Corrosion Of Cu Research Articles

Corrosion inhibitors in H2O2 system slurry for Ru based barrier layer Cu interconnect chemical mechanical polishing and optimization

Ruthenium (Ru) has the advantages of low resistivity, high thermal stability, and good adhesion and wettability, making it an important solution for breaking through the 14 nm process as a new barrier layer material for multilayer copper interconnect. The purpose of copper (Cu) interconnect Ru-based barrier layer chemical mechanical polishing (CMP) is to obtain a highly flat surface, which not only includes the ideal Ru removal rate and selectivity of the Cu/Ru removal rate, but also inhibition of Cu corrosion. In this article, the corrosion inhibition mechanism of environmentally friendly and highly water-soluble inhibitor 5-methylthio-1 H-tetrazole (MTT) on Cu was studied. The inhibitory effect of MTT on Cu was analyzed through static etching rate testing, electrochemical experiments, and surface characterization. A systematic test was conducted on the planarization performance of the optimized polishing slurry. The corrosion inhibition mechanism of MTT on Cu was revealed through quantum chemical calculations and XPS testing. The experimental results show that the corrosion inhibitor MTT can effectively improve the surface quality of Cu. Quantum chemical calculations and experimental results indicate that MTT can be adsorbed on the surface of Cu through both physical and chemical methods, forming a dense passivation film, thereby inhibiting the corrosion of Cu. The optimized ratio of Ru-based barrier layer CMP polishing slurry was 5 wt% SiO2, 0.15 wt% H2O2, 20 mM ethylenediamine (EDA), 5 mM K4Fe(CN)6, and 2000 ppm MTT, resulted in the Cu/Ru removal rate selectivity of 1:1.18 and the Cu/Ru corrosion potential difference of 3 mV. The average correction values for dishing and erosion on the test pattern wafer of the Ru barrier layer were 355 Å and 280 Å, respectively. The results of this study indicate that MTT is an effective copper corrosion inhibitor in alkaline H2O2-based polishing slurry, providing meaningful references for Ru-based barrier layer copper interconnect CMP.

Corrosion behaviour of aluminum and copper in dimethyl- and diethyl phosphate ionic liquids

The effect of phosphonium—based ionic liquids (ILs): 1,3-dimethyl-imidazolium dimethyl phosphate, [C1C1IM][DMP], 1-ethyl-1-methylpyrrolidinium dimethyl phosphate, [C1C2PYR][DMP], 1-hydroxyethyl-1-methylpyrrolidinium dimethyl phosphate, [C1C2OHPYR][DMP], 1-methylpyridinium dimethyl phosphate, [C1Py][DMP], 1-ethyl-1-methylmorpholinium dimethyl phosphate, [C1C2MOR][DMP], 1-ethyl-1-methylpiperidinium dimethyl phosphate, [C1C2PIP][DMP], N,N,N-trimethyl-N-methylammonium dimethyl phosphate, [N1,2,2,2][DMP], 1-ethyl-3-methylimidazolium diethyl phosphate, [C1C2IM][DEP], 1-ethyl-1-methylpyrrolidinium diethyl phosphate, [C1C2PYR][DEP], 1-ethyl-1-methyl-morpholinium diethyl phosphate, [C1C2MOR][DEP] and tri(butyl)ethylphosphonium diethyl phosphate, [P2,4,4,4][DEP] on the corrosion of aluminium and copper were investigated using potentiodynamic polarization. All tested ionic liquids formed a passivation layer on the surface of the tested metals and due to their low affinity to promote corrosion of Cu and Al, can be used in refrigeration technology.

Accelerated microbiologically influenced corrosion of copper by sulfate‐reducing bacterium Desulfovibrio desulfovibrio

AbstractThe corrosion behavior and electrochemical damage mechanisms induced by sulfate‐reducing bacteria (SRB) on copper (Cu) were investigated in this study. Electrochemical impedance spectroscopy revealed that SRB accelerated the corrosion of Cu, albeit with a mitigating effect observed due to the formation of a protective and dense biofilm. However, upon the rupture of this protective film, the corrosion tendency of Cu significantly increased. Surface analysis corroborated these findings, with the predominant corrosion product identified as Cu2S, a result further supported by thermodynamic calculations. The accelerated corrosion of Cu was primarily attributed to the physiological metabolism of SRB, which generates hydrogen sulfide as the principal agent driving corrosion processes.

