Electrochemical Deposition Parameters Research Articles

Fabrication of superamphiphobic micro-reentrant structures by inverted electrochemical deposition

Due to excellent oil resistance and shortened liquid-solid contact time, superamphiphobic surfaces have promising application prospects in oil transportation, and petroleum pollution control. Although superamphiphobic surfaces have been constructed on various substrates, there is still a lack of high-efficient methods for fabricating micro-reentrant structures on engineering metal substrates. This paper proposes a new method combining laser processing and inverted electrochemical deposition techniques to achieve high-efficient and large-scale fabrication of superamphiphobic surfaces on copper substrates. Firstly, micropillar array structures are constructed by laser processing, and the structures exhibit excellent superhydrophobicity after low surface energy modification. Then, inverted electrochemical deposition is performed after polishing the top of the array, and local angle of the gas/liquid interface can be controlled by adjusting the distance between the top of the micropillar and the electrolyte level, thus regulating micro-morphology of the roof structure. The influences of electrochemical deposition parameters on characteristics of the micro-reentrant structures are systematically investigated. Finally, superamphiphobic micro-reentrant structures (roof diameter > 190 μm, micropillar spacing <250 μm) with water and oil contact angles exceeding 150° are prepared after lowering the surface energy of the deposited structures. After anti-fouling, blowing, ultrasonic vibration, and tape adhesion tests, the prepared superamphiphobic micro-reentrant structures maintained good water and oil repellency, showing excellent chemical stability and durability. The research may provide a simple, efficient, and low-cost method for high-efficient constructing superamphiphobic surfaces on engineering metal substrates, enriching the fabrication techniques of micro-reentrant structures and facilitating their practical applications.

Electrodeposition of Transition Metal Dichalcogenide Thin- Films from Non-Aqueous Solvents

Transition metal dichalcogenides (TMDCs) are an interesting group of 2D materials characterised with a layered structure analogous to graphene and they possess unique electronic and optical properties, especially when in the few- and mono-layer form. Developing scalable techniques for depositing TMDCs is a major challenge which needs to be overcome to fabricate functional devices with these materials. Electrodeposition is an industrially relevant technique that has some key advantages over other conventional deposition methods. It is a low cost and easily scalable technique and could be used for obtaining complex nanoscale features and for depositing over topologically demanding surfaces. Even though the electrodeposition of MoS2 has been achieved both in aqueous and non-aqueous electrolytes, not much progress has been made in the deposition of other TMDC materials. Tungsten based TMDCs such as WS2 and WSe2 are shown to be very promising materials in different applications, however electrodepositing them remains extremely challenging. One of the major obstacles here is developing electrochemically active precursors which are compatible with the electrolyte system and able to deliver both the tungsten and chalcogens to the electrolyte. Controlling and optimizing the deposition process to obtain few- and mono-layer TMDCs is another challenge. In addition, the choice of substrates for deposition is very important, especially for direct growth of ultra-thin TMDCs. Electrodeposition, being a bottom-up deposition method, would benefit from an atomically thin and smooth substrate such as graphene for depositing few- and mono-layer TMDCs.Here we present non-aqueous electroplating as a scalable alternative technique for tungsten-based TMDC deposition, with WS2 and WSe2 as examples. Tailored single source precursors were developed to use in non-aqueous electrolytes. WS2 was electrodeposited from dichloromethane (CH2Cl2) using the [NEt4]2[WS2Cl4] precursor. WSe2 was then electrodeposited from acetonitrile (CH3CN) electrolyte using [WSeCl4] as the precursor. Electrochemical quartz crystal microbalance (EQCM) studies were performed to optimize the deposition process and to probe the mechanism of precursor electrochemistry. Electrochemical deposition parameters were then carefully adjusted to obtain few- and mono-layer TMDCs. Patterned graphene electrodes were used as an atomically thin and smooth platform for the deposition of few- and mono-layer WS2. Few-layer TMDC films obtained on graphene were found to be much smoother than films deposited on other standard substrates such as titanium nitride (TiN) or Pt. These TMDC/graphene structures gave interesting 2D heterostructures which are technologically important for different applications.This work was funded by EPSRC grant references EP/V062689/1, EP/V062387/1 and EP/P025137/1

