Deposition Of Metallic Copper Research Articles

Copper(II)-Tannic Acid@Cu with In Situ Grown Gold Nanoparticles as a Bifunctional Matrix for Facile Construction of Label-Free and Ultrasensitive Electrochemical cTnI Immunosensor.

Sensitive detection of cardiac troponin I (cTnI) is of great significance in the diagnosis of a fatal acute myocardial infarction. A redox-active nanocomposite of copper(II)-tannic acid@Cu (CuTA@Cu) was herein prepared on the surface of a glassy carbon electrode by electrochemical deposition of metallic copper combined with a metal stripping strategy. Then, HAuCl4 was in situ reduced to gold nanoparticles (AuNPs) by strong reductive catechol groups in the TA ligand. The AuNPs/CuTA@Cu composite was further utilized as a bifunctional matrix for the immobilization of the cTnI antibody (anti-cTnI), producing an electrochemical immunosensor. Electrochemical tests show that the immunoreaction between anti-cTnI and target cTnI can cause a significant reduction of the electrochemical signal of CuTA@Cu. It can be attributed to the insulating characteristic of the immunocomplex and its barrier effect to the electrolyte ion diffusion. From the signal changes of CuTA@Cu, cTnI can be analyzed in a wide range from 10 fg mL-1 to 10 ng mL-1, with an ultralow detection limit of 0.65 fg mL-1. The spiked recovery assays show that the immunosensor is reliable for cTnI determination in human serum samples, demonstrating its promising application in the early clinical diagnosis of myocardial infarction.

Influence of chemistry and topography on the wettability of copper

To understand the complex interplay of topography and surface chemistry in wetting, fundamental studies investigating both parameters are needed. Due to the sensitivity of wetting to miniscule changes in one of the parameters it is imperative to precisely control the experimental approach. A profound understanding of their influence on wetting facilitates a tailored design of surfaces with unique functionality.We present a multi-step study: The influence of surface chemistry is analyzed by determining the adsorption of volatile carbonous species (A) and by sputter deposition of metallic copper and copper oxides on flat copper substrates (B). A precise surface topography is created by laser processing. Isotropic topography is created by ps laser processing (C), and hierarchical anisotropic line patterns are produced by direct laser interference patterning (DLIP) with different pulse durations (D).Our results reveal that the long-term wetting response of polished copper surfaces stabilizes with time despite ongoing accumulation of hydrocarbons and is dominated by this adsorption layer over the oxide state of the substrate (Cu, CuO, Cu2O). The surfaces’ wetting response can be precisely tuned by tailoring the topography via laser processing. The sub-pattern morphology of primary line-like patterns showed great impact on the static contact angle, wetting anisotropy, and water adhesion. An increased roughness inside the pattern valleys combined with a minor roughness on pattern peaks favors air-inclusions, isotropic hydrophobicity, and low water adhesion. Increasing depth of the primary topography can also induce air-inclusions despite increasing peak roughness while time dependent wetting transitions were observed.

Electrode fabrication at liquid interfaces: Towards transparency and flexibility

We demonstrate here the huge potential of liquid/liquid interfaces to process different kinds of materials as thin films, aiming for the preparation and modification of electrodes, specifically focusing on transparent and flexible ones. As a proof-of-concept, we prepared single-walled carbon nanotubes films at water/chloroform interfaces and deposited over ordinary poly(ethylene terephthalate) (PET) substrates, yielding stable, robust, transparent, and flexible electrodes. The transmittance and the conductivity of the electrodes were controlled by tuning simple experimental parameters, illustrating the broadness of the method. The electrochemical performance of the electrodes was evaluated towards ferro/ferricyanide redox pair, and their real application in a classical electrochemical deposition of metallic copper. Afterwards, the potentiality of the liquid/liquid interfacial route to modify electrodes was demonstrated by depositing a thin and transparent film of polyaniline, in which the electrochromic properties were displayed. Finally, the construction and performance of symmetric, transparent, and flexible supercapacitor devices based on the polyaniline-modified electrodes were presented.

