Electroless Deposition Of Silver Research Articles

Bioinspired interlaced wetting surfaces for continuous on-demand emulsion separation

Maintaining high separation performance during continuous emulsion separation remains a challenge. Herein, based on biomimetic coupling ideas, hole array interlaced wetting surfaces (HAIWSs) and mastoid array interlaced wetting surfaces (MAIWSs) were prepared by laser processing, electroless silver deposition, thiol modification, and spraying for on-demand emulsion separation. When the separation is going on, randomly moving emulsion droplets are prone to being captured by holes or mastoids due to interlaced wettability. Under this unique interface behavior, the occurrence of filter cake and pore clogging is reduced, thus achieving both high efficiency (~99.5 and ~99.3%). Meanwhile, the high flux can also be maintained (~3212 and ~3458Lm-2 h-1). Significantly better than surfaces without pores or mastoid structures. Further, the as-prepared surfaces also exhibit excellent recyclability. After 50 separation cycles, optimized HAIWS and MAIWS still maintained high efficiency (~96.2 and ~95.8%) and high flux (~3042 and ~3164Lm-2 h-1), exceeding other surfaces without hole or mastoid structure. Notably, complex physical/chemical cleaning processes are avoided. Besides, even in harsh conditions, HAIWS and MAIWS still maintain excellent stability. The above strategy provides a novel mechanism for effective on-demand emulsion separation and is expected to encourage the creation of new-class separation devices for oily wastewater treatment in industry.

Preparation and optimization of conductive PDMS composite foams with absorption-dominated electromagnetic interference shielding performance via silvered aramid microfibers

Electromagnetic interference (EMI) shielding materials with absorption-dominated EMI shielding mechanism can effectively annihilate electromagnetic waves (EMW) and avoid their repeated EMW pollution. However, it is difficult to achieve this goal for conductive polymer-based composites (CPC), because the interface impedance mismatch between air and CPC leads to massive reflection of EMW at the interface. Pores are beneficial to EMW penetrating into the interior of CPC and causing their multiple reflection, scattering and absorption in pores, thus endowing CPC with absorption-dominated EMI shielding characteristic. Herein, highly conductive silvered aramid microfibers (CAMF) were first synthesized via dopamine-assisted electroless deposition of silver coating on aramid microfibers (AMF), and then the conductive porous PDMS composite foams (PDMSF) with absorption-dominated EMI shielding characteristic were prepared and optimized via salt template method. As a result, PDMSF with 1.7 vol% silver content, the conductivity of PDMSF can reach 10-1 S/m, the EMI shielding efficiency (EMI SE) can reach 36.7 dB in X-band, and the average absorption ratio in EMI SE is 87%, while the density of PDMSF is only 0.28 g/cm3. The combination of lightweight, high EMI SE and absorption-dominated EMI shielding characteristic makes the porous PDMSF the latent EMI shielding materials in special constructions (e.g. military, confidential and nuclear facilities, etc.), aerospace, military equipments and transportation, etc.

Kinetics and Mechanism of Electroless Silver Deposition on a Polyurethane Substrate at Moderate to High Concentration of Metal Precursor and Reductant

Kinetics and Mechanism of Electroless Silver Deposition on a Polyurethane Substrate at Moderate to High Concentration of Metal Precursor and Reductant

Design and Achievement of Superfilling Electroless Silver Deposition for Micrometer Trenches

Design and Achievement of Superfilling Electroless Silver Deposition for Micrometer Trenches

Janus metallic film with gold and silver luster by electroless deposition of silver using poly(dopamine acrylamide) thin film.

Films that exhibit different metallic luster on the front and back, called Janus metallic films, have broad applications ranging from design materials to optical devices. However, the fabrication of these films is often a complicated process involving multiple metal deposition steps, thermal annealing, and calcination. Herein, we report the simple preparation of a Janus metallic film by electroless deposition of silver on a poly(dopamine acrylamide) (pDOPAm) thin film. pDOPAm was successfully synthesized via the controlled reversible addition-fragmentation chain transfer polymerization of dopamine acrylamide without a protective group using dimethylformamide as the solvent. The synthesized pDOPAm was spin-coated onto a solid substrate, which was then immersed in an aqueous AgNO3 solution to achieve the electroless deposition of silver. Our preparation method will considerably simplify the fabrication of Janus metallic films, enabling their widespread application as decorative or authentication materials.

