bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving Mass Transport of Titanium Hollow Fibre Electrodes through Gas Flow Stimulated Hydrodynamics
Authors: Jong Ronald P.H. , Krzywda Piotr M. , Mul Guido 
Published: December 2020

Hollow fiber electrodes, also known as porous tube electrodes, creatively address common gas related challenges in electrochemistry. By purging gas through the electrode wall an intense three phase contact can be established along the entire electrode-electrolyte interface. The electrochemical behavior of the hollow fiber electrode has been hypothesized based on the CO2 reduction reaction on a copper hollow fiber electrode 1. It was however not studied to any significant extent. The electrochemical behavior of the hollow fiber electrode and it’s relevant parameters have now been clarified and studied in more detail.
In this study highly conductive titanium hollow fiber electrodes are used, since it is an attractive base electrode material for a great variety of electrochemical applications 2. These titanium based hollow fibers have an electrical resistivity (4.1-9.6 μΩ·m) 3 that is orders of magnitude lower than those previously reported in literature 4. This results from utilization of the two-step thermal decomposition of the polymer, which is required for the construction of an inorganic hollow fiber in a dry-wet spinning process 3.
The investigation of platinum electrodeposition onto titanium hollow fiber electrodes with different flow rates has proven exceptionally insightful with regard to understanding the electrochemical behavior of the hollow fiber electrodes. The effect of volumetric gas flow rate on the resulting platinum deposit is visualized through the platinum electrochemical surface area and SEM images (Figure 1). Looking beyond the volumetric gas flow rate it is found that the exerted pressure and the pore size distribution relate to the area depended flow rate and bubble frequency at a pore, which affect the platinum distribution. In order to deconvolute the mass transfer during the platinum electrodeposition process, the hydrogen evolution reaction and an Fe2+/3+-redox couple have been investigated. These experiments isolate mass transport as an electrical current response to flow rate in the cases of gas evolution and electron transfer in solution respectively. By drawing on analogues with the proven methods of porometry and rotating disk electrodes it was found that many aspects of the electrochemical behavior of hollow fiber electrodes can be explained. The Young-Laplace equation helps in matching pressure fluctuation to the chemical state of the electrode surface and following the principles of the Koutecký-Levich equation it is possible to describe the current changes resulting from gas flow rate.

Kas, et al. (2016). Nat. Commun., 7. DOI: 10.1038/ncomms10748

Devilliers & E. Mahé. (2007). Trends in Electrochemistry Research., 1. ISBN: 1-59454-457-3

P. H. Jong, et al. (2020). To be submitted.

David, et al. (2014). J. Membr. Sci., 139. DOI: 10.1016/j.memsci.2014.03.010

Figure 1
Adatom Surface Modification of Metal Nanoparticle Electrodes Though Underpotential Deposition for CO2 Electroreduction Catalysis
Authors: Carroll Mike 
Published: December 2020

The electrocatalytic CO2 reduction reaction to form higher order carbon-coupled products is a complex interplay of CO binding energies, kinetic rate-constant branching ratios, CO2 solubility, and pH gradients. The result of this wide, and often uncontrolled parameter space is a distribution of CO2RR products, especially in carbon-coupled reactions. Designing electrocatalysts that promote any of these parameters individually is an attractive route to not only build selective CO2RR catalysts, but also to provide the framework of design principals for selective electrocatalysis. To this end, systematically varying the electrode kinetics of CO2 reduction reactions on model system substrates through minor surface modifications is an informative approach for understanding this complicated reaction and how certain products can be expressed or suppressed.
Metal nanoparticle electrocatalysts are an interesting model system as recent advances in synthetic methods enable a large degree of size, shape, and facet control which allow systematic investigations of several well controlled parameters. Palladium nanoparticles are particularly interesting as Pd alloys with hydrogen prior to electroreduction catalysis in aqueous media. This alloying provides a continuous supply of reducing hydrogen equivalents for electrocatalysis. Pd surfaces can also be modified with submonolayer amounts of metal adatoms through underpotential electrodeposition. This surface modification can, in principal, tune both the binding energies of CO and the kinetic rate constants of the hydrogen evolution reaction, both critical parameters for CO2RR. This wide parameter space presents opportunities for applied and fundamental research. I will discuss recent results aimed at modifying the electrode kinetics of palladium nanocubes with 100 surface termination by modifying the surface with various metal adatoms in different amounts. I will show how Pd nanocube surface modification influences not only the surface, but bulk, hydrogen alloying properties of the nanocube as well.
Nickel Phosphide Electrocatalyst Prepared By Pulse Electrodeposition for Proton Exchange Membrane Water Electrolyzer
Authors: Yeon Kyurim , Kim Junhyeong , Ahn Sang Hyun 
Published: December 2020

