Pulsed Electrochemical Deposition Research Articles

Effect of employing ultrasonic waves during pulse electrochemical deposition on the characteristics and biocompatibility of calcium phosphate coatings

In the present work, we investigated the effect of employing ultrasonic waves during pulse electrochemical deposition on surface topography, chemical composition and biocompatibility of calcium phosphate (Ca-P) coatings. The SEM and 3D AFM images showed that the anodized titanium surface was covered with the uniform and refined size of plate-like Ca-P crystals, when the ultrasonic treatment of the electrolyte with power of 60 W was carried out during deposition. In contrast, for the Ca-P; 0 W coating applied under only the magnetic stirring of the electrolyte, the microstructure was non-uniform and some Ca-P crystals with the larger size were randomly observed in different regions, causing a rougher surface. The FTIR results also revealed that employing the ultrasound increases the deposition of a coating involved in only the most stable Ca-P phase of carbonated hydroxyapatite (CHA). However, in the absence of ultrasound, besides the prominent phase of CHA, some less stable Ca-P phases like octa calcium phosphate (OCP) and brushite were also formed in the Ca-P; 0 W coating. The Ca-P; 60 W coating showed the higher ability for apatite biomineralization after a 7-day immersion in the simulated body fluid (SBF). This coating also provided a better surface for the cellular activity, as compared to the Ca-P; 0 W coating.

Effects of complexing agents on electrochemical deposition of FeSxOy in ZnO/FeSxOy heterostructures

Heterostructures which consist of ZnO and FeSxOy were deposited via electrochemical deposition (ECD) for application to solar cells. Galvanostatic ECD was used in FeSxOy deposition with a solution containing 100 mM Na2S2O3 and 30 mM FeSO4. To alter the film properties, L(+)-tartaric acid (C4H6O6) and lactic acid [CH3CH(OH)COOH] were introduced as the complexing agents into the FeSxOy deposition solution. Larger film thickness and smaller oxygen content were obtained for the films deposited with the complexing agents. ZnO was deposited on FeSxOy by two-step pulse ECD from a solution containing Zn(NO3)2. For the ZnO/FeSxOy heterostructures fabricated with/without complexing agents, rectifying properties were confirmed in the current density–voltage (J–V) characteristics. However, photovoltaic properties were not improved with addition of both complexing agents.

Functional design of electrolytic biosensor

A novel amperometric biosensbased on conjugated polypyrrole (PPy) deposited on a Pt modified ITO (indium tin oxide) conductive glass substrate and their performances are described. We have presented a method of developing a highly sensitive and low-cost nano-biosensor for blood glucose measurements. The fabrication method proposed decreases the cost of production significantly as the amount of noble metals used is minimized. A nano-corrugated PPy substrate was developed through pulsed electrochemical deposition. The sensitivity achieved was 325 mA/(Mcm2) and the linear range of the developed sensor was 50-60 mmol/l. Then the application of the electrophoresis helps the glucose oxidase (GOx) on the PPy substrate. The main reason behind this high enzyme loading is the high electric field applied across the sensor surface (working electrode) and the counter electrode where that pushes the nano-scale enzyme particles floating in the phosphate buffer solution towards the substrate. The novel technique used has provided an extremely high sensitivities and very high linear ranges for enzyme (GOx) and therefore can be concluded that this is a very good technique to load enzyme onto the conducting polymer substrates.

