Constant Potential Deposition Research Articles

Sensitive detection of HSP70 using a current-amplified biosensor based on antibody-loaded PS-AuNPs@Cys/Au modified ITO chip.

A biosensing electrochemical platform for heat shock protein 70 (HSP70) has been developed by integrating a three-electrode indium tin oxide (ITO) on a chip. The platform includes modifications to the reference electrode and working electrode for the detection of HSP70. The new platform is constructed by assembly of HSP70 antibody on PS-AuNPs@Cys/Au indium tin oxide (ITO) electrode to create a high HSP70 sensitive surface. The PS-AuNPs@Cys/Au indium tin oxide (ITO) electrode is obtained by immersing the ITO electrode into the PS-AuNPs@Cys solution and performing constant potential deposition at -1.4V (Ag/AgCl). The PS-AuNPs@Cys/Au film deposited on ITO glass provides a desirable substrate for the immobilization of the HSP70 antibody and improves the loading of antibody between PS-AuNPs@Cys/Au and the electrode resulting in a significant amplification. Under optimal conditions, the fabricated sensor demonstrates a linear range extending from 0.1 ng mL- 1 to 1000 ng mL- 1, with an impressive detection limit of 25.7 pg mL- 1 (S/N = 3). The developed immunoassay method successfully detected the HSP70 content in normal human blood samples and outperformed the ELISA method commonly used for clinical sample analysis.

(Digital Presentation) Construction of a Novel Phosphate Potential Sensor and Its Application

Phosphorus content is one of important indicators in the evaluation of water quality. The level of phosphorus in oilfield water systems not only affects the overall water cycle production system, but excessive phosphorus wastewater entering the environment can cause eutrophication of the water body, as can high levels of ammonia and nitrogen, and leading to rapid growth of algae and thus affecting the balance of the aquatic ecosystem. Therefore, the regulation of phosphorus is of great importance. Phosphorus exists in nature mainly in the form of phosphate, which is currently detected by the traditional spectrophotometric method. As this method requires the addition of a large number of chemical reagents, it is not only complex and time consuming, but also produces a waste solution at the end of the test that can easily cause secondary pollution to the environment. Compared to traditional methods, Ion Selective Electrodes (ISEs) are easier to use, more sensitive, less expensive and do not cause secondary contamination. In conventional ion selective electrode detection systems, liquid contact ion selective electrodes consisting of a polymeric ion selective membrane, an internal filling fluid and an internal reference electrode are susceptible to common variables such as pressure and temperature. There are problems with complex maintenance, leakage and signal calibration. In contrast, all-solid ion-selective electrodes that eliminate the internal filling fluid and internal reference have become a hot research topic for such potential-based sensors. In this thesis, the following research was carried out with the aim of developing a phosphate potentiometric sensor with practical detection capabilities:(1) PANI/ITO electrodes were produced by electrodeposition of polyaniline on ITO conductive glass by constant potential deposition and by ultrasonic peeling. Three oxidation states of PANI/ITO electrodes were prepared at different voltages using phosphoric acid as the doping solution. LBPANI/ITO electrode in the fully reduced state, ESPANI/ITO electrode in the semi-oxidized state and PBPANI/ITO electrode in the fully oxidized state. The response sensitivity and stability of the three electrodes were investigated to determine the optimum doping potential; the response performance of the electrodes was tested for different doping times to determine the optimum preparation time. It is shown that the PBPANI/ITO electrode in the fully oxidized state has the optimum stability and response sensitivity at a doping time of 80 s. The electrode showed good linear response in the range of 1.00x10-5 ~ 1.00x10-1 M, with a response sensitivity of 37.30 dec/mV (R2 = 0.9966) and a detection limit of 10-5.6 M. The response time of the electrode to the solution was around 4 s, and it had good acid-base adaptability (pH 4.0 ~ 8.0). The performance of the prepared PBPANI/ITO electrode as a potentiometric phosphate sensor was also investigated in terms of stability (n = 10, RSD 1.76 %) and lifetime (6 weeks at room temperature), and was successfully used for phosphate detection and analysis in oilfield re-injection water, lake water and tap water samples in real environments with satisfactory results. (2) To further prepare a phosphate potential sensor with a high sensitivity response. We pretreated the home-made cobalt electrode with high pressure anodic oxidation in sodium hydroxide solution to produce a uniform cobalt oxide passivation film on the electrode surface. The sensitivity and stability of the response of the electrode at different pretreatment times were investigated to determine the optimum preparation conditions. The results showed that the pretreated cobalt electrode had a good response in the range of 1.00x10-5 ~ 1.00x10-1 M. The response sensitivity was 67.22 mV dec, R2 = 0.9939 and the detection limit was 10-5.5 M. It was much higher than that of the untreated cobalt electrode. This far exceeded that of the untreated polished cobalt electrode (36 ~ 40 mV/dec). The performance of the pretreated cobalt electrode as a potentiometric phosphate sensor was also investigated in terms of lifetime (7 weeks at room temperature), response rate (less 40 s), stability (n = 10, RSD 1.07 %) and acid-base adaptability (pH 4.0 ~ 8.0), and the sensor was successfully used for phosphate in oilfield re-injection water, lake water and tap water samples with satisfactory results.

