Electrodeposition Charge Research Articles

Electrodeposition of Fractal Structured Nickel for Hydrogen Evolution Reaction in Alkaline

AbstractTo accelerate the practical application of water splitting in alkaline media, it is imperative to enhance the electrocatalytic performance for the Hydrogen Evolution Reaction (HER). In this context, we demonstrate that a simple (one‐pot, one‐step) electrodeposition process of nickel (Ni) in the presence of 3,5‐diamino1,2,4‐triazole (DAT) results in the formation of fractally structured Ni films with a significantly increased surface area. The Electrochemically active surface area (ECSA) increases with the electrodeposition charge passed, with the film electrodeposited at 14 C cm−2 achieving a reduction in overpotential at −10 mA cm−2 (η10) to 65.7 mV, coupled with a remarkable increase in ECSA (114‐fold greater than that of Ni‐foil). Additionally, nickel deposited in the presence of DAT effectively mitigates deactivation during electrolysis, exhibiting a 3.6‐fold lower overpotential degradation compared to that of the smooth Ni foil. This simple electrodeposition technique, applicable to a variety of conductive substrates, is distinguished by its high catalytic performance in the HER, a feature of considerable significance.

Platinum and palladium nanoparticles on boron-doped diamond for the electrochemical detection of hydrogen peroxide: a comparison study.

Hydrogen peroxide (H2O2) plays a role in many facets - a household item, an important industrial chemical, a biomarker in vivo, and several others. For this reason, its measurement and quantification in a variety of media are important. While spectroscopic detection is primarily used for H2O2, electrochemical methods offer advantages in versatility, cost, and sensitivity. In this work, we investigate a 2-step surface metal nanoparticle (NP) modification for platinum (Pt) and palladium (Pd) on boron-doped diamond (BDD) electrodes for the detection of H2O2. Several parameters such as the metal salt concentration and electrodeposition charge in the 2-step modification were varied to find an optimum. Using cyclic voltammetry (CV), the BDD-PdNP electrode types were found to yield a sharper, more well-resolved H2O2 oxidation peak compared to the BDD-PtNP electrodes. Both metal NP electrode types significantly improved the response compared to the bare BDD electrode; a 150-200× improvement in sensitivity was observed across all modified electrode types. Calibration experiments were completed at both low and high concentration ranges in stagnant and flow-based solutions. The lowest limit of detection (LOD) obtained was 50 nM (5E-08 M) on a BDD-PdNP electrode modified with 1.0 mM PdCl2 to 5.0 mC in the wet chemical seeding and electrodeposition steps. 0.25 mM PdCl2 to 3.23 mC and 0.25 mM HPtCl6- to 3.23 mC also yielded a sufficient response for low-level H2O2, with LODs around 100 nM (1E-07 M). Overall, this work exemplifies the wide applicability of BDD and achieves sub-μM H2O2 LODs with a non-enzymatic electrode material.

Properties of Electro-Deposited CuSCN Thin Films with Different Electrodeposition Charge Density

The development of efficient CuSCN hole transport layers is crucially important for achieving high photovoltaic performance in inorganic perovskite devices. In this study, the effects of electrodeposition charge density on the morphological/microstructural and electrical properties and the formation mechanism of electro-deposited CuSCN films are investigated and discussed. The results indicate that the charge density is the key factor that governs not only the thickness, but also morphological, electrical, and surface properties of the electro-deposited CuSCN films. For the energy band diagram property, we found that when the charge density is 120 mC cm−2 (named as CD120), the valance band of CuSCN near ITO work function. This excellent property can efficiently improve the photovoltaic performance of inorganic perovskite devices, where ITO and CuSCN are employed, owing to the reduction of energy barrier. Among the films electro-deposited at different charge densities, the CD120 exhibits the highest mobility, possibly due to the excess amount of SCN in the thin film.

