Copper Intercalation Research Articles

Ultralow Loading Copper-Intercalated MoO3 Nanobelts with High Activity against Antibiotic-Resistant Bacteria.

In recent years, the infection rate of antibiotic resistance has been increasing year by year, and the prevalence of super bacteria has posed a great threat to human health. Therefore, there is an urgent need to find new antibiotic alternatives with long-term inhibitory activity against a broad spectrum of bacteria and microorganisms in order to avoid the proliferation of more multidrug-resistant (MDR) bacteria. The presence of natural van der Waals (vdW) gaps in layered materials allows them to be easily inserted by different guest species, providing an attractive strategy for optimizing their physicochemical properties and applications. Here, we have successfully constructed a copper-intercalated α-MoO3 nanobelt based on nanoenzymes, which is antibacterial through the synergistic effect of multiple enzymes. Compared with α-MoO3, MoO3-x/Cu nanobelts with a copper loading capacity of 2.11% possess enhanced peroxidase (POD) catalytic activity and glutathione (GSH) depletion, indicating that copper intercalation significantly improves the catalytic performance of the nanoenzymes. The MoO3-x/Cu nanobelts are effective in inducing POD and oxidase (OXD) and catalase (CAT) activities in the presence of H2O2 and O2, which resulted in the generation of large amounts of reactive oxygen species (ROS), which were effective in bacterial killing. Interestingly, MoO3-x/Cu nanobelts can serve as glutathione oxidase (GSHOx)-like nanoenzymes, which can deplete GSH in bacteria and thus significantly improve the bactericidal effect. The multienzyme-catalyzed synergistic antimicrobial strategy shows excellent antimicrobial efficiency against β-lactamase-producing Escherichia coli (ESBL-E. coli) and methicillin-resistant Staphylococcus aureus (MRSA). MoO3-x/Cu exhibits excellent spectral bactericidal properties at very low concentrations (20 μg mL-1). Our work highlights the wide range of antibacterial and anti-infective biological applications of copper-intercalated MoO3-x/Cu nanobelt catalysts.

Building an Efficient Optoelectronic Property at the AZO/Cu/AZO Heterogeneous Interface with Copper Intercalation

Building an Efficient Optoelectronic Property at the AZO/Cu/AZO Heterogeneous Interface with Copper Intercalation

Photocatalytic activity in nanostructured zinc oxide thin films doped with metallic copper

Nanostructured zinc oxide (ZnO) thin films doped with metallic copper were synthesized by a sputtering process. As the copper sputtering power increased from 20 to 40 W, the copper content increased from 2.37% to 14.15%. The film thickness increased from 166 nm (ZnO) to 387 nm (14.15Cu–ZnO). The crystallite size on plane (002) of ZnO films was 7.95 nm and increased to 17.82 nm at 14.15 Cu–ZnO films. Spherical particles were observed, and the surface roughness increased from 2.77 nm (ZnO) to 5.35 nm (14.15 Cu–ZnO). The intercalation of metallic copper in the ZnO lattice decreased the optical transmittance and photoluminescence (PL) intensities and shifted the absorption edge towards higher photon wavelengths. Methyl green dye (MG) was used as a pollutant in wastewater to examine the photocatalytic activity of the films. The degradation ratio of MG dye in ZnO thin films was 60%, reaching 99.8% at 14.15 Cu–ZnO thin films.

Preparation of dyeing, flame retardant and anti-dripping polyethylene terephthalate fibers based on natural sodium copper chlorophyll dyeing and intercalation of phosphorylated sucrose fatty acid ester

