Solid Nanospheres Research Articles

Enhanced refractive index sensitivity of localized surface plasmon resonance inflection points in single hollow gold nanospheres with inner cavity

Hollow gold nanoparticles have great potential for localized surface plasmon resonance (LSPR) sensing. In this study, we investigated the refractive index (RI) sensitivities of single hollow gold nanosphere (HAuNS) with thin Au shell and inner cavity and single solid gold nanosphere (AuNS) in media with different RIs. The HAuNS exhibited a remarkable improvement in the RI sensitivity than the AuNS of similar size. The increased RI sensitivity of HAuNSs was ascribed to plasmon coupling between the inner and outer surface of the Au nanoshell. We then investigated the homogeneous LSPR scattering inflection points (IFs) to better understand the RI sensitivity of single HAuNS. The LSPR IF at the long wavelength side exhibited a better RI sensitivity compared to the wavelength shift of its counterpart LSPR maximum peak. Furthermore, the single HAuNS showed a remarkable improvement in the RI sensitivity at the LSPR IFs when compared to the AuNS of similar size. Therefore, we provided a new insight into the effect of inner cavity of HAuNS on the RI sensitivity of homogeneous LSPR IFs for use in LSPR-based biosensors.

Electrocatalytic activity of calcined manganese ferrite solid nanospheres in the oxygen reduction reaction.

In this study, we synthesized MnFe2O4 solid nanospheres (MSN) calcined at different temperatures (200-500°C) and MSN-based materials mixed with carbon black, for their use as electrocatalysts in the oxygen reduction reaction (ORR) in alkaline medium (0.1M KOH). It was demonstrated that the calcination temperature of MSN material determined its chemical surface composition and microstructure and it had an important effect on the electrocatalytic properties for ORR, which in turn was reflected in the performance of MSN/CB-based electrocatalysts. The study revealed that the presence of Mn species plays a key role in the ORR activity. Among tested, MSN200/CB and MSN350/CB exhibited the best electrochemical performances together with outstanding stability.

Superior Peroxidase-Like Activity of Gold Nanorattles in Ultrasensitive H2 O2 Sensing and Antioxidant Screening.

Nanozymes are artificial enzyme systems which are easy to produce, highly stable and cost-effective in comparison to natural enzymes. Herein, we evaluated the peroxidase-like activity of gold nanorattles (Au NRTs) having a solid gold octahedron core and thin, porous cubic gold shell. We also prepared solid gold nanocubes and nanospheres of similar sizes and surface charge as that of Au NRTs and compared their activity with standard horse radish peroxidase (HRP). All the prepared nanostructures followed Michaelis-Menten kinetics as observed from their substrate concentration vs. initial reaction velocity plot using 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. The kinetic parameters and the catalytic efficiency for the peroxidase-like activity of the nanostructures and HRP were calculated, and it was observed that Au NRTs possess the best nanozymatic activity with lowest KM and highest catalytic efficiency (kcat /KM ). The better activity of Au NRTs compared with other nanostructures and HRP could be attributed to the hollow porous structure with a solid core where different surfaces are available for reaction. Au NRTs, being the best amongst the tested nanozymes were further used for the sensing of hydrogen peroxide (H2 O2 ) and were found to sense H2 O2 down to 0.5 μM. Further, two naturally occurring antioxidants, tannic acid and ascorbic acid showed inhibitory effect on the peroxidase-like activity of Au NRTs in a concentration dependent manner which can be further used for screening of antioxidants or for determining the antioxidant potential.

3D Carbiyne Nanospheres Boosting Excellent Lithium and Sodium Storage Performance.

Reasonable design of electrode materials with specific morphology and structure can efficiently improve the metal ions storage and transmission properties of metal ion batteries. Here the preparation of spirobifluorene-based three-dimensional carbiyne nanosphere (SBFCY-NS) that is composed of spirobifluorene (SBF) and alkyne bonds is reported. Benefiting from the rigid spatial structure of SBF, numerous precursors are coupled through the connection of acetylene bonds, extending to form solid nanospheres. Abundant storage spaces and convenient multi-directional transmission paths for metal ions are available inside the three-dimensional (3D) carbiyne structure. Thus, SBFCY-NS is applied as efficient anode for lithium-ion battery and sodium-ion battery. The good stability of SBFCY-NS-based electrode and its improved Coulombic efficiency can be attributed to the special morphology of nanospheres, which can easily form thin and stable solid electrolyte interface film on the surface. Those results further promote the preparation of spherical carbon-based materials with abundant pores that can be applied in the field of electrodes.