Hydrogen is one of the main attractions for fossil fuels because it has several advantages. Since the combustion products are pure water, hydrogen is free from environmental pollution problems. And raw materials also use water, which is an infinite material on the earth, so there is no risk of exhaustion.
One of the ways to make high purity hydrogen is water electrolysis. Of the known elements, platinum is the most active material as an electrocatalyst in the hydrogen evolution reaction (HER). Platinum and platinum group elements have excellent activity, but there are several drawbacks such as low supply stability and high price due to its scarcity.
Considering industrial and economic aspects, electrocatalysts based on inexpensive and abundant transition metals such as Nickel, Copper and Molybdenum have been studied. Pure transition metals have weakness of poor activity and stability in HER. Various types of compounds, such as phosphide, carbide, nitride, and chalcogenide, were prepared to compensate for this.
In this study, a nanoparticle-type nickel phosphide (np/Ni-P) electroplated on carbon paper (CP) was used as the cathode of HER. When nickel phosphide is fabricated by electrodeposition, metallic nickel is deposited as well as nickel phosphide. If it is used intactly as an electrode catalyst, the performance and life of the catalyst are reduced as metallic nickel is oxidized in the HER process. So, additional leaching process was added to remove the metallic nickel over-plated.
In this study, nickel phosphide on nanoparticles with a large surface area was fabricated using a pulsed electroplating method that alternates electroplating and selective leaching. This makes it possible to produce a catalyst having a wider shape than that of which the surface area was electroplated and leached for the same time. In addition, this altenating process makes it possible to greatly reduce the amount of metallic nickel present in the catalyst, so helps increase the intrinsic activity of the catalyst because the proportion of phosphorus in the catalyst increases.
The finally produced catalyst was used as a cathode of a proton exchange membrane water electrolyzer (PEMWE) to investigate the results of a single cell, which showed reasonable activity.
Electrodeposited Transitional Metal-Based Electrocatalysts for Hydrogen Evolution Reaction
Authors: To Dung , Park Sun Hwa , Seyedmahmoudbaraghani Saba , Myung Nosang Vincent 
Published: December 2020

As the fossil fuel is continuously declining, the necessity of a sustainable and clean source of energy is increasing. Hydrogen has been considered as a potential alternative due to its “zero emission” when reacting with oxygen in electrochemical cells. In addition, hydrogen is also a promising energy carrier/ storage to compensate the intermittent nature of other renewable energy sources (e.g. sunlight, wind, and tides). However, majority of hydrogen production comes from the combustion of fossil fuel which doesn’t make hydrogen a practical sustainable energy. Electrocatalytic hydrogen evolution reaction (HER) in water electrolysis therefore has drawn considerable attention owing to water and oxygen as the “green” reactant and by-product respectively.
Early works with electrocatalytic HER involved noble metals (e.g. Pt) which is not cost-effective for industrial scale production. Therefore, transitional metal-based electrocatalysts (TMEs) have been intensively studied owing to the affinity of unpaired d-band electrons for chemisorption of hydrogen atoms. Among different strategies to improve the intrinsic properties of TMEs, coupling with other materials synergistically promotes the kinetics of HER. Nickel with minimum energy for hydrogen adsorption among various nonprecious metals exhibits the most efficient catalytic activities as a binary alloy with molybdenum in alkaline HER. Hydrogen spillover and averaging effect between the hydrogen adsorption energies of nickel and molybdenum facilitate the catalytic activity of nickel molybdenum alloy. On the other hand, transitional metal phosphides, especially cobalt with similar energy for hydrogen adsorption as nickel, have been considered as promising TMEs for acidic HER. With high electronegativity, phosphorus atoms can trap the positively charged protons and consequently enhance the dissociation of hydrogen. Moreover, dissolution of phosphorus-doped cobalt is less thermodynamically favored than that of cobalt, resulting in better electrocatalytic stability. To further enhance the HER catalytic performance, both types of electrocatalysts are synthesized at non-equilibrium by electrodeposition techniques to introduce chemical disorders and metaphases as well as to widen the range of composition. Different properties of deposits (e.g. composition, morphology, and grain size) can be tuned by controlling electrolyte composition and electrodeposition parameters.
Hybrid Electrodeposition of Ag-Graphene Composite Films on Cu Alloys for High-Conductive and Wear-Resistive Automotive Connectors
Authors: Sakaida Shizuka , Kure-Chu Songzhu , Matsubara Takashi , Liu Jiacheng , Hihara Takehiko , Yashiro Hitoshi 
Published: December 2020