As the largest synthetic fibers in the world, polyethylene terephthalate (PET) fibers have a wide range of applications. However, PET fibers are flammable fibers with serious droplet phenomenon during combustion, which has great potential safety hazards. To solve the issue, multifunctional PET fibers with dyeing, flame retardant and anti-dripping were developed in this work. First, dyed PET fibers (DY-PET) were prepared by directly dyeing of PET fibers with sodium copper chlorophyllin (SCC). Then, DY-PET was intercalated with ammonium phosphate of sucrose fatty acid ester (APSFA) to obtain the flame retardant PET fibers (FR-PET). Compared with the original samples, the peak heat release rate (PHRR) and total heat release rate (THR) of DY-PET and FR-PET were significantly reduced. Meanwhile, the limiting oxygen index (LOI) of DY-PET and FR-PET was also improved, indicating the improved flame retardant properties of DY-PET and FR-PET. In addition, the anti-dripping performance was excellent, which was mainly due to the high temperature self-crosslinking, high temperature ionic aggregation and hydrogen bond & π-π stacking effect. The improved flame retardant performance of FR-PET was attributed to the blocking effect of the generated char layer catalyzed by APSFA under high temperature and the dilution effect of incombustible gas resulting from the thermal decomposition of APSFA. This work provided a scalable strategy for the design of dyeing, flame retardant and anti-dripping PET fibers, and endowed PET with great potential application in the field of functional polymer materials.

Link between superconductivity and a Lifshitz transition in intercalated Bi2Se3

Topological superconductivity is an exotic phase of matter in which the fully gapped superconducting bulk hosts gapless Majorana surface states protected by topology. Intercalation of copper, strontium or niobium between the quintuple layers of the topological insulator Bi$_2$Se$_3$ increases the carrier density and leads to superconductivity that is suggested to be topological. Here we study the electronic structure of strontium-intercalated Bi$_2$Se$_3$ using angle resolved photoemission spectroscopy (ARPES) and Shubnikov-de Haas (SdH) oscillations. Despite the apparent low Hall number of $\sim2 \times 10 ^{19}$cm$^{-3}$, we show that the Fermi surface is shaped as an open cylinder with a larger carrier density of $\sim 10 ^{20}$cm$^{-3}$. We suggest that superconductivity in intercalated Bi$_2$Se$_3$ emerges with the appearance of a quasi-2D open Fermi surface.

Enhancing Light-Matter Interactions in MoS2 by Copper Intercalation.

The intercalation of layered compounds opens up a vast space of new host-guest hybrids, providing new routes for tuning the properties of materials. Here, it is shown that uniform and continuous layers of copper can be intercalated within the van der Waals gap of bulk MoS2 resulting in a unique Cu-MoS2 hybrid. The new Cu-MoS2 hybrid, which remains semiconducting, possesses a unique plasmon resonance at an energy of ≈1eV, giving rise to enhanced optoelectronic activity. Compared with high-performance MoS2 photodetectors, copper-enhanced devices are superior in their spectral response, which extends into the infrared, and also in their total responsivity, which exceeds 104 A W-1 . The Cu-MoS2 hybrids hold promise for supplanting current night-vision technology with compact, advanced multicolor night vision.

Novel Copper Nanoparticles Intercalated Polyurethane Heparin/Poly-L-Lysine Chelates Coated Stents: Viability Study for Coronary Vascular Cells and Aneurysms Treatments.

Continuous delayed endothelium regeneration and continues thrombosis development designate a task for coronary artery stent rehabilitation. To progress the direct vascular cell behavior, aneurysms treatments and compatibility of cardiovascular implants novel copper intercalated polyurethane heparin/poly-L-lysine chelates treated stent has established in this report. The functional group modifications, structural characteristics, and stability of the chelates have investigated for polyurethane heparin: poly-L-lysine, copper intercalated polyurethane heparin/poly-L-lysine coated stents. The FTIR results showed the copper intercalation at 446 cmr and the Cu 2s peak at 932 eV from XPS also indicated that the successful coating of copper, polyurethane heparin, poly-L-lysine. The relative surface geomorphology of the chelates displayed the uniform Cu coating consisting of multilayer poly-L-lysine on the substrate. The stability and biocompatibility studies indicated the significantly enhanced performance with clot the APTT and TT periods as clotting and cell proliferation assessments. This type of composite proposes a stage on a stent external area for discerning track of vascular cell performance and aneurysms treatments with low side effects.

