Small Nanospheres Research Articles

Versatile synthesis of cellulose film with excellent electrothermal/photothermal dual responsiveness by introducing MXene and small molecule self-assembled nanosphere

Plant-derived biomaterials have great application prospects in solving environmental pollution and sustainable resource utilization, but the insufficient mechanical strength and lack of functional responsiveness often limit their further development. Inspired by natural small molecules functionalization, a vacuum-assisted filtration nanofibrillated cellulose (NFC)-based film with excellent antibacterial properties, mechanical strength, and electrothermal/photothermal dual-responsiveness was fabricated. As a natural bioactive molecule, antibacterial cinnamaldehyde (CA) is grafted onto tannic acid (TA) rich in pyrogallols via a small molecule self-assembly strategy, and then co-assembled with zinc acetate (ZA) through ion crosslinking to synthesize the functional TACA@ZA nanospheres. After incorporating the MXene and TACA@ZA, an inorganic-organic 3D network system was established in the NFC matrix through dynamic intermolecular hydrogen bonding and strong ionic cross-linking. The mechanical strength and toughness of hybrid composites are remarkably improved by 83.6 % and 418.9 %, respectively. Due to the synergistic effects of MXene and TACA@ZA, the designed NFC-based film also shows significantly enhanced antibacterial activity, UV-blocking ability, as well as photothermal and electrothermal performance. This bioinspired small molecule functionalization strategy opens an innovative design concept for the fabrication of multirole NFC-based biomaterials, which has great application prospects in the commercial fields of multifunctional adhesives, electronic devices, UV shielding coatings, and antibacterial materials.

A cleaner lignin-induced 3D porous MXenes hybrid electrode with enlarged voltage and high capacitance retention

Conventional supercapacitors face narrow voltage and an inevitable reduction in capacitance retention during operation, significantly preventing its further commercial application. So, biomass-derived composite materials have attracted intensive attention, especially for pseudocapacitive supercapacitors. Herein, a high-end utilization strategy of lignin to induce a 3D porous layered MXenes/graphene oxide hybrid electrode (LGM2-80) and homologous gel electrolytes with low interface resistance for lignin-derived supercapacitors is demonstrated by a simple hydrothermal method. A more uniform distribution and smaller nanospheres ≈<10 nm of lignin prevent the restacking and increase the interlayer spacing of graphene oxide, also play an adhesive role between graphene oxide and MXene, guaranteeing the maximization of the pseudocapacitance effect between lignin and MXene. Consequently, the LGM2-80 electrode showed a wide operating potential (−0.7∼1.0 V), breaking through the bottleneck of MXene-derived devices with limited working voltage (typically≤0.6 V). Furthermore, the lignin-derived symmetric quasi-solid-state supercapacitor (LGM2-80//lignin gel//LGM2-80) possesses an excellent capacitance retention rate of 149 % at 5,000 cycles, which is far exceeding the current reported supercapacitors. This innovative use of lignin opens up new perspectives for ultra-voltage and ultra-high capacitance retention of advanced supercapacitors.

Effect of Cu2O nanosphere size on femtosecond laser reductive sintering/melting for Cu printing

In this study, the size effect of Cu2O nanospheres on femtosecond laser reductive sintering/melting properties for Cu printing is investigated. First, two types of monodispersed Cu2O nanospheres (average sizes of 110 and 250 nm) are prepared using the polyol method. The particle size is significantly affected by the amount of polyvinylpyrrolidone because of the capping of initially-precipitated nanospheres and their aggregations. Both the prepared inks containing nanospheres and reducing agents exhibit the same reaction temperature in thermogravimetry and differential thermal analyses. These results indicate that the size of the nanospheres does not affect the reaction temperature. The small Cu2O nanospheres are well-sintered, whereas the large nanospheres are easily melted by irradiation with femtosecond laser pulses. As both inks possess the same reaction temperature, their printing properties depend on their thermal conductivity. The low thermal conductivity of the large nanosphere ink owing to their small reduced surfaces against volume induces local heating and subsequent melting, and the high thermal conductivity of the small nanosphere ink owing to their large reduced surfaces against volume increases sintering area. The sintered patterns fabricated using the small nanospheres exhibited an electrical conductivity of ∼1.1 × 106 S/m, which is 1/50 of pure Cu. These strong size effects of the nanospheres on direct writing demonstrate that mixed sizes of the nanospheres can improve the electrical conductivity of the patterns because of their high density and sufficient thickness.