An Electrochemical Sensor Based on Cu-MOF-199@MWCNTs Laden with CuNPs for the Sensitive Detection of Creatinine.

In this study, the synthesis of Cu-MOF-199@multiwalled carbon nanotubes (Cu-MOF-199@MWCNTs) composites was achieved and utilized to create an advanced electrochemical sensor for creatinine (Cre) detection. The composites were modified on a glassy carbon electrode surface through direct drip coating, followed by the deposition of copper nanoparticles (CuNPs) via constant potential deposition. Characterized by various techniques and electrochemical analyses, the Cu-MOF-199@MWCNTs composite increased the CuNPs load, improving the detection sensitivity for Cre. Under optimal conditions, the modified electrode exhibited good linearity across a broad range of Cre concentrations (0.05-40.0 μM) with a low detection limit of 11.3 nM. The developed sensor demonstrated remarkable stability, reproducibility, and selectivity, showing promise in sensitive and accurate Cre detection in serum samples.

Electrochemical immunosensor based on MOF for rapid detection of 6-benzyladenine in bean sprouts

6-benzylaminopurine (6-BA) is a widely used plant growth promoter. However, it can lead to precocious puberty and cause acute poisoning and even cancer of consumer. Thus, it is necessary to establish rapid and sensitive method for the detection of 6-BA. Electrochemical immunosensor is a new kind of biosensor, which combines the high selectivity of antibody with the high sensitivity of electrochemical sensor. In this study, an electrochemical immunosensor was developed for the detection of 6-BA in bean sprouts. The carbon material of Zn/Ni-ZIF-8–800 derived from bimetal-organic framework was synthesized by solvothermal method. Then, Zn/Ni-ZIF-8–800 was ultrasonically mixed with the highly conductive graphene, and the gold nanoparticles (AuNPs) were reduced by constant potential deposition (AuNPs/Zn/Ni-ZIF-8–800 @graphene). Finally, the antibody of 6-BA was combined with the prepared material to make an electrochemical immunosensor. The prepared materials were characterized by XRD, FTIR, SEM, TEM and XPS analyses. In addition, the electron transfer abilities of the modified sensors were investigated by CV and EIS. The established immunosensor presented a wide linear range (0.08–50 ng/mL), low detection limitation (0.24 ng/mL) and satisfactory recovery rates towards 6-BA (90.9–105.0 %). In brief, an electrochemical immunosensor with high sensitivity and selectivity was developed, which could be used to detect 6-BA in bean sprouts effectively.

Development of a Bifunctional Ti-Based Gas Diffusion Electrode for ORR and OER by One- and Two-Step Pt-Ir Electrodeposition.

The present paper presents one- and two-step approaches for electrochemical Pt and Ir deposition on a porous Ti-substrate to obtain a bifunctional oxygen electrode. Surface pre-treatment of the fiber-based Ti-substrate with oxalic acid provides an alternative to plasma treatment for partially stripping TiO2 from the electrode surface and roughening the topography. Electrochemical catalyst deposition performed directly onto the pretreated Ti-substrates bypasses unnecessary preparation and processing of catalyst support structures. A single Pt constant potential deposition (CPD), directly followed by pulsed electrodeposition (PED), created nanosized noble agglomerates. Subsequently, Ir was deposited via PED onto the Pt sub-structure to obtain a successively deposited PtIr catalyst layer. For the co-deposition of PtIr, a binary PtIr-alloy electrolyte was used applying PED. Micrographically, areal micro- and nano-scaled Pt sub-structure were observed, supplemented by homogenously distributed, nanosized Ir agglomerates for the successive PtIr deposition. In contrast, the PtIr co-deposition led to spherical, nanosized PtIr agglomerates. The electrochemical ORR and OER activity showed increased hydrogen desorption peaks for the Pt-deposited substrate, as well as broadening and flattening of the hydrogen desorption peaks for PtIr deposited substrates. The anodic kinetic parameters for the prepared electrodes were found to be higher than those of a polished Ir-disc.

