Intercalation Of Cu Research Articles

Thermal stability of the CuZrSe2

The CuZrSe2 compound was synthesized for the first time by intercalation of Cu into the ZrSe2 lattice at room temperature. Experimental study of the thermal stability of CuZrSe2 has been performed by in-situ temperature-dependent synchrotron radiation X-ray diffraction (SR-XRPD). CuZrSe2 has a layered structure with space group P3‾m1. The copper atoms at room temperature in the interlayer space are octa- and tetrahedrally coordinated by selenium. Heating leads the decomposition of the main layered phase into binary copper chalcogenides and zirconium trichalcogenide as previously shown for CuxZrTe2. With the increase in temperature the octahedral sites in main layered phase become empty, copper atoms occupy the tetrahedral sites only. Thus, the high-temperature form of CuZrSe2 has a delafossite-like structure.

One-pot preparation of poly(triazine imide) with intercalation of Cu ions: A heterogeneous catalyst for peroxymonosulfate activation to degradate organic pollutants under sunlight

• One-pot preparation of poly(triazine imide) with intercalation of Cu + ions. • The catalyst was efficient in the activation of peroxymonosulfate. • The catalyst demonstrated a wide pH application range and excellent stability. • Possible formation mechanism of the catalyst and degradation pathways of pollutants were studied. A novel poly(triazine imide) (PTI)with intercalation of Cu ion heterogeneous catalysts (Cu/PTI) was synthesized by one-pot thermal condensation of melamine and copper acetate as precursors, resulting in a material with stoichiometry of C 6 N 8.7 Cu. The microscopic morphology and structural characteristics of Cu/PTI were characterized by XRD, SEM, TEM, FT-IR, and XPS. The characterization results corroborated the highly condensed triazine-based structure, and copper mainly existed in the form of Cu + . The possible formation mechanism of composite materials was proposed. The prepared composite Cu/PTI catalyst was used to activate PMS to enhance the simulated pollutant RhB degradation under sunlight irradiation. The experimental results show that sunlight could improve the activation efficiency of Cu/PTI to PMS, Cu/PTI(1:4) had the best activation ability, and the degradation rate of RhB reached 96.2% in 60 min, nearly doubling that without sunlight. Critical impacting factors, initial solution pH was investigated in terms of the catalytic efficiency. The catalyst has a high ability to activate PMS to degrade pollutants in the range of pH = 3–10. In addition, quencher experiments demonstrated that O 2 · - , 1 O 2 , h V B + , and S O 4 · - are the main active species, and a detailed catalytic mechanism was proposed. Thus, the enhanced reactivity of the Cu/PTI catalyst was attributed to the existence of dual catalytic sites and the synergistic effect between Cu and PTI. This strategy provides a feasible way to treat wastewater using Cu/PTI with PMS under sunlight.

Solvothermal and mechanochemical intercalation of Cu into La2O2S2 enabled by the redox reactivity of (S2)2- pairs.

Intercalation of Cu into layered polychalcogenide La2O2S2 was demonstrated to be viable both under solvothermal conditions at 200 °C and mechanical ball milling at ambient temperature. This result evidences the soft-chemical nature of metal intercalation into layered polychalcogenides driven by the redox reactivity of anion-anion bonds.

Spontaneous self-intercalation of copper atoms into transition metal dichalcogenides.

Intercalated transition metal dichalcogenides (TMDs) have attracted substantial interest due to their exciting electronic properties. Here, we report a unique approach where copper (Cu) atoms from bulk Cu solid intercalate spontaneously into van der Waals (vdW) gaps of group IV and V layered TMDs at room temperature and atmospheric pressure. This distinctive phenomenon is used to develop a strategy to synthesize Cu species-intercalated layered TMD compounds. A series of Cu-intercalated 2H-NbS2 compounds were obtained with homogeneous distribution of Cu intercalates in the form of monovalent Cu (I), occupying the tetrahedral sites coordinated by S atoms within the interlayer space of NbS2. The Fermi level of NbS2 shifts up because of the intercalation of Cu, resulting in the improvement of electrical conductivity in the z-direction. On the other hand, intercalation of Cu into vdW gaps of NbS2 systematically suppresses the superconducting transition temperature (T c) and superconducting volume fraction.