In recent years, plug-in hybrid electric vehicles (PHEV) and plug-in hybrid vehicles (PHV) have become popular due to depletion of fossil fuels. At the tip of the wire harness, which is said to be the nerve of automobiles, there are numerous terminal connectors that are connected to various electronic devices, and the demand for their reliability is every increasing with the progress of PHEVs and PHVs. Considering the conductivity and heat generation, Cu alloys that plated with a highly conductive Ag film are commonly used. However, in addition to the problem of soaring costs due to the increased use of noble Ag, which is a, there is an important problem that the wear resistance of Ag is insufficient because of its adhesiveness during sliding and/or its soft nature, which has been unsolved yet.
In this study, we are aimed at fabricating a novel Ag-graphene composite films on Cu alloys though a facile hybrid electrodeposition. Here, graphene is used to function as an effective solid lubricant, while maintaining the conductivity of Ag matrix plating films that are indispensable to various automotive connectors. A commercial Cu alloy sheet was used as the base material. Graphene was produced by electrolytically exfoliating Graphite. A cyan-free Ag plating solution containing home-made graphene nano-flakes was adopted in electrodeposition. The thickness of the deposited films was designed to be 5 mm and controlled by depositing conditions. The resultant specimens were investigated by FE-SEM, EDX, GD-OES, Raman spectroscopy. The properties such as hardness, resistivity, and wear resistance were also evaluated.
Fig.1 shows the surface FE-SEM images of as-deposited pure Ag and Ag-graphene films. Both the pure Ag and the Ag-graphene composite film were smooth, consisting of nano-sized fine particles. It can be seen in the Ag-graphene composite film that, there were some areas where the particle size was slightly larger, and moreover, a hazy film-like material was observed on them, which was examined as C by EDS analysis. Fig. 2 shows the Raman spectroscopic measurement results of the pure Ag film and the Ag-graphene composite films. Compared to peak-less spectrum of pure Ag film, three typical peaks were detected in Ag-graphene composite film. The detected peaks are indexed to be D-band, G-band, and 2D-band from graphene, thus indicating the co-deposition of Ag and graphene flakes during the hybrid Ag electrodeposition and graphene electrophoretic deposition. Moreover, it was also found that the Ag-graphene composite films exhibited higher hardness and lower friction coefficient compared to the pure Ag film, thus confirming a promising candidate material for high-conductive and wear-resistive automotive connectors.

Figure 1
Electrochemical Deposition of Pd/Ag for Electrocatalytic Applications
Authors: Ispas Adriana , Bund Andreas 
Published: December 2020

