bluuebunny/crossref_metadata_2025 huggingface dataset:
Tannins As Active Material for Energy Storage Applications
Authors: Lemieux Julien , Masson Alexandre , Santato Clara
Published: May 2020

The increasing demand for sustainable energy storage devices has driven the research on redox-active biosourced materials. Quinone-based tannins are present in the waste of the forest industry. Here we report a study on two molecules belonging to the tannin family, tannic acid (TA) and catechin (Ctn). An increase in the energy density of 835% for Ctn on activated carbon paper current collectors, in symmetrical configuration has been observed in aqueous electrolyte. Interestingly, in galvanostatic conditions, the surface of the carbon current collector undergoes changes that increase its capacity by two orders of magnitude. The resulting synergistic effect of the activation of the carbon surface and presence of redox active tannins is beneficial for the performance of the storage device. Work is in progress to improve the device cyclability (stability).
Oxygen-Retentive Coatings for High-Voltage Cathodes
Authors: Persson Kristin A.
Published: May 2020

Using first-principle calculations we rationalize the effectiveness of surface coatings and dopants for oxygen retention at the surface of high-voltage cathodes. We explore amorphous coatings by implementing a “liquid-quench” process, in which heating, equilibration, and quenching are done through series of AIMD simulations. Using a density-based spatial clustering to differentiate the vibrational and translational motions for Li and O trajectories, we analyze the correlation between local environment and diffusion. To evaluate each dopant’s ability to suppress the surface oxygen loss, we calculate the relative oxygen release energy during delithiation with respect to the pristine cathode phase. Insights based on the atomic structure, and stability against high-voltage delithiation is considered and recommendations towards improved systems are made.
Impacts of Solute and Solvent Coordination on Concentrated-Electrolyte Transport
Authors: Wang Andrew , Fawdon Jack , Hou Tianhong , Pasta Mauro , Monroe Charles W.
Published: May 2020

Super-concentration of electrolytic solutions has been hypothesized as a route to improve battery performance [1]. To predict electrolyte behavior accurately in superconcentrated systems, one must account for their fundamentally different molecular structures. Interactions between species such as ion pairs in concentrated electrolytes may impact the transport laws governing diffusion, migration, and convection, and solute-volume effects may be large because the solution volume fraction occupied by salt is extremely high.

Transport phenomena related to solute and solvent structure, such as Faradaic convection and the excluded-volume effect, can have appreciable impact or even dominate in the superconcentrated regime [2]. In very concentrated electrolytes, convection can be important because when dissolved salt occupies a large volume fraction of the liquid, salt flux across the boundary of a solution drives a bulk solution velocity through overall mass continuity. Experiments demonstrate that at high concentration, viscosity no longer determines ion mobility, i.e., the Stokes–Einstein relation fails. The dynamics of ion-pair formation and salt association/dissociation kinetics both can impact the availability of charge-carrying species in an electrolyte. Experimentally, Faradaic convection can be quantified by combining densitometry with electrochemical measurements. Ion speciation and extent of dissociation can be quantified with spectroscopic techniques.

Newman’s application of Onsager–Stefan–Maxwell theory to electrochemical transport considers solute/solute interactions neglected in Nernst–Planck dilute solution theory [3]. We will add to this perspective by discussing how solute-volume effects and ion-association equilibria additionally influence apparent flux-explicit transport properties such as conductivity, diffusivity and transference number [4].

[1] Yamada, Y., Wang, J., Ko, S., Watanabe, E. & Yamada, A. Advances and issues in developing salt-concentrated battery electrolytes. Nat. Energy
4, 269–280 (2019).

[2] Liu, J. & Monroe, C. W. Solute-volume effects in electrolyte transport. Electrochim. Acta
135, 447–460 (2014).

[3] Monroe, C. W. & Delacourt, C. Continuum transport laws for locally non-neutral concentrated electrolytes. Electrochim. Acta
114, 649–657 (2013).

[4] Hou, T. & Monroe, C. W. Composition-dependent thermodynamic and mass-transport characterization of lithium hexafluorophosphate in propylene carbonate. Electrochim. Acta 135085 (2019).

Figure 1
Evolution of Molten Salt Electrolysis in Titanium Production Process
Authors: Yamaguchi Makoto
Published: May 2020

The Titanium industry uses the Kroll process where titanium sponge is produced from the reduction of titanium tetrachloride by magnesium metal. The byproduct of this redox reaction is anhydrous molten magnesium chloride which must be reduced back to magnesium metal to complete the cycle.

Since the early sixties Osaka Titanium technologies Co., Ltd has developed monopolar and multipolar magnesium electrolysis cells which have been used in the Kroll process.