Chemically Switchable n-Type and p-Type Conduction in Bismuth Selenide Nanoribbons for Thermoelectric Energy Harvesting.

Realizing switchable n-type and p-type conduction in bismuth selenide (Bi2Se3), a traditional thermoelectric material and a topological insulator, is highly beneficial for the development of thermoelectric devices and also of great interest for spintronics and quantum computing. In this work, switching between n-type and p-type conduction in single Bi2Se3 nanoribbons is achieved by a reversible copper (Cu) intercalation method. Density functional theory calculations reveal that such a switchable behavior arises from the electronic band structure distortion caused by the high-concentration Cu intercalation and the Cu substitution for Bi sites in the host lattice. A proof-of-concept in-plane thermoelectric generator is fabricated with one pair of the pristine n-type and intercalated p-type Bi2Se3 nanoribbons on a microfabricated device, which gives rise to an open-circuit voltage of 4.8 mV and a maximum output power of 0.3 nW under a temperature difference of 29.2 K. This work demonstrates switchable n-type and p-type electrical conduction in Bi2Se3 nanoribbons via a facile chemical approach and the practical application of nanoribbons in a thermoelectric device.

Copper(II) complex intercalated graphene oxide nanocomposites as versatile, reusable catalysts for click reaction

In this work, we report the efficient, high stable copper(II) complexes intercalated graphene oxide (GO) used as green catalysts for copper(II) complex mediated click reaction. Copper(II) Bis(2,2′‐bipyridine) [CuII (bpy)2] (C1) and Copper(II) Bis(1,10‐phenanthroline) [CuII (phen)2] (C2) have synthesized for the intercalation of corresponding nanocomposites with GO, [GO@CuII (bpy)2] (GO‐C1) and [GO@CuII (phen)2] (GO‐C2). The noncovalent interaction of complexes supported on the surface of the GO nanosheets proves as an evident active site to facilitate the enhanced catalytic activity of copper‐catalyzed alkyne azide cycloaddition (CuIIAAC) reaction for the isolation of 1,4‐disubstituted‐1,2,3‐triazoles as click products in shorter reaction time with 80%–91% yield (five examples). The X‐ray diffraction (XRD) pattern of these composites shows the enhanced interlayers d‐spacing range of 1.01–1.12 nm due to the intercalation of copper(II) complexes in between the GO basal planes and characterized by X‐ray photoelectron spectroscopy (XPS), Fourier‐transform infrared spectroscopy (FT‐IR), Raman, UV, scanning electron microscope (SEM), and thermogravimetric analysis (TGA). The as‐prepared nanocomposites were employed for the typical click reactions using the substrates of azide and acetylene. These classes of composite materials can be referred to recyclable, heterogeneous, green catalysts with high atom economy and could also be used for the isolation of click products in biomolecules.

In Situ Dynamics during Heating of Copper-Intercalated Bismuth Telluride

Summary The presence of a van der Waals gap within layered materials enables the intercalation of guest species, which can be used for tuning properties. The introduction of intercalant species may also lead to structural transformations across a range of temperatures and use conditions, but we have a limited understanding of the high-temperature evolution of intercalated layered materials. Here, we use in situ transmission electron microscopy to investigate temperature-dependent structural evolution of Bi2Te3, a layered material with well-known application as a thermoelectric, which contains intercalated Cu. As temperature is increased, the initially disordered Cu undergoes local ordering within the van der Waals gap, along with anisotropic sublimation behavior of the crystals. As the temperature is raised further, layered Cu2Te crystals nucleate and grow with a crystallographic relationship to the Bi2Te3 lattice. Notably, the presence of Cu decreases the thermal stability of the Bi2Te3 and substantially alters the transformation pathways during heating.

