 4-bromonitrobenzene (100% in 60 min) and 4-chloronitrobenzene (100% in 70 min). In addition to the photocatalytic behavior of rGO/MnFe2O4-50%, the recyclability of MnFe2O4 was exploited and the catalyst was used for a number of times in the nitrobenzene photocatalytic test without observing a significant decreasing in efficiency.
Structural biomimicry is a fascinating concept to explore hierarchically organized nanomaterials for mechanical structures, catalysis, sensing, and energy storage applications. Here we report the fabrication of biomimetic mesoporous cobalt ferrite/carbon nanoflake materials with helical morphologies and evaluate their electrochemical properties as free‐standing lithium‐ion battery (LIB) anodes. Iridescent chiral nematic mesoporous chitosan films obtained from crab shells were combined with binary metallic ions to afford helical cobalt ferrite/chitosan membranes. The cobalt ferrite/chitosan composites were thermally converted to cobalt ferrite/carbon replicas with hybrid nanoflakes arranged in a twisted Bouligand‐type mesoporous network. The structure of the materials was probed by electron microscopy, powder X‐ray diffraction, and Raman spectroscopy. We directly used these freestanding cobalt ferrite/carbon films as binder‐ and additive‐free LIB anodes, where they showed a first discharge capacity of 862 mAh g⁻¹ (at 100 mA g⁻¹), which faded during subsequent charge‐discharge cycles. Our work demonstrates a new potential use of chiroptical chitosan membranes to develop energy storage materials, a process that may be extended to other metal‐oxide based components.
Hierarchical ZnFe2O4 yolk-shell spheres (YSs) assembled from primary nanosheets are synthesized via a simple one-step solvothermal method followed by a heat-treatment process. A polypyrrole (PPy) conductive network is formed in-situ on pristine ZnFe2O4 YSs via chemical oxidative polymerization to obtain ZnFe2O4@PPy YSs. Morphological and structural characterization confirms that the conductive PPy coating does not destroy the localized porous microenvironment of pristine ZnFe2O4 with rapid mass transport. The solvothermal reaction time-dependent structure evolution and formation mechanism of ZnFe2O4@PPy YSs have been elucidated. Furthermore, the electrochemical performance of the ZnFe2O4@PPy YSs is assessed and compared with that of pristine ZnFe2O4 YSs. The results reveal that ZnFe2O4@PPy YSs exhibit excellent rate capability and long-term cycling stability, achieving 541.7 mAh g⁻¹ at 5 A g⁻¹ after 1000 cycles. The improved electrochemical performances of ZnFe2O4@PPy YSs are attributed to not only the structural advantages of porous yolk-shell architecture, but also the conductivity enhancement and suppressed volume expansion induced by the PPy layer.
In lithium-ion batteries, ZnFe2O4 as an anode has attracted wide attention due to high theoretical capacity. However, volume expansion of ZnFe2O4 during charging and discharging limits its commercial application. ZnFe2O4 is synthesized by one-step solvothermal method and subsequent heat-treatment process. Polypyrrole (PPy) prepared by chemical oxidation polymerization is in-situ coated onto the surface of spherical ZnFe2O4 to form ZnFe2O4@PPy, and used to enhance electronic conductivity and electrochemical performance of ZnFe2O4. This core-shell structure alleviates effectively volume expansion during charging and discharging, and accelerates movement of lithium ions and electrons, thus ZnFe2O4@PPy possesses good electrochemical performance with the discharge capacities of 1182 mAh g⁻¹ at a current density of 200 mA g⁻¹ after 100 cycles and 906 mAh g⁻¹ at 2000 mA g⁻¹ after 500 cycles.
We demonstrate a facile method to prepare monodisperse CoO–CoFe2O4 core-shell nanoparticles and a NaCl-assisted thermal sintering route to the generation of monodisperse core-shell structure of CoO–CoFe2O4 nanoparticles embedded in carbon sheet. Owing to the unique core-shell nanostructure, CoO–Co2FeO4 carbon nanosheets show excellent electrochemical performance as the anode material in lithium ion batteries. The discharge capacity can still maintain 1127 mAh g⁻¹ thoughout 50 cycles at current density of 100 mA g⁻¹. This synthetic strategy is inexpensive, facile and easily for large-scale production. The developed CoO–CoFe2O4 core-shell carbon nanosheets can be considered as promising battery materials.