Monopolar cell has graphite anode and ferrous cathode, whereas multipolar cell has plural graphite bipolar electrodes between graphite anode and ferrous cathode. A magnesium nucleation and growth phenomenon on the graphite bipolar electrodes is different from that on ferrous cathode. Magnesium particles produced on the graphite bipolar electrodes are very fine, which leads to easy back reaction and difficult collection of them. OTC solved this problem and achieved high productivity, energy saving by halves and plant environmental upgrading.
Self-Activation of TiO2 Nanotubes for Photocatalytic H2 Generation
Authors: Schmuki Patrik
Published: May 2020

TiO2 and particularly its anatase form, is one of the most widely studied oxide semiconductors for photocatalytic production of H2 from aqueous solutions.In anatase, the conduction band is situated at an energetic position that allows the transfer of photogenerated electrons to aqueous media and thus the conversion of H+ into H2. Moreover, TiO2 provides an almost unique high resistance against chemical and photocorrosion. On the other hand, photocatalytic H2 production from aqueous electrolytes shows very slow kinetics on all TiO2 surfaces. Therefore, typically decoration of titania with co-catalysts is used to accelerate the H2 evolution kinetics. Most effective co-catalysts are costly noble metals, such as Pt, Pd, or Au. Economically it is of great interest to develop means and approaches to reduce the use of such costly co-catalyst. In the presentation, we discuss efficient noble-metal-free approaches for catalyzing photocatalytic hydrogen generation. A particularly interesting approach is provided by defined defect engineering of anatase. Specific shallow Ti3+ states can promote the generation of photocatalytic H2. Most spectacular is that these catalytic sites can be formed by photoinduced reduction. In other words, under suitable illumination conditions it is possible to create, in situ, energetically suitable Ti3+ states that then act as an intrinsic co-catalyst for photocatalytic H2 evolution. As a result, both co-catalytic formation of active sites and photocatalytic H2 formation is observed. I.e., with increasing illumination time, a light‐induced self‐amplification of the photocatalytic H2 production rate occurs. The effect is characterized by electron paramagnetic resonance (EPR) spectroscopy, reflectivity, and photoelectrochemical techniques. The origin of the self‐activation and amplification behavior observed for anatase nanoparticles and nanotubes will be discussed in the presentation.
The Oxygen Reduction Reaction Kinetics on a Platinum /Graphene Surface
Authors: Diankov Georgi , Hong Soonwook , Xu John , Pande Vikram , Park Joonsuk , Sinclair Robert , Visvanathan Venkatasubramanian , Goldhaber-Gordon David , Prinz Fritz B
Published: May 2020

The oxygen reduction reaction (ORR) is rate-limiting in polymer electrolyte fuel cells over a wide range of overpotentials. To improve our understanding of the underlying physics and chemistry of ORR, we created a model system with atomically-ordered interfaces that allows us to distinguish between bulk and electronic effects on catalytic behavior. Specifically, we developed a facile way of growing thin, epitaxial Pt nanostructures on graphene, which serves as both growth substrate and electrode. Rotating disc electrode measurements showed a high specific activity relative to platinum on glassy carbon. The enhanced ORR activity was observed despite consistent measurements that show a small electrochemically-active surface area arising from the fact that virtually all carbon atoms in monolayer graphene are surface atoms. This talk will address the reasons for the increase of ORR activity in view of the new ground state of atomically thin platinum on graphene.
On the Nucleation Loop in Cyclic Voltammetry for Electrodeposition of Pd Thin Films
Authors: Pise Mangesh T. , Chatterjee Arnomitra , Singh Ram. N. , Kashyap Bhagwati P. , Tatiparti Sankara Sarma V.
Published: May 2020

Pd is an excellent catalyst layer for Mg-based thin films for hydrogen storage. Cyclic voltammetry (CV) for Pd deposition on Au in PdCl2+HCl solution between +1.100 and –0.400 V vs Ag/AgCl (3M NaCl) exhibits nucleation loop (NL). NL is characterized by higher cathodic current density (j) in reverse scan versus that in forward scan. This work addresses the question “Why does nucleation loop occur during CV?” using substrate conditions and overpotential (η). Since it is difficult to estimate η during CV, the substrate conditions similar to those within NL are reproduced by potential sweep in (i) forward and (ii) complete forward+reverse scans up to a representative potential (+0.330 V) within NL. These scans produce substrates FS and RS with partial and significant Pd coverage, respectively. Eventual potentiostatic electrodepositions (ED) at +0.330 V on these substrates initially show similar j trends as in NL, replicating Pd deposition during CV. η during ED is estimated by equilibrium potentials and potential drop due to solution resistance (R
s) from electrochemical impedance spectroscopy at +0.330 V. The estimated η is higher on RS, supporting higher j during electrodeposition on RS and reverse scan of CV within NL. Electrochemical and morphological analyses together suggest that Pd deposition on FS is nucleation driven; that on RS is growth driven, which help in revealing the metal deposition mechanisms.
The Role of Graphene in the Growth of Pd and Pt Nanostructures Using Surface Limited Electrodeposition
Authors: Drexler Matthew , Alamgir Faisal M. , Unocic Raymond R
Published: May 2020