Facile synthesize surfactants and binder-free nanoflake Co(OH)2 on CuCo2S4 nanowire for highly sensitive and selective non-enzymatic glucose sensor

The cross-linked Co(OH)2/CuCo2S4/Ni composite material has been successfully prepared by a simple method. CuCo2S4 nanoneedles are grown on NF by hydrothermal method, and then Co(OH)2 nanolayer was constructed by constant potential deposition. This nanostructure provides a good conductive network for effective charge transfer, which can detect direct and non-enzymatic reactions of glucose oxidation at low potential. In this paper, the microstructure and electrochemical properties of the prepared Co(OH)2/CuCo2S4 composites were characterized and tested. In the electrochemical sensing process, Co(OH)2/CuCo2S4 nanomaterials show high sensitivity, low detection limit, excellent selectivity, and linear response, reaching wide linear range of 1 μM-6.957 mM, high sensitivity of 2714.7 μA mM−1 cm−2 and a low detection limit of 0.26 μM. In addition, the sensor shows fast response time (within 2.5s), excellent selectivity and stability. CuCo2S4 nanowire array increases active surface area for the catalytic reaction and act as a stable conductive scaffold of Co(OH)2 to promote electron transfer. This low-cost and straightforward detection method offers a new strategy for non-enzymatic glucose detection.

Direct Electrochemical Extraction of Sm from SmCl3 in a Molecular Liquid Solvent Supported By LiNO3

Low-temperature electrochemical extraction of rare earth metals from their corresponding chlorides in ionic liquids has long been a scientific challenge. In this study, a new class of task-specific ionic liquids (ILs) containing Li elements, i.e. Li-containing solvate ionic liquids ([Li(DMI)n]3+NO3 —, 0.15 M LiNO3 dissolved in DMI (1,3-Dimethy-l-2-imidazolidinone)), is developed and used for metallic Sm electrodeposition from SmCl3. To elucidate the electrochemical deposition mechanism, the ionic component of the DMI/LiNO3 system was characterized by a range of instrumental analysis techniques (including 7Li NMR, UV-vis) and theoretical calculations. Cyclic voltammetry was used to explore the electrochemical behavior of Sm-containing species in the ionic liquid. Finally, metallic Sm was successfully obtained using constant potential deposition on high purity Al substrates which was confirmed by XPS and SEM. Li-containing solvate ILs have immense potential in green electrometallurgy because of their higher tunability and similar properties to ILs.

Co‐Electrodeposition of Nanostructured Ce‐NiOx on Stainless‐Steel Substrates for the Oxygen Evolution Reaction under Alkaline Conditions

AbstractThe development of cost‐effective catalysts that can be fabricated at scale for electrochemical water oxidation is an ongoing challenge. Here it is shown that stainless‐steel AISI316 is an appropriate support electrode for a co‐electrodeposited Ni‐CeOx catalyst for the oxygen evolution reaction (OER) under alkaline conditions. Optimal OER performance is achieved via a cyclic voltammetric deposition protocol rather than constant potential deposition for the catalyst layer. An overpotential of 300 mV at a current density of 10 mA cm−2 is recorded with a Tafel slope of 43 mV dec−1 while the catalyst also demonstrates long‐term stability. It is also found that the catalyst layer changes significantly after the OER. This includes changes to the catalyst morphology, distribution of oxidation state, and speciation as well as the transformation from an entirely amorphous material into one containing crystalline regions. This simple one‐step electrodeposition process on a cost‐effective substrate should, in principle, facilitate the fabrication of low‐cost electrolyzers.

