Electric-field promoted C–C coupling over Cu nanoneedles for CO_(2) electroreduction to C_(2) products

Cu-based catalysts are the most promising candidates for electrochemical CO_(2)reduction(CO_(2)RR)to multi-carbon(C_(2))products.Optimizing the C-C coupling process,the rate-determining step for C_(2)product generation,is an important strategy to improve the production and selectivity of the C_(2)products.In this study,we determined that the local electric field can promote the C-C coupling reaction and enhance CO_(2)electroreduction to C_(2)products.First,finite-element simulations indicated that the high curvature of the Cu nanoneedles results in a large local electric field on their tips.Density functional theory(DFT)calculations proved that a large electric field can promote C-C coupling.Motivated by this prediction,we prepared a series of Cu catalysts with different curvatures.The Cu nanoneedles(NNs)exhibited the largest number of curvatures,followed by the Cu nanorods(NRs),and Cu nanoparticles(NPs).The Cu NNs contained the highest concentration of adsorbed K+,which resulted in the highest local electric field on the needles.CO adsorption sensor tests indicated that the Cu NNs exhibited the strongest CO adsorption ability,and in-situ Fourier-transform infrared spectroscopy(FTIR)showed the strongest*COCO and*CO signals for the Cu NNs.These experimental results demonstrate that high-curvature nanoneedles can induce a large local electric field,thus promoting C-C coupling.As a result,the Cu NNs show a maximum FEC_(2)of 44%for CO_(2)RR at a low potential(-0.6 V vs.RHE),which is approximately 2.2 times that of the Cu NPs.This work provides an effective strategy for enhancing the production of multi-carbon products during CO_(2)RR.

Bimetallic NiCo2S4 Nanoneedles Anchored on Mesocarbon Microbeads as Advanced Electrodes for Asymmetric Supercapacitors

Bimetallic Ni–Co sulfides are outstanding pseudocapacitive materials with high electrochemical activity and excellent energy storage performance as electrodes for high-performance supercapacitors.In this study,a novel urchin-like NiCo2S4@mesocarbon microbead(NCS@MCMB) composite with a core–shell structure was prepared by a facile two-step hydrothermal method.The highly conductive MCMBs offered abundant adsorption sites for the growth of NCS nanoneedles,which allowed each nanoneedle to fully unfold without aggregation,resulting in improved NCS utilization and efficient electron/ion transferin the electrolyte.When applied as an electrode material for supercapacitors,the composite exhibited a maximum specific capacitance of 936 Fg-1 at 1 Ag-1 and a capacitance retention of 94% after 3000 cycles at 5 Ag-1,because of the synergistic effect of MCMB and NCS.Moreover,we fabricated an asymmetric supercapacitor based on the NCS@MCMB composite,which exhibited enlarged voltage windows and could power a light-emitting diode device for several minutes,further demonstrating the exceptional electrochemical performance of the NCS@MCMB composite.

Construction of a few-layer g-C_3N_4/α-MoO_3 nanoneedles all-solid-state Z-scheme photocatalytic system for photocatalytic degradation

The suppression of the recombination of electrons and holes(e–h) and the enhancement of the light absorption of semiconductors are two key points toward efficient photocatalytic degradation.Here,we report a few-layer g-C_3N_4/α-MoO_3 nanoneedles(flg-C_3N_4/α-MoO_3 NNs) all-solid-state Z-scheme mechanism photocatalyst synthesized via a typical hydrothermal method in a controlled manner.The recombination of the photo-induced e–h pairs could be effectively restrained by the Z-scheme passageway between the flg-C_3N_4 and α-MoO_3 NNs in the composite,which could also promise a high redox ability to degrade pollutants.And it became possible for the prepared photocatalyst to absorb light in a wide range of wavelengths.The detailed mechanism was studied by electron spin-resonance spectroscopy(ESR).The low-dimensional nanostructure of the two constituents(α-MoO_3 NNs with one-dimensional structure and flg-C_3N_4 with two-dimensional structure) endowed the composite with varieties of excellent physicochemical properties,which facilitated the transfer and diffusion of the photoelectrons and increased the specific surface area and the active sites.The 10 wt% flg-C_3N_4/α-MoO_3 NNs showed the best photocatalytic performance toward RhB degradation,the rate of which was 71.86%,～2.6 times higher than that ofα-MoO_3 NNs.