A Review of Cobalt-Based Metal Hydroxide Electrode for Applications in Supercapacitors

Supercapacitors are the cutting-edge, high performing, and emerging energy storage devices in the future of energy storage technology. It delivers high energy and produces higher specific capacitances. This research study provides insights into supercapacitor materials and their potential applications by examining different battery technologies compared with supercapacitors’ advantages and disadvantages. Transition metal hydroxides (cobalt hydroxides) have been studied to develop electrodes for supercapacitors and their use in various fields of energy and conversion devices. Cobalt-based metal oxides and hydroxides provide high-capacitance electrodes for supercapacitors. Metal hydroxides combine high electrical conductivity and excellent stability over time. The metal oxides used to prepare the electrodes for supercapacitors are cobalt-based metal oxides and hydroxides. It is stronger than most of the other oxides and has tremendous electrical conductivity. Cobalt hydroxides are also used in supercapacitors instead of other metal hydroxides, such as aluminum hydroxide, copper hydroxide, and nickel hydroxide. This study gives a complete overview of the preparation, synthesis, analysis, and characterization of cobalt hydroxide thin film electrodes by using the electrochemical deposition technique, parameters measurements, important characteristics, material properties, various applications, and future enhancement in supercapacitors.

Electrochemical Investigation of Viral Respiratory Infection Inflammatory Biomarker Serum Amyloid A Protein by Using PtNP Modified Electrode

AbstractThe present study reports the optimisation of electrochemical deposition parameters for platinum nanoparticles (PtNPs) on (Indium‐tin‐oxide) surface. PtNPs were electrochemically deposited on APTES (3‐Aminopropyl) triethoxysilane) modified ITO surface to prepare working electrode (PtNP/APTES/ITO). This electrode is further used to fabricate immunoelectrode for detection of SAA biomarker (APO‐SAA) by SAA specific antibodies (SAA Ab) which are immobilised by SAM on the surface of PtNP/APTES/ITO to fabricate SAA‐Ab/PtNP/APTES/ITO immunoelectrode. Characterization of prepared immunoelectrode is done by electrochemical characterization techniques like Differential Pulse Voltammetry (DPV), Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscopy (SEM). Characterization by electrochemical techniques reveal that SAA‐Ab/PtNP/APTES/ITO immunoelectrode can detect Serum Amyloid A protein (SAA) when 10 μl of it (from initial concentration of 10 fg/ml to 106 fg/ml) is poured on immunoelectrode and kept for 10 minutes. Linearity equation is obtained and the LOD is found to be 8.22 fg/ml by applying equation 3σ/sensitivity.

Stable, reproducible, and binder-free gold/copper core–shell nanostructures for high-sensitive non-enzymatic glucose detection

The core–shell non-enzymatic glucose sensors are generally fabricated by chemical synthesis approaches followed by a binder-based immobilization process. Here, we have introduced a new approach to directly synthesis the core–shell of Au@Cu and its Au@CuxO oxides on an FTO electrode for non-enzymatic glucose detection. Physical vapor deposition of Au thin film followed by thermal annealing has been used to fabricate Au nanocores on the electrode. The Cu shells have been deposited selectively on the Au cores using an electrodeposition method. Additionally, Au@Cu2O and Au@CuO have been synthesized via post thermal annealing of the Au@Cu electrode. This binder-free and selective-growing approach has the merit of high electrooxidation activity owing to improving electron transfer ability and providing more active sites on the surface. Electrochemical measurements indicate the superior activity of the Au@Cu2O electrode for glucose oxidation. The high sensitivity of 1601 μAcm−2 mM−1 and a low detection limit of 0.6 μM are achieved for the superior electrode. Additionally, the sensor indicates remarkable reproducibility and supplies accurate results for glucose detection in human serums. Moreover, this synthesis approach can be used for fast, highly controllable and precise fabrication of many core–shell structures by adjusting the electrochemical deposition and thermal treatment parameters.