Zero Cu valence and superconductivity in high-quality CuxBi2Se3 crystal

In this work, the role of Cu dopants in the development of superconductivity in $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ is investigated. A series of $\mathrm{C}{\mathrm{u}}_{x}\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ ($x=0--0.3$) crystals is grown using the Bridgman method and electrochemical techniques. Based on the observable lattice increases along the $c$ axis, the existence of Cu atoms intercalated in the van der Waals (vdW) gaps in $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ is verified by x-ray diffraction, scanning electron microsopy--energy dispersive spectroscopy, and transmission electron microscopy analysis. Furthermore, the chemical state of the Cu is found to be zero valence by characterization of the x-ray photoelectron and Auger electron spectra. The absence of $\mathrm{C}{\mathrm{u}}^{1+}$ and $\mathrm{C}{\mathrm{u}}^{2+}$ in the electron energy-loss spectroscopy near-edge fine structure is confirmed as well. Meanwhile, our Raman data also show the same result: the intercalation of Cu in the vdW gap which weakens the binding of the quintuple layers in the $\mathrm{C}{\mathrm{u}}_{0.1}\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ crystal. The electric resistance and magnetic susceptibility show a superconducting transition near 3--3.4 K in the series of Cu-doped $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$. A sharp superconducting transition with the highest value of ${T}_{C}=3.4\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and the largest magnetic shielding fraction of 84% is observed in the optimized 10% Cu-doped $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$. These results imply that the formation of superconducting quasiparticles is not related to the charge transfer of Cu, but is supported by the internal stress of Cu intercalated in the van der Waals gap. The superconducting transition observed in the specific heat implies that the superconductivity in $\mathrm{C}{\mathrm{u}}_{x}\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ is unconventional.

A planar and uncharged copper(II)-picolinic acid chelate: Its intercalation to duplex DNA by experimental and theoretical studies and electrochemical sensing application

Using an external redox-active molecule as a DNA hybridization indicator is still a popular strategy in electrochemical DNA biosensors because it is label-free and the multi-site binding can enhance the response signal. A planar and uncharged transition metal complex, Cu(PA)2 (PA = picolinic acid) with excellent electrochemical activity has been synthesized and its interaction with double-stranded DNA (dsDNA) is studied by experimental electrochemical methods and theoretical molecular docking technology. The experimental results reveal that the copper complex interacts with dsDNA via specific intercalation, which is verified by the molecular docking result. The surface-based voltammetric analysis demonstrates that the planar Cu(PA)2 can effectively accumulate within the electrode-confined hybridized duplex DNA rather than the single-stranded probe DNA. Based on this phenomenon, the Cu(PA)2 is utilized as an electrochemical hybridization indicator for the detection of oligonucleotides. The sensing assays show that upon incubation in Cu(PA)2 solution, the probe electrode does not display any Faraday signal, but the hybridized one has a pair of strong redox peaks corresponding to the electrochemistry of Cu(PA)2, showing excellent hybridization indicating function of Cu(PA)2 without background interference. The signal intensity of Cu(PA)2 is dependent on the concentrations of the target oligonucleotide ranging from 1 fM to 100 nM with an experimental detection limit of 1.0 fM. Due to the specific intercalation of Cu(PA)2 with dsDNA, the biosensor also exhibits good ability to recognize oligonucleotide with different base mismatching degree.