Low-temperature Growth of Single-crystal SrCO_3 Nanoneedles

Single-crystal SrCO3 nanoneedles were synthesized in reverse micelles at low temperature. The products were characterized by X-ray diffraction, X-ray energy dispersive spectrometer, transmission electron microscopy and selected area electronic diffraction. The influences of experimental conditions on the morphologies of the products were discussed. The growth mechanism of SrCO3 nanoneedles in reverse micelles were proposed.

Green synthesis of silver nanoneedles using shallot and apricot tree gum

A green synthesis method to produce silver nanoneedles was described using shallot and apricot tree gum（ATG）.A fast,simple,and low cost method was used to synthesize silver with nanoparticle and nanoneedle shape from the silver nitrate solution.Shallot as a reducing agent and apricot tree gum（ATG） as a stabilizer and a capping agent were utilized to reduce and form silver ions into silver atoms with needle and particle shape.Moreover,high crystalline structures of silver nanoparticles（AgNPs） with diameters of 8-20 nm and silver nanoneedles with average diameters of 50-60 nm and lengths of 5-10 μm were consequently synthesized by shallot and the mixture of shallot and ATG.A self-assembly mechanism was proposed to indicate the formation of needle-like structures of spherical Ag NPs via carbon chains of ATG.The results indicate that the presence of ATG with shallot can transfer the reduced Ag NPs into the silver nanoneedle.The findings were characterized using X-ray diffraction（XRD）,ultra violet visible（UV-Vis） spectrometry,field emission scanning electron microscopy（FESEM）,and transmission electron microscopy（TEM） techniques.

Homogenous metallic deposition regulated by abundant lithiophilic sites in nickel/cobalt oxides nanoneedle arrays for lithium metal batteries

Although lithium(Li)metal delivers the highest theoretical capacity as a battery anode,its high reactivity can generate Li dendrites and"dead"Li during cycling,resulting in poor reversibility and low Li utilization.Inducing uniform Li plating/stripping is the core of solving these problems.Herein,we design a highly lithiophilic carbon film with an outer sheath of the nanoneedle arrays to induce homogeneous Li plating/stripping.The excellent conductivity and 3D framework of the carbon film not only offer fast charge transport across the entire electrode but also mitigate the volume change of Li metal during cycling.The abundant lithiophilic sites ensure stable Li plating/stripping,thereby inhibiting the Li dendritic growth and"dead"Li formation.The resulting composite anode allows for stable Li stripping/plating under 0.5 mA cm^(-2) with a capacity of 0.5 mA h cm^(-2) for 4000 h and 3 mA cm^(-2) with a capacity of3 mA h cm^(-2) for 1000 h.The Ex-SEM analysis reveals that lithiophilic property is different at the bottom,top,or channel in the structu re,which can regulate a bottom-up uniform Li deposition behavior.Full cells paired with LFP show a stable capacity of 155 mA h g^(-1) under a current density of 0.5C.The pouch cell can keep powering light-emitting diode even under 180°bending,suggesting its good flexibility and great practical applications.

An olsalazine nanoneedle-embedded inulin hydrogel reshapes intestinal homeostasis in inflammatory bowel disease

Inflammatory bowel disease(IBD)is a chronic and refractory condition characterized by disrupted epithelial barrier,dysregulated immune balance,and altered gut microbiota.Nano-enabled interventions for restoring gut homeostasis have the potential to alleviate inflammation in IBD.Herein,we developed a combination of olsalazine(Olsa)-based nanoneedles and microbiota-regulating inulin gel to reshape intestinal homeostasis and relieve inflammation.The Olsa-derived nanoneedles exhibited reactive oxygen species scavenging ability and anti-inflammatory effects in lipopolysaccharide-simulated macrophages.The composite of nanoneedles and inulin gel(Cu2(Olsa)/Gel)displayed a macroporous structure,improved bio-adhesion,and enhanced colon retention after oral administration.Mechanistically,the composite effectively downregulated pro-inflammatory cytokine levels and promoted epithelial barrier repair through anti-inflammatory and antioxidant therapies,resulting in significant alleviation of colitis in three animal models of IBD.Furthermore,analysis of gut microbiota revealed that Cu2(Olsa)/Gel treatment increased the diversity of intestinal microflora and decreased the relative abundance of pathogenic bacteria such as Proteobacteria.Overall,this study provides a self-delivering nanodrug and dietary fiber hydrogel composite for IBD therapy,offering an efficient approach to restore intestinal homeostasis.