Palladium-based alloys play an important role in many industrial applications, e.g. for the production and conversion of hydrogen (1). Palladium based catalysts show high reactivity both for the oxygen reduction reaction (ORR) and alcohol oxidation reaction respectively. One of the major drawbacks related to the hydrogen permeability in Pd is the blistering of Pd films at high concentrations of hydrogen. One effective method against this problem is to stabilize the Pd by alloying it (2). In general, alloys are promising materials because many of their chemical and electronic properties can be varied in a systematic way by changing the composition (1,2).
Pd/Ag alloys can act as selective hydrogenation catalysts. Furthermore, they are also used in electrical contacts. The alloys with the composition Ag0.23Pd0.77 are important with regard to hydrogen diffusion and these alloys are employed industrially as a H2 purification membranes. Pd/Ag nanoparticles also show promising applications as a novel activator for electroless copper deposition.
This paper will present the electrodeposition of Pd/Ag layers from different electrolytes with different complexing agents onto brass, mild steel, gold and glassy carbon (GC) substrates, in order to determine the optimum conditions and the parameters for the deposition of alloys with a tailored composition. Cyclic voltammetry was carried out in sulfuric acid containing methanol to determine the electrocatalytic activities of the deposited Pd/Ag structures. Further characterizations were performed using SEM coupled with EDX and XRF, in order to investigate morphologies and compositions of the alloys. Shiny deposits with a globular morphology and good adhesion were obtained. The ratio of Pd/Ag ion concentration in different electrolytes proved to be very important for the quality of the deposits. The addition of NH4NO3 improved the ionic conductivity of the bath, but it also acted as a complexing agent for Pd2+ and Ag2+. Without its addition, the Ag/Pd deposits will tend to grow in the form of dendrites and sheet crystals.
The Pd/Ag deposits showed good electrocatalytic activity for the oxidation of methanol. That would render them promising candidates as anode materials in direct methanol fuel cells.
(1) Y. Xiao, B. Weng, G. Yu, J. Wang, B. Hu and Z. Chen, J. Appl. Electrochem. 36 (2006) 807-812.
(2) B. Sturzenegger and J. Cl. Puippe, Platinum Metals Rev. 28 (1984) 117-124.
Bronze Electroplating: Stability, Nucleation and Growth Study of a New Green Formulation
Authors: Giurlani Walter , Fabbri Lorenzo , Vizza Martina , Marcantelli Patrick , Martinuzzi Stefano , Innocenti Massimo 
Published: December 2020

Bronze electroplating is a widely used process in the electronics and costume jewelry industrial sectors as an anti-corrosion coating and barrier layer against intermetallic diffusion. The study of this alloy is also essential for the realization of copper-zinc-tin sulfide (CZTS) compounds, a quaternary semiconductor with a growing interest for the realization of thin film photovoltaic devices. The galvanic baths currently on the market are alkaline with a high amount of sodium or potassium cyanide to complex the metal ions. Cyanide salts are extremely dangerous for their toxicity, blocking cellular respiration. For this reason, cyanides are considered a danger both for the environment as well as for the workers with whom it comes in contact. In this study, a new eco-friendly, acidic and cyanide-free formulation was developed for the deposition of the Cu-Sn alloy.
To achieve this goal, methanesulfonic acid (MSA) was chosen as electrolyte, which is biodegradable as part of the natural sulfur cycle. Various recipes have been evaluated to obtain a solution that was stable over time and that did not lead to the precipitation or oxidation of its components. Copper sulphate, copper methanesulfonate and tin methanesulfonate solutions were used as precursors of the metals [1]. As stabilizing additives nitrilotriacetic acid (NTA) and 2-picolinic acid (2PA), complex agents for copper, and hydroquinone (HYD), antioxidant agent for tin, were evaluated. The composition of the films, obtained both by potentiostatic and galvanostatic deposition, were analyzed by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) and, to investigate the structural phases of the deposits, XRD measurements were carried out. Finally, nucleation and growth as a function of the concentration of thiourea (TU) and potassium and sodium tartrate (PST), regulating additives for the deposition of copper and tin, respectively, were studied by chronoamperometric methods, in order to achieve progressive growth and therefore a lucid deposit. The present study funded by the PRIN Project (“Progetti di Ricerca di Rilevante Interesse Nazionale”), “Novel Multilayered and Micro-Machined Electrode Nano-Architectures for Electrocatalytic Applications (Fuel Cells and Electrolyzers)”, grant number 2017YH9MRK.
References:
[1] Fabbri, L. et al. Electrodeposition of White Bronzes on the Way to CZTS Absorber Films. J. Electrochem. Soc. 167, 022513 (2020). 10.1149/1945-7111/ab6c59.
Influence of Plating Conditions on Nickel-Chromium Alloy Electrodeposition
Authors: Ispas Adriana , Waibel Andreas , Fritz Mathias , Bund Andreas 
Published: December 2020