Directionally tailoring the macroscopic polarization of piezocatalysis for hollow zinc sulfide on dual-doped graphene

Inefficient mechanical energy capture and inadequate active sites of piezoelectric materials remain the principal impediment for more widespread application in environmental remediation. Herein, a strategy was proposed to substantially improve the piezocatalytic performance via hybridizing hollow wurtzite ZnS nanospheres (H-ZnS) onto flexible S,N-codoped graphene (SNG). The resulting piezoelectric composite (H-ZnS@SNG) exhibited faster electrical transport and more superior piezocatalytic properties for dye degradation (~100% in 10 min) under external strain (either ultrasonic or mechanical stirring), compared with bulk H-ZnS (~58.4%) and the piezoelectric composite coupled with solid wurtzite ZnS nanospheres (S-ZnS@SNG, ~89.9%). This improvement is ascribed to the strain-induced piezopolarization charges of H-ZnS@SNG, with the unique hollow structure of the H-ZnS nanosphere accelerating the electron transfer of heterogeneous graphene. H-ZnS@SNG had the optimum crystal phase and morphology of H-ZnS at the annealing treatment temperature of 700 ℃, leading to the highest piezocatalytic performance. Simulations of the wurtzite hollow ZnS piezocatalyst ties the enhanced performance to excellent flexibility, along with more catalytic active sites on both inner and outer surfaces, compared with solid ZnS. This study provides valuable insights into the mechanisms underlying the excellent purification efficiency by hollow structural piezocatalysts, which are expected to be useful in customizing the designs of such materials for practical implementation. • Hollow structural H-ZnS@SNG fabricated by in-situ growth of hollow ZnS on graphene. • H-ZnS@SNG gave 100% removal, relative to 58% by H-ZnS and 90% by S-ZnS@SNG. • Hollow H-ZnS nanosphere enhanced electron transfer of heterogeneous graphene. • Optimum crystal phase and morphology of H-ZnS at annealing temperature of 700 ℃. • Simulations show hollow ZnS has excellent flexibility and more active sites.

Preparation of tailored lignin nanospheres with specific size and tunable structure by self-assembly of lignin from corn straw

As an environmentally friendly materials, lignin nanoparticles, especially the lignin nanospheres with controlled size or morphology, have shown great potentials in many areas. However, the lignin nanosphere with tailored structure was rarely reported to be prepared from lignin in raw lignocellulose. In this study, a protocol to produce lignin nanoparticles with tailored size and morphology directly from corn stover was investigated. Lignin was extracted from raw biomass with tetrahydrofuran (THF) as solvent, and then dialyzed in water. The fractionated lignin showed high hydrophobicity and dissolvability in organic solvent and was the ideal precursor to prepare nano-sphere, and the chemical modification of lignin was omitted. The smooth surface, non-porous structured and regular shaped spheres were formed through dialysis, which suggested that the dialysis time, dialysis temperature and the initial dosage of lignin were the factors effecting the morphology of lignin-nanosphere. By adjusting the factors, the morphology of lignin nano-spheres were able to be tailored with specific size and tunable structure, such as hollow nanosphere with 458−615 nm particle size, and solid nanosphere sized in 250−350 nm, 350−450 nm, 450−600 nm, 600−700 nm, 600−800 nm, 700−955 nm respectively. Moreover, the lignin nano-spheres with tailored structure showed different UV-blocking ability and bacterial culture capacity, which provided a promising development of lignin-based nanomaterials with raw biomass as the feedstock.

Ultranarrow and Tunable Fano Resonance in Ag Nanoshells and a Simple Ag Nanomatryushka.

We study theoretically the Fano resonances (FRs) produced by the near-field coupling between the lowest-order (dipolar) sphere plasmon resonance and the dipolar cavity plasmon mode supported by an Ag nanoshell or the hybrid mode in a simple three-layered Ag nanomatryushka constructed by incorporating a solid Ag nanosphere into the center of Ag nanoshell. We find that the linewidth of dipolar cavity plasmon resonance or hybrid mode induced FR is as narrow as 6.8 nm (corresponding to a high Q-factor of ~160 and a long dephasing time of ~200 fs) due to the highly localized feature of the electric-fields. In addition, we attribute the formation mechanisms of typical asymmetrical Fano line profiles in the extinction spectra to the constructive (Fano peak) and the destructive interferences (Fano dip) arising from the symmetric and asymmetric charge distributions between the dipolar sphere and cavity plasmon or hybrid modes. Interestingly, by simply adjusting the structural parameters, the dielectric refractive index required for the strongest FR in the Ag nanomatryushka can be reduced to be as small as 1.4, which largely reduces the restriction on materials, and the positions of FR can also be easily tuned across a broad spectral range. The ultranarrow linewidth, highly tunability together with the huge enhancement of electric fields at the FR may find important applications in sensing, slow light, and plasmon rulers.