Surface limited redox replacement is an attractive catalyst synthesis technique due to its ability to precisely control the amount of deposited metal, but the deposition is generally limited to metallic surfaces. It would be preferable to use this technique directly on conductive carbon-based support materials to reduce metal loading and improve adhesion between catalyst and support, but films are difficult to achieve due to the low surface energy of carbon materials. Metal deposition via this technique is still possible, as this study demonstrates with Pd and Pt on graphene, producing nanoparticles and low aspect ratio nanostructures. Pd favored a combination of agglomerated nanoparticles and Cl-based films that were highly influenced by the alignment of the graphene as seen in STEM. Pt tended to form isolated nanostructures with an average width-to-height aspect ratio of 2. Lattice planes are typically visible in STEM images, and, through their structure and orientation, both types of structures show signs of epitaxial relation with graphene as a growth substrate.
New Insight into Electrochemical Nucleation and Growth of Metal Nanoparticles through Multiscale Approach
Authors: Mamme Mesfin Haile , Łukaczyńska-Anderson Monika , Mernissi Cherigui El Amine , Hubin Annick , De Proft Frank , Ustarroz Jon
Published: May 2020

Nowadays, supporting metal nanoparticles have attracted much interest due to their fascinating physio-chemical properties and potential application in fuel cells, sensors, catalysis, solar to fuel devices and among others. One of the interesting issues from engaging physiochemical properties of supporting nanoparticles is to understand their nucleation and growth mechanism in order to get a good control of their structural and morphological parameters. Although studied for decades, however, the full details are still out of reach [1]. In this presentation, we will first review the classical theory of nucleation and growth and secondly present our recent finding and theoretical development on the growth of an isolated metal nanoparticle using a combined experimental (linear sweep voltammetry, chronoamperommetry and FESEM) and multiscale modelling approach [2-5]. In this presentation we focused on the modelling approach. The use of such a multiscale framework allows studying nanoscale electrochemical deposition as a whole, without the need to assume a dominant growth mechanism such as diffusion or kinetic control [2-5]. The simulation results reveal that the existing theory of nucleation and growth is only valid for some specific conditions. Some of the findings will be discussed in this presentation.

References

[1]. Ustarroz, J., Hammons, J. A., Altantzis, T., Hubin, A., Bals, S., & Terryn, H. (2013). A generalized electrochemical aggregative growth mechanism. Journal of the American Chemical Society, 135(31), 11550-11561.

[2]. Mamme, M. H., Dolgikh, O., Ustarroz, J., Simillion, H., Terryn, H., & Deconinck, J. (2016). A finite element simulation of the electrochemical growth of a single hemispherical silver nucleus. Electrochimica Acta, 197, 307-317.

[3]. Mamme, M. H., Deconinck, J., & Ustarroz, J. (2017). Transition between kinetic and diffusion control during the initial stages of electrochemical growth using numerical modelling. Electrochimica Acta, 258, 662-668.

[4]. Mamme, M. H., Köhn, C., Deconinck, J., & Ustarroz, J. (2018). Numerical insights into the early stages of nanoscale electrodeposition: nanocluster surface diffusion and aggregative growth. Nanoscale, 10(15), 7194-7209.

[5]. Cherigui, E. A. M., Sentosun, K., Mamme, M. H., Lukaczynska, M., Terryn, H., Bals, S., & Ustarroz, J. (2018). On the control and effect of water content during the electrodeposition of Ni nanostructures from deep eutectic solvents. The Journal of Physical Chemistry C, 122(40), 23129-23142.
Plasmonic Photovoltaics Enabled By Single-Crystal Metal Films and Nanostructures
Authors: V.-Grayli Sasan , MacNab Finlay C. , Zhang Xin , Kamal Saeid , Leach Gary W.
Published: May 2020

In contrast to conventional photovoltaic devices which rely on bulk semiconductor material absorption and separation of electron-hole pairs, surface plasmon-based solar energy harvesting employs rectifying metal/dielectric interfaces to capture light and separate charges. Here, we describe the requirements for efficient hot electron extraction in plasmonic photovoltaic devices and demonstrate a new scalable and environmentally friendly electroless deposition method for single crystal epitaxial noble metals films and nanostructures. The method produces ultra-smooth, low loss, single-crystal noble metal films ideal for subtractive patterning of nanostructures through ion beam milling, and high definition, sub-wavelength single crystal nanostructures through lithographic patterning methods. We describe the nucleation and growth of these metal films and nanostructures in the absence and presence of anionic shape-control agents and examine the role of specific anions in determining the resulting film and nanostructure morphologies via scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). These effects have been exploited to yield large area patterned, and shape-controlled nanoarrays of single crystal metal nanostructures for plasmonic and metamaterial applications. These approaches offer new and cost effective routes to achieve crystalline, shape-controlled surface nanostructure to enable efficient hot electron extraction for energy harvesting applications.
In-Situ Raman and DFT Analyses of ZnO Formation Reaction at Zn Negative Electrodes during Discharge Processes
Authors: Kunimoto Masahiro , Yanagisawa Masahiro , Homma Takayuki
Published: May 2020

Zn is of interest as a promising material for a negative electrode to be implemented in next generation rechargeable batteries. However its morphological changes, such as mossy-like structural growth or dendritic growth, which bring about serious degradation of the battery, are still a major issue. Such changes of the electrode surface are accompanied with the discharge reaction, which is expressed as Zn + 2OH- → ZnO + H2O + 2e-. This indicates that molecular level mechanisms of ZnO formation reaction are necessary to be investigated, to solve the issue of the undesirable electrode surface changes. We have recently shown the growth behavior of ZnO deposits by using in-situ Raman spectroscopy1. This paper describes the ZnO formation behavior during the discharge process in detail, based on the results of the Raman spectroscopy with DFT.