Synthesis and characterization of Cu-BaTiO3 nanocomposite for atrazine remediation under visible-light radiation from wastewater

The most herbicide used in agriculture in many regions is atrazine, which leads to many worries as reported by its toxicity. In this, we have synthesized BaTiO3 nanoparticles through a simple method, its absorption was converted from UV region to visible region via deposition of metallic copper using a photoassisted deposition way. The results of characterizations declared the act of Cu for enhancing the optoelectronic, optical, and structural properties of barium titanite photocatalyst. The bandgap of barium titanite photocatalyst can be controlled via controlling the weight percent of metallic copper. The outcomes declared 5 wt % of copper can reduce bandgap of BaTiO3 to 2.77 eV from 3.28 eV. The Cu@ BaTiO3 nanoparticles showed an exceptional atrazine photodegradation in the water at 1.6 gL–1 within 40 min with outstanding recyclability. The improvement of the photocatalytic activity of the prepared Cu@ BaTiO3 is specified to the local surface plasmon resonance(LSPR) of cupper-barium titanite photocatalyst. This diminishes the recombination rate of electron-hole and productively exceeds the undoped BaTiO3 photocatalyst.

Electrochemical synthesis and photoelectrochemical characterization of copper hexacyanoferrate (II) deposited on n-Si(1 0 0)

In this study, we examined the synthesis and characterization of copper hexacyanoferrate (II) on an n-Si(100) substrate. The copper hexacyanoferrate (II) was formed in the following stages: (i) deposition of metallic copper on an n-Si(100) electrode using an electroless process and (ii) electrooxidation of the copper film in a solution containing Fe(CN)64− ions. In the first stage, a study using a potential step method was performed, and the corresponding nucleation and growth mechanisms were determined. A morphologic analysis of the deposits obtained at different potentials was performed using atomic force microscopy. The results were consistent with a 3D progressive nucleation with diffusion-controlled growth. Electrochemical characterization under illumination demonstrated a charge transfer process due to the photogenerated holes in the valence band of silicon. Afterwards, the diffusion coefficient of the potassium ions and rate constants of the electrochemical processes were determined. Finally, this research is designed to increase the understanding of this system for its possible use in an electrochemical storage device that can be loaded in situ via the photovoltaic action of the doped silicon.

In Situ Electron Energy-Loss Spectroscopy in Liquids

In situ scanning transmission electron microscopy (STEM) through liquids is a promising approach for exploring biological and materials processes. However, options for in situ chemical identification are limited: X-ray analysis is precluded because the liquid cell holder shadows the detector and electron energy-loss spectroscopy (EELS) is degraded by multiple scattering events in thick layers. Here, we explore the limits of EELS in the study of chemical reactions in their native environments in real time and on the nanometer scale. The determination of the local electron density, optical gap, and thickness of the liquid layer by valence EELS is demonstrated. By comparing theoretical and experimental plasmon energies, we find that liquids appear to follow the free-electron model that has been previously established for solids. Signals at energies below the optical gap and plasmon energy of the liquid provide a high signal-to-background ratio regime as demonstrated for LiFePO4 in an aqueous solution. The potential for the use of valence EELS to understand in situ STEM reactions is demonstrated for beam-induced deposition of metallic copper: as copper clusters grow, EELS develops low-loss peaks corresponding to metallic copper. From these techniques, in situ imaging and valence EELS offer insights into the local electronic structure of nanoparticles and chemical reactions.

Preparation of Diamine‐β‐diketiminato Copper(II) Complexes and Their Application in the Reverse Atom‐Transfer Radical Polymerization of Styrene

AbstractCompound Et2NCH2CH2N=C(Me)CH=C(Me)NHCH2CH2NEt2 (HL), after conversion to the Li+ salt with use of MeLi, reacts with CuCl2 in toluene to yield CuClL (1). The compound adopts a four‐coordinate CuClN3 environment with a pendant amino arm. The same reaction with CuCl and[Cu(MeCN)4]BF4 leads to disproportionation with deposition of metallic copper. Crystals of compounds [CuL][CuCl2] (2) and [CuL]BF4 (3) were isolated in minor amounts from these reactions. The [CuL]+ ion in these compounds has a four‐coordinate CuN4 environment. Compound 2 was also obtained in good yields from the reaction between equivalent amounts of 1 and CuCl. Compound 1 was used to control the radical polymerization of styrene under ARGET ATRP conditions in the presence of glucose as reducing agent and bromoethylbenzene as initiator. The polymerization behavior indicates that the controlling ability of this system is negatively affected by its slow trapping rate and by the disproportionation of the CuL catalyst.