High capacity polycarbazole-sulfur cathode for use in lithium-sulfur batteries

The potential use of electrochemically polymerized polycarbazole as an additive in lithium-sulfur battery cathodes has been investigated. Optimization of the polymer properties considered solvent, electrolyte and current-time profile during electropolymerization. It was found that electrodeposition from LiClO4-acetonitrile electrolyte and constant-potential deposition (at 1.15 V vs Ag/Ag+) gives the highest initial discharge capacity. This is most likely due to an optimum combination of specific surface area and conductivity.To improve the quality of the cathode, a slurry of carbon disulfide and dimethyl formamide was devised to balance the dispersion of carbon black and the solubility of sulfur. In 2032-coin cells, against a lithium anode, a polycarbazole-sulfur (PCBz-S) cathode with 30% sulphur showed the highest initial discharge capacity. A very good coulombic efficiency of around 98% and a capacity retention of over 91% for 50 charge/discharge cycles were obtained for the optimized PCBz-S cathode. Based on the cycling performance, PCBz is a potentially useful additive to mitigate the polysulfide shuttle effect. In addition, the electropolymerized carbazole matches the performance of a commercial polypyrrole that has been widely used as a conductive binder.

Preparation and magnetic properties of gradient diameter FeCoNi alloys nanowires arrays

FeCoNi MNWs with uniform and gradient diameter are successfully prepared by three-electrode constant potential deposition in AAO template. The deposition time of FeCoNi MNWs overgrow in the AAO template are investigated. The morphology and structure of FeCoNi MNWs are characterized by TEM, EDS, SAED and XRD. The effects of magnetization reversal mechanism, magnetic interaction, magnetic domain states and reversibility of FeCoNi MNWs are studied by FORCs technology. The results show that the magnetization reversal mechanism of UDNWs-20 present coherent mode, while UDNWs-60 and UDNWs-100 present curling mode as well as coherent mode. There is a transition of curling inverse to coherent inverse in magnetic reversal of GDNWs-20~100. When the UDNWs diameter increase from 20 nm to 60 nm and 100 nm, the domain state change from SD to MD state and the irreversible component reduce from about 100% to 71.3% and 60.2%. The SD GDNWs-20~100 contains 72.8% irreversible and 27.2% reversible components. The magnetic interaction, magnetic domain states and reversibility of FeCoNi GDNWs are different from those of UDNWs.

Recovery of Pd(II) from Hydrochloric Acid Medium by Solvent Extraction-Direct Electrodeposition Using Hydrophilic/Hydrophobic ILs.

Mixed [C8bet]Br/[C4mim][NTf2] ionic liquids were used as a new extraction system to extract Pd(II) from multimetal-ion solutions. The separation factors KPd/M (M: Cu, Fe, Ni, Zn, Co) are greater than 103. Thiourea was found to be an effective stripping agent. After three cycles, the recovery efficiency was higher than 91.0%. Direct electrodeposition of palladium from the mixed ionic liquid phase was also studied. The Pd(II) complex in [C8bet]Br/[C4mim][NTf2] system was studied by cyclic voltammetry at 348 K. The results indicate the existence of three types of Pd(II) complex in the [C8bet]Br/[C4mim][NTf2] system, leading to three reductive waves. The reduction of Pd(II) to Pd(0) in this system is irreversible. A uniform black coating was obtained by constant-potential deposition at −1.7 V on a nickel foil, confirmed to be palladium metal by energy-dispersive spectrometry, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy analyses. After three cycles of continuous extraction–electrodeposition, over 90.0% of palladium was recovered.

Controlling the surface morphologies, structural and magnetic properties of electrochemically fabricated Ni–Co thin film samples via seed layer deposition

In this study, the influence of the seed layer deposition on the surface morphologies, structural and magnetic features of the thin film samples of Ni–Co was investigated and results are reported. The samples were produced on indium tin oxide (ITO)-coated glass substrates with and without a seed layer by electrochemical deposition technique under a constant deposition potential. To explore the effect of the seed layer current density (SLCD) on thin films, prior to actual deposition, Ni–Co seed layers were introduced on the ITO substrates at varying current densities. The EDX analysis indicated that the samples exhibited identical deposit compositions and an anomalous co-deposition behavior regardless of the SLCD. The Ni–Co samples fabricated under this study had a face centered cubic (fcc) phase structure with preferred crystallographic orientation being in the [111] direction perpendicular to the sample plane. Furthermore, the crystallite size, crystallinity, particle size and surface roughness of the samples showed a strong dependency on applied SLCD. All Ni–Co samples, irrespective of the SLCD, featured stripe magnetic domain structure and in-plane magnetic hysteresis loop with an out-of-plane magnetization component. It was also observed that while a semi-hard magnetic characteristic was detected in all samples, the coercive field varied with the SLCD.

