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An Fe–10Cr–4Al alloy containing reactive elements developed for application in high-temperature liquid lead environments was analyzed after exposure in 600 and 750°C lead with dissolved oxygen for 1,000–2,000 h. Atom probe tomography, transmission electron microscopy, and X-ray scattering were all used to study the protective oxide formed on the surface. Exposure at 750°C resulted in a 2-μm thick oxide, whereas the 600°C exposure resulted in a 100-nm thick oxide. Both oxides were layered, with an Fe–Al spinel on top, and an alumina layer toward the metal. In the 600°C exposed material, there was a Cr-rich oxide layer between the spinel and the alumina. Metallic lead particles were found in the inner and middle parts of the oxide, related to pores. The combination of the experimental techniques, focusing on atom probe tomography, and the interpretations that can be done, are discussed in detail.

Solar-driven water evaporation is considered to be a viable and very efficient technology for fresh water production. Unfortunately, the photothermal membrane has a low absorptivity, low photothermal conversion and poor recyclability, which are difficult to meet the demands of self-floating solar driven evaporators in practical applications. Herein, a hierarchical nanostructure Ni3S2 has been prepared by in-situ growing method on Ni foam (NF), which shows excellent absorptivity, outstanding recyclable and high mechanically durable properties. The photothermal membrane was composed of hierarchical nanostructure Ni3S2@NF, which exhibited excellent solar absorption (93.13%) in the wavelength range of 250 nm–2500 nm and sustained anti-corrosion capacity for one month. In addition, the hierarchical nanostructure Ni3S2 @NF has good hydrophilicity and strong binding force, indicating this photothermal membrane exhibits good stability and outstanding photothermal conversion efficiency. An evaporation system based on 3D Ni3S2@NF membrane exhibited excellent water evaporation ability，the highest water evaporation rate (1.53 kg m−2 h−1) and the photothermal conversion efficiency （84.7%） under 1 sun illumination. In the desalination experiment, the water evaporation rate and photothermal conversion efficiency almost keep constant over 5 cycles tests and do not decrease compared with the experiment in pure water. This result demonstrated that the Ni3S2@NF membrane has shown good corrosion resistance and outstanding recyclability. Due to the simple preparation method, low cost, outstanding recyclability and high mechanical durability in the sea water, this Ni3S2@NF membrane have great potential for long-term solar distillation applications.

To effectively alleviate the ever-increasing energy crisis and environmental issues, clean and sustainable energy-related materials as well as the corresponding storage/conversion devices are in urgent demand. Silicon (Si) with the second most elemental abundance on the crust in the form of silicate or silica (SiO2) minerals, is an advanced emerging material showing high performance in energy-related fields (e.g. batteries, photocatalytic hydrogen evolution). For the improved performance in industry-scale applications, Si materials with delicate nanostructures and ideal compositions in a massive production are highly cherished. On account of the reserve, low cost and diverse micro-nanostructures, silicate minerals are proposed as promising raw materials. In the article, crystal structures and the reduction approaches for silicate minerals, as well as recent progress on the as-reduced Si products for clean energy storage/conversion, are presented systematically. Moreover, some cutting-edge fields involving Si materials are discussed, which may offer deep insights into the rational design of advanced Si nanostructures for extended energy-related fields.

Hypothesis A catanionic surface-active ionic liquid (SAIL) trihexyltetradecylphosphonium 1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate ([P6,6,6,14] [AOT]) is nanostructured in the bulk and at the interface. The interfacial nanostructure and lubricity may be changed by applying a potential. Experiments The bulk structure and viscosity have been investigated using small angle X-ray scattering (SAXS) and rheometry. The interfacial structure and lubricity as a function of potential have been investigated using atomic force microscopy (AFM). The electrochemistry has been investigated using cyclic voltammetry. Findings [P6,6,6,14] [AOT] shows sponge-like bulk nanostructure with distinct interdigitation of cation–anion alkyl chains. Shear-thinning occurs at 293 K and below, but becomes less obvious on heating up to 313 K. Voltammetric analysis reveals that the electrochemical window of [P6,6,6,14] [AOT] on a gold micro disk electrode exceeds the potential range of the AFM experiments and that negligible redox activity occurs in this range. The interfacial layered structure of [P6,6,6,14] [AOT] is weaker than conventional ILs and SAILs, whereas lubricity is better, confirming the inverse correlation between the near-surface structure and lubricity. The adhesive forces of [P6,6,6,14] [AOT] are lower at −1.0 V than at open circuit potential and +1.0 V, likely due to reduced electrostatic interactions caused by shielding of charge centres via long alkyl chains.

Photothermal therapy (PTT) has presented its inherent application value in cancer treatment. Nevertheless, single-functional photothermal materials cannot meet the precise diagnosis and treatment of cancer. Therefore, it is important to design a nanocomposite that has both high therapeutic efficiency and multimodal imaging capabilities. In our work, a new nanostructure of gold nanorods (AuNRs) with silver shells decorated by BaGdF5:Yb3+,Er3+ nanoparticle was synthesized by a simple way. The biostability of AuNRs is increased by coating with silver shells, and the AuNR@Ag nanoparticles can be used as excellent surface enhanced Raman scattering (SERS) probe. Moreover, the modification of BaGdF5:Yb3+,Er3+ nanoparticles provides the possibility of real-time optical imaging of the tumor area. Under the irradiation of NIR laser, the AuNR@Ag/BaGdF5:Yb3+,Er3+ nanocomposites (NCs) have strong upconversion emission and excellent photothermal conversion efficiency. Meanwhile, the NCs show low cytotoxicity and good biocompatibility in MTT cytotoxicity test. Moreover, the NCs are also exceptional contrast agents for CT imaging. For in vitro photothermal therapy test, NCs show excellent killing efficiency on tumor cells. Therefore, the multifaceted research of AuNR@Ag/BaGdF5:Yb3+,Er3+ multifunctional nanomaterials provides a break for high-efficiency tumor photothermal therapy and multimodal imaging.