A Simulation Model of Resistive Switching in Electrochemical Metallization Memory Cells (ECM)

AbstractThe storage principal of the Electrochemical Metallization Memory Cell is based on change of cell resistance induced by electro-chemical driven growth and rupture of a cupric or silver filament in an insulating matrix. This kind of switching was found in several materials as AgGeSe, CuGeS, silicon oxide or tungsten oxide [1].During write operation copper or silver is oxidized at the corresponding electrode and copper or silver ions are driven out of the copper or silver anode into the insulating matrix due to the applied field, whereas the insulating matrix serves as solid electrolyte. The silver or copper ions migrate towards the cathode. At the cathode electrochemical reduction occurs, and deposition of metallic copper or silver takes place. Fast diffusion paths in the solid electrolyte matrix or preferred nucleation sites (seeds) at the boundary lead to filamentary growth. This growing cupric or silver dendrite finally reaches the anode and switches the device to a low resistance state.Based on this switching mechanism a FEM simulation model was set up. To simplify the model space charges due to silver or copper migration are neglected. It is further assumed, that the conductivity in the solid electrolyte is only ionic. Hence, it is sufficient to solve the well-known Laplace equation to address the electric properties as well as ion migration. A “Level Set” method is used to track the boundary of the growing filament. The velocity of this boundary is proportional to the ionic current density calculated by Laplace equation. Based on this model simulations are applied to cell structures with multiple fast diffusion paths and seeds. Simulation results show that just one filament reaches the anode.In a second step, Butler-Vollmer boundary conditions are introduced. This nonlinearity leads to an exponential dependence between switching time and switching voltage. As switching voltage increases, switching time decreases.A simulation model capable of simulating ECM memory cells is presented. The model enables to simulate the behaviour of different cell geometries or different materials as solid electrolyte. Furthermore it gives deeper insight into the switching mechanism.This work was supported by the European project EMMA “Emerging Materials for Mass storage Architectures” (FP6-033751).

Effect of Heavy Metals on Dechlorination of Carbon Tetrachloride by Iron Nanoparticles

Effects of heavy metals on the dechlorination of carbon tetrachloride by iron nanoparticles were investigated in terms of reaction kinetics and product distribution using batch systems. Removal of heavy metals and the interaction between heavy metals and iron nanoparticles at the iron surface were also examined. It was found that Cu(II) enhanced the carbon tetrachloride dechlorination by iron nanoparticles and led to produce more benign products (i.e., CH4). Pb(II) may increase reduction rate slightly but also increase the production of more toxic intermediates such as dichloromethane. In comparison to the iron reduction system without heavy metals, effects of As(V) were negligible while Cr(VI) decreased the dechlorination rate by a factor of 2. Removal of As(V) by iron nanoparticles behaved pseudo-first-order reaction kinetics but a fast initial removal followed by a slow subsequent process was found in the cases of Cu(II) and Pb(II). Scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis indicated the deposition of heavy metals onto the iron surface. X-ray diffraction (XRD) analysis showed Cu(II) was reduced to metallic copper and cuprite (Cu2O) at the iron surface while no reduced lead species was observed from the Pb(II)-treated iron nanoparticles. Limited data suggested an oxidized lead species formed. The enhanced dechlorination by Cu(II) can be attributed to the deposition of metallic copper and cuprite at the iron surface. This study suggests that implementation of iron nanoparticles rather than engineered bimetallic iron nanoparticles for remediation of mixed contamination with both chlorinated organics and heavy metals is sufficient.

Effect of Photochemical and Reductive Activation of Titanium Dioxide on Its Catalytic Properties in Deposition of Metallic Copper

We have established that as a result of both photochemical and reduction heat treatment of titanium dioxide preparations impregnated with transition metal salts, there is an increase in their catalytic efficiency in the process of copper deposition. We consider reactions leading to activation and deactivation of the catalysts.

Effect of Transition Element Ions on the Catalytic Activity of Titanium Dioxide during Chemical Deposition of Metallic Copper

We have established the high catalytic activity of TiO2, modified by Pd2+, Cu2+, Fe3+, and Co2+ ions, in reduction of Cu2+ ions by formaldehyde in solution. We propose a likely scheme for the electronic processes that occur, including injection of electrons from the reducing agent into the conduction band and formation of metallic nanoparticles on the surface that effectively catalyze deposition of metallic copper.

