bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solution Equilibria and Electroless Copper Deposition in Alkaline Formaldehyde-Containing Solutions
Authors: Norkus Eugenijus 
Published: February 2020

The industrial electroless copper plating solutions containing formaldehyde as reducing agent are known from the middle of this century and are widespread in the practice up to now. However, the investigation of this system remains actual because of its complexity, e. g.alkaline medium, hydrated form of formaldehyde (methanediol), Cu(II) complex compounds with different ligands, additives which improve the properties of the coatings obtained and/or protect from the reduction of copper(II) in the solution bulk. Moreover, various equilibria are possible including deprotonation of methanediol, Cu(II) complex formation, additional interactions between components of the solution.
The aims and tasksof this work were to investigate or define more precisely equilibria in conventional alkaline solutions of electroless copper deposition as well as influence of the nature of Cu(II) ligands on the copper deposition process.
This research report deals with the results obtained by means of dc-polarography, vis-spectrophotometry, voltammetry, potentiometry, pH-metry, 1H and 13C NMR spectroscopy, scanning electron microscopy, X-ray diffractometry and gravimetry.
The composition, stability and the values of the diffusion coefficient of Cu(II) complex compounds with ligands (EDTA, DTPA, pyridine-2,6-dicarboxylic acid and 4-hydroxypyridine-2,6-dicarboxylic acid, Quadrol, L(+)-, D(–)- and DL()-tartrate, glycerol, saccharose and OH- ions) which are used or usable in alkaline electroless copper deposition solutions were established. The formation of mixed complex compounds between Cu(II) complexonates and K4Fe(CN)6, as well as between Cu(II) tartrate complexes and methanediol was investigated. The interaction of methanediol with L(+)-tartrate alongside with the influence of the ionic strength and cation nature on the deprotonation of methanediol in alkaline solutions were studied.
The kinetic data on electroless copper deposition from solutions containing above-mentioned ligands is presented and the influence of the ligand nature on the process of electroless copper deposition is discussed.
Reaction Mechanism of Thiourea as Suppressor in Electroless Cu Deposition Process
Authors: Kunimoto Masahiro , Naito Takehiro , Nakai Hiromi , Homma Takayuki 
Published: February 2020

For more precise control of the electroless deposition process, reaction mechanisms of additives should be elucidated well. Particularly, in the case of the electroless deposition of Cu, behavior of thiourea (TU), which is one of the most widely used suppressor, molecular level understanding is significant. Although analyses of TU have been reported by numbers of researchers [1,2], its suppression mechanism has not been systematically understood. In this study we attempted to elucidate suppression mechanism of TU in electroless Cu deposition with formaldehyde as a reducing agent.
Since the electroless Cu deposition reaction involves both oxidation of formaldehyde and reduction of Cu2+ ion, the effect of TU on each reaction should be evaluated separately. For this, we employed “separated bath” system [3]; the bath without Cu2+ ion (oxidation bath), in which the only oxidation of formaldehyde proceeds, and the bath without formaldehyde (reduction bath), in which the only reduction of Cu2+proceeds, are connected with copper wire as shown in Fig. 1. The conditions of each bath are listed in Table 1.
When TU is added only to the oxidation bath, current density steeply decreased as shown in Fig. 2 (a), indicating that TU inhibits the oxidation of formaldehyde. On the other hand, when TU is added only to the reduction bath, current density slightly increased as shown in Fig. 2 (b), indicating that TU accelerates the reduction of Cu2+, probably due to the capturing effect of TU on Cu2+around the interface [4]. Overall, TU suppresses the Cu deposition reaction by inhibiting the oxidation reaction of reducing agent.
To elucidate the inhibition effect of TU on the reaction of formaldehyde, the adsorption states of TU and formaldehyde are calculated by DFT. Comparing these results, it is indicated that the adsorption energy of TU is much higher than that of formaldehyde. This shows that the adsorption of TU is much favorable on Cu substrate rather than that of formaldehyde. Hence, TU should inhibit the adsorption of formaldehyde by occupying the adsorption sites. Furthermore, from the DFT analysis, combined with SERS measurement, monomeric TU was indicated to adsorb on Cu surface via its NH2group because of the solvent effect.
Acknowledgements
This work was financially supported in part by Grant-in-Aid for Scientific Research (A) and “Development of Systems and Technology for Advanced Measurement and Analysis” program of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
References
[1] D. Papapanayiotou, R. N. Nuzzo, R. C. Alkire, J. Electrochem. Soc., 145 (10), 3366 (1998).
[2] G. M. Brown, G. A. Hope, D. P. Schweinsberg, P. M. Fredericks, J. Electroanal.
Chem., 380, 161 (1995).
[3] M. Kunimoto, K. Endo, H. Nakai, T. Homma, Electrochim.
Acta, 100, 311 (2013).
[4] J. S. Sallo, J. Kivel, F. C. Albers, J. Electrochem. Soc., 110, 890 (1963).
Kinetic Monte Carlo Studies of Enhanced Chemical Reactions on Nanoporous Electrodes
Authors: Sato Shutaro , Kaneko Yutaka 
Published: February 2020

