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As a semiconductor material with a 2D-laminate structure, g-C3N4 (bandwidth 2.7 eV) has a similar structure and excellent performance to graphene. However, high surface energy and photogenerated e–h recombination of g-C3N4 seriously hinder its application in the field of marine anticorrosion and antifouling. To solve these problems, we synthesized the g-C3N4 nanosheets decorated with ZnO nanoring via chemical etching technology. Whether the NR ZnO-CNNs have surface protection performance among the pure EP on the corrosion protection for metal substrate were investigated. The antifouling properties NR ZnO-CNNs 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 ZnO-CNNs/EP within 45 days showed two orders of magnitude higher than that of pure EP in the 3.5 wt% NaCl solution. Besides, Local electrochemical impedance spectroscopy (LEIS) further explored the anticorrosion behavior of NR ZnO-CNNs/EP coating, which indicated that the NR ZnO-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 ZnO-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/mL of NR ZnO-CNNs hybrid could make chlorella sharply reduce within 4 days. Simultaneously, the corrosion protection and photocatalytic antifouling mechanisms of NR ZnO-CNNs were proposed, thus it provided a broader platform for the design of versatile marine protection materials.

Herein, we report the synthesis and properties of a [6,6] hollow bilayer cylindrical nanoring (HBCNR) from a planar macrocycle via a Diels-Alder and Yamamoto coupling reaction. The fluorescence quantum yield of HBCNR was determined to be ΦF = 52%, which is four times higher than its precursor. In addition, its hollow nanoring configuration was also simulated by theoretical studies, and the tension energy was estimated to be 47.1 kcal/mol.

In this work, different structures are designed based on graphene square-nanoring resonator (GSNR) and simulated by the three-dimensional finite-difference time-domain (3D-FDTD) method. Depending on the location and number of graphene nanoribbons (GNR), the proposed structures can be utilized as a band-pass filter, wavelength demultiplexer, or power splitter in the mid-infrared (MIR) wavelengths. The tunability of the suggested assemblies is easily controlled by changing the dimensions and/or the chemical potential of the GSNRs. Benefiting from the nanoscale and ultra-compact GNRs, these structures can be proposed as basic blocks for optical computing and signal processing in the MIR region.

Hierarchical Ag/SiO2/TiO2 nanobowl (NB) arrays were fabricated for use as plasmonic photoanodes for solar-hydrogen conversion. The nanobowls had large pore size and were composed of an upper TiO2 nanoring and a lower TiO2 nanohole. A thin SiO2 inter-layer was introduced as an electron transmission channel to change the mechanism of hot electron transport. Simulations were performed to characterize the variation of electron concentration in Ag/SiO2/TiO2 NB arrays, taking into account both the optical transition of photogenerated electrons, and electron tunneling. The multiphysics coupling function of COMSOL software provided the light source for optical transition of photogenerated electrons, and a Wentzel-Kramers-Brillouin model was employed to represent the tunneling. The results demonstrate that the TiO2 nanoring was a transporter, which transmitted electrons downward to the nanohole. The SiO2 layer replaces the Schottky barrier to become a bridge for tunneling of hot electrons in high- and low-energy states into TiO2. Moreover, the coverage of the SiO2 layer helped increase the light absorption of TiO2, it also reduced the near electric field coupling between Ag and TiO2. Accordingly, under AM 1.5 light irradiation, the photocurrent density and average hydrogen evolution rate of Ag/SiO2/TiO2 were 1.8 and 2.2 times higher, respectively, than those of pure TiO2, implying far more efficient migration of carriers.

In this work, the thermoelastic dissipation (TED) for circular-cross-sectional micro/nanoring model is studied including the single-phase-lag (SPL) time based on the non-Fourier heat conduction model. The toroidal solid ring is simple to manufacture and thus the potential is high for future development. Also, the present model is more precise than the 1D or 2D beam or rectangular-cross-sectional ring because the governing equation is established by 3D coordinate system. Moreover, the SPL shows the delay time of heat-flux and is especially important in cryogenic or ultrafast-vibration environments. In this regard, characteristics of the TED is mainly analyzed according to the lagging time, geometrical shape, mode number and temperature, etc. Using the experimental data in literatures, the effectiveness of this work is verified to represent the investigations. The spectra of the TED with the phenomenon of multiple peaks are presented, and then the results can be grouped and compared with previous works. Moreover, the temperature distribution is graphically described to explain the SPL mechanism.

In this paper, by defining a new physical quantity called as the frequency offset in the harmonic oscillator model and combining with the established plasmon coupling model, we successfully explain the anti-crossing property caused by plasmon coupling of dimer composed of a silver nanoring and a silver nanorod. In the plasmon coupling model, we reasonably reveal that the physical mechanism of the coupling between bright mode and dark mode of the plasmons is mainly represented by the coulomb potential and the electrostatic potential. With this model, we explain also the asymmetric feature the variation of frequency offset and coupling coefficient with coupling distance.