Electrodepositing DNA Self-Assembled Monolayers on Au: Detailing the Influence of Electrical Potential Perturbation and Surface Crystallography.

The preparation of DNA self-assembled monolayers (SAMs) on single-crystal gold bead electrodes using an applied potential is evaluated with in situ electrochemical fluorescence microscopy. Applying a constant deposition potential or a square-wave potential perturbation during the formation of DNA SAMs is compared for two different modification methods: DNA SAM formation on a clean gold surface followed by alkythiol backfilling (as is typically done in the literature) or via thiol-exchange on an alkylthiol-modified gold surface. DNA SAMs prepared from a chloride-containing deposition buffer were not significantly different when using either square-wave potential perturbation or at a constant applied potential even when considering different surface crystallographies. Greater variations were observed when applying more positive potentials for both DNA thiol-exchange and DNA adsorption on clean Au. Our results suggest that using either a constant potential or a square-wave potential perturbation for 5 min both create defects by weakening the gold-thiol interaction. When the deposition is performed with the adsorption of chloride ions from the electrolyte, the electrodeposition results in a similar increase in DNA coverage when compared to depositions performed at open circuit potentials.

Effect of the Composition of Co-W Oxide Conversion Layer on the Cr-Diffusion Barrier Property for SOFC Interconnect

Introduction. Solid-oxide fuel cells (SOFC) seems to the most reasonable solution for the next power generation because of high efficiency, low CO2 emission, and fuel flexibility. In the operation condition of SOFC, however, Cr in the stainless steel will react with O2 and H2O in the atmosphere to form CrO2(OH)2 or CrO3 gas which cause detrimental effects on cathode materials. Formation of Cr2O3 will also lead to high electrical resistance which decreases the cells efficiency. We found that a CoWO4 layer formed by the oxidation of Co-2.4 at% W electroplated stainless steel immediately in oxidation at 800 ˚C. This layer blocks the outward diffusion of Cr ion for it does not accommodate Cr3+ ion. As a result, no Cr was found at the oxide surface, and the thickness of inner Cr2O3 layer kept thin. However, we utilized only Co-2.4 at% W plating in the previous work, and the effect of plating composition was known. In this study, Co-W electrodeposition to obtain a wide range of W content was examined, then the high-temperature oxidation and area specific resistance (ASR) of the oxidized specimen was tested. Experimental. Type 430 (Fe-17 mass% Cr) and 445 (Fe-23 mass% Cr-1 mass% Mo) stainless steels were used as a substrate. The cathodic current density was 1-5 A dm-2 and plating time was adjusted to obtain a 10 µm of electroplating. Electroplating of Co-W alloy was carried out with sodium tungstate and citric acid solution at pH range of 2-10. Cathodic polarization and constant potential deposition were carried out with a Cu working electrode (cathode), Pt counter electrode (anode) and an Ag-AgCl reference electrode immersed in a saturated KCl solution. A thin Co layer was electroplated to enhance the adherence before Co-W electroplating at constant current density. After the electroplating at constant current densities, the samples were oxidized at 800 ºC in the air with 3 vol% water vapor with the flow rate of 100 cm3 min-1. X-ray diffraction (XRD) was used to identify crystal phase before and after the oxidation test. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS) were used to observe and analyze morphology and distribution of the element to the depth direction of the oxide. ASR was measured at 800 ˚C for 100 h in air at the constant current of 0.5 A dm-2. Samples were pressurized at 30 kPa during the measurement. Results. (1) A uniformly distributed Co-W electroplating film with 2.4-30 at% W was deposited on Type 430 and 445 stainless steel. The alloy composition was determined only by the solution pH. Cathodic current density did not affect to the composition. (2) Co-W alloy plating with less than 5 at% W is enough to obtain Cr barrier layer. For the specimen with W content higher than 5 at% formed an W enriched layer within the substrate layer. Whether the formation of this layer is detrimental to oxidation and mechanical properties is not known, the thickness and the compactness of formed CoWO4 layer after oxidation are similar for the electroplating containing >5 at% W. (3) Both the increasing W content in deposits and decreasing Fe fraction in the substrate will lead to the reduction of Fe outward diffusion. Also, the increasing in W content lead to higher ASR.

