Optimization of Parameters of Graphene Synthesis on Copper Foil at Low Methan Pressure

Graphene films on copper foils were synthesized using low-pressure (2200-2800 Pa) chemical vapor deposition (CVD) from methane/hydrogen mixtures. The number of graphene layers is shown to be dependent on the composition of gas mixture and synthesis parameters. The annealing procedure of copper foils used as substrates was optimized to obtain high quality graphene. Atomic and electronic structures of graphene on copper and SiO₂/Si substrates were studied by Raman, X-ray photoelectron, and near-edge X-ray absorption fine structure spectroscopy methods.     

Site-selective direct photochemical deposition of copper on glass substrates using TiO2 nanocrystals

Deposition of copper thin films was achieved by a photocatalytic reaction of site-selectively adsorbed TiO(2) nanocrystals for direct fabrication of copper circuit patterns on glass substrates. The nanocrystal monolayers absorbed on hydrophobic surface templates serve as an effective photocatalyst, producing metallic copper and formic acid via oxidation of methanol in solution. The formic acid generated has also been suggested to serve as an electron donor that accelerates copper deposition through a UV-mediated autocatalytic reaction, even after nanocrystals are embedded into the grown copper films. The thickness of the deposited copper films was easily controlled by varying the UV irradiation time, irradiation power, and initial concentration of methanol as a hole scavenger. The process presented herein provides an effective methodology for resist-free, direct metallization of insulating substrates.     

H-atom abstraction reaction for organic substrates via mononuclear copper(II)-superoxo species as a model for DbetaM and PHM

Hydrogen atom abstraction reactions have been implicated in oxygenation reactions catalyzed by copper monooxygenases such as peptidylglycine alpha-hydroxylating monooxygenase (PHM) and dopamine beta-monooxygenase (DbetaM). We have investigated mononuclear copper(I) and copper(II) complexes with bis[(6-neopentylamino-2-pyridyl)methyl][(2-pyridyl)methyl]amine (BNPA) as functional models for these enzymes. The reaction of [Cu(II)(bnpa)]2+ with H2O2, affords a quasi-stable mononuclear copper(II)-hydroperoxo complex, [Cu(II)(bnpa)(OOH)]+ (4) which is stabilized by hydrophobic interactions and hydrogen bonds in the vicinity of the copper(II) ion. On the other hand, the reaction of [Cu(I)(bnpa)]+ (1) with O2 generates a trans-mu-1,2-peroxo dicopper(II) complex [Cu(II)2(bnpa)2(O2(2-]2+ (2). Interestingly, the same reactions carried out in the presence of exogenous substrates such as TEMPO-H, produce a mononuclear copper(II)-hydroperoxo complex 4. Under these conditions, the H-atom abstraction reaction proceeds via the mononuclear copper(II)-superoxo intermediate [Cu(II)(bnpa)(O2-)]+ (3), as confirmed from indirect observations using a spin trap reagent. Reactions with several substrates having different bond dissociation energies (BDE) indicate that, under our experimental conditions the H-atom abstraction reaction proceeds for substrates with a weak X-H bond (BDE < 72.6 kcal mol(-1)). These investigations indicate that the copper(II)-hydroperoxo complex is a useful tool for elucidation of H-atom abstraction reaction mechanisms for exogenous substrates. The useful functionality of the complex has been achieved via careful control of experimental conditions and the choice of appropriate ligands for the complex.     

高分子希夫碱金属配合物活性中心对催化活化分子氧性能的影响

以交联聚苯乙烯担载酪氨酸希夫碱为配体,制备了其锰、钴、铜高分子金属配合物,分别以环己烯、异丙苯和乙苯为底物,氧气为氧源,研究了温和条件下不同金属中心活化分子氧能力,发现高分子担载铜金属配合物的催化活化分子氧能力最强,对反应机理进行了探讨.     