Nonstoichiometric Nanocubes with a Controllable Morphology and Persistent Luminescence for Autofluorescence-Free Biosensing.

Persistent luminescence nanoparticles (PLNPs) have shown special advantages in areas such as bioimaging, cancer therapy, stress sensing, and photo-biocatalysis. However, the lack of methods for controllable synthesis of PLNPs with uniform morphologies and strong persistent luminescence has seriously hindered the applications of PLNPs. Herein, we reported that modifying the electronic structures of zinc gallogermanate (ZGGO) PLNPs by nonstoichiometric reactions can produce highly uniform nanocubes with controllable size and persistent luminescence. By nonstoichiometric increase of the Ge/Ga ratio in ZGGO, the ZGGO PLNPs were transformed from a mixture of nanocubes and small nanospheres into highly symmetrical and uniform large nanocubes, accompanied by the enhancement of persistent luminescence intensity by about 3.7 times. Moreover, we found that ZGGO PLNPs were responsive to reactive oxygen species (ROS), that is, the persistent luminescence of ZGGO can be quenched by ROS. Autofluorescence-free serum ROS detection was achieved with the developed PLNPs. Further, a biosensing assay for glucose oxidase (GOx) was designed based on the responsiveness of ZGGO PLNPs to H2O2. This study may pave a new way for better control of PLNPs' size, morphology, and persistent luminescence, and it can further promote the applications of PLNPs in areas ranging from theranostics to solar energy utilization.

Morphology-controlled atmospheric pressure plasma synthesis of zinc oxide nanoparticles for piezoelectric sensors

Zinc oxide nanoparticles, especially those with a high aspect ratio (i. e., nanorods and nanowires), are of great interest for many applications as they are piezoelectric, photocatalytic and antimicrobial. In the present study, a plasma flight-thru synthesis method was developed that allows controlling the particle size and shape of the zinc oxide nanoparticles. In a direct current thermal plasma reactor operated at atmospheric pressure, zinc powder injected into the plasma jet was molten, vaporized and oxidized, which allowed growing zinc oxide nanoparticles. The particle spectrum ranged from small nanospheres to nanorods, nanowires and multipodic nanoparticles such as tetrapods. The influence of the oxygen rate and the plasma power (correlated to the discharge current) on the particle morphology was studied, and the feasibility of the nanowire-like particles as piezoelectric sensor material was investigated. Piezoelectric test sensors, equipped with the plasma-synthesized zinc oxide nanowires, successfully responded to mechanical stimulation after poling.

Electrosynthesis of binder-free polypyrrole/nano- Bi2O3-Bi2O2CO3 composite for supercapacitor anode

