Herein,we report the design and synthesis of alternating donor-acceptor nanorings[3]C-NA and[4]C-NA,along with a reference linear molecule[3]L-NA,via electrochemical oxidation-induced reductive elimination of alkynyl ...Herein,we report the design and synthesis of alternating donor-acceptor nanorings[3]C-NA and[4]C-NA,along with a reference linear molecule[3]L-NA,via electrochemical oxidation-induced reductive elimination of alkynyl platinum(II)complexes.Unlike[3]L-NA,which exhibits charge defects at its end-groups,the cyclic structures of[3]C-NA and[4]C-NA facilitate enhanced electron delocalization,enabling efficient charge transfer in low-polarity toluene.In the polar solvent dichloromethane(DCM),the increased flexibility of[4]C-NA promotes intramolecular charge transfer and suppresses charge recombination.The observed faster intramolecular charge transfer and slower charge recombination rates in these nanoring acceptor materials suggest their potential for improving the power conversion efficiency of organic solar cells,providing valuable insights for the design of nanoring acceptor materials.展开更多
As a semiconductor material with a 2 D-laminate structure, g-C_(3)N_(4)(bandwidth 2.7 e V) has a similar structure and excellent performance to graphene. However, high surface energy and photogenerated e–h recombinat...As a semiconductor material with a 2 D-laminate structure, g-C_(3)N_(4)(bandwidth 2.7 e V) has a similar structure and excellent performance to graphene. However, high surface energy and photogenerated e–h recombination of g-C_(3)N_(4)seriously hinder its application in the field of marine anticorrosion and antifouling.To solve these problems, we synthesized the g-C_(3)N_(4)nanosheets decorated with Zn O nanoring via chemical etching technology. Whether the NR Zn O-CNNs have surface protection performance among the pure EP on the corrosion protection for metal substrate were investigated. The antifouling properties NR Zn OCNNs hybrid were also estimated through photocatalytic bacterial and algae resistance tests. Combined with the electrochemical results, it was found that the impedance modulus of NR Zn O-CNNs/EP within 45 days showed two orders of magnitude higher than that of pure EP in the 3.5 wt% Na Cl solution. Besides, Local electrochemical impedance spectroscopy(LEIS) further explored the anticorrosion behavior of NR Zn O-CNNs/EP coating, which indicated that the NR Zn O-CNNs/EP coating with a scratch maintained an excellent corrosion resistance between 0–24 h. Under the visible light conditions, the lifetime of photogenerated e–h was prolonged due to the formation of NR Zn O-CNNs heterojunction structure, it was observed that the antibacterial rate against Bacillus subtilis reached 100% within 8 h. An Antialgae test was performed on chlorella seawater solution, which indicated that 5 mg/m L of NR Zn O-CNNs hybrid could make chlorella sharply reduce within 4 days. Simultaneously, the corrosion protection and photocatalytic antifouling mechanisms of NR Zn O-CNNs were proposed, thus it provided a broader platform for the design of versatile marine protection materials.展开更多
Rationally engineering the microstructure and electronic structure of catalysts to induce high activity for versatile applications remains a challenge. Herein, chlorine doped graphitic carbon nitride(Cl-doped g-C3N4) ...Rationally engineering the microstructure and electronic structure of catalysts to induce high activity for versatile applications remains a challenge. Herein, chlorine doped graphitic carbon nitride(Cl-doped g-C3N4) nanorings have been designed as a superior photocatalyst for pollutant degradation and oxygen evolution reaction(OER). Remarkably, Cl-doped g-C3N4 nanorings display enhanced OER performance with a small overpotential of approximately 290 m V at current density of 10 m A cm^-2 and Tafel slope of 83 m V dec-1, possessing comparable OER activity to precious metal oxides RuO2 and IrO2/C. The excellent catalytic performance of Cl-doped g-C3N4 nanorings originates from the strong oxidation capability,abundant active sites exposed and efficient charge transfer. More importantly, visible light irradiation gives rise to a prominent improvement of the OER performance, reducing the OER overpotential and Tafel slope by 140 m V and 28 m V dec^-1, respectively, demonstrating the striking photo-responsive OER activity of Cl-doped g-C3N4 nanorings. The great photo-induced improvement in OER activity would be related to the efficient charge transfer and the·OH radicals arising spontaneously on CN-Cl100 catalyst upon light irradiation. This work establishes Cl-doped g-C3N4 nanorings as a highly competitive metal-free candidate for photoelectrochemical energy conversion and environmental cleaning application.展开更多
Effective utilization of hot electrons generated from the decay of surface plasmon resonance in metal nanoparticles is conductive to improve solar water splitting efficiency.Herein,Ag nanoparticles and reduced graphen...Effective utilization of hot electrons generated from the decay of surface plasmon resonance in metal nanoparticles is conductive to improve solar water splitting efficiency.Herein,Ag nanoparticles and reduced graphene oxide(rGO)co-decorated hierarchical TiO2 nanoring/nanotube arrays(TiO2 R/T)were facilely fabricated by using two-step electrochemical anodization,electrodeposition,and photoreduction methods.Comparative studies were conducted to elucidate the effects of rGO and Ag on the morphology,photoresponse,charge transfer,and photoelectric properties of TiO2.Firstly,scanning electron microscope images confirm that the Ag nanoparticles adhered on TiO2 R/T and TiO2 R/T-rGO have similar diameter of 20 nm except for TiO2 R-rGO/T.Then,the UV-Vis DRS and scatter spectra reveal that the optical property of the Ag-TiO2 R/T-rGO ternary composite is enhanced,ascribing to the visible light absorption of plasmonic Ag nanoparticles and the weakening effect of rGO on light scattering.Meanwhile,intensity-modulated photocurrent spectroscopy and photoluminescence spectra demonstrate that rGO can promote the hot electrons transfer from Ag nanoparticles to Ti substrate,reducing the photogenerated electron-hole recombination.Finally,Ag-TiO2 R/T-rGO photoanode exhibits high photocurrent density(0.98 mA cm?2)and photovoltage(0.90 V),and the stable H2 evolution rate of 413μL h?1 cm?2 within 1.5 h under AM 1.5 which exceeds by 1.30 times than that of pristine TiO2 R/T.In line with the above results,this work provides a reliable route synergizing rGO with plasmonic metal nanoparticles for photocatalysis,in which,rGO presents a broad absorption spectrum and effective photogenerated electrons transfer.展开更多
Monolayer-ordered gold nanoring arrays were prepared by ion-sputtering method and used as surface enhanced Raman spectroscopy(SERS)substrates to test the individual atmospheric aerosols particle.Compared to other meth...Monolayer-ordered gold nanoring arrays were prepared by ion-sputtering method and used as surface enhanced Raman spectroscopy(SERS)substrates to test the individual atmospheric aerosols particle.Compared to other methods used for testing atmospheric aerosols particles,the collection and subsequent detection in our work is performed directly on the gold nanoring SERS substrate without any treatment of the analyte.The SERS performance can be tuned by changing the depth of the gold nanoring cavity as originating from coupling of dipolar modes at the inner and outer surfaces of the nanorings.The electric field exhibits uniform enhancement and polarization in the ordered Au nanoring substrate,which can improve the accuracy for detecting atmospheric aerosol particles.Combined with Raman mapping,the information about chemical composition of individual atmospheric aerosols particle and distribution of specific components can be presented visually.The results show the potential of SERS in enabling improved analysis of aerosol particle chemical composition,mixing state,and other related physicochemical properties.展开更多
