bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Behaviour of Dissolved Iron Chloride in KCl+LiCl+NaCl Melt at 550ºC
Authors: Khalaghi Babak , Kvalheim Eirin , Tokushige Manabu , Teng Lidong , Seetharaman Seshadri , Haarberg Geir Martin 
Published: February 2020

Knowing the electrochemical behaviour of metallic ions in molten salts is crucial for electrometallurgical processes [1]. These processes include both extraction of metals from primary sources and recovery from wastes. Recently there has been a growing interest in developing an electrolytic process for iron production [2-3]. Furthermore, while an electrolytic process is used for treatment of wastes, iron is quite often present. Although, many studies have been done on iron in chloride melts [4-6], it seems little attention has been paid to FeCl3 behaviour and stability in these electrolytes.
In this study the electrochemical behaviour of iron in a salt bath composed of KCl+LiCl+NaCl was studied at 550°C by cyclic voltammetry and chronoamperometry. The working electrode was glassy carbon and iron was introduced to the melt by adding dehydrated FeCl3. Although FeCl3 is not fully stable in these types of solutions, both FeCl2 and FeCl3 showed to exist in the salt bath. Based on cyclic voltammograms the Fe (II)/Fe (0) electron exchange is a soluble/insoluble diffusion controlled process, although it cannot be considered fully reversible. The nucleation of metallic iron on glassy carbon electrode showed instantaneous characteristics. From the cyclic voltammetry results, the calculated value for Fe (II) diffusion coefficient is equal to 1.4×10-5 cm2 s-1. Although FeCl3 is not fully stable in these types of solutions, the Fe (II)/Fe (III) exchange reaction was observed at potentials near the chlorine evolution reaction. The oxidation of Fe (II) to Fe (III) is followed by a chemical reaction consuming the as generated FeCl3 ions. The equilibrium between FeCl3 and FeCl2 is also briefly discussed.
References:

D. Inman, S.H. White, The production of refractory metals by electrolysis of molten salts design factors and limitations, Journal of Applied Electrochemistry 8 (1978) 375.

G.M. Haarberg, E. Kvalheim, S. Rolseth, T. Murakami, S. Pietrzyk, S. Wang, Electrodeposition of Iron from Molten Mixed Chloride/Fluoride Electrolytes, ECS Transactions 35 (2007) 341.

D. Wang, A.J. Gmitter, D.R. Sadoway, Production of oxygen gas and liquid metal by electrochemical decomposition of molten iron oxide, Journal of the Electrochemical Society, 158 (2011) 51.

D. Inman, J.C. Legey, R. Spencer, A chronopotentiometric study of iron in LiCl-KCl, Journal of Applied Electrochemistry 8 (1978) 269.

Y. Castrillejo, A.M. Martínez, M. Vega, P. Sanchez Batanero, Electrochemical reduction of Fe(II) ions on different solid electrodes in fused ZnCl2-2NaCl mixture, Journal of Applied Electrochemistry 26 (1996) 1279.

A. Lugovskoy, M. Zinigrad, D. Aurbach, Z. Unger, Electrodeposition of iron(II) on platinum in chloride melts at 700–750°C, Electrochimica Acta 54 (2009) 1904.
The Utilization of Ionic Liquid Technology for the Degradation of Biopolymers
Authors: Reichert William Matthew , Goodie Taylor , Pischek Andrew M , Stenson Alexandra C. , Gayton Jacqueline 
Published: February 2020

