Showing papers on "Electroplating published in 2018"

A capacity recoverable zinc-ion micro-supercapacitor

Abstract: To achieve high energy and power density simultaneously in miniaturized electronic devices, a zinc-ion micro-supercapacitor (ZmSC) is constructed for the first time by integrating a battery-type zinc micro-anode and a capacitor-type carbon nanotube micro-cathode. In the meantime, an electroplating method is developed to in situ replenish the zinc anode when needed without destroying the configuration of the ZmSC, in which the micro-cathode, micro-anode and electrolyte of the ZmSC function as the working electrode, counter electrode and plating solution in the plating process, respectively. This strategy effectively avoids the irreversible consumption of the zinc anode and the fading of the capacitance and cycle life. As a result, the prepared ZmSC exhibits an excellent electrochemical performance, including a high area capacitance of 83.2 mF cm−2 at 1 mA cm−2, a high energy density of 29.6 μW h cm−2 and a high power density of 8 mW cm−2. After 6000 cycles, the ZmSC shows about 87.4% retention (60.9 mF cm−2) of its initial area capacitance at 5 mA cm−2. Furthermore, a higher capacitance (76 mF cm−2) and a longer cycling life are obtained after re-plating the zinc anode. This method features a simple configuration and easy operation, and holds great promise for use in other long cycle life zinc-based microdevices.

Highly Sustainable Zinc Anodes for a Rechargeable Hybrid Aqueous Battery.

Abstract: The synthesis of novel zinc electrodes has been successfully implemented by the electroplating method with the aid of inorganic additives in the electroplating solution. The selected inorganic additives are indium sulfate, tin oxide, and boric acid. From X-ray diffraction results, the synthesized zinc electrodes prefer (002) and/or (103) crystallographic orientations, representing basal morphology and high resistance to dendrite growth. The corrosion rates of these electroplated zinc samples decrease as much as 11 times smaller than the rate of a zinc foil when the zinc materials are in contact with the aqueous electrolyte of a rechargeable hybrid aqueous battery (ReHAB). The ReHAB employing these anodes exhibits up to threefold decrease in float charge current density after a seven-day constant-voltage charging at 2.1 V vs. Zn2+/Zn. Furthermore, the capacity retentions are up to 15% higher than the performance of battery containing commercial Zn after 1000 cycles of charge-discharge. The significant advancements are attributed to the careful preparation of the anode, which contains appropriate crystallographic orientation and morphology.

Selective Electrochemical Reduction of CO2 to CO on Zn-Based Foams Produced by Cu2+ and Template-Assisted Electrodeposition.

Abstract: In this work, we aim to develop a Zn-based metal foam catalyst with very large specific area suitable for efficient CO production. Its manufacture is based on the dynamic hydrogen bubble template method that consists of the superposition of metal deposition and hydrogen evolution at the solid-liquid interface. We employed Cu ions in the Zn2+-rich electroplating bath as foaming agent. The concentration of Cu as foaming agent was systematically studied and an optimized Zn94Cu6 foam alloy was developed, which, to the best of our knowledge, is the most selective Zn-based CO2 electrocatalyst toward CO in aqueous bicarbonate solution (FECO = 90% at -0.95 V vs reversible hydrogen electrode). This high efficiency is ascribed to the combination of high density of low-coordinated active sites and preferential Zn(101) over Zn(002) texturing. X-ray photoelectron spectroscopy investigations demonstrate that the actual catalyst material is shaped upon reduction of an oxide/hydroxide-terminating surface under CO2 electrolysis conditions. Moreover, intentional stressing by oxidation at room conditions proved to be beneficial for further activation of the catalyst. Identical location scanning electron microscopy imaging before and after CO2 electrolysis and long-term electrolysis experiments also showed that the developed Zn94Cu6 foam catalyst is both structurally and chemically stable at reductive conditions.

Dendrite‑Free Epitaxial Growth of Lithium Metal during Charging in Li–O 2 Batteries

Abstract: Lithium (Li) dendrite formation is one of the major hurdles limiting the development of Li-metal batteries, including Li-O2 batteries. Herein, we report the first observation of the dendrite-free epitaxial growth of a Li metal up to 10-μm thick during charging (plating) in the LiBr-LiNO3 dual anion electrolyte under O2 atmosphere. This phenomenon is due to the formation of an ultrathin and homogeneous Li2 O-rich solid-electrolyte interphase (SEI) layer in the preceding discharge (stripping) process, where the corrosive nature of Br- seems to give rise to remove the original incompact passivation layer and NO3- oxidizes (passivates) the freshly formed Li surface to prevent further reactions with the electrolyte. Such reactions keep the SEI thin (<100 nm) and facilitates the electropolishing effect and gets ready for the epitaxial electroplating of Li in the following charge process.