Mo(SxOy) thin films deposited by electrochemistry for application in organic photovoltaic cells

In this study, Mo(SxOy) thin films were deposited onto fluorine doped tin oxide (FTO) using pulsed electrochemical deposition method. It is shown by scanning electron microscopy, energy-dispersive spectroscopy and X-ray photoelectron spectroscopy that after water cleaning the deposited Mo(SxOy) film corresponds to a hybrid layer MoSx:MoO3. This hybrid is used as anode buffer layer (ABL) in planar organic photovoltaic cells (OPVCs) based on the couple copper-phthalocyanine/fullerene. It is shown that it is necessary to proceed to a soft annealing-5 min at 150 °C- of the anode FTO/Mo(SxOy) to clean the ABL surface in order to obtain efficient contact with the organic material. The OPVC with the optimum Mo(SxOy) thickness, 12 nm, showed a power conversion efficiency, PCE = 1.41% under an illumination of AM1.5, which is 12% higher than that achieved with a simple MoO3 ABL. This improvement is attributed to the fact that using a hybrid MoS2:MoO3 ABL allows to combine the advantages of its both constituents. The MoSx blocks the electrons, while the high work function of MoO3 induces a high hole extraction efficiency at the interface electron donor/anode.

Atomic platinum layer coated titanium copper nitride supported on carbon nanotubes for the methanol oxidation reaction

In this study, a novel low-Pt core-shell catalyst is successfully prepared by depositing ultrathin Pt layer on the carbon nanotubes supported titanium nitride nanoparticles (TiN@Pt/CNTs) via a facile pulse electrochemical deposition approach. The catalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), High-angle annular dark field (HAADF) and energy-dispersive spectrometer (EDS) elemental mapping, X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. The results confirm the core-shell structure of the prepared TiN@Pt/CNTs catalyst. More importantly, the catalyst exhibits superb mass activity and durability for the methanol oxidation reaction (MOR) than that of the commercial JM Pt/C catalyst. Later experiments data demonstrate that the activity and stability of the catalyst can be further enhanced via copper doping, which results from the modified electronic structure of the Pt atoms and the synergistic effects of the core-shell structure.

In situ construction of Ir@Pt/C nanoparticles in the cathode layer of membrane electrode assemblies with ultra-low Pt loading and high Pt exposure

Abstract A novel membrane electrode assemblies (MEAs) with ultra-low Pt loadings and high Pt exposure in the cathode layer is prepared by spraying Ir/C catalyst ink on the membrane surface to form a substrate layer, followed by in situ pulse electrochemical deposition of a Pt shell layer on the Ir core nanoparticles in the substrate layer. It makes the Pt loadings on cathode lower to 0.044 mg/cm 2 . In our system, the MEA with our novel cathode exhibits excellent performance in a H 2 /air single fuel cell, which is comparable to that of the MEA prepared with commercial Pt/C catalyst (Johnson Matthey 40% Pt) with Pt loadings of 0.1 mg/cm 2 . The electrode with core–shell structured catalysts is characterized by X-ray diffraction, X-ray photoelectron spectroscopy, EDS line-scan, and scanning transmission electron microscopy. Based on the characterization results, it is found that the Pt is highly dispersed on the Ir NPs, and the electronic feature of Pt at shell layer can be tuned by the Ir core particle. Furthermore, the DFT calculation results also reveal the interaction between Pt at shell layer and Ir core. This work may provide a novel pathway to realize low Pt and high Pt utilization in low temperature fuel cells.

Effects of Electrolyte Concentration on Formation of Calcium Phosphate Films on Ti–6Al–4V by Electrochemical Deposition.

Nano-sized calcium phosphate film was formed on Ti–6Al–4V alloy using simple electrochemical deposition. Pre-treatment of Ti–6Al–4V alloy was carried out by galvanostatic treatment step which acted as anchorage for growth of the hydroxyapatite during subsequent pulsed electrochemical deposition process at 40 and 85 °C. The phase and morphologies of deposited calcium phosphate were influenced by the electrolyte temperature and electrolyte ratio (Ca/P). The nano needle-like precipitates were formed under 1.67 Ca/P ratio in solution. The needle-like deposits were transferred to the plate-like precipitates in the case of Ca-deficient or Ca-rich electrolyte.

Nanosized Hydroxyapatite Precipitation on the Ti—30Ta—xHf Alloys.