Tuning thermal conductivity of bismuth selenide nanoribbons by reversible copper intercalation

Actively tuning thermal transport properties of materials at nanoscale is of great interest in many applications. In this work, we demonstrated reversible copper (Cu) intercalation on individual bismuth selenide (Bi2Se3) nanoribbons and investigated the effects of intercalation/de-intercalation of Cu atoms on their thermal transport properties. Distinct from prior studies that have shown reduced thermal conductivity (κtot) after intercalation, a crossover in κtot was observed over the measured temperature range in this work, i.e., κtot is significantly suppressed at low temperatures but enhanced above 250 K by Cu intercalation. This intriguing crossover phenomenon is attributed to the interplay between the enhanced electronic thermal conductivity (κe) and the reduced lattice thermal conductivity (κph), both of which result from the intercalated Cu atoms. Moreover, we showed that thermal conductivity could be further tuned by the de-intercalation of Cu atoms. Compared to the pristine nanoribbon, a dramatically lower in-plane κph was observed for intercalated and de-intercalated nanoribbons due to the formation of the Cu/Bi2Se3 superlattice structure. Theoretical modeling revealed that the reduced κph was primarily owing to the enhancement of phonon boundary scattering and point defect scattering. This work provides a facile approach to tune thermal transport properties at nanoscale, which can be potentially used in thermal switch and thermoelectric applications.

Emergent superconductivity upon disordering a charge density wave ground state

We explore the interplay of a charge density wave (CDW) order and s-wave superconductivity (sSC) in a disordered system. Recent experiments on 1T-TiSe_2, where the pristine sample has a commensurate CDW order and the superconductivity appears upon copper intercalation, motivates our study. Starting with an extended Hubbard model, with parameters which yield a CDW ground state within Hartree-Fock-Bogoliubov formalism in pure systems, we show that the addition of disorder quickly wipes out the global charge order by disrupting periodic modulation of density at some (low) strength of disorder. Along with this, the subdominant superconducting order emerges in regions that spatially anti-correlates with islands of strong local CDW order. The short-range density modulations, however, continue to persist and show discernible effects up to a larger disorder strength. The local CDW puddles reduce in size with increasing disorder and they finally lose their relevance in effecting the properties of the system. Our results have strong implications for the experimental phase diagram of transition metal dichalcogenides.

Thermal stability of the layered modification of Cu0.5ZrTe2 in the temperature range 25–900 °C

The thermal stability of the layered modification of the Cu0.5ZrTe2 polycrystalline intercalation compound, synthesized at room temperature, has been studied in the temperature range 25-900 °C. A change in the occupation of the octahedral and tetrahedral coordinated sites in the interlayer space of the zirconium ditelluride was observed using in-situ time-resolved synchrotron X-ray powder diffraction experiments. The formation of the rhombohedral CuZr2Te4 phase, which is stable in the temperature range 300-700 °C, has been observed. The copper intercalation at room temperature leads to the formation of a phase in which the Cu atoms occupy only octahedral sites in the interlayer space. At temperatures above the decay temperature of the rhombohedral CuZr2Te4, a layered phase with Cu atoms uniformly distributed between octahedral and tetrahedral sites in the interlayer space is stable. The changes in the crystal structure independent of temperature are in agreement with the previously proposed model, according to which the stability of the layered or the rhombohedral phase is determined by the entropy factor associated with the distribution of the intercalated atoms between the octahedral and tetrahedral sites in the interlayer space.

Electrochemical studies of copper-doping processes in layered crystals of the family [(Ge,Sn,Pb)(Te,Se)] m [(Bi,Sb)2(Te,Se)3] n (m, n = 0, 1, 2…)

The processes of copper intercalation into the van der Waals gaps of layered ternary alloys of the family [(Ge,Sn,Pb)(Te,Se)] m [(Bi,Sb)2(Te,Se)3] n (m, n = 0, 1, 2…) to modify the electrical, mechanical, and other physical properties of samples are studied. A proportional decrease in the intercalated copper concentration ΔN Cu with decreasing relative volume density of van der Waals gaps D VdW = s –1 and with increasing package plyness s and package thickness ξ1 under variations in the composition of ternary alloys is revealed.