Nanotechnology Based Cosmeceuticals

Nanotechnology manifests the progression within stage of research and development, by increasing the efficacy of the merchandise through delivery of innovative solutions. to beat certain drawbacks associated with the traditional products, application of nanotechnology is escalating within the world of cosmeceuticals. In private care industry, cosmeceuticals are considered the fastest growing segment and thus the use has risen drastically over the years. Nanocosmeceuticals used for skin, hair, nail, and lip care, for conditions like wrinkles, photoaging, hyperpigmentation, dandruff, and hair damage, have inherit widespread use. Novel nanocarriers like nano emulsions, liposomes, microemulsions, niosomes, solid lipid nanoparticles, nanospheres and nanostructured lipid carrier have replaced the usage of conventional delivery system. These novel nanocarriers have advantages of controlled and sustained drug release, enhanced skin penetration, higher stability, high entrapment efficiency and site-specific targeting. However, nanotoxicological researches have indicated concern regarding the impact of increased use of nanoparticles in cosmeceuticals as there are possibilities of nanoparticles to penetrate through skin and cause health hazards. This review on nanotechnology utilized in cosmeceuticals highlights the various novel carriers used for the delivery of cosmeceuticals, marketed formulations, their positive and negative aspects, toxicity, and regulations of nanocosmeceuticals.

Hollow mesoporous polydopamine nanospheres: synthesis, biocompatibility and drug delivery

Various polydopamine (PDA) nanospheres were synthesized by utilizing triblock copolymer Pluronic F127 and 1,3,5-trimethylbenzene (TMB) as soft templates. Precise morphology control of polydopamine nanospheres was realized from solid polydopamine nanospheres to hollow polydopamine nanospheres, mesoporous polydopamine nanospheres and hollow mesoporous polydopamine nanospheres (H-MPDANSs) by adjusting the weight ratio of TMB to F127. The inner diameter of the prepared H-MPDANSs can be controlled in the range of 50–100 nm, and the outer diameter is about 180 nm. Furthermore, the thickness of hollow mesoporous spherical shell can be adjusted by changing the amount of dopamine (DA). The H-MPDANSs have good biocompatibility, excellent photothermal properties, high drug loading capacity, and outstanding sustainable drug release properties. In addition, both NIR laser irradiation and acid pH can facilitate the controlled release of doxorubicin (DOX) from H-MPDANSs@DOX.

Spatiotemporal Temperature and Pressure in Thermoplasmonic Gold Nanosphere-Water Systems.

We offer a detailed investigation of the photophysical properties of plasmonic solid and hollow gold nanospheres suspended in water by combining ultrafast transient absorption (TA) spectroscopy with molecular dynamics (MD) simulations. TA reveals that hollow gold nanospheres (HGNs) exhibit faster excited state relaxation and larger amplitude acoustic phonon modes than solid gold nanoparticles of the same outer diameter. MD simulation carried out on full scale nanoparticle-water models (over 10 million atoms) to simulate the temporal evolution (0-100 ps) of the thermally excited particles (1000 or 1250 K) provides atomic-scale resolution of the spatiotemporal temperature and pressure maps, as well as visualization of the lattice vibrational modes. For the 1000 K HGN, temperatures upward of 500 K in the vicinity of the shell surface were observed, along with pressures up to several hundred MPa in the inner cavity, revealing potential use as a photoinduced nanoreactor. Our approach of combining TA and MD provides a path to better understanding how thermal-structural properties (such as expansion and contraction) and thermal-optical properties (such as modulated dielectrics) manifest themselves as TA signatures. The detailed picture of heat transfer at interfaces should help guide nanoparticle design for a wide range of applications that rely on photothermal conversion, including photothermal coupling agents for nanoparticle-mediated photothermal therapy and photocatalysts for light-driven chemical reactions.