Silicon Nanowires Decorated with Silver Nanoparticles for Photoassisted Hydrogen Generation

Highly n-doped silicon nanowires (SiNWs) decorated with silver nanoparticles (AgNPs) at the top, middle, and bottom were produced using electroless silver deposition (ELD), silver mirror reaction (MR), and native AgNPs as a reference, respectively. Subsequently, hydrogen generation on SiNWs decorated with and without AgNPs was evaluated. Our results show that SiNWs decorated with native and MR AgNPs produce the highest and the lowest hydrogen amount under white light irradiation in 3 h, respectively. Moreover, for SiNWs with native AgNPs, the morphology of SiNWs after hydrogen generation was almost the same as the original array of SiNWs before hydrogen release, even after 24 h in water/ethanol (4:1; v/v) solution. However, the geometry of SiNWs decorated without and with AgNPs by ELD and MR was collapsed after hydrogen evolution. The detailed surface studies show that the sidewall surface of SiNWs with native AgNPs has a rougher topology and formed a stable layer of SiOx in water. Our observations strongly suggest that two hydrogen generation possibilities, i.e., SiNW oxidation and photostimulation, are jointly responsible for the efficient hydrogen generation. Additionally, the presence of AgNPs on the sidewall of the SiNW matrix can enhance the hydrogen generation rate. Our results open novel perspectives for the effective hydrogen generation based on nanostructured silicon.

Enhanced Conductivity and Antibacterial Behavior of Cotton via the Electroless Deposition of Silver.

In this study, the surface-initiated atom transfer radical polymerization (SI-ATRP) technique and electroless deposition of silver (Ag) were used to prepare a novel multi-functional cotton (Cotton-Ag), possessing both conductive and antibacterial behaviors. It was found that the optimal electroless deposition time was 20 min for a weight gain of 40.4%. The physical and chemical properties of Cotton-Ag were investigated. It was found that Cotton-Ag was conductive and showed much lower electrical resistance, compared to the pristine cotton. The antibacterial properties of Cotton-Ag were also explored, and high antibacterial activity against both Escherichia coli and Staphylococcus aureus was observed.

Syntheses and Step-by-Step Morphological Analysis of Nano-Copper-Decorated Carbon Long Fibers for Aerospace Structural Applications

Carbon long fiber/copper composites were prepared using electroless and electroplating methods with copper metal for potential aerospace applications. Carbon fibers were heat-treated at 450 °C followed by acid treatment before the metallization processes. Three different methods of metallization processes were applied: electroless silver deposition, electroless copper deposition and electroplating copper deposition. The metallized carbon fibers were subjected to copper deposition via two different routes. The first method was the electroless deposition technique in an alkaline tartrate bath using formaldehyde as a reducing agent of the copper ions from the copper sulphate solution. The second method was conducted by copper electroplating on the chemically treated carbon fibers. The produced carbon fiber/copper composites were extensively investigated by Field-Emission Scanning Electron Microscopy (FE-SEM) supported with an Energy Dispersive X-Ray Analysis (EDAX) unit to analyze the size, surface morphology, and chemical composition of the produced carbon long fiber/copper composites. The results show that the carbon fiber/copper composites prepared using the electroplating method had a coated type surface morphology with good adhesion between the copper coated layer and the surface of the carbon fibers. However, the carbon fiber/copper composites prepared using the electroless deposition had a decorated type morphology. Moreover, it was observed that the metallized carbon fibers using the silver method enhanced the electroless copper coating process with respect to the electroless copper coating process without silver metallization. The electrical conductivity of the carbon fiber/copper composites was improved by metallization of the carbon fibers using silver, as well as by the electrodeposition method.

Enhancing Effect of Chloride Ions on the Autocatalytic Process of Ag(I) Reduction by Co(II) Complexes.

In this work, the possibilities of increasing the rate of electroless silver plating without a rise in the concentration of reactants or elevation of temperature were studied. The effect of halide additive, namely chloride ions, on the rate of electroless silver deposition was investigated, using conventional chemical kinetics and electrochemical techniques. It was found that the deposition rate of electroless silver increased 2–3 times in the presence of 10–20 mM of chlorides, preserving sufficient stability of the solution.