Hierarchical CdCO3 nanostructures with complex morphologies, such as tetragonal, pentagonal and hexagonal nanorings, can be prepared via self-assembly of nanocrystals in a solvothermal environment. XRD pattern indicat...Hierarchical CdCO3 nanostructures with complex morphologies, such as tetragonal, pentagonal and hexagonal nanorings, can be prepared via self-assembly of nanocrystals in a solvothermal environment. XRD pattern indicated that the product is trigonal CdCO3 phase （PDF#850989） with cell constants a = 6.112 A and a = 47.4°. Based on our experimental results, a possible nanoring formation mechanism was proposed.展开更多
With the purpose of searching for a convenient process to synthesize nanoparticles with special structure,a simple solid-state reaction in the presence of nonionic surfactant OP-10 at room temperature was adopted to p...With the purpose of searching for a convenient process to synthesize nanoparticles with special structure,a simple solid-state reaction in the presence of nonionic surfactant OP-10 at room temperature was adopted to prepare copper nitrate hydroxide(Cu_(2)(OH)_(3)NO_(3))nanorings with an average internal diameter of 250 nm and average wall thickness of 100 nm.The formation of Cu_(2)(OH)_(3)NO_(3) nanorings has a close relation with OP-10.Transmission electron microscopy(TEM),field emission scanning electron microscopy(FESEM),thermogravimetric analysis(TGA)and X-ray diffractometry(XRD)were used to characterize the obtained nanorings.The UV-Vis spectrum shows that the optical property of Cu_(2)(OH)_(3)NO_(3) nanorings is similar to that of CuO or CuS.The synthesis method used here proves both simplicity and high efficiency.展开更多
On the basis of the growth mechanism of a GaAs/InAs nanoring, we propose a fine model which reflects the confinement details of real nanoring. Through calculations of the two-electron energy and far-infrared （FIR） s...On the basis of the growth mechanism of a GaAs/InAs nanoring, we propose a fine model which reflects the confinement details of real nanoring. Through calculations of the two-electron energy and far-infrared （FIR） spectra, we find that the ring topological structure and electron-electron interaction have great influence on the FIR spectra. The two unknown transition peaks in the experiment are determined theoretically. The theoretical results are in good agreement with the experiments.展开更多
The aggregated nanorings of EuF3 were synthesized via ultrasonic irritation in aqueous solution. The products were characterized by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM）, and transmiss...The aggregated nanorings of EuF3 were synthesized via ultrasonic irritation in aqueous solution. The products were characterized by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. XRD pattern proved that the crystalline phase of the EuF3 rings was hexagonal. The SEM and TEM images indicated that the as-prepared EuF3 nanocrystals had ring-like morphology and were aggregated by numerous small crystallites （about 10-15 nm in diameter）; the outer diameter of the rings was in the range of 200--300 nm, while the inner diameter was in the range of 50-80 nm with a thickness of 30-40 nm. Moreover, the time-depend experiments were carried out to disclose the formation mechanism of the as-prepared ring-like nanostructures.展开更多
Recent discoveries in the synthesis and applications of magnetic vortex nanorings/nanodiscs in theranostic applications are reviewed. First, the principles of nanomagnetism and magnetic vortex are introduced. Second, ...Recent discoveries in the synthesis and applications of magnetic vortex nanorings/nanodiscs in theranostic applications are reviewed. First, the principles of nanomagnetism and magnetic vortex are introduced. Second, methods for producing magnetic vortex nanorings/nanodiscs are presented. Finally, theranostic applications of magnetic vortex nanorings/nanodiscs are addressed.展开更多
The persistent current in three-dimensional （P × N2） nanorings as a function of the unit cell number （P）, the channel number （M =N2）, surface disorder （ζ）, and temperature （T） is theoretically investig...The persistent current in three-dimensional （P × N2） nanorings as a function of the unit cell number （P）, the channel number （M =N2）, surface disorder （ζ）, and temperature （T） is theoretically investigated in terms of rotational symmetry. On the whole, the typical current increases linearly with √M but decreases exponentially with P, while wide fluctuations exist therein. In the presence of surface disorder, the persistent current decreases with ζ in the regime of weak disorder but increases in the regime of strong disorder. In addition, it is found that the persistent current in perfect rings decreases exponentially with temperature even at T 〈 T＊, while in most disorder rings, the typical current decreases slightly with temperature at T 〈 T＊.展开更多
Photodynamic therapy(PDT)and photothermal therapy(PTT)synergistic treatment for hypoxic tumors,always requires highintensity light irradiation.This study introduces an intramolecular modulation approach for achieving ...Photodynamic therapy(PDT)and photothermal therapy(PTT)synergistic treatment for hypoxic tumors,always requires highintensity light irradiation.This study introduces an intramolecular modulation approach for achieving PDT and PTT synergy under gentle light irradiation via the formation of tightly packed J-aggregated nanorings.Specifically,cyanine dyes,designated as TYA and TYB,were synthesized and compared to investigate the influence of intramolecular and intermolecular forces on the formation of compact J-aggregates.Compared to TYA(14.22°,8.58Å),the planar quinoline moieties in TYB exhibit a more pronounced rotation around the methylene linker(50.21°),which facilitates intermolecular slippage and reduces the stacking distance to 4.91Åin J-aggregated nanorings(TYB J-NPs).The smaller monomer separations facilitate the generation of photothermal effects under mild light irradiation.These TYB J-NPs generate reactive oxygen species(ROS)levels comparable to those produced by TYA J-aggregates,while simultaneously producing a thermal effect under near-infrared(NIR)light irradiation(35 mW/cm^(2),10 min,ΔT>20℃).This dual functionality synergistically enables in vivo fluorescence and photothermal imaging,and effectively inhibits the growth and invasion of 4T1 tumors in mice.Moreover,TYB J-NPs demonstrate substantial antibacterial efficacy against both Gram-positive and Gram-negative bacteria,thereby offering effective antibacterial protection during tumor phototherapy.In summary,the intramolecular twisting of TYB effectively resolves the bottleneck associated with intermolecular repulsions at large molecular separations,thereby facilitating the formation of densely packed J-aggregates.This represents the first instance where J-aggregated nanorings enable concurrent PDT and PTT with antibacterial effectiveness under low-density NIR light irradiation.This work may significantly enhance the therapeutic potential of cyanine dyes in cancer treatment,pathogenic bacterial infections,and other diseases.展开更多