Synergistic Effects of Benzotriazole and Copper Ions on the Electrochemical Impedance Spectroscopy and Corrosion Behavior of Iron in Sulfuric Acid

Benzotriazole (BTAH) and copper ions exhibit synergistic effects on the electrochemical impedance spectroscopy and corrosion behavior of iron in sulfuric acid. The presence of submicro- and micromolar amounts of Cu2+ ions along with millimolar amounts of BTAH caused order of magnitude increases in the polarization resistance of the iron/acid interface, above those caused by either BTAH or Cu2+ ions (which is equivalent to order of magnitude decreases in the corrosion rate). This was accompanied by a significant decrease in the capacity of the electrical double layer of the interface, which also showed synergistic effects. The results are interpreted in terms of the deposition, on the iron surface, of a protective film composed of a polymeric complex formed from copper ions and adsorbed BTAH that is believed to be of the form [Cu(I)BTA]n. This film inhibits the cathodic partial (hydrogen evolution) reaction, which is the rate-determining step (rds) and hence the overall corrosion reaction. An increase in the concentration of either Cu2+ or BTAH enhances this synergistic effect. However, there is a critical concentration of copper ions (5 × 10-6 M) beyond which further increase decreases the magnitude of the synergistic effect. This is attributed to deposition of metallic copper on the iron surface at higher concentrations of Cu2+ ions, which promotes the rds and hence the overall corrosion reaction. The results are supported by measurements of polarization curves and mass loss under various conditions.

Selective Deposition of Thin Copper Films onto Silicon with Improved Adhesion

Metallization plays a key role in the production process of integrated devices. Recently, copper (Cu) has been proposed as an alternative material to aluminum to address the need for metallic thin films with low resistivity and high electromigration resistance. 1 As a consequence, great attention has been paid to electrochemical processes, which enable the deposition of metallic copper at low temperatures with low costs. Copper electroless deposition has been shown to selectively plate silicon (Si) substrates and structures with high aspect ratios and large structural heights. 2,3 However, this method requires a pretreatment to activate the surface. Selectivity is achieved only to the extent that the activating treatment can be made selectively. In addition, many studies have also been carried out on the galvanic deposition of copper from fluoride containing solutions.4-11 In contrast to electroless deposition, galvanic displacement deposition requires no prior activation of the surface and is truly selective to silicon surfaces. Thus, it provides an attractive deposition method for copper interconnects or seed layers for subsequent metallization.4 Galvanic displacement is also a promising avenue for the integration of metals in micromechanical devices, due to its conformal nature and high substrate selectivity. Despite these attractive features, a crucial issue in the aforementioned processes is the lack of adhesion of copper to the Si substrate, which may severely constrain their application. 12 In particular, copper films deposited by galvanic displacement fail the qualitative Scotch tape test. In this paper, we report a process for the galvanic deposition of copper onto silicon from fluoride-containing solutions. Thin copper films with reflective and smooth surfaces and excellent adhesion to silicon are obtained. Results on plating of microelectromechanical systems (MEMS) after release are also presented. Polycrystalline silicon and single crystalline Si(100) and Si(111), p- or n-type, and analytical grade chemicals were used. Samples were ultrasonicated in acetone and, after drying with nitrogen flux, etched in concentrated hydrofluoric acid for 10 min. The hydrogenterminated surfaces thus obtained were rinsed, dried, and immersed in the plating solution. The following additives were used to prepare the aqueous solution: ammonium fluoride (NH 4 F 40%) 50 vol %, copper sulfate (CuSO 4 ·5H 2 O) 0.01 M, ascorbic acid (C 6 H 8 O 6 ) 0.01 M, sodium potassium tartrate (KNaC 4 H 4 O 6 ·4H 2 O) 0.005 M, and methanol 30 vol % (percentages are referred to the final solution volume).13 The pH of the solution was 7.5. Room temperature (25°C) and gentle agitation of samples were used. Samples were finally rinsed in deionized water and dried with nitrogen flux. The adhesion of the copper film to the substrate is strongly related to the presence of ascorbic acid in solution. The absence of the acid results in the formation of a copper film which fails the standard scotch tape test. Because we have observed a similar effect when ascorbic acid was substituted with fumaric acid, and both acids are

Nucleation of Trace Copper on the H−Si(111) Surface in Aqueous Fluoride Solutions

The initial nucleation process of trace amounts of copper metal on the H−Si(111)(1 × 1) surface in aqueous fluoride solution was investigated by ex-situ scanning tunneling microscopy. We observed that copper nucleates preferentially along step edges and appears to inhibit the step-flow etching of silicon. The presence of copper species in the fluoride solution also appears to inhibit the formation of terrace etch pits, which are known to be initiated by dissolved oxygen. It is suggested that silicon−dihydroxyl−cuprous ion complexes are formed at dihydroxyl kink sites, resulting in the preferential nucleation of Cu metal at step edges and the inhibition of step-flow etching. Copper ions in solution may act as catalysts for the disproportionation and electrocatalytic reduction of superoxide anion radical formed by the electrochemical reduction of dissolved oxygen at the silicon surface. Such reactions would reduce the rate of etch-pit initiation and may also decrease the rate of deposition of metallic copper on the silicon surface.