In the present study, a modified solvothermal reaction of (hematite) with titanium(IV) butoxide and gold(III) chloride produced ternary Au@TiO2/α-Fe2O3 nanocomposite. The designed Au@TiO2/α-Fe2O3 photocatalyst exhibits nanoring-like structure with high crystallinity indicating the possibility of manufacturing extreme structures and offering a new nanostructure that was not previously studied. Both TiO2 and Au nanoparticles (NPs) were found to be dispersed uniformly on the α-Fe2O3 surface. X-ray diffraction powder technique combined with X-ray photoelectron (XPS) and Raman spectroscopy confirm the formation of the three materials with cubic Au, anatase TiO2 and hematite α-Fe2O3 structures, respectively. The photocatalytic activity proves the performance of this ternary heterojunction to decomposes different pollutants. It was found that, TiO2 absorbs UV-light, α-Fe2O3 absorbs both UV and Visible light and plasmonic gold NPs work as an electron mediator and therefore exhalt the photocatalytic efficiency of the ternary Au@TiO2/α-Fe2O3 photocatalyst. The present work delivers a novel perception to develop a stable photocatalyst based metal oxide/noble-metal hetero-nanostructure for the degradation of different types of pollutants in the industrial zones.

Thermoelastic damping (TED) is one of the significant factor to design the high-efficiency sensors or resonators. Up to now, the single-phase-lagging (SPL) has been analyzed for the various TED mod...

The first example of a neutral spin‐delocalized carbon‐nanoring radical was achieved by integration of the open‐shell phenalenyl unit into cycloparaphenylene (CPP). Spin distribution in this hydrocarbon is localized primarily on the phenalenyl segment and partially on the CPP segment as a consequence of steric and electronic effects. The resulting geometry is reminiscent of a diamond ring, with pseudo‐perpendicular arrangement of the radial and the planar π‐surface. The phenylene rings attached directly to the phenalenyl unit give rise to a steric effect that governs a highly selective dimerization pathway, yielding a giant double nanohoop. Its π‐framework made of 158 sp2‐carbon atoms was elucidated by single‐crystal X‐ray diffraction, which revealed a three‐segment CPP‐peropyrene‐CPP structure. This nanocarbon shows a fluorescence profile characteristic of peropyrene, regardless of which segment gets excited. These results in conjunction with DFT suggest that adjusting the size of the CPP segments in this double nanohoop could deliver donor–acceptor systems., A neutral open‐shell carbon nanoring was achieved by integration of the phenalenyl unit into the cycloparaphenylene framework. It is shown that the spin distribution and reactivity of this hydrocarbon in the shape of a diamond ring are a result of steric and electronic effects and that selective dimerization yields a double nanohoop with a radial‐planar‐radial arrangement of its three π‐conjugated segments comprising a total of 158 sp2‐carbon atoms.

The past few years witnessed the rapid development of bottom-up synthesis strategies for preparing various nanostructures (i.e., nanoparticles, nanorods, nanowires, etc.) with distinct morphology-dependent properties. In this study, we reported a facile and efficient synthesis method for preparing anatase titanium dioxide (TiO2) nanorings based on multiarm, starlike amphiphilic polystyrene-b-poly(acrylic acid) (PS-b-PAA) diblock copolymers as nanoreactors which were prepared via a sequential atom-transfer radical polymerization (ATRP) technique followed by the conversion of polystyrene-b-poly(tert-butyl acrylate) (PS-b-PtBA) to PS-b-PAA. The outer PAA block of nanoreactors possessed carboxylic acid groups which could coordinate with a titanium precursor followed by high-temperature calcination to form crystalline TiO2 nanorings. The living nature of ATRP enabled the precise preparation of starlike diblock copolymer nanoreactors with a controlled length of each block (i.e., PtBA and PS), thereby tailoring the inner diameter and wall thickness of the resulting TiO2 nanorings, which were inaccessible to conventional routes.

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.

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.

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.

Preparing the low-cost nanomaterials for electrocatalytic processes is still a big challenge. Mesoporous cobalt hydroxide and cobalt oxide nanoparticles were prepared through simple soft chemistry as high-performance materials for durable electrocatalyst for OER and supercapacitive applications. The synthesis method is used to prepare nanoring particles in neither emulsion nor template-directed method. The final nanoparticles display mesoporous hexagonal nanoring morphology. The physio-chemical properties of the as-synthesized nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen adsorption-desorption techniques. The TEM characterizations prove that NPs retain the topotactical relationship in their structure during the conversion process. The BET measurements prove the mesoporous nature of the nanorings, having good specific surface area and pore volume. Finally, the electrochemical performance toward water splitting and supercapacitor applications were investigated by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and cyclic voltammetry (CV) techniques. The Co3O4 NPs exhibits better catalytic properties than Co(OH)2 NPs when applied as electrocatalyst in an alkaline medium for water splitting and supercapacitor measurements. The enhanced electrocatalytic performance attributed to the mesoporous structure along with high pore volume, which provides more active boundary sites for the electrochemical process, resulted in the enhanced exchange of the intermediates and more efficient electron transfer. This synthetic methodology, with the advantages of inexpensive/non-complicated experimental setup and high electrochemical performance, could shed light on the development of non-expensive electrocatalysts for clean energy production and storage.