Manganese ferrite solid nanospheres solvothermally synthesized as catalyst for peroxymonosulfate activation to degrade and mineralize para-nitrophenol: Study of operational variables and catalyst reutilization

MnFe2O4 solid nanospheres (MSN) were synthesized by a solvothermal method. The sample was then used as catalyst to activate potassium peroxymonosulfate (PMS) for the generation of sulfate (SO4.–) and hydroxyl (HO.) radicals to degrade and mineralize para-nitrophenol (PNP) in water. The aim of this work was to study the influence of operational variables on the activity of the MSN catalyst to degrade and mineralize PNP, the PMS consumption kinetics, the leaching of metal ions, and the removal of nitrogen. Results showed that 100% of PNP (0.1 mM) was removed in MSN/PMS system by degradation within 7 h at a dosage of 4 mM of PMS, 0.5 g L−1 of MSN, 40 °C, and pH0 5.8. The reusability of the MSN catalyst was also studied, and a PNP degradation pathway was proposed. The PNP degradation followed a pseudo-first-order kinetic model and the activation energy obtained was 37.1 kJ/mol. Under the above standard reaction conditions, the catalyst showed a good performance after five catalytic runs, with a degradation efficiency that exceeded 98%, and removed around 70% of total organic carbon in each run. The excellent reusability and long-term stability was verified by the characterization of fresh and used catalysts. The sole degradation products were maleic and fumaric acids and nitrate and nitrite ions.

Modeling of the Conductive Heat Transfer between Two Touching Nanoparticles in Nanoparticle-Based Materials

Nanoparticle-based materials (NBMs), whose thermal insulating performance is dominated by the heat transfer between two neighboring nanoparticles, have attracted tremendous attention in recent decades due to their potential applications in thermal insulation. This work provides an insight into the conductive heat transfer between two touching solid or hollow nanospheres by solving the gray phonon Boltzmann transport equation (BTE). The influence of some factors, including particle size, contact ratio, and shell thickness on the temperature distribution and effective thermal conductivity of two touching particles, is examined. Based on the thermal constriction resistance theory and numerical results, a prediction model for the effective thermal conductivity of two touching solid nanospheres is then proposed and proved to have high accuracy with a relative error less than 3.0%. Finally, a brand new effective thermal conductivity model for two touching hollow nanospheres with the same form as that of two touching solid spheres and an acceptable prediction error of 6.5% is also proposed.

Formation of V6O11@Ni(OH)2/NiOOH hollow double-shell nanoflowers for the excellent cycle stability of supercapacitors.

The rational design of multi-shelled hollow structured electrode materials is of great importance and has met with fundamental challenges in recent years. Herein, we demonstrate a combination approach of self-templating and sacrificial templating method for synthesizing double-shelled hollow nanoflower-structured V6O11@Ni(OH)2/NiOOH. Firstly, highly uniform vanadium-glycerate (VG) solid nanospheres are controllably synthesized and employed as the template, then Ni(OH)2/NiOOH nanosheets grow vertically on it, following with VG solid nanospheres changing to the V6O11 hollow structure. By controlling the amount of Ni(OH)2/NiOOH nanosheets, the optimized V6O11@Ni(OH)2/NiOOH-6 (VN-6) delivers high performance for supercapacitors. Specifically, the specific capacitance of VN-6 is 1018.2 F g-1 at the current density of 1 A g-1 and the energy density is 24.3 W h kg-1 at the power density of 850 W kg-1. Impressively, an outstanding cycling stability of over 120% specific capacitance retention can be obtained after 5000 cycles in the three-electrode and two-electrode systems. The excellent performance can be ascribed to the compositional and structural advantages.

Exploring water in oil emulsions simultaneously stabilized by solid hydrophobic silica nanospheres and hydrophilic soft PNIPAM microgel.

A general drawback of microgels is that they do not stabilize water-in-oil (w/o) emulsions of non-polar oils. Simultaneous stabilization with solid hydrophobic nanoparticles and soft hydrophilic microgels overcomes this problem. For a fundamental understanding of this synergistic effect the use of well defined particle systems is crucial. Therefore, the present study investigates the stabilization of water droplets in a highly non-polar oil phase using temperature responsive, soft and hydrophilic PNIPAM microgel particles (MGs) and solid and hydrophobic silica nanospheres (SNs) simultaneously. The SNs are about 20 times smaller than the MGs. In a multiscale approach the resulting emulsions are studied from the nanoscale particle properties over microscale droplet sizes to macroscopic observations. The synergy of the particles allows the stabilization of water-in-oil (w/o) emulsions, which was not possible with MGs alone, and offers a larger internal interface than the stabilization with SNs alone. Furthermore, the incorporation of hydrophilic MGs into a hydrophobic particle layer accelerates the emulsions sedimentation speed. Nevertheless, the droplets are still sufficiently protected against coalescence even in the sediment and can be redispersed by gentle shaking. Based on droplet size measurements and cryo-SEM studies we elaborate a model, which explains the found phenomena.

