Three-dimensional Fe2O3 nanocubes/nitrogen-doped graphene aerogels: nucleation mechanism and lithium storage properties

Nanoporous Plasmonic Microneedle Arrays Induced High-Efficiency Intracellular Delivery of Metabolism Regulating Protein

Patterned micro/nanostructure arrays have shown the potential to effectively regulate cellular behavior, and their unique microstructure may address the limitations of conventional pore materials, leading to novel phenomena. In this work, a large-area gold micro/nano-array substrate with an average hole of ≈32 nm is designed and extensively screened. Precisely engineered nanopores on the substrate can effectively improve photothermal conversion efficiency, and instant heat dissipation in the absence of laser irradiation. The mesoporous arrays are fabricated by hybrid lithography, offering advantages such as simple processing, high reproducibility, and immense commercial potential. Notably, its heating rate is as rapid as ≈45 K µs-1 at low power levels, with the cooling duration reduced to ≈50 µs after the laser irradiation. Metabolism regulatory proteins such as cytochrome C (CytoC) and β-galactosidase (β-gal) can be efficiently introduced into the U87 cell model without inducing phototoxicity or protein inactivation, maintaining catalytic activity to modulate the cellular metabolic state. This delivery platform based on transient nano-cyclones stimulating cell perturbations can be further expanded through modulated microstructures, such as delivering functional proteins or biomolecules for efficient intracellular regulation, cellular transfection, and in the future application as a potential high-throughput screening tool for clustered regularly interspaced short palindromic repeats (CAR-T) biopharmaceutical and clustered regularly interspaced short palindromic repeats (CRISPR) technologies.

The role of graphene aerogels in rechargeable batteries

Energy storage systems, particularly rechargeable batteries, play a crucial role in establishing a sustainable energy infrastructure. Today, researchers focus on improving battery energy density, cycling stability, and rate performance. This involves enhancing existing materials or creating new ones with advanced properties for cathodes and anodes to achieve peak battery performance. Graphene aerogels (GAs) possess extraordinary attributes, including a hierarchical porous and lightweight structure, high electrical conductivity, and robust mechanical stability. These qualities facilitate the uniform distribution of active sites within electrodes, mitigate volume changes during repeated cycling, and enhance overall conductivity. When integrated into batteries, GAs expedite electron/ion transport, offer exceptional structural stability, and deliver outstanding cycling performance. This review offers a comprehensive survey of the advancements in the preparation, functionalization, and modification of GAs in the context of battery research. It explores their application as electrodes and hosts for the dispersion of active material nanoparticles, resulting in the creation of hybrid electrodes for a wide range of rechargeable batteries including lithium-ion batteries (LIBs), Li-metal-air batteries, sodium-ion batteries (SIBs), zinc-ion batteries (AZIBs) and zinc-air batteries (ZABs), aluminum-ion batteries (AIBs) and aluminum-air batteries and other.

Chemical State of Potassium on the Surface of Iron Oxides: Effects of Potassium Precursor Concentration and Calcination Temperature

Potassium is used extensively as a promoter with iron catalysts in Fisher-Tropsch synthesis, water-gas shift reactions, steam reforming, and alcohol synthesis. In this paper, the identification of potassium chemical states on the surface of iron catalysts is studied to improve our understanding of the catalytic system. Herein, potassium-doped iron oxide (α-Fe₂O₃) nanomaterials are synthesized under variable calcination temperatures (400-800 °C) using an incipient wetness impregnation method. The synthesis also varies the content of potassium nitrate deposited on superfine iron oxide with a diameter of 3 nm (Nanocat^®) to reach atomic ratios of 100 Fe:x K (x = 0-5). The structure, composition, and properties of the synthesized materials are investigated by X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier-transform infrared, Raman spectroscopy, inductively coupled plasma-atomic emission spectroscopy, and X-ray photoelectron spectroscopy, as well as transmission electron microscopy, with energy-dispersive X-ray spectroscopy and selected area electron diffraction. The hematite phase of iron oxide retains its structure up to 700 °C without forming any new mixed phase. For compositions as high as 100 Fe:5 K, potassium nitrate remains stable up to 400 °C, but at 500 °C, it starts to decompose into nitrites and, at only 800 °C, it completely decomposes to potassium oxide (K₂O) and a mixed phase, K₂Fe₂₂O₃₄. The doping of potassium nitrate on the surface of α-Fe₂O₃ provides a new material with potential applications in Fisher-Tropsch catalysis, photocatalysis, and photoelectrochemical processes.