One 18-metal Eu(III) nanoring (size: 1.0 × 2.7 × 2.7 nm) was constructed as a rapid ratiometric fluorescent probe for the detection of dipicolinic acid with high sensitivity and selectivity, by using two types of polydentate organic ligands.

Direct π-extension by the Scholl reaction for solution-based growth of armchair edges in curved macrocyclic hydrocarbon nanostructures is a great challenge. To date, several attempts at direct π-extension of small highly strained macrocycles have failed. Herein, we report a fixed two-bond approach for direct functionalization of small strained macrocyclic nanorings. The reaction occurs selectively to produce large π-extended molecular crowns with high yields. The design of these precursors features two peripheral C–C bonds that are readily incorporated into the extended aromatic moiety to overcome strain-induced side reactions, such as 1,2-phenyl shift. The crown-shaped macrocycle 10 showed a significant redshift (∼100 nm for absorption) compared with its precursor. This synthesis strategy could pave the way towards the π-extension of strained conjugated macrocycles and their potential applications in electron-transport devices.

We report a novel strategy for the synthesis of Pt@Au nanorings possessing near-field focusing capabilities at the center through which single-particle surface enhanced Raman scattering could be readily observed. We utilized Pt@Au nanorings as a light-absorber; the absorbed light could be focused at the center with the aid of a Au nanoporous structure. We synthesized the Au nanolens structure through a Galvanic exchange process between Au ions and Ag block at the inner domain of the Pt@Au nanoring. For this step, Ag was selectively pre-deposited at the inner domain of the Pt@Au nanorings through electrochemical potential-tuned growth control and different surface energies with regard to the inner and outer boundaries of the nanoring. Then, the central nanoporous architecture was fabricated through the Galvanic exchange of sacrificial Ag with Au ions leading to the resulting Au nanoring with a Au nanoporous structure at the center. We monitored the shape-transformation by observing their corresponding localized surface plasmon resonance (LSPR) profiles. By varying the rim thickness of the starting Pt@Au nanorings, the inner diameter of the nanolens was accordingly tuned to maximize near-field focusing, which enabled us to obtain the reproducible and light-polarization independent measurements of single-particle SERS. Through theoretical simulation, the near-field electromagnetic field focusing capability was visualized and confirmed through single-particle SERS measurement showing an enhancement factor of 1.9 × 108 to 1.0 × 109., We synthesized a Au nanolens with electromagnetic near-field focusing capability by integrating a Au nanoporous structure at the center of the Pt@Au nanoring via synthetic steps of eccentric growth of Ag and nanoscale Galvanic exchange reaction.

An 18-metal lanthanide nanoring [Yb18(L1)8(HL2)2(OAc)20(MeOH)8(EtOH)6(H2O)4] (1), which shows a ratiometric fluorescent response to DPA, was constructed through the strategy of using two types of polydentate organic ligands. The addition of DPA increases the visible ligand-centered emission, but decreases the NIR lanthanide luminescence of 1. The limit of luminescent detection of 1 for DPA is 1.5 μM. The high fluorescence sensitivity of 1 to DPA is not affected by the existence of interferents such as aromatic carboxylates and ions.

The melamine·barbiturate H-bonded rosette motif is of comparable dimensions and symmetry to the cavity of a butadiyne-linked 6-porphyrin nanoring. Functionalisation of each of the barbiturate components and the pyrimidine components of a H-bonded rosette with a pyridine ligand leads to a self-assembled hexapyridine ligand, which binds cooperatively to the zinc porphyrin nanoring. UV-vis-NIR and 1H NMR experiments show that the 7-component assembly forms at concentrations at which neither the H-bonding interactions nor the zinc porphyrin–pyridine interactions are formed in the absence of one of the three components. The mean effective molarities of these rosette complexes are around 200 mM in chloroform at 298 K., Mixing barbiturates and pyrimidines equipped with pyridine ligands to leads to self-assembly of a hexadentate rosette ligand, which is complementary to a hexameric zinc porphyrin macrocycle.

Present herein is the first example of aluminium nanoring assembly by fatty acids. And the auxiliary alcohol sites can be modified either by monohydric alcohols (AlOC-33 to AlOC-35) or diols (AlOC-36 to AlOC-38). The monohydric alcohol modified ten-membered aluminium (Al10) rings are coplanar, while the diol modified ones possess a saddle-shaped configuration. Interestingly, the diol modified Al10 ring (AlOC-36) can convert into a coplanar ring (AlOC-33-B). AlOC-33-B possesses a similar molecular structure but a different supramolecular structure with AlOC-33. The structural transformation is confirmed to be a thermodynamically spontaneous process through density-functional theory (DFT) calculations.