Influence of electric field, liquid film thickness, and sodium chloride deposition on atmospheric corrosion of Cu

Printed circuit boards (PCBs) are prone to failure due to the influence of environmental factors such as humidity, salt spray, and electric fields during usage. As the lead pitch of PCBs decreases and these environmental factors become challenging to control, corrosion becomes unavoidable. This study used a self-built thin liquid film–electric field coupling environment in an in situ electrochemical testing apparatus. PCB-Cu electrodes were evaluated using open-circuit potential and polarization curve tests on the thin liquid film. This study systematically investigated the effects of external electric field bias, sodium chloride deposition, and liquid film thickness on PCB-Cu corrosion. The results showed that increased bias promoted Cu corrosion in the coupled environment and altered electrode reactions. The cathodic process transitioned from activation control at 0–1 V to hydrogen evolution electrochemical control at 3 V for electrode reactions. Increased sodium chloride deposition enhanced the Cu corrosion rate in the coupled environment primarily due to Cl− damaging the corrosion product film. Under different liquid film thickness conditions, the corrosion rates can be ranked as 200 μm > 300 μm > 100 μm, with 200 μm exhibiting the highest corrosion rate and marking the transition point from the cathodic to anodic control of the corrosion reactions. Orthogonal analysis results indicated that bias was the most influential factor affecting Cu corrosion, followed by liquid film thickness and sodium chloride deposition.

Investigating the Influence of Pre-Grown Copper Oxide Film on Sulfide-Induced Corrosion of Copper

Used nuclear fuel should be confined safely and permanently due to its detrimental effect on human health and the environment. The universally proposed plan for the permanent disposal of used nuclear fuels is to bury the containers containing the nuclear used fuels in a multi-barrier system known as a deep geological repository (DGR) at a depth 500 m underground. The container is the key engineered barrier that can withstand long-term mechanical loads and the corrosive environment. The proposed container in some countries will be designed with either a cylindrical Cu shell containing a nodular cast iron insert (Sweden, Finland) or a Cu‐coated carbon steel vessel (Canada). After emplacement, the container will experience a range of conditions underground, evolving from warm, humid, and oxidizing to cool, dry, and anoxic over time.During the initial oxidizing period, the entrained oxygen, trapped in the DGR upon sealing, and the water-radiolysis will lead to the formation of an oxide/hydroxide film on the Cu container surface. Once anoxic conditions are eventually established, sulfide ions produced by the action of sulfate-reducing bacteria remote from the container will become the main potential oxidant.So far, considerable efforts have been devoted to investigating exclusively either the oxic period or the anoxic period. However, the significant gap that the current research aims to address is how the early period of oxide growth affects the later stages of the repository evolution, at which time the primary threat to the integrity of the Cu container would be sulfide ions within the groundwaters. In this series of experiments, various methods were applied to create different types of copper oxide/hydroxide layers with known compositions and unique structures, to investigate their role in the subsequent sulfide-induced corrosion of the underlying Cu under de-aerated conditions. The morphology of the surface oxide film and the nature and concentration of sulfide species will influence the possible manners in which the sulfide species could interact with the oxide film; for example: Chemical conversion of copper oxide to copper sulfideGalvanically-coupled processes between the copper oxide reduction and Cu oxidation by sulfideDirect corrosion of Cu by sulfide species arriving at the metal surface Our results have shown that regardless of the composition and nature of the oxide film, either a single-phase oxide film or a dual layer of combined copper oxides, the pre-grown oxide film on the Cu surface is partially converted to a copper sulfide film via chemical conversion and/or galvanically-coupled processes. Moreover, an unreacted remnant of the oxide layer was detected on the surface, surviving for longer than the duration of our experiments. This remnant oxide is non-protective, and permits direct corrosion of Cu by sulfide species arriving at the metal surface.Oxide films were grown either electrochemically, radiolytically, or chemically. The electrochemically-grown oxides, upon exposure to sulfide solutions, underwent quick conversion to copper sulfide (Cu2S) as shown by the corrosion potential (Ecorr) measurements and cathodic stripping voltammetry (CSV) at different immersion times. The same results were observed for the radiolytically-grown oxide with a multi-layer structure composed of Cu(I) and Cu(II) oxides. The thickness of the two mentioned oxides was on the nanometre scale.Chemically grown oxides were thicker than the electrochemically- and radiolytically-grown oxides. The results of CSVs showed that some parts of the oxide film and the sulfide film formed on top of the oxide film could not be cathodically stripped from the surface and remained in the form of a defective film, and that direct corrosion of Cu occurred, driven by sulfide species reaching the metal surface. This suggests that conversion of oxide to sulfide films is fastest when an electrochemical pathway is available, and much slower if it must depend on the chemical pathway. The regions of the oxide which were not connected electrically to the surface could only undergo chemical conversion. The results obtained from immersion of copper oxide powder in sulfide solution support the idea that the chemical conversion is not as quick as the electrochemical reaction in the presence of copper metal.