Regulating Lithium Plating and Stripping by Using Vertically Aligned Graphene/CNT Channels Decorated with ZnO Particles

Lithium (Li) metal is regarded as the ultimate anode material for use in Li batteries due to its high theoretical capacity (3860 mA h g^-1 ). However, the Li dendrites that are generated during iterative Li plating/stripping cycles cause poor cycling stability and even present safety risks, and thus severely handicap the commercial utility of Li metal anodes. Herein, we describe a graphene and carbon nanotube (CNT)-based Li host material that features vertically aligned channels with attached ZnO particles (designated ZnO@G-CNT-C) and show that the material effectively regulates Li plating and stripping. ZnO@G-CNT-C is prepared from an aqueous suspension of Zn(OAc)₂ , CNTs, and graphene oxide by using ice to template channel growth. ZnO@G-CNT-C was found to be mechanically robust and capable of guiding Li deposition on the inner walls of the channels without the formation of Li dendrites. When used as an electrode, the material exhibits relatively low polarization for Li plating, fast Li-ion diffusion, and high Coulombic efficiency, even over hundreds of Li plating/stripping cycles. Moreover, full cells prepared with ZnO@G-CNT-C as Li host and LiFePO₄ as cathode exhibit outstanding performance in terms of specific capacity (155.9 mA h g^-1 at 0.5 C), rate performance (91.8 mA h g^-1 at 4 C), cycling stability (109.4 mA h g^-1 at 0.5 C after 800 cycles). The methodology described can be readily adapted to enable the use of carbon-based electrodes with well-defined channels in a wide range of contemporary applications that pertain to energy storage and delivery.

Progress in Iron Oxides Based Nanostructures for Applications in Energy Storage

The demand for green and efficient energy storage devices in daily life is constantly rising, which is caused by the global environment and energy problems. Lithium-ion batteries (LIBs), an important kind of energy storage devices, are attracting much attention. Graphite is used as LIBs anode, however, its theoretical capacity is low, so it is necessary to develop LIBs anode with higher capacity. Application strategies and research progresses of novel iron oxides and their composites as LIBs anode in recent years are summarized in this review. Herein we enumerate several typical synthesis methods to obtain a variety of iron oxides based nanostructures, such as gas phase deposition, co-precipitation, electrochemical method, etc. For characterization of the iron oxides based nanostructures, especially the in-situ X-ray diffraction and ⁵⁷Fe Mössbauer spectroscopy are elaborated. Furthermore, the electrochemical applications of iron oxides based nanostructures and their composites are discussed and summarized.

Graphic Abstract

Reduced Graphene Oxide Aerogel inside Melamine Sponge as an Electrocatalyst for the Oxygen Reduction Reaction

A graphene oxide aerogel (GOA) was formed inside a melamine sponge (MS) framework. After reduction with hydrazine at 60 °C, the electrical conductive nitrogen-enriched rGOA-MS composite material with a specific density of 20.1 mg/cm³ was used to fabricate an electrode, which proved to be a promising electrocatalyst for the oxygen reduction reaction. The rGOA-MS composite material was characterized by elemental analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. It was found that nitrogen in the material is presented by different types with the maximum concentration of pyrrole-like nitrogen. By using Raman scattering it was established that the rGOA component of the material is graphene-like carbon with an average size of the sp²-domains of 5.7 nm. This explains a quite high conductivity of the composite obtained.