One 18-metal Nd(III) nanoring, [Nd18(L1)8(HL2)2(OAc)20(MeOH)8(EtOH)6(H2O)4]·2(MeOH)·6(H2O) (1), was constructed by the use of a hexadentate Schiff base ligand. For 1, the near-infrared (NIR) luminescence of Nd(III) was detected under the excitation of absorption band at 371 nm. The study of luminescent sensing properties exhibits that, even with the existence of other antibiotics, this Nd(III) nanoring displays high sensitivity and selectivity to nitrofuran antibiotics (NFAs). The luminescence quenching constants and limits of detection of 1 to NFAs are found to be 1.4 × 104 to 3.5 × 104 M-1 and 0.9-2.2 μM, respectively.

Given the special place of hybrid logic circuits such as all-optical full adders in next-generation digital systems, a new kind of these structures using two-dimensional (2D) photonic crystals (2D-PC) is designed and simulated herein. The proposed structure is made of a hexagonal nanoring resonator (NRR), a coupling rod, and several waveguides. In this all-optical full adder, the mechanism of the interference effect in the PCs is used to simplify and minimize the structure. To make the structure flexible, the radius of the dielectric rod in the whole structure and the NRR are considered based on a lattice constant of 0.2a and 0.04a, respectively. The structure is operated at a wavelength of 1550 nm, considering the value of the power entering the waveguides and that exiting the Carry and Sum ports. To analyze the all-optical full adder, the plane-wave expansion method and finite-difference time-domain method are applied respectively to calculate the bandgap diagram and obtain the transmission and propagation of the optical field. In the proposed structure, the contrast ratio at the Carry and is been investigated in a unique and novel way, yielding values of 10.68 and 9.03 dB, respectively. In addition, the maximum and minimum response time for the Carry and Sum are obtained as 1.6 and 0.75 ps, respectively. The total footprint of the structure is about 183 µm2. Due to its ultracompact size, low power consumption, fast response time, and simple structure, this all-optical full adder is suitable for use in low-power optical integrated circuits.

Illumination of colloid sphere monolayers by circularly polarized beams enables the fabrication of concave patterns consisting of circular nanohole miniarrays that can be transferred into convex metal nanoparticle patterns via a lift-off procedure. Unique spectral and near-field properties are achievable by tuning the geometry of the central nanoring and quadrumer of slightly rotated satellite nanocrescents and by selecting those azimuthal orientations that promote localized plasmon resonances. The spectral and near-field effects of hexagonal patterns made of uniform gold nanorings and nanocrescents, that can be prepared by transferring masks fabricated by a perpendicularly and obliquely incident single homogeneous circularly polarized beam, were studied to uncover the supported localized plasmonic modes. Artificial rectangular patterns made of a singlet nanoring and singlet nanocrescent as well as quadrumer of four nanocrescents were investigated to analyze the role of nano-object interactions and lattice type. It was proven that all nanophotonical phenomena are governed by the azimuthal orientation independent localized resonance on the nanorings and by the C2, C1 and U resonances on the nanocrescents in case of $\bar{E}$-field oscillation direction perpendicular and parallel to their symmetry axes. The interaction between localized surface plasmon resonances on individual nano-objects is weak, whereas scattered photonic modes have a perturbative role at the Rayleigh anomaly only on the larger periodic rectangular pattern of miniarrays. Considerable fluorescence enhancement of dipolar emitters is achievable at spectral locations promoting the C and U resonances on the composing nano-objects., arXiv admin note: substantial text overlap with arXiv:2005.07616

In this work, a novel reduction-responsive disulfide bond-containing cycloparaphenylene nanoring molecule (DSCPP) with a pyriform shape has been designed. In addition, the interactions between the designed nanoring (host) and fullerenes C60 and C70 (guests) were investigated theoretically at the M06-2X/6-31G(d,p) and M06-L/MIDI! levels of theory. By analyzing geometric characteristics and host–guest binding energies, it is revealed that the designed DSCPP is an ideal host molecule of guests C60 and C70. DSCPP presents excellent elastic deformation during the encapsulation of C60 and C70. The high binding energies suggest that both DSCPP⊃C60 and DSCPP⊃C70 (∼92 and 118 kJ·mol–1 at the M06-2X/6-31G(d,p) level of theory) are stable host–guest complexes, and the guest C70 is more strongly encapsulated than C60 in the gas phase. The thermodynamic information indicates that the formation of the two host–guest complexes is thermodynamically spontaneous. In addition, the frontier molecular orbital (FMO) features and intermolecular weak interaction region between DSCPP and fullerenes gusts are discussed to further understand the structures and properties of the DSCPP⊃fullerene systems. Finally, the ring-opening mechanism of the DSCPP under reduction conditions is investigated.