The Influences of Traces of Oxygen and Sulfide on the Corrosion of Copper Under Canadian Nuclear Waste Disposal Conditions

The Canadian repository concept for the permanent disposal of used nuclear fuel is to seal it in Cu-coated steel containers and dispose of it in a deep geological repository (DGR) surrounded by compacted bentonite clay. The Cu coating will be directly bonded on the steel vessel and lid using electro-deposition (ED-Cu), with the final container closure weld sealed with a cold-sprayed Cu deposit (CS-Cu). To assess the durability of such a container, long-term corrosion experiments have been performed on CS-Cu and ED-Cu specimens, and compared with those performed on wrought Cu specimens provided by the Swedish Nuclear Fuel and Waste Management Company (SKB-Cu).Experiments were conducted in 3 M NaCl solutions containing traces of sulfide (< 10- 6 M) for exposure periods of ≥150 days. These conditions reflect a generic groundwater that may influence container corrosion in a Canadian DGR Since conditions in a DGR will evolve from initially oxic to eventually anoxic, experiments were conducted under three sets of redox conditions: (i) aerated (oxic) conditions; (ii) Ar-purged (oxic to anoxic transition conditions (with a dissolved [O2] ~ 10- 6 M)); and (iii) anaerobic chamber (anoxic) conditions ([O2] < 1.3 × 10- 9 M). The exposure process was followed using open circuit (i.e., corrosion) potential and polarization resistance (RP) measurements. Specimens were analyzed before and after corrosion using optical microscopy, scanning electron microscopy on surfaces and focused ion beam cut cross sections, Raman spectroscopy, and X-ray photoelectron/Auger spectroscopy.In all environments, all three types of specimens (ED-Cu, CS-Cu, SKB-Cu) showed similar behaviour. Under anoxic conditions, minor corrosion, indicated by large RP values, leading to the deposition of traces of chalcocite (Cu2S) (identified by Raman spectroscopy) and observed by SEM, indicated that corrosion could be attributed to reaction with the trace amounts of sulfide present in NaCl. In Ar-purged solutions, the RP values were approximately one order of magnitude lower (i.e., the corrosion rate was one order of magnitude higher) than those measured under anoxic conditions, and significant corrosion damage was observed in SEM micrographs. Both Cu2O and Cu2S were detected by Raman spectroscopy. The detection of oxidized sulfur species (SO3 2 - and SO4 2 -) on the corroded surface by XPS/Auger confirmed that even trace amounts of dissolved O2 led to sulfide oxidation and the possible formation of potentially more corrosive species such as thiosulfate (S2O3 2 -). Under aerated conditions, extensive corrosion occurred leading to the formation of green CuII products (atacamite (Cu2(OH)3Cl)) with no detectable Cu2S formation.Within the DGR, corrosion of Cu under anoxic conditions will be limited by the available supply of sulfide, which may be produced remotely at the host rock/clay interface and/or in the porewater within the rock fractures. In the presence of even trace of dissolved O2, the corrosion process is significantly accelerated with the formation of potentially aggressive oxidized sulfur species. Under aerated conditions, extensive corrosion due to reaction with O2 leads to the deposition of CuII deposits. On the time scale of these experiments with only trace of sulfide present, no detectable conversion of copper oxide to Cu2S was observed. Keywords: Copper; Sulfide; Corrosion; Nuclear waste disposal

Controlled Delivery of 2-Mercapto 1-Methyl Imidazole by Metal-Organic Framework for Efficient Inhibition of Copper Corrosion in NaCl Solution.