Cation Exchange Mediated Synthesis and Tuning of Bimodal Plasmon in Alloyed Ternary Cu3BiS3–xSex Nanorods

We report a robust methodology for synthesizing monodisperse alloyed Bi2S3–xSex nanorods (NRs) to tune optical properties with the variation of Se concentration. The intercalation of Cu(I) into the presynthetic Bi2S3–xSex NRs converted to ternary Cu3BiS3–xSex NRs via cation exchange process. The transformation was monitored through the formation of core/shell Bi2S3–xSex/Cu3BiS3–xSex nanorod heterostructures. Shape anisotropy results in near-infrared bimodal localized surface plasmon resonance (LSPR) in Cu3BiS3–xSex nanorod over a broad range from 600 to 3500 nm with increase of Se:S ratio. The LSPR sensitivity, defined as the change in the LSPR peak wavelength per unit change in the refractive index (RI) of the medium, was estimated to be 250–350 nm/RI unit, much higher than other copper chalcogenides like Cu2S/Cu2Se. A fast photodetector was fabricated by Cu3BiS3–xSex NRs with high photocurrent gain value (∼125) with Se alloying. The intrinsic Cu vacancies and the effective mass of charge carriers play i...

S-Shaped Suppression of the Superconducting Transition Temperature in Cu-Intercalated NbSe2

2H-NbSe2 is the prototype and most frequently studied of the well-known transition metal dichalcogenide (TMDC) superconductors. As 2H-NbSe2 is widely acknowledged as a conventional superconductor, its transition temperature to the superconducting state (Tc) is 7.3 K, a Tc that is substantially higher than those seen for the majority of TMDCs, where Tc values between 2 and 4 K are the norm. Here we report the intercalation of Cu into 2H-NbSe2 to make CuxNbSe2. As is typically found when chemically altering an optimal superconductor, Tc decreases with an increase in x, but the way that Tc is suppressed in this case is unusual: an S-shaped character is observed, with an inflection point near x = 0.03 and, at higher x values, a leveling off of the Tc near 3 K, down to the usual value for a layered TMDC. Electronic characterization reveals corresponding S-like behavior for many of the parameters of the materials that influence Tc. To illustrate its character, the superconducting phase diagram for CuxNbSe2 is c...

Effect of electron injection in copper-contacted graphene nanoribbons

For practical electronic device applications of graphene nanoribbons (GNRs), it is essential to have abrupt and well-defined contacts between the ribbon and the adjacent metal lead. By analogy with graphene, these contacts can induce electron or hole doping, which may significantly affect the I/V characteristics of the device. Cu is among the most popular metals of choice for contact materials. In this study, we investigate the effect of in situ intercalation of Cu on the electronic structure of atomically precise, spatially aligned armchair GNRs of width N = 7 (7-AGNRs) fabricated via a bottom-up method on the Au(788) surface. Scanning tunneling microscopy data reveal that the complete intercalation of about one monolayer of Cu under 7-AGNRs can be facilitated by gentle annealing of the sample at 80 °C. Angle-resolved photoemission spectroscopy (ARPES) data clearly reflect the one-dimensional character of the 7-AGNR band dispersion before and after intercalation. Moreover, ARPES and core-level photoemission results show that intercalation of Cu leads to significant electron injection into the nanoribbons, which causes a pronounced downshift of the valence and conduction bands of the GNR with respect to the Fermi energy (ΔE ~ 0.5 eV). As demonstrated by ARPES and X-ray absorption spectroscopy measurements, the effect of Cu intercalation is restricted to n-doping only, without considerable modification of the band structure of the GNRs. Post-annealing of the 7-AGNRs/Cu/Au(788) system at 200 °C activates the diffusion of Cu into Au and the formation of a Cu-rich surface Au layer. Alloying of intercalated Cu leads to the recovery of the initial position of GNR-related bands with respect to the Fermi energy (EF), thus, proving the tunability of the induced n-doping. [Figure not available: see fulltext.] (Less)

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.

Observation of Localized Vibrational Modes of Graphene Nanodomes by Inelastic Atom Scattering.

Inelastic helium atom scattering (HAS) is suitable to determine low-energy (few meV) vibrations spatially localized on structures in the nanometer range. This is illustrated for the nanodomes that appear often on graphene (Gr) epitaxially grown on single crystal metal surfaces. The nature of the inelastic losses observed in Gr/Ru(0001) and Gr/Cu/Ru(0001) has been clarified by intercalation of Cu below the Gr monolayer, which decouples the Gr layer from the Ru substrate and changes substantially the out-of-plane, flexural phonon dispersion of epitaxial Gr, while maintaining the nanodomes and their localized vibrations. He diffraction proves that the Cu-intercalated Gr layer is well ordered structurally, while scanning tunneling microscopy reveals the persistence of the (slightly modified) periodic array of Gr nanodomes. A simple model explains the order of magnitude of the energy losses associated with the Gr nanodomes and their size dependence. The dispersionless, low-energy phonon branches may radically alter the transport of heat in intercalated Gr.

