Investigation on In Situ Carbon-Coated ZnFe2O4 as Advanced Anode Material for Li-Ion Batteries

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.

Facile synthesis of magnetic framework composite MgFe2O4@UiO-66(Zr) and its applications in the adsorption-photocatalytic degradation of tetracycline

Recently, metal-organic framework (MOF)-based hybrid composites have attracted significant attention in photocatalytic applications. In this work, MgFe₂O₄@UiO-66(Zr) (MFeO@UiO) composites with varying compositions were successfully synthesized via facile in situ assemblies. Depositing the UiO-66(Zr) framework onto ferrite nanoparticles yielded a composite structure having a lower bandgap energy (2.28-2.60 eV) than that of the parent UiO-66(Zr) (~3.8 eV). Moreover, the MFeO@UiO composite exhibited magnetic separation property and improved porosity. The removal experiment for tetracycline (TC) in aqueous media revealed that the MFeO@UiO composite exhibited a high total TC removal efficiency of ca. ~94% within 45-min preadsorption and 120-min visible-light illumination, which is higher than that of pristine ferrite and UiO-66(Zr). The enhanced photodegradation efficiency of MFeO@UiO is attributed to efficient interfacial charge transfer at the heterojunction and the synergistic effect between the semiconductors. Radical scavenging experiments revealed that photogenerated holes (h⁺) and hydroxyl radicals (·OH) were the major reactive species involved in TC photodegradation. Moreover, the prepared MFeO@UiO nanocomposite showed good recyclability and renewability, making it a potential material for wastewater treatments.

Facile Synthesis of ZnMn2O4@rGO Microspheres for Ultrasensitive Electrochemical Detection of Hydrogen Peroxide from Human Breast Cancer Cells

Mixed transition-metal oxides have witnessed increasing attention in catalysts and electrocatalysts. Herein, reduced graphene oxide-wrapped ZnMn₂O₄ microspheres (ZnMn₂O₄@rGO) were facilely synthesized through the solvothermal technique. The microstructure and morphology of ZnMn₂O₄@rGO microspheres were analyzed under Raman, X-ray photoelectron, X-ray diffraction, and energy-dispersive spectroscopies and scanning electron microscopy. The synthesized ZnMn₂O₄@rGO was employed as an excellent electrocatalyst for the reduction of hydrogen peroxide (H₂O₂). The ZnMn₂O₄@rGO-modified glassy carbon electrode (ZnMn₂O₄@rGO/GCE) exhibited a linear detection to H₂O₂ in a wide concentration range of 0.03-6000 μM with a detection limit of 0.012 μM. The biosensor was evaluated to determine H₂O₂ secreted by human breast cancer cells (MCF-7), indicating its promising applications in physiology and diagnosis.

Photocatalytic performance of visible active boron nitride supported ZnFe2O4 (ZnFe2O4/BN) nanocomposites for the removal of aqueous organic pollutants

ZnFe₂O₄/BN nanocomposites were synthesized using  solvothermal method. The microscopic images revealed uniform dispersion of ZnFe₂O₄ nanospheres on the surface of BN nanosheets. PL studies showed lower e⁻/h⁺ pair recombination.  ZnFe₂O₄/9.3% BN showed outstanding photocatalytic activity.

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

Single layer graphite, known as graphene, is an important material because of its unique two-dimensional structure, high conductivity, excellent electron mobility and high surface area. To explore the more prospective properties of graphene, graphene hybrids have been synthesised, where graphene has been integrated with other important nanoparticles (NPs). These graphene-NP hybrid structures are particularly interesting because after hybridisation they not only display the individual properties of graphene and the NPs, but also they exhibit further synergistic properties. Reduced graphene oxide (rGO), a graphene-like material, can be easily prepared by reduction of graphene oxide (GO) and therefore offers the possibility to fabricate a large variety of graphene-transition metal oxide (TMO) NP hybrids. These hybrid materials are promising alternatives to reduce the drawbacks of using only TMO NPs in various applications, such as anode materials in lithium ion batteries (LIBs), sensors, photocatalysts, removal of organic pollutants, etc. Recent studies have shown that a single graphene sheet (GS) has extraordinary electronic transport properties. One possible route to connecting those properties for application in electronics would be to prepare graphene-wrapped TMO NPs. In this critical review, we discuss the development of graphene-TMO hybrids with the detailed account of their synthesis. In addition, attention is given to the wide range of applications. This review covers the details of graphene-TMO hybrid materials and ends with a summary where an outlook on future perspectives to improve the properties of the hybrid materials in view of applications are outlined.

