Copper Nanorods Research Articles

Integrated In Situ Fabrication of CuO Nanorod-Decorated Polymer Membranes for the Catalytic Flow-Through Reduction of p-Nitrophenol.

We developed a novel method to fabricate copper nanorods in situ in a poly(ether sulfone) (15 wt %) casting solution by a sonochemical reduction of Cu2+ ions with NaBH4. The main twist is the addition of ethanol to remove excess NaBH4 through Cu(0) catalyzed ethanolysis. This enabled the direct use of the resulting copper-containing casting dispersions for membrane preparation by liquid nonsolvent-induced phase separation and led to full utilization of the copper source, generating zero metal waste. We characterized the copper nanorods as presented in the membranes via scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV/vis spectroscopy. We could demonstrate that the rapid immobilization from reducing conditions led to the membrane incorporation of copper nanorods in a state of high reactivity, which also promoted the complete oxidation to CuO after fabrication. We further observed a large aspect ratio and crystal straining of the nanorods, likely resulting from growth around the matrix polymer. The entanglement with poly(ether sulfone) further facilitated a selective presentation at the pore surface of the final CuO-decorated membranes. The membranes also exhibit high water permeances of up to 2800 L/m2hbar. Our catalytic membranes achieved exceptionally high activities in the aqueous flow-through reduction of p-nitrophenol (p-NP), with turnover frequencies of up to 115 h-1, even surpassing those of other state-of-the-art catalytic membranes that incorporate Pd or Ag. Additionally, we demonstrated that catalytic hydrolysis of the reducing agent in water can lead to hydrogen gas formation and blocking of active sites during continuous catalytic p-NP hydrogenation. We illustrated that the accompanying conversion loss can be mitigated by facilitated gas transport in the water-filled pores, which is dependent on the orientation of the pore size gradient and the flow direction.

Finite element analysis of thermal sensitivity of copper nanorods, nanoellipsoids, nanospheres and core-shells for hyperthermia application

Hyperthermia is a cancer treatment strategy that involves raising the temperature of the afflicted tissues without disrupting the surrounding tissues. This study is focused on finite element analysis of copper, nanoellipsoids, nanorods, nanospheres and core-shells for potential hyperthermia application. The temperature of copper nanostructures was elevated using an external source to the desired temperature to destroy the cancerous cell. The COMSOL Multiphysics package was used to calculate how long it would take to achieve the desired temperature using different nanostructures of copper. Thermal sensitivity of the tested nanostructures was checked by putting them in a spherical domain of tissue. It was observed that copper nano-rod attained the highest temperature of 43.3 °C compared to other geometries. It was also found that these geometries attained thermal equilibrium just after 0.5 μs. However, the copper nano-ellipsoid had a higher core volume, which is utilized to determine the thermal sensitivity of the nanostructures. Noble metal (Au) coating was first found to be better than PEG polymer coating for investigating core–shell structures. The Au coating on the surface of the copper core resulted in a gradual decrease in temperature with an increasing volume coverage ratio. These results conclude that copper nanostructures can be suitable candidates for hyperthermia.

Localized surface plasmon resonance assisted photoredox catalysis using newly fabricated copper-nanorods: a decarboxylative approach towards carbon–hydrogen bond formation under visible light

Copper nanorods (Cu-NRs) exhibit significant plasmonic behavior, serving as efficient catalysts in an environmentally friendly decarboxylative process that converts alkyl carboxylic acids to alkane analogues under visible light.

Study on Nanomaterials with Inhibitory Effects on the Growth of Aspergillus niger.