Nickel-chromium alloys present high corrosion and high creep resistance. Due to the large difference between the standard potentials of the two metals, E0(Ni2+/Ni)=-230 mV and E0(Cr3+/Cr)=-760 mV, the alloy composition usually strongly depends on the current density chosen for deposition, on the nickel concentration in the electrolyte and the electrolyte temperature.
The electrodeposition of chromium from the trivalent oxidation state is more challenging compared to its hexavalent state. In aqueous solutions Cr(III) ions form complexes some of which have a very low ligand exchange rate. Thus, electrochemical deposition is difficult or only possible at a very slow deposition rate. In addition to the aquo complexes, complexes can also be formed with the anion of the corresponding metal salt. Normally, complexing agents, such as carboxylic acids, are added to the electrolyte in order to increase the deposition rate.
This paper will present recent results from authors’ lab on the electrodeposition of Ni-Cr alloys from aqueous electrolytes containing Cr(III) salts. The effect of formic and oxalic acids on the qualities of the deposits was investigated, as well as the influence of the deposition technique (direct or pulse plating), current density, nickel concentration in the electrolyte, temperature of the electrolyte, and the hydrodynamic conditions.
We could show that the chromium content in the deposits can be easily tuned via the composition and temperature of the electrolyte, and the current density. At high current densities and low nickel concentrations, chromium-rich layers with up to 64 wt-% chromium could be deposited. An increase in the temperature led to a significant decrease in the chromium content of the deposits. The layers grow compactly and show a globular structure. The deposited films changed from a crystalline to an amorphous structure with increasing chromium content.
Electroplating and Surface Analysis
Authors: Fabbri Lorenzo , Piciollo Emanuele , Fontanesi Claudio , Giurlani Walter , Mencherini Giulia , De Luca Antonio , Passaponti Maurizio , Innocenti Massimo 
Published: December 2020

The interest in scientific research within the metal finishing sector is growing. The demand for durable metals and adaptable manufacturing processes are increasing across a wide range of applications, from aerospace and automotive to machinery and jewelry. An essential step in the production line is the surface engineering of metals, as this determines the final appearance and functionality of a product. Therein electroplating is recognized as a mature technology allowing the low cost fabrication of defined surfaces with extensive property profile. Galvanic electrodeposition accounts today for almost 40% of the global market value share with North America and Western Europe leading the scenery. Although technological and processing advancements occurred in the past forty years, industrial firms are still struggling to provide solutions to corrosion protection as well as reduction of toxic wastes. Specifically, large-scale industrialization of electroplating techniques will continue to be limited by strict environmental regulations. Due to adverse ecological impacts, the adoption of plating processes involving toxic metals such as lead or cadmium is prohibited. Moreover, price volatility of the highly demanding electroplated materials gold, copper and nickel is expected to impact the market share for more than 60% by 2026.
In that respect, alloy plating offers better answers in terms of economic growth and environmental sustainability due to fine tuning composition, morphology and crystallinity [1]. Here, current trends on alloy electrodeposition research are reviewed highlighting open challenges and process innovations from an industrial perspective. The main categories of alloy compounds are presented and the most important properties for the manufacturing process discussed. Particular attention is devoted to advances in industrial quality control and viable solutions for the reduction of precious metal content in electroplated accessories as well as replacement of cyanide and nickel baths with non-toxic compounds. The present study funded by the PRIN Project (“Progetti di Ricerca di Rilevante Interesse Nazionale”), “Novel Multilayered and Micro-Machined Electrode Nano-Architectures for Electrocatalytic Applications (Fuel Cells and Electrolyzers)”, grant number 2017YH9MRK.

References

[1] W. Giurlani, M. Innocenti et all. , Review, Coatings 2018, 8(8), 260.