ElectroLeaching-ElectroChemical Deposition (EL-ECD) of gold and palladium in a deep eutectic solvent (DES)

Precious metals (PM) refining from E-waste recycling are based on hazardous hydrometallurgical processes, including cyanide leaching for gold or aqua regia leaching for palladium, which generates an important wastewater production. In this paper, we present an electrochemical process, based on low viscous deep eutectic solvents ChCl:EG 1:2 and ChCl:EG 1:3. Au and Pd electrochemical leaching and deposition parameters, but also gold and palladium speciation were studied. A one-step ElectroLeaching-Electrochemical Deposition Process (EL-ECD) in a single cell is proposed with high faradic yield of metal recovery. This process avoids electrolyte degradation and is advantageous to limit solvent losses and workers exposition.

Mini‐pillar Based Multi‐channel Electrochemical Platform for Studying the Multifactor Silver Electrodeposition

AbstractHere, we demonstrated a mini‐pillar based multi‐channel electrochemical platform that can efficiently adjust multiple electrochemical deposition parameters in the microdroplet arrays to control and predict the final structures of silver nanomaterials. Each mini‐pillar is capable of anchoring microdroplet to form a separate microreactor, and the electrodes are integrated to achieve a multi‐channel electrochemical electrodeposition platform. We systematically investigated the multiple deposition parameters of silver nanostructures and summarized the relevant experience of electrochemical silver deposition to guide silver nanostructure preparation. Such the mini‐pillar based microdroplet platform provides an approach for further high‐throughput and intelligent nanomaterial fabrication.

Copper Electrodeposition in High Aspect Ratio Mesoscale Through-Silicon Vias: Scaling from Die Level to Wafer Level Plating