The α-Fe2O3/graphite anode composites with enhanced electrochemical performance for lithium-ion batteries

The α-Fe₂O₃/graphite composites were prepared by a thermal decomposition method using the expanded graphite as the matrix. The α-Fe₂O₃ nanoparticles with the size of 15-30 nm were embedded into interlayers of graphite, forming a laminated porous nanostructure with a main pore distribution from 2 to 20 nm and the Brunauer-Emmett-Teller surface area of 33.54 m² g^-1. The porous structure constructed by the graphite sheets can alleviate the adverse effects caused by the huge volume change of the α-Fe₂O₃ grains during the charge/discharge process. The composite electrode exhibits a high reversible capacity of 1588 mAh g^-1 after 100 cycles at 100 mA g^-1, 702 mAh g^-1 at 5 A g^-1, 460 mAh g^-1 at 10 A g^-1 after 160 cycles, respectively, showing good cycle stability and outstanding rate capability at high current densities.

MOF-derived hollow SiOx nanoparticles wrapped in 3D porous nitrogen-doped graphene aerogel and their superior performance as the anode for lithium-ion batteries

A nanocomposite anode material consisting of metal-organic framework (MOF)-derived hollow SiOx nanoparticles wrapped in three dimensional (3D) nitrogen-doped graphene aerogel (N-GA) has been fabricated through a facile three-step approach, involving MOF-template inducting, self-assembly and nitrogen-doping, freeze-drying and thermal treatment process. The hollow SiOx nanoparticles with an average size of 100-160 nm are distributed on 3D N-GA. Such nanocomposites possess a 3D porous structure with a BET surface area as high as 426.3 m2 g-1. In this nanostructure, the N-GA's property of interconnected porous network enables it to provide pathways for rapid electron transfer and Li+ transport, while the MOF-derived hollow SiOx nanoparticles with void space can accommodate the volume change during a lithiation/delithiation process. As a result, high rate capability (675 mA h g-1 under 50 C) as well as long-life cycling stability (1233.2 mA h g-1 under 10 C, 86% capacity retention over 500 cycles) is achieved.

"One-for-All" strategy to design oxygen-deficient triple-shelled MnO2 and hollow Fe2O3 microcubes for high energy density asymmetric supercapacitors

Intrinsically poor conductivity, sluggish ion transfer kinetics, and limited specific area are the three main obstacles that confine the electrochemical performance of metal oxides in supercapacitors. Engineered hollow metal oxide nanostructures can effectively satisfy the increasing power demand of modern electronics. In this work, both triple-shelled MnO₂ and hollow Fe₂O₃ microcubes have been synthesized from a single MnCO₃ template. The oxygen vacancies are introduced in both the positive and negative electrodes through a facile method. The oxygen vacancies can not only improve the conductivity and facilitate ion diffusion but also increase the electrode/electrolyte interfaces and electrochemically active sites. Consequently, both the oxygen-deficient triple-shelled MnO₂ and hollow Fe₂O₃ exhibit larger capacitance and rate capability than the samples without oxygen vacancies. Moreover, due to the matchable specific capacitance and potential window between the positive and negative electrodes, the asymmetric supercapacitor exhibits high specific capacitance (240 F g^-1), excellent energy density of 133 W h kg^-1 at 1176 W kg^-1, excellent power density (23 529 W kg^-1 at 73 W h kg^-1), and high cycling stability (90.9% after 5000 cycles). This strategy is highly reproducible in oxide-based electrodes, which have the potential to meet the requirements of practical application.

Cycling-Induced Capacity Increase of Graphene Aerogel/ZnO Nanomembrane Composite Anode Fabricated by Atomic Layer Deposition

Zinc oxide (ZnO) nanomembranes/graphene aerogel (GAZ) composites were successfully fabricated via atomic layer deposition (ALD). The composition of GAZ composites can be controlled by changing the number of ALD cycles. Experimental results demonstrated that the anode made from GAZ composite with ZnO nanomembrane of 100 ALD cycles exhibited highest specific capacity and best rate performance. A capacity increase of more than 2 times during the first 500 cycles was observed, and a highest capacity of 1200 mAh g^-1 at current density of 1000 mA g^-1 was observed after 500 cycles. On the basis of detailed electrochemical investigations, we ascribe the remarkable cycling-induced capacity increase to the alloying process accompanied by the formation of a polymer layer resulting from kinetically activated electrolyte degradation at low voltage regions.