β-Bi2O3-Bi2O2CO3 dispersed polypyrrole (PPy/β-Bi2O3-Bi2O2CO3) composite is electrochemically deposited on stainless steel mesh (SSM) surface in an acetonitrile solution of pyrrole monomer and pre-synthesized β-Bi2O3-Bi2O2CO3 nanoparticles. The coating is characterized compared with those of the PPy homopolymer coating and β-Bi2O3-Bi2O2CO3 powder using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), XPS, XRD, TEM, and FESEM. Flower-shaped spherical nanoparticles containing β-Bi2O3-Bi2O2CO3 phases are encapsulated in the partially oxidized PPy clusters composed of small nanospheres, thus dispersed well in the composite. The PPy/β-Bi2O3-Bi2O2CO3 coating exhibits a more capacitive behaviour than the PPy coating due to the electro-generation of Bi5+ in the β-Bi2O3-Bi2O2CO3 phases during the synthesis of composite and the supercapacitor cycling. The coated electrode provides a higher pseudocapacitive contribution (67.4 %) thanks to the mixed metal oxide of β-Bi2O3-Bi2O2CO3 in addition to PPy, exhibited a specific capacitance of 360 F g−1 in 100 mM Li2SO4. Bi2O2CO3 with a layered structure contributes to enlarge of active surface area, conductivity, and catalytic performance. A solid-state asymmetric cell is fabricated with polyvinyl alcohol (PVA)/Li2SO4 using 10 mg cm−2 mass-loaded PPy/β-Bi2O3-Bi2O2CO3 composite- and polyvinyl chloride (PVC)/carbon- coated SSM electrodes. The device provides 64.2 Wh kg−1 specific energy and 350 W kg−1 specific power at 0.5 A g−1 with a coulombic efficiency of 90 % and high stability of about 97 % for 5000 cycles. The electrode has the potential to be used as a binder-free electrode in high-performance supercapacitors.

Hollow silica nanospheres synthesized by one-step etching method to construct optical coatings with controllable ultra-low refractive index

HypothesisIt is generally believed that silica nanospheres deposited on substrates by sol-gel method to form coatings with low refractive index, if hollow structures are introduced into silica nanospheres, the obtained coatings can easily have an ultra-low refractive index (<1.15). However, with the currently reported techniques, facile and large-scale preparation of hollow silica nanospheres (HSNs) with diameters suitable for transparent optical coatings in a one-step method is hard to realize. Therefore, it is crucial to propose a one-step strategy to prepare HSNs colloids, and also to achieve controllable morphologies. ExperimentalStöber silica nanospheres were used as initial nanospheres, and diameters of nanospheres were controlled by the concentration of ammonia. Nanospheres of different diameters were etched using different concentrations of HF, and the structural transformation of nanospheres before and after etching was recorded. Etched nanospheres were deposited into coatings, refractive index was measured and appropriate coatings were selected to design and prepare a double-layer coating with broadband antireflection performance. FindingsExperiments indicated that nanospheres of different sizes exhibited different structural transformations after being etched by HF, and smaller nanospheres were aggregated and larger ones were hollowed out. It was the first time that HSNs have been prepared by one-step etching method. The refractive index of etched nanospheres was 1.387–1.057. The double-layer broadband antireflective coating designed and prepared using coatings with refractive index of 1.057 and 1.339 as upper and bottom layers respectively had an average transmittance of 99.5% in the visible region and exhibited a good antifogging property and weather durability.

Green Synthesis of Size-Controllable Polyfurfuryl Alcohol Nanospheres as Novel Bio-adsorbents

Nanomaterials derived from biomass preparation exhibit potential applications in the field of environmental protection. However, the synthesis methods still have some problems, including being a time-consuming and complex process and causing secondary pollution. In this work, polyfurfuryl alcohol (PFA) nanospheres are synthesized via a green method that uses water as the solvent, sodium dodecyl sulfate as the stabilizer, and p-benzenesulfonic acid monohydrate as the acid catalyst. In addition, the filtrate remained capable of preparing uniform nanospheres in five subsequent runs. Moreover, the size of PFA nanospheres could be regulated from 40 to 800 nm. The small PFA nanospheres provide a large surface area, suggesting more adsorption sites. PFA nanospheres are used first as novel bio-adsorbents for cationic dye (methylene blue) removal because of their abundant oxygen-containing functional groups and negative potential. Synthesis parameters and adsorption conditions affecting cationic dye removal, sorption mechanisms, and kinetics were studied. Results suggest that the synergistic effect of electrostatic attraction, π–π interactions, and hydrogen bonding contributes to the maximum adsorption capacity as high as 343.3 mg/g. Furthermore, the PFA nanospheres exhibited good regenerative properties. This work paves the way for the green and sustainable preparation of biomass furfuryl alcohol nanospheres.