Breaking the morphological and compositional symmetries of metallic nanoparticle (NP) dimers provides a novel approach to modulate plasmon coupling between the NPs. In this study, we theoretically investigate the effect of symmetry breaking on the plasmonic coupling in morphologically asymmetric Au nanoring-nanodisk (NR-ND) dimer, compositionally heterogeneous Au-Ag nanoring dimer, and compositionally as well as morphologically asymmetric Au-Ag NR-ND heterodimers. It has been found that when the inner radii of symmetrical Au NR dimer is decreased, the scattering spectral intensity of coupled bonding mode and higher-order coupled bonding mode drastically decreases and increases, respectively. Besides, the effect of aspect ratio on the plasmon resonance modes is investigated. Furthermore, with fixed geometric parameters of one NR and by morphing the shape of the other NR into ND through inner radius, we show the generation and modification of a Fano resonance. As a result of introducing morphological and compositional asymmetry separately, single Fano-type spectral feature is observed in the scattering spectra. We demonstrate that the double Fano resonances can be easily achieved in compositionally and morphologically asymmetric heterodimer with double symmetry breaking. These dual modes are caused by the interference of dipolar bright mode (localized LSPR modes) of Ag NP with the quadrupole and hexapole modes (interband transitions) of the Au NP. Finally, at optimum asymmetric heterodimers, we discussed the effect of refractive index on the Fano-type resonance. These new and simple designs provide a novel insight to modulate optical response and the generation of higher-order Fano resonances, which have many potential applications such as in photonics and refractive index sensing.

The volatile organic compound, nitrobenzene (NB) is made to interact with the primary material, Red-Tricycle-Arsenene (red-T-As) nanoring at four global minima sites (bridge, hollow, valley and ring-sites) by employing density functional theory method. The structural sturdiness of the primary material is evidenced with the cohesive conformation energy of – 3.462 eV/atom. Furthermore, the electronic fingerprints of the pristine and NB surface-assimilated red-T-As nanoring like the energy-gap based Band-Structure and Projected Density of States (PDOS) spectrum along with electron difference density are reckoned. In addition, the adsorption features of NB on red-T-As nanoring, namely, the Bader charge transfer, binding energy, and average energy gap variation are determined. The ciphered attributes articulate the utility of red-tricycle-arsenene nanoring as an efficient chemi-resistor to detect nitrobenzene.

Shape complementarity is of paramount importance in molecular recognition, but has rarely been adopted in the self-assembly of colloidal particles, especially in the case of nanoparticles of different shapes. Here, we demonstrated a simple, yet powerful strategy for fabricating gold nanoring-based heterogeneous nanostructures (AuNR-HNs) with well-defined geometries and high yield. The assembly of various geometries of AuNR-HNs is modulated by the shape complementarity of plasmonic nanorings and nanospheres. We also present experimental evidence of dark quadrupolar ring mode excitation in AuNR-HNs through single-particle optical measurements. Our strategy will be beneficial in the study of nanoparticle assembly, photonic element interaction, and the development of plasmon-based optical devices.

The supramolecular complexes of metallofullerenes and carbon nanoring were constructed and their properties were studied. The size-selective encapsulation of metallofullerene Sc3N@C78, Sc3N@C80 and Sc2C2@C82 by a carbon nanoring of [12]Cycloparaphenylene ([12]CPP) was found. Fluorescence spectral titration experiments showed the different quenching effect of matallofullerenes on photoluminance of [12]CPP. It was found that Sc2C2@C82 has a stronger affinity to [12]CPP, and their supramolecular complex has a stronger host-guest interaction. Electrochemical results revealed that the redox potentials of encapsulated matallofullerenes are shifted compared to pristine species. Moreover, these supramolecular complexes can be dissociated using a metal-organic framework (MOF-177), which can only absorb the metallofullerene, leaving behind hollow [12]CPP. These results reveal the special supramolecular chemistry for metallofullerenes, [12]CPP nanoring, and porous MOF-177. In addition, the powerful attraction of porous MOF-177 for metallofullerene can break the host-guest interaction between metallofullerene and nanoring, which is applicable in separation.

International audience; For the last ten years, ring-shaped -conjugated macrocycles possessing radially directed -orbitals have been subject to intense research. The electronic properties of these rings are deeply dependent on their size. However, most studies involve the flagship family of nanorings: the cyclo-para-phenylenes. We report herein the synthesis and study of the first examples of cyclofluorenes possessing five constituting fluorene units. The structural, optical and electrochemical properties were elucidated by X-ray crystallography, UV-vis absorption and fluorescence spectroscopy, and cyclic voltammetry. By comparison with a shorter analogue, [4]-cyclofluorene, we show how the electronic properties of [5]-cyclofluorenes are drastically different from those of [4]-cyclofluorenes, highlighting the key role played by the ring size in the cyclofluorene family.

Ferromagnetic Fe nanowires surrounded by two plasmonic Au nanorings (FeAuNRsNWs) were synthesized by coaxial lithography (COAL). They were characterized under irradiation (three different wavelengt...

The electronic structure and structural and optoelectronic properties of hexathiopentacene (HTP) nanorings have been carried out by density functional theory (DFT) and time-dependent DFT (TD-DFT). Herein, the binding energy per atom, ionization potential, electron affinity, chemical hardness, highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap, refractive index, charge distributions, absorbance spectra and non-linear optical properties have been measured. The calculations on these nanorings show that the HOMO–LUMO gaps range from 1.87 eV to 1.28 eV, which corresponds to the bandgap of known photovoltaic semiconductors, while the absorbance spectrum increases from 674 nm (1.84 eV) to 874 nm (1.42 eV), which indicates that the HTP nanorings absorb more light as the nanoring size is increased. From the binding energy, the stability of the HTP nanorings is higher than that of the HTP structure. Our results show that an increase in the size may play a significant role in improving the design of optoelectronic devices based upon these HTP nanorings. © 2020, The Minerals, Metals & Materials Society.

