Copper Template Research Articles

Facile in-Situ Straining Platform for Transmission Electron Microscopy with Quantification of Strains

This work aims to design and model an experimental platform to perform in-situ straining experiments in a transmission electron microscope (TEM), enabling structural characterization of materials under tensile strain. The ability to visualize changes in the crystal structure of materials under strain can provide important insights into failure modes and improve understanding of process-structure-property relationships. Existing methods of in-situ straining typical involve complex sample preparation and are not well-suited to the study of thin films or sensitive battery materials. In this work, thin films of materials are deposited on a conventional TEM grid adhered to a copper template. The template is mounted in a Gatan 654 single tilt straining holder and strained within the TEM. Electron diffraction patterns are taken from the specimens, and strain can be calculated based on shifts in the Bragg reflections.An essential component of in-situ straining experiments is the quantification of applied strains. For our facile straining platform, we calculate the expected values of strain on our specimen using a finite element model. The finite element strain simulation data was compared with experimental data collected during in-situ straining experiments. Experimental results on a variety of material systems, including those applicable to lithium-ion batteries, are within the bounds of our model. Overall, the ability to accurately simulate in-situ strains using the finite element model enables researchers to better explain observation in the TEM, improve the reproducibility of the experiments, and optimize straining geometries to be tested. Figure 1

Electrosynthesis of Superhydrophilic Nickel Nanosheets on a Three-Dimensional Microporous Template: Applicability toward MOR.

In this report, a nickel nanoscaled morphology was synthesized by two-step cathodic electrodeposition on a microporous copper template. The resulting morphology, nanosheets formed on 3D micropores, offers incredible cyclic stability of almost 100% and facilitates transport mechanisms while significantly preserving the active surface area. The origin of the nanosheets is assumed to be the presence of a small amount of iron cations in the electrolyte bath during the final deposition step. By altering the deposition current density of this step, three samples were prepared and compared in terms of the resulting morphology, chemical composition, surface area, wettability, and activation toward the methanol oxidation Reaction. Results show that an increase in the deposition current density in the range of this study produces finer and denser nanosheets, a higher content of reduced iron, a larger surface area, and greater activity toward MOR. The current density for methanol oxidation was exceptional among all other studies on nickel-containing electrocatalysts, yielding a steady-state current density of 135 mA cm-2 at 600 mV versus SCE. All samples offered superhydrophilicity.

Multipath charge transfer in Cu-BTC@CuS@CeO2 double p-n heterojunction hollow octahedrons for enhanced photocatalytic amine oxidation

Hollow heterostructured catalysts have been widely investigated and applied in photocatalytic organic reactions. However, achieving hybrid catalysts with optimized hollow structure and controllable components is still a challenge. Herein, Cu-BTC@CuS@CeO2 ternary heterostructure hollow octahedrons were designed and prepared using a copper-based metal–organic framework (Cu-BTC) as both copper source and template. A thin CeO2 nanolayer was first formed and covered on the prepared Cu-BTC octahedron surface through a hydrothermal process. In the meanwhile, the Cu-BTC octahedrons were controllably etched in this hydrothermal process, leading to the formation of Cu-BTC@CeO2 hollow octahedron. The following sulfidation reaction produced Cu-BTC@CuS@CeO2 double p-n heterojunction hollow octahedrons. Benefiting from the novel hollow octahedron double p-n heterojunctions, excellent visible-near infrared light absorption, and fast charge transfer and separation, the obtained Cu-BTC@CuS@CeO2 hollow octahedron hybrid catalyst exhibited a significantly higher photocatalytic activity toward the oxidative coupling of amines to imines at room temperature under visible-near infrared light irradiation compared to the control single component catalysts (Cu-BTC, CeO2, and CuS) and binary hybrid catalysts (Cu-BTC@CeO2, Cu-BTC@CuS, and CuS@CeO2). The enhanced charge transfer at the double p-n heterojunction was discussed. Meanwhile, the photocatalytic oxidation products and reaction mechanism were investigated by surface-enhanced Raman spectroscopy, gas chromatography-mass spectrometry, and pyridine adsorption FT-IR spectroscopy. This work presents a promising strategy for the design of multi-component hollow heterostructure catalysts.