Graphene is a two-dimensional material that can be folded into diverse and yet interesting nanostructures like macro-scale paper origami. Folding of graphene not only makes different morphological configurations but also modifies their mechanical and thermal properties. Inspired by paper origami, herein we studied systemically the effects of creases, where sp2 to sp3 bond transformation occurs, on the thermal properties of graphene origami using molecular dynamics (MD) simulations. Our MD simulation results show that tensile strain reduces (not increases) the interfacial thermal resistance owing to the presence of the crease. This unusual phenomenon is explained by the micro-heat flux migration and stress distribution. Our findings on the graphene origami enable the design of the next-generation thermal management devices and flexible electronics with tuneable properties.

The advancement and growth of nanotechnology lead to realizing new and novel multi-metallic nanostructures with well-defined sizes and morphology, resulting in an improvement in their performance in various catalytic applications. The trimetallic nanostructured materials are synthesized and designed in different architectures for energy conversion electrocatalysis. The as-synthesized trimetallic nanostructures have found unique physiochemical properties due to the synergistic combination of the three different metals in their structures. A vast array of approaches such as hydrothermal, solvothermal, seed-growth, galvanic replacement reaction, biological, and other methods are employed to synthesize the trimetallic nanostructures. Noteworthy, the trimetallic nanostructures showed better performance and durability in the electrocatalytic fuel cells. In the present review, we provide a comprehensive overview of the recent strategies employed for synthesizing trimetallic nanostructures and their energy-related applications. With a particular focus on hydrogen evolution, alcohol oxidations, oxygen evolution, and others, we highlight the latest achievements in the field.

In this study, the authors fabricated a hierarchically structured aluminum surface through facile hot-water treatment and abrasive machining. The developed surfaces were composed of nanoflakes exhibiting extreme wetting states, superhydrophilicity (θ s less than 5°) and superhydrophobicity (θ s greater than 150°) following salinization. The engendered surface morphologies composed of different length scales showed a significant influence on the wetting and durability characteristics. The stability of the observed Cassie state showed a direct correlation with the geometric parameters, particularly the interspatial distance. The critical surface tension for the transition from the Cassie to the Wenzel state increased with the interspatial distance. The surfaces structured with a smaller interspatial distance also exhibited high wetting resilience under dynamic conditions involving single-droplet impacts corresponding to We = 585 owing to a high negative capillary pressure. Further, the fine-structured hierarchical surfaces also exhibited appreciable antifogging and anticorrosion characteristics. Under simulated rain testing, the fine-structured hierarchical surfaces showed better durability than the coarser counterpart, enduring low contact angle hysteresis (CAH) (

Multicomponent binary metal oxide-involved hybrid structures with unique physicochemical properties have received extensive attention due to their fascinating electrochemical performance. Herein, a flexible strategy, which involves the preparation of dual-functional heterometallic Fe2M clusters and their subsequent sintering treatment, is developed to engineer novel 3D hierarchical porous structures assembled with MFe2O4 (M=Co, Mn, Ni and Zn) nanoparticles confined within carbon outer shell (denoted as MFe2O4@C HPSs). In this intriguing construction, it can be observed that MFe2O4@C HPSs comprised of carbon coated secondary MFe2O4 nanoparticles with an interconnected carbon network. The as-prepared MFe2O4@C HPSs possess combined advantages of high capacity of MFe2O4 and high conductivity of carbon. As expected, the MFe2O4@C HPSs offer a high reversible capacity, high cycling stability and superior rate performance. The interconnected conductive carbon shells facilitates fast ion and electron transport and accommodates the mechanical strain. In addition, nanosized MFe2O4 particles, which shorten the ion-transport path and provide extra electroactive sites, also improve the reaction kinetics. Moreover, these MFe2O4@C HPSs exhibit good structural integrity during repeated charging and discharging. The research perspective and strategy reported here are highly versatile and shed new light on the synthesis of other advanced electrode for various applications.

The pure and Zn doped CdS nanoparticles were synthesized using a simple method of co-precipitation. The structural, functional group and morphological analysis were carried through XRD, FTIR and SEM analysis. For supercapacitor applications, cyclic voltammetry analysis was studied for pure and Zn doped CdS nanostructures. From the XRD analysis all the samples were formed as a hexagonal crystal structure. SEM images show that the prepared Zn doped CdS formed like form as the flaks. The supercapacitor characterization (CV analysis) suggest that CdS and CdS-Zn electrodes are exhibit pseudocapacitive nature and it delivered the specific capacitance of 302 and 277 Fg−1 at a scan rate of 10 mV s−1.

The aim of this work was to study the single and combined effects of laboratory synthesised, purified, functionalised multi-walled carbon nanotubes (MWCNTs) and nanosilica (NS) particles on the physico-mechanical and dynamic properties of cement mortars. Portland cement was partially substituted by nanostructured MWCNTs (0.2, 0.4, 0.6, 0.8 and 1.0 wt%), then NS (2, 4, 6, 8 and 10 wt%) and finally both MWCNTs and NS in different ratios. The physico-mechanical and dynamic properties of the composite materials (compressive strength, bending strength, water consumption and initial and final setting times) were measured. The morphology of hardened samples was studied by scanning electron microscopy (SEM) and transmission electron microscopy was conducted to determine the size of the nanoparticles. The results showed that, compared with control samples, the compressive strength of the cement mortars containing MWCNTs increased by 27% at 28 days and the bending strength increased by 9.9% at early age. SEM images showed that the cement mortar containing 0.4 wt% MWCNTs had a more compact microstructure than then the control samples due to the bridging effect of the MWCNTs.