Kinetic Monte Carlo studies of enhanced chemical reactions on nanoporous electrodes
Nanoporous electrodes have the effect of enhancing kinetically-limited electrochemical reactions due to the enlargement of electrode surface area. It has recently been reported that the confinement effect of reactants in the pores plays an important role for the enhancement of the reactions[1, 2]. By using these catalytic effect of nanoporous electrodes, the application to nonenzymic sensor (ex. glucose) has been explored[3]. The purpose of the present work is to study the effects of nanoporous electrodes on the enhanced chemical reactions on an atomic length scale by the kinetic Monte Carlo (KMC) simulation. We focus our attention on the confinement effect of reactants as well as the enlargement of the electrode area. We have developed a combination of KMC and grand canonical Monte Carlo (GCMC) for the multiscale simulation of the reactions and the mass transport in solution.
We have performed a series of KMC-GCMC simulations to study the correlation between the porous structures (cylindrical, random) and the enhancement of the reactions. The simulation system is a three-dimensional square lattice consisting of electrode, solution and replenishing region. Figure-1 is a schematic diagram of this system. Reactant particles are distributed in solution and their diffusion is simulated by random walk. The upper part of the solution is a replenishing layer to supply the reactant particles when the concentration becomes low as a result of the surface reactions. We consider a simple electrode reaction. It is assumed that reactants are removed on the electrode with a given rate constant. We consider two types of pore structures; cylindrical pore and random pore. The diffusion and reaction of the particles are simulated by KMC method. The replenishing layer is simulated by GCMC method.
We first confirmed that nanoporous electrodes enhance slow reactions compared to flat electrodes. The influence of the pore structures on the reaction mechanism is studied in detail. We also study the reaction of the mixture of slow and fast reactant particles as an application to the sensors.
References
[1] J.-H. Han, E. Lee, S. Park, R. Chang and T. D. Chung, J. Phys. Chem. C, 114, 9546-9553 (2010)
[2] S. Park, H. C. Kim and T. D. Chung, Analyst, 137, 3891-3093 (2012)
[3] S. Park, T. D. Chung and H. C. Kim, Anal. Chem., 75, 3046-3049 (2003)
Magnetic Bit Patterned Media Fabrication Using Block Copolymer Directed Assembly
Authors: Ruiz Ricardo 
Published: February 2020

Perpendicular magnetic recording media in excess of 1Tbit/in2 faces thermal stability and/or writeability challenges that are currently driving intense research in alternative technologies. Bit patterned media (BPM), in which magnetic bits are lithographically patterned as individual islands, stands as a promising technology for thermally stable, writable media. One of the main challenges of BPM lies in its lithographic specifications which push dimensions beyond those established for the conventional semiconductor industry roadmap. The most promising solution to the lithographic challenge can be found in directed self assembly of block copolymer films which has recently evolved as a viable technique to achieve sub-20nm lithography in time for BPM technology.
The periodic features naturally formed in block copolymer films display superior size uniformity at ultra-high densities, making them ideal lithographic masks to define the highly periodic data bits in the data sectors of hard disk drives for bit patterned media (BPM) technology at densities beyond 1Tbit/in2. Nanofabrication challenges towards bit patterned media, however, reach far beyond pattern formation at small length scales. The challenges faced in the fabrication of templates for BPM have spurred a set of important innovations in nanofabrication techniques such as the formation of geometries that deviate from the typical shapes naturally formed by block copolymers, as well as advances in high-fidelity pattern transfer and progress in scalability towards higher feature densities. In this presentation, we discuss some of these innovations. We demonstrate a process that combines directed self assembly with nanoimprint lithography to achieve rectangular patterns mounted on circular tracks. We will also discuss the impact of the nanofabrication process on the magnetic performance of the magnetic islands and the outlook for BPM technology. We will also explore additional innovations in nanofabrication techniques made possible by block copolymer lithography including opportunities in electroplating using self assembled masks.
Magnetic Alloy Plating with Hydroxymethyl-P-Tolylsulfone (HPT) Organic Additive
Authors: Sun Ming , Medina Jose , Sam Sopheak , Jiang Ming 
Published: February 2020