In this paper, the inhibitory effect of various nanomaterials on the growth of Aspergillus niger was studied. Among them, copper nanorods had the most obvious inhibitory effect on the growth of Aspergillus niger. The phase of copper nanorods was modified by chitosan, and its inhibitory effect on the expansion of Aspergillus niger was measured. 1. Preparation of copper nanorods and chitosan@copper nanorods: Copper nanorods with a diameter of about 300-350 nm and a length of about 100-800 nm were prepared by the liquid-phase reduction method. The chitosan solution was prepared by using the characteristics of chitosan dissolved in dilute acid to prepare chitosan@copper nanorods and modify the phase of copper nanorods. 2. Determination of the inhibitory effect of various copper nanomaterials on the growth of Aspergillus niger, including Cuprous Oxide nanoparticles, copper nanorods, nano copper oxide, and copper hydroxide, which have certain inhibitory effects on the growth of Aspergillus niger. Among them, copper nanorods have a better effect. On this basis, chitosan@copper nanorods are obtained by modifying the phase of copper nanorods with chitosan. The measured antibacterial effect is that the EC50 value is 344 mg/L.

Alkali-promoted copper catalyst catalyze low-temperature water-gas shift reaction

The addition of alkali metal promoter is significant to improve the performance of copper catalyst in water–gas shift reaction (WGSR), but the previous theoretical work mainly focuses on the single crystal metal model like Cu(111), rather than the real supported copper clusters. In this paper, Cu4/TiO2(sub-nanometer), Cun/TiO2 (copper nanorod) were chosen to explore the effect of K on WGSR where K is located on TiO2 support, Cu/TiO2 interface, and copper clusters surface. Density functional theory calculation results show that only when K is on Cun/TiO2 and Cu(111) surfaces, can K promote water–gas shift reaction. Microkinetic modeling analysis shows that K mainly promotes the water–gas shift reaction by promoting the decomposition of H2O, and has little influence on the C-O bond formation like carboxyl and CO2. Combined with energetic, electronic and geometric analysis, on the surfaces of Cun/TiO2 and Cu(111), K mainly enhances the adsorption strength of H2O and reduces the barrier of H2O dissociation through direct bonding with oxygenate species, thereby improving the performance of WGSR. The copper clusters with sub-nanometer size cannot reveal the promotion effect of K, and the microkinetic modeling results of Cu(111) surface do not conform to the real situation, but the copper nanorod model can appropriately reflect the promotion effect of K. The structure unit of the active center is [TiO2−Cu−K]. The promotion of other alkali metals was explored, and the microkinetic modeling results show that the order of alkali metal promotion is as follows: Li < Na < K < Rb < Cs. The electronic structure analysis shows that the smaller the electronegativity of alkali metal, the lower the surface work function, the higher the surface dipole moment, and the stronger the promoting effect of alkali metal. This work not only reveals the origin of the K effect on WGSR, but also provides the accurate placement of K promoter.

Differential Analysis of Three Copper-Based Nanomaterials with Different Morphologies to Suppress Alternaria alternata and Safety Evaluation.

The overuse of copper-based fertilizers and pesticides over the last few decades has resulted in detrimental risks to our environment. Nano-enabled agrichemicals with a high effective utilization ratio have shown great potential for maintaining or minimizing environmental issues in agriculture. Copper-based nanomaterials (Cu-based NMs) serve as a promising alternative to fungicides. Three types of Cu-based NMs with different morphologies were analyzed for their different antifungal effects on Alternaria alternata in this current study. Compared to commercial copper hydroxide water power (Cu(OH)2 WP), all tested Cu-based NMs, including cuprous oxide nanoparticles (Cu2O NPs), copper nanorods (Cu NRs) and copper nanowires (Cu NWs), especially Cu2O NPs and Cu NWs, showed higher antifungal activity against Alternaria alternata. Its EC50 were 104.24 and 89.40 mg L-1, respectively, achieving comparable activity using a dose approximately 1.6 and 1.9-fold lower. Cu-based NMs could introduce the downregulation of melanin production and soluble protein content. In contrast to trends in antifungal activity, Cu2O NPs showed the strongest power in regulating melanin production and protein content and similarly exhibited the highest acute toxicity to adult zebrafish compared to other Cu-based NMs. These results demonstrate that Cu-based NMs could offer great potential in plant disease management strategies.

Anisotropic Growth of Copper Nanorods Mediated by Cl- Ions.