In-situ Raman spectroscopy was performed during the chronoamperometry for the ZnO formation. Our measurement cell is made up of a three electrodes system, in which all the electrodes is Zn. As the system approached the passivation, a strong peak around 400 cm-1 appeared, which represents the ZnO crystal structure formation. This suggests ZnO leads to the passivation of electrode surface. Furthermore, it turned out that the peak of ZnO crystal structure is not so stable: the peak could show blinks within several tens of seconds. This indicates that ZnO formation should go through atomic level structural changes with high flexibility after the deposition. The DFT calculation explains this from the molecular level viewpoint. It suggests Zn electrode significantly decreases the surface diffusion barrier of chemical species. The trend seen here is also shown in our other DFT results, in which Zn surface structure itself is also variable. The character of Zn, which allows flexible structural changes, might govern the growth behavior on Zn electrode surface.

This research was partially supported by the “Development of Systems and Technology for Advanced Measurement and Analysis”, and the “Research & Development Initiative for Scientific Innovation of New Generation Batteries (RISING 2)” from the New Energy and Industrial Technology Development Organization (NEDO) of Japan.

1. T. Otani, T. Yasuda, M. Kunimoto, M. Yanagisawa, Y. Fukunaka and T. Homma, Electrochim. Acta, 395, 90 (2019).
Texture and Bandgap Tuning of Phase Pure Cu2o Thin Films Grown By a Simple Potentiostatic Electrodeposition Technique
Authors: Farhad Syed Farid Uddin , Hossain Mohammad Moazzem , Tanvir Nazmul Islam , Islam Suravi
Published: May 2020

Phase pure Cu2O is one of the most desirable p-type absorber materials for ZnO based all-oxide solar cell because of its reported direct bandgap(~2.17 eV) and a suitable band alignment with n-type ZnO electrodes. Highly textured phase pure Cu2O thin films have been grown by a simple electrodeposition technique with varying cathodic potentials (-0.3 to -1.0 V) using Fluorine-doped Tin Oxide (FTO) substrates as working electrodes and a carbon rod as a counter electrode immersed in an alkaline aqueous electrolyte held at ~60 0C for 40 min. The surface morphology, structural, optical properties of the as-deposited Cu2O thin films were characterized by Scanning Electron Microscopy (SEM), Surface profiler, X-ray diffraction (XRD), and UV-Vis-NIR Spectroscopy respectively. SEM micrographs revealed that the deposited thin films coherently carpet the underlying substrate and composed of sharp faceted well-define grains having size in the range of 0.5 – 1.0 µm . XRD analyses showed that all films are composed of polycrystalline cubic Cu2O phase only and have average crystalline domain size in the range 30 – 73 nm. The preferred crystalline orientation of phase pure Cu2O films were found to be changing from (200) to (111) with increasing cathodic potentials and showed highest (111) and (200) crystalline texture coefficient while grown at -1.0 and -0.8 V respectively. The estimated optical bandgap of the as-grown samples were found in the range (2.00 – 2.20) eV consistent with the previously reported results and the variation of the optical bandgap could be attributed to the variation of the film thickness. The performance of copper oxide films was tested by estimating LED ‘ON/OFF’ modulated surface photovoltage into a photoelectrochemical cell at zero bias voltage and was found to be reasonable to integrate them into optoelectronic devices.
Thermodynamics and Electrochemistry of Thermally Regenerative Ammonia Batteries
Authors: Hall Derek M. , Cross Nicholas R , Lvov Serguei N. , Logan Bruce E. , Rau Matthew J
Published: May 2020

Deep cuts to global carbon emissions are only possible with a dramatic increase in energy storage capacity. However, the cost of the storage options available hinders the timely deployment of the necessary energy storage. Promising supplements to conventional storage are thermally regenerative ammonia batteries (TRABs), which have an additional advantage of being able to capture low-grade waste heat into dispatchable electricity for the grid. This new battery technology can potentially provide power on demand using low-cost chemistries and waste energy sources relative to their purely electric battery counterparts.