TiO2 nanotubes modified with cobalt oxyphosphide spheres for efficient electrocatalytic hydrogen evolution reaction in alkaline medium

Electronic and surface modulation through coupling between oxygen and phosphorous in cobalt oxyphosphide (CoOP) is identified as an effective approach to enhancing the electrocatalytic hydrogen evolution reaction (HER) in an alkaline medium. This work demonstrates a one-step and safe electrodeposition method to modify the surface of ordered titania nanotubes (TNTs) with CoOP spheres. The effect of electrodeposition charge density, pH of the electrodeposition bath, and presence of citric acid on the electrocatalytic HER performance of CoOP-modified TNTs was investigated. The Ti/TNTs/CoOP electrode requires only 130 mV overpotential to deliver 10 mA cm−2 in a 1.0 M KOH electrolyte. The Tafel slope is estimated to be 72.5 mV dec−1. Both the HER performance and Tafel value of Ti/TNTs/CoOP are superior to CoOP deposited on bare Ti foil (165 mV and 78.4 mV dec−1), FTO (185 mV; 88.1 mV dec−1), and glassy carbon (214 mV; 93 mV dec−1). The electrochemically active surface area (ECSA) and impedance spectroscopy findings revealed that the synergistic coupling between the CoOP and TNTs enhances the surface area and density of accessible active sites while reducing the charge transfer resistance at the electrode/electrolyte interface. Such a synergistic effect is ascribed to the effective electronic interaction between CoOP and TNTs, and the faster electron transfer kinetics because of the unidirectionality of the 1-D TNTs.

Photoelectrodeposition of Pt nanoparticles on Sb2Se3 photocathodes for enhanced water splitting

One of the biggest challenges around photochemical materials is to develop highly active and stable catalysts, if possible, with a simple synthesis methodology. This study presents the photoactivity of Sb2Se3 semiconductor containing Pt nanoparticles obtained with a fast deposition rate. The deposition of Pt nanoparticles using the electrodeposition (ED) and photoelectrodeposition (PED) methods was investigated. Even with the same electrodeposition charge, the photocatalyst prepared using PED resulted in a material with photocurrent density almost three times higher than the one prepared through ED. There is a difference in the nucleation and growth kinetics of Pt nanoparticles between the two methods. The Pt growth using ED was characterized by the agglomeration of Pt with consequent formation of larger metal particles, while PED generated new sites for the metal deposition, allowing a better distribution of Pt on the surface of the semiconductor and improving the photocurrent density, charge transfer, and photoconversion of the photocatalyst.

Microstructural characterization of Cu-Sn-Zn electrodeposits produced potentiostatically from acid baths based on trisodium nitrilotriacetic

This study characterizes the Cu-Sn-Zn electrodeposits produced potentiostatically from baths containing different concentrations of Cu2+, Sn2+ and Zn2+ ions and 0.60 M trisodium nitrilotriacetic (NTA) at pH 4.99 (higher stability). Ternary electrodeposits were produced onto AISI 1010 steel substrate at electrodeposition potential of −1.60 V with electrodeposition charge density of 3.0 Ccm−2. Chemical composition of electrodeposits varied significantly, presenting higher Cu content (at.%) than that of other elements. Furthermore, it was verified that the high concentration of Sn2+ ions in the baths hindered the reduction of Zn2+ ions, leading to Zn-poor electrodeposits. Microstructure was generally composed of irregular crystallites and clusters of crystallites or dendrites dispersed on the surface, depending on chemical composition. X-ray diffraction showed formation of the ternary alloy by mixture of the Cu5Zn8, η-Cu6Sn5 and Sn pure phases. In addition, electrodeposits with lower Cu content (at.%) also showed the SnO phase. Surface topography of the electrodeposits presented a rough aspect, with arithmetic roughness varying from 1.83 to 3.90 μm for electrodeposits with lower and higher Sn content (at.%), respectively. Adhesion tests indicated that the highest and lowest adherence percentages to the steel substrate were observed for the electrodeposits with the largest Zn and Sn contents (at.%), respectively.