Epitaxial-Growth-Induced Junction Welding of Silver Nanowire Network Electrodes

Abstract: In this study, we developed a roll-to-roll Ag electroplating process for metallic nanowire electrodes using a galvanostatic mode. Electroplating is a low-cost and facile method for deposition of metal onto a target surface with precise control of both the composition and the thickness. Metallic nanowire networks [silver nanowires (AgNWs) and copper nanowires (CuNWs)] coated onto a polyethylene terephthalate (PET) film were immersed directly in an electroplating bath containing AgNO3. Solvated silver ions (Ag+ ions) were deposited onto the nanowire surface through application of a constant current via an external circuit between the nanowire networks (cathode) and a Ag plate (anode). The amount of electroplated Ag was systematically controlled by changing both the applied current density and the electroplating time, which enabled precise control of the sheet resistance and optical transmittance of the metallic nanowire networks. The optimized Ag-electroplated AgNW (Ag-AgNW) films exhibited a sheet resistan...

Selective electroplating of 3D printed parts

Abstract: Fused filament fabrication (FFF) 3D printers have been largely limited to thermoplastics in the past but with new composite materials available on the market there are new possibilities for what these machines can produce. Using a conductive composite filament, electronic components can be manufactured but due to the filament’s relatively poor electrical properties, the resulting traces are typically highly resistive. Selective electroplating on these parts is one approach to incorporate materials with high conductivity onto 3D-printed structures. In this paper, non-conductive and conductive filaments printed in the same part are used to enable selective electroplating directly on regions defined by the conductive filament to create metallic parts through 3D printing. This technique is demonstrated for the creation of multiple distinct conductive segments and to electroplate the same part with multiple metals to, for instance, allow a magnetic metal such as nickel and a highly conductive one such as copper to be incorporated in the same part. Following the characterization of the process, a representative 3D printed electrical device, a selectively electroplated solenoid inductor with low frequency inductance and resistance of 191 nH and 18.7 mΩ respectively was manufactured using this technique. This is a five order of magnitude reduction in resistance over the original value of 3 kΩ for the inductor before electroplating.

Electroplating of Semiconductor Materials for Applications in Large Area Electronics: A Review

Abstract: The attributes of electroplating as a low-cost, simple, scalable, and manufacturable semiconductor deposition technique for the fabrication of large-area and nanotechnology-based device applications are discussed. These strengths of electrodeposition are buttressed experimentally using techniques such as X-ray diffraction, ultraviolet-visible spectroscopy, scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, and photoelectrochemical cell studies. Based on the results of structural, morphological, compositional, optical, and electronic properties evaluated, it is evident that electroplating possesses the capabilities of producing high-quality semiconductors usable for producing excellent devices. In this paper we will describe the progress of electroplating techniques mainly for the deposition of semiconductor thin film materials and their treatment processes, and fabrication of solar cells.

An electroplated copper–silver alloy as antibacterial coating on stainless steel

Abstract: Transfer and growth of pathogenic microorganisms must be prevented in many areas such as the clinical sector. One element of transfer is the adhesion of pathogens to different surfaces and the purpose of the present study was to develop and investigate the antibacterial efficacy of stainless steel electroplated with a copper-silver alloy with the aim of developing antibacterial surfaces for the medical and health care sector. The microstructural characterization showed a porous microstructure of electroplated copper-silver coating and a homogeneous alloy with presence of interstitial silver. The copper-silver alloy coating showed active corrosion behavior in chloride-containing environments. ICP-MS measurements revealed a selective and localized dissolution of copper ions in wet conditions due to its galvanic coupling with silver. No live bacteria adhered to the copper-silver surfaces when exposed to suspensions of S. aureus and E. coli at a level of 108 CFU/ml whereas 104 CFU/cm2 adhered after 24 h on the stainless steel controls. In addition, the Cu-Ag alloy caused a significant reduction of bacteria in the suspensions. The coating was superior in its antibacterial activity as compared to pure copper and silver electroplated surfaces. Therefore, the results showed that the electroplated copper-silver coating represents an effective and potentially economically feasible way of limiting surface spreading of pathogens.