Proton exchange membrane fuel cell and direct methanol fuel cells have gained more attention due to high–energy density, remarkable conversion efficiency, and low emission. However, their widely practical application was hindered by the high usage, limited sources, and high price of Pt catalysts. To achieve more cost–effective catalytic systems, PtCu–based multi–metallic nanoparticles are highly efficient for the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). The incorporation of non–noble Cu metal can alter the properties of hybrids by forming new facets, planes, edges to promote the cleavage or formation of chemical bonds in catalytic reaction. This is a rapid growing area with numerous contributions from the interdisciplinary areas of nanocatalysis. This paper has summarized the recent progress in the past two years, in synthesizing PtCu–based alloys with various composition and morphologies, and critically discussed the effect of the catalyst preparation method, metal precursor, surfactant, reductant and heating temperature on nanostructure and electronic configuration. The important role of the composition, size, and morphology of PtCu bimetallic catalysts for electro oxidation reactions has been further established for structure–dependency studies. The challenges and perspectives of nanocatalysts for ORR and MOR discussed in this work is to provide further insights into rational design for cost–effective materials for energy.

Yb doped ZnO nanorods were prepared on glass substrates by the hydrothermal method in order to investigate the insertion of Yb ions in the ZnO matrix and the related morphological, structural and vibrational properties of the samples. X-ray diffraction patterns showed that the undoped and Yb doped ZnO nanorods exhibit the hexagonal wurtzite crystal structure with a preferential orientation along (1 0 1) direction and the size of the particle is found to be decreased with Yb content. SEM images show rods shape with more agglomeration in Yb doped ZnO nanorods. The vibrational study has also been performed using FT-IR spectroscopy which gives the presence of an absorption band corresponding to the stretching mode frequency of ZnO (Zn−O), the bands corresponding to organic precursors were no longer present in the FTIR spectrum after doping, which supports the incorporation of Yb ions into the ZnO lattice. Raman spectra confirmed the hexagonal wurtzite structure of pure and Yb doped ZnO nanoparticles with E2 (high) mode at 438 cm−1 and the presence of other possible defects. The aim of this study was to investigate the effect of Yb doping on the structural and vibrational properties of ZnO nanorods.

Pristine Cadmium Sulphide (CdS) and Polyvinylpyrrolidone (PVP) capped CdS nanoparticles have been synthesized by co-precipitation method. X-ray diffraction (XRD) analysis reveals that the CdS nanoparticles have a hexagonal structure. Field emission scanning electron microscopy (FESEM) with Energy dispersive x-ray spectroscopy (EDX) have been employed to study morphology and elemental composition for the prepared samples. From FESEM images, the average particle size of nanostructures is found to be 23.6 nm for PVP capped CdS and 16.2 nm for pristine CdS. Absorption spectroscopy reveals that the bandgap of 2.48 eV and 2.23 eV for pure CdS and PVP capped CdS nanoparticles respectively. Fourier transforms infrared (FTIR) spectroscopy provides information about the functional groups present in the samples. Out of these two samples, CdS nanoparticles with PVP polymer have been used as a gas sensing application at room temperature for various gases like N2, NH3, O2, and Ar because it shows the better properties than the pure CdS nanoparticles.

Herein, we reported a novel and a facile method to fabricated TiO2 nanowire arrays on Nitinol alloy substrate as electrode material for supercapacitors. The rutile TiO2 nanowire arrays on alloy substrates were developed using chemical vapor deposition technique with camphor as the source. A systematic study for the growth of nanostructure TiO2@NiTi has been carried out along with its exceptional physical and chemical properties for energy storage application. The growth of the nanostructure for different concentration at the elevated temperature has been studied through different characterization techniques like scanning electron microscopy, X-ray diffraction and Raman spectroscopy, which resulted in confirming the formation of rutile phase having length and diameter of 10 ± 3 µm and 80 ± 10 nm, respectively. In addition, the COMSOL simulation was carried out to determine the temperature gradient in the furnace tube at elevated temperature. The presence of nickel in the bi-metallic alloys played a vital role in the growth of TiO2 nanostructures array. The synthesized TiO2 nanowire arrays on Nitinol substrate exhibited the specific capacitance of ∼ 1F/g with long term stability, making it a potential candidate for supercapacitor applications.

The perovskite CH3NH3PbI3 films doped with Ag/SiO2 nanostructures on the surface of compact TiO2 layers have been synthesized. Ag/SiO2 nanostructures were embedded into the bulk of CH3NH3PbI3 perovskite by introducing them into the perovskite precursor’s solution. Ag/SiO2 nanostructures have insignificant effect on the perovskite films absorption spectra, but they significantly change the intensity and lifetime of CH3NH3PbI3 luminescence. The blue-shift of the luminescence intensity maximum in the CH3NH3PbI3 − Ag/SiO2 composite films, and time delay between the luminescence intensity maxima in perovskites without and with nanostructures indicate an increase of the charge transfer efficiency from perovskite film to titanium dioxide layer in the presence of Ag/SiO2 nanostructures.

Boron Nitride (BN) nanostructures have triggered extensive interest in various applications, be it field emitters, catalysts, adsorbents and bio-imaging, etc. It is essential but challenging to fabricate delicate BN structures of appreciable variability via exquisite yet scalable ways. We report herein the design of hierarchical BN nanobelt networks via a temperature-mediated assembly strategy. The precursor supramolecular architectures assembled from melamine and boric acid, which underwent different cooling procedures during their formation process, could be converted to hierarchical BN nanoribbons with varied width. Interestingly, the stacking of tiny crystals in BN nanobelts varies from a clearly demarcated pattern to an ambiguous state. Such tailorable micro-topology may offer opportunities for the unveiling of unique phenomena stemming from special inner organizations. This work allows the scalable production and the resultant hierarchical BN nanoribbon networks could exist in different states - powder, film and 3D aerogel forms, which facilitate their fitting into various scenarios.