In this paper, zeolitic imidazolate framework-8 was modified by N-(3-aminopropyl)-imidazole to obtain a novel MOF called AMOF. Subsequently, AMOF served as a carrier for the delivery of 2-mercapto-1-methyl imidazole (MMI) to inhibit the corrosion of Cu. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were applied to characterize the morphologies and structures of AMOF and AMOF@MMI. Ultraviolet-visible spectroscopy and thermogravimetric analysis were adopted to value the capacity of the load and release of the AMOF, respectively. The mass ratio of loaded MMI molecules was 18.15%. In addition, the inhibition behavior of AMOF@MMI for Cu was evaluated by polarization curves and electrochemical impedance spectroscopy. The results indicated that the AMOF loaded MMI successfully, and the released MMI could adsorb on the Cu surface and inhibit the Cu corrosion. The inhibition efficiency could reach 88.2%. The binding and interaction energies between the AMOF surface and the MMI were -16.41 kJ/mol and -20.27 kJ/mol.

The effective and sustainable application of a green amino acid-based corrosion Inhibitor for Cu metal

The human body is a remarkably aggressive medium and applied materials must be extremely resistant to corrosion and destruction, so copper, which is a biological material and is widely used in medicine, is being considered. Copper corrosion may be associated with inflammation in body because it releases ions that are toxic to humans. In aggressive solutions, biomolecules called amino acids act as corrosion inhibitors. In the present research, the purpose is to study the inhibitory action of l-alanine (L-Ala) and l-Leucine (L-Leu) amino acids on the corrosion of Cu. By density functional theory (DFT), inhibition behavior of l-Ala-and l-Leu-and their conformers against Cu corrosion have been investigated. According to values of back-donation of electrons (Eback-d), fraction of electron transferred (ΔN), electrophilicity (ω), electronegativity (χ), softness (σ), hardness (η), energy gap (Eg), ELUMO, and EHOMO computed reactivity factors between copper surface and inhibitors are studied. l-Leu's theoretical indicators confirm its tendency towards adsorption. l-Leu-activity against corrosion has been investigated and favorable results have been obtained.

Surface Interaction Effect and Mechanism of Methionine Derivatives as Novel Inhibitors for Alkaline Copper CMP: Insights from Molecular Simulation and Experimental Analysis

To prevent excessive corrosion caused by the slurry in the copper (Cu) chemical mechanical polishing (CMP) process, a corrosion inhibitor is normally required. In this study, the methionine (Met) derivative FMOC-L-Methionine (Fmoc-Met-OH) was explored as a corrosion inhibitor for Cu film CMP in weak alkaline conditions (pH = 8.5). A comprehensive evaluation was conducted to confirm the efficiency of Fmoc-Met-OH as a corrosion inhibitor, combining experiments and theoretical calculations. The results showed that Fmoc-Met-OH could effectively inhibit the corrosion of Cu, with a high inhibition efficiency (IE) of 78.26% while maintaining a high removal rate (RR) of 5703 Å min−1, a low static etch rate (SER) of 676 Å min−1, and a low surface root mean square deviation (Sq) of 1.41 nm. Simultaneously, the results of X-ray photoelectron spectroscopy (XPS) tests and electrochemical analysis confirm that Fmoc-Met-OH molecules can form a dense and ordered adsorption film on the Cu surface. According to the density functional theory (DFT) calculations and molecular dynamics (MD) simulation, it was verified that Fmoc-Met-OH exhibited strong chemical adsorption on Cu substrates, as evidenced by the high binding energy (E Binding) value, low energy gap (ΔE), and radial distribution function (RDF) analysis. The findings provided theoretical evidence of the better inhibition effectiveness of Fmoc-Met-OH at a molecular or atomic level.

Electrochemical and theoretical (DFT, MC, MD) evaluation of a new compound based on mercaptobenzimidazole against corrosion of Cu–30Ni in a 3% NaCl solution

Electrochemical and theoretical (DFT, MC, MD) evaluation of a new compound based on mercaptobenzimidazole against corrosion of Cu–30Ni in a 3% NaCl solution

Insights into the Anticorrosion Performance of Solanum lyratum Leaf Extract for Copper in Sulfuric Acid Medium.