Additives play an important role in thin magnetic alloy electrodeposition since they impact the film grain boundary, the nucleation and growth mechanism. Consequently, they significantly determine the film properties.
In this study, we have evaluated a α-hydroxy sulfone compound as plating additive (Hydroxymethyl-P-Tolylsulfone or HPT was used as a case study) in CoNiFe and CoFe electrodeposition processes. From the chemical nature of HPT, the major drawback of this compound is its poor stability in aqueous medium in the presence of air. Analytical (HPLC) and electrochemical methods have been utilized to identify the compound decay mechanism and behavior. The HPLC spectrum of HPT and its decay by-products are compared to those of pure known compounds in Fig 1. With HPT added into CoNiFe and CoFe electrolytes, a strong grain refining effect was noticed in the deposits and the related film properties (magnetic, morphology and corrosion properties, etc.) have been characterized accordingly.
Nanoparticle Electrocatalysts for the Oxidation of Waste Lignin
Authors: Movil-Cabrera Omar , Garlock Michael , Staser John A 
Published: February 2020

Lignin is a large organic molecule and a primary waste from the pulping industry and biorefineries [1, 2]. Currently, lignin has little value other than as a fuel to generate heat. Lignin can, however, be used as a renewable raw material for a variety of value-added chemicals. Unfortunately, catalytic processes are difficult to implement for the degradation of waste lignin because selective oxidation is difficult and these processes produce an unacceptable amount of solid residue like char [2, 3].
Electrochemical processes, on the other hand, have several advantages over catalytic processes, including the use of mildly basic solvents as electrolytes, and control over the rate of reaction and the products. Thus, the electrochemical oxidation of waste lignin would be an ideal process to utilize this renewable raw material.
While there have been efforts related to the electrochemical oxidation of lignin, most work has focused either on expensive platinum electrodes or on low surface area, large metal electrodes. However, nanoparticle electrocatalysts can be developed that enhance the rate of electrochemical reaction through enhancement of electrocatalyst surface area and porosity.
We will report on our efforts to develop nanoparticle electrocatalysts with specific compositions and architectures for the electrochemical oxidation of lignin in weak alkaline solution. For example, Ni-Cu alloy nanoparticle electrocatalysts are suitable for the electro-oxidation of lignin in basic solution, as shown in Figure 1.

Figure 1. Electrochemical oxidation of lignin on Ni-Cu alloy nanoparticle electrocatalysts. Baseline is 1 M NaOH in the absence of lignin.

As shown in Figure 1, oxidation peaks in the presence of lignin occur around 0.03 V and 0.45 V vs. NHE that do not occur in the absence of lignin. Figure 1 indicates that lignin may undergo a complicated, multi-step oxidation process. For example, lignin may oxidize to one product at a lower potential, and that product may in turn oxidize to yet another product at higher potential. The oxidation potential and oxidation time (i.e., charge passed) affects the product distribution.
One of the most important aspects of the electrochemical oxidation of lignin in alkaline solution is the identification of the oxidation products. We will present GC/MS data that identify lignin oxidation products. This process could provide an economic way of reducing the organic waste from the pulping and biorefinery industries.

References.