The most common method for the electrochemical deposition of nanostructures is the potentiostatic double-pulse. In this work we report the electrodeposition of Ag nanoparticles on ITO using the single-pulse galvanostatic method, a technologically simpler and more scalable method that is rarely explored. The effect of the applied current on the particle density and the average size of the particles was evaluated at constant charge. The scanning electron microscopy (SEM) images show that the applied deposition current has a strong effect on the particle density of the deposits, and a rather weak effect on the mean particle size.

Aligned nanostructures possess a great importance in biomedical applications due to their ability to promote cell attachment, proliferation and migration in vitro. Polymeric nanofibers are among the most popular options because of their ease of fabrication by various electrospinning techniques. The microstructure and alignment of the electrospun nanofibers is controlled by altering the fabrication variables and collector mechanisms. This manuscript details the various technologies currently being employed to control the alignment of electrospun nanofiber. Role of polymer related parameters including the electrospinning voltage and nanofiber collector are also detailed. Aligned nanofibers provides several unique advantages in the area of biomedical and tissue engineering. Application of these aligned nanostructures as bioactive materials for controlling cell behaviour, wound dressing material, drug delivery, cancer therapeutics and biosensing are outlined.

This manuscript describes the effect of reaction temperature and time on the structural, morphology and optical properties of cetyltrimethylammonium bromide (CTAB) -assisted ZnO nanostructure grown through hydrothermal process. The samples are characterized by using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), UV–Vis spectroscopy and Fourier transform infra-red spectroscopy. XRD confirmed the hexagonal phase of ZnO. FESEM images estimated the average particle size of nanoparticles in the range of 20–50 nm. The optical band gap estimated by UV–Vis spectra were depends on reaction temperature and time and are in the range of 3.12 – 3.17 eV. A current–voltage (I–V) characteristic proves that conductivity of ZnO nanoparticles also depends upon hydrothermal reaction conditions.

Hybrid nanocrystals (NCs) with multiple components and junctions have attracted considerable attention due to their promising synergistic properties. In particular, great attention has been paid to the manipulation of buried multijunction heterointerfaces because they are closely related to the surface energy and carrier transfer of NCs. However, heterointerfaced NCs are usually constructed by sequential step-by-step pathways, and buried interfaces can only be formed along a given direction, resulting in the one and only spatial orientation of multiple interfaces. In this work, we demonstrate two types of Au-Ag2S-Cu2-xS NCs with disparate interfacial features. Specifically, the first type (Type I) is prepared through a routine two-step method and shows that Au domain close to the Ag2S-Cu2-xS interface; another type (Type II) is achieved by a facile one-pot synthesis procedure and contains Au domain with an interphase only with the Ag2S domain, far from the Cu2-xS domain. More importantly, type II NCs could not be formed through other traditional strategies and an underlying mechanism of formation is developed by monitoring the evolution process. Au@Ag core-shell NCs, metastable Au@Ag2S NCs and Janus Au-Ag2S NCs are formed successively before the Cu2-xS domain appears. We speculate that the Au@Ag2S intermediate plays an essential role in building the final complex nanostructure. We expect that such a simple and facile one-pot method will be used to fabricate additional asymmetric multicomponent NCs with distinctive interfacial features and promising potential applications.

A metal-resistant engineered Pichia pastoris was developed here to fulfil the metal bioleaching in aqueous conditions. Parent and recombinant yeasts were grown in YPD medium containing different concentrations of ion metals. XRD, electron microscopy and particle size analyser were used for the characterisation and the nanoparticle analyses. The nanoparticle production kinetics were studied by ICP-OES. The cytotoxicity of nanoparticles was assayed against human cell lines. Media colours changed to a range from purplish-brown to grey during early fermentation stages. The maximum biosorption capacities were recorded 81.23 and 493.35 mg/g for gold and palladium in batch conditions, respectively. Various physical investigations proved monodispersed spherical nanoparticles around 100 nm in size. Pure palladium nanoparticles and PdCl2 represented the least cytotoxic potency towards T47D and EPG85.257 cells. The results demonstrated that the genetically modified yeast is a cost-effective, high-throughput, robust, and facile system for metal biosorption.

The current state-of-the-art in nanotip synthesis relies on techniques that utilize elaborate precursor chemicals, catalysts, or vacuum conditions, and any combination thereof. To realize their ultimate potential, synthesized nanotips require simpler fabrication techniques that allow for control over their final nano-morphology. We present a unique, dry, catalyst-free, and ambient condition method for creating densely clustered, flower-like, sodium oxide (Na2O) nanotips with controllable tip widths. Femtosecond laser ablation of a soda-lime glass substrate at a megahertz repetition rate, with nitrogen flow, was employed to generate nanotips with base and head widths as small as 100 and 20 nm respectively, and lengths as long as 10 μm. Control of the nanotip widths was demonstrated via laser dwell time with longer dwell times producing denser clusters of thinner nanotips. Energy dispersive X-ray analysis reveals that nanotip composition is Na2O. A new formation mechanism is proposed, involving an electrostatic effect between ionized nitrogen and polar Na2O. The synthesized nanotips may potentially be used in antibacterial and hydrogen storage applications. PACS: 81 Materials science; 81.07.-b nanoscale materials and structures: fabrication and characterization; 81.16.-c methods of micro- and nanofabrication and processing

Background Natural biomaterials from bone-like minerals derived from avian eggshells have been considered as promising bone substitutes owing to their biodegradability, abundance, and lower price in comparison with synthetic biomaterials. However, cell adhesion to bulk biomaterials is poor and surface modifications are required to improve biomaterial-cell interaction. Three-dimensional (3D) nanostructures are preferred to act as growth support platforms for bone and stem cells. Although there have been several studies on generating nanoparticles from eggshells, no research has been reported on synthesizing 3D nanofibrous structures. Results In this study, we propose a novel technique to synthesize 3D calcium carbonate interwoven nanofibrous platforms from eggshells using high repetition femtosecond laser irradiation. The eggshell waste is value engineered to calcium carbonate nanofibrous layer in a single step under ambient conditions. Our striking results demonstrate that by controlling the laser pulse repetition, nanostructures with different nanofiber density can be achieved. This approach presents an important step towards synthesizing 3D interwoven nanofibrous platforms from natural biomaterials. Conclusion The synthesized 3D nanofibrous structures can promote biomaterial interfacial properties to improve cell-platform surface interaction and develop new functional biomaterials for a variety of biomedical applications.