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.

Evolution of CuI/Graphene/Ni(111) System during Vacuum Annealing

We present a combined core-level spectroscopy and low-energy electron diffraction study of the evolution of thin CuI layers on graphene/Ni(111) during annealing. It has been found that the annealing of the CuI/graphene/Ni(111) system up to 160 °C results in the formation of an ordered CuI overlayer with a (√3 × √3) R30° structure on top of the graphene surface. At annealing temperatures of about 180 °C or higher, the CuI overlayer decomposes with a simultaneous intercalation of Cu and I atoms underneath the graphene monolayer on Ni(111). Nearly complete intercalation of graphene by Cu and I atoms can be achieved by deposition of about 20 Å of CuI, followed by annealing at 200 °C. The intercalated graphene layer is p-doped due to interfacial iodine atoms.

Doping effects on the thermoelectric properties of Cu-intercalated Bi2Te2.7Se0.3

We herein report an enhancement of the thermoelectric performance of spark plasma sintered polycrystalline n-type Bi2Te2.7Se0.3 by the intercalation of Cu and the doping of Al on Bi-sites. Through the intercalation of a small amount of Cu (0.008), the reproducibility could be significantly improved, with ZT was enhanced from 0.64 to 0.73 at 300 K due to the reduced lattice thermal conductivity benefiting from intensified point-defect phonon scattering. We also found that Al is an effective doping element for power factor enhancement and for reducing the lattice thermal conductivity of Cu-intercalated Bi2Te2.7Se0.3. With these synergetic effects, an enhanced ZT values of 0.78 at 300 K and 0.81 at 360 K were obtained in 1 at% Al-doped Cu0.008Bi2Te2.7Se0.3 (Cu0.008Bi1.98Al0.02Te2.7Se0.3).

Nanoscale patterning of a self-assembled monolayer by modification of the molecule-substrate bond.

The intercalation of Cu at the interface of a self-assembled monolayer (SAM) and a Au(111)/mica substrate by underpotential deposition (UPD) is studied as a means of high resolution patterning. A SAM of 2-(4'-methylbiphenyl-4-yl)ethanethiol (BP2) prepared in a structural phase that renders the Au substrate completely passive against Cu-UPD, is patterned by modification with the tip of a scanning tunneling microscope. The tip-induced defects act as nucleation sites for Cu-UPD. The lateral diffusion of the metal at the SAM–substrate interface and, thus, the pattern dimensions are controlled by the deposition time. Patterning down to the sub-20 nm range is demonstrated. The difference in strength between the S–Au and S–Cu bond is harnessed to develop the latent Cu-UPD image into a patterned binary SAM. Demonstrated by the exchange of BP2 by adamantanethiol (AdSH) this is accomplished by a sequence of reductive desorption of BP2 in Cu free areas followed by adsorption of AdSH. The appearance of Au adatom islands upon the thiol exchange suggests that the interfacial structures of BP2 and AdSH SAMs are different.

Induced spin–orbit splitting in graphene: the role of atomic number of the intercalated metal and π–d hybridization