Wireless electrochemical preparation of gradient nanoclusters consisting of copper(II), stearic acid and montmorillonite on a copper wire for headspace in-tube microextraction of chlorobenzenes.

This work introduces a new gradient fiber coating for microextraction of chlorobenzenes. Nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by wireless electrofunctionalization. The resultant gradient coatings are more robust, and thermally and mechanically stable. Wireless electrofunctionalization was carried out in a bipolar cell under a constant deposition potential and using an ethanolic electrolyte solution containing stearic acid and montmorillonite. Stearic acid acts as an inexpensive and green coating while montmorillonite acts as a modifier to impart thermal stability. The gradient morphology of the nanoclusters was investigated by scanning electron microscopy, thermogravimetric analysis and energy dispersive X-ray spectroscopy. The coated wire was placed in a hollow needle and used for headspace in-tube microextraction (HS-ITME) of chlorobenzenes (CBs). Effects of various parameters affecting synthesis and extraction were optimized. Following extraction, the needles were directly inserted into the GC injector, and the CBs (chlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene) were quantified by GC-MS. The limits of detection under optimized conditions range from 0.5 to 10ng.L-1. The intra- and inter-day relative standard deviations (RSDs) (for n = 10, 5 respectively) using a single fiber are 6-10 and 10-15%, respectively. The fiber-to-fiber RSDs (for n = 3) is between 17 and 24%. The method was successfully applied to the extraction of CBs from real water samples, and relative recoveries are between 91 and 110%. Graphical abstract A gradient coating of organoclay-Cu nanoclusters was fabricated on a copper wire by wireless electrofunctionalization. The oxidation of copper takes place at the anodic pole (red) while dissolved oxygen in ethanol solution is reduced at the cathodic pole (blue).

Defective and “c-Disordered” Hortensia-like Layered MnOx as an Efficient Electrocatalyst for Water Oxidation at Neutral pH

The development of a highly active manganese-based water oxidation catalyst in the design of an ideal artificial photosynthetic device operating under neutral pH conditions remains a great challenge, due to the instability of pivotal Mn3+ intermediates. We report here defective and “c-disordered” layered manganese oxides (MnOx-300) formed on a fluorine-doped tin oxide electrode by constant anodic potential deposition and subsequent annealing, with a catalytic onset (0.25 mA/cm2) at an overpotential (η) of 280 mV and a benchmark catalytic current density of 1.0 mA/cm2 at an overpotential (η) of 330 mV under neutral pH (1 M potassium phosphate). Steady current density above 8.2 mA/cm2 was obtained during the electrolysis at 1.4 V versus the normal hydrogen electrode for 20 h. Insightful studies showed that the main contributing factors for the observed high activity of MnOx-300 are (i) a defective and randomly stacked layered structure, (ii) an increased degree of Jahn–Teller distorted Mn3+ in the MnO6 octa...

Electrodeposition of Aluminum onto Copper-Coated Printed Circuit Boards

The electrodeposition of aluminum thin films onto copper-coated printed circuit boards from aluminum chloride-trimethylphenylammonium chloride ionic liquids is studied. Various electrodeposition methods with different surface pretreatment procedures were investigated and compared to optimize the deposited aluminum morphology and properties. For the same amount of charge, a pulse current deposition approach applied at a low duty cycle of 10% allowed the use of higher deposition current densities, leading to finer and more compact aluminum deposits compared with those produced by constant potential and constant current deposition techniques. Pulse current deposition with various peak current densities of −25 mA/cm2 to −65 mA/cm2 was conducted over a temperature range of 20°C to 60°C. At a moderate temperature of 40°C, the electrodeposited aluminum layer was the most adherent. An increase of peak current density did not have an obvious effect on the deposit morphology, but it led to an increased amount of both deposited aluminum and incorporated impurities (oxygen and chloride). At room temperature, the electrical resistivity of the copper-coated printed circuit boards with deposited aluminum decreased as the peak current density for aluminum deposition increased.