Three-dimensional (3D) microsystem integration offers solutions for improved device functionality, increased bandwidth per volume, simplified design and assembly, and system miniaturization. Through-silicon vias (TSVs) are a key technology for incorporating devices into 3D integration schemes. Microelectromechanical systems (MEMS) applications often utilize full thickness silicon substrates, creating a need for mesoscale TSVs (> 0.5 mm thick) at high aspect ratios (> 5:1) to facilitate demands of increased interconnect density. Copper (Cu) is a preferred material for TSV filling because of its high electrical and thermal conductivity and can be deposited through electrochemical deposition (ECD) to fill high aspect ratio features. Although Cu ECD has been historically performed using three additive systems, recent work has demonstrated that Cu deposition can be achieved in a simplified CuSO4-H2SO4 electrolyte system with only a single suppressor additive and halide salt.[i],[ii] The cyclic voltammetry (CV) scan for this electrolyte exhibits s-shaped negative differential resistance (S-NDR), observed as hysteresis in the CV voltage-current relationship between forward and reverse scans. Hysteretic voltammetry indicates bifurcating behavior in the electrolyte system, where bottom-up filling is possible in the vias, while the field surface remains passivated. In systems with limited suppression, performing ECD with a sustained potential leads to localized Cu deposition at specific depths within the vias. An increasingly negative potential waveform can be implemented to progressively move deposition vertically through the vias. Achieving a bottom-up, void-free fill with these additive-based electrolytes is typically performed through potentiostatic plating with a reference electrode. Scaling these processes from die level plating experiments, in a small electrochemical cell, to a production-scale full-wafer plating tool requires development of a current-controlled plating regime, because production tools are not equipped with reference electrodes. Furthermore, the developed plating process cannot be highly sensitive to sample rotation rate, because vias at various radial positions across a wafer move at different speeds. In this work, we describe the development of a current-controlled deposition process for bottom-up, void-free filling and further scale this plating process from 1 cm2 sample sizes to a full 150 mm diameter wafer.Voltage-controlled ECD parameters were first established with die level plating experiments. This voltage-controlled process was used to derive a current-controlled ECD procedure, which was followed by sample size scaling experiments and rotation rate studies. The TSV geometries for these experiments had a 10:1 aspect ratio, with via diameters of 62.5 µm, etched into a 625 µm thick silicon substrate. These vias were successfully filled with a potential stepping regime in which the voltage started at -500 mV (MSE) and was gradually incremented to -560 mV (MSE) using -10 mV steps. Time duration at each potential ranged from 2 to 5 hours to achieve a void-free fill. During these voltage-controlled Cu deposition experiments, the resulting current was measured. Subsequent plating experiments were executed by applying current, as opposed to voltage, to mimic the measured current values, and this current-controlled ECD process also achieved void-free filling. Figure 1 shows the development process from voltage-controlled to current-controlled ECD and corresponding mechanical cross sections. As shown in the sample cross sections, these electroplating processes result in fully suppressed deposition on the field area, even though the field is part of the total conducting surface. It was hypothesized that current density scales with via area, as opposed to total conductive surface area; therefore, scaling experiments were performed to understand the relationship between applied current density, total conductive surface area, and active via area. Additionally, with a wafer rotating about its center, solution replenishment within each via is dependent on its radial position. To understand the dependence on solution replenishment and applied bias in a given electrolyte, a series of investigations were performed on samples rotated at different rates. This work presents the results of these studies for establishing a wafer level plating process for 10:1 aspect ratio TSVs. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. SAND2020-5515 C [i] D. Josell and T. P. Moffat, Journal of The Electrochemical Society, 165 (2) D23-D30 (2018). [ii] L. A. Menk, D. Josell, T. P. Moffat, E. Baca, M. G. Blain, A. Smith, J. Dominguez, J. McClain, P. D. Yeh, and A. E. Hollowell, Journal of The Electrochemical Society, 166 (1) D3066-D3071 (2019). Figure 1

Bottom-up Copper Electrodeposition in 20:1 Aspect Ratio, 20 Μm Pitch through Silicon Vias