Most of the research to date for TRABs has been proof-of-concept in nature. As such, little is known about how the electrolytes used in these devices impact their theoretical energy storage capacity. Here we present the general principles of TRABs from an electrochemical and aqueous chemistry perspective. Energy storage density values and Eh-pH diagrams are presented to highlight key factors that govern these complex but versatile energy storage devices. Ag-based and Cu-based TRABs are discussed, and some experimental data confirming the conclusions of the Eh-pH diagrams are presented.
Synthesis of Ce-V-Mo Oxide Nanocomposite for High Performance All Solid State Asymmetric Supercapacitors (ASSASs)
Authors: Mawari Nemi Chand , Meher Sumanta Kumar
Published: May 2020

The depletion of non-renewable resources has prompted the continuous development of various energy storage systems to manage the world’s increasing demand for energy. Among the well-known energy storage systems, supercapacitors (SCs) exhibit superior performance because they can store more energy than conventional capacitors and have a higher power density than batteries. In this context, we have strategically synthesized ternary Ce-V-Mo oxide (CVMO) nanocomposite and directly utilized it in all solid state supercapacitor device. The phase purity, element composition and surface morphology were characterized by PXRD, EDS, FESEM, HRTEM and XPS measurements. The pseudocapacitive charge storage efficiency of CVMO was thoroughly studied by CV, GCD and EIS measurements. The CVMO offers a specific capacitance value of 5484 F g–1 at scan rate of 5 mV s–1 and 4330 F g–1 at a current density 4 Ag–1. The CVMO also retains ~87% of specific capacitance at a high current density of 20 A g–1. The EIS study shows low solution and charge transfer resistance of CVMO. An ASSAS device fabricated using N-rGO as the negative electrode material shows high rate capacitance, and superior energy density at elevated power density condition. The results presented here is significant in the context of developing high performance ASSASC devices for numerous technological viability.1-5
Cobalt/Chromium Carbide Composite Coatings Applied By Brush Plating for Use As an Alternative to Hard Chrome
Authors: Thomas Joshua David , Milosevic-Popovich Danijela
Published: May 2020

Due to increased concern for both environmental and worker safety from governments around the world, numerous significant industrial chemicals are being phased out of production processes. One example is the use of hexavalent chromium compounds for the electrodeposition of hard chrome. Electrodeposited chrome is typically used for improved hardness, lubricity, wear resistance, and corrosion resistance. This work will support the use of a metal matrix composite composed of cobalt and chromium carbide particles as an alternative for chrome coatings deposited from hexavalent chromium compounds.

Metal matrix composite (MMC) coatings consist of two phases co-deposited during plating: a continuous metal phase such as cobalt and small (<100 µm) particles of another chemical species distributed throughout. The physical qualities of the composite (such as hardness) are strongly dependent on the ratio and distribution of the two constituent phases. The composition of the plating solution and the parameters used during plating both play important roles in the composition and quality of the final deposit.

While most research has focused on applying metal matrix composites by tank electroplating methods, this presentation will focus on applying the coating via brush plating. Brush plating is a portable electrodeposition technique where solution is applied to the part by a plating solution saturated sleeve on the anode when contact is made to a localized area. Brush plating operations typically use less masking when plating small areas of a larger part. Less solution is needed because the part does not need to be immersed. And the brushing action allows for faster solution replenishment at the electrode surface.

During this presentation, attendees will be shown examples of a matrix material of cobalt co-deposited with either 1 µm or 6 µm chromium carbide particles. Attendees will learn how the concentration of the particle in solution determines the range of particle incorporation; as well as understand how tailoring the plating parameters to the system of particle and matrix is vital to creating a deposit for their specific characteristics.

References:

F. C. Walsh and C. Ponce De León, T. I. Met. Finish., 92, 83-98 (2014)

H. Xiao and S. Clouser, Plating Surf. Finish., 97, 44-51 (2010)

L. I. Arrom, thesis, Cranfield University, Cranfield, UK (2017)
The Interesting Complicacy of the New Age Metallic Coatings with Carbonaceous Additives
Authors: Arora Sweety , Srivastava Chandan
Published: May 2020

Metallic coatings have been traditionally used to protect the underlying substrate against corrosion. Recent reports have illustrated that use of carbonaceous material such as graphene, graphene oxide, carbon nanotubes as additives in conventional coating have led to significant enhancement in the corrosion resistance behaviour of the composite coatings. In this talk, the author will discuss the evolution of microstructure, morphology, phase constitution and corrosion behaviour of electrodeposited ZnCo coatings as a function of the amounts of graphene oxide contained in them. The as-deposited ZnCo-graphene oxide composite coatings were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDS). XRD based analysis of the coatings revealed that all the coatings contained Zn phase along with intermetallic phase (Zn10.
63Co2.34). A gradual increase in the volume fraction of the intermetallic phase was observed upon graphene oxide addition. Morphological characteristics and changes in the surface roughness were studied using SEM and AFM. A compact and smooth morphology was observed for initial graphene oxide additions while a higher graphene oxide concentration produced surface cracks due to graphene oxide agglomeration in the electrolytic bath. Weight loss measurements of control sample containing only the intermetallic phase revealed that the intermetallic was more corrosion resistant. The coatings were studied using electrochemical impedance spectroscopy (EIS) in 3.5 wt. % NaCl to understand the characteristics of corrosion product layer. Corrosion current in the coatings was found to decrease for initial graphene oxide addition while for higher additions a sudden increase in corrosion rate was observed. The impermeability of the graphene oxide and a relative increase in the volume fraction of nobler intermetallic phase lead to the initial reduction in corrosion rate. While, after an optimum graphene oxide addition which yielded the lowest corrosion rate, the incorporation of agglomerated graphene oxide lead to cracks and surface defects primarily due to non-uniform deposition. The surface morphology was analyzed using SEM after they were exposed to the electroactive media (3.5 wt.% NaCl). A continuous zinc dissolution was observed in the case of pristine ZnCo coatings while formation of pits was evident for maximum graphene oxide addition.