In this paper, Solanum lyratum leaves were prepared into a corrosion inhibitor by a pure water extraction method. As a natural plant, S. lyratum leaf extract as a corrosion inhibitor has green features. S. lyratum leaf extract (SLLE) can effectively inhibit the corrosion of Cu in H2SO4 solution. The protective effect on copper in 0.5 mol/L H2SO4 solution was studied by electrochemical measurement, Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and theoretical calculation. These results showed that the maximum corrosion inhibition efficiency (η) of SLLE for copper obtained in the electrochemical measurement at different temperatures is more than 90%. The adsorption of SLLE on copper surfaces conforms to the Langmuir isotherm adsorption model. FTIR and XPS showed the bonding information. SEM and AFM proved that the SLLE can protect the copper from corrosion media. The interaction and inhibition mechanism between the SLLE and copper surface was further revealed at the molecular level by theoretical calculation.

Photoelectrochemical effect of Cu2O on the corrosion behavior of Cu in sodium sulfate solution

The electrochemical associated with photoelectrochemical behaviors of Cu electrodeposited with Cu2O layer were investigated in this work. The corrosion of Cu was promoted due to the enhanced anodic and cathodic processes under AM 1.5illumination compared with that in the darkness, especially for the anodic process. The photoinduced corrosion of Cu by Cu2O was detected by Scanning Vibrating Electro Technique (SVET). The effect of Cu2O on the promotion of Cu corrosion under illumination can be ascribed to the narrowed depletion layer in Cu2O under illumination, which facilitates the separation of hole-electron pairs. The resultant holes give rise to the oxidation of the Cu matrix and lead to a promoted corrosion consequently. Besides, a method for in-situ determining the photoinduced current of a semiconductor material is proposed.

Surface Corrosion Inhibition Effect and Action Mechanism Analysis of 5-Methyl-Benzotriazole on Cobalt-Based Copper Film Chemical Mechanical Polishing for GLSI

With integrated circuit (IC) technology nodes below 20 nm, the chemical mechanical polishing (CMP) of cobalt (Co)-based copper (Cu) interconnection has been gradually changed to one-step polishing, which requires rapid removal rate (RR) of Cu while controlling the height differences of concave and convex areas on the Cu surface, and finally achieving global planarization. Co as the barrier material is also required a lower RR to ensure a high Cu/Co removal rate selection ratio. Therefore, choosing the appropriate inhibitor in the slurry is extremely important. The corrosion inhibitor 5-methyl-benzotriazole (TTA) was thoroughly examined in this study for its ability to prevent corrosion on Cu film as well as its mode of action. The experimental results showed that TTA can effectively inhibit the removal of Cu under both dynamic and static conditions, which was also confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) tests. The corrosion inhibition effect and mechanism of TTA was further revealed by open circuit potential (OCP), polarization curve, adsorption isotherm, quantum chemical calculation, UV–Visible and X-ray photoelectron spectroscopy (XPS) tests. It was found that TTA can inhibit the corrosion of Cu by physical and chemical adsorption on the Cu surface, which is conductive to obtain excellent planarization properties. At the same time, it was also found TTA can also inhibit the corrosion of Co by forming Co-TTA and promoting the conversion of Co(OH)2 to Co3O4, and a Cu/Co removal rate selection ratio of 104 was obtained, which provides a suitable corrosion inhibitor for the polishing of Co-based Cu interconnection CMP and has a broad application prospect.

Applying state‐of‐the‐art microscopy techniques to understand the degradation of copper for nuclear waste canisters

AbstractThe metallurgy, mechanical properties, and corrosion of Cu, proposed as the corrosion barrier for Canadian used fuel containers (UFCs) for use in a deep geological repository (DGR), have been studied for decades. Bulk properties have been reported, and the knowledge applied to strengthen the performance of Cu produced by electrodeposition and cold spray. Despite this success, many degradation mechanisms are unclear from bulk testing, which cannot capture nanoscale phenomena driving degradation. This study provides examples using state‐of‐the‐art microscopy to understand mechanisms of Cu degradation, specifically for UFCs. Subtle changes in the electrodeposited Cu microstructure due to oxygen segregation are observed using atom probe tomography (APT). In aggressive sulfide‐containing environments, corrosion of the cold‐sprayed Cu occurs along particle–particle interfaces, likely inherent to the manufacturing process. Microscale tensile testing at particle–particle interfaces confirms brittle cracking in the cold‐sprayed Cu. Although experiments are not consistent with DGR conditions, results do warrant further study on the performance of the cold‐sprayed Cu in particular.