CONSPECTUS:Topologically unique nanocarbon materials with optoelectronic potential are both fascinating and challenging synthetic targets.Their distinctive molecular topologies often lead to chirality,unique optoelect...CONSPECTUS:Topologically unique nanocarbon materials with optoelectronic potential are both fascinating and challenging synthetic targets.Their distinctive molecular topologies often lead to chirality,unique optoelectronic properties,and encapsulation capabilities,stimulating advances in synthetic chemistry and materials science.The research on curved nanocarbon materials has garnered substantial interest due to the intricate relationship between theirπ-conjugation and molecular geometry,as well as their emerging applications in various fields.The introduction of curvature significantly affects the redox behaviors,optical properties,charge-transport capabilities,and self-assembly processes of these nanocarbon materials.The representative examples of curved aromatic systems are cycloparaphenylenes(CPPs)and related carbon nanorings.In these molecules,the nonplanar aromatic structures can induce unique radialπ-conjugation and further endow them with distinctive photophysical properties.By adjusting the number of benzene rings in a CPP or incorporating diverse polycyclic aromatic hydrocarbon units,researchers can finely tune the optical and electronic properties of these nanostructures.Many potential applications can be discovered in the fields of fluorescent probes,organic light-emitting diodes(OLEDs),and optoelectronic devices.These properties establish CPP as an important scaffold to create novel carbon nanostructures.With the ongoing advancements in molecular topology,new opportunities are emerging within the fields of materials science,molecular electronics,and biomedicine.Given the exceptional electronic and photophysical properties of CPPs,there has been considerable interest in the development of topologically intriguing bis/multimacrocyclic architectures.It is anticipated that high dimensionality and unexplored topologies will endow these bis/multimacrocycles with unparalleled physical and chemical properties.This concise Account highlights recent developments from our research group on topologically functional materials based on CPP carbon nanorings,particularly their potential applications.Our discussion focuses on(i)the design and synthesis of a series of fully sp2-hybridized all-benzenoid bismacrocycles,as well as[n]cycloparaphenylene-pillar[5]arene bismacrocycles;(ii)the construction of all-CPP-based longπ-extended polymeric segments of the armchair SWCNT;and(iii)the synthesis of CPP-based mechanically interlocked molecules,specifically[12]CPP-[3]catenane.Structures like these CPP-based bis/multimacrocyclic architectures exhibit distinct properties-including radialπ-conjugation,supramolecular properties,chirality,and unexpected dualemissive and anti-Kasha photophysical characteristics due to their nonplanar geometries-that allow precise tuning of their HOMO−LUMO gap,emission profiles,and charge-transport behaviors.These properties make them promising for applications in OLEDs,circularly polarized luminescence(CPL)materials,lithium-ion batteries(LIBs),and photoelectroactive devices.By discussing recent work,we demonstrate the potential of these carbon nanorings for future technologies in optoelectronics,chiroptics,and nanotechnology.We also discuss challenges and future directions,emphasizing the importance of precise control over the size,shape,and conjugation of these topological structures to broaden their applications in molecular machines,sensors,and functional materials.展开更多
We report the preparation of nanocomposites of reduced graphene oxide with embedded Fe3O4/Fe nanorings （FeNR@rGO） by chemical hydrothermal growth. We illustrate the use of these nanocomposites as novel electromagnet...We report the preparation of nanocomposites of reduced graphene oxide with embedded Fe3O4/Fe nanorings （FeNR@rGO） by chemical hydrothermal growth. We illustrate the use of these nanocomposites as novel electromagnetic wave absorbing materials. The electromagnetic wave absorption properties of the nanocomposites with different compositions were investigated. The preparation procedure and nanocomposite composition were optimized to achieve the best electromagnetic wave absorption properties. Nanocomposites with a GO：cx-Fe203 mass ratio of 1：1 prepared by annealing in HdAr for 3 h exhibited the best properties. This nanocomposite sample （thickness = 4.0 mm） showed a minimum reflectivity of -23.09 dB at 9.16 GHz. The band range was 7.4-11.3 GHz when the reflectivity was less than -10 dB and the spectrum width was up to 3.9 GHz. These figures of merit are typically of the same order of magnitude when compared to the values shown by traditional ferric oxide materials. However, FeNR@rGO can be readily applied as a microwave absorbing material because the production method we propose is highly compatible with mass production standards.展开更多
The design of highly active and stable RuO_(2)-based nanostructures for acidic oxygen evolution reaction(OER)is extremely important for the development of water electrolysis technology,yet remains great challenges.We ...The design of highly active and stable RuO_(2)-based nanostructures for acidic oxygen evolution reaction(OER)is extremely important for the development of water electrolysis technology,yet remains great challenges.We here demonstrate that the incorporation of S into RuCuO nanorings(NRs)can significantly enhance the acidic OER performance.Experimental investigations show that the incorporation of S can optimize the interaction of Ru and O,and therefore significantly suppresses the dissolution of Ru in acidic condition.The optimized catalyst(SH-RuCuO NRs)displays superior OER performance to the commercial RuO_(2)/C.Impressively,the SH-RuCuO NRs can exhibit significantly enhanced stability for 3,000 cycles of cyclic voltammetry test and more than 250 h chronopotentiometry test at 10 mA·cm^(-2)in 0.5 M H_(2)SO_(4).This work highlights a potential strategy for designing active and stable RuO_(2)-based electrocatalysts for acidic OER.展开更多
In this paper, we report a new strategy for the fabrication of gold nanoring arrays via colloidal lithography and polymer-assisted self-assembly of gold nanoparticles （Au NPs）. First, multi-segmented polymer nanorod...In this paper, we report a new strategy for the fabrication of gold nanoring arrays via colloidal lithography and polymer-assisted self-assembly of gold nanoparticles （Au NPs）. First, multi-segmented polymer nanorod arrays were fabricated via colloidal lithography. They were then used as templates for Au NP adsorption, which resulted in nanoparticles on the poly（4-vinyl pyridine） （P4VP） segments. Continuous gold nanorings were formed after electroless deposition of gold. The diameter, quantity, and spacing of the gold nanorings could be tuned. Three dimensional coaxial gold nanorings with varying diameters could be fabricated on a polymer nanorod by modifying the etch parameters. The nanorings exhibited optical plasmonic resonances at theoretically predicted wavelengths. In addition, the polymer-assisted gold nanorings were released from the substrate to generate a high yield of flee-standing nanorings. This simple, versatile method was also used to prepare nanorings from other metals such as palladium.展开更多