Electrochemical deposition and characterization of AgPd alloy layers

The AgPd alloys were electrodeposited onto Au and glassy carbon disc electrodes from the solution containing 0.001 mol dm-3 PdCl2 + 0.04 mol dm-3 AgCl + 0.1 mol dm-3 HCl + 12 mol dm-3 LiCl under the non-stationary diffusion (quiescent electrolyte) and convective diffusion (? = 1000 rpm) to the different amounts of charge and at different current densities. Electrodeposited alloy layers were characterized by the anodic linear sweep voltammetry (ALSV), scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The compositions of the AgPd alloys determined by the EDS were almost identical to the theoretically predicted ones, while the compositions obtained by XPS and ALSV analysis were similar to each other, but different from those obtained by EDS. Deviation from the theoretically predicted values (determined by the ratio jL(Pd)/j(Ag)) was more pronounced at lower current densities and lower charges of AgPd alloys electrodeposition, due to the lower current efficiencies for alloys electrodeposition. The ALSV analysis indicated the presence of Ag and Pd, expressed by two ALSV peaks, and in some cases the presence of the additional peak, which was found to correspond to the dissolution of large AgPd crystals, formed at thicker electrodeposits (higher electrodeposition charge), indicating, for the first time, that besides the phase structure, the morphology of alloy electrodeposit could also influence the shape of the ALSV response. In addition to Ag and Pd, the XPS analysis confirmed the presence of AgCl at the surface of samples electrodeposited to low thicknesses (amounts of charge).

ZnO/CdS nanorod arrays decorated by layered double hydroxides for efficient solar water oxidation

Developing efficient photoanode without either hole scavenger or noble-metal co-catalyst is extremely important for solar water oxidation. However, in most cases, hole scavengers such as Na2S and/or Na2SO3 are usually used to inhibit carrier recombination while blocking the real water oxidation process. To avoid this, non-noble metal co-catalyst, that is, CoNi layered double hydroxides (LDHs), has been successfully deposited onto ZnO/CdS core-shell nanorod arrays for efficient photoelectrochemical water oxidation in KOH aqueous solution. By changing the deposition cycle numbers from 10 to 25 for CdS and tuning the electrodeposition charge quantities from 0.1 to 0.4 C for CoNi LDHs layers, the effect of thickness or loading of CdS and CoNi LDHs on light absorption and photocurrent was systematically studied. A transformation from M(OH)2 to MOOH (M═Co, Ni) is found when the photoexcited holes in CdS are transferred to CoNi LDHs, making the co-catalyst more active than before. These high active M3+ sites, combined with the high absorption over visible light, fast-charge transfer along the 1D ZnO tunnels, and low-charge transfer resistance at photoanode/electrolyte interfaces, endow the ZnO/CdS/CoNi LDHs nanoarrays photoanode with a photocurrent of 2.87 mA/cm2 at 1.0 VRHE and incident photon-to-current efficiency of 36% at 450 nm. The work provides an effective strategy toward efficient solar water oxidation free of hole scavengers. Copyright © 2017 John Wiley & Sons, Ltd.

A feasible electrochemical method for tuning coatings wettability from superhydrophilicity to superhydrophobicity

A feasible electrochemical method for controlling arbitrarily the surface wettability between superhydrophilicity and superhydrophobicity was presented in details. A series of composited polythiophene films (PL-PEDOT) with wettability from superhydrophilicity to superhydrophobicity were readily fabricated by tuning precisely the electrodeposition charge (EC) of overlying hydrophobic poly(2,2′-bithiophene) (PLTH) moieties on the underlying poly(3,4-ethylenedioxythiophene) (PEDOT) moieties. The various wettability of the resulting PL-PEDOT film could be attributed to the combination of the conducting and porous nanostructure of PEDOT films and the flexible electrodeposition strategy. The wettability change of PL-PEDOT films is also companied by the changes in their spectral colors. This electrochemical method could present a feasible technique for the preparation of various wettability surfaces in practical applications.

Electrodeposition and characterization of binary Fe-Mo alloys from trisodium nitrilotriacetate bath

An alkaline solution for the electrodeposition of Fe-Mo alloys was developed with trisodium nitrilotriacetate (NTA3−) as the complexing agent for Fe(III). The Fe-Mo voltammetric profile in the presence of 0.11M NTA and 0.055M NTA showed, respectively, two cathodic waves and one cathodic wave. Analysis of chemical composition by EDS of electrodeposits produced voltammetrically up to several final electrodeposition potentials (Ef) showed that they contained Fe, Mo and O, depending on Ef. SEM of Fe-Mo electrodeposits with electrodeposition charge density (qd) 95.55Ccm−2, produced potentiostatically with 0.055M and 0.11M NTA, showed uniform films formed by coalesced globular crystallites, depending on the deposition potential (Ed). EDS analysis of Fe-Mo electrodeposits produced with qd 95.55Ccm−2 in the presence of 0.11M NTA showed that the Mo content varied with Ed from 23.3wt% to 66.2wt%, whereas in the presence of 0.055M NTA it varied with Ed from 58.6wt% Mo to 64.4wt%. XRD analysis of the Fe-Mo electrodeposits produced with qd 95.55Ccm−2, regardless of the NTA concentration, indicated that the Fe-Mo electrodeposits could be of low crystallinity or partially amorphous.