Oxygen vacancies and lattice oxygen on the surface of nanoparticles play crucial roles in the magnetism of transition metal oxides. A fundamental understanding of the interactions between the 2p or...

Metal–organic framework (MOF) nanostructures provide unique opportunities in the fabrication of multifunctional polymer nanocomposites. However, achieving both enhanced mechanical properties and fi...

International audience; We report on high-dimensional quantum dynamical simulations of electron−hole separation in self-assembled mesomorphic nanostructures composed of donor−acceptor conjugated co-oligomers. The latter are based on perylene diimide (PDI) acceptor units combined with fluorene-thiophene-benzothiadiazole donor units, which form highly ordered, stacked structural motifs upon self-assembly. Simulations are shown for a first-principles parametrized model lattice of 25 stacked PDI units under the effects of an applied external field and temperature. The simulations are carried out with the multilayer multiconfiguration timedependent Hartree (ML-MCTDH) method with nearly 900 vibrational degrees of freedom and 25 electronic states. Temperature effects are included using the thermofield dynamics approach. A transition between a short-time coherent dynamics and a kinetic regime is highlighted. From a flux-overpopulation analysis, electron−hole dissociation rates are obtained in the range of 5−20 ns −1 in the absence of static disorder, exhibiting a moderate field and temperature dependence. These results for electron−hole separation rates can be employed as a benchmark to calibrate the parametrization of kinetic Monte Carlo simulations applied to much larger lattice sizes.

Abstract An effective technique for improving electrochemical efficiency is to rationally design hierarchical nanostructures that completely optimize the advantages of single components and establish an interfacial effect between structures. In this study, core–shell NiMoO4@Ni9S8/MoS2 hetero-structured nanorods are prepared via a facile hydrothermal process followed by a direct sulfurization. The resulting hierarchical architecture with outer Ni9S8/MoS2 nanoflakes shell on the inner NiMoO4 core offers plentiful active sites and ample charge transfer pathways in continuous heterointerfaces. Ascribing to the porous core–shell configuration and synergistic effect of bimetal sulfides, the obtained NiMoO4@Ni9S8/MoS2 as electrode material presents an unsurpassed specific capacity of 373.4 F g−1 at 10 A g−1 and remarkable cycling performance in the 6 M KOH electrolyte. This work delivers a rational method for designing highly efficient electrodes for supercapacitors, enlightening the road of exploring low-cost materials in the energy storage domain. Graphical Abstract

Low-dimensional nanostructures have been widely used as reinforcements for polymer nanocomposites. However, a majority of studies have considered the samples containing a single nanofiller or perfe...

Modifying electrochemical surface area (ECSA) and surface chemistry are promising approaches to enhance the capacities of oxygen cathodes for lithium–oxygen (Li–O2) batteries. Although various chemical approaches have been successfully used to tune the cathode surface, versatile physical techniques including plasma etching etc. could be more effortless and effective than arduous chemical treatments. Herein, for the first time, we propose a facile oxygen plasma treatment to simultaneously etch and modify the surface of Co3O4 nanosheet arrays (NAs) cathode for Li–O2 batteries. The oxygen plasma not only etches Co3O4 nanosheets to enhance the ECSA but also lowers the oxygen vacancy concentration to enable a Co3+-rich surface. In addition, the NA architecture enables the full exposure of oxygen vacancies and surface Co3+ that function as the catalytically active sites. Thus, the synergistic effects of enhanced ECSA, modest oxygen vacancy and high surface Co3+ achieve a significantly enhanced reversible capacity of 3.45 mAh/cm2 for Co3O4 NAs. This work not only develops a promising high-capacity cathode for Li–O2 batteries, but also provides a facile physical method to simultaneously tune the nanostructure and surface chemistry of energy storage materials.

Hypothesis The micrometer-sized gas bubbles of a liquid foam with a dispersed gas phase of > 74 vol% are polyhedral and surrounded by a continuous aqueous phase. The structure of a water-rich microemulsion with a water phase of > 74 vol% normally consists of oil droplets in water or is bicontinuous. We hypothesize that at these high water contents polyhedral water droplets in oil can also exist. Experiments We (a) carried out phase studies on the water-rich side of the phase diagram of the quaternary system water/NaCl – hexyl methacrylate – AOT, because AOT is known for its propensity to form water-in-oil structures and hexyl methacrylate can be polymerized, (b) measured the electrical conductivities and viscosities, and (c) visualized the nanostructure with freeze-fracture electron microscopy (FFEM). Findings We found narrow 1-phase regions emanating from the L3 phase of the oil-free water/NaCl – AOT system by adding small amounts of oil. In these regions the conductivities become extremely low and the viscosities are extremely high. In addition, FFEM images clearly show the foam-like nanostructure.