Corrosion Protection of Nano-biphasic Calcium Phosphate Coating on Titanium Substrate

Background: Increasing the bioactivity of metallic implants is necessary for biomaterial applications where hydroxyapatite (HA) is used as a surface coating. In industry, HA is currently coated by plasma spraying, but this technique has a high cost and produces coating with short-term stability. Objectives: In the present study, electrophoretic deposition (EPD) was used to deposit nano-biphasic calcium phosphate compound (β-tri-calcium phosphate (β-TCP) /hydroxyapatite (HA)) bio-ceramics on the titanium surface. The microstructural, chemical compositions and bioactivity of the β- TCP/HA coatings were studied in a simulated body fluid solution (SBF). Methods: Scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) were used. Additionally, the antibacterial effect was studied by the agar diffusion method. The corrosion behavior of the β-TCP/HA coating on titanium surface (Ti) in the SBF solution at 37oC was investigated by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests. Results: The Ti surface modification increased its biocompatibility and corrosion resistance in the simulated body fluid. The antibacterial inhibition activity of the β-TCP/HA bio-ceramic was enhanced by electroless silver deposition. The enhanced properties could be attributed to the use of nano-sized biphasic calcium phosphates in a low-temperature EPD process. Conclusions: The β-TCP/HA and β-TCP/HA/Ag coatings well protect Ti from the corrosion in SBF and endow Ti with biocompatibility. The β-4-TCP/HA/Ag/Ti substrate shows good antibacterial activity.

Capacitive Humidity Sensing Characeristics of Porous Silicon Oxide Via Electrodeposition Assisted Stripping and Metal Assisted Chemical Etching Process

Sensor devices are widely used for increasing human convenience to detect various environmental parameters such as humidity, temperature, pressure and lots of hazardous chemicals. Also, specific sensor devices are utilized for private security using iris or finger print. Among them, humidity sensors are widely utilized in the fields of food science, meteorology, preservation of relics, so on [1-2]. Therefore, measuring the humidity is substantial interest in research fields. For detecting the humidity, many materials including silicon, silicon oxide, metal oxide, conducting polymers, and carbon group materials have been used. Among them, silicon oxide is considered because of its low process cost and simple fabrication process. Moreover, silicon oxide is hydrophilic materials that water molecules were easily adsorbed on its surface. In order to increasing sensing characteristics, lots of researchers put an enormous efforts such as increasing surface to volume ratio, improving the structure of sensor device, and doping the impurities to electrode materials and so on. Among them, increasing the effective surface area is the most common and simple way to enhancing the sensing characteristics. Electrodeposition assisted stripping (EAS) process is the one of the most effective kerf-free method for obtaining the thin silicon film [3]. The EAS process is using a spalling which is the unique mode of brittle fracture, caused by high tensile stress. High tensile stressed layer can induce fracture at a certain depth, parallel to substrate interface, which was deposited by electrochemical deposition of nickel layer on the silicon surface. In order to control the thickness of spalled silicon layer, current density is the critical parameter of electrodeposition process. Metal assisted chemical etching (MACE) process is utilized to fabricate the porous structure. The MACE process is using the anisotropic etching phenomenon through metal catalysts in wet etching solution, which is consisted of hydrogen peroxide and hydrofluoric acid. Compared to dry etching process, MACE can fabricate the high aspect ratio of porous structure much easier and cheaper than vacuum based process. In this study, we fabricated the porous silicon oxide film using EAS, MACE and oxidation process and it was characterized as humidity sensor device. Before the EAS process, the thickness of 20 and 200 nm of titanium and nickel layer was deposited by E-beam evaporator. The current density of 10 mA/cm2 was conducted to deposit the high tensile stressed nickel layer in watt bath which was consisted of nickel sulfate, nickel chloride and sodium citrate. The thickness of spalled silicon layer was around 90 ~ 100 um. After the spalling the silicon, MACE and oxidation process was conducted in consecutive order. Tin and silver electro-less deposition was conducted to make the metal catalyst and hydrogen peroxide and hydrofluoric acid were used for etching electrolyte. The oxidation process was conducted in ambient air condition at 1000 ℃ in 3-zone quartz tube furnace. Surface morphology and thickness of spalled silicon were observed with field-emission scanning electron microscope (FE-SEM). Electrical characteristics of porous Si humidity sensor were characterized by 2-point probe station. The humidity was controlled by changing the ratio of dry gas to wet gas. Variation of capacitance of humidity sensor was measured and recorded using an LCR meter. The sensitivity is represented by (CDry - CRH) / CRH, where CRH is the capacitance with the varied humidity and CDry is the capacitance with the lowest humidity. Moreover, response and the recovery time are defined as the time to reach 90% of the total variation. In order to verifying the humidity sensing mechanism, electrochemical impedance spectroscopy (EIS) analysis was conducted. From the EIS results, proper equivalent circuit of humidity sensor and sensing mechanism were suggested. REFERENCES [1] P. Hurjes, A. Kovacs, Cs. Ducso, M. Adam, B. Muller, U. Mescheder, “Porous silicon-based humidity sensor with interdigital electrodes and internal heaters”, Sensors and Actuators B: Chemical 2003, 95, 140-144. [2] Z.M. Rittersma, A. Splinter, A. Bodecker, W. Benecke, “A novel surface-micromachined capacitive porous silicon humidity sensor” Sensors and Actuators B: Chemical 2000, 68, 210-217. [3] Youngim Kwon, Changyeol Yang, Sang-Hwa Yoon, Han-Don Um, Jung-Ho Lee and Bongyoung Yoo, “Spalling of a Thin Si Layer by Electrodeposit-Assisted Stripping”, Applied Physics Express, 2013, 6 (11), 116502.