Fabricating 3D Macroscopic Graphene-Based Architectures with Outstanding Flexibility by the Novel Liquid Drop/Colloid Flocculation Approach for Energy Storage Applications

Inspired by "water ripples" in nature and the flocculation phenomenon in colloid chemistry, a novel liquid drop/colloid flocculation approach is developed to fabricate an extremely flexible and compressible 3D macroscopic graphene-based architecture (hydrogels or aerogels), via a new coagulation-induced self-assembly mechanism. This facile and universal technique can be achieved in a neutral, acidic, or basic coagulation bath, producing microsized hydrogels with various structures, such as mushroom, circle, disc shapes, etc. The method also allows us to introduce various guest materials in the graphene matrix using transition metal salts as the coagulating bath. A mushroom-shaped NiCo oxide/GS hybrid aerogel (diameter: 3 mm) is prepared as an example, with ultrathin NiCo oxide nanosheets in situ grown onto the surface of graphene. By employing as binder-free electrodes, these hybrid aerogels exhibit a specific capacitance of 858.3 F g^-1 at 2 A g^-1, as well as a good rate capability and cyclic stability. The asymmetric supercapacitor, assembling with the hybrid aerogels as cathode and graphene hydrogels as anode materials, could deliver an energy density of 21 Wh kg^-1 at power density of 4500 W kg^-1. The ease of synthesis and the feasibility of obtaining highly flexible aerogels with varied morphologies and compositions make this method a promising one for use in the field of biotechnology, electrochemistry, flexible electronics, and environment applications.

Facile synthesis of Co3O4 nanosheets from MOF nanoplates for high performance anodes of lithium-ion batteries

Co₃O₄ nanosheets are readily synthesized from a nanoplate MOF precursor and showed a remarkable performance as an anode material for lithium-ion batteries.

Selective hydrazine sensor fabrication with facile low-dimensional Fe2O3/CeO2 nanocubes

Here, the binary-doped metal oxides of Fe₂O₃/CeO₂ nanocubes were prepared using reliable hydrothermal process, which is applied to fabricate an efficient and selective hydrazine chemical sensor shows good analytical sensing performances as well as validated the sensor prove with the environmental and extracted real samples.

Porous Fe2O3 Nanoframeworks Encapsulated within Three-Dimensional Graphene as High-Performance Flexible Anode for Lithium-Ion Battery

Integrating nanoscale porous metal oxides into three-dimensional graphene (3DG) with encapsulated structure is a promising route but remains challenging to develop high-performance electrodes for lithium-ion battery. Herein, we design 3DG/metal organic framework composite by an excessive metal-ion-induced combination and spatially confined Ostwald ripening strategy, which can be transformed into 3DG/Fe₂O₃ aerogel with porous Fe₂O₃ nanoframeworks well encapsulated within graphene. The hierarchical structure offers highly interpenetrated porous conductive network and intimate contact between graphene and porous Fe₂O₃ as well as abundant stress buffer nanospace for effective charge transport and robust structural stability during electrochemical processes. The obtained free-standing 3DG/Fe₂O₃ aerogel was directly used as highly flexible anode upon mechanical pressing for lithium-ion battery and showed an ultrahigh capacity of 1129 mAh/g at 0.2 A/g after 130 cycles and outstanding cycling stability with a capacity retention of 98% after 1200 cycles at 5 A/g, which is the best results that have been reported so far. This study offers a promising route to greatly enhance the electrochemical properties of metal oxides and provides suggestive insights for developing high-performance electrode materials for electrochemical energy storage.