Development of improved technology for producing graphene-like coating by LPCVD method

The object of research in this work was the coating of oxygraphene on a silicon single crystal substrate. In the work, the LPСVD (Low Pressure Chemical Vapor Deposition) method of deposition from the gas phase at low pressure is used to obtain graphene-like coatings on heat-resistant materials. A feature of the proposed LPCVD method in comparison with the classical method of deposition from the gas phase CVD (Chemical Vapor Deposition) by the method of catalytic decomposition of carbon-containing gas followed by the deposition of a graphene-like coating on a copper template is the use of a higher partial gas pressure, which leads to the deposition of graphene-like waste not only on the surface of the copper template-catalyst, but also in the entire volume of the reaction chamber and the materials introduced into it. A monocrystalline silicon template was used as a model for coating. The resulting coatings of different thicknesses were examined by scanning electron microscopy, Raman spectroscopy, and density was assessed by helium pycnometry. Based on the analysis of the results obtained using the method of scanning electron microscopy, the possibility of varying the thickness of the oxygraphene coating was shown. In addition, the formation of oxygraphene on a silicon single crystal substrate was confirmed by the Raman spectroscopy method, namely the presence of characteristic peaks in the spectra of the studied materials. Using the helium pycnometry method, a decrease in the density of the coated material from 2.25 g/cm3 to 2.08 g/cm3 was found. It was established that the greater the coating thickness, the lower the density. The general analysis showed that the developed LPСVD technology allows obtaining an oxygraphene coating on materials of any shape, porosity, size and resistant to temperatures above 600 °С in order to functionalize their surface and improve and improve their properties.

Scalable Strategy to Directly Prepare 2D and 3D Liquid Metal Circuits Based on Laser-Induced Selective Metallization.

Selective wetting of a gallium-based liquid metal on copper circuits is one of the ways to prepare liquid metal circuits. However, the complex fabrication processes of an adhesion layer between copper circuits (or patterns) and substrates were still inevitable, limiting scalable applications. Our work developed a facile way to directly prepare 2D and 3D liquid metal circuits by combining laser-induced selective metallization and selective wetting for the first time. The copper template was obtained on elastomers using laser-induced selective metallization, and high-resolution liquid metal circuits were fabricated by brushing Galinstan on the copper template in the alkali solution. The distribution of Cu element not only was on the top surface but also extended to the interior of the elastomer substrate. This revealed that the Cu layer prepared by laser-induced selective metallization is born to firmly embed into the substrate, which endowed the circuits with strong adhesion, reaching the highest 5B level. Moreover, the prepared liquid metal circuits (or patterns) had a typical layered structure. The liquid metal circuits exhibit good flexibility, stretchability, self-healing ability, and acid-alkaline resistance. Compared with the traditional methods of patterning liquid metals, fabricating liquid metal circuits based on laser-induced selective metallization has irreplaceable advantages, such as strong adhesion between circuits and substrate, fabricating 3D circuits, good acid-alkaline resistance, cost-effectiveness, maskless use, time savings, arbitrary design of patterns, and convenient operation, which endow this method with great application prospect.

Ultra-sensitive flexible piezoresistive pressure sensor prepared by laser-assisted copper template for health monitoring

The flexible sensors with microstructures have attracted much attention due to their ultrahigh sensitivity. To develop a controllable method for large-scale preparation of microstructures is the key to promoting the application of the flexible sensors. Herein, combining the laser processing technology with a copper template commonly used in roll-to-roll process, ultra-sensitive flexible piezoresistive pressure sensors with carbon nanotubes (CNTs) conductive layers on the ridge-shaped microstructures were fabricated and the effects of structure parameters on the performance of the sensors were systematically studied. Experimental results showed that the sensitivity of the sensors is positively correlated with the height h and spacing d of the ridge-shaped microstructure which are determined by laser processing parameters. The sensitivity of the sensor with the ridge-shaped microstructure (h=150 µm, d=200 µm) is as high as 1150.9 kPa−1 at an applied pressure< 50 Pa. Meanwhile, the sensor shows excellent stability (>2000 cycles), rapid response time (43 ms) and recovery time (15 ms). Besides, the sensor was used to detect human physiological signals such as speaking, cheek bugling and artery pulse. These results indicate that combining the laser processing with copper templates has great potential in the controllable and large-scale fabrication of flexible sensors with microstructures for health monitoring.