Spatial nonlocality effect on the surface plasmon propagation in plasmonic nanospheres waveguide

Spatial nonlocality affects the plasmonic characteristics of nanostructures. We used the quasi-static hydrodynamic Drude model to obtain the surface plasmon excitation energies in various metallic nanosphere structures. The surface scattering and radiation damping rates were phenomenologically incorporated into this model. We demonstrate that spatial nonlocality increases the surface plasmon frequencies and total plasmon damping rates in a single nanosphere. This effect was amplified for small nanospheres and higher multipole excitation. In addition, we find that spatial nonlocality reduces the interaction energy between two nanospheres. We extended this model to a linear periodic chain of nanospheres. Then we obtain the dispersion relation of surface plasmon excitation energies using Bloch’s theorem. We also show that spatial nonlocality decreases the group velocities and energy decay lengths of the propagating surface plasmon excitations. Finally, we demonstrated that the effect of spatial nonlocality is significant for very small nanospheres separated by short distances.

In-situ and ultrasensitive detection of mercury (II) ions (Hg2+) using the localized surface plasmon resonance (LSPR) nanosensor and the microfluidic chip

Mercury is one of the most dangerous heavy metals due to its extreme toxicity to both humans and the biosphere. In this work, an in-situ and ultrasensitive method for the detection of mercury (II) ions (Hg2+) using the dark-field microspectroscopy-based localized surface plasmon resonance (LSPR) nanosensor is demonstrated. In our homemade high-throughput microfluidic chip, the fixed nanorods and the free small gold nanospheres combine to form the core-satellite structures with the help of T- Hg2+-T chemical coordination. Such a process results in a spectral red shift due to plasmonic coupling, which allows us to reach a picomolar detection limit and a linear response range from 10 pM to 10 µM. In addition, our LSPR nanosensor has excellent selectivity and no interference for the detection of Hg2+, which was evaluated by monitoring responses to different heavy metal ions (Pb2+, Cd2+, Cr2+, Ni2+, and Cu2+) and their mixed samples. Our sensor platform's effectiveness offers a practical method for detecting traces of Hg2+ in real-life water samples.

Synthesis of Sb2S3 nanosphere layer by chemical bath deposition for the photocatalytic degradation of methylene blue dye.

An antimony tri-sulfide Sb2S3 nanosphere photocatalyst was effectively deposited utilizing sodium thiosulfate and antimony chloride as the starting precursors in a chemical bath deposition process. This approach is appropriate for the large-area depositions of Sb2S3 at low deposition temperatures without the sulfurization process since it is based on the hydrolytic decomposition of starting compounds in aqueous solution. X-ray diffraction patterns and Raman spectroscopy analysis revealed the formation of amorphous Sb2S3 layers. The scanning electron microscopy images revealed that the deposited Sb2S3 has integrated small nanospheres into sub-microspheres with a significant surface area, resulting in increased photocatalytic activity. The optical direct bandgap of the Sb2S3 layer was estimated to be about 2.53 eV, making amorphous Sb2S3 appropriate for the photodegradation of organic pollutants in the presence of solar light. The possibility of using the prepared Sb2S3 layer in the photodegradation of methylene blue aqueous solutions was investigated. The degradation of methylene blue dye was performed to evaluate the photocatalytic property of Sb2S3 under visible light. The amorphous Sb2S3 exhibited photocatalytic activity for the decolorization of methylene blue solution under visible light. The mechanism for the photocatalytic degradation of methylene blue has been proposed. Our results suggest that the amorphous Sb2S3 nanospheres are valuable material for addressing environmental remediation issues.