Hydrogen can be produced by photoelectrochemical (PEC) water splitting using a KOH solution as an electrolyte and TiO2 as a photoanode. In this work, we fabricated anatase TiO2 nanoring/nanotube arrays and TiO2 nanotube arrays using an anodic oxidation method, confirmed by field-emission scanning electron microscopy (FESEM) and X-ray diffractometry (XRD), and then conducted the photoelectrochemical experiments with 1 M KOH and Na2SO4 solutions. The bias voltage, small impedance, negative flat-band potential, large capacitance, and depletion layer width in the anatase TiO2-KOH system were observed, leading to the stable and large photocurrent density. To understand the effects of KOH on the interface properties of TiO2/H2O, the electric double layers of anatase TiO2(001), (100), (101)/KOH interfaces were further investigated by calculating the ion-surface interaction with molecular dynamics simulations. It is noted that the number density of potassium ions has the same trend as that of oxygen atoms due to the layering effect in liquids and the strongest ionic hydration of K+ on anatase (101) is observed by analyzing the radial distribution function and coordination number. In addition, the electrostatic characteristics along the TiO2/KOH interfaces were analyzed based on the Grahame double layer model. The potential drops in the outer Helmholtz layer of anatase (001), (100), and (101) surfaces are 1.08, 0.26, and 0.51 V, respectively. Compared with TiO2-H2O systems, the larger potential drops in the TiO2-KOH system explain the phenomenon that KOH solute contributes substantially to a chemical bias in PEC reactions. At the same time, we estimated the depletion layer widths of anatase TiO2(001), (100), and (101) surfaces as 37.48, 173.25, and 64.49 A, respectively, which are of similar magnitude to the experimental results. Anatase TiO2(100) with the widest depletion layer is suggested in photocatalysis. These works provide a clear understanding of interfacial behavior of KOH on anatase TiO2 from a microscale, which can be used to explain the promotion effect of the KOH electrolyte and guide the design of TiO2 nanocrystals in the PEC system.

Frequency selective absorbing property (FSAP) is a key to realize radar frequency selective surfaces' stealth technology, which has great application prospects in national military industry. Different from traditional metal materials, herein, through the design of polyaniline microstructure as well as doping modification of the polymerization, polyaniline nanorings (PANI NRs) with certain electrical conductivity have been constructed. By constructing nanoring-shaped morphology, PANI NRs achieve strong reflection and great absorption of electromagnetic waves (EMWs) in different frequency ranges. These two properties are vital for realizing high-efficient FSAP. PANI NRs demonstrate negative permittivity within 50–1000 MHz frequency range where they can show strong EMWs reflection, and the negative permittivity is attributed to the plasma-like behavior of conductive network formed by plenty of overlapping nanorings. In addition, this porous structure also contributes to increase reflection and refraction of incident EMWs and then continuously consuming their energy, ensuring outstanding EMWs absorption property during 2–18 GHz frequency bandwidth.

Large-scale application of sustainable energy devices urgently requires cost-effective electrocatalysts to overcome the sluggish kinetics related to the oxygen evolution reaction (OER) under acidic conditions. Here, we first report the highly efficient electrocatalytic characteristics of α-Fe2O3 nanorings (NRs), which exhibits prominent OER electrocatalytic activity with lower overpotential of 1.43 V at 10 mA cm−2 and great stability in 1 M HCl, surpassing the start-of-the art Ir/C electrocatalyst. The significantly optimized OER activity of the α-Fe2O3 NRs mainly attributes to the synergistic effect of the excellent electrical conductivity and a large effective active surface because of their unique nanoring structure, disordered surface, and the dynamic stability of α-Fe2O3 NRs in acidic conditions.

Geometry design based plasmon hybridization represents an efficient means for pursuing desired spectral response and near-field enhancement in hybrid structures. Here, we propose to merge individual metal nanostructures into a superstructure to simultaneously realize plasmon mode inheritance and hybridization and electric near-field nanofocusing. As a model demonstration, we combine a metal nanoring supporting two localized surface plasmon resonances (LSPRs) and a metal nanocone sustaining one LSPR and one propagating surface plasmon polaritons (SPPs) mode into a hollow nanocone superstructure, and show numerically that such superstructure exhibits multiple plasmon resonance bands in the visible and near-infrared range and efficient nanofocusing of electric near-fields to the nanocone open apex. We further fabricate the designed superstructure with an ion-track membrane template method that allows for flexible control over relevant structural parameters by varying track etching time. Dark-field scattering measurements on single hollow nanocones confirm the presence of multiple plasmon resonances; surface-enhanced Raman spectroscopy further corroborates that the nanofocusing of electric fields plays a critical role in signal enhancement. We believe that such multi-resonant plasmonic superstructures with efficient near-field nanofocusing capability can find great potential in fundamental nonlinear optics and hot-carrier science studies and practical applications in surface-enhanced spectroscopies and broadband solar light harvesting.