Highly Efficient High-Pressure Homogenization Approach for Scalable Production of High-Quality Graphene Sheets and Sandwich-Structured α-Fe2O3/Graphene Hybrids for High-Performance Lithium-Ion Batteries

A highly efficient and continuous high-pressure homogenization (HPH) approach is developed for scalable production of graphene sheets and sandwich-structured α-Fe₂O₃/graphene hybrids by liquid-phase exfoliation of stage-1 FeCl₃-based graphite intercalation compounds (GICs). The enlarged interlayer spacing of FeCl₃-GICs facilitates their efficient exfoliation to produce high-quality graphene sheets. Moreover, sandwich-structured α-Fe₂O₃/few-layer graphene (FLG) hybrids are readily fabricated by thermally annealing the FeCl₃ intercalated FLG sheets. As an anode material of Li-ion battery, α-Fe₂O₃/FLG hybrid shows a satisfactory long-term cycling performance with an excellent specific capacity of 1100.5 mA h g^-1 after 350 cycles at 200 mA g^-1. A high reversible capacity of 658.5 mA h g^-1 is achieved after 200 cycles at 1 A g^-1 and maintained without notable decay. The satisfactory cycling stability and the outstanding capability of α-Fe₂O₃/FLG hybrid are attributed to its unique sandwiched structure consisting of highly conducting FLG sheets and covalently anchored α-Fe₂O₃ particles. Therefore, the highly efficient and scalable preparation of high-quality graphene sheets along with the excellent electrochemical properties of α-Fe₂O₃/FLG hybrids makes the HPH approach promising for producing high-performance graphene-based energy storage materials.

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.

Improving Surface Adsorption via Shape Control of Hematite α-Fe2O3 Nanoparticles for Sensitive Dopamine Sensors

α-Fe₂O₃ nanoparticles (NPs) with morphologies varying from shuttle to drum were synthesized through an anion-assisted and surfactant-free hydrothermal method by simply varying the ratios of ethanol and water in solvent. Control experiments show that the structural evolution can be attributed to a small-molecular-induced anisotropic growth mechanism in which the growth rate of α-Fe₂O₃ NPs along the a-, b-, or c-axis was well-controlled. The detailed structural analysis through the high-resolution transmission electron microscope (HRTEM) indicated that shuttle-like Fe₂O₃ NP surface was covered by high-density atomic steps, which endowed them with the enhanced adsorption and sensor ability toward dopamine (DA). The XPS characterizations indicated that the percentages of the O_C component follow the order of shuttle-like Fe₂O₃ (S-Fe₂O₃ for short) > pseudoshuttle-like Fe₂O₃ (Ps-Fe₂O₃ for short) > polyhedron-like Fe₂O₃ (Ph-Fe₂O₃ for short) > drum-like Fe₂O₃ (D-Fe₂O₃ for short). Benefits from these structural advantages, the S-Fe₂O₃ NPs-Nafion composite electrode exhibited remarkable electrochemical detection ability with a wide liner range from 0.2 μM to 0.107 mM and a low detection limit of 31.25 nM toward DA in the presence of interferents.

Preparation of Hollow Fe2O3 Nanorods and Nanospheres by Nanoscale Kirkendall Diffusion, and Their Electrochemical Properties for Use in Lithium-Ion Batteries

A novel process for the preparation of aggregate-free metal oxide nanopowders with spherical (0D) and non-spherical (1D) hollow nanostructures was introduced. Carbon nanofibers embedded with iron selenide (FeSe) nanopowders with various nanostructures are prepared via the selenization of electrospun nanofibers. Ostwald ripening occurs during the selenization process, resulting in the formation of a FeSe-C composite nanofiber exhibiting a hierarchical structure. These nanofibers transform into aggregate-free hollow Fe₂O₃ powders via the complete oxidation of FeSe and combustion of carbon. Indeed, the zero- (0D) and one-dimensional (1D) FeSe nanocrystals transform into the hollow-structured Fe₂O₃ nanopowders via a nanoscale Kirkendall diffusion process, thus conserving their overall morphology. The discharge capacities for the 1000^th cycle of the hollow-structured Fe₂O₃ nanopowders obtained from the FeSe-C composite nanofibers prepared at selenization temperatures of 500, 800, and 1000 °C at a current density of 1 A g⁻¹ are 932, 767, and 544 mA h g⁻¹, respectively; and their capacity retentions from the second cycle are 88, 92, and 78%, respectively. The high structural stabilities of these hollow Fe₂O₃ nanopowders during repeated lithium insertion/desertion processes result in superior lithium-ion storage performances.