Heterogeneous integration (HI) offers a path to increase bandwidth density and reducing power consumption per area for advanced microelectronic systems by minimizing fan-in/out structures and reducing parasitics. To achieve state-of-the-art areal bandwidth density, 3D HI is required with through silicon vias (TSVs) with extremely tight interconnect pitches (< 50 µm) and high aspect ratios. Fabrication and fill of these proposed TSVs pose significant challenges including substrate thinning, high aspect ratio deep reactive ion etching (DRIE), conformal thin film deposition to deposit insulating layers as well as seed metals for electrodeposition, and void-free fill of the TSVs. Here, we target an interconnect pitch of 20 µm and TSV diameter of 5 µm. At these dimensions, DRIE lag limits the TSV depth to 100 µm. The TSVs are integrated using a via-last scheme with atomic layer deposition (ALD) Al2O3 as the insulating liner and ALD Pt serving as both the barrier and electrochemical deposition (ECD) seed liner. In this work, we describe the integration scheme for these high density TSVs and focus on the ECD process for achieving a void-free fill with Cu as well as characterization approaches using focus ion beam (FIB) cross sectioning.Recent work on Cu ECD has demonstrated the efficacy of a two-additive acid sulfate electrolyte system based on a chemistry exhibiting a S-shaped negative differential resistance voltammogram1. The electrodeposition system presented is a 1.0 mol/L CuSO4 – 0.5 mol/L H2SO4 acid sulfate electrolyte containing a polyether surfactant and halide additive which promotes a bottom-up Cu growth profile via positive feedback between localized disruption of adsorbed polyether-halide layer and metal deposition. This electrolyte has been applied to potentiostatic filling of a variety of geometries with both micro-scale1 and mm-scale2 TSVs as well as current controlled bottom-up filling from a conformally conductive seed metal3. This system relies on fine tuning of applied bias, adsorbate concentrations, convection, and deposition time to ensure a bottom-up deposition regime is maintained in a particular via geometry.Previous work developed parameters for filling 600 µm deep 5:1 aspect ratio TSVs and the same parameters were applied to 600 µm deep 10:1 aspect ratio TSVs with drastically different filling results.2 In this work, we further adjust the relevant ECD parameters to fill 20:1 aspect ratio TSVs that are 100 µm deep.In fine pitch, high aspect ratio ECD, characterization of the deposited fill profile is important and is difficult to obtain using mechanical cross-sectioning. Here, we use a characterization approach which relies on focused ion beam (FIB) cross-sectioning rather physical grinding and polishing. The FIB mills into the surface of the sample at a 38º angle with respect to the surface of the sample while the electron beam collects a series of images looking down at the sample, as shown in Figure 1.The series of images collected throughout the FIB milling process are then reconstructed to generate a cross-sectional image. FIB cross-sectioning is also used to provide granular detail about deposition morphology and grain size of the ECD Cu that can be lost during mechanical cross-sectioning. Figure 2, shows a top down scanning electron microscopy image of the TSV sample after milling at 38º and the resulting reconstructed cross-sectional image. T. P. Moffat and D. Josell, J. Electrochem. Soc., 159, D208 (2012).L. A. Menk, D. Josell, T. P. Moffat, E. Baca, M. G. Blain, A. Smith, J. Dominguez, J. McClain, P. D. Yeh, and A. E. Hollowell, Journal of the Electrochemical Society, 166 (1) D3066-D3071 (2019).L. A. Menk, E. Baca, M. G. Blain, J. McClain, J. Dominguez, A. Smith, and A. E. Hollowell, Journal of the Electrochemical Society, 166 (1) D3226-D3231 (2019) Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. This work was funded by the DARPA Photonics in the Package for Extreme Scalability (PIPES) program under award number HR001119S0004. The views, opinions, and/or findings expressed are those of the author(s) and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government. Figure 1

Novel 3-D urchin-like Ni– Co–W porous nanostructure as efficient bifunctional superhydrophilic electrocatalyst for both hydrogen and oxygen evolution reactions

Fabrication of an electrocatalyst with remarkable electrocatalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is important for the production of hydrogen energy. In this study, Ni–Co–W alloy urchin-like nanostructures were fabricated by binder-free and cost-effective electrochemical deposition method at different applied current densities and HER and OER electrocatalytic activity was studied. The results of this study showed that the microstructure and morphology are strongly influenced by the electrochemical deposition parameters and the best electrocatalytic properties are obtained at the electrode created at the 20 mA.cm−2applied current density. The optimum electrode requires −66 mV and 264 mV, respectively, for OER and HER reactions for delivering the 10 mA cm−2 current density. The optimum electrode also showed negligible potential change after 10 h electrolysis at 100 mA cm−2, which means remarkable electrocatalytic stability. In addition, when this electrode used as a for full water splitting, it required only 1.58 V to create a current density of 10 mA cm−2. Such excellent electrocatalytic activity and stability can be related to the high electrochemical active surface area, being binder-free, high intrinsic electrocatalytic activity and hydrophilicity. This study introduces a simple and cost-effective method for fabricating of effective electrodes with high electrocatalytic activity.

An investigation of the effect of pulse electrochemical deposition parameters on morphology, hardness and corrosion behaviour in the marine atmosphere

ABSTRACTCorrosion is one of the major problem that we encounter in our society. Engineering the surface properties of metallic materials are very crucial in corrosion protection. Pulse electrochemical deposition with square wave has successfully been applied to deposit copper from acidic vitriol electrolyte. The influence of the pulse parameter and hardness of the electrodeposits were investigated in depth. Based on the analysis of the microstructure the pulsed electrodeposited copper in 3.5% NaCl solution was studied using potentiodynamic polarisation and electrochemical impedance spectroscopy. Nanoindentation, Scanning electron microscopy and X-ray diffraction studies revealed an increase in hardness and microstructural arrangement respectively with duty cycles. An appreciable increase in corrosion resistance was obtained at high duty cycles and optimised average current density, as indicated by gravimetric and electrochemical methods conducted under flow conditions.