Rapid Synthesis and Photoluminescence Properties of Eu-doped ZnO Nanoneedles via Facile Hydrothermal Method

Eu-doped ZnO nanoneedles with different doping concentrations were prepared via the facile hydrothermal method.The crystal structure,morphology and photoluminescence property of the ZnO nanoneedles were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）,photoluminescence spectroscopy（PL） and Raman spectroscopy.The results show that the europium ions are incorporated into the crystal lattice of ZnO matrix in trivalent ions.The nanoneedles are 2-3 μm in length and 100 nm in the tip diameter.PL and Raman measurements indicate that higher Eu^3＋ doping concentration may destroy the crystallization of the nanoneedles and decrease the ratio of IUV/IDLE,which is mainly due to the more defects in the doped ZnO nanoneedles.And the characteristic red emissions of Eu^3＋ ions are found by the PL spectroscopy with the Eu^3＋doping concentration increasing,which are attributed to the ^5D0→^7F0,^5D0→^7F1 and ^5D0→^7F2 transitions.

Room-temperature hydrogenation of halogenated nitrobenzenes over metal-organic-framework-derived ultra-dispersed Ni stabilized by N-doped carbon nanoneedles

Ultra-dispersed Ni nanoparticles(7.5 nm)on nitrogen-doped carbon nanoneedles(Ni@NCNs)were prepared by simple pyrolysis of Ni-based metal–organic-framework for selective hydrogenation of halogenated nitrobenzenes to corresponding anilines.Two different crystallization methods(stirring and static)were compared and the optimal pyrolysis temperature was explored.Ni@NCNs were systematically characterized by wide analytical techniques.In the hydrogenation of p-chloronitrobenzene,Ni@NCNs-600(pyrolyzed at 600°C)exhibited extraordinarily high performance with 77.9 h^(–1)catalytic productivity and>99%p-chloroaniline selectivity at full p-chloronitrobenzene conversion under mild conditions(90°C,1.5 MPa H2),showing obvious superiority compared with reported Ni-based catalysts.Notably,the reaction smoothly proceeded at room temperature with full conversion and>99%selectivity.Moreover,Ni@NCNs-600 afforded good tolerance to various nitroarenes substituted by sensitive groups(halogen,nitrile,keto,carboxylic,etc.),and could be easily recycled by magnetic separation and reused for 5 times without deactivation.The adsorption tests showed that the preferential adsorption of–NO2 on the catalyst can restrain the dehalogenation of p-chloronitrobenzene,thus achieving high p-chloroaniline selectivity.While the high activity can be attributed to high Ni dispersion,special morphology,and rich pore structure of the catalyst.

Solar-driven salt-free deposition evaporation for simultaneous desalination and electricity generation based on tip-effect and siphon-effect

Solar-driven desalination is a promising way to alleviate the freshwater shortage,while is facing challenges posed by low evaporation rates and severe salt accumulation.Herein,a high-performance twodimensional(2D) solar absorber with Co_(3)O_(4) nanoneedle arrays(Co_(3)O_(4)-NN) grown on the surface of reduced graphene oxide-coated pyrolyzed silk cloth(Co_(3)O_(4)-NN/rGO/PSC) was prepared,and a salt-free evaporator system was assembled based on the composite material and siphonage-the flowing water delivery.It is revealed that the evaporation enthalpy of water can be reduced over the 2D solar absorber grown with Co_(3)O_(4)-NN_T enabling an evaporation rate of up to 2.35 kg m^(-2) h^(-1) in DI water under one solar irradiation.The desalination process can be carried out continuously even with salt concentration up to 20 wt%,due to the timely removal of concentrated brine from the interface with the assistance of directed flowing water.Moreover,the 2D structure and the flowing water also provide an opportunity to convert waste solar heat into electricity in the evaporator based on the seebeck effect,ensuring simultaneous freshwater production and power generation.It is believed that this work provides insights into designing hybrid systems with high evaporation rate,salt resistance,and electricity generation.