Anisotropic growth to form Cu particles of rod and wire shapes has been obtained typically in a complex system that involves both organic capping agents and Cl– ions. However, the sole effect of Cl– ions on the formation of Cu wires has yet to be fully understood, especially in an organic system. This present work determines the effect of Cl– ions on the morphologies of Cu particles in an organic phase without any capping agents. The results revealed that anisotropic Cu rods could be grown with the sole presence of Cl– ions. The rods have the (011) facets as the long axis, the (111) facets as the tip, and the (100) facets as the side surface. By increasing the Cl– ion concentration, more Cu atoms contributed to the formation of Cu rods and the kinetic growth of the length and the diameter of the rods varied. This suggests that Cl– ions have preferential adsorption on the (100) Cu surfaces to promote the anisotropic growth of Cu. Meanwhile, the adsorption of Cl– to the (111) and (100) surfaces at high Cl– concentrations regulates the relative growth of the particle length and diameter.

Photoelectrocatalytic degradation of wastewater and simultaneous hydrogen production on copper nanorod-supported coal-based N-carbon dot composite nanocatalysts

Cotton pulp black liquor (CPBL) is a highly concentrated organic wastewater with complex composition, and its direct discharge is extremely harmful to the environment. As an important industrial raw material, hydrogen (H2) has a wide range of applications in many fields such as energy and chemicals. In the study, the composite catalyst N-CDs/Cu NRs was prepared in two steps: firstly, coal-based nitrogen-doped carbon dots (N-CDs) were prepared by the ammonia hydrothermal cutting method using Xinjiang Wucaiwan coal as the carbon source; secondly, N-CDs were loaded onto the surface of copper nanorods (Cu NRs; prepared by a liquid-phase reduction) by a hydrothermal method. While characterizing the structure of the material, the performance of photoelectrocatalytic (PEC) degradation of CPBL and H2 production using N-CDs/Cu NRs was investigated: this PEC double reaction takes place in an H-type photoreactor, where the anode degrades CPBL and the cathode produces H2. The chemical oxygen demand removal rate (RTCODCr) of CPBL reached 94.33% and the yield of H2 reached 272.0 mmol in 60 min of reaction. The GC–MS results showed that all aldehydes, phenols, acids, amines, ethers, and most alkanes, ketones and esters in CPBL could be degraded after 60 min.

In Situ Partial Sulfidation for Preparing Cu/Cu2−xS Core/Shell Nanorods with Enhanced Photocatalytic Degradation

Herein, we report an approach to prepare Cu/Cu2−xS core/shell nanorods by in situ sulfidation of copper nanorods. Firstly, copper nanorods with tunable longitudinal surface plasmon resonances were synthesized by a seed-mediated method using Au nanoparticles as seeds. A convenient in situ sulfidation method was then applied to convert the outermost layer of Cu nanorods into Cu2−xS, to increase their stability and surface activity in photocatalytic applications. The thickness of Cu2−xS layer can be adjusted by controlling the amount of S source. The Cu/Cu2−xS core/shell nanorods exhibits two characteristic surface plasmon resonances located in visible and near-infrared regions, respectively. The photocatalytic performances of Cu nanorods and their derivatives were evaluated by measuring the degradation rate of methyl orange dyes. Compared with Cu nanorods, the Cu/Cu2−xS core/shell nanorods demonstrate more than a 13.6-fold enhancement in the degradation rate at 40 min. This work suggests a new direction for constructing derivative nanostructures of copper nanorods and exploring their applications.

Deformation mechanism of copper reinforced by three-dimensional graphene under torsion and tension

The mechanical behaviors of uniaxial torsional and tensional copper nanorod embedded with sp2-type hybrid graphene nanosheets (3DG/Cu) were investigated systematically using molecular dynamics methods. During the torsion process, graphene expanded the plastic deformation region of copper, while the plastic deformation in monocrystalline Cu cases was limited to a smaller area. 3DG/Cu responded to the torsion by one more plastic stage when plastic deformation spread along the length after the elastic response. Graphene improved the torsional loading capacity of the composite material, greatly extending the effective response range of the material by distributing the deformation of copper along with the graphene rather than being concentrated at a certain position like monocrystalline Cu. Generally, as the length of the model increased, this enhancement decreased. The copper portion of 3DG/Cu was divided into three areas during uniaxial tensile, a static region, a quasi-static region of the middle portion where the shear and necking occurred, and a dynamic area near the loading end. However, the inside graphene kept continuous until fracture. Furthermore, graphene improved the yield strain of copper by maintaining intact after copper failure. The greater the pre-loaded torsion angle, the smaller the yield strength and Young’s modulus of 3DG/Cu.