One Step Electrode Fabrication for Direct Electron Transfer Cholesterol Biosensor Based on Composite of Polypyrrole, Green Reduced Graphene Oxide and Cholesterol Oxidase

AbstractA simple single‐step fabrication of a novel biocomposite electrode was used for cholesterol sensing through direct electron transfer. The bio‐composite was prepared by polypyrrole, green reduced graphene oxide (gRGO) and cholesterol oxidase (ChOx). The graphene oxide (GO) was “green” reduced, with the Paederia foetide (PFL) plant extract at 60 °C to improve its biocompatibility. The adherence of gRGO to the electrode surface was improved through its co‐deposition during electro‐polymerization of pyrrole. Interestingly, the enzyme ChOx also could be immobilized during this co‐deposition process, resulting in one step biosensor fabrication. The optimization of electrochemical deposition parameters on glassy carbon electrode for this enzymatic bioelectrode (ChOx‐gRGO‐PPy/GCE) has resulted in excellent sensitivity (1095.3 μA mM−1 cm−2), wide linear range (0.01–6 mM), and low detection limit (3.78 μM) of cholesterol. Also, the Dubinin‐Radushkevitch (D−R) adsorption study revealed the occurrence of physisorption (ϵ=3.35) process in this bioelectrode, confirming diffusion‐controlled reaction. Reproducibility of electrodeposition procedure, impeccable selectivity in the presence of interferrants, repeatability for multiple use and long‐term stability for practical use were also ensured. This could be used to construct the cost‐effective device for cholesterol diagnosis.

(Invited) Compact Telluride Films Prepared By Electrochemical Deposition and Their Applications for Integrated Micro- Thermoelectric Devices

Thermoelectric materials of Tellurium (Te) and its based compounds (binary Bi2Te3 and Sb2Te3, or ternary Bi2(TexSe1-x)3 and (BixSb1-x)2Te3) as the n-type and p-type materials, respectively), possess the best thermoelectric figure-of-merit in the temperature range of room temperature up to 200 °C. Preparing thick and compact Telluride films with thickness in the range of tens of micrometers by electrochemical deposition (ECD) allows to realize on-chip integration of thermoelectric devices. ECD offers additional advantages regarding up-scalability, cost effective processing, and compatibility with microelectromechanical systems processing. In our work, we firstly put efforts on growing thick and compact Telluride films for both n- and p- type materials by ECD technique. Secondly, various measurement techniques (in-situ and ex-situ) are utilized to characterize the thermoelectric transport properties, which are further analyzed to tune the ECD parameters to optimize the material properties. Thirdly, integrated micro- thermoelectric coolers (µTECs), with a leg pair packing density over 5000/cm2 are successfully fabricated by combining conventional techniques of ECD and photolithography. Long-term performance and stability of the as-fabricated µTECs are systematically studied using a CCD-based thermoreflectance imaging setup. Finally, model simulations based on finite-element method show consistency with the experimental results, indicating high quality thermoelectric materials (for both n and p legs) and negligible contact resistances in the as-fabricated µTECs.