Plasma-induced Mo-doped Co_(3)O_(4)with enriched oxygen vacancies for electrocatalytic oxygen evolution in water splitting

Heteroatomic substitution and vacancy engineering of spinel oxides can theoretically optimize the oxygen evolution reaction(OER)through charge redistribution and d-band center modification but still remain a great challenge in both the preparation and catalytic mechanism.Herein,we proposed a novel and efficient Ar-plasma(P)-assisted strategy to construct heteroatom Mo-substituted and oxygen vacancies enriched hierarchical spinel Co_(3)O_(4)porous nanoneedle arrays in situ grown on carbon cloth(denoted P-Mo-Co_(3)O_(4)@CC)to improve the OER performance.Ar-plasma technology can efficiently generate vacancy sites at the surface of hydroxide,which induces the anchoring of Mo anion salts through electrostatic interaction,finally facilitating the substitution of Mo atoms and the formation of oxygen vacancies on the Co_(3)O_(4)surface.The P-Mo-Co_(3)O_(4)@CC affords a low overpotential of only 276 mV at 10 mA cm^(−2)for the OER,which is 58 mV superior to that of Mo-free Co_(3)O_(4)@CC and surpasses commercial RuO_(2)catalyst.The robust stability and satisfactory selectivity(nearly 100%Faradic efficiency)of P-Mo-Co_(3)O_(4)@CC for the OER are also demonstrated.Theoreti-cal studies demonstrate that Mo with variable valance states can efficiently regulates the atomic ratio of Co^(3+)/Co^(2+)and increases the number of oxygen vacancies,thereby inducing charge redistribution and tuning the d-band center of Co_(3)O_(4),which improve the adsorption energy of oxygen intermediates(e.g.,*OOH)on P-Mo-Co_(3)O_(4)@CC during OER.Furthermore,the two-electrode OER//HER electrolyzer equipped with P-Mo-Co_(3)O_(4)@CC as anode displays a low operation potential of 1.54 V to deliver a current density of 10 mA cm^(−2),and also exhibits good reversibility and anticurrent fluctuation ability under simulated real energy supply conditions,demonstrating the great potential of P-Mo-Co_(3)O_(4)@CC in water electrolysis.

Synthesis of RE(OH)_2Cl and REOCl (RE=Eu, Tb) nanostructures

Anisotropic structures, nanoneedles, and nanospindles of rare earth hydroxychloride （RE（OH）2Cl） and oxychloride （REOCl） （rare earth=Eu and Tb） were synthesized. The rare earth hydroxychloride nanostructures were formed via a thermally assisted hydrolysis of the rare-earth sesquioxide nanocrystals. The morphological evolution of the nanostructures was studied using high-resolution transmission electron microscopy and scanning electron microscopy, while the structural evolution was investigated using X-ray diffraction techniques. The thermal stability of the rare earth hydroxychlorides was investigated using thermogravimetric analysis. The rare earth oxychloride nanospindles were synthesized via a simple heat-treatment of rare earth hydroxychloride nanospindles.

A Review of Nano/Micro/Milli Needles Fabrications for Biomedical Engineering

Needles,as some of the most widely used medical devices,have been effectively applied in human disease prevention,diagnosis,treatment,and rehabilitation.Thin 1D needle can easily penetrate cells/organs by generating highly localized stress with their sharp tips to achieve bioliquid sampling,biosensing,drug delivery,surgery,and other such applications.In this review,we provide an overview of multiscale needle fabrication techniques and their biomedical applications.Needles are classified as nanoneedles,microneedles and millineedles based on the needle diameter,and their fabrication techniques are highlighted.Nanoneedles bridge the inside and outside of cells,achieving intracellular electrical recording,biochemical sensing,and drug delivery.Microneedles penetrate the stratum corneum layer to detect biomarkers/bioelectricity in interstitial fluid and deliver drugs through the skin into the human circulatory system.Millineedles,including puncture,syringe,acupuncture and suture needles,are presented.Finally,conclusions and future perspectives for next-generation nano/micro/milli needles are discussed.