In this study, we prepared hydroxyapatite (HAp) layer on the alkali treated Ti–30Ta–xHf alloys using electrochemical deposition method. Ti–30Ta–xHf alloys was anodized in 5 M NaOH solution at 0.3 A for 10 min. Alkali treated Ti–30Ta–xHf surface formed by anodization step which acted as templates and anchorage for growth of the HAp during subsequent pulsed electrochemical deposition process at 85 °C. The phase and morphologies of deposited HAp layer were affected by the Hf contents of Ti–30Ta–xHf alloys. The nano-scale rod-like HAp layer was formed on untreated Ti–30Ta–xHf alloys with partially low crystallinity. In the case of alkali treated Ti–30Ta–xHf, nano-sized needle-like layers were transferred to nano-flake surface and denser morphology as Hf content increased.

전기화학증착조건에 따른 임플란트 표면의 칼슘 포스페이트 코팅막의 특성

A simple electrochemical deposition method has been progressed to form a nano-phase hydroxyapatite (CaSUB10/SUB(PO₄)SUB6/SUB(OH)₂, HAp) deposited on a BN 5010SUP®/SUP dental implant. Pre-treatment of BN 5010SUP®/SUP dental implant was carried out by galvanostatic treatment step which acted as anchorage for growth of the calcium phosphate (CaP) during subsequent pulsed electrochemical deposition process. Electrochemical deposition of CaP was conducted in various condition. The phase and morphology of deposits calcium phosphate were influenced by the applied voltage, electrolyte temperature, and electrolyte ratio (Ca/P). The nano needle-like precipitates formed under 1.67 Ca/P ratio in solution at 85 ℃. The needle-like deposits transferred to the plate-like precipitates in the case of calcium (Ca) ion concentration and applied voltage. The results of in corrosion and dissolution test indicated that the HAp deposited implants acted as bio-active materials.

Ultra-low Pt loading catalyst layers prepared by pulse electrochemical deposition for PEM fuel cells

We report the production of efficient, ultra-low Pt loading catalyst layers on fuel cell electrodes via pulse potential deposition (PPD) from a H2Pt(OH)6 plating solution. We show that by optimizing the off time in the PPD pulse sequence, it is possible to deposit very small, crystalline Pt nanoparticles with narrow size distribution (1.36 ± 0.360 nm) on amorphous carbon supports. Electrodes fabricated from these high surface area electrocatalysts display increased fuel cell performance compared to commercial electrodes with up to an order of magnitude less Pt. The improved performance of our electrodes is attributed to a combination of the optimized size of the deposited nanoparticles as well as the decreased thickness of the catalyst layer. In our deposited electrodes the catalyst layers are very thin (<10 μm) and as a result achieve up to twelve times the gravimetric power of commercial electrodes.

Biocompatibility of hydroxyapatite coatings deposited by pulse electrodeposition technique on the Nitinol superelastic alloy

The present study deals with pulse electrochemical deposition of HA on NiTi alloy and in vitro evaluation of coatings. At first step, a thermo-chemical surface modification process was applied to control the Ni release of the alloy. The electrochemical deposition of CaP coatings was examined at both dilute and concentrated solutions. The morphology and the composition of coatings were studied using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Plate like and needle like morphologies were formed for dilute and concentrated solution respectively and HA phase was formed by increasing the pulse current density for both electrolyte. The thickness of the samples was measured using cross sectioning technique. Fibroblast cell culture test on the coated samples revealed that the HA coating obtained by dilute solution shows the best biocompatibility. Also, MTT assay showed the highest cell density and cell proliferation after 5days for the HA coating of dilute solution. The contact angle of samples was measured and the coated samples showed a hydrophilic surface. Soaking the sample in SBF revealed that the crystallization rate of calcium-phosphate compounds is higher on the plate like HA coating as compared to the needle like morphology. The P release of the HA coated samples was measured in a physiological saline solution and the results show that the ions releasing in the plate like coating are less than the needle like coating. It seems that the stability of the plate like coating in biological environments is responsible for the better biocompatibility of the coating.