Ultrafast Dynamics of Colloidal Copper Nanorods: Intraband versus Interband Excitation

Colloidal copper nanorods (NRs) display transverse and longitudinal localized surface plasmon resonances. The longitudinal localized surface plasmon modes are tunable through the near‐infrared electromagnetic radiation energies with NR aspect ratios. Visible and near‐infrared transient optical response of the copper NRs is investigated under excitation conditions spanning intraband and interband excitation (0.79−3.50 eV). In both the visible and near‐infrared regions, the spectral response of the samples under intraband excitation (&lt;2 eV) differs substantially from their response under interband excitation (&gt;2 eV). However, the timescale of the electron−phonon coupling estimated from pump fluence‐dependent measurements (τep) is less sensitive to excitation conditions than reports for gold. τep shortens slightly from ≈616 fs with intraband excitation (at visible probe energies) to ≈565 fs with interband excitation. The observed dynamics correspond to an average sample electron−phonon coupling parameter varying across all conditions from 4.4 × 1016 to 6.4 × 1016 J m−3 K−1, which is similar to bulk copper. Furthermore, coherent acoustic phonons are observed for the longitudinal localized surface plasmon resonance with a range of oscillatory periods reflecting sample size dispersion.

Optical nano monopoles for interconnection electronic chips applications

Nano optical antennas have received a considerable attention in the interconnection electronic chips applications. In this paper, several investigations based on a semi-classical electromagnetic-quantum theory are performed to realize the possibility of using the armchair Single-Wall Carbon Nanotube (SWCNT) based monopole antennas for the interconnection between electronic chips in the optical regime. Two different SWCNT indices of (10,10) and (21,21) are conducted in this study for justification and compared against their identical monopoles based on Copper Nano-Rods (CNR). The material properties of the proposed nano-structures are retrieved from a quantum model to evaluate the proposed antennas performance. The proposed antennas based SWCNT10,10 and SWCNT21,21 are found to have the first resonance at 530 THz and 450 THz, respectively. Nevertheless, the antennas performances that are constructed from CNR compared to the relative ones based SWCNT. It is found that the CNR antennas provide a radiation efficiency (ղr) less than the provided by SWCNT antenna. Therefore, it is found that the antennas based SWCNT more suitable for wireless interconnections.

Two-Step Regulation Strategy Improving Stress Transfer and Poling Efficiency Boosts Piezoelectric Performance of 0-3 Piezocomposites.

The rapid development of flexible micropower electronics has aided the opportunity for the broader application of flexible piezoelectric composites (PCs) but has also led to higher requirements for their power generation. Among them, 0-3 PCs with embedded zero-dimension piezoparticle fillers, although low cost and easy to prepare, suffer from suboptimal output performance because of inherent structural defects. In this work, the voltage output was increased from 3.4 to 12.7 V under a force of 7 N, through first-step regulation by aligning the KNbO3 (KN) particles in the polydimethylsiloxane (PDMS) matrix; then, a significantly enhanced current output (from 0.7 to 4.5 μA) through second-step regulation by introducing copper nanorods (Cu NRs) interspersed in the gaps between the KN chains. Consequently, the proposed PC exhibits much higher power density, 37.3 μW/cm2, than that of random KN/PDMS and thus shows good potential for high-performance, flexible piezoelectric energy harvesters.