Self-Assembly of [3]Catenane and [4]Catenane Based on Neutral Organometallic Scaffolds

Transition metal-mediated templating and self-assembly have shown great potential to construct mechanically interlocked molecules. Herein, we describe the formation of the bimetallic [3]catenane and [4]catenane based on neutral organometallic scaffolds via the orthogonality of platinum-to-oxygen coordination-driven self-assembly and copper(I) template–directed strategy of a [2]pseudorotaxane. The structures of these bimetallic [3]catenane and [4]catenane were characterized by multinuclear NMR {1H and 31P} spectroscopy, electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), and PM6 semiempirical molecular orbital theoretical calculations. In addition, single-crystal X-ray analyses of the [3]catenane revealed two asymmetric [2]pseudorotaxane units inside the metallacycle. It was discovered that tubular structures were formed through the stacking of individual [3]catenane molecules driven by the strong π–π interactions.

In-situ deposition of three-dimensional graphene on selective laser melted copper scaffolds for high performance applications

Currently, three-dimensional graphene (3DG) fabrication was restricted by the complicated process, strict chemical reactions as well as structural accuracy. Herein we creatively propose a bottom-up strategy that leverages the selective laser melting (SLM) technique to manufacture a three-dimensional (3D) porous copper template. Graphene was then in-situ grown via chemical vapor deposition (CVD) on the obtained porous Cu template, forming 3DG composites. A combination of conventional graphene growth via CVD technique with SLM fabricated scaffold templates enabled an accurate design and regulation of 3DG from macro-structure (unit type, porosity, aperture) to micro-structure (texture, surface quality) through an elaborately manipulated porous copper scaffold. The 3DG/copper scaffold could achieve around 88% and 27% enhancement in electromagnetic interference (EMI) shielding and thermal diffusion, respectively. Particularly, the highest EMI shielding efficiency (SE) can reach up to 47.8 dB at 2.7 GHz and exhibit an average SE of 32.3 dB at the range of 2–18 GHz. The synergistic shielding mechanisms accounted for the improvement derived from the use of hybrid composite materials and precise architecture of the SLM porous structure.

Anion-regulated selective growth ultrafine copper templates in carbon nanosheets network toward highly efficient gas capture

Controlling micropore size is the core for synthesizing highly efficient adsorbents for gas adsorption and separation engineering. Porous carbon prepared by traditional methods usually lacks competitiveness due to the random micropore size or complex process. Herein, we report a novel strategy for synthesizing nitrogen doped carbons nanosheets (Cu-NDPCs) with unimodal ultra-micropore based on the metal-organic covalency and the anion regulated in situ copper template. The thickness of single Cu-NDPCs is about 4.2 nm. In the presence of Cl−, the porosity of Cu-NDPCs can be tuned at 4.1–4.8 Å by adjusting the pyrolysis temperature. Among them, Cu-NDPC-800 has unique carbon nanosheets networks structure, ultrahigh surface area (2150 m2 g−1), large micropore volume (0.92 cm3 g−1) and abundant surface N doping (5.33%). As an adsorbent, it exhibits superhigh C2H2, C2H6, C3H8 and CO2 uptakes (6.7, 7.0, 11.4 and 4.4 mmol g−1) and corresponding x/CH4 or CO2/N2 IAST selectivities (12.9, 17.8, 468.6, 4.3 and 17.1) under ambient conditions. Meanwhile, the Cu-NDPC-800 possesses excellent cyclic stability.