Gold nanoring arrays are widely applied in various fields benefitting from their localized surface plasmon resonance(LSPR)properties.A key advantage of gold nanoring arrays is that the dipole resonance peak can be sys...Gold nanoring arrays are widely applied in various fields benefitting from their localized surface plasmon resonance(LSPR)properties.A key advantage of gold nanoring arrays is that the dipole resonance peak can be systematically tuned by changing the dimensions of gold nanoring arrays.However,most of the currently reported methods for preparing gold nanoring arrays cannot conveniently control the heights of the nanorings at a low cost.Here we introduce a facile method for preparing gold nanoring arrays with tunable plasmonic resonances using colloidal lithography.The dimensions of the nanorings including diameters,lattice constants,even the heights of the nanorings can be conveniently varied.Fourier transform near-infrared(FT-NIR)absorption spectroscopy was used to obtain the plasmonic resonance spectra of the nanoring arrays.All the prepared gold nanoring arrays exhibited a strong NIR or infrared(IR)plasmonic resonance which can be tuned by varying the nanoring dimensions.This versatile method can also be used to fabricate other types of plasmonic nanostructures,such as gold nanocone arrays.The obtained gold nanoring arrays as well as nanocone arrays may have potential applications in surface-enhanced spectroscopy or plasmonic sensing.展开更多
Radioactive wastewater containing high concentration of radionuclides poses severe threats to ecosystem and human health,so efficient removal of these toxic heavy metals is urgently needed.Titanate nanomaterials have ...Radioactive wastewater containing high concentration of radionuclides poses severe threats to ecosystem and human health,so efficient removal of these toxic heavy metals is urgently needed.Titanate nanomaterials have been demonstrated good adsorbents for heavy metals due to ion exchange property.In this study,titanate nanorings(TNRs)were synthesized using the facile hydrothermal-cooling method.The TNRs were composed of sodium trititanate,with a chemical formula of Na_(0.66)H_(1.34)-Ti_(3)O_(7)·0.27H_(2)O and a Na content of 2.38 mmol/g.The TNRs demonstrated sufficient adsorption performance to radionuclides europium(Eu)and uranium(U)ions.Specifically,even at a high initial concentration of 50 mg/L,86.5% and 92.6% of the two metal ions can be rapidly adsorbed by the TNRs within 5 min,and equilibrium was reached within 60 min at pH 5.The maximum adsorption capacity(Qmax)obtained by the Langmuir isotherm model was 115.3 mg/g for Eu(Ⅲ)and 282.5 mg/g for uranium U(Ⅵ)at pH 5,respectively.The adsorption capacities of the two metals under various water chemical conditions were highly related to their species.Ion exchange between metal cations and Na^(+) in the TNR interlayers was the dominant adsorption mechanism,and adsorption of U(Ⅵ)was more complicated because of the co-existence of various uranyl(UO_(2)^(2+))and uranyl-hydroxyl species.The spent TNRs were effectively regenerated through an acid-base or ethylenediamine tetraacetic acid(EDTA)treatment and reused.Considering the large adsorption capacity and quick kinetic,TNRs are promising materials to remove radionuclides in environmental purification applications,especially emergent treatment of leaked radionuclides.展开更多
Porous graphitic carbon nanorings(PGCNs)are proposed by smart catalytic graphitization of nano-sized graphene quantum dots(GQDs).The as-prepared PGCNs show unique ring-like morphology with diameter around 10 nm,and de...Porous graphitic carbon nanorings(PGCNs)are proposed by smart catalytic graphitization of nano-sized graphene quantum dots(GQDs).The as-prepared PGCNs show unique ring-like morphology with diameter around 10 nm,and demonstrate extraordinary mesoporous structure,controllable graphitization degree and highly defective nature.The mechanism from GQDs to PGCNs is proven to be a dissolution-precipitation process,undergoing the procedure of amorphous carbon,intermediate phase,graphitic carbon nanorings and graphitic carbon nanosheets.Further,the relationship between particles size of GQDs precursor and graphitization degree of PGCNs products is revealed.The unique microstructure implies PGCNs a broad prospect for energy storage application.When applied as negative electrode materials in dual-carbon lithium-ion capacitors,high energy density(77.6 Wh·kg^(−1))and super long lifespan(89.5%retention after 40,000 cycles at 5.0 A·g^(−1))are obtained.The energy density still maintains at 24.5 Wh·kg^(−1)even at the power density of 14.1 kW·kg^(−1),demonstrating excellent rate capability.The distinct microstructure of PGCNs together with the strategy for catalytic conversion from nanocarbon precursors to carbon nanorings opens a new window for carbon materials in electrochemical energy storage.展开更多
As an ideal high-density storage unit,magnetic nanorings have become a research hotspot in recent years.We can both study the evolution of microscopic state of magnetization and acquire macroscopic magnetic properties...As an ideal high-density storage unit,magnetic nanorings have become a research hotspot in recent years.We can both study the evolution of microscopic state of magnetization and acquire macroscopic magnetic properties by micromagnetic simulation,which has thus been widely used.However,traditional micromagnetism cannot simulate complex stress state.Due to the introduction of microelasticity theory,the phase field method for magnetic materials can be used to calculate the coupling effect of stress and magnetic field.However,the computing model usually needs to satisfy periodic boundary condition.In this paper,the phase field simulation combined with the finite element method is employed.By using user defined element,the evolution of magnetic domain structures of the double-hole nanorings has been studied.In different diameter of the holes and external magnetic field direction,we have found seven kinds of magnetic domain evolution mechanism.Among them,the twin-vortex evolution mechanism with high stability and low demagnetization interference characteristics of advantages,has good application prospect in magnetic random-access memory(MRAM)unit.展开更多
基金support from Natural Science Foundation of China(Nos.22271239,22171237,22071208,and 92356308)the Natural Science Foundation of Fujian Province(2022J01524)。
文摘Herein,we report the design and synthesis of alternating donor-acceptor nanorings[3]C-NA and[4]C-NA,along with a reference linear molecule[3]L-NA,via electrochemical oxidation-induced reductive elimination of alkynyl platinum(II)complexes.Unlike[3]L-NA,which exhibits charge defects at its end-groups,the cyclic structures of[3]C-NA and[4]C-NA facilitate enhanced electron delocalization,enabling efficient charge transfer in low-polarity toluene.In the polar solvent dichloromethane(DCM),the increased flexibility of[4]C-NA promotes intramolecular charge transfer and suppresses charge recombination.The observed faster intramolecular charge transfer and slower charge recombination rates in these nanoring acceptor materials suggest their potential for improving the power conversion efficiency of organic solar cells,providing valuable insights for the design of nanoring acceptor materials.