Three-step pulse electrochemical deposition of FeSxOy thin films and their characterization

Three-step pulse electrochemical deposition was used to deposit FeSxOy thin films on indium–tin-oxide-coated glass substrates at room temperature from solution containing Na2S2O3 and FeSO4. The deposition was conducted under two different potential shifts direction (condition A: from negative to positive and condition B: from positive to negative) with intermediate potential V2 variation. All the deposited films were amorphous. In Raman measurements, peaks attributed to marcasite and Fe1+xS were observed. The O/Fe ratio is larger than unity. The films deposited under condition A with an intermediate potential V2 = −0.6 V and condition B with V2 = −0.4 V showed a band gap which is estimated around 2.3–2.45 eV, larger than literature value of Fe2O3 (2.1 eV). In the photoelectrochemical measurement, nearly intrinsic behavior was confirmed.

Photodegradation performance and mechanism of 4-nonylphenol by WO3/TiO2 and TiO2 nanotube array photoelectrodes

ABSTRACTTiO2 Nanotube arrays (TNA) and WO3-coated TNA photoelectrodes were fabricated using an in situ anodization and pulse electrochemical deposition technology. The performance of the TNA photoelectrodes in the photocatalytic (PC) and photoelectrocatalytic (PEC) degradation of 4-nonylphenol (4-NP) was investigated. The effects of the initial pH and the anions on the degradation rates and reaction mechanism of 4-NP were studied by the photoluminescence (PL) spectra and electrochemical impedance spectra (EIS). The degradation of 4-NP was fitted to a first-order reaction, and the apparent kinetic constants were 1.9 × 10−2 min−1 for TNA photoelectrodes and 2.4 × 10−2 min−1 for WO3/TNA photoelectrodes. When a bias potential of 1.0 V was applied, the values for TNA and WO3/TNA photoelectrodes increased to 2.5 × 10−2 and 3.0 × 10−2 min−1, respectively. The degradation of 4-NP was controlled by a charge-transfer process one. WO3-decorated TNA photoelectrodes could increase the adsorption of 4-NP and promote its degradation. For the TNA and WO3/TNAs photoelectrodes, acid and alkaline solutions could facilitate the formation of hydroxyl radicals, whereas the removal of 4-NP was inhibited. The presence of , Cl−, and has a negative effect on the formation of •OH, so did the removal of 4-NP. For the TNA photoelectrodes, the inhibition effect of on the formation of hydroxyl radicals and the removal of 4-NP was the most serious compared with that of , Cl− and , while for the WO3/TNA photoelectrodes the inhibition effect of on the removal of 4-NP was maximum.

Electrosynthesis of neodymium oxide nanorods and its nanocomposite with conjugated conductive polymer as a hybrid electrode material for highly capacitive pseudocapacitors

Herein, we report for the first time a facile and cost-efficient synthesis of metal oxide nanostructures comprised of nanorods type without the use of any additive. Nd(OH)3 and Nd2O3 nanorods were obtained by ultrasound wave assisted pulse electrochemical deposition in a Nd(NO3)3·6H2O nitrate bath. In addition, the interconnected nanorods were mesoporous leading to large electrochemical active sites for the redox reaction and fast ion transport within the Nd2O3 nanorods. Furthermore, for improving the electrochemical performance of conductive polymer, hybrid POAP/Nd2O3 films have then been fabricated by POAP electropolymerization in the presence of Nd2O3 nanorods as active electrodes for electrochemical supercapacitors. Surface and electrochemical analyses have been used for characterization of Nd2O3 and POAP/Nd2O3 composite films. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance. Prepared composite film exhibited a significantly high specific capacity, high rate capability and excellent cycling stability. Importantly, electrochemical investigation show that POAP/Nd2O3 nanorods composite material has better properties than POAP without Nd2O3 nanorods, suggesting it can be used as supercapacitor electrode material with excellent specific capacitance (379Fg−1) which indicates this material is a promising electrode material for energy storage applications in high-performance pseudocapacitors.