Self-templating construction of hollow Fe-CoxP nanospheres for oxygen evolution reaction

Rational design of catalysts with well-controlled structures and compositions has been demonstrated effective to optimize the electrochemical performance. Metal-organic frameworks (MOFs) with tunable composition, morphology as well as porous structure are desirable for constructing various functional materials acting as precursors. In this work, a facile self-templating strategy is developed to synthesize hollow Fe-CoxP nanospheres. The solid Co-glycerate nanospheres are synthesized and used as self-sacrificing templates, which are converted to Co-Fe Prussian blue analogue (PBA) via an anion-exchange process by reacting with K3[Fe(CN)6] at room temperature, and then followed by phosphorization treatment to produce the Fe-CoxP. The transformation process endows the resultant product not only the hollow nanostructure, but also Fe atoms doping into the CoxP. By taking advantages of structural and compositional benefits as well as improved conductivity, the Fe-CoxP exhibits excellent electrocatalytic activity and stability toward the oxygen evolution reaction (OER), reaching the current density of 10 mA cm−2 at an overpotential of 300 mV. The post-OER catalyst is carefully characterized and the results indicate the phase transformation of the crystalline Fe-CoxP to the amorphous FeCo (oxy)hydroxides acting as the catalytically active species. The novel self-templating strategy avoids the challenge from the removal of the template, which can possibly be employed to produce a sequence of PBA-based functional nanomaterials for applications in electrochemical energy conversion and storage.

Physicochemical characteristics of calcined MnFe2O4 solid nanospheres and their catalytic activity to oxidize para-nitrophenol with peroxymonosulfate and n-C7 asphaltenes with air

Manganese ferrite solid nanospheres (MSNs) were prepared by a solvothermal method and calcined at various temperatures up to 500 °C. Their surface area, morphology, particle size, weight change during calcination, surface coordination number of metal ions, oxidation state, crystal structure, crystallite size, and magnetic properties were studied. The MSNs were used as catalysts to activate potassium peroxymonosulfate (PMS) for the oxidative degradation of para-nitrophenol (PNP) from water and for the oxidation of n-C7 asphaltenes in flowing air at atmospheric (0.084 MPa) and high pressure (6 MPa). Mn was in oxidation states (II) and (III) at calcination temperature of 200 °C, and the crystalline structure corresponded to jacobsite. Mn was in oxidation states (III) and (IV) at 350 °C and in oxidation states (II), (III), and (IV) at 500 °C, and the crystalline structure was maghemite at both temperatures. MSN catalysts generated hydroxyl (HO·) and sulfate (SO4·-) radicals in the PMS activation and generated HO· radicals in the n-C7 asphaltene oxidation. In both reactions, the best catalyst was MSN calcined at 350 °C (MSN350), because it has the highest concentration of Mn(III) in octahedral B sites, which are directly exposed to the catalyst surface, and the largest total and lattice oxygen contents, favoring oxygen mobility for Mn redox cycles. The MSN350 sample reduces the decomposition temperature of n-C7 asphaltenes from 430 to 210 °C at 0.084 MPa and from 370 to 200 °C at 6.0 MPa. In addition, it reduces the effective activation energy by approximately 77.6% in the second combustion (SC) region, where high-temperature oxidation reactions take place.

Femtosecond-Laser-Induced Saturable Absorption and Optical Limiting of Hollow Silver Nanocubes: Implications for Optical Switching and Bioimaging