Figure 1
AC Voltammetry for Metal Electrodeposition Studies
Authors: Caldwell Andrew Harvey , Allanore Antoine
Published: May 2020

Analytic solutions are derived for the alternating current voltammetry (ACV) harmonic waveforms of electrodeposition reactions where the surface activity of a metal species is constant. Reversible and quasi- reversible charge transfer kinetics are considered, as well as the effects of ohmic drop and double layer charging. It is shown that ohmic drop produces a characteristic distortion of the waveform envelopes, resulting in the emergence of waveform extrema in the higher harmonics that are distinct from those of the conventional ACV theory of soluble redox couples. A quantitative connection is made between the peak potential of the second harmonic and the electrode reaction parameters. The analytic solutions agree well with measurements of the harmonic waveforms for metal electrodeposition in high temperature molten salts.
Electrolytic Extraction of Lanthanides (Ln=Tb, Dy, Ho) and Thermodynamic Evaluation of Cu-Ln Intermetallic Compounds in LiCl-KCl Melts
Authors: Li Mei , Han Wei , Sun Yang , Yang Xiaoguang
Published: May 2020

The electrochemical reductions of Ln (III) (Ln= Tb, Dy, Ho) were studied on W and Cu electrodes in LiCl-KCl melts by transient electrochemical methods. Compared with W electrode, the electrochemical results indicated a series of new reduction peaks appeared at less negative potential owing to the formation of different Cu-Ln intermetallics. Moreover, the thermodynamic properties of Cu-Ln intermetallic compounds were estimated by open circuit chronopotentiometry. Using linear polarization method, the exchange current densities (j
0) of Lns on Cu electrode were estimated, and the temperature dependence of j
0 was studied to estimate the activation energies. In addition, potentiostatic electrolysis was conducted to extract Lns on Cu electrode, and different Cu-Ln intermetallic compounds were identified by X-ray diffraction and scanning electron microscope and energy dispersive spectrometer. Meanwhile, the change of Ln (III) concentration was monitoring using inductively coupled plasma-atomic emission spectrometry, and the extraction efficiency was estimated.

Acknowledgement

The work was financially supported by the National Natural Science foundation of China (11675044, 21790373, 21876034 and 11875116), and the International Exchange Program of Harbin Engineering University for Innovation−oriented Talents Cultivation.
Electrochemical Copper Deposition on Nanoscale-Sculptured Aluminum for Mechanically Stable Joints with Optimal Electrical and Heat Transport Properties
Authors: Schmidt Catarina , Bahr Joerg , Obobi Kalu Chima , Carstensen Jürgen , Adelung Rainer
Published: May 2020

Copper is a material with a very high conductivity per volume; therefore it is widely used in the industry for nearly every electric application. However, with respect to weight aluminum (due to its low density of 2.7 g/cm3) shows a significantly higher electrical conductivity than copper. For many lightweight applications, aluminum would be the preferred material, but it lacks for good technical solutions for forming easy to apply, corrosion resistant, highly conductive contacts to (other) metals, especially to copper. Many of these problems are related to the native aluminum oxide coating on all aluminum surfaces in contact to air. State of the art solutions for electrical contacting aluminum surfaces require high temperatures and/or high pressure, thus making them expensive and typically damage the surface near microstructure of the aluminum.

In this abstract, we will discuss details of a room temperature technique, which allows for a mechanically stable, corrosion resistant, galvanic copper deposition on aluminum surfaces with extremely high interface conductivity for heat as well as for electrical current. This allows the application of standard bonding technologies for copper (e.g. soldering or using conductive glues) onto aluminum as a conducting material.

The copper deposition technique contains three steps:

1. A special surface preparation, i.e. nanoscale-sculpturing (cf. [1]) which creates a low corrosive aluminum surface structure full of mechanical hooks, composed of 100 crystallographic facets.

2. A preconditioning step before galvanostatic copper deposition.

3. Galvanic copper deposition controlling the nucleation of copper islands within the hooking structure and the morphology of the growing copper layer.

Due to the nanoscale-sculpturing, the deposited copper is mechanically stable bonded to the aluminum surface. Dependent on the demands for subsequent bonding applications, the galvanic copper deposition must be adjusted; e.g. for gluing, large parts of the hook like structure from the underlying aluminum surface should still exist after a thin layer of copper is deposited.

In contrast, for soldering application, a robust and thick layer of copper is needed.

How the nanoscale-sculpturing and the galvanic copper deposition can be adjusted to various application will be discussed in detail.