Evidence for topological behavior in superconducting CuxZrTe2−y

We present structural, magnetic, electrical, thermal transport, Hall coefficient, and pressure-dependent resistivity measurements on $\mathrm{C}{\mathrm{u}}_{x}\mathrm{ZrT}{\mathrm{e}}_{2\ensuremath{-}y}$ compounds with $x=0.05$, 0.1, 0.15, 0.2, and 0.3, and $y$ varied between $0\ensuremath{\le}y\ensuremath{\le}0.8$. In order to calculate the ground state, ab initio calculations of the electronic structure of these materials were performed. Our results show that copper intercalation in $\mathrm{ZrT}{\mathrm{e}}_{2}$ induces superconductivity in the $\mathrm{ZrT}{\mathrm{e}}_{2}$ system. For the $\mathrm{C}{\mathrm{u}}_{0.3}\mathrm{ZrT}{\mathrm{e}}_{1.2}$ sample, Hall and Seebeck coefficient measurements show that the system is predominantly negatively charged with carrier density close to ${10}^{19}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$. The temperature dependence of the Hall coefficient, the Seebeck coefficient, and the lower critical field indicates that this material presents multiband character. Pressure-dependent resistivity vs temperature measurements reveal that while the normal-state resistivity decreases with increasing applied pressure, the superconducting transition temperature is completely insensitive to the applied pressure (for pressure in the range 0--1.3 GPa). This suggests that the Fermi gas is intrinsically degenerate under very high pressure, and therefore does not change much with varying external pressure. Finally the band structure calculation shows a dispersion curve containing a bulk three-dimensional Dirac conelike feature at the L point in the Brillouin zone, which is gapless in the absence of spin-orbit coupling, but develops a gap when this coupling is considered. Altogether, the results indicate that the superconducting compound $\mathrm{C}{\mathrm{u}}_{x}\mathrm{ZrT}{\mathrm{e}}_{2\ensuremath{-}y}$ presents a signature of multiband behavior and may possibly be a new example of a topological superconductor.

First principles investigation of copper and silver intercalated molybdenum disulfide

We characterize the energetics and atomic structures involved in the intercalation of copper and silver into the van der Waals gap of molybdenum disulfide as well as the resulting ionic and electronic transport properties using first-principles density functional theory. The intercalation energy of systems with formula (Cu,Ag)xMoS2 decreases with ion concentration and ranges from 1.2 to 0.8 eV for Cu; Ag exhibits a stronger concentration dependence from 2.2 eV for x = 0.014 to 0.75 eV for x = 1 (using the fcc metal as a reference). Partial atomic charge analysis indicates that approximately half an electron is transferred per metallic ion in the case of Cu at low concentrations and the ionicity decreases only slightly with concentration. In contrast, while Ag is only slightly less ionic than Cu for low concentrations, charge transfer reduces significantly to approximately 0.1 e for x = 1. This difference in ionicity between Cu and Ag correlates with their intercalation energies. Importantly, the predicted values indicate the possibility of electrochemical intercalation of both Cu and Ag into MoS2 and the calculated activation energies associated with ionic transport within the gaps, 0.32 eV for Cu and 0.38 eV for Ag, indicate these materials to be good ionic conductors. Analysis of the electronic structure shows that charge transfer leads to a shift of the Fermi energy into the conduction band resulting in a semiconductor-to-metal transition. Electron transport calculations based on non-equilibrium Green's function show that the low-bias conductance increases with metal concentration and is comparable in the horizontal and vertical transport directions. These properties make metal intercalated transition metal di-chalcogenides potential candidates for several applications including electrochemical metallization cells and contacts in electronics based on 2D materials.

Observation of a Charge Density Wave Incommensuration Near the Superconducting Dome in Cu_{x}TiSe_{2}.