Atomic-scale characterization of graphene grown on copper (100) single crystals

Growth of graphene on copper (100) single crystals by chemical vapor deposition has been accomplished. The atomic structure of the graphene overlayer was studied using scanning tunneling microscopy. A detailed analysis of moire? superstructures present in the graphene topography reveals that growth occurs in a variety of orientations over the square atomic lattice of the copper surface. Transmission electron microscopy was used to elucidate the crystallinity of the grown graphene. Pristine, defect-free graphene was observed over copper steps, corners, and screw dislocations. Distinct protrusions, known as "flower" structures, were observed on flat terraces, which are attributed to carbon structures that depart from the characteristic honeycomb lattice. Continuous graphene growth also occurs over copper adatoms and atomic vacancies present at the single-crystal surface. The copper atom mobility within vacancy islands covered with suspended graphene sheets reveals a weak graphene-substrate interaction. The observed continuity and room-temperature vacancy motion indicates that copper mobility likely plays a significant role in the mechanism of sheet extension on copper substrates. Lastly, these results suggest that the quality of graphene grown on copper substrates is ultimately limited by nucleation at the surface of the metal catalyst.     

A Facile Method for Preparation of Superhydrophobic Surfaces with Poly(furfuryl Alcohol)/PTFE Composites

A stable superhydrophobic surface have been fabricated with poly(furfuryl alcohol) (PFA)/polytetrafluoroethylene (PTFE) composite coatings on steel substrates by using a facile method. The observation of field emission scanning electron microscopy revealed that the hierarchical microstructures formed on the surfaces are controlled by varying the curing temperature. This method can be easily operated on substrates of steel, therefore is readily developed to other engineering metal substrates such as aluminum, copper, etc.     

Direct Patterning of Copper on Polyimide by Site‐Selective Surface Modification via a Screen‐Printing Process

We demonstrate a simple route to fabricating copper circuit patterns on the surface of polyimide film. The copper pattern can be obtained in three steps: 1) Formation of partially potassium hydroxide modified pattern via a screen‐printing process, 2) formation of macromolecular metal complex with copper, and 3) copper metallization by DMAB reduction. The morphologies of these copper patterns are determined by cross‐sectional transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), and atomic force microscopy (AFM). Furthermore, the growing process of the metallic copper film is investigated. The direct patterning of copper patterns onto polyimide substrates is promising for use in electronics industry as a large‐area and low‐cost processing technique.     

Screen-printed copper ion-selective electrodes

A simple, low-cost and reproducible method for the mass production of potentiometric ion-selective electrodes for copper ions is presented. These planar, strip sensors were obtained by screen-printing. The application of pastes cured at low temperature allows printing of the sensors on low-cost, plastic substrates. The pastes for printing of ion-sensitive thick-film membranes were based on copper (1) and copper (II) sulfides. The analytical characteristics of the thick-film electrodes were compared. The analytical properties (range of determination, sensitivity, selectivity, response time) of the copper (I) sulfide-based sensors were comparable with those for conventional ion-selective electrodes.     

Highly Oriented Pyrolytic Graphite as a Platform for Atomic Absorption Spectrometry

Compared to pyrolytic graphite (PG) and pyrolytically coated polycrystalline graphite (PCPG), which are commonly employed substrates for graphite furnace atomic absorption spectrometry (GFAAS), highly oriented pyrolytic graphite (HOPG) is characterized by a high degree ofc-axis alignment with relatively few active sites and imperfections present on the surface. The usefulness of HOPG and commercial PG platforms for the determination of lead, copper, and aluminum by GFAAS was compared. Qualitative comparison of the absorption profiles and temperature optimizations suggest that lead, copper with a chemical modifier (palladium), and aluminum interact similarly with the two graphite substrates, while copper without a modifier interacts less strongly with HOPG than with PG. These results are in agreement with previous studies that have demonstrated that copper interacts strongly with PG and PCPG. HOPG and PG were employed for the determination of a pine needles standard reference material (SRM) and Fraser fir (Abies fraseri) samples. The analyses of the SRM gave good agreement with the certified value using both substrates, and comparable values were obtained for the samples. These results suggest that HOPG may be useful as a model for PG or PCPG when techniques such as scanning tunneling microscopy that require a high degree ofc-axis alignment are employed.     