[1] Baytekin-Gerngross, M., Gerngross, M., Carstensen, J. and Adelung, R. (2016). Making metal surfaces strong, resistant, and multifunctional by nanoscale-sculpturing. Nanoscale Horizons, 1(6), pp.467-472.
Co-Reduction Behavior of Ce (III), Al (III) and Ga (III) on a W Electrode: An Exploration for Liquid Binary Al-Ga Cathode
Authors: Yang Dawei , Li Mei , Han Wei
Published: May 2020

It is well known that searching for electrode materials with high Ln/An separation efficiency in molten salt based electrorefining has been a big challenge. Both Al and Ga have exhibited excellent performance, respectively, for the Ln/An separation based on molten salt electrolysis. Therefore, in this work, the electrochemical behavior of Ce (III) on the binary Al-Ga alloy electrode was systematically explored by co-reduction of Ce (III), Al (III) and Ga (III) on a W electrode. The results showed that different kinds of alloys are formed on the surface of W electrode. In addition, several typical Ga-Ce and Al-Ga-Ce intermetallic compounds were obtained by potentiostatic electrolysis and the deposited products were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). It was found that ternary intermetallic compound Al2Ga2Ce and binary Ga2Ce and Ga6Ce were identified.

Acknowledgments

The work was financially supported by the National Natural Science foundation of China (11675044, 21790373, 21876034 and 11875116), and the International Exchange Program of Harbin Engineering University for Innovation−oriented Talents Cultivation.
Synthesis Method of Fe Metal Nanoparticles By Controlling the Metal Complex Condition in an Aqueous Solution and Its Application
Authors: Takahashi Hideyuki , Kijima Yu , Yokoyama Shun
Published: May 2020

It is well known that the melting point of metal element drastically change with decreasing the diameter of its particle into nano level, by obeying to the equation as follows,

Tnano = Tbulk (1-2s/(DH*R))

Here, Tnano is melting point of nanoparticles. Tbulk is melting point of bulk material, s is surface energy, DH is enthalpy change of melting, and R is radius.

Thus, the development of effective and green synthesis method of Fe nanoparticles means the development of new bonding method of Irons at low temperature, since Fe is most basic materials in resent world.

Fe nanoparticles were synthesized only in acidic solution by using strong reducing reagent, while it cannot be achieved in basic solution since iron hydroxide, which is easily formed in this condition, cannot be reduced into metals. However, former is not suitable for commercial synthesis method because of its intense reducing process. Thus, the reducing rout of Fe species under basic condition should be developed.

Here, until now, we tried to synthesized various metal/alloy nanoparticles, such as Pd20Te7 nanoparticles and uniform Cu-In (CI) alloy nanoparticles, by utilizing the restrict metallic complexes controlling method in an aqueous solution under room temperature. In this method, reduction potential of the metal species can be controlled under the room temperature, consequently metal/alloy nanomaterials with uniform and well crystallized structure can be successfully synthesized.

Therefore, in this study, aqueous phase synthesis method of Fe metal nanoparticles were developed.

To achieve the homogeneous reaction condition, metal complex species in the aqueous phase were restricted into single species by using calculation. Reduction potential of homogenized metal complex were analyzed by using cyclic voltammetry. Fe nanoparticles were synthesized by using chemical reduction method under ambient conditions using metal chlorides as metal sources and sodium borohydride as a reducing agent.

Calculation results indicated that Fe complex can be restricted into one species as the function of pH, complexing reagent species and/also concentration. For example, Fe complex can be restricted into Fe(NTA)2 only, in the case of 8<pH<11.

By using these homogeneous condition, metal Fe nanoparticles were successfully synthesized.

Other results, such as melting and/or bonding condition of synthesized materials, will present in our presentation. This work has been supported by the Grant-in-Aid for challenging Exploratory Research (19K22095).

[1] H. Takahashi et.,al, Applied Catalysis A: General 392 (2011) 80–85
Influence of an External Magnetic Field on the Morphology of a Ni-Co Alloy Obtained Electrochemically in a Deep Eutectic Solvent
Authors: Aldana-González Jorge , Hernández-Pérez David , Sánchez-Vite Enrique , Sánchez William , Montes de Oca Yemha María Guadalupe , Romero-Romo Mario Alberto , Arce-Estrada Elsa , Palomar-Pardavé Manuel
Published: May 2020

The electrochemical synthesis of Ni-Co metal particles formed from through electrodeposition of Ni2+ and Co2+ was carried out from a deep eutectic solvent of choline chloride and urea in 1:2 molar ratio at 70 °C, as electrolytic medium. From the application of a constant external magnetic field (1-5 µT), the morphology of the particles formed was studied. Additionally, the kinetic and thermodynamic parameters corresponding to the formation of the new phase on the surface of the glassy carbon electrode was determined, using physicomathematical models that involve bimetallic phases [1]. Figure 1(a) and (b), show the SEM images displaying a noticeable change in the morphology after applying 5 µT. Figure (c) and (d), correspond to the elementary analysis of figures (a) and (b), respectively.