Optical absorption modeling of bilayer photoanode based on Cu@TiO2 plasmonic dye sensitized solar cells towards photovoltaic applications

A periodic array of core–shell Cu@TiO2 nanoparticle for plasmonic dye sensitized solar cells (DSSCs) in the wavelength range between 350 and 750 nm was studied. The size of copper nanospheres was 70 nm while the length and diameter of the copper nanorods were 100 and 10 nm, respectively. The UV–Visible absorption spectrum showed that the photo-anode based copper added TiO2 has 29.3% absorption capability compared with copper-free TiO2. TiO2 with shell thickness of 5 nm coated copper exhibited the absorption efficiency of 71.9%, while short circuit current density of 17.52 mA cm−2 for Ci@TiO2 photo-anode. This was attributed to a strong localized electric field around ultra-thin TiO2-coated copper nanospheres. The UV–Visible results of different geometries indicated that the spherical-shaped Cu@TiO2 nanoparticles induced the high absorption capability of 3.4% compared to rod-shaped Cu@TiO2 nanoparticles. The hybrid nanorods/nanospheres bilayer photo-anode showed the high optical UV–Visible absorption of 11.42% as compared with nanospheres/nanorods, ascribed to the large surface area for dye-loading excellent light scattering.

Facile synthesis of MoS2/Cu as trifunctional catalyst for electrochemical overall water splitting and photocatalytic CO2 conversion

Water splitting and CO2 conversion are emerging energy transfer techniques to generate hydrogen and low carbon fuel as eco-friendly energy sources. Herein, a frugal and facile approach is reported for decorating MoS2 nanosheets on copper nanorods to design MoS2/Cu architecture as a trifunctional catalyst for electrochemical water splitting and photocatalytic CO2 conversion. Under optimized conditions, MoS2/Cu electrocatalyst shows high performance at an overpotential of 252 mV for oxygen evolution reaction and 160 mV for hydrogen evolution reaction to attain 20 mAcm−2 and 10 mAcm−2 current densities in alkaline medium. The improved efficiency is mainly credited to the synergistic effect of MoS2 nanosheets and Cu nanorods architecture. The electrode delivered a cell voltage of ~1.508 V to impart about 10 mAcm−2 current density with high durability. Also, the negligible overpotential decay after running the cell for 12 h with 3000/HER and 2000/OER CV cycles suggests remarkable stability that makes it a promising electrocatalyst for energy production. The photocatalytic CO2 conversion activity was also measured, where MoS2/Cu exhibited a significant efficiency of CO2 to methane conversion (CH4 ~ 23 µmol g−1 h−1). Based on the obtained results, it is foreseeable that this work validates the significance of transition metals tuning for electrocatalysts and photocatalysts toward more efficient water electrolysis and CO2 reduction for potential large-scale energy applications.

A comparative study on the twinning boundaries of five-fold twinned copper and gold nanorods

Five-fold twinned copper and gold nanorods are important materials in heterogeneous catalysis. However, knowledges on the twinning boundary structures and their catalytic activities are quite limited. In this work, we conducted large-scale structure searching on the basis of forcefield potential and evolutionary algorithm, and precise quantum calculations on electronic structures and chemisorption energies using first-principles density functional theory. We determined the optimal twinning structures of the five-fold twinned copper and gold nanorods and analyzed their geometric differences via computing the standard deviation of metal bond lengths and the degrees of order. It was found that Au twinning boundary has a generally more regular structure but could involve noticeable point or line defects in some local areas, whereas Cu shows an incompact structure with fewer defects in the twinning region. Further by surface adsorption calculations using probe molecules of benzene and CO2, we show different degrees of chemisorption enhancement at various sites in or beside the twinning boundaries. Together with calculated charge transfer between adsorbates and metals or among different twinning regions, our results may provide some useful insights into the structural and chemisorption characteristics of twinned nanomaterials.

Heterometallic Seed-Mediated Growth of Monodisperse Colloidal Copper Nanorods with Widely Tunable Plasmonic Resonances.