Synthesis, spectroscopic, photophysical and electrochemical properties of cyano-bridged copper(I)–ruthenium(II) complexes

Complexes of the formula [(N–N)Cu(AsPh3)CN] (N–N=2,2′–bipyridine, 1,10–phenanthroline) have been synthesized. Ru(bpy)2Cl2.2H2O and [(η5–cp)Ru(PPh3)2Cl] react with [(N–N)Cu(AsPh3)CN] to give cyano-bridged compounds. IR spectral studies in the low frequency region (700–50 cm−1) and 4000–400 cm−1 region reveal cyano bridging in the complexes. Luminescence measurements suggest oxidation of metal centres (CuI–CuII and RuII–RuIII) on excitation at a charge transfer band. This has been substantiated with electrochemical studies of complexes which exhibit quasi-reversible reductions viz. RuIII⧹RuII and CuII⧹CuI. The deposition of metallic copper is also observed at a potential of −1.55 V. Based on these data, a mechanism for photo-redox reaction of complexes has been presented. The properties of these bimetallic complexes are compared with those of parent complexes.

Preparation of Cu Thin Films by the Decomposition of Copper Acetylacetonate on Catalytically Active Substrate Surfaces

Abstract A selective CVD system used to deposit the central metal of a volatile complex preferentially on catalytically active substrate surfaces was examined. Copper(II) acetylacetonate was vaporized in a flow of hydrogen and decomposed on Ni, Pd, and Al plates in order to deposit metallic copper. When a Ni plate was used as the substrate, deposition of metallic copper occurred at temperatures in the range 13O–180 °C only on the substrate surfaces. The formation of an ultrathin film of Cu of uniform thickness was confirmed. On a Pd substrate, the formation of an ultrathin Cu film of uniform thickness was also observed. On an Al substrate, however, deposition occurred nonselectively at temperatures above 160 °C, not only on the substrate surface, itself, but also on the wall of the glass tube as well as the quartz wool surrounding the Al plate. In addition, the formation of fine particles of Cu, instead of thin film, was found to exist on the substrate. Because the deposition of Cu took place on catalytically active surfaces selectively, the deposition was considered to proceed by a catalytic hydrogenation of the C=O bond of the ligand, thus detaching it from the Cu ion and allowing it to decompose the complex and deposit Cu metal.

Pitting Corrosion Behaviour of Aluminium in Water Desalination Plants

The pitting corrosion of aluminium in water containing pitting corrosion agents and metal cations at moderately high temperatures has been investigated by electrochemical and surface analysis methods. Heat pretreatment ameliorated the resistance to pitting corrosion and overcame the aggressive effect of Cl −. This is attributed to the thickening of the protective film and change of its composition into more stable oxides as shown by Auger depth profiling and X-ray diffraction, respectively. Such modifications would shield the points susceptible to pitting initiation and/or suppress the kinetics of the partial cathodic reaction. The severe pitting corrosion suffered by aluminium in presence of Cu 2+ decreased by heat treatment. The induced film modification hinders the deposition of metallic copper by displacement on aluminium surface and, therefore, inhibits the galvanic coupling. In Cd 2+ solutions, where the mixed oxide CdO·6Al 2O 3 was detected on aluminium surface, film modification was not obtained.

Study of oxidation-reduction reactions of triethylgermyl derivatives of vanadocene by EPR method

The EPR (The Electron Proton Resonance) method was used in the present paper to study the oxidation reactions of bis-(cyclopentadienyl)triethylgermylvanadium (I) by cupric chloride and some chloro-containing d/sup 1/ complexes of Cp/sub 2/V. The oxidation of (I) by anhydrous CuCl/sub 2/ in tetrahydrofuran or toluene leads to the appearance of an EPR spectrum with g/sub i/ = 1.9956, A/sub i//sup 51//sup V/ = 66.8 Oe. The simultaneous deposition of metallic copper as a mirror is also observed when a 2:1 ratio of the reactants is used.

Two New Carbonyls: Copper and Tellurium

WE are able to report the isolation of copper carbonyl, which we obtained from the reaction of carbon monoxide with heated cuprous oxide. It is a white, readily sublimable solid, the vapour of which is dissociated at a higher temperature with the consequent deposition of metallic copper. Only small quantities are formed, but enough has been collected to afford a preliminary analysis indicating Cu(CO)3 as the empirical formula. A polymeric form would be expected in the case of copper, and its properties suggest that it is very possibly dimeric.