Label-free and high-throughput biosensing of multiple tumor markers on a single light-addressable photoelectrochemical sensor

The sensitive and label-free detection of multiple biomarkers on a single electrode by photoelectrochemical (PEC) sensors based on light addressing strategies is very attractive for developing portable and high-throughput biosensing systems. The essential prerequisite of this proposal is the employment of uniform photovoltaic material modified electrodes with high conversion efficiency. Herein, a novel two-step constant potential deposition method for the rapid fabrication of bismuth sulfide film modified ITO electrodes (Bi2S3/ITO) was established. The produced Bi2S3/ITO, with excellent uniformity and high conversion efficiency in visible light ranges, was further modified with gold nanoparticles (AuNPs) and then divided into separated identical sensing zones by insulative paints. The adsorption-based immobilization of antibodies of three tumor markers, i.e., a-fetoprotein (AFP), carcinoembryonic antigen (CEA) and cancer antigen 19-9 (CA19-9), onto different sensing zones of the electrode and the further blocking with BSA established a label-free and light-addressable PEC sensor (LF-LAPECS), which can achieve the rapid and sensitive detection of these biomarkers with wide linear ranges, low detection limits and self-calibration ability. Moreover, the detection throughput can be conveniently improved by enlarging the size of the substrate electrode and increasing the number of separated sensing zones. The present work thus demonstrates the promising applications of PEC techniques for developing sensitive, time-saving, cost-effective and high-throughput biosensing methods.

Pd Nanoparticle Formation during Constant Potential Electrodepositions in Ionic Liquids

Electrodepositions in ionic liquids (ILs) allow for opportunities to improve deposited morphologies, access redox potentials that cannot be achieved in aqueous baths, and utilize less hazardous bath compositions. The driver to utilize ILs for Pd electrodeposition is to minimize hydrogen embrittlement challenges commonly associated with Pd electrodeposition in aqueous electrolytes. Generally, the resulting Pd deposits in ILs are thin films, loosely adhered fine powders or dendritic structures, depending upon the IL selected and the electrochemical parameters used(1, 2). Recently, it has also been shown that electroreduction of Pd in ILs can result in nanoparticles being formed in solution, rather than on an substrate electrode when high overpotentials are used(3). Previously, we showed Pd nanosphere formation can be controlled through potentiostatic pulse deposition in 1-butyl, 3-methylimidazolium chloride [Bmim][Cl] onto Ni electrode substrates(4). The nanosphere size was found to be a function of cycle time. In contrast, using 1-buty, 1-methylpyrrolidinum dicyanamide [Bmpyrr][DCA] under constant potential conditions, thin film Pd layers on nickel electrode substrates were obtained(5). We will present how, upon further investigation, these Pd “thin films” formed from constant potential deposition in [Bmpyrr][DCA] are actually agglomerates of nanoparticles that can be scraped off the Ni substrate and dispersed in solution in an unagglomerated state. These nanoparticles have an average size of 6.3 ± 1.6 nm when deposited at -2.3V vs. Fc/Fc+. Further investigation into the conditions for electrodeposition in ILs where it was thought that thin films were formed will also be discussed to better understand if the resulting deposits were truly thin films and not nanoparticle agglomerations.

(Invited) Systematic Engineering of Structured Magnetic Nanowire Arrays for Three-Dimensional Data Storage

A preparative strategy is presented towards a three-dimensional magnetic data storage medium based on arrays of parallel, cylindrical metallic nanowires structured along their length. The preparation utilizes porous anodic alumina as an inert template that defines the geometry (cylinder length, diameter and pitch), combined with galvanic deposition of the functional materials inside the pores. We demonstrate that the composition of nickel-cobalt alloys can be tuned systematically at one constant deposition potential, whereby the magnetocrystalline anisotropy can be minimized. The wires then display maximal shape anisotropy. The definition of bits along the 'vertical' direction of each wire is performed either by the introduction of non-magnetic segments or by modulation of the pore diameter. The former strategy is made possible by pulsed electrodeposition from a ternary electrolyte. The latter structure is achieved by combining several anodization steps. We demonstrate the presence of magnetic domain boundaries at such designed pinning points using bulk magnetometry and single-wire imaging techniques. As future read/write elements we embed ultrathin oxide layers at mid-height of the wires by atomic layer deposition, and we demonstrate a measurable magnetoresistance effect of these layers. Figure 1