Fabrication and Thermal Characterization of Composite Cu-CNT Micropillars for Capillary-driven Phase-Change Cooling Devices

ABSTRACTThis paper presents the fabrication, testing, and modeling of an array of composite copper-carbon nanotubes (Cu-CNT) micropillars as a wick structure for potential application in passive phase-change cooling systems. This novel wick structure has a larger spacing at the base of the micropillars to provide a higher liquid permeability and mushroom-like structures on the top surface of the micropillars with a smaller spacing to provide a greater capillary pressure. The composite Cu-CNT micropillars were fabricated by an electrochemical deposition method on a patterned copper template. Cauliflower-like nanostructures were then grown on the top surface of the micropillars using chronoamperometry technique to improve the capillary pressure and thermal performance of the wick structure. After successful fabrication of the micropillars, a series of tests were conducted to quantify the thermal performance of the wick structures. The results demonstrate superior thermal and corrosion performances for composite Cu-CNT micropillars compared to those of copper micropillars. Additionally, a thermal resistance network analysis was conducted to model the thermal performance of the fabricated mushroom-shaped micropillar array. Model predictions were compared with the experimental results and good agreement was observed.

Use of pyrophosphate and boric acid additives in the copper-zinc alloy electrodeposition and chemical dealloying

Over the last decade, nanoporous metals have attracted a growing attention due to the combination of structural and functional properties, such as their very high surface to volume ratio and mechanical rigidity. A recent and versatile process producing nanoporous metals is the dealloying of an initial alloy, i.e. the selective dissolution of the more reactive element of the alloy. In this work, we report on a method of CuZn alloy formation, without the use of furnaces or expensive techniques, and its subsequent chemical dealloying leading to nanoporous copper. Co-electrodeposition of CuZn alloys on a copper substrate is performed using pyrophosphate as a complexing agent in presence of boric acid, copper sulfate and zinc sulfate. The electrochemical behavior of this system is characterized by cyclic voltammetry, showing that a copper-zinc alloy is formed at −1.5 V vs. SCE. Cauliflower-like Zn-rich γ-brass and ε-brass coatings are obtained by co-electrodeposition. The thickness, the structure and the composition of the electrodeposited alloy can be tuned by varying the electrodeposition conditions. Thicker and rougher coatings with a higher zinc content are formed at more cathodic conditions. The electrodeposited CuZn coatings were chemically dealloyed, and a two-step dealloying protocol leads to open-framework nanoporous copper templates, which are a material of interest for energy storage, biosensors, and catalysis applications.

Hierarchical Nanoporous Carbon Templated and Catalyzed by the Bicontinuous Nanoporous Copper for High Performance Electrochemical Capacitors

AbstractTo enhance the performance of electrochemical capacitor, the nanostructured carbon materials with large surface area, appropriate pore distributions, suitable electronic conductivity and perfect chemical stability are pursued. Herein, the highly graphitized hierarchical porous carbon with well‐defined porosity are fabricated. For the first time, the novel bicontinuous nanoporous copper is used as both the template and the catalyst to synthesize the porous carbon materials. The as‐prepared porous carbon demonstrates a high specific surface area of 1826 m2 g−1 benefitting from the bicontinuous nanoporous copper template and KOH activation. By electrochemical test, the nanoporous carbon material displays a specific capacitance of 210 F g−1 at a current density of 0.2 A g−1 within 6 M KOH aqueous solution. The material demonstrates excellent cycling stability with a 95.4% capacity retention for 10 000 cycles with a current density of 1 A g−1. The present work provides a facile approach for fabrication of carbon‐based electrode materials for electrochemical capacitors.

Micro-EDM method to fabricate three-dimensional surface textures used as SERS-active substrate

Based on micro electrical discharge machining (micro-EDM) method, three-dimensional surface textures were fabricated by constituting arrayed paraboloid-shaped micro-cavities on a copper template, and these surface textures were intended for surface-enhanced Raman scattering (SERS) active substrate. By lowering discharge energy, the inherent discharge craters and bulges were limited to be in nanoscale, and thereby the fabricated surface texture could be characterized as a micro-nano hierarchical structure. Raman spectra were measured on fabricated surface textures using Rhodamine 6G as the probe molecule, and results showed that the characteristic peaks of R6G molecules can be successfully identified under a low concentration of 10−7 M. In addition, the strongest Raman spectra intensity was observed on the surface texture that has the largest apparent area (S) per unit interval space (d) and per unit peak-to-valley height (h). This is mainly attributed to the fact that the surface texture with larger S/(d × h) would adsorb more probe molecules and provide higher density of SERS hot-spots. As a whole, the fabricated surface textures exhibited good SERS performances by providing an enhancement factor of greater than 107. The works conducted in this study are expected to provide a novel thought to fabricate SERS-active substrate, and extend the application fields of micro-EDM technology as well.