A large-nanosphere/small-nanosphere (cellulose/silver) antibacterial composite with prominent catalytic properties for the degradation of p-nitrophenol

A well-designed spherical-nanocellulose (SNC)/silver-nanoparticle (AgNP) composite (SNC-AgNP) with a novel structure, a conjugate of large nanospheres (SNC, mean particle size 41 ± 9.7 nm) and small nanospheres (AgNPs, mean particle size 12 ± 6.3 nm), was prepared by the reduction of silver nitrate on plant-derived cellulose. The large nanospheres not only acted as a reducing agent, but more importantly, as a unique nano-spherical surface support, resulting in good dispersion of the small nanospheres. Thanks to this novel structure, the SNC-AgNPs possessed high antibacterial activity against the model microbes E. coli and S. aureus, and excellent catalytic properties for the degradation of p-nitrophenol. Notably, the catalytic rate constant (kapp = 1.6024 ± 0.0265 min−1) and catalytic activity factor (k = 5287.8 ± 644 min−1 g−1) of the SNC-AgNPs surpassed those of all cellulose-based Ag catalysts and most non-cellulose-based Ag catalysts. Moreover, the preparation of the SNC-AgNPs was high efficient, due to the high surface hydroxyl density of the SNC contributed from the cellulose II crystal structure, nano-spherical morphology, and low polymerization degree. Additionally, the thermal stability of the SNC-AgNPs was higher than most cellulose/Ag composite.

Antimicrobial nano-assemblies of tryptocidine C, a tryptophan-rich cyclic decapeptide, from ethanolic solutions

Tryptocidine C (TpcC), a Trp-rich cyclodecapeptide is a minor constituent in the antibiotic tyrothricin complex from Brevibacillus parabrevis. TpcC possesses a high tendency to oligomerise in aqueous solutions and dried TpcC forms distinct self-assembled nanoparticles. High-resolution scanning electron microscopy revealed the influence of different ethanol:water solvent systems on TpcC self-assembly, with the TpcC, dried from a high concentration in 15% ethanol, primarily assembling into small nanospheres with 24.3 nm diameter and 0.05 polydispersity. TpcC at 16 μM, near its CMC, formed a variety of structures such as small nanospheres, large dense nanospheroids and facetted 3-D-crystals, as well as sheets and coarse carpet-like structures which depended on ethanol concentration. Drying 16 μM TpcC from 75% ethanol resulted in highly facetted 3-D crystals, as well as small nanospheres, while those in 10% ethanol preparation had less defined facets. Drying from 20 to 50% ethanol led to polymorphic architectures with a few defined nanospheroids and various small nanoparticles, imbedded in carpet- and sheet-like structures. These polymorphic surface morphologies correlated with maintenance of fluorescence properties and the surface-derived antibacterial activity against Staphylococcus aureus over time, while there was a significant change in fluorescence and loss in activity in the 10% and 75% preparations where 3-D crystals were observed. This indicated that TpcC oligomerisation in solutions with 20–50% ethanol leads to metastable structures with a high propensity for release of antimicrobial moieties, while those leading to crystallisation limit active moieties release. TpcC nano-assemblies can find application in antimicrobial coatings, surface disinfectants, food packaging and wound healing materials.

Preparation of Mn3O4 microspheres via glow discharge electrolysis plasma as a high-capacitance supercapacitor electrode material

Manganic manganous oxide (Mn3O4) microspheres were prepared at 550 V discharge voltage in 2 g L−1 NaNO3 solution by one-step method via cathode glow discharge electrolysis (CGDE) plasma technique for high-capacitance supercapacitor electrode materials, in which Mn foil and Pt needle point were served as anode and cathode, respectively. The structure, phase composition and morphology of as-prepared products were characterized by FT-IR, XRD, XPS, SEM, TEM and BET analysis. A mechanism for the fabrication of Mn3O4 microspheres was proposed. The electrochemical behaviors of the Mn3O4 microspheres were examined in 1.0 mol L−1 Na2SO4 electrolyte. The results showed that Mn3O4 microspheres are composed of small nanospheres with sizes of about 20 nm and large nanospheres with sizes of about 177 nm. Specific surface area of microspheres is 48.03 m2 g−1. The Mn3O4 microsphere as an electrode has an outstanding specific capacitance of 360 F g−1 at 0.5 A g−1 and a superior cycling property of 83.6 % capacity retention after 1000 cycles at 1 A g−1, evidencing the potential as an electrode material for supercapacitor.