基金the Zhejiang Provincial Natural Science Foundation of China (LR21E050001)the Youth Innovation Promotion Association,CAS (2017338)+1 种基金the National Key Basic Research Program of China (973) (2014CB643305)Natural Science Foundation of Ningbo (202003N4357)。
文摘As a semiconductor material with a 2 D-laminate structure, g-C_(3)N_(4)(bandwidth 2.7 e V) has a similar structure and excellent performance to graphene. However, high surface energy and photogenerated e–h recombination of g-C_(3)N_(4)seriously hinder its application in the field of marine anticorrosion and antifouling.To solve these problems, we synthesized the g-C_(3)N_(4)nanosheets decorated with Zn O nanoring via chemical etching technology. Whether the NR Zn O-CNNs have surface protection performance among the pure EP on the corrosion protection for metal substrate were investigated. The antifouling properties NR Zn OCNNs hybrid were also estimated through photocatalytic bacterial and algae resistance tests. Combined with the electrochemical results, it was found that the impedance modulus of NR Zn O-CNNs/EP within 45 days showed two orders of magnitude higher than that of pure EP in the 3.5 wt% Na Cl solution. Besides, Local electrochemical impedance spectroscopy(LEIS) further explored the anticorrosion behavior of NR Zn O-CNNs/EP coating, which indicated that the NR Zn O-CNNs/EP coating with a scratch maintained an excellent corrosion resistance between 0–24 h. Under the visible light conditions, the lifetime of photogenerated e–h was prolonged due to the formation of NR Zn O-CNNs heterojunction structure, it was observed that the antibacterial rate against Bacillus subtilis reached 100% within 8 h. An Antialgae test was performed on chlorella seawater solution, which indicated that 5 mg/m L of NR Zn O-CNNs hybrid could make chlorella sharply reduce within 4 days. Simultaneously, the corrosion protection and photocatalytic antifouling mechanisms of NR Zn O-CNNs were proposed, thus it provided a broader platform for the design of versatile marine protection materials.
基金supported financially by the National Natural Science Foundation of China (Nos. 51772085, 51471068 and U1530151)Large instrument fund of Hunan University
文摘Rationally engineering the microstructure and electronic structure of catalysts to induce high activity for versatile applications remains a challenge. Herein, chlorine doped graphitic carbon nitride(Cl-doped g-C3N4) nanorings have been designed as a superior photocatalyst for pollutant degradation and oxygen evolution reaction(OER). Remarkably, Cl-doped g-C3N4 nanorings display enhanced OER performance with a small overpotential of approximately 290 m V at current density of 10 m A cm^-2 and Tafel slope of 83 m V dec-1, possessing comparable OER activity to precious metal oxides RuO2 and IrO2/C. The excellent catalytic performance of Cl-doped g-C3N4 nanorings originates from the strong oxidation capability,abundant active sites exposed and efficient charge transfer. More importantly, visible light irradiation gives rise to a prominent improvement of the OER performance, reducing the OER overpotential and Tafel slope by 140 m V and 28 m V dec^-1, respectively, demonstrating the striking photo-responsive OER activity of Cl-doped g-C3N4 nanorings. The great photo-induced improvement in OER activity would be related to the efficient charge transfer and the·OH radicals arising spontaneously on CN-Cl100 catalyst upon light irradiation. This work establishes Cl-doped g-C3N4 nanorings as a highly competitive metal-free candidate for photoelectrochemical energy conversion and environmental cleaning application.
基金the National Natural Science Foundation of China(Grant No.51776009)for the financial support.
文摘Effective utilization of hot electrons generated from the decay of surface plasmon resonance in metal nanoparticles is conductive to improve solar water splitting efficiency.Herein,Ag nanoparticles and reduced graphene oxide(rGO)co-decorated hierarchical TiO2 nanoring/nanotube arrays(TiO2 R/T)were facilely fabricated by using two-step electrochemical anodization,electrodeposition,and photoreduction methods.Comparative studies were conducted to elucidate the effects of rGO and Ag on the morphology,photoresponse,charge transfer,and photoelectric properties of TiO2.Firstly,scanning electron microscope images confirm that the Ag nanoparticles adhered on TiO2 R/T and TiO2 R/T-rGO have similar diameter of 20 nm except for TiO2 R-rGO/T.Then,the UV-Vis DRS and scatter spectra reveal that the optical property of the Ag-TiO2 R/T-rGO ternary composite is enhanced,ascribing to the visible light absorption of plasmonic Ag nanoparticles and the weakening effect of rGO on light scattering.Meanwhile,intensity-modulated photocurrent spectroscopy and photoluminescence spectra demonstrate that rGO can promote the hot electrons transfer from Ag nanoparticles to Ti substrate,reducing the photogenerated electron-hole recombination.Finally,Ag-TiO2 R/T-rGO photoanode exhibits high photocurrent density(0.98 mA cm?2)and photovoltage(0.90 V),and the stable H2 evolution rate of 413μL h?1 cm?2 within 1.5 h under AM 1.5 which exceeds by 1.30 times than that of pristine TiO2 R/T.In line with the above results,this work provides a reliable route synergizing rGO with plasmonic metal nanoparticles for photocatalysis,in which,rGO presents a broad absorption spectrum and effective photogenerated electrons transfer.