Facile Fabrication of Cu₂O Nanobelts in Ethanol on Nanoporous Cu and their Photodegradation of Methyl Orange.

Thin cupric oxide (Cu2O) nanobelts with width of few tens of nanometers to few hundreds of nanometers were fabricated in anhydrous ethanol on nanoporous copper templates that was prepared via dealloying amorphous Ti40Cu60 ribbons in hydrofluoric acid solutions at 348 K. The Cu2O octahedral particles preferentially form in the water, and nanobelts readily undergo the growth along the lengthwise and widthwise in the anhydrous ethanol. The ethanol molecules serve as stabilizing or capping reagents, and play a key role of the formation of two-dimensional Cu2O nanobelts. Cu atoms at weak sites (i.e., twin boundary) on the nanoporous Cu ligaments are ionized to form Cu2+ cations, and then react with OH− to form Cu2O and H2O. The two-dimensional growth of Cu2O nanostructure is preferred in anhydrous ethanol due to the suppression of random growth of Cu2O nanoarchitectures by ethanol. Cu2O nanobelts have superior photodegradation performance of methyl orange, three times higher than nanoporous Cu.

Effect of template, reaction time and platinum concentration in the synthesis of PtCu/CNT catalyst for PEMFC applications

Ultra-low PtCu loading on carbon nanotubes (CNT) catalysts were synthesized by a novel galvanic displacement (GD) method under sonication conditions. The influence of the type of copper template, reaction time, and Pt concentration in the galvanic displacement bath and their correlation to electrocatalytic activity of the catalysts for oxygen reduction reaction in acidic media were studied. Among the catalysts synthesized, the best catalyst identified through electrochemical analysis was used to prepare Membrane Electrode Assembly and evaluated in a hydrogen fuel cell. The maximum power density of the PtCu/CNT and commercial catalyst (20% Pt/C) in the fuel cell were 452 mW cm−2 at 0.424 V and 358 mW cm−2 at 0.475 V, respectively, clearly showing the superior electrocatalytic capability of the PtCu/CNT catalyst synthesized in this study when compared with the commercial catalyst.

Copper Template Design for the Synthesis of Bimetallic Copper–Rhodium Nanoshells through Galvanic Replacement

AbstractGalvanic replacement reactions are widely used in the synthesis of bimetallic nanoshells. Essential to these syntheses is the design of template materials with electrochemical potentials that are low enough to facilitate the replacement of a wide variety of metals. While Cu is an attractive template from this standpoint, it has only rarely been used due to its propensity for oxidation and the associated difficulties in achieving chemically stable colloids. Here, a synthetic scheme is demonstrated for the design of supported Cu templates and their subsequent replacement with Rh where the detrimental influences of oxidation are not only mitigated but used to place shape and compositional controls on the reaction product. It is shown that the CuRh nanoshells can be produced that are shaped as substrate‐truncated nanocubes or cuboctahedrons depending upon the degree of exposure that the Cu templates have to dissolved oxygen. Moreover, it is demonstrated that the intentional surface oxidation of the Cu template followed by Cu2O removal results in galvanic replacement reactions yielding porous nanoshells with far greater Rh replacement. The study forwards the design of Cu templates for galvanic replacement reactions and presents opportunities for their use in other template‐mediated syntheses.

Ethanol-Mediated 2D Growth of Cu₂O Nanoarchitectures on Nanoporous Cu Templates in Anhydrous Ethanol.