Recently, widespread attention has been devoted to the typical layered BiOCl or BiOBr because of the suitable nanostructure and band structure. However, owing to the fast carrier recombination, the photocatalytic performance of BiOX materials is not so satisfactory. Loading 1T phase WS2 nanosheets (NSs) onto Bi5O7Br NSs can improve the photocatalytic N2 fixation activity. Among these, the obtained 1T-WS2@Bi5O7Br composites with optimum 5% 1T-WS2 NSs display a significantly improved photocatalytic N2 fixation rate (8.43 mmol L−1 h−1 g−1), 2.51 times higher than pure Bi5O7Br (3.36 mmol L−1 h−1 g−1). And the outstanding stability of 1T-WS2@Bi5O7Br-5 composites is also achieved. Exactly, the photoexcited electrons from Bi5O7Br NSs are quickly transferred to conductive 1T phase WS2 as electron acceptors, which can promote the separation of carriers. In addition, 1T-WS2 NSs can provide abundant active sites on the basal and edge planes, which can promote the efficiency of photocatalytic N2 fixation. This work offers a novel solution to improve the photocatalytic performance of Bi5O7Br NSs.

Heterogeneous nanostructures that are defined as a hybrid structure consisting of two or more nanoscale domains with distinct chemical compositions or physical characteristics have attracted intense efforts in recent years. In this review, we focus on the introduction of a number of heterogeneous nanostructures derived using core-shell Ag–Pt nanoparticles as starting materials, including hollow, dimeric and composite structures and also highlight their application in catalyzing electrochemical reactions, e.g., methanol oxidation reaction and oxygen reduction reaction. This review not only shows the capability of core-shell Ag–Pt nanoparticles in producing various heterogeneous nanostructures as starting templates, but also highlights the structural design or electronic interaction that endows the heterogeneous nanostructures with enhanced catalytic properties either in methanol oxidation or in oxygen reduction. Further, we also make some perspectives for more heterogeneous nanostructures that may be prepared by using core-shell Ag–Pt particles or their derivatives so as to offer the readers the opportunities and challenges in this field.

Porous metal nanostructures exhibit excellent catalytic properties due to their high surface-to-volume ratios and abundant catalytic active sites. However, it is still challenging to control nanopores density and structural features in a facile route and the preparation of porous alloy nanorods for catalytic application has not been well explored. In this work, we demonstrate a synthetic strategy to fabricate highly porous Au–Ag alloy nanorods (P-AuAgNRs) by critically dealloying Ag atoms from homogeneous solid Au–Ag alloy nanorods (AuAgNRs). Combining the merits of the tunable plasmonic properties of noble metal nanorods, excellent stabilities of alloys, and superior catalytic activities of porous structures, we use the P-AuAgNRs as a Raman probe for the in situ monitoring of the catalytic oxidation of 3,3’,5,5’ tetramethylbenzidine (TMB) and reduction of 4-nitrothiophenol (4-NTP). We also compare their composition-dependent catalytic activities. The results show that P-AuAgNRs possess superior chemical stability and higher catalytic activity than those of core-shell structures due to synergistic structural and chemical mechanisms. This strategy provides a predictive design approach for the next-generation alloy catalysts with high-performance.

Potassium-selenium (K-Se) batteries have attracted more and more attention because of their high theoretical specific capacity and natural abundance of K resources. However, dissolution of polyselenides, large volume expansion during cycling and low utilization of Se remain great challenges, leading to poor rate capability and cycle life. Herein, N/O dual-doped carbon nanofibers with interconnected micro/mesopores (MMCFs) are designed as hosts to manipulate Se molecular configuration for advanced flexible K-Se batteries. The micropores play a role in confining small Se molecule (Se2–3), which could inhibit the formation of polyselenides and work as physical barrier to stabilize the cycle performance. While the mesopores can confine long-chain Se (Se4–7), promising sufficient Se loading and contributing to higher discharge voltage of the whole Se@MMCFs composite. The N/O co-doping and the 3D interpenetrating nanostructure improve electrical conductivity and keep the structure integrity after cycling. The obtained Se2–3/Se4–7@MMCFs electrode exhibits an unprecedented cycle life (395 mA h g−1 at 1 A g−1 after 2000 cycles) and high specific energy density (400 Wh kg−1, nearly twice the specific energy density of the Se2–3@MMCFs). This study offers a rational design for the realization of a high energy density and long cycle life chalcogen cathode for energy storage.

In this paper, using finite element method (FEM) as a three-dimensional simulation, the light trapping mechanism due to the use of plasmonic core/shell nanorod (PLCS-NR) array as well as its effect on absorption, generation, transfer of carriers and power conversion efficiency (PCE) in a perovskite solar cell (PSC) has been investigated. The short-circuit current density ( J sc ) increased due to the increase in the carrier generation rate in a PSC with a light-trapping architecture under the normal-angle sunlight (AM1.5G). Moreover, by choosing gold (Au) and silver (Ag) as the core and CuSCN as the shell in the PLCS-NR, the active layer (AL) absorption is increased compared to the planar structure. Using this proposed structure in the PSC can help improve the recombination rate and reduce it. The simulation results show that the device performance is highly dependent on the core and shell materials, and the height of the PLCS-NRs. Overall, an optimum height of 120 nm, a core radius of 10 nm, and Ag as the core were achieved for the PLCS-NRs in the PSC with J sc of 23.12 mA/cm2, the open-circuit voltage ( V oc ) of 1 V, and the PCE of 19.33%.