基金the National Natural Science Foundation of China(No.21976030 and No.21677037)the Natural Science Foundation of Shanghai(No.19ZR1471200 and No.17ZR1440200)。
文摘Monolayer-ordered gold nanoring arrays were prepared by ion-sputtering method and used as surface enhanced Raman spectroscopy(SERS)substrates to test the individual atmospheric aerosols particle.Compared to other methods used for testing atmospheric aerosols particles,the collection and subsequent detection in our work is performed directly on the gold nanoring SERS substrate without any treatment of the analyte.The SERS performance can be tuned by changing the depth of the gold nanoring cavity as originating from coupling of dipolar modes at the inner and outer surfaces of the nanorings.The electric field exhibits uniform enhancement and polarization in the ordered Au nanoring substrate,which can improve the accuracy for detecting atmospheric aerosol particles.Combined with Raman mapping,the information about chemical composition of individual atmospheric aerosols particle and distribution of specific components can be presented visually.The results show the potential of SERS in enabling improved analysis of aerosol particle chemical composition,mixing state,and other related physicochemical properties.
基金This work was supported by the the project of Nano-molecular Functional Materials of Fujian Province (2005HZ01-1)
文摘Hierarchical CdCO3 nanostructures with complex morphologies, such as tetragonal, pentagonal and hexagonal nanorings, can be prepared via self-assembly of nanocrystals in a solvothermal environment. XRD pattern indicated that the product is trigonal CdCO3 phase （PDF#850989） with cell constants a = 6.112 A and a = 47.4°. Based on our experimental results, a possible nanoring formation mechanism was proposed.
基金Project(IMPQ29080005)supported by the Natural Scientific Research Innovation Foundation in Harbin Institute of Technology,ChinaProject(IMJQ10070013)supported by the Research Foundation in Harbin Institute of Technology(Weihai),China。
文摘With the purpose of searching for a convenient process to synthesize nanoparticles with special structure,a simple solid-state reaction in the presence of nonionic surfactant OP-10 at room temperature was adopted to prepare copper nitrate hydroxide(Cu_(2)(OH)_(3)NO_(3))nanorings with an average internal diameter of 250 nm and average wall thickness of 100 nm.The formation of Cu_(2)(OH)_(3)NO_(3) nanorings has a close relation with OP-10.Transmission electron microscopy(TEM),field emission scanning electron microscopy(FESEM),thermogravimetric analysis(TGA)and X-ray diffractometry(XRD)were used to characterize the obtained nanorings.The UV-Vis spectrum shows that the optical property of Cu_(2)(OH)_(3)NO_(3) nanorings is similar to that of CuO or CuS.The synthesis method used here proves both simplicity and high efficiency.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11074025)the National Basic Research Program of China (Grant No. 2011CB922200)the China Academy of Engineering and Physics(‘909’)
文摘On the basis of the growth mechanism of a GaAs/InAs nanoring, we propose a fine model which reflects the confinement details of real nanoring. Through calculations of the two-electron energy and far-infrared （FIR） spectra, we find that the ring topological structure and electron-electron interaction have great influence on the FIR spectra. The two unknown transition peaks in the experiment are determined theoretically. The theoretical results are in good agreement with the experiments.
基金the National Natural Science Foundation of China (20571025)Henan Innovation Project for University Prominent Research Talents (2005KYCX005)
文摘The aggregated nanorings of EuF3 were synthesized via ultrasonic irritation in aqueous solution. The products were characterized by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. XRD pattern proved that the crystalline phase of the EuF3 rings was hexagonal. The SEM and TEM images indicated that the as-prepared EuF3 nanocrystals had ring-like morphology and were aggregated by numerous small crystallites （about 10-15 nm in diameter）; the outer diameter of the rings was in the range of 200--300 nm, while the inner diameter was in the range of 50-80 nm with a thickness of 30-40 nm. Moreover, the time-depend experiments were carried out to disclose the formation mechanism of the as-prepared ring-like nanostructures.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21376192 and 81571809)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20126101110017)MOE Ac RF Tier 2-MOE2011-T2-1-043 and A-Star SERC 1321202068
文摘Recent discoveries in the synthesis and applications of magnetic vortex nanorings/nanodiscs in theranostic applications are reviewed. First, the principles of nanomagnetism and magnetic vortex are introduced. Second, methods for producing magnetic vortex nanorings/nanodiscs are presented. Finally, theranostic applications of magnetic vortex nanorings/nanodiscs are addressed.
基金supported by the National Natural Science Foundation of China(Grant No i0674113)Program for New Century Excellent Talents in University of China(Grant No NCET-06-0707)+1 种基金Foundation for the Author of National Excellent Doctoral Dissertation of China(Grant No 200726)partially by Scientific Research Fund of Hunan Provincial Education Department of China (Grant No 06A071)
文摘The persistent current in three-dimensional （P × N2） nanorings as a function of the unit cell number （P）, the channel number （M =N2）, surface disorder （ζ）, and temperature （T） is theoretically investigated in terms of rotational symmetry. On the whole, the typical current increases linearly with √M but decreases exponentially with P, while wide fluctuations exist therein. In the presence of surface disorder, the persistent current decreases with ζ in the regime of weak disorder but increases in the regime of strong disorder. In addition, it is found that the persistent current in perfect rings decreases exponentially with temperature even at T 〈 T＊, while in most disorder rings, the typical current decreases slightly with temperature at T 〈 T＊.
基金supported by the National Natural Science Foundation of China(22108024)the Liaoning Provincial Department of Education University Basic Research Project(LJ212410152028)+1 种基金the Dalian High-level Talent Innovation Support Program of China(2022RQ016)the Fundamental Research Fundamental Funds for the Central Universities(DUT22LAB601).
文摘Photodynamic therapy(PDT)and photothermal therapy(PTT)synergistic treatment for hypoxic tumors,always requires highintensity light irradiation.This study introduces an intramolecular modulation approach for achieving PDT and PTT synergy under gentle light irradiation via the formation of tightly packed J-aggregated nanorings.Specifically,cyanine dyes,designated as TYA and TYB,were synthesized and compared to investigate the influence of intramolecular and intermolecular forces on the formation of compact J-aggregates.Compared to TYA(14.22°,8.58Å),the planar quinoline moieties in TYB exhibit a more pronounced rotation around the methylene linker(50.21°),which facilitates intermolecular slippage and reduces the stacking distance to 4.91Åin J-aggregated nanorings(TYB J-NPs).The smaller monomer separations facilitate the generation of photothermal effects under mild light irradiation.These TYB J-NPs generate reactive oxygen species(ROS)levels comparable to those produced by TYA J-aggregates,while simultaneously producing a thermal effect under near-infrared(NIR)light irradiation(35 mW/cm^(2),10 min,ΔT>20℃).This dual functionality synergistically enables in vivo fluorescence and photothermal imaging,and effectively inhibits the growth and invasion of 4T1 tumors in mice.Moreover,TYB J-NPs demonstrate substantial antibacterial efficacy against both Gram-positive and Gram-negative bacteria,thereby offering effective antibacterial protection during tumor phototherapy.In summary,the intramolecular twisting of TYB effectively resolves the bottleneck associated with intermolecular repulsions at large molecular separations,thereby facilitating the formation of densely packed J-aggregates.This represents the first instance where J-aggregated nanorings enable concurrent PDT and PTT with antibacterial effectiveness under low-density NIR light irradiation.This work may significantly enhance the therapeutic potential of cyanine dyes in cancer treatment,pathogenic bacterial infections,and other diseases.