Deposition of CuInS2 thin films using copper- and indium/sulfide-containing precursors through a two-stage MOCVD method

Copper indium disulfide (CuInS2; CIS) films were deposited on various substrates by two-stage metal-organic chemical vapor deposition (MOCVD) at relatively mild conditions, using Cu- and In/S-containing precursors without toxic H2S gas: first, a pure Cu thin film was prepared on glass or indium/tin oxide glass substrates by using a single-source precursor, bis(ethylbutyrylacetato)copper(II) or bis(ethylisobutyrylacetato)copper(II); second, on the resulting Cu film, tris(N,N-ethylbutyldithiocarbamato)indium(III) was treated to produce CIS films by a MOCVD method at 430 degrees C. In this process, their thicknesses and stoichiometries were found to be elaborately controlled on demand by adjusting the process conditions. The optical band gap of the stoichiometric CIS film was about 1.41 eV, which is in the near-optimal range for harvesting solar radiation energy.     

分子自组装法制备具有可控浸润性的铜表面简

通过简单浸泡的方法在铜基底上制备出了具有微纳米复合结构的氧化铜,再利用混合硫醇溶液[含HS(CH2)9CH3和 HS(CH2)11OH]对浸泡后的表面进行修饰,通过控制溶液中HS(CH2)11OH的浓度,制备出一系列具有不同浸润性的铜表面,实现表面从超疏水到超亲水的有效调控. 研究发现,表面浸润的可控性源于表面复合结构与不同化学组成的协同作用,微纳米复合结构的存在为表面浸润性的调节提供了必要的条件.     

Screen-printed copper ion-selective electrodes

A simple, low-cost and reproducible method for the mass production of potentiometric ion-selective electrodes for copper ions is presented. These planar, strip sensors were obtained by screen-printing. The application of pastes cured at low temperature allows printing of the sensors on low-cost, plastic substrates. The pastes for printing of ion-sensitive thick-film membranes were based on copper (I) and copper (II) sulfides. The analytical characteristics of the thick-film electrodes were compared. The analytical properties (range of determination, sensitivity, selectivity, response time) of the copper (I) sulfide-based sensors were comparable with those for conventional ion-selective electrodes. Received: 12 January 2000 / Revised: 13 March 2000 / Accepted: 16 March 2000     

Effect of temperature on ring-shaped-deposit formated at evaporation of droplets of silver-nanoparticle dispersions

The effect of temperature is studied on the geometric parameters and conductivity of ring-shaped deposits formed at evaporation of droplets of dispersions of silver nanoparticles on hydrophilic (glass) and hydrophobic (copper) substrates. It has been shown that increasing temperature leads to substantial changes in the deposit profile. Therewith, the effects of temperature on droplet evaporation on glass and copper substrates are different. It has been found that the lateral conductivity of a ring-shaped deposit formed on a glass substrate increases stepwise similarly to a percolation transition at a droplet-evaporation temperature of 58°C. It has been suggested that the reason for the temperature effect is related to a change in the ratio between the rates of physicochemical processes occurring at different stages of droplet evaporation.     

Copper(II) carboxylate promoted intramolecular diamination of terminal alkenes: improved reaction conditions and expanded substrate scope

The copper(II) carboxylate promoted diamination reaction has been improved by the use of the organic soluble copper(II) neodecanoate [Cu(ND)2]. Cu(ND)2 allowed the less-polar solvent dichloroethane (DCE) to be used, and as a consequence, decomposition of less-reactive substrates could be avoided. High diastereoselectivity was observed in the synthesis of 2,5-disubstituted pyrrolidines. Ureas, bis(anilines), and alpha-amido pyrroles derived from 2-allylaniline could also participate in the diamination reaction.     