Critical Insight into the Relentless Progression Toward Graphene and Graphene-Containing Materials for Lithium-Ion Battery Anodes

Used as a bare active material or component in hybrids, graphene has been the subject of numerous studies in recent years. Indeed, from the first report that appeared in late July 2008, almost 1600 papers were published as of the end 2015 that investigated the properties of graphene as an anode material for lithium-ion batteries. Although an impressive amount of data has been collected, a real advance in the field still seems to be missing. In this framework, attention is focused on the most prominent research efforts in this field with the aim of identifying the causes of such relentless progression through an insightful and critical evaluation of the lithium-ion storage performances (i.e., 1^st cycle irreversible capacity, specific gravimetric and volumetric capacities, average delithiation voltage profile, rate capability and stability upon cycling). The "graphene fever" has certainly provided a number of fundamental studies unveiling the electrochemical properties of this "wonder" material. However, analysis of the published literature also highlights a loss of focus from the final application. Hype-driven claims, not fully appropriate metrics, and negligence of key parameters are probably some of the factors still hindering the application of graphene in commercial batteries.

Enhanced Photocatalytic Degradation of 17α-Ethinylestradiol Exhibited by Multifunctional ZnFe2 O4 -Ag/rGO Nanocomposite Under Visible Light

In this paper, ZnFe₂ O₄ , a visible light active photocatalyst, was comodified by graphene oxide (GO) and Ag nanoparticles (NPs) to form ZnFe₂ O₄ -Ag/rGO nanocomposite (NC) by facile one-pot hydrothermal method. Reduction of GO and formation of ZnFe₂ O₄ and Ag nanoparticles occurred simultaneously during hydrothermal reaction. The photocatalytic activity of the NC was investigated under visible light, for the degradation of 17α-ethinylestradiol (EE2), a nondye compound, which also is an emerging pollutant with endocrine-disrupting activity. The pseudo rate constant (k') of as-synthesized ZnFe₂ O₄ -Ag/rGO NC was higher by the factor of 14.6 and 5.6 times than the corresponding ZnFe₂ O₄ and ZnFe₂ O₄ /rGO respectively. The synergistic interactions between ZnFe₂ O₄ , Ag and rGO leading to decreased aggregation of the NPs, increased surface area, better absorption in visible region, effective electron-hole generation transfer. However, in the presence of humic acid (HA), the photosensitization effect was predominated by competitive interaction resulting in only 80% removal of EE2 within the same time. Moreover, the composite can easily be magnetically separated for reuse.

Ultrahigh cycling stability and rate capability of ZnFe2O4@graphene hybrid anode prepared through a facile syn-graphenization strategy

A ZnFe₂O₄@graphene hybrid anode with ultrahigh cycling stability and rate capability has been prepared through a facile syn-graphenization strategy.

An overview of AB2O4- and A2BO4-structured negative electrodes for advanced Li-ion batteries

Energy-storage devices are state-of-the-art devices with many potential technical and domestic applications.

Facile and large-scale fabrication of hierarchical ZnFe2O4/graphene hybrid films as advanced binder-free anodes for lithium-ion batteries

Hierarchical ZnFe₂O₄/graphene hybrid films are deposited on copper foils as a promising binder-free lithium-ion battery anode.

Synthesis of graphene-wrapped ZnMn2O4 hollow microspheres as high performance anode materials for lithium ion batteries

A facile method for the synthesis of graphene-wrapped ZnMn₂O₄ hollow microspheres which show excellent electrochemical performance.

CoMoO4 nanoparticles anchored on reduced graphene oxide nanocomposites as anodes for long-life lithium-ion batteries

A self-assembled CoMoO4 nanoparticles/reduced graphene oxide (CoMoO4NP/rGO), was prepared by a hydrothermal method to grow 3-5 nm sized CoMoO4 particles on reduced graphene oxide sheets and used as an anode material for lithium-ion batteries. The specific capacity of CoMoO4NP/rGO anode can reach up to 920 mAh g(-1) at a current rate of 74 mA g(-1) in the voltage range between 3.0 and 0.001 V, which is close to the theoretical capacity of CoMoO4 (980 mAh g(-1)). The fabricated half cells also show good rate capability and impressive cycling stability with 8.7% capacity loss after 600 cycles under a high current density of 740 mA g(-1). The superior electrochemical performance of the synthesized CoMoO4NP/rGO is attributed to the synergetic chemical coupling effects between the conductive graphene networks and the high lithium-ion storage capability of CoMoO4 nanoparticles.