Chitin, a polymer of N-acetyl-D-glucosamine, is the second most abundant in the world and makes up the exoskeleton of various arthropods and cell walls in various fungi. The structure of chitin makes it insoluble in common solvents and hinders development of applications of chitin. With the discovery that ionic liquids can dissolve chitin, the restrictions on the utilization of this unique biopolymer have been removed.
Like traditional salts, ionic liquids (ILs) are compounds composed entirely of ions. However, unlike traditional salts, ILs are composed of bulky ions, commonly large organic cations paired with either organic or inorganic anions. The size of the ions leads to a decreased melting point for the ILs, defining them as a compound composed entirely of ions with a melting point below 100°C. In addition to possessing lower melting points, ILs have demonstrated unique physical and chemical properties. Among these properties are a large liquid range, low vapor pressures, low flammability, and the ability to dissolve a variety of materials. These properties make ILs appealing to use in various chemical processes.
The unique property of ILs that is of interest to this research is their ability to dissolve various biopolymers, such as cellulose and chitin.1-4 The dissolution of these biopolymers has opened up new areas of research, including efficient degradation and processing the biopolymers for new materials. This study will investigate the effects of alkyl chain tether on catalyst behavior. This research will also observe the effects from varying the anion, temperature, and catalyst loading as well as utilizing minerals acids instead of IL catalysts.
(1) Qin, Y.; Lu, X.; Sun, N.; Rogers, R. D. Green Chemistry
2010, 12, 968.
(2) Xie, H.; Zhang, S.; Li, S. Green Chemistry
2006, 8, 630.
(3) Swatloski, R. P.; Rogers, R. D.; Holbrey, J. D. 2002, p 59.
(4) El Seoud, O. A.; Koschella, A.; Fidale, L. C.; Dorn, S.; Heinze, T. Biomacromolecules
2007, 8, 2629.
Electroreduction of Oxygen on Electrochemically Deposited Palladium-Gold Alloys on Glassy Carbon
Authors: Erikson Heiki , Sarapuu Ave , Kozlova Jekaterina , Matisen Leonard , Sammelselg Väino , Tammeveski Kaido 
Published: February 2020

In pursuit to find cheaper alternative catalyst material to replace platinum in low temperature fuel cells palladium has gained much attention due to the similar properties with Pt.1 Previously we have shown that electrodeposited palladium has higher electrocatalytic activity towards the oxygen reduction reaction (ORR) on gold substrate than on glassy carbon.2,3

The aim of this work was to study how gold supplement affects the ORR activity on electrodeposited palladium. In order to achieve this goal palladium and gold were co-deposited onto glassy carbon (GC) substrate at a constant potential. The precursor concentration ratio was varied in deposition solution to achieve different Au-Pd coatings. The surface morphology of Pd-Au alloys was studied with scanning electron microscopy and it was observed that the particle size does not change with changing palladium-to-gold ratio. Though there were some larger agglomerates but the average particle size was approximately 10 nm.
Electrochemical experiments were carried out in sulfuric acid and in potassium hydroxide solutions. From cyclic voltammograms the features of Pd and Au were observed.
The rotating disk electrode (RDE) method was employed for the oxygen reduction studies. In acid media the ORR activity depended strongly on palladium content and the half-wave potential of O2 reduction shifted positive with increasing Pd content in the deposition bath (Fig. 1a). The Tafel analysis was carried out which showed that the rate determining step is the sluggish transfer of first electron to O2 molecule (Fig. 1b). In alkaline media palladium and gold are both more active than in acid solution (Fig. 2a). The polarization curves of O2reduction for the Pd-Au coatings were similar whereas the ORR activity only slightly decreases with decreasing Pd content in the deposition bath. The Tafel behavior of ORR in alkaline solution is shown in Fig. 2b.
The RDE data were used to carry out the Koutecky-Levich analysis which showed that O2 reduction proceeds mainly through 4-electron pathway with some additional peroxide formation in sulfuric acid. The number of electrons transferred per O2 molecule (n) did not depend on potential for Pd-Au coatings, in contrast to bare gold electrode for which the value of n depends on potential.
In addition to the oxygen reduction studies, the process of hydrogen peroxide reduction in alkaline media has been also explored. The activity for peroxide reduction did not depend on the Pd content in the catalyst. The polarization curves were similar for all the Pd-Au coatings studied.
References
1. E. Antolini, Energy Environ. Sci., 2, 915, 2009.
2. H. Erikson, M. Liik, A. Sarapuu, M. Marandi, V. Sammelselg, and K. Tammeveski, J. Electroanal. Chem.,
691, 35, 2013.
3. H. Erikson, M. Liik, A. Sarapuu, J. Kozlova, V. Sammelselg, and K. Tammeveski, Electrochim. Acta,
88, 513, 2013.
Novel Non-Carbon Support Compositions and Architectures: Elaboration, Characterisation, Integration and Fuel Cell Testing
Authors: Jones Deborah J , Roziere Jacques , Cavaliere Sara , Subianto Surya 
Published: February 2020