Atom probe tomography characterization of thin copper layers on aluminum deposited by galvanic displacement

″Ultrathin″ metallization layers on the order of nanometers in thickness are increasingly used in semiconductor interconnects and other nanostructures. Aqueous deposition methods are attractive methods to produce such layers due to their low cost, but formation of ultrathin layers has proven challenging, particularly on oxide-coated substrates. This work focused on the formation of thin copper layers on aluminum, by galvanic displacement from alkaline aqueous solutions. Analysis by atom probe tomography (APT) showed that continuous copper films of approximately 1 nm thickness were formed, apparently the first demonstration of deposition of ultrathin metal layers on oxidized substrates from aqueous solutions. The APT reconstructions indicate that deposited copper replaced a portion of the surface oxide film on aluminum. The results are consistent with mechanisms in which surface hydride species on aluminum mediate deposition, either by directly reducing cupric ions or by inducing electronic conduction in the oxide, thus enabling cupric ion reduction by Al metal.     

Novel Electroless Deposition of Cu<Subscript>3</Subscript>Se<Subscript>2</Subscript> Film on Silicon Substrate by a Simple Galvanic Displacement Process

A novel electroless deposition method for depositing highly uniform adhesive thin films of copper selenide (Cu₃Se₂) on silicon substrates from aqueous solutions is described. The deposition is carried out by two coupled galvanic reactions in a single deposition bath containing copper cations, hydrogen fluoride, and selenous acid: the galvanic deposition of copper on silicon and the subsequent galvanic reaction between the deposited copper with selenous acid in the deposition bath. The powder X-ray diffraction and scanning electron microscopy are used to characterize and examine the deposited films.     

Electrochemical performance of catalyst couples M/stainless steel 430 (M: Ni,Co, and Cu) for the hydrogen production in KOH electrolyte

Journal of Solid State Electrochemistry - In this work, three catalysts (nickel, cobalt, copper) are electrochemically deposited on stainless steel substrates AISI 430 and their performances as...     

Adhesion characteristics of aromatic thermosetting copolyester and glass fiber laminates with copper foils for improved circuit boards

Copper foils are the vital elements used in microelectronic devices. Adequate adhesion between copper foils to various substrates, such as Si, SiO₂ and polyimide, is crucial to functional electronic devices. Liquid‐crystalline polymers (LCPs) can be used as substrates for these modules as well as the adhesive to copper foils. The adhesion between aromatic thermosetting copolyester (ATSP)/fiberglass fabric (GF) laminates and copper foils was characterized by peel strength tests. It was found that ATSP/GF laminates with copper foil using ATSP oligomers as adhesive showed a highest average peel strength of 711 N · m^?1. Scanning electron microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) showed an excellent bond between the composite and the copper foil interface. Failure occurred between the backside of the copper foil and the ATSP/GF laminates in the peeling test and the mechanism is discussed. Thermogravimetic analyzer (TGA) indicated a thermal stability up to 371°C for ATSP/GF composite substrate and a glass transition temperature of over 400°C as determined by peak in tan δ during Dynamic Mechanical Analysis (DMA). Copyright © 2016 John Wiley & Sons, Ltd.     

Evaporation of droplets of silver nanoparticle dispersions on metal surfaces

The formation of ring-shaped deposits during the evaporation of droplets of silver nanoparticle dispersions on aluminum, copper, and nickel substrates has been studied, and the geometric characteristics and conductivity of the deposits have been determined. The formation process of the deposits on the above substrates has been shown to exhibit some peculiarities to compare with that on hydrophilic glass substrates. These peculiarities lead to substantial differences in the geometric parameters and structure of the deposits formed on substrates of different natures. Therewith, the qualitative regularities of variations in the geometric parameters and conductivity of the deposits with the size (numerical concentration) of silver nanoparticles remain preserved.     

分子自组装法制备具有可控浸润性的铜表面

通过简单浸泡的方法在铜基底上制备出了具有微纳米复合结构的氧化铜, 再利用混合硫醇溶液[含HS(CH₂)₉CH₃和 HS(CH₂)₁₁OH]对浸泡后的表面进行修饰, 通过控制溶液中HS(CH₂)₁₁OH的浓度, 制备出一系列具有不同浸润性的铜表面, 实现表面从超疏水到超亲水的有效调控. 研究发现, 表面浸润的可控性源于表面复合结构与不同化学组成的协同作用, 微纳米复合结构的存在为表面浸润性的调节提供了必要的条件.