Hierarchical hollow superstructure cobalt selenide bird nests for high-performance lithium storage

The inferior cycling performance caused by large volume variation is the main problem that restricts the application of cobalt selenides in lithium-ion batteries. Herein, we synthesize raspberry-like Co-ethylene glycol precursor. It is further selenized into the hierarchical hollow superstructure CoSe2/CoSe bird nests that are assembled by the hollow nanosphere units of CoSe2 and CoSe nanocrystalline. CoSe2/CoSe bird nests achieve excellent cycling performance, high reversible capacity and satisfactory rate capability (1361 mAh/g at 1 A/g after 1000 cycles, 579 mAh/g at 2 A/g after 2000 cycles, 315 mAh/g at 5 A/g after 1000 cycles). Electrochemical kinetics analyses and ex-situ material characterization reveal that the surface capacitive behavior controls the electrochemical reaction, and the composite has low reaction impedance, fast and stable Li+ diffusion, and superior structural stability. The superior lithium storage performance is attributed to the unique superstructure bird nest. Large specific surface area, abundant hierarchical pores and the opening mouth result in high electrochemical activity, which induces high reversible capacity. The small hollow nanosphere units, the sufficiently thick hierarchical porous superstructure shell and the large hollow interior bring about the strong synergistic effect to improve cycling performance. The intimately coupling of CoSe2/CoSe nanocrystalline and the hollow nanosphere units guarantees high conductivity. This work has greatly enriched the understanding of structure design of high-performance cobalt selenide anodes.

An exceptional and universal DNA walker amplified “one-to-many” CRISPR/Cas12a-mediated fluorescent biosensor for ultrasensitive detection of non-DNA biomarkers

Although the recently found CRISPR/Cas12a system is a promising choice to significantly enhance the analytical accuracy and the construction flexibility of fluorescent biosensors, the traditional “one-to-one” mediation type and the short of effective target transduction routes can lead to a difficulty in improving sensitivity and detecting non-DNA analytes, respectively. In response to these challenging problems, we present here an exceptional and universal DNA walker amplified “one-to-many” CRISPR/Cas12a-mediated fluorescent biosensor. For this design, a nicking endonuclease is selected as the energy supply to drive an efficient walking process on the surface of a small size magnetic nanosphere. With the release of abundant activators, many CRISPR/Cas12a systems will be activated and finally trans-cleave a large number of reporters to actualize signal amplification. To extend the sensing species, a strand displacement and an aptamer competition triggered target transduction strategies are conceptually proposed. After using a photonic crystal coated biochip to further amplify the fluorescence emission, the newly-raised assay method can be successfully employed to severally determine a liver injury associated biomarker (microRNA-122) and a broad-spectrum tumor biomarker (carcinoembryonic antigen) by just a simple smartphone assisted imaging in an ultrasensitive and highly-specific manner. Moreover, our approach is capable of precisely measuring these targets in clinical human plasmas and also offer useful diagnostic information for drug-induced liver injury and lung cancer, greatly boosting the practical application ability of CRISPR based biosensors.

Two-Colour Sum-Frequency Generation Spectroscopy Coupled to Plasmonics with the CLIO Free Electron Laser

Nonlinear plasmonics requires the use of high-intensity laser sources in the visible and near/mid-infrared spectral ranges to characterise the potential enhancement of the vibrational fingerprint of chemically functionalised nanostructured interfaces aimed at improving the molecular detection threshold in nanosensors. We used Two-Colour Sum-Frequency Generation (2C-SFG) nonlinear optical spectroscopy coupled to the European CLIO Free Electron Laser in order to highlight an energy transfer in organic and inorganic interfaces built on a silicon substrate. We evidence that a molecular pollutant, such as thiophenol molecules adsorbed on small gold metal nanospheres grafted on silicon, was detected at the monolayer scale in the 10 µm infrared spectral range, with increasing SFG intensity of three specific phenyl ring vibration modes reaching two magnitude orders from blue to green–yellow excitation wavelengths. This observation is related to a strong plasmonic coupling to the thiophenol molecules vibrations. The high level of gold nanospheres aggregation on the substrate allows us to dramatically increase the presence of hotspots, revealing collective plasmon modes based on strong local electric fields between the gold nanoparticles packed in close contact on the substrate. This configuration favors detection of Raman active vibration modes, for which 2C-SFG spectroscopy is particularly efficient in this unusual infrared spectral range.