Effect of Amino Acids on the Corrosion and Metal Release from Copper and Stainless Steel

Copper (Cu) and stainless steel 316 L are widely used for biomedical applications, such as intrauterine devices and orthopedic/dental implants. Amino acids are abundantly present in biological environments. We investigated the influence of select amino acids on the corrosion of Cu under naturally aerated and deaerated conditions using a phosphate-free buffer. Amino acids increased the corrosion of Cu under both aeration conditions at pH 7.4. Cu release was also significantly (up to 18-fold) increased in the presence of amino acids, investigated at pH 7.4 and 37 °C for 24 h under naturally aerated conditions. Speciation modelling predicted a generally increased solubility of Cu in the presence of amino acids at pH 7.4. 316 L, investigated for metal release under similar conditions for comparison, released about 1,000-fold lower amounts of metals than did Cu and remained passive with no change in surface oxide composition or thickness. However, amino acids also increased the chromium release (up to 52-fold), significantly for lysine, and the iron release for cysteine, while nickel and molybdenum release remained unaffected. This was not predicted by solution speciation modelling. The surface analysis confirmed the adsorption of amino acids on 316 L and, to a lower extent, Cu coupons.

Electrochemical Performance of Galvanic Cell with Silver Coated Cathode in One Compartment System Using Seawater as Electrolyte

This research was carried out to evaluate the electrochemical performance of a galvanic cell using seawater as an electrolyte. The cell was designed to have a volume of 200 mL and equipped with Zn as an anode and Ag-coated Cu as a cathode (Cu(Ag)-Zn system) in order to suppress the corrosion of Cu. As a comparison, the same experiment with the use of uncoated Cu as a cathode (Cu-Zn system) was also conducted. To conduct the experiment, a system was assembled by connecting 20 cells in series and placed in a closed container filled with seawater. The experiment was run for 72 hours, divided into three 24-hour cycles, by replacing the seawater every 24 hours. The performance of the system was evaluated in terms of open circuit voltage, close circuit voltage, current, light intensity, internal resistance, and power. The experimental results show that the corrosion rate of Cu coated with silver was smaller than that of uncoated Cu. Compared to the performance of the Cu-Zn system, it was also found that the Cu(Ag)-Zn system produced higher power and light intensity, which is in accordance with its smaller internal resistance. The overall experimental results indicate better performance of Cu(Ag)-Zn system and this better performance is attributed to the significantly lower corrosion rate of Cu(Ag) cathode which signifies the role of Ag layer to protect the Cu from attack by seawater. As a result, the Cu(Ag)-Zn system maintained the cathode corrosion rate with a ratio of 0.19. The percentage decrease of the OCV of the Cu(Ag)-Zn system was 6.14%, the CCV on the third day was 0.99%, the current was 36.68%, and the power was 37.83%.

Thin-Film Coating of the Hydrophobic Lotus Leaf on Copper by the Floating Film Transfer Method and Investigation on the Corrosion Behavior of Coated Copper in Saline Water

Copper (Cu) is an important base material for many electrical, thermal, and home applications. However, corrosion of Cu is a serious concern in chloride-containing solutions. The present work reports lotus leaf coating on Cu as a successful preventive solution. After preparation of a lotus leaf chloroform extract (LLCE), an ultrathin (15 ± 5 nm) film of LLCE is created by the floating film transfer method (FFTM) and transported on Cu through stamping. LLCE has been characterized by UV–visible spectroscopy (UVS), nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy (FTIRS) techniques, which disclose that LLCE meets the expectations of being rich in biomolecules. The LLCE coating on Cu was done in a layerwise manner (1–3) and analyzed with scanning electron microscopy (SEM) and a drop shape analyzer (DSA). The SEM images show that there are films on Cu, and DSA suggests that LLCE coatings have increased the hydrophobicity of Cu (contact angle 96) to greater than 100. Open-circuit potential (OCP) curves, Tafel polarization (TP) curves, electrochemical impedance spectroscopy (EIS), SEM, energy-dispersive X-ray (EDX) spectroscopy, and atomic force microscopy (AFM) have been deployed to investigate the LLCE-coated Cu corrosion in 0.5 M sodium chloride. The LLCE film of three layers (3L) on Cu is found to be the most efficient (97%, TP) against corrosion among the tested ones. SEM and AFM images evidently show that the 3L-coated Cu was the least damaged through corrosion. The reason for prevention can be recommended as blockage of the openings on the bare Cu surface by LLCE films.