Fabrication of Antibacterial and Antiwear Hydroxyapatite Coatings via In Situ Chitosan-Mediated Pulse Electrochemical Deposition.

Although bioinert titanium has been widely applied in orthopedics and related fields, its usage is limited by its unsatisfying osteoinductivity, anti-infection capability, and wear-resistance. Osteoinductive apatite coating can be fabricated on a titanium surface by electrochemical methods, but this causes bacterial adhesion and poor wear-resistance. On the basis of pulse electrochemical technology, a wear-resistance and antibacterial osteoinductive coating was fabricated through codeposition of hydroxyapatite (HA) and nano-Ag effectuated by the cohybridization ofchitosan (CS) with Ag+ and Ca2+. A composite coating formed with uniformly dispersed spherical nanoparticles was obtained at optimized deposition potential, Ag concentration, and apatite concentration. The nanocomposite coating shows excellent bioinductive activity; it promotes preferential growth on the (002) face, and needle-like ordered arrangement of apatite. Due to the mediation of CS hybridization, a compact structure is achieved in the HA/Ag composite coating which significantly enhances the wear-resistance of the coating and reduces the release of Ca2+ and Ag+. The antibacterial rate of the coating on Escherichia coli and Staphylococcus aureus is up to 99% according to the antibacterial test. In conclusion, a wear-resistant and long-term antibacterial bioactive nanocomposite coating is successfully fabricated on titanium surface through the strategy established in this study.

A promising electrode material modified by Nb-doped TiO2 nanotubes for electrochemical degradation of AR 73

A distinctive SnO2Sb electrode with highly ordered Nb doped TiO2 nanotubes sheet as a new substrate, obtained by NbTi alloy anodization, is prepared by pulse electrochemical deposition for the first time as electrocatalytic oxidation anode for wastewater treatment. The novel electrode has a larger surface area and smaller crystallite particles than conventional SnO2Sb electrodes as obtained from the analysis of scanning electron microscopy and X-ray diffraction. Compared with Ti/SnO2Sb and Ti/TiO2-NTs/SnO2Sb prepared by pulse electrochemical deposition, the electrode modified by NbTiO2-NTs has the higher oxygen evolution potential of 2.29 V (vs. Ag/AgCl), and the lower charge transfer resistance, which decreased by 65% and 79%. The service lifetime of NbTi/NbTiO2-NTs/SnO2Sb is 4.9 times longer than that of Ti/SnO2Sb and 1.9 times longer than that of Ti/TiO2-NTs/SnO2Sb. The new electrode is proved to have an excellent electrochemical oxidation and degradation ability using Acid Red 73 as a target organic pollutant. The AR 73 removal, chemical oxygen demand removal and kinetic rate constant are increased obviously due to the introduction of NbTiO2-NTs. Besides, the energy consumption reduces 37.2% and 31.4% in contrast with Ti/SnO2Sb and Ti/TiO2-NTs/SnO2Sb. Hence, the Ti/SnO2Sb modified by NbTiO2-NTs is a very promising anode material for the electrochemical treatment of dye wastewater.

PEM fuel cell electrode preparation using oxygen plasma treated graphene related material serving as catalyst support for platinum nanoparticles

This work deals with the preparation and investigation of polymer electrolyte membrane fuel cell (PEMFC) electrodes, which are obtained using gas diffusion layers coated with graphene related material (GRM) serving as a catalyst support for platinum nanoparticles. PEMFC electrocatalysts have been prepared by pulsed electrochemical deposition of platinum particles from hexachloroplatinic acid. Prior to GRM decoration with platinum, the graphene structures are functionalized by oxygen plasma treatment. This leads to oxygen containing functional groups on the GRM outer surface, providing an improved hydrophilic behavior, thus favoring the Pt deposition process. Membrane electrode assemblies (MEAs) with the so prepared electrodes are investigated in-situ in our fuel cell test system. Polarization plots (in-situ cell performance) using these MEAs have been tested under different operational conditions.