Surface metallization of ABS plastics for nickel plating by molecules grafted method

Abstract: The surface activation of ABS plastics was achieved by novel palladium-free pretreatments that consisted of molecular grafting and self-assembling. Silver mirror reaction has been developed to prepare silver films on ABS plastics by solution spray. There is an excellent adhesion between the substrate and Ag films as the molecular bonding force is larger than the mechanical anchoring force by conventional sensitizing-activation method. A compact copper coating was prepared on the Ag films to make the products to adapt to a variety of environments, and double‑nickel electroplated coats were achieved to enhance corrosion resistance. X-ray photoelectron spectroscopy (XPS) analysis provided useful data on surface functionality. X-ray diffraction (XRD) result revealed pure silver films on ABS. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to characterize the coatings morphologies.

Solvent extraction of nickel ions from electroless nickel plating wastewater using synergistic green binary mixture of D2EHPA-octanol system

Abstract: A study on the synergistic green solvent extraction of nickel ions from real electroless nickel plating wastewater using an organic phase containing a binary mixtures of Di (2-ethylhexyl) phosphoric acid (D2EHPA) and octanol in palm oil was conducted. The effects of diluent composition, synergist, carrier and stripping agent types and its concentrations were experimentally investigated and the optimum conditions were determined. Results revealed that both D2EHPA and octanol acted as a carrier and synergist, respectively. A significant synergistic effect occurred when the octanol helped destroy the dimer structure of D2EHPA for cation exchange mechanism with nickel ions, hence improving the nickel ions extraction up to 90% with the maximum distribution ratio of 8.8 under optimum condition of 0.7M D2EHPA and 15% (v/v) octanol in palm oil. Afterwards, the stripping experiment showed that nickel ions could be recovered from the loaded mixture of carrier using 1.0M nitric acid solutions. Besides, the slope analysis method showed that the nickel ions were extracted from weak acidic electroplating feed solution as nickel-D2EHPA-octanol complex and recovered as nickel nitrate complex in the stripping phase. Thus, it can be concluded that the green synergistic formulation containing binary mixtures of D2EHPA-octanol system is one of the promising approaches as well as a green and efficient separation method for nickel ions extraction from the real electroless nickel plating wastewater.

Study on hydrophobicity and wettability transition of Ni-Cu-SiC coating on Mg-Li alloy

Abstract: A high hydrophobic Ni-Cu-SiC coating with a graded nanostructure was successfully deposited on the Mg-Li alloy via electroplating and stearic acid modification. After stearic acid modification, the as-prepared Ni-Cu-SiC coating displays high hydrophobicity with contact angle of 156.0°. Furthermore, surface wettability transition from high hydrophobicity to superhydrophilicity can be achieved via UV–vis irradiation, and subsequently, the high hydrophobicity can recover to hydrophobicity via stearic acid re-modification. This work could provide a novel way to fabricate functional surface on Mg-Li alloy and wider industrial application for Mg-Li alloy.

Diode Laser Welding/Brazing of Aluminum Alloy to Steel Using a Nickel Coating

Abstract: Joining Al alloy to steel is of great interest for application in the automotive industry. Although a vast number of studies have been conducted to join Al to steel, the joining of Al to steel is still challenging due to the formation of brittle Fe–Al intermetallic compounds. In this work, the microstructure and mechanical properties of the dissimilar Al/steel joints with and without a nickel coating are comparatively investigated. A homogenous reaction layer composed of FeZn10 and Fe2Al5 is formed at the interface in the joints without Ni coating, and the joint facture load is only 743 N. To prevent the formation of brittle Fe2Al5, Ni electroplated coating is applied onto a steel surface. It has been shown that a nonhomogeneous reaction layer is observed at the interfacial region: Ni5Zn21 is formed at the direct irradiation zone, while Al3Ni is formed at the fusion zone root. The microhardness of the interfacial layer is reduced, which leads to the improvement of the joint mechanical properties. The average fracture load of the Al/Ni-coated steel joints reaches 930 N. In all of the cases, failure occurs at the Ni coating/fusion zone interface.