Study of the influence of the trisodium nitrilotriacetic as a complexing agent on the copper, tin and zinc co-deposition, morphology, chemical composition and structure of electrodeposits

The electrodeposition of Cu–Sn–Zn ternary alloys on to AISI 1010 steel from an acid bath, pH4.99, containing trisodium nitrilotriacetic (NTA) was investigated, with different proportions of the metal ions in the baths. The Cu–Sn–Zn voltammetric profile showed four cathodic regions, irrespective of bath composition. The first three regions were associated with the reduction of the Cu-NTA and Sn-NTA complexes, and in the last region with Cu-NTA, Sn-NTA and Zn-NTA complexes reduction, attributed through of the analysis of the voltammetric curves together with the energy-dispersive X-ray spectroscopy (EDS) results. EDS analysis showed that only in cathodic region c4 occurred the transition from Cu–Sn binary alloy to Cu–Sn–Zn ternary alloy, regardless of bath composition. In addition, Cu–Sn–Zn co-deposition, at Ed−1.60V (cathodic region c4), was normal regardless of bath composition. Analysis of the photomicrographs of Cu–Sn–Zn electrodeposits obtained at electrodeposition potential (Ed) –1.60V, with electrodeposition charge density (qd) of 3.0Ccm−2, from 0.20Cu2+/0.050Sn2+/0.050Zn2+ bath presented the highest grain size (0.77μm) and from 0.15Cu2+/0.075Sn2+/0.075Zn2+ bath presented smaller grain size (0.27μm), all formed by irregular crystallites. Adhesion test showed that the Cu–Sn–Zn electrodeposit obtained at Ed−1.60V, with qd 3.0Ccm−2, from 0.10Cu2+/0.10Sn2+/0.10Zn2+ bath presented a good adherence to the 1010 steel substrate, being classified as Gr2. Laser scanning confocal microscopy (LSCM) showed that roughness increased from 1.48μm to 2.98μm when Cu2+ ions concentration in the electrodeposition baths decreased. X-ray diffraction pattern indicated that the Cu–Sn–Zn electrodeposits produced at Ed−1.60V with qd 3.0Ccm−2, depending on bath composition, presented structure crystalline with a mixture of Sn, SnO, CuZn, Cu5Zn8, η-Cu6Sn5 and Cu20Sn6 phases, indicating the formation of Cu–Sn–Zn ternary alloy.

The biological and electrical trade-offs related to the thickness of conducting polymers for neural applications

Poly(3,4-ethylenedioxythiophene) (PEDOT) films have attracted substantial interest as coatings for platinum neuroprosthetic electrodes due to their excellent chemical stability and electrical properties. This study systematically examined PEDOT coatings formed with different amounts of charge and dopant ions, and investigated the combination of surface characteristics that were optimal for neural cell interactions. PEDOT samples were fabricated by varying the electrodeposition charge from 0.05 to 1Ccm−2. Samples were doped with either poly(styrenesulfonate), tosylate (pTS) or perchlorate. Scanning electron micrographs revealed that both thickness and nodularity increased as the charge used to produce the sample was increased, and larger dopants produced smoother films across all thicknesses. X-ray photoelectron spectroscopy confirmed that the amount of charge directly corresponded to the thickness and amount of dopant in the samples. Additionally, with increased thickness and nodularity, the electrochemical properties of all PEDOT coatings improved. However, neural cell adhesion and outgrowth assays revealed that there is a direct biological tradeoff related to the thickness and nodularity. Cell attachment, growth and differentiation was poorer on the thicker, rougher samples, but thin, less nodular PEDOT films exhibited significant improvements over bare platinum. PEDOT/pTS fabricated with a charge density of <0.1Ccm−2 provided superior electrochemical and biological properties over conventional platinum electrodes and would be the most suitable conducting polymer for neural interface applications.