Strong light–matter interaction at room temperature is significant for quantum optics, especially for exploring advanced nano-optical devices. We report herein a light–matter interaction in the strong coupling regime between plasmons confined within a single isolated bimetallic nanoring or nanocuboid and molecular excitons of J-aggregates under ambient conditions. We show that a bimetallic Au@Ag nanoring possesses larger enhanced electric field distribution than a Au@Ag nanocuboid, which enables bimetallic nanorings to couple with more excitons efficiently and overcome the large dissipation of the hybrid system. A large vacuum Rabi splitting of 200 meV was observed in this Au@Ag nanoring/J-aggregate hybrid. Finite-difference time-domain (FDTD) simulation and theoretical calculation show that there are ∼196 excitons in each Au@Ag nanoring/J-aggregate hybrid contributing to the coupling with a coupling constant of ∼111.3 meV, which is much higher than that of a single Au@Ag nanocuboid. Our work demonstrates that strong coupling can be realized via the enlargement of the overlap volume between excitons and plasmons, which can maximize the number of excitons contributing to coupling, giving rise to giant vacuum Rabi splitting. Our result provides additional flexibility to the experimental realization of novel plexcitonic architectures to attain strong coupling in an easily integrated and ultracompact platform.

The design of a facile and scalable method to synthesize solar light driven photocatalyst to generate H2 from water and degradation of toxic dyes from waste water is highly challenging field of research. Here, we are reporting a one pot synthesis of CdS/CdO colloidal nanocomposite with variable amount of CdS thickness and finally CdS nanoring. Different outward diffusion rate of oxygen and inward diffusion rate of sulphur ions generates hollow CdS/CdO nanocomposite based on nanoscale Kirkendall effect. Au nanoparticles (NPs) have been selectively deposited over CdS. Proper band alignment among CdO, CdS and Au results in a Z-type photocatalyst. Efficient spatial charge separation and large surface area lead to high photocatalytic dye degradation and Cr (VI) reduction in water. The amount of Cd in purified water is lesser than 0.003 ppm which maintains world Health Organization (WHO) guideline. The as developed catalyst is also active for generation of H2 from water in presence of solar light irradiation. Our present work may provide a promising way to fabricate an efficient photocatalyst for dye degradation and solar to fuel energy conversion using semiconductor (CdO)-semiconductor (CdS)-metal (Au) nanocomposite.

Excellent wave absorbers are key materials for reducing electromagnetic radiation pollution. In this work, novel γ-Fe2O3 nanoring/porous nitrogen-doped graphene (γ-Fe2O3 NR/PNG) composites with varying mass ratios were successfully synthesized as lightweight absorbers using a two-step solvothermal method in combination with a partial reduction process. The diameter of the uniform γ-Fe2O3 NRs is approximately 150 nm with a shell thickness of approximately 50 nm. The uniform γ-Fe2O3 NRs are dispersed onto PNG sheets. Compared with pure γ-Fe2O3 NRs and PNG, all γ-Fe2O3 NR/PNG composites exhibit better microwave absorbing performance, among which a γ-Fe2O3 NR/PNG composite with a 4:1 mass ratio of γ-Fe2O3 NR:PNG shows the best absorption over a broad bandwidth for its special nanoring and porous structure and excellent impedance matching. The minimum reflection loss (RLmin) reaches −40.18 dB at 7.80 GHz with a thickness of 2.5 mm; the absorption bandwidth (RL

Morphology evolution of calcite nanoparticles was investigated in detail during crystal growth induced by containing their aqueous slurry at a temperature of 95 °C. Formation of a single-crystalline nanoring that has a single cavity was confirmed soon after the slurry temperature was elevated to 95 °C. No templates were employed during the crystal growth process.

Using the linear combination of atomic orbitals real-time-propagation rt-TDDFT technique (LCAO-rt-TDDFT) and transition contribution maps, we study the optical and plasmonic features of a metal nanoring (made up of sodium atoms) with respect to the modulation in the ring thickness from a sharp edge (one-atom-thick) to a flat edge (four-atoms-thick). The birth of the localized surface plasmon resonance was accessed by many factors including the number of contributing electron-hole transitions, the relative strengths of these contributions, and the nature of the induced charge density oscillation. We reveal that the occurrence of a large number of contributing electron-hole transitions to an absorption peak cannot be treated as an indicator of plasmonicity. Nonetheless, plasmonicity can be accessed from the transition contribution map (occurrence of many spots with strong contributions and distributed on a large domain of energy) and from the profile of the induced charge density. Our results are useful for designing ultra-small plasmonic devices based on metal nanorings as building blocks.