This paper reports spin-dependent valence-band dispersions of graphene synthesized on Ni(111) and subsequently intercalated with monolayers of Au, Cu and Bi. We have previously shown that after intercalation of graphene with Au the dispersion of the π band remains linear in the region of the point of the surface Brillouin zone even though the system exhibits a noticeable hybridization between π states of graphene and d states of Au. We have also demonstrated a giant spin–orbit splitting of π states in Au-intercalated graphene which can reach up to ∼100 meV. In this paper we probe in detail dispersions of graphene π–Au d hybridized bands. We show that intercalation of Cu does not produce a noticeable spin–orbit splitting in graphene although this system, similarly to Au-intercalated graphene, also reveals hybridization between graphene states and d states of Cu. To clarify the role of intercalated Au, the electronic and spin structures of Au monolayers on Ni(111) are comparatively studied with and without graphene on top and the importance of the spin splitting of the d states of the intercalated material is established. These Au d states in graphene/Au/Ni(111) are further studied in detail by spin- and angle-resolved photoemission, and spin-dependent hybridization between graphene and Au bands is revealed. In contrast, intercalation of the sp metal Bi, despite its high atomic number, does not lead to any measurable spin–orbit splitting of the π states of graphene. This means that for the creation of large spin–orbit splitting in graphene, neither hybridization with d states (as with Cu) nor the high atomic number of the intercalated material alone (as with Bi) is sufficient, and a combination of them is required (as with Au).

Preparation of Cu–Al layered double hydroxide intercalated with ethylenediaminetetraacetate by coprecipitation and its uptake of rare earth ions from aqueous solution

A Cu–Al layered double hydroxide intercalated with ethylenediaminetetraacetate (edta•Cu–Al LDH) was prepared by the dropwise addition of a Cu–Al nitrate solution to an edta solution at constant pH values of 8.0, 9.0, and 10.0. The edta•Cu–Al LDH had Hedta3− in the interlayer. Furthermore, the preparation at pH 8.0 resulted in the intercalation of Cu(edta)2−. The edta•Cu–Al LDH was found to take up rare earth ions from aqueous solution. The uptake of Sc3+ and Y3+ by edta•Cu–Al LDH was attributed to both the chelating functions of the edta ion in the interlayer and the chemical properties of Cu–Al LDH itself. The uptake of La3+ by edta•Cu–Al LDH was primarily caused by the chelating function of edta ions in the interlayer. The edta ions in the edta•Cu–Al LDH interlayer formed chelate complexes in the order Sc3+ > Y3+ > La3+ due to their relative stabilities, Sc(edta)− > Y(edta)− > La(edta)−. Thus, edta ions retain their chelating function even when intercalated in a Cu–Al LDH interlayer.

Hybrid Magnetic Multilayers by Intercalation of Cu(II) Phthalocyanine in LDH Hosts

The intrinsic flexibility of layered double hydroxides (LDHs) has been here exploited to design hybrid multilayered materials by intercalation of the copper phthalocyaninetetrasulfonate (CuPcTs) complex in the interlamellar space offered by these layered hosts through a simple anion-exchange procedure. Taking advantage of their chemical versatility, two different LDHs, the diamagnetic ZnAl and the ferromagnetic NiAl, have been synthesized and characterized to explore the differences in the magnetic properties of the hybrids introduced by the intercalation of the paramagnetic complex.

Superconductivity at 5.2 K in ZrTe3 polycrystals and the effect of Cu and Ag intercalation

We report the occurrence of superconductivity in polycrystalline samples of ZrTe3 at temperature 5.2 K at ambient pressure. The superconducting state coexists with the charge density wave (CDW) phase, which sets in at 63 K. The intercalation of Cu or Ag does not have any bearing on the superconducting transition temperature but suppresses the CDW state. The feature of a CDW anomaly in these compounds is clearly seen in the DC magnetization data. Resistivity data are analyzed in order to estimate the relative loss of carriers and reduction in the nested Fermi surface area upon CDW formation in ZrTe3 and the intercalated compounds.

MxTiSe2 (M=Cr, Mn, Cu) electronic structure study by methods of resonance X-ray photoemission spectroscopy and X-ray absorption spectroscopy

Intercalation of Cu and Mn between the layers of TiSe2 leads to the charge transfer from the doped atom to Ti atoms, electronic states of which form the conduction band of TiSe2. This situation drastically differs from another one being observed during intercalation of other transition metals into TiSe2 that leads to the formation of covalent complexes consisting of intercalated atom and nearest neighborhood of the host lattice. Substitution of Ti by Cr in the host lattice positions does not show both charge transfer nor formation of covalent complexes.