Zinc electrodeposition from alkaline solution containing trisodium nitrilotriacetic added

Abstract An alkaline solution for the electrodeposition of Zn was developed, with trisodium nitrilotriacetic (NTA) as the complexing agent for Zn(II). The voltammetric studies showed that the NTA has a beneficial effect, displacing the initial reduction potential of Zn(II) species to more positive values than in its absence. Cyclic voltammetry of 1010 steel in alkaline Zn electrodeposition solution with 0.20 M NTA indicated the occurrence of the Zn underpotential electrodeposition, UPD, (regions wave c ′ and c ″) and followed by Zn overpotential electrodeposition, OPD (region peak c ‴). The Zn electrodeposit produced voltammetrically at limiting potential ( E f ) −0.81 V (region wave c ′) was characterized by XRF and showed Zn presence. Zn electrodeposits produced potentiostatically at a potential −1.26 V were characterized by means of SEM, EDS and XRD. SEM results showed that fine-grain and compact Zn electrodeposits were obtained in the presence of 0.20 M NTA, at an electrodeposition charge density ( q d ) of 10.0 C cm −2 . AFM analysis showed that the roughness of the Zn electrodeposits is greater in the presence than absence of 0.20 M NTA to both q d 2.0 and 10.0 C cm −2 . The adhesion test showed that the Zn electrodeposits, in general, had no area detached. The XRD pattern revealed that the Zn electrodeposits had a crystal structure with preferential orientation [0 0 2]. It was showed that NTA was a suitable complexing agent for the electrodeposition of Zn without dendrites and cracks.

A Comparative Study of the Electrodeposition of Nanoporous Ir and Pt Thin Films

This work compares the properties of thin, porous Ir and Pt films, formed by electrodeposition (ED) from solutions containing their respective chloro-complexes, in preparation for the future co-electrodeposition of thin Pt-Ir alloy films for electrocatalytic applications. ED was carried out on Au using potentiodynamic and potentiostatic methods with simultaneous in situ mass measurements, using the quartz crystal microbalance technique. While Ir ED is found to depend on the ED potential in a more complex manner than does Pt, the specific surface area (SSA) of both metal films increases linearly with potential, but decreases with increasing solution concentration. All of the films were found to be highly porous, as confirmed using field emission scanning electron microscopy. The optimum conditions for Ir ED (0.2 V vs. RHE and a precursor concentration of < 0.05 mM) were found to be very suitable for Pt ED as well, giving films 1 to 5 nm in thickness, 25% in porosity, and exhibiting an ED charge efficiency of 75–95%.

Virus-poly(3,4-ethylenedioxythiophene) biocomposite films.

Virus-poly(3,4-ethylenedioxythiophene) (virus-PEDOT) biocomposite films are prepared by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) in aqueous electrolytes containing 12 mM LiClO(4) and the bacteriophage M13. The concentration of virus in these solutions, [virus](soln), is varied from 3 to 15 nM. A quartz crystal microbalance is used to directly measure the total mass of the biocomposite film during its electrodeposition. In combination with a measurement of the electrodeposition charge, the mass of the virus incorporated into the film is calculated. These data show that the concentration of the M13 within the electropolymerized film, [virus](film), increases linearly with [virus](soln). The incorporation of virus particles into the PEDOT film from solution is efficient, resulting in a concentration ratio of [virus](film):[virus](soln) ≈ 450. Virus incorporation into the PEDOT causes roughening of the film topography that is observed using scanning electron microscopy and atomic force microscopy (AFM). The electrical conductivity of the virus-PEDOT film, measured perpendicular to the plane of the film using conductive tip AFM, decreases linearly with virus loading, from 270 μS/cm for pure PEDOT films to 50 μS/cm for films containing 100 μM virus. The presence on the virus surface of displayed affinity peptides did not significantly influence the efficiency of incorporation into virus-PEDOT biocomposite films.