Supramolecular‐mediated ball‐in‐ball porous carbon nanospheres for ultrafast energy storage

AbstractHierarchical porous carbons are the most viable electrode material for supercapacitors because of their balanced capacitive performance and chemical stability. Their pore connectivity plays a pivotal role in electrolyte transport, which is quantified by a new parameter, defined in this work as the longest possible pore separation (LPPS). Herein, we report hierarchical porous carbon nanospheres (HPC‐NS) with a unique ball‐in‐ball structure, which is achieved by the pyrolysis of a supramolecular complex of γ‐cyclodextrin (γ‐CD)/PEO‐PPO‐PEO (F127). This approach differs from the conventional soft‐templating method in that, apart from the assembly of the monomicelles that leads to the host nanospheres (approximately 300 nm), the γ‐CD‐containing monomicelles themselves are converted to small porous carbon nanospheres (&lt;10 nm), which results in an ultralow LPPS of 10 nm, representing the best‐known pore connectivity of the HPC family. The HPC‐NS delivers a high specific capacitance (405 F g−1 at 1 A g−1 and 71% capacitance retention at 200 A g−1), wide voltage window (up to 1.6 V), and simultaneously high energy and power densities (24.3 Wh kg−1 at a power density of 151 W kg−1 and 9 Wh kg−1 at 105 W kg−1) in aqueous electrolytes. This new strategy boosts the development of porous carbon electrodes for aqueous supercapacitors with simultaneously high power and energy densities. image

Controllable Synthesis and Electrochemical Research of Zn2TiO4 Spheres as New Anode Materials for Lithium Ion Batteries

AbstractZn2TiO4 spheres are fabricated via a simple hydrothermal strategy combined with subsequent heating treatment of 600, 700, and 800 °C, respectively. All the as‐synthesized Zn2TiO4 spheres are assembled by many small nanospheres with a particle size of 20–100 nm. The compactness of Zn2TiO4 spheres is continuously enhanced as the temperature rises from 600 to 800 °C. Additionally, compared with the Zn2TiO4 calcined at 700 and 800 °C samples, the Zn2TiO4 sintered at 600 °C sample exhibits the best electrochemical performance, and it can deliver the high discharge specific capacities of 405, 269, 223, 193, 173, and 166 mAh g–1 at current densities of 50, 100, 200, 300, 400, and 500 mA g–1, respectively. Simultaneously, it also displays the excellent cyclic performance with a high reversible charge (discharge) capacity of 245.8 (247.7) mAh g–1 after 300 cycles at the current density of 200 mA g–1. The results demonstrate that the as‐prepared ZnTiO4 spheres sintered at 600 °C will be expected to be a new anode material of lithium ion batteries.

Carbon Nanospheres with High Intra‐ and Inter‐Sphere Porosities for High‐Rate Energy‐Storage Applications

AbstractKinetic problems restrict the applications of carbon‐based materials in energy‐storage systems at high currents. Herein, small carbon nanospheres (5 and 20 nm in average diameter) featured with high intra‐sphere micro‐/meso‐porosity and inter‐sphere meso‐/macro‐porosity are demonstrated as high‐rate anode materials for lithium‐ion batteries (capacity retention: 42.3 % at 1 A g−1 relative to 0.05 A g−1), enabling rapid lithium‐ion diffusion with shortened diffusion lengths. Additionally, the rapid lithium‐ion response is also verified with their superior capacitance retention at high currents as electrode materials for electrical double layer capacitors (capacitance retention: 69.2 % at 100 A g−1 relative to 0.5 A g−1). Our results confirm the optimum energy‐storage performance of this class of nanocarbons with hierarchical micro‐/meso‐/macro‐porous structures.