Enhanced electrochemical oxidation of perfluorooctanoic acid on Ti/SnO_(2)-Sb electrode by surface morphology regulation

Electrochemical oxidation is an effective method to degrade persistent organic pollutants.However,due to the limited catalytic activity of traditional thin film electrodes,the anodic oxidation process is slow and usually requires high energy consumption.Herein,Ti/SnO_(2)-Sb electrode with regulated surface structure was reported to enhance the performance for electrochemical oxidation of persistent organic pollutants.The electrode deposited with SnO_(2)-Sb nanoneedles(Ti/N-SnO_(2)-Sb)showed higher oxidation activity.Its kinetic constant for perfluorooctanoic acid(PFOA)oxidation was 2.0 h^(-1)and the total organic carbon removal rate was 81.7%(4 h)at a relatively low current density of 6 mA/cm^2.Compared with Ti/SnO_(2)-Sb thin film and nanoparticles,Ti/N-SnO_(2)-Sb significantly improved the electrochemical active area and·OH yield,and simultaneously reduced the electron transfer resistance,which enabled it to oxidize PFOA more rapidly even at a lower potential.This work provides a new strategy for promoting the electrochemical oxidation performance.

Generation of multi-hollow crystalline Mo fibres

Flower-like micrometer-sized crystalline Mo fibres have been prepared by directly heating Mo powder on Mo foil, under Ar atmosphere. ED, EDX, SEM and HRTEM studies reveal that each fibre consists of a single Mo crystal containing multi-hollow cores. A one-dimensional growth mechanism, on the basis of the one-dimensional thermal flow during fibre formation, is discussed.

Structural and morphological characterizations of ZnO nanopowder synthesized by hydrothermal route using inorganic reactants

Zinc oxide nanoscale powder has been synthesized by a hydrothermal route using zinc sulfate and sodium hydroxide. The as-prepared powder was annealed at 600 ℃ for 2 h and then characterized by X-ray diffraction（XRD）, scanning electron microscopy and infra-red Fourier transformed spectroscopy. XRD measurements have shown a Zn O hexagonal wurtzite polycrystalline structure with good crystallinity and the formation of a new sodium pyrosulfate phase in the as-prepared powder. The annealing improves the crystalline quality of the powder and transforms the sodium pyrosulfate phase to a sodium sulfate one. The thermal treatment does not affect the lattice parameters and the Zn–O bond length but improves the random orientation of the Zn O crystallites growth.Zn O crystallites have an interconnected-nano-needles morphology forming irregular shaped aggregates. The size of the crystallites is about 20 nm. EDX analysis has shown the presence of C and S in addition to Zn and O. FTIR spectra confirm the formation of Zn O and sodium sulfate. The synthesized Zn O powder has a very high crystalline quality and the used method is a very advantageous one for the fabrication of nanosized metal oxides from inorganic reactants for photo-catalysis applications.

Electrochemical behaviors of hierarchical copper nano- dendrites in alkaline media

In this study, hierarchical copper nano-dendrites （CuNDs） are fabricated via the electrodeposition method. The electrochemical behaviors of the as-obtained hierarchical CuNDs in 0.1 M NaOH aqueous solution are subsequently studied. The CuNDs experience a non-equilibritrm oxidation process when subjected to cyclic voltammetry （CV） measurements. The first oxidation peak O1 in CV is attributed to the formation of an epitaxial Cu20 layer over the surface of the hierarchical CuNDs. However, the second oxidation peak 02 in CV appears unusually broad across a wide potential range. In this region, the reaction process starts with the nucleation and growth of Cu（OH）2 nanoneedles, followed by the oxidation of Cu20. Upon the increase of potential Cu20 is gradually transformed to CuO and Cu（OH）2, forming a dual-layer structure with high productivity of Cu（OH）2 nanoneedles.