Molecular catalysts show powerful catalytic efficiency and unsurpassed selectivity in many reactions of interest. As their implementation in electrocatalytic devices requires their immobilization onto a conductive support, controlling the grafting chemistry and its impact on their distribution at the surface of this support within the catalytic layer is key to enhancing and stabilizing the current they produce. This study focuses on molecular bioinspired nickel catalysts for hydrogen oxidation, bound to carbon nanotubes, a conductive support with high specific area. We couple advanced analysis by transmission electron microscopy (TEM), for direct imaging of the catalyst layer on individual nanotubes, and small angle neutron scattering (SANS), for indirect observation of structural features in a relevant aqueous medium. Low-dose TEM imaging shows a homogeneous, mobile coverage of catalysts, likely as a monolayer coating the nanotubes, while SANS unveils a regular nanostructure in the catalyst distribution on the surface with agglomerates that could be imaged by TEM upon aging. Together, electrochemistry, TEM and SANS analyses allowed drawing an unprecedented and intriguing picture with molecular catalysts evenly distributed at the nanoscale in two different populations required for optimal catalytic performance., How do efficient hydrogen-oxidation molecular electrocatalysts connect onto their carbon nanotube conductive support? A coupled neutron scattering SANS and STEM electron microscopy study to observe soft active matter organizing on 3D nanosurfaces.

A new photosensitive dual-anisotropic conductive Janus film (PDCJF) is proposed for the first time. It is rationally designed and manufactured by facile electrospinning. PDCJF is firstly constructed using 2,7-dibromo-9-fluorenone (DBF) with photoconductive and luminescent properties. Janus nanofibers are respectively used as the building units to construct the top layer (T-PDCJF) and the bottom layer (B-PDCJF) of PDCJF. The two layers are tightly bonded to form PDCJF. Under light irradiation, there is photosensitive dual-anisotropic conduction in PDCJF, but there is no anisotropic conduction without light. Thus, the transition of PDCJF from mono-functional magnetism to tri-functionalities is realized under light and without light. The luminescence color of PDCJF is tunable and it emits white-light. This is made possible by modulating the amounts of luminescent substances and excitation wavelength. The microscopic Janus nanofibers used as building units and macroscopic Janus film structure ensure high photosensitive dual-anisotropic conduction and excellent fluorescence in PDCJF. The two-dimensional (2D) PDCJF is rolled to obtain three-dimensional (3D) Janus-type tubes and 2D plus 3D complete flag-like structures with exceptional multi-functionalities. The new findings can strongly guide in developing advanced multi-functional nanostructures.

The rigorous fabrication of electrode materials using upper-ranked porous precursor especially metal organic frameworks (MOFs) are challenging but appealing task to procure electrochemical energy storage and conversion system with altitudinous performance. Herein, we replenish the rational construction of atypical electrode of hollow Zn-Ni-Co-oxide (ZNCO) nanosheet arrays onto rGO garnished Ni foam (rGO/NF) via two step solution based method. Firstly, 2D Zn-Co-MOFs derived nanoleave arrays are prepared by co-precipitation method. Next, hollow and porous ZNCO nanostructure from 2D solid nanoleave arrays are achieved by ion-exchange and etching process conjoined with post annealing treatment. The as-fabricated hierarchical ZNCO nanosheet arrays offer large numbers of electroactive sites with short ion-diffusion pathways, reflecting the outstanding electrochemical performance in-terms of excellent specific capacity (267 mAh g-1) ultra-high rate capability (83.82% at 50 A/g) and long-term cycling life (~90.16%) in three electrode configuration for supercapacitor (SCs). Moreover, the hollow and porous ZNCO nanostructure responds as immensely active and substantial electrocatalyst for methanol oxidation with lowest onset potential of 0.27 V. To demonstrate the practicability, hybrid supercapacitor (HSC) device is constructed using ZNCO@rGO-NF nanostructure as positive and rGO decorated MOF derived porous carbon (rGO-MDPC) as negative electrode. The as-assembled ZNCO//rGO-MDPC ASC device delivers higher energy density of 61.25 Wh kg-1 at the power density of 750 W kg-1 with long-term cyclic stability (

Lithium-ion batteries (LIBs) have been used as energy storage devices for appliances of a wide range of sizes, for example, mobile phones, laptops, and electric vehicles. However, current commercial electrode materials in LIBs are facing severe challenges in energy density, safety, price, and recyclability, and this energy storage technology needs to be further developed for high power application in future. To address this challenge, nanostructured materials which possess large surface-to-volume ratios have been intensively studied as potential electrode materials to improve the battery performance. Among them, Tin (Sn) and nanostructured TiO2 have shown some advantages and disadvantages as electrode materials, for example Sn has high storage capacity but suffer from severe volume expansion during lithiation/delithiation. On the other hand, nanostructured TiO2 has small volume changes during Li ion insertion/extraction, but the poor ion mobility and electronic conductivity limited it electrochemical application. This review summarizes the recent development on Sn and TiO2 based nanostructure materials, particularly the synthesis method, their structure and battery performance as anodes for LIBs. Then, we discuss the strategies of developing new electrode materials and highlight a hybrid approach for designing and synthesizing high-performance electrode materials. The latest developments and related electrochemical performance of anode materials demonstrate that design hybrid nanostructure material is a low-cost and scalable approach to produce high-performance electrode materials for high-energy LIBs.

Metal-organic frameworks (MOFs), serving as precursors or templated to construct nanomaterials, which have gained great attentions in the field of electrocatalysis. However, their applications still remain some challenges due to poor conductivity and easy agglomeration. In this work, the MOFs-derived NiCo2S4@NiCo2O4 deposited on reduced Graphene Oxide (rGO) surface is designed by using a facile hydrothermal procedure. Attribute to the enlarged active surface area of the nanostructure and the strong synergistic effect between NiCo2S4 and NiCo2O4, as well as the excellent conductivity of rGO. The NiCo2S4@NiCo2O4-rGO catalyst displays ultrahigh hydrogen evolution reaction (HER) property and excellent stability, only need an overpotential of η10 = 95 mV to attain 10 mA cm−2 and deliver a small Tafel slope of b = 52 mV dec−1 in 1 M KOH. This work can provide a window to construct and develop new noble metal-free HER catalysts base on Ni-MOFs served as precursors.