基金funding from the National Science Foundation of China(22225108,223B2120,22201064,and 22471060).
文摘CONSPECTUS:Topologically unique nanocarbon materials with optoelectronic potential are both fascinating and challenging synthetic targets.Their distinctive molecular topologies often lead to chirality,unique optoelectronic properties,and encapsulation capabilities,stimulating advances in synthetic chemistry and materials science.The research on curved nanocarbon materials has garnered substantial interest due to the intricate relationship between theirπ-conjugation and molecular geometry,as well as their emerging applications in various fields.The introduction of curvature significantly affects the redox behaviors,optical properties,charge-transport capabilities,and self-assembly processes of these nanocarbon materials.The representative examples of curved aromatic systems are cycloparaphenylenes(CPPs)and related carbon nanorings.In these molecules,the nonplanar aromatic structures can induce unique radialπ-conjugation and further endow them with distinctive photophysical properties.By adjusting the number of benzene rings in a CPP or incorporating diverse polycyclic aromatic hydrocarbon units,researchers can finely tune the optical and electronic properties of these nanostructures.Many potential applications can be discovered in the fields of fluorescent probes,organic light-emitting diodes(OLEDs),and optoelectronic devices.These properties establish CPP as an important scaffold to create novel carbon nanostructures.With the ongoing advancements in molecular topology,new opportunities are emerging within the fields of materials science,molecular electronics,and biomedicine.Given the exceptional electronic and photophysical properties of CPPs,there has been considerable interest in the development of topologically intriguing bis/multimacrocyclic architectures.It is anticipated that high dimensionality and unexplored topologies will endow these bis/multimacrocycles with unparalleled physical and chemical properties.This concise Account highlights recent developments from our research group on topologically functional materials based on CPP carbon nanorings,particularly their potential applications.Our discussion focuses on(i)the design and synthesis of a series of fully sp2-hybridized all-benzenoid bismacrocycles,as well as[n]cycloparaphenylene-pillar[5]arene bismacrocycles;(ii)the construction of all-CPP-based longπ-extended polymeric segments of the armchair SWCNT;and(iii)the synthesis of CPP-based mechanically interlocked molecules,specifically[12]CPP-[3]catenane.Structures like these CPP-based bis/multimacrocyclic architectures exhibit distinct properties-including radialπ-conjugation,supramolecular properties,chirality,and unexpected dualemissive and anti-Kasha photophysical characteristics due to their nonplanar geometries-that allow precise tuning of their HOMO−LUMO gap,emission profiles,and charge-transport behaviors.These properties make them promising for applications in OLEDs,circularly polarized luminescence(CPL)materials,lithium-ion batteries(LIBs),and photoelectroactive devices.By discussing recent work,we demonstrate the potential of these carbon nanorings for future technologies in optoelectronics,chiroptics,and nanotechnology.We also discuss challenges and future directions,emphasizing the importance of precise control over the size,shape,and conjugation of these topological structures to broaden their applications in molecular machines,sensors,and functional materials.
基金This work was supported by the National Basic Research Program of China （No. 2013CB932602）, the Program of Introducing Talents of Discipline to Universities （No. B14003）, National Natural Science Foundation of China （No. 51527802, 51372020 and 51232001）, Beijing Municipal Science ＆ Technology Commission, Beijing Higher Education Young Elite Teacher Project （No. YETP0354）, Program for New Century Excellent Talents in University （No. NCET- 12-0777）.
文摘We report the preparation of nanocomposites of reduced graphene oxide with embedded Fe3O4/Fe nanorings （FeNR@rGO） by chemical hydrothermal growth. We illustrate the use of these nanocomposites as novel electromagnetic wave absorbing materials. The electromagnetic wave absorption properties of the nanocomposites with different compositions were investigated. The preparation procedure and nanocomposite composition were optimized to achieve the best electromagnetic wave absorption properties. Nanocomposites with a GO：cx-Fe203 mass ratio of 1：1 prepared by annealing in HdAr for 3 h exhibited the best properties. This nanocomposite sample （thickness = 4.0 mm） showed a minimum reflectivity of -23.09 dB at 9.16 GHz. The band range was 7.4-11.3 GHz when the reflectivity was less than -10 dB and the spectrum width was up to 3.9 GHz. These figures of merit are typically of the same order of magnitude when compared to the values shown by traditional ferric oxide materials. However, FeNR@rGO can be readily applied as a microwave absorbing material because the production method we propose is highly compatible with mass production standards.
基金This work was financially supported by the National Key R&D Program of China(Nos.2017YFA0208200 and 2016YFA0204100)the National Natural Science Foundation of China(Nos.22025108 and 51802206)+2 种基金Guangdong Provincial Natural Science Fund for Distinguished Young Scholars(No.2021B1515020081)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)and the start-up supports from Xiamen University and the Guangzhou Key Laboratory of Low Dimensional Materials and Energy Storage Devices(No.20195010002).
文摘The design of highly active and stable RuO_(2)-based nanostructures for acidic oxygen evolution reaction(OER)is extremely important for the development of water electrolysis technology,yet remains great challenges.We here demonstrate that the incorporation of S into RuCuO nanorings(NRs)can significantly enhance the acidic OER performance.Experimental investigations show that the incorporation of S can optimize the interaction of Ru and O,and therefore significantly suppresses the dissolution of Ru in acidic condition.The optimized catalyst(SH-RuCuO NRs)displays superior OER performance to the commercial RuO_(2)/C.Impressively,the SH-RuCuO NRs can exhibit significantly enhanced stability for 3,000 cycles of cyclic voltammetry test and more than 250 h chronopotentiometry test at 10 mA·cm^(-2)in 0.5 M H_(2)SO_(4).This work highlights a potential strategy for designing active and stable RuO_(2)-based electrocatalysts for acidic OER.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （No. 21474037） and Doctoral Fund of Ministry of Education of China （No. 20130061110019）.