Two types of cupric oxide (Cu2O) nanoarchitectures (nanobelts and nanopetal networks) have been achieved via immersion nanoporous copper (NPC) templates in anhydrous ethanol. NPC templates with different defect densities have been prepared by dealloying amorphous Ti60Cu40 ribbons in a mixture solution of hydrofluoric acid and polyvinylpyrrolidone (PVP) with different ratios of HF/PVP. Both a water molecule reactant acting as OH− reservoir and the ethanol molecule serving as stabilizing or capping reagent for inhibiting the random growth of Cu2Oplayed a role of the formation of 2-dimensional Cu2O nanoarchitectures. Cu2O nanobelts are preferred to form in anhydrous ethanol on the NPC templates from Ti60Cu40 ribbons dealloying in the solution with low HF concentration and small addition of PVP; and Cu2O nanopetals are tended to grow in anhydrous ethanol from the NPC templates from Ti60Cu40 ribbons dealloying in the solution with high HF concentration and large addition of PVP. With increasing the immersion time in anhydrous ethanol, Cu2O nanopetals united together to create porous networks about 300 nm in thickness. The defect sites (i.e., twin boundary) on nanoporous Cu ligaments preferentially served as nucleation sites for Cu2O nanocrystals, and the higher defect density leads to the formation of uniform Cu2O layer. Synergistic effect of initial microstructure of NPC templates and stabilizing agent of ethanol molecule results in different Cu2O nanoarchitectures.

Fabrication of gold-coated PDMS surfaces with arrayed triangular micro/nanopyramids for use as SERS substrates.

Using the tip-based continuous indentation process, arrays of three-dimensional pyramidal cavities have been successfully machined on a copper template and the structures were successfully transferred to a polydimethylsiloxane (PDMS) surface using a reverse nanoimprinting approach. The structured PDMS surface is coated with a thin Au film, and the final substrate is demonstrated as a surface-enhanced Raman spectroscopy (SERS) substrate. Rhodamine 6G (R6G) was used as a probe molecule in the present study to confirm the SERS measurements. Arrays of micro/nanostructures of different dimensions were formed by the overlap of pyramidal cavities with different adjacent distances using the tip-based continuous indentation process. The effects of the reverse nanoimprinting process and coating process on the final topography of the structures are studied. The experimental results show that the Raman intensity of the Au-film-coated PDMS substrate is influenced by the topography of the micro/nanostructures and by the thickness of the Au film. The Raman intensity of 1362 cm−1 R6G peak on the structured Au-film-coated PDMS substrate is about 8 times higher than the SERS tests on a commercial substrate (Q-SERS). A SERS enhancement factor ranging from 7.5 × 105 to 6 × 106 was achieved using the structured Au-film-coated PDMS surface, and it was demonstrated that the method proposed in this paper is reliable, replicable, homogeneous and low-cost for the fabrication of SERS substrates.

Direct growth of 2D and 3D graphene nano-structures over large glass substrates by tuning a sacrificial Cu-template layer

We demonstrate direct growth of two-dimensional (2D) and three-dimensional (3D) graphene structures on glass substrates. By starting from catalytic copper nanoparticles of different densities and using chemical vapour deposition (CVD) techniques, different 2D and 3D morphologies can be obtained, including graphene sponge-like, nano-ball and conformal graphene structures. More important, we show that the initial copper template can be completely removed via sublimation during CVD and, if need be, subsequent metal etching. This allows optical transmissions close to the bare substrate, which, combined with electrical conductivity make the proposed technique very attractive for creating graphene with high surface to volume ratio for a wide variety of applications, including antiglare display screens, solar cells, light-emitting diodes, gas and biological plasmonic sensors.

Synthesizing a Trefoil Knotted Block Copolymer via Ring-Expansion Strategy

A synthetic trefoil knotted poly(e-caprolatone)-block-poly(l-lactide) (TK-PLA-b-PCL) is synthesized via a ring-expansion strategy from a trefoil knotted tin (Sn) initiator. Ring-closing reaction between the bis-copper(I) templated phenanthroline complex and dibutyldimethoxytin results in a templated trefoil knotted initiator. The bis-copper(I) templated trefoil knotted poly(l-lactide) (TK-PLA) can be synthesized by ring-opening polymerization of l-lactide monomer, and decomplexation reaction of the templated TK-PLA will result in a geniune TK-PLA without constraint from the copper template. Subsequent insertion of e-caprolactone in the bis-copper(I) templated TK-PLA forms the templated trefoil knotted block copolymer, i.e., TK-PLA-b-PCL, and the copper-free TK-PLA-b-PCL can be obtained by decomplexation reaction. Both TK-PLA and TK-PLA-b-PCL are analyzed by the 1H NMR, FT-IR, UV–vis, DLS, and GPC.