3D mossy structures of zinc filaments: A facile strategy for superamphiphobic surface design

The superamphiphobic surfaces with extreme repellency to liquids are very attractive in many fields, but their fabrication processes are always low effective and expensive. So it is still a challenge to create the superamphiphobic surfaces by simple, time saving and universal method. In this work, the mossy zinc (Zn) filaments, a promising re-entrant structure, was rapidly constructed on various metal surfaces by electrochemical deposition approach. After modification by 1H,1H,2H,2H- perfluorodecyltrichlorosilane (PFDTCS), the Zn@PFDTCS coating exhibited superamphiphobicity in air. The correlation between the morphology of Zn filaments and electrochemical deposition parameters has been studied. The superamphiphobic surface with contact angle higher than 154°, sliding angle lower than 5° and adhesive force lower than 0.043 mN to water and hexadecane was obtained, when the current density was 1.78 A ·dm−2, the mass fraction of zinc was 0.71 wt% and the deposition time was 40 min. Furthermore, the Zn@PFDTCS 2D-meshes were used to collect oil droplets under water and cut water droplet in oil due to their superoleophilicity under water and superhydrophobicity under oil. We anticipated that the simple and rapid method guides the design of perfect artificial superamphiphobic surfaces in practical application.

Influence of deposition temperature on the properties of hydroxyapatite obtained by electrochemical assisted deposition

Surface functionalization of pure titanium (cp-Ti) with hydroxyapatite (HAp) was successfully achieved by means of electrochemical deposition (ED) in a solution containing calcium nitrate and ammonium dihydrogen phosphate. The aim of this study is to evaluate the influence of the deposition temperature on the elemental and phase composition, chemical bonds, morphology, and in vitro electrochemical behaviour in biological simulated media (simulated body fluid - SBF). The roughness and wettability of the developed coatings are also investigated. By increasing the deposition temperature from 50°C to 75°C, the HAp coatings present a well-crystalized structure, denser and a nobler behaviour in terms of electrochemical behaviour in SBF at 37°C. Also, by increasing the deposition temperature from 50°C to 75°C, the contact angle has decreased from 76.1° to 27.4°, exhibiting a highly hydrophilic surface. Taking into consideration all the obtained data, electrodeposition of HAp at 75°C was found preferable when compared to 50°C. The characteristics of the HAp coatings can be easily adjusted by optimizing the electrochemical deposition parameters and/or controlling specific features like pH, temperature, or ionic concentration of electrolyte, etc.

Optimization of performance and stability of quantum dot sensitized solar cells by manipulating the electrical properties of different metal sulfide counter electrodes

Fabrication of low cost and high catalytic active counter electrode (CE) for quantum dot sensitized solar cells is one of the dynamic ways to enhance the performance of quantum dot solar cell. In this investigation, different CE materials such as copper sulfide (Cu2S), cobalt sulfide (CoS) and nickel sulfide (NiS) were deposited on fluorine doped tinoxide (FTO) glass and brass plate by single step electrophoretic deposition technique and solar cell performance and stability of three different CEs were tested. Electrochemical deposition parameters were optimized for the optimization of CEs performance. Electrical properties of Cu2S, CoS and NiS CEs were investigated by electrochemical impedance spectroscopy and electrical properties were compared with the observed solar cell performances and stability. Of the tested CEs materials, enhanced solar cell performance was observed with Cu2S CE than the CoS or NiS CEs while brass substrae was found to be a better substrate than FTO for these CE materials. The optimized Cu2S/brass plate CE showed current density of (Jsc) 17.9mA.cm−2, open circuit voltage of (Voc) 494.5mV, fill factor of (FF) 59.0% and efficiency of 5.2% with the solar cell fabricated with PbS/CdS q-dot anode. While Cu2S/FTO glass plate CE showed Jsc of 16.1mA.cm−2, Voc of 489.4mV, FF of 52.9% and efficiency of 4.2% of with the same q-dot anode. A higher electrocatalytic activity together with the lower charge transfer resistance (Rct) and good inter-connected Cu2S particles on brass electrodes were found to be the major CE properties that decides the performance of CE.