Figure 1
The Electrochemical Reduction of Bauxite Residue Pellet in an Alkaline Aqueous Solution
Authors: Khalaghi Babak
Published: May 2020

Electrochemical reduction of pellets made from bauxite residue was carried out in 50 wt. % NaOH aqueous solution at 110 °C. The electrolysis was performed at a constant current equal to 300 mA.
Solution Chemistry of Alkaline Formaldehyde-Containing Electroless Copper Plating Systems and Kinetics of Electroless Copper Deposition
Authors: Norkus Eugenijus , Tamašauskaitė-Tamašiūnaitė Loreta
Published: May 2020

Electroless copper plating process using solutions containing formaldehyde as reducing agent is 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. Formation of mixed complex compounds between Cu(II) complexonates andK4Fe(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 are presented and the influence of the ligand nature on the process of electroless copper deposition is discussed.
Photoelectrochemical Oxidation of Organic Pollutants By TiO2 Based Nanostructured Catalysts
Authors: van der Zalm Joshua , Chen Aicheng
Published: May 2020

Advanced oxidative processes (AOPs) have been explored extensively for their application in waste water treatment and remediation. Their use of reactive oxygen species (ROS) to degrade organic pollutants that make their way into waterways shows promise for the complete removal of toxic materials. The implementation of electrocatalysts and photocatalysts as platforms the production of ROS allows for a green approach to AOPs, as it requires less additives for wastewater treatment and water purification. The use of catalysts for this process can often be economically unviable, as they commonly employ expensive noble-metals. To remedy this, the morphological and electrochemical character of more abundant materials, including metal-oxides such as TiO2, have been modified to increase their photocatalytic and electrocatalytic properties. In this presentation, we report on the development of nanostructured TiO2 catalysts for the photoelectrochemical degradation of atrazine, a common herbicide used in North America.

Nanoporous TiO2 was directly grown on a titanium substrate using an anodization process. Characterization of the TiO2 electrodes was carried out by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Electrochemical treatment of the nanoporous TiO2 was performed to further increase its catalytic activity towards the photoelectrochemical degradation of atrazine. The degradation process was monitored by UV-Vis spectroscopy, total organic carbon analysis and liquid chromatography-mass spectrometry. The effectiveness in the removal of Atrazine and the degradation mechanism will be discussed.
Electrochemical Disinfection of Biologically Treated Waste for Onsite Toilet Wastewater Treatment and Recycling: A Long Term Field Study
Authors: Varigala Siva Kumar , Hegarty-Craver Meghan , Cid Clement , Grego Sonia , Luettgen Michael
Published: May 2020

The Closed Loop Advanced Sanitation System (CLASS) was designed to treat, disinfect, and recycle toilet blackwater from existing flush toilets in a multi-story apartment building. CLASS used a combination of biological pretreatment and electrochemical oxidation processes. Two systems were tested in two unique sites in Coimbatore, India for over 7,500 treatment hours (combined) resulting in more than 180 m3 of blackwater treated to stringent quality requirements based on ISO 30500.1

Nutrients and organic load from the toilet blackwater were predominantly reduced aerobically and anaerobically using either a Sequencing Batch Reactor (SBR, Unit A) or an anaerobic-aerobic biodigester (Ecosan, Unit B). The electrochemical treatment provided for the disinfection of pathogens in the blackwater as well as further removal of remnant organic load and nitrogen (image attached). The water produced by the system nearly met ISO 30500 effluent standards and was reused for flushing by the residents of the apartment building for 89 days.

References:

1. International Organization for Standardization, Non-sewered sanitation systems — Prefabricated integrated treatment units — General safety and performance requirements for design and testing. 2018; Vol. 30500.

Figure 1
Development of Modified Surfaces of IrO2/Ta2O5¦¦Ti and RuO2/Ta2O5¦¦Ti By Electrophoresis to Develop Electrofarming of Cucumis sativus
Authors: Bustos Erika , Morales César , Solís Sara , Reyes María Yolanda , Bacame Francisco Javier , Manríquez Juan
Published: May 2020

The use of electrical energy has influence in the answer of biological systems called electrofarming, as different scientific reports have demonstrated applying a constant current or potential using almost a couple of electrodes (array 1D), where the germination of seeds and the increase of plants have been improved. For this reason, in our research group have studied the development of a protocol to increase the germination and growth rate of cucumber (Cucumis sativus) in Vertisol soil applying an electric field in presence of modified surfaces (IrO2/Ta2O5¦¦Ti). The electrofarming was developed using an array of 2D electrodes, maintaining the treatments in a growing chamber with artificial light, which has the appropriate conditions for getting the experiment without mitigating of the optimal development of the plants. According to the results obtained, it has the best time of emergency of seed and true sheep, increasing the height of plants and roots in the different sections of the electrochemical cell, in comparison with the results got in the plants that were not exposed to the electrofarming, where the edaphologic and microbiological properties have an important roll without variation of pH, an increase in the cationic exchange capacity, electrical conductivity and organic matter, with an electrophoresis phenomena, where Gram (-) bacteria and fungi went close to the anode (+) and the Gram (+) bacteria went close to the cathode (-) promoting the increase in the germination seeds and growing plants close to the anode (+) was the highest than close to the cathode (-).