One of the major issues concerning durability of PEMFC (Proton Exchange Membrane Fuel Cells) is the electrode degradation over time. Indeed, conventional electrocatalyst supports, based on carbon blacks, in fuel cell conditions suffer from corrosion leading to the aggregation, migration and detachment of the electrocatalyst nanoparticles with loss of performance. One strategy to overcome this issue is the replacement of carbon with more (electro)chemically stable supports. Recently, materials such as conducting oxides, nitrides and carbides have been shown promising applications as alternative supports. We are currently developing novel nanofibre and nanoparticle based PEMFC electrodes using non-conventional materials including niobium, tantalum and tungsten carbides, and doped titanium and tin oxides.
The challenges to be addressed are related to the development of nanofibres and nanoparticles having sufficient surface area to support and well disperse the electrocatalyst nanoparticles, while ensuring adequate electronic conductivity. We will review current progress in this area, and focus on morphology and physical-chemical properties of non-carbon supports prepared by electrospinning and hydrothermal methods, and the challenges of electrode development from them. Electrocatalytic activity of these systems will be addressed, in particular towards the oxygen reduction reaction, and the results of testing under accelerated ageing protocols will be described in order to compare their resistance to corrosion to that exhibited by conventional carbon based supports and assess their greater stability, and to underline the importance of a strong catalyst support interaction.
The Electro-Oxidation of H2, CO in a Model PEM Fuel Cell: Oscillations, Chaos, Pulses
Authors: Kirsch Sebastian , Hanke-Rauschenbach Richard , Sundmacher Kai 
Published: February 2020

H2, CO electro-oxidation in a model PEM Fuel Cell (PEMFC) is investigated at 37°C with the help of distributed current measurements. The main purpose of the experiments is to verify the formation of spatio-temporal patterns that have been predicted for a PEMFC with straight channels and a H2evolving cathode. For galvanostatic operation and a high feed flow rate well expressed globally coupled oscillations are found. For decreasing feed flow rate a period doubling bifurcation cascade appears. Potentiostatic control provokes the breakage of the strict phase relation between adjacent oscillators and the appearance of pulses as well as turbulence is seen. The turbulence is enhanced if an oxygen reducing cathode is introduced instead of a hydrogen evolving cathode. The findings are compared to existing predictions. The study of the patterns is of interest for PEMFC engineers as they directly determine the CO tolerance behavior of the PEMFC.
[1] R. Hanke-Rauschenbach et al. J. Electrochem. Soc. 157, B1521 (2010).
[2] S. Kirsch et al. J. Electrochem. Soc. 158, B44 (2011).
[3] S. Kirsch, et al. J. Electrochem. Soc. 160, F436 (2013).
Figure caption: Upper row - The segmented anode flow field with 80 segments per channel (channel length: 14.4 cm). The both inner channels are used for current distribution measurement, while the outer channels serve for homogenization. Each segment consists of two sub-segments that face across the channel. Lower row - As seen in the spatio-temporal plots of the measured current signal (corrected for its temporal space dependent average), the system behaves chaotically after a step into the voltage regime at which CO can be oxidized. In this potentiostatic experiment, the cathode was fed with air.
Electrochemical Micro-Oscillator Networks
Authors: Jia Yanxin , Kiss Istvan Z 
Published: February 2020

Stationary and oscillatory patterns can arise on the surface of a single electrode [1] and assemblies of discrete electrodes [2]. In traditional macrocells, the geometry of the arrangement of the cathode, anode, and