Influence of electrochemical deposition parameters on capillary performance of a rectangular grooved wick with a porous layer

A wick is a key component of two-phase heat transfer devices. To balance conventional conflicting requirements between permeability and capillary pressure performance, a rectangular grooved composite wick combined with a porous deposition layer was fabricated on a copper plate using a combined technology of planing, electrochemical deposition and heat treatment. The permeability of this composite wick was tested experimentally by a forced liquid flow method to investigate the effect of electrochemical deposition parameters. Deposition current density was shown to affect permeability more intensely than deposition time. To overcome the difficulty of porosity measurement, a modified capillary performance parameter K/(AiwReff) instead of conventional K/Reff was proposed to evaluate the comprehensive capillary performance of the composite wick. In addition, an infrared (IR) thermal imaging method was employed to investigate capillary rising height and velocity, using ethanol as the test liquid. The influence of deposition parameters and wick types on the values of parameter K/(AiwReff) was discussed. The results show that there is an optimal value of both deposition time and current density to maximize capillary performance of the composite wick. Comparative studies show that a composite wick features a better capillary performance with proper fabrication parameters than a plane-deposition or its preformed smooth grooved wick.

Electrochemical deposition of mineralized BSA/collagen coating

In this work, mineralized collagen coatings with different loading quantity of bovine serum albumin (BSA) were prepared via in situ electrochemical deposition on titanium substrate. The microstructure and BSA loading quantity of the coatings could be controlled by the electrochemical deposition parameters, such as deposition potential, BSA concentration and its adding sequence in the electrolyte. The BSA loading quantity in the coatings was obtained in the range of 0.0170–0.173mg/cm2, enhancing the cell adhesion and proliferation of the coatings with the simultaneous release. The distinct release behaviors of BSA were attributed to their gradient distribution with different mineralization degrees, which could be adjusted by the deposition process. These results suggest that in situ electrochemical deposition is a promising way to incorporate functional molecules into the mineralized collagen coatings and the mineralized BSA/collagen coatings are highly promising for improving the rhBMP-2 loading capability (1.8-fold).

Formation and Characterization of Hydroxyapatite Coating Prepared by Pulsed Electrochemical Deposition

Abstract Hydroxyapatite coatings were prepared on magnesium alloy AZ91D by pulsed electrochemical deposition. The effects of electrochemical deposition parameters such as pulsed voltage, electrochemical deposition time and electrolyte additive on the morphology, the microstructure, the composition, the coating thickness and electrochemical properties were tested. The results show that at 110 V, the coating with lower porosity, more homogeneous surface and nanometer particles can be obtained, which also has higher XRD diffraction peaks. The morphology and the microstructure of hydroxyapatite particles of the samples prepared in Ca-P electrolyte with NaNO 3 and H 2 O 2 addition at 110 V are optimized. The corrosion resistance of the prepared coating is enhanced in potentiodynamic polarization and electrochemical impedance tests. Moreover, immersion test results indicate that such a coating is beneficial to hydroxyapatite formation and enhancing the bioactivity in simulated solution.

Influences of the main anodic electroplating parameters on cerium oxide films

Abstract Cerium oxide thin films were fabricated onto 316 L stainless steel via a potentiostatically anodic electrodeposition approach in the solutions containing cerium(III) nitrate (0.05 M), ammonia acetate (0.1 M) and ethanol (10% V/V). The electrochemical behaviors and deposition parameters (applied potential, bath temperature, dissolving O 2 and bath pH) have been investigated. Results show that, the electrochemical oxidation of Ce 3+ goes through one electrochemical step, which is under charge transfer control. The optimum applied potential for film deposition is 0.8 V. Bath temperature plays a significant effect on the deposition rate, composition (different colors of the film) and surface morphology of the deposits. Due to the hydrolysis of Ce 3+ , cerous hydroxide is facility to form when the bath temperature is higher than 60 °C. The electroplating bath pH is another key role for the anodic deposition of cerium oxide thin films, and the best bath pH is around 6.20. N 2 or O 2 purged into the bath will result in film porosities and O 2 favors cerium oxide particles and film generation.