The effects of shape, size, and surface plasmon resonance (SPR) peak position (λSPR) on nonlinear absorption (NLA) were investigated at 808 nm, using a femtosecond laser. We found that NLA behavior is the result of competition between saturable absorption (SA) and reverse saturable absorption (RSA). SA behavior, i.e., optical transparency in silver nanocrystals, is introduced by the change in shape and structure from solid nanospheres to hollow nanocubes. For the latter, SA behavior dominates at low input irradiance, while RSA dominates at higher laser powers. A series of hollow silver nanocubes (HAgNCs) was synthesized that exhibit SPR peaks at 510, 550, 590, and 630 nm, hence named as HAgNC-510, HAgNC-550, HAgNC-590, and HAgNC-630, respectively. The edge lengths (l) of HAgNC-510, HAgNC-550, HAgNC-590, and HAgNC-630 were determined to be 33 ± 4, 45 ± 8, 70 ± 10, and 100 ± 15 nm. The switching of SA to RSA occurred at lower laser power for larger HAgNCs as compared to the smaller ones. The saturation intensity (Isat) was found to vary linearly with the size of HAgNCs. Moreover, for a four-times rise in input pulse intensity (63 → 252 GW/cm2), a huge increase of 3650% in the NLA coefficient, βeff, was observed for HAgNC-590, whereas merely 19% increase was found for the solid silver nanoparticles (SAgNP-400). The extraordinary enhancement in βeff is attributed to the enhanced electric field at the sharp edges and corners of the nanocubes. The red-tailing of SPR peaks also had a significant effect on the values of βeff. The outcomes, i.e., optical transparency and SA–RSA switching, will open vistas for a variety of diverse applications such as optical switching, limiting, and bioimaging.

Solvent-Controlled Topological Evolution from Nanospheres to Superhelices.

Supramolecular assemblies with diverse morphologies are crucial in determining their biochemical or physical properties. However, the topological evolution and self-assembly intermediates as well as the mechanism remain elusive. Herein, a dynamic morphological evolution from solid nanospheres to superhelical nanofibers is revealed via self-assembly of a minimal l-tryptophan-based derivative (LPWM) with various mixed solvent combinations, including the formation of solid nanospheres, the fusion of nanospheres into pearling necklace, the disintegration of necklace into short nanofibers, the distortion of nanofibers into nanotwists, and the entanglement of nanotwists into superhelices. It is found that the breakage of intramolecular H-bonds and reconstruction of intermolecular H-bonds, as well as the variation of aromatic interactions and hydrophobic effects, are the key driving forces for topological transformation, especially the dimensional evolution. The nanospheres and nanofibers demonstrate discrepant behaviors towards mouse neural stem cell (NSC) differentiation that compared with negligible impact of nanospheres scaffold, the nanofibers scaffold is favorable for NSC differentiation into neurons. The remarkable dynamic regulation of assembly process, together with the NSC differentiation on twisted nanofibers are making this system an ideal model to interpret complex proteins fibrillation processes and investigate the structure-function relationship.

Preparations of NiFe2O4 Yolk-Shell@C Nanospheres and Their Performances as Anode Materials for Lithium-Ion Batteries.

At present, lithium-ion batteries (LIBs) have received widespread attention as substantial energy storage devices; thus, their electrochemical performances must be continuously researched and improved. In this paper, we demonstrate a simple self-template solvothermal method combined with annealing for the synthesis of NiFe2O4 yolk-shell (NFO-YS) and NiFe2O4 solid (NFO-S) nanospheres by controlling the heating rate and coating them with a carbon layer on the surface via high-temperature carbonization of resorcinol and formaldehyde resin. Among them, NFO-YS@C has an obvious yolk-shell structure, with a core-shell spacing of about 60 nm, and the thicknesses of the NiFe2O4 shell and carbon shell are approximately 15 and 30 nm, respectively. The yolk-shell structure can alleviate volume changes and shorten the ion/electron diffusion path, while the carbon shell can improve conductivity. Therefore, NFO-YS@C nanospheres as the anode materials of LIBs show a high initial capacity of 1087.1 mA h g−1 at 100 mA g−1, and the capacity of NFO-YS@C nanospheres impressively remains at 1023.5 mA h g−1 after 200 cycles at 200 mA g−1. The electrochemical performance of NFO-YS@C is significantly beyond NFO-S@C, which proves that the carbon coating and yolk-shell structure have good stability and excellent electron transport ability.

Cavitating inside spherical boron nitride nanoparticles dependent on controllably follow-up treated atmospheres

A novel two-step method is developed for the facile preparation of hollow nano-spherical boron nitride (BN). BN nanospheres prepared by the traditional chemical vapor deposition reaction of ammonia and trimethyl borate were hollowed out. The average size of solid BN nanospheres precursor was ~ 130 nm. Boron nitride phase, morphology, and surface functionalization characterization along with the measurement of O content, and surface functionality were used to illustrate the final differences among various cavitating BN nanospheres treated with different gas flows at a higher temperature. Several possible formation mechanisms for the BN cavitating structures were proposed. This work provides direction for the controllable preparation of hollow-type BN particles.