Next-Generation Multifunctional Electrochromic Devices.

The rational design and exploration of electrochromic devices will find a wide range of applications in smart windows for energy-efficient buildings, low-power displays, self-dimming rear mirrors for automobiles, electrochromic e-skins, and so on. Electrochromic devices generally consist of multilayer structures with transparent conductors, electrochromic films, ion conductors, and ion storage films. Synthetic strategies and new materials for electrochromic films and transparent conductors, comprehensive electrochemical kinetic analysis, and novel device design are areas of active study worldwide. These are believed to be the key factors that will help to significantly improve the electrochromic performance and extend their application areas. In this Account, we present our strategies to design and fabricate electrochromic devices with high performance and multifunctionality. We first describe the synthetic strategies, in which a porous tungsten oxide (WO3) film with nearly ideal optical modulation and fast switching was prepared by a pulsed electrochemical deposition method. Multiple strategies, such as sol-gel/inkjet printing methods, hydrothermal/inkjet printing methods, and a novel hybrid transparent conductor/electrochromic layer have been developed to prepare high-performance electrochromic films. We then summarize the recent advances in transparent conductors and ion conductor layers, which play critial roles in electrochromic devices. Benefiting from the developments of soft transparent conductive substrates, highly deformable electrochromic devices that are flexible, foldable, stretchable, and wearable have been achieved. These emerging devices have great potential in applications such as soft displays, electrochromic e-skins, deformable electrochromic films, and so on. We finally present a concept of multifunctional smart glass, which can change its color to dynamically adjust the daylight and solar heat input of the building or protect the users' privacy during the daytime. Energy can also be stored in the smart windows during the daytime simultaneously and be discharged for use in the evening. These results reveal that the electrochromic devices have potential applications in a wide range of areas. We hope that this Account will promote further efforts toward fundamental research on electrochromic materials and the development of new multifunctional electrochromic devices to meet the growing demands for next-generation electronic systems.

Pulsed electrochemical deposition of nickel oxides on multi-walled carbon nanotubes from EDTA alkaline solutions: a SEM, XPS, and voltammetric characterization

A study regarding the electrodeposition of nickel oxide particles on the activated multi-walled carbon nanotubes from 2 M NaOH solution containing Ni(NO3)2 and EDTA was carried out. The electrodeposition process was carried out using an optimized double-pulse sequence of potentials: E 1 = −0.2 V vs. SCE (t 1 = 0.3 s) and E 2 = 0.7 V vs. SCE (t 2 = 0.03 s). Spectroscopic XPS investigations and SEM analysis were used in order to characterize the surface and morphology of the studied modified electrode. Cyclic voltammetry and chronoamperometry were used in order to evaluate the electrochemical/amperometric performance of the GC/MWCNT-Ni electrode toward the oxidation of some aliphatic alcohols in strong alkaline medium.

Electrochemical fabrication of 2D and 3D nickel nanowires using porous anodic alumina templates

Mechanically stable nickel (Ni) nanowires array and nanowires network were synthesized by pulse electrochemical deposition using 2D and 3D porous anodic alumina (PAA) templates. The structures and morphologies of as-prepared films were characterized by X-ray diffraction and scanning electron microscopy, respectively. The grown Ni nanowire using 3D PAA revealed more strength and larger surface area than has grown Ni use 2D PAA template. The prepared nanowires have a face-centered cubic crystal structure with average grain size 15 nm, and the preferred orientation of the nucleation of the nanowires is (111). The diameter of the nanowires is about 50–70 nm with length 3 µm. The resulting 3D Ni nanowire lattice, which provides enhanced mechanical stability and an increased surface area, benefits energy storage and many other applications which utilize the large surface area.