Confined SnO2 quantum-dot clusters in graphene sheets as high-performance anodes for lithium-ion batteries

Construction of metal oxide nanoparticles as anodes is of special interest for next-generation lithium-ion batteries. The main challenge lies in their rapid capacity fading caused by the structural degradation and instability of solid-electrolyte interphase (SEI) layer during charge/discharge process. Herein, we address these problems by constructing a novel-structured SnO2-based anode. The novel structure consists of mesoporous clusters of SnO2 quantum dots (SnO2 QDs), which are wrapped with reduced graphene oxide (RGO) sheets. The mesopores inside the clusters provide enough room for the expansion and contraction of SnO2 QDs during charge/discharge process while the integral structure of the clusters can be maintained. The wrapping RGO sheets act as electrolyte barrier and conductive reinforcement. When used as an anode, the resultant composite (MQDC-SnO2/RGO) shows an extremely high reversible capacity of 924 mAh g(-1) after 200 cycles at 100 mA g(-1), superior capacity retention (96%), and outstanding rate performance (505 mAh g(-1) after 1000 cycles at 1000 mA g(-1)). Importantly, the materials can be easily scaled up under mild conditions. Our findings pave a new way for the development of metal oxide towards enhanced lithium storage performance.

Seaweed-Derived Route to Fe2O3 Hollow Nanoparticles/N-Doped Graphene Aerogels with High Lithium Ion Storage Performance

We developed a nanoscale Kirkendall effect assisted method for simple and scalable synthesis of three-dimensional (3D) Fe2O3 hollow nanoparticles (NPs)/graphene aerogel through the use of waste seaweed biomass as new precursors. The Fe2O3 hollow nanoparticles with an average shell thickness of ∼6 nm are distributed on 3D graphene aerogel, and also act as spacers to make the separation of the neighboring graphene nanosheets. The graphene-Fe2O3 aerogels exhibit high rate capability (550 mA h g(-1) at 5 A g(-1)) and excellent cyclic stability (729 mA h g(-1) at 0.1 A g(-1) for 300 cycles), outperforming all of the reported Fe2O3/graphene hybrid electrodes, due to the hollow structure of the active Fe2O3 NPs and the unique structure of the 3D graphene aerogel framework. The present work represents an important step toward high-level control of high-performance 3D graphene-Fe-based NPs aerogels for maximizing lithium storage with new horizons for important fundamental and technological applications.

Unraveling the formation mechanism of graphitic nitrogen-doping in thermally treated graphene with ammonia

Nitrogen-doped graphene (N-graphene) has attractive properties that has been widely studied over the years. However, its possible formation process still remains unclear. Here, we propose a highly feasible formation mechanism of the graphitic-N doing in thermally treated graphene with ammonia by performing ab initio molecular dynamic simulations at experimental conditions. Results show that among the commonly native point defects in graphene, only the single vacancy 5–9 and divacancy 555–777 have the desirable electronic structures to trap N-containing groups and to mediate the subsequent dehydrogenation processes. The local structure of the defective graphene in combining with the thermodynamic and kinetic effect plays a crucial role in dominating the complex atomic rearrangement to form graphitic-N which heals the corresponding defect perfectly. The importance of the symmetry, the localized force field, the interaction of multiple trapped N-containing groups, as well as the catalytic effect of the temporarily formed bridge-N are emphasized, and the predicted doping configuration agrees well with the experimental observation. Hence, the revealed mechanism will be helpful for realizing the targeted synthesis of N-graphene with reduced defects and desired properties.