Electrodeposition of CdSe coatings on ZnO nanowire arrays for extremely thin absorber solar cells

We report on electrodeposition of CdSe coatings onto ZnO nanowire arrays and determine the effect of processing conditions on material properties such as morphology and microstructure. CdSe-coated ZnO nanowire arrays have potential use in extremely thin absorber (ETA) solar cells, where CdSe absorbs visible light and injects photoexcited electrons into the ZnO nanowires. We show that room-temperature electrodeposition enables growth of CdSe coatings that are highly crystalline, uniform, and conformal with precise control over thickness and microstructure. X-ray diffraction and transmission electron microscopy show nanocrystalline CdSe in both hexagonal and cubic phases with grain size ∼5 nm. Coating morphology depends on electrodeposition current density. Uniform and conformal coatings were achieved using moderate current densities of ∼2 mA cm −2 for nanowires with roughness factor of ∼10, while lower current densities resulted in sparse nucleation and growth of larger, isolated islands. Electrodeposition charge density controls the thickness of the CdSe coating, which was exploited to investigate the evolution of the morphology at early stages of nucleation and growth. UV–vis transmission spectroscopy and photoelectrochemical solar cell measurements demonstrate that CdSe effectively sensitizes ZnO nanowires to visible light.

Palladium Nanoparticles Decorated Single-Walled Carbon Nanotube Hydrogen Sensor

We developed a simple and cost-effective fabrication technique to construct a hydrogen nanosensor by decorating single-walled carbon nanotubes with Pd nanoparticles. By varying the sensor's synthesis conditions (e.g., Pd electrodeposition charge, deposition potential, and initial baseline resistance of the SWNT network), the sensing performance was optimized. The optimized sensor showed excellent sensing properties toward hydrogen (ΔR/R of 0.42%/ppm) with a lower detection limit of 100 ppm and a linear response up to 1000 ppm. The response time decreased from tens of minutes to a few minutes with increasing hydrogen concentration at room temperature. The sensor's recovery time improved under humid air conditions compared to dry air conditions.

Electrochemical properties of the polypyrrole films doped with benzenesulfonate

The electrochemical redox behavior of the polypyrrole films doped with benzenesulfonate was investigated by cyclic voltammetry, the surface morphology of the films was characterized by AFM, and the interactions between pyrrole oligomers and the benzenesulfonate anion were modeled with quantum chemical methods. It is the first systematic study of the redox properties of this interesting system, somewhat of a model system with two complementing interactions (electrostatic and aromatic stacking). The influence of the electrodeposition charge and current density on the properties of the polymer film is explored. The voltammetric measurements show that redoxactivity of the polypyrrole films doped with benzenesulfonate anions is quite high, and markedly depends on the thickness of the film. Experiments with bilayered films show that electrode surface has an important but limited impact on the formation of organized compact structures.

Electrochemical recovery of cadmium from spent Ni–Cd batteries

In this work, cadmium from spent Ni–Cd batteries is recycled. Ionic cadmium is recovery from acidic solution using a galvanostatic technique. Electrodeposition charge efficiency and deposit morphology depend on current density. Charge efficiency reaches up to 85.0% for a current density between 5.0 and 10.0 mA cm −2 and decreases with the increase in current density. Pore size decreases with the increase in current density.

Nanodiamond Thin Film Electrodes: Metal Electro‐Deposition and Stripping Processes

AbstractThe properties of a nanodiamond thin film deposit formed on titanium substrates in a microwave‐plasma enhanced CVD process, are investigated for applications in electroanalysis. The nanodiamond deposit consists of intergrown nano‐sized platelets of diamond with a high sp2 carbon content giving it high electrical conductivity and electrochemical reactivity. Nanodiamond thin film electrodes (of approximately 2 μm thickness) are characterized by electron microscopy and electrochemical methods. First, for a reversible one electron redox system, Ru(NH3)63+/2+, nanodiamond is shown to give well‐defined diffusion controlled voltammetric responses. Next, metal deposition processes are shown to proceed on nanodiamond with high reversibility and high efficiency compared to processes reported on boron‐doped diamond. The nucleation of gold is shown to be facile at edge sites, which are abundant on the nanodiamond surface. For the deposition and stripping of both gold and copper, a stripping efficiency (the ratio of electro‐dissolution charge to electro‐deposition charge) of close to unity is detected even at low concentrations of analyte. The effect of thermal annealing in air is shown to drastically modify the electrode characteristics probably due to interfacial oxidation, loss of active sp2 sites, and loss of conductivity.