Iron oxide (maghemite and magnetite) nanoparticles are the most commonly used magnetic materials in nanomedicine because of their high biocompatibility. However, their low saturation magnetization (60���90 emu/g) limits their applicability. Here, we report a new core���shell (Fe@Fe$_x$O$_y$) nanoring system, which combines the high magnetic saturation of a metallic iron core (220 emu/g) and the biocompatibility of an iron oxide shell. To produce these nanostructures, hematite (��-Fe$_2$O$_3$) nanorings were annealed in a H$_2$ gas atmosphere for different periods to optimize the amount of metallic iron percentage (��) in the system. Thus, nanostructures with different magnetic saturation (97 to 178 emu/g) could be obtained; based on their metallic iron content, these particles are labeled as Vortex Iron oxide Particle �� (VIP��). Micromagnetic simulations confirmed that the VIP�� nanorings exhibit a vortex configuration, guaranteeing low remanence and coercitivity. Moreover, the system shows good biocompatibility in various assays as determined through cell viability measurements performed using two different human cell lines, which were exposed to VIP78% for 24 h. Therefore, VIP�� nanorings combine a magnetic vortex state and biocompatibility with their high magnetic saturation and can thus serve as a platform that can be tuned during the synthesis based on desired biomedical application.

Precious metal nanostructures have attracted considerable attention for their unique optical properties. In this paper, a bilayer ring structure which realizes dual-band/three-band band-stop filters in the near-infrared range is designed. It has been verified with numerical simulation, by altering the radius of the two rings, the filter wavelength can be adjusted, during which efficiency of the filter (98%) is always achieved. Further investigation reveals that the filter effect is attributed to the synergistic effect with the absorption caused by the ohmic heat and the scattering by the resonance radiation, which is applicable to linearly polarized light and circularly polarized light simultaneously, promising potential applications in sensing and solar cells.

We have numerically investigated the tunable surface plasmon in graphene square-nanoring structure. Due to an enhancement of the local field, graphene surface plasmons (GSPs) can be strongly confin...

The positively charged amphiphiles hold great significance in supramolecular chemistry due to their good solubility, physiochemical and molecular recognition properties. Herein, we report synthesis, characterization and molecular recognition properties of dicationic amphiphile based on perylene diimide-tyrosine alkyl amide amine (PDI 3). PDI 3 showed the formation of nanoring architecture in self-assembled aggregated state (90% H2O–DMSO mixture) as observed by SEM and TEM studies. The diameter of the nanoring is around 30–50 nm with a height varying from 1–2 nm. The self-assembled aggregates of PDI 3 are very sensitive towards nucleoside triphosphates. Upon addition of ATP, PDI 3 showed decrease in absorbance and emission intensity at 535 and 580 nm (due to monomer state), respectively. The lowest detection limit for ATP is 10.8 nM (UV) and 3.06 nM (FI). Upon interaction of ATP with PDI 3, nanoring morphology transformed into spherical structure. These changes could be attributed to formation of ionic self-assembled aggregates between dicationic PDI 3 and negatively charged ATP via electrostatic and H-bonding interactions. The complexation mechanism of PDI 3 with ATP was confirmed by optical, NMR, Job’s plot, DLS, SEM and AFM studies. The PDI 3 displays low cytotoxicity toward MG-63 cells and can be successfully used for the detection of exogenous and endogenous ATP. The resulting PDI 3+ATP complex is successfully used as a ‘turn-on’ biochemical assay for monitoring phosphorylation of glucose.

We present an aluminum (Al) laminated nanostructure stacked on a glass substrate to produce highly transmitted narrowband ultraviolet (UV) filters. The laminated nanostructure was mainly composed of an Al nanohole array, and each Al nanohole had a coaxial Al nanoring at the bottom. This UV filter showed a single dominant peak with a high transmission over 50% and a narrow bandwidth less than 80 nm in the 200–400 nm waveband that was achieved based on the synergy of surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR). The electric field profiles of the laminated nanostructure indicate that SPR selects the transmission wavelength and LSPR contributes to single peak. This narrowband UV filter can be utilized in UV detectors.

A recent Research Article published in this journal by Matito and coworkers claimed that none of the oxidation states of a butadiyne-linked six-porphyrin nanoring exhibit global aromaticity or antiaromaticity. Here we show that this conclusion is incorrect. A combination of density functional theory (DFT) calculations and experimental NMR data provides compelling evidence for global (anti)aromaticity in a variety of six-porphyrin nanorings in their 2+, 4+ and 6+ oxidation states. The strength of the predicted ring current depends on the choice of DFT functional, so it is crucial to use a functional that reproduces the experimental 1H NMR chemical shifts in these cations.

A new member of the cycloparaphenylene double-nanohoop family was synthesized. Its π-framework features two oval cavities that display different shapes depending on the crystallization conditions. Incorporation of the peropyrene bridge within the nanoring cycles via bay-regions alleviates steric effects and thus allows 1:1 complexation with C60 in the solid state. This nanocarbon adopts a lamellar packing motif, and our results suggest that the structural adjustment of this double nanohoop could enable its use in supramolecular and semiconductive materials.