We report a heterometallic seed-mediated synthesis method for monodisperse penta-twinned Cu nanorods using Au nanocrystals as seeds. Elemental analyses indicate that resultant nanorods consist predominantly of copper with a gold content typically below 3 atom %. The nanorod aspect ratio can be readily adjusted from 2.8 to 13.1 by varying the molar ratio between Au seeds and Cu precursor, resulting in narrow longitudinal plasmon resonances tunable from 762 to 2201 nm. Studies of reaction intermediates reveal that symmetry-breaking is promoted by rapid nanoscale diffusion in Au-Cu alloys and the formation of a gold-rich surface. The growth pathway features coevolving shape and composition whereby nanocrystals become progressively enriched with Cu concomitant with nanorod growth. The availability of uniform colloidal Cu nanorods with widely tunable aspect ratios opens new avenues toward the synthesis of derivative one-dimensional metal nanostructures, and applications in surface-enhanced spectroscopy, bioimaging, and electrocatalysis, among others.

Polyamide reverse osmosis membranes containing 1D nanochannels for enhanced water purification

Thin-film composite (TFC) reverse osmosis (RO) membrane is the gold-standard for desalination and water reuse. Recent literature highlights the importance of polyamide (PA) rejection layer containing nanovoids to manipulate the water permeability and salt rejection. In this study, a facile template-assisted approach was applied to generate one-dimensional (1D) nanochannels in the polyamide rejection layer of RO membranes by preloading copper nanorods inside the PA layer followed by acid etching. In addition, a TFC RO membrane containing 0D nanovoids was also fabricated to compare the dimensional effect of nanochannels on membrane morphologies and performances. Specifically, the TFC-0D membrane only exhibited 61% higher water permeability compared to that of the control TFC, while the TFC-1D membrane showed 126% higher water flux with similar NaCl rejection, probably due to the dimensional improvement of the nanochannels inside the rejection layer. This templates-assisted approach paves a feasible way for fabricating high-performance next-generation RO membranes.

Electrocatalytic production of hydrogen over highly efficient ultrathin carbon encapsulated S, P co-existence copper nanorods composite

Electrocatalysis plays a key role in energy conversion processes (such as hydrogen evolution reaction-HER) to several renewable energy technologies developed to reduce our dependence on fossil fuels. It is of great importance to design and develop robust electrocatalysts, for hydrogen production from water electrolysis, composed exclusively of low cost, non-precious elements that exhibit activity and stability comparable to those of the noble metals.In the present work, taking into account the high conductivity of carbon, a nitrogen-doped ultrathin carbon sheath covered Cu2S–Cu3P (Cu2S–Cu3P@C) as integrated architecture is synthesized. Remarkably, Cu2S–Cu3P@C, as a novel HER cathode operating in 0.5 M H2SO4 electrolyte exhibits a low onset potential of 48 mV, an overpotential of 85 mV at −10 mA cm−2 and a small Tafel slope of 34 mV dec−1. Meanwhile, after 80 h holding at −400 mA cm−2, the decrease in activity is negligible, demonstrating an excellent stability that outperforms most of the Cu-based electrocatalysts reported recently. The performance improvement is due to a unique carbon encapsulation structure, which could enhance the conductivity, facilitate the charge transfers and improve the corrosion resistance. This study will be beneficial to design and development of high performance non-precious metal electrocatalysts applied for electrocatalytic hydrogen generation.

Effect of the Nanorod Size on Energy Absorption at the Microlevel under Cyclic Loading

Molecular dynamics simulations were performed to investigate the effect of the size of the simulated nanoscale system on energy absorption under cyclic loading, as well as on further damage and failure of the system. Two copper nanorods with perfect crystal structure were considered: a base rod measured 50 × 5 × 5 lattice cells and a larger nanorod measured 200 × 20 × 20 cells. It was found that energy absorption is greatly affected by the ratio between the number of atoms simulating the grip and the total number of atoms in the system. Irreversible damage to the crystal structure in the larger system can be seen by a sharp increase in the maximum dispersion of atomic planes. With increasing nanorod size, the transformation of the crystal structure in regions subjected to cyclic loading leads to the formation of symmetric regions with a different lattice type at the same cyclic loading parameters.