X-ray diffraction was employed to study the evolution of the charge density wave (CDW) in Cu_{x}TiSe_{2} as a function of copper intercalation in order to clarify the relationship between the CDW and superconductivity. The results show a CDW incommensuration arising at an intercalation value coincident with the onset of superconductivity at around x=0.055(5). Additionally, it was found that the charge density wave persists to higher intercalant concentrations than previously assumed, demonstrating that the CDW does not terminate inside the superconducting dome. A charge density wave peak was observed in samples up to x=0.091(6), the highest copper concentration examined in this study. The phase diagram established in this work suggests that charge density wave incommensuration may play a role in the formation of the superconducting state.

Enhanced Superconductivity in Double-Doping Cu0.15TaSe2−x S x

Superconducting Cu x TaSe2(x=0.05, 0.15) and Cu0.15TaSe2−x S x (x=0, 0.5, 1, 1.5) single crystals have been systematically fabricated by a chemical vapor transport method. It is found that the double doping in TaSe2, i.e., the simultaneous intercalation of Cu and substitution of Se by S, can substantially enhance the superconducting transition temperature. Transport property measurements give evidence of the coexistence and competition of charge density wave state and superconductivity in Cu x TaSe2 which provide meaningful information to understand the complex electronic states in this system. The parallel shift and the fan-shape broadening behaviors are observed in the superconducting transition curves under magnetic fields of Cu0.15TaSeS and TaSeS, respectively, indicating an increase of coherence length and suppression of superconducting fluctuation induced by copper intercalation.

Copper-Intercalated Birnessite as a Water Oxidation Catalyst.

We report a synthetic method to increase the catalytic activity of birnessite toward water oxidation by intercalating copper in the interlayer region of the layered manganese oxide. Intercalation of copper, verified by XRD, XPS, ICP, and Raman spectroscopy, was accomplished by exposing a suspension of birnessite to a Cu(+)-bearing precursor molecule that underwent disproportionation in solution to yield Cu(0) and Cu(2+). Electrocatalytic studies showed that the Cu-modified birnessite exhibited an overpotential for water oxidation of ∼490 mV (at 10 mA/cm(2)) and a Tafel slope of 126 mV/decade compared to ∼700 mV (at 10 mA/cm(2)) and 240 mV/decade, respectively, for birnessite without copper. Impedance spectroscopy results suggested that the charge transfer resistivity of the Cu-modified sample was significantly lower than Cu-free birnessite, suggesting that Cu in the interlayer increased the conductivity of birnessite leading to an enhancement of water oxidation kinetics. Density functional theory calculations show that the intercalation of Cu(0) into a layered MnO2 model structure led to a change of the electronic properties of the material from a semiconductor to a metallic-like structure. This conclusion from computation is in general agreement with the aforementioned impedance spectroscopy results. X-ray photoelectron spectroscopy (XPS) showed that Cu(0) coexisted with Cu(2+) in the prepared Cu-modified birnessite. Control experiments using birnessite that was decorated with only Cu(2+) showed a reduction in water oxidation kinetics, further emphasizing the importance of Cu(0) for the increased activity of birnessite. The introduction of Cu(0) into the birnessite structure also increased the stability of the electrocatalyst. At a working current of 2 mA, the Cu-modified birnessite took ∼3 times longer for the overpotential for water oxdiation to increase by 100 mV compared to when Cu was not present in the birnessite.

Tuned thermoelectric properties of TiS1.5Se0.5 through copper intercalation

Polycrystalline samples of copper intercalated CuxTiS1.5Se0.5 (x=0, 0.025, 0.05 and 0.1) are synthesized by classical high temperature reaction. The resulting powders are successfully densified by using spark plasma sintering. As expected, XRD refinements show that Cu intercalation between TiS1.5Se0.5 slabs induces an increase in the c lattice parameter. Electrical resistivity and Seebeck coefficient decrease drastically with increasing Cu content, direct consequence of the increased carrier concentration. In parallel, the lattice thermal conductivity of CuxTiS1.5Se0.5 is significantly reduced compared to unfilled TiS1.5Se0.5. Overall, the dimensionless thermoelectric figure of merit increases with temperature and reaches a maximum value of 0.54 at 700K for Cu0.05TiS1.5Se0.5, the highest value so far observed in layered titanium chalcogenides.