Factors affecting fractal patterns obtained by electroless deposition in polymer

Electroless deposition of silver has been studied experimentally in a polymer (chitosan) with different molecular weight (∼50 000–190 000 Da and ∼600 000 Da). Transport of ions in polymers involves various dynamical processes having different time scales. The time scale of ion dynamics depends on the number of monomer chains in the polymer, i.e., the molecular weight of the polymer. Polymers of high molecular weight contain regular arrangement of long chains of monomers which generally leads to high crystallinity. Copper, zinc and aluminum wires have been used for different reaction rates in the polymer-Ag salt solution. Anisotropy of the polymer-salt solution varies due to the change in the ion dynamics in high molecular weight polymer as compared to the low molecular weight polymer. Varying anisotropy leads to different aggregation patterns around the reactive metal wires. X-ray diffraction has been performed to determine the crystallinity while the voltage-time measurement has been done to validate the aggregation process. Effect of air exposure/oxidation on the growth patterns has also been considered as the adsorption of oxygen ions changes with the change in the crystallinity of the polymer.

Formation of silver nanoparticles and their application for suppressing surface reflection of n-type silicon

In this paper silver-assisted chemical etching (SACE) was studied to increase roughness and reduce light reflection from the surface of n-type (100) mono-crystalline silicon. SACE process includes two basic steps which are silver deposition and chemical etching step. Simple electroless silver deposition step using mixture of AgNO3 and HF was utilized to form silver nanoparticles onto n-type silicon surface. Following chemical etching step was carried out by immersing samples in mixture of HF and H2O2. Concentration of AgNO3 in eletroless deposition step and concentration of HF in chemical etching step were investigated to get minimum reflectance. The surface of sample was characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM) and sample reflectance was measured at the wavelength range from 350–1100 nm. The results show that reflectance depends on AgNO3 concentration in electroless deposition step and HF concentration in etching step and the minimum solar-weighted reflectance is 1.74%. This method can be considered as simple, inexpensive method to effectively increase roughness and suppress light reflection for photovoltaic, optoelectronic, sensor, photonic applications.

Electroless Metal Deposition Using Multivalent Metal Ions As Reducing Agents

The possibility and conditions to use lower oxidation state metal ions as reducing agents for autocatalytic electroless metal deposition are discussed. The theoretical background of such kind reactions is presented in the view of thermodynamics. Kinetic data on electroless silver, copper, palladium and platinum deposition using Co(II)/Co(III) redox systems with different ligands are presented and discussed. Ti(III)/Ti(IV) redox systems with different ligands were shown also to be suitable reducing agents for reducing of Pt(IV), Pd(II), Ni(II) and Co(II) to metallic state and formation of continuous metal layer on the surface to be plated. The morphology of metal layers deposited using above-mentioned reducing agents was characterized by means of Field Emission Scanning Electron Microscopy (FESEM). Kinetics of metal deposition rate was investigated by means of the gravimetry or Electrochemical Quartz Crystal Microgravimetry (EQCM).

Bimetallic nanostructures on porous silicon with controllable surface plasmon resonance

The most intensive surface plasmon resonance (SPR) band is typical for the metallic particles of 10-150nm diameters. The SPR band of such nanoparticles is usually narrow and allows using just one laser (i.e. limited range of excitation wavelength) to achieve the maximal enhancement of electromagnetic field near metallic nanostructures caused by surface plasmon oscillations. It hinders usability of plasmonic nanostructures in some application including surface enhanced Raman scattering (SERS) spectroscopy. To overcome this hurdle enlarged metallic nanostructures are fabricated resulting in a broadening of the SPR band due to additional oscillation modes. However, the SPR bands of the enlarged particles are characterized by less intensity and weak enhancement at different wavelengths. In this paper, we proposed an alternative way for the SPR band broadening by use of bimetallic nanostructures on a sculptured template. Plasmonic substrates were fabricated by sequential copper electroplating and silver electroless deposition on porous silicon. Presented data implies that variation in morphology and ratio of the silver/copper nanostructures allow to control position of their SPR band from blue to near-infrared (IR) range. It is shown that SERS-spectroscopy with the fabricated nanostructures provide equal detection limits of rhodamine 6G under red and near-IR excitation wavelengths.