1. A. French, “’Lignin’ May Be the Magic Word,” Innovation: America’s Journal of Technology Commercialization, June/July 2011.
2. C. Grestini, “Conversion of Lignin: Chemical Technologies and Biotechnologies,” EuroBioRef Summer School, Universita Degli Studi di Roma, Castro Marina, Lecce, Italy, September 21, 2011.
3. M. P. Pandey and C. S. Kim, “Lignin Depolymerization and Conversion: A Review of Thermochemical Methods,” Chemical Engineering and Technology, 34, 327-331 (1999)
Electrooxidation Treatment for Wastewater Sludge
Authors: De Leon Condes Cristina , Barrios Jose A , Becerril Elias , Barrera-Díaz Carlos , Roa-Morales G. 
Published: February 2020

Sludge produced during wastewater treatment, contain pathogens that increases the risks to human health. In particular, the density of bacteria and helminth eggs in sludge generated in Mexico significantly exceeds the levels reported in developed countries (Jimenez , et al. 2002 ; Jimenez, 2007). These microorganisms enter into the sewage system and due to its physicochemical properties tend to accumulate in the sludge during the wastewater treatment (Diaz Cruz, et al. 2009 ) .
Some studies have reported on the BDD electrooxidation for removal of emerging pollutants in secondary effluents (Frontistis, 2011), however, with respect to sludge, this process has been applied only for stabilization and conditioning (Drogui et al. 2013) but not for the removal of pathogens. This work presents the results obtained when electrooxidation with BDD electrodes was applied to sludge under laboratory conditions.
A batch cylindrical electrochemical reactor containing a pair of BDD electrodes (BDD film supported on a niobium substrate) was used for electrooxidation tests. Each electrode was 20.0 cm by 2.5 cm with a surface area of 50 cm2. Batch volumes of 0.3 L were treated in a 1.0 L glass reactor. A direct-current power source supplied the system with 0.5, 1.0 and 2.0 amperes, corresponding to current densities of 10, 20, and 30 mA/cm2. Sludge samples were mixed using a magnetic stirrer to reduce liquid-solid phase separation.
Figure 1 shows the COD removal as a function of the pH. Note that the best conditions are reached under acid pH.
References
Díaz-Cruz, M.J. García-Galán, P. Guerra, A. Jelic, C. Postigo, E. Eljarrat, M. Farré, M.J. López d Alda, M. Petrovic, D. Barceló. 2009. Analysis of selected emerging contaminants in sewage sludge. TrAC Trends in Analytical Chemistry Volume 28, Issue 11, Pages 1263–1275.
Jiménez, B. (2007). Helminth ova control in sludge: a review. Water
Science & Technology, Vol. 56, No. 9, pp. 147–155.
Jiménez, B., Maya, C., Sánchez, E., Romero, A., Lira, L. and Barrios, J.A. (2002) Comparison of the quantity and quality of the microbiological content of sludge in countries with low and high content of pathogens. Water Science & Technology, Vol. 46, No. 10, pp. 17–24.
Comparison of Rectangular and Cylindrical-Flux Reactors in Electrochemical Remediation of Mercury Polluted Soil
Authors: Robles Irma , Bustos Erika 
Published: February 2020

Mercury removal from soil is one of the most important approaches in the environmental field. In this way, electroremediation have shown a good alternative to remove it from soil. Electrochemical remediation is based on the generation of an electric field from the imposition of a direct current or potential using electrodes (anode and cathode), which are placed in pit excavated soil.
Two configuration reactors laboratory scale were tested in order to analyze the effect of current, flux, soil type, pH and conductivity. Both reactors include two titanium electrodes, separated 7 cm, and placed face to face in a 1D configuration. First reactor is a rectangular cell, and second reactor is a cylindrical-flux cell. In both cases same amount of soil was placed. Different potential values (5, 10, 15, 20 and 25 V) were tested in order to obtain the better conditions of electroremediation. All the experiments were done at room temperature and EDTA [0.1 M] was used as a complexing agent to improve electrochemical treatment.
Results indicated that in the rectangular reactor without flux, mercury moves toward the anode (+), by the presence of EDTA that forms a strong complex in a negative charge that promotes the movement of the complex ([EDTA-Hg]2-) to the electrode by the current application; pH and conductivity vary slightly in this experiments. The best condition is to apply a potential of 20 V, for a period of 1 h. At the end of the treatment passivation was observed in the electrodes at 20 and 25 V applied.
In the case of cylindrical reactor, flux of 2.5 and 6.5 mL·min were tested, this flux was imposed in a cathode-anode direction because of previous results. In this way, for the case of soil 1, a potential of 1 V shows same effectiveness as 25 V; but in the case of soil 2, 20 V are needed to remove most mercury amount. It depends on soil composition as organic matter content. Lower flux improves the current distribution. In this analysis pH and conductivity does not vary as in the case of rectangular cell.
Cylindrical-flux configuration improves the distribution of current and the efficiency of mercury removal. In this case no damage was observed in the electrodes, and pH and conductivity follows as initial values.
Improvement of the Performance of the Hydrodynamics in the Diluted Compartment of an Electrodeionization Reactor
Authors: Enciso-Pérez Rubi , Rodríguez-Torres Israel 
Published: February 2020