文摘In this paper, we report a new strategy for the fabrication of gold nanoring arrays via colloidal lithography and polymer-assisted self-assembly of gold nanoparticles （Au NPs）. First, multi-segmented polymer nanorod arrays were fabricated via colloidal lithography. They were then used as templates for Au NP adsorption, which resulted in nanoparticles on the poly（4-vinyl pyridine） （P4VP） segments. Continuous gold nanorings were formed after electroless deposition of gold. The diameter, quantity, and spacing of the gold nanorings could be tuned. Three dimensional coaxial gold nanorings with varying diameters could be fabricated on a polymer nanorod by modifying the etch parameters. The nanorings exhibited optical plasmonic resonances at theoretically predicted wavelengths. In addition, the polymer-assisted gold nanorings were released from the substrate to generate a high yield of flee-standing nanorings. This simple, versatile method was also used to prepare nanorings from other metals such as palladium.
基金This work was supported by the National Natural Science Foundation of China(Nos.21774043,21975098,and51905526)the Fundamental Research Funds for the Central Universities(JLU)and the Program for JLU Science and Technology Innovation Research Team(No.2017TD-06)Jiaxing Science and Technology Project(No.2020AY10018).
文摘Gold nanoring arrays are widely applied in various fields benefitting from their localized surface plasmon resonance(LSPR)properties.A key advantage of gold nanoring arrays is that the dipole resonance peak can be systematically tuned by changing the dimensions of gold nanoring arrays.However,most of the currently reported methods for preparing gold nanoring arrays cannot conveniently control the heights of the nanorings at a low cost.Here we introduce a facile method for preparing gold nanoring arrays with tunable plasmonic resonances using colloidal lithography.The dimensions of the nanorings including diameters,lattice constants,even the heights of the nanorings can be conveniently varied.Fourier transform near-infrared(FT-NIR)absorption spectroscopy was used to obtain the plasmonic resonance spectra of the nanoring arrays.All the prepared gold nanoring arrays exhibited a strong NIR or infrared(IR)plasmonic resonance which can be tuned by varying the nanoring dimensions.This versatile method can also be used to fabricate other types of plasmonic nanostructures,such as gold nanocone arrays.The obtained gold nanoring arrays as well as nanocone arrays may have potential applications in surface-enhanced spectroscopy or plasmonic sensing.
基金Support from the National Natural Science Foundation of China(grants No.21906001 and No.51721006)China Postdoctoral Science Foundation(grant No.2019M650007)is acknowledgedsupported by the Beijing Nova Program(Z19111000110000).
文摘Radioactive wastewater containing high concentration of radionuclides poses severe threats to ecosystem and human health,so efficient removal of these toxic heavy metals is urgently needed.Titanate nanomaterials have been demonstrated good adsorbents for heavy metals due to ion exchange property.In this study,titanate nanorings(TNRs)were synthesized using the facile hydrothermal-cooling method.The TNRs were composed of sodium trititanate,with a chemical formula of Na_(0.66)H_(1.34)-Ti_(3)O_(7)·0.27H_(2)O and a Na content of 2.38 mmol/g.The TNRs demonstrated sufficient adsorption performance to radionuclides europium(Eu)and uranium(U)ions.Specifically,even at a high initial concentration of 50 mg/L,86.5% and 92.6% of the two metal ions can be rapidly adsorbed by the TNRs within 5 min,and equilibrium was reached within 60 min at pH 5.The maximum adsorption capacity(Qmax)obtained by the Langmuir isotherm model was 115.3 mg/g for Eu(Ⅲ)and 282.5 mg/g for uranium U(Ⅵ)at pH 5,respectively.The adsorption capacities of the two metals under various water chemical conditions were highly related to their species.Ion exchange between metal cations and Na^(+) in the TNR interlayers was the dominant adsorption mechanism,and adsorption of U(Ⅵ)was more complicated because of the co-existence of various uranyl(UO_(2)^(2+))and uranyl-hydroxyl species.The spent TNRs were effectively regenerated through an acid-base or ethylenediamine tetraacetic acid(EDTA)treatment and reused.Considering the large adsorption capacity and quick kinetic,TNRs are promising materials to remove radionuclides in environmental purification applications,especially emergent treatment of leaked radionuclides.
基金supported by the National Natural Science Foundation of China(Nos.51974370 and 51874360)the Program of Huxiang Young Talents(No.2019RS2002)+1 种基金the Innovation and Entrepreneurship Project of Hunan Province,China(No.2018GK5026)the Fundamental Research Funds for the Central Universities of Central South University(No.2019zzts225).
文摘Porous graphitic carbon nanorings(PGCNs)are proposed by smart catalytic graphitization of nano-sized graphene quantum dots(GQDs).The as-prepared PGCNs show unique ring-like morphology with diameter around 10 nm,and demonstrate extraordinary mesoporous structure,controllable graphitization degree and highly defective nature.The mechanism from GQDs to PGCNs is proven to be a dissolution-precipitation process,undergoing the procedure of amorphous carbon,intermediate phase,graphitic carbon nanorings and graphitic carbon nanosheets.Further,the relationship between particles size of GQDs precursor and graphitization degree of PGCNs products is revealed.The unique microstructure implies PGCNs a broad prospect for energy storage application.When applied as negative electrode materials in dual-carbon lithium-ion capacitors,high energy density(77.6 Wh·kg^(−1))and super long lifespan(89.5%retention after 40,000 cycles at 5.0 A·g^(−1))are obtained.The energy density still maintains at 24.5 Wh·kg^(−1)even at the power density of 14.1 kW·kg^(−1),demonstrating excellent rate capability.The distinct microstructure of PGCNs together with the strategy for catalytic conversion from nanocarbon precursors to carbon nanorings opens a new window for carbon materials in electrochemical energy storage.
基金This work was supported by the National Natural Science Foundation of China[12025201,11521202,11890681,11522214].
文摘As an ideal high-density storage unit,magnetic nanorings have become a research hotspot in recent years.We can both study the evolution of microscopic state of magnetization and acquire macroscopic magnetic properties by micromagnetic simulation,which has thus been widely used.However,traditional micromagnetism cannot simulate complex stress state.Due to the introduction of microelasticity theory,the phase field method for magnetic materials can be used to calculate the coupling effect of stress and magnetic field.However,the computing model usually needs to satisfy periodic boundary condition.In this paper,the phase field simulation combined with the finite element method is employed.By using user defined element,the evolution of magnetic domain structures of the double-hole nanorings has been studied.In different diameter of the holes and external magnetic field direction,we have found seven kinds of magnetic domain evolution mechanism.Among them,the twin-vortex evolution mechanism with high stability and low demagnetization interference characteristics of advantages,has good application prospect in magnetic random-access memory(MRAM)unit.