Spatially Defined, High‐Contrast, and Deformation‐Free Dopamine Subtractive Thermal Transfer Printing Using a Nonelastomeric Polymeric Mold and Its Multifunctional Applications

AbstractHere, a spatially defined high‐contrast subtractive strategy of patterning dopamine from one hard substrate onto another via thermal transfer printing is presented. Dopamine is deposited on a bare thermoplastic and then transfer‐printed onto another, on which polyethylenimine (PEI), an amine‐rich compound that acts as an adhesive, is coated. Schiff base reaction between the dopamine and amine functionalities of PEI allows for dopamine transfer from one substrate to another without pattern collapse and permits high transfer efficiency, leaving behind only the defined dopamine patterns on the bare thermoplastic substrates, where dopamine is initially coated physically. Water contact angle measurement and X‐ray photoelectron spectroscopy confirm the successful dopamine transfer. The practical applicability of this patterning method is verified by culturing human umbilical vein endothelial cells, selectively embedding micro beads into the dopamine‐coated microwell arrays formed on a hydrophobic substrate, and selective electroless deposition of silver onto the dopamine‐coated regions. This subtractive patterning method guarantees high pattern fidelity with simple operation, high homogeneity and visibility in the patterned area, and high‐contrast wettability in regard to its background, revealing its promise for future applications in biomolecule patterning and microarray chip construction.

Electroless silver plating of 3D printed waveguide components by peristaltic pump driven system

V-band waveguide components operating in 57–64 GHz ISM band is presented. Consumer-grade stereolithographic 3D printer is used to print these waveguide components with black-pigmented acrylate-based polymer. Electroless deposition of silver on these microwave components is achieved using an in-house system assembled with off-the-shelf components. This system is driven by a peristaltic pump, circling plating solution between silver bath and waveguide. Metal plated WR-15, 2-inch waveguide section offers average insertion coefficient of −0.35 dB. Trough waveguide section connected to rectangular waveguide through rectangular to trough waveguide transition is metal plated and offers average insertion coefficient of −1 dB. Silver deposited using the pump operated system offers potential of achieving comparable results as conventional dip coating technique.

On a silver platter

on a silver platter

Nanoscale morphology of electrolessly deposited silver metal

Electroless deposition of silver was studied to determine how chemical and physical parameters affect the morphology of the deposited metal. The study was conducted using variations of a silver deposition bath originally described by Danscher. The standard bath produced reflective and electrically conductive metal films comprised of agglomerates of small spheroidal nanoparticles. Removing gum arabic from the bath increased the deposition rate and changed the shape of the agglomerates but did not significantly change the size of the constituent nanoparticles. Replacing the citrate buffer with a dicarboxylate or monocarboxylate, which is less able to chelate Ag+, produced surfaces comprised of larger, more faceted metal particles. The longevity of the bath varied with the choice of carboxylate. A new formulation buffered with maleate exhibited the highest stability, depositing silver for several hours without unwanted spontaneous formation of silver metal in solution. Optical measurements of electrolessly deposited films revealed absorptions associated with silver nanoparticles. Electrical measurements showed that the as-deposited films were five orders of magnitude less conductive than bulk silver, but low-temperature annealing increased the conductivity by four orders of magnitude.

SERS based monitoring of toluene vapors at ambient and elevated temperatures by using a ruffled silver nanolayer as a substrate.

The authors describe a Surface enhanced Raman spectroscopy (SERS)-based method for the detection of gaseous toluene at different temperature regimes using 3D ruffled silver SERS substrates and a commercially available handheld Raman system equipped with a785nm laser. The 3D silver SERS substrates were synthesized via electroless deposition of silver on the ruffled sandpaper and HF-etched silicon wafers. The morphological characterization of the silver SERS substrates was carried out by atomic force microscopy and scanning electron microscopy. UV-Vis spectroscopy absorption spectra of the silver nanostructures showed plasmonicpeaks at 522nm and 731nm. Toluene vapors were collected with asyringe at ambient temperature and at 100°C, while SERS detection was always performed at room temperature. Toluene detection was based on the measurement of the Raman bands at 787cm-1 and 1003cm-1 (in thefingerprint region). The method allow gaseous toluene to be detected at its vapor concentrations of 522ppm (mg/L), 261ppm (mg/L) and 26ppm (mg/L). Graphical abstract Schematic presentation of an original method for the detection of toluene vapors by SERS technique. The collection of toluene vapors was carried out at room and at high temperatures. The vapors were transferred to methanol by bubbling. The SERS measurements were carried out at room temperature.