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Water is one of the principal constituents by mass of living plant cell walls. However, its role and interactions with secondary cell wall polysaccharides and the impact of dehydration and subsequent rehydration on the molecular architecture are still to be elucidated. This work combines multidimensional solid-state 13C magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) with molecular dynamics modeling to decipher the role of water in the molecular architecture of softwood secondary cell walls. The proximities between all main polymers, their molecular conformations, and interaction energies are compared in never-dried, oven-dried, and rehydrated states. Water is shown to play a critical role at the hemicellulose–cellulose interface. After significant molecular shrinkage caused by dehydration, the original molecular conformation is not fully recovered after rehydration. The changes include xylan becoming more closely and irreversibly associated with cellulose and some mannan becoming more mobile and changing conformation. These irreversible nanostructural changes provide a basis for explaining and improving the properties of wood-based materials.

There is an increasing interest in using photoelectrochemistry for enhancing the signal-to-noise ratio and sensitivity of electrochemical biosensors. Nevertheless, it remains challenging to create photoelectrochemical biosensors founded on stable material systems that are also easily biofunctionalized for sensing applications. Herein, a photoelectrochemical immunosensor is reported, in which the concentration of the target protein directly correlates to a change in the measured photocurrent. The material system for the photoelectrode signal transducer involves using catecholate ligands to modify the properties of TiO2 nanostructures in a three-pronged approach of morphology tuning, photoabsorption enhancement, and facilitating bioconjugation. The catecholate-modified TiO2 photoelectrode is combined with a signal-off direct immunoassay to detect interleukin-6 (IL-6), a key biomarker for diagnosing and monitoring various diseases. Catecholate ligands are added during hydrothermal synthesis of TiO2 to enable the growth of three-dimensional nanostructures to form highly porous photoelectrodes that provide a three-dimensional scaffold for immobilizing capture antibodies. Surface modification by catecholate ligands greatly enhances photocurrent generation of the TiO2 photoelectrodes by improving photoabsorption in the visible range. Additionally, catecholate molecules facilitate bioconjugation and probe immobilization by forming a Schiff-base between their -COH group and the -NH2 group of the capture antibodies. The highest photocurrent achieved herein is 8.89 μA cm-2, which represents an enhancement by a factor of 87 from unmodified TiO2. The fabricated immunosensor shows a limit-of-detection of 3.6 pg mL-1 and a log-linear dynamic range of 2-2000 pg mL-1 for IL-6 in human blood plasma.

In this paper, we report the in situ growth of FF nanotubes examined via liquid-cell transmission electron microscopy (LCTEM). This direct, high spatial, and temporal resolution imaging approach allowed us to observe the growth of peptide-based nanofibrillar structures through directional elongation. Furthermore, the radial growth profile of FF nanotubes through the addition of monomers perpendicular to the tube axis has been observed in real-time with sufficient resolution to directly observe the increase in diameter. Our study demonstrates that the kinetics, dynamics, structure formation, and assembly mechanism of these supramolecular assemblies can be directly monitored using LCTEM. The performance of the peptides and the assemblies they form can be verified and evaluated using post-mortem techniques including time-of-flight secondary ion mass spectrometry (ToF-SIMS).

Low melting point eutectic systems, such as the eutectic gallium-indium (EGaIn) alloy, offer great potential in the domain of nanometallurgy; however, many of their interfacial behaviors remain to be explored. Here, a compositional change of EGaIn nanoalloys triggered by polydopamine (PDA) coating is demonstrated. Incorporating PDA on the surface of EGaIn nanoalloys renders core-shell nanostructures that accompany Ga-In phase separation within the nanoalloys. The PDA shell keeps depleting the Ga3+ from the EGaIn nanoalloys when the synthesis proceeds, leading to a Ga3+-coordinated PDA coating and a smaller nanoalloy. During this process, the eutectic nanoalloys turn into non-eutectic systems that ultimately result in the solidification of In when Ga is fully depleted. The reaction of Ga3+-coordinated PDA-coated nanoalloys with nitrogen dioxide gas is presented as an example for demonstrating the functionality of such hybrid composites. The concept of phase-separating systems, with polymeric reservoirs, may lead to tailored materials and can be explored on a variety of post-transition metals.

Chiral nanophotonic materials are promising candidates for biosensing applications because they focus light into nanometer dimensions, increasing their sensitivity to the molecular signatures of their surroundings. Recent advances in nanomaterial-enhanced chirality sensing provide detection limits as low as attomolar concentrations (10-18 M) for biomolecules and are relevant to the pharmaceutical industry, forensic drug testing, and medical applications that require high sensitivity. Here, we review the development of chiral nanomaterials and their application for detecting biomolecules, supramolecular structures, and other environmental stimuli. We discuss superchiral near-field generation in both dielectric and plasmonic metamaterials that are composed of chiral or achiral nanostructure arrays. These materials are also applicable for enhancing chiroptical signals from biomolecules. We review the plasmon-coupled circular dichroism mechanism observed for plasmonic nanoparticles and discuss how hotspot-enhanced plasmon-coupled circular dichroism applies to biosensing. We then review single-particle spectroscopic methods for achieving the ultimate goal of single-molecule chirality sensing. Finally, we discuss future outlooks of nanophotonic chiral systems.

In this work we investigate the effect of the symmetry in a 2-D arrays of gold nanoparticle on the sensitivity to the refractive index change. We demonstrate a generalized result that an asymmetric periodic arrangement of metallic nanoparticle leads to a higher sensitivity than a regular square of nanoparticle. Further decreasing the symmetry of the system by using asymmetric nanoparticle (nanorods, triangle) rather than symmetric nanoparticle (nanocylinder) will further improve this sensitivity. Finally, we suggest that such asymmetric nanostructure could operate as a SERS and LSPR plasmon based sensor by changing the polarization of the incident light.