The effect of annealing on a 3D SnO2/graphene foam as an advanced lithium-ion battery anode

3D annealed SnO2/graphene sheet foams (ASGFs) are synthesized by in situ self-assembly of graphene sheets prepared by mild chemical reduction. L-ascorbyl acid is used to effectively reduce the SnO2 nanoparticles/graphene oxide colloidal solution and form the 3D conductive graphene networks. The annealing treatment contributes to the formation of the Sn-O-C bonds between the SnO2 nanoparticles and the reduced graphene sheets, which improves the electrochemical performance of the foams. The ASGF has features of typical aerogels: low density (about 19 mg cm(-3)), smooth surface and porous structure. The ASGF anodes exhibit good specific capacity, excellent cycling stability and superior rate capability. The first reversible specific capacity is as high as 984.2 mAh g(-1) at a specific current of 200 mA g(-1). Even at the high specific current of 1000 mA g(-1) after 150 cycles, the reversible specific capacity of ASGF is still as high as 533.7 mAh g(-1), about twice as much as that of SGF (297.6 mAh g(-1)) after the same test. This synthesis method can be scaled up to prepare other metal oxides particles/ graphene sheet foams for high performance lithium-ion batteries, supercapacitors, and catalysts, etc.

Air-expansion induced hierarchically porous carbonaceous aerogels from biomass materials with superior lithium storage properties

We developed a novel air-expansion method for the preparation of porous carbonaceous aerogels with hierarchically macroporous, mesoporous and microporous structures from rice.

α-Fe2O3 nanopillar arrays fabricated by electron beam evaporation for the photoassisted degradation of dyes with H2O2

Vertically aligned α-Fe₂O₃ nanopillar arrays (NPAs) were fabricated by thermally oxidizing Fe NPAs on Si, quartz and F-doped SnO₂ (FTO) substrates prepared by glancing angle e-beam deposition (GLAD).

Mutagenic Effects of Iron Oxide Nanoparticles on Biological Cells

In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism's ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the OPEN ACCESS Int. J. Mol. Sci. 2015, 16 23483 transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells.

One-Pot Hydrothermal Synthesis of FeMoO₄ Nanocubes as an Anode Material for Lithium-Ion Batteries with Excellent Electrochemical Performance

Metal molybdates nanostructures hold great promise as high-performance electrode materials for next-generation lithium-ion batteries. In this work, the facial design and synthesis of monodisperse FeMoO4 nanocubes with the edge lengths of about 100 nm have been successfully prepared and present as a novel anode material for highly efficient and reversible lithium storage. Well-defined single-crystalline FeMoO4 with high uniformity are first obtained as nanosheets and then self-aggregated into nanocubes. The morphology of the product is largely controlled by the experimental parameters, such as the reaction temperature and time, the ratio of reactant, the solution viscosity, etc. The molybdate nanostructure would effectively promote the insertion of lithium ions and withstand volume variation upon prolonged charge/discharge cycling. As a result, the FeMoO4 nanocubes exhibit high reversible capacities of 926 mAh g(-1) after 80 cycles at a current density of 100 mA g(-1) and remarkable rate performance, which indicate that the FeMoO4 nanocubes are promising materials for high-power lithium-ion battery applications.

Self-Sensing, Ultralight, and Conductive 3D Graphene/Iron Oxide Aerogel Elastomer Deformable in a Magnetic Field

Three-dimensional (3D) graphene aerogels (GA) show promise for applications in supercapacitors, electrode materials, gas sensors, and oil absorption due to their high porosity, mechanical strength, and electrical conductivity. However, the control, actuation, and response properties of graphene aerogels have not been well studied. In this paper, we synthesized 3D graphene aerogels decorated with Fe3O4 nanoparticles (Fe3O4/GA) by self-assembly of graphene with simultaneous decoration by Fe3O4 nanoparticles using a modified hydrothermal reduction process. The aerogels exhibit up to 52% reversible magnetic field-induced strain and strain-dependent electrical resistance that can be used to monitor the degree of compression/stretching of the material. The density of Fe3O4/GA is only about 5.8 mg cm(-3), making it an ultralight magnetic elastomer with potential applications in self-sensing soft actuators, microsensors, microswitches, and environmental remediation.

Iron oxide/graphene composites as negative-electrode materials for lithium ion batteries – optimum particle size for stable performance

We synthesized Fe₂O₃/graphene composites by a hydrothermal method.