3D imaging of micro-segregation and corrosion behavior of alloying elements in archaeological artefacts from Motya (Sicily, Italy)

Multiscale X-ray Microscopy, SEM, HR-FESEM- EDS and EMPA techniques have been used to explore the corrosion behavior of copper-based artefacts from the Phoenician-Punic site of Motya (Sicily, Italy). The stress corrosion, due to forging conditions, and dealloying have been investigated using 3D-imaging. At sub-micro-scale the results highlighted grain boundaries micro-segregations induced by As and the occurrence of copper-iron arsenate layers in a Cu-nail. Binary and ternary alloys revealed a marked enrichment of Sn content and a selective corrosion of Cu as determined by the calculation of dissolution factors.

Construction of Co(CO3)0.5OH/Cu Mott-Schottky heterojunctions on Ni foams as an efficient electrocatalyst for oxygen evolution reaction

Oxygen evolution reaction (OER) is an important semi-reaction in the electrolysis of water, but it requires a cheap and efficient catalyst to solve the inherent problem of slow kinetics. In this work, we present an efficient strategy to improve electrocatalytic performance by constructing a Mott-Schottky heterojunction via the Cu layer. The Co(CO3)0.5OH/Cu/NFs sample with a Mott-Schottky structure was prepared by depositing Co(CO3)0.5OH nanowire arrays on the surface of NFs plated with a Cu layer. The sample can deliver much better OER performance given the low overpotential of 253 mV at 10 mA cm−2, and extremely low Tafel slope of 48 mV dec−1, even lower than that of commercial OER catalyst RuO2. The significant performance enhancement can be attributed to the Mott-Schottky structure of Co(CO3)0.5OH/Cu. In particular, the intrinsic activity of the sample is improved by the Mott-Schottky structure of Co(CO3)0.5OH/Cu, in which the spontaneous electron will transfer from Cu to Co(CO3)0.5OH, hence reducing the OER overpotential. Then, the conductivity of the sample is initially enhanced by the Cu layer, thus improving the charge transport speed in the process of OER. Furthermore, in the constructed sandwich structure, the dense Co(CO3)0.5OH and NF substrates can avoid the corrosion of Cu by the electrolyte, maintaining good stability beyond 50 h. This strategy is also applicable to other OER materials, such as NiFe LDH, CuNi LDH, and CoP, and their performances can be significantly improved. This work provides a universal method of constructing efficient Mott-Schottky electrocatalysts for OER, consequently providing a wide range of application prospects.

Biomimetic slippery liquid-infused porous surface on the basis of hierarchical ZIF-67@Cu dendrite: Preparation and corrosion inhibition

In the harsh environment, the corrosion of Cu leads to the failure of pipelines, condenser, printed circuit board and so forth. Thus, protecting Cu from corrosion is critically important from both science and engineering backgrounds. In this report, the hierarchical structure compositing dendritic Cu and ZIF-67 is prepared onto Cu by a two-step electrodeposition protocol. After thiol modification and oil infusion, bio-inspired superhydrophobic surface (SHS) and slippery liquid-infused porous surface (SLIPS) is respectively achieved, and sophisticated techniques are used for characterizing chemical composition, morphology, topology and wettability. Scanning Kelvin probe is employed to know the surface potential distribution before and after the biomimetic transformation. Using different electrochemical approaches, the corrosion inhibition effect is elucidated. In 3.5 wt% NaCl corrosive medium, |Z|0.01Hz of SLIPS is as high as 1.35 × 108 Ω·cm2 at the initial immersion stage. The value is remarkably enhanced compared with SHS (6.76 × 104 Ω·cm2) and bare Cu (8.74 × 103 Ω·cm2). After soaking for 168 h, |Z|0.01Hz value of SHS and SLIPS is 3.84 × 104 Ω·cm2 and 4.93 × 106 Ω·cm2, illustrating that SLIPS has high resistance to protect Cu from corrosion.