The hydrodynamic behavior of the electrodeionization reactor allows the improvement of the performance of the process as a whole. The challenge lies on the adequate modelling of the packed bed compartment, due to the particle size of the ion exchange resins.
The present study focusses on the improvement of the hydrodynamic behavior of the diluted compartment to achieve a plug flow in the diluted compartment of the reactor by adjustments in the geometry design via CAD.
The reactor, with 32cm2 ion exchange membranes, has two concentrated and one diluted packed bed compartment where the solution to be treated is introduced to the reactor and deionized while being in contact with the ion exchange resin.
Using CFD software, the existing geometry for the reactor was simulated and then subsequent variations were made to achieve a plug flow in the diluted compartment, minimizing the stagnant and channeling zones.
The results, allow the study of the velocity profiles in the compartment for the different geometries modeled and the selection of the configuration that allow the removal of the maximum quantity of ions from the inlet solution.
Beyond Chevrel Phase Mo6S8 : High Energy Density Mg Battery Cathodes
Authors: Mizuno Fuminori , Arthur Timothy S. , Zhang Ruigang , Ling Chen 
Published: February 2020

Rechargeable magnesium batteries have recently gained more and more attention for a possible candidate of post lithium-ion batteries, because of i) potentially high energy density ((3.0V x 2e- for Mg) / (4.0V x 1e- for Li) = 1.5), ii) low cost (high clarke number; Mg (1.93) vs. Li(0.006)) and iii) intrinsic safety (no dendrite growth for Mg, while needle-like dendrite for Li). In 2000, a great success of Mg battery was achieved by Prof. Aurbach in the system comprising Mg metal anode, Chevrel phase Mo6S8cathode and Grignard based electrolyte [1]. The prototype Mg battery can work very well over >2000 cycles. Guided by this discovery, intensive researches on anode, cathode and electrolyte materials have accelerated all over the world, to maximize the advantages of the Mg battery system.
Although there have many hurdles to be overcome in the Mg batteries, the biggest hurdle is that the cathode energy density stays much lower than expected. The Chevrel phase Mo6S8 is the only reported cathode material with good cyclability, but due to low operation voltage (1.2 V vs. Mg) and low capacity (122 mAh/g), it is theoretically difficult to realize the Mg battery which is competitive with lithium-ion batteries in term of energy density. Therefore, cathode materials having high operation voltage and high capacity are strongly desired. Previously, we worked on MnO2 cathodes and tried to understand its reaction mechanisms. Although MnO2 cathodes show higher average voltage (1.5 V vs. Mg) and high initial capacity (280 mAh/g) [2], they faced certain restrictions (i.e. structural deformation, thermodynamically preferred conversion reaction and resistive shell formation (Figure 1)) during magnesium ion intercalation into the host structure, resulting in a severe capacity fading during cycling [3,4]. Based on this knowledge, we have been currently researching solutions to such issues while continuously trying to find new cathode candidates. For example, CaFe2O4 phase MgMn2O4 [5], carbon cluster fullerene (C60) [6], amorphous vanadium oxide [7], and so on.
In this presentation, we will discuss about key challenges in improving the cathode performances of these materials and in further enhancing the energy density of Mg batteries.
References [1] D. Aurbach et al., Nature, 407 (2000) 724. [2] R. Zhang et al., Electrochem. Commun., 23 (2012) 110. [3] C. Ling et al., submitted for publication (2014). [4] T. Arthur et al., submitted for publication (2014). [5] C. Ling et al., Chem. Mater., 25 (2013) 3062. [6] R. Zhang et al., submitted for publication (2014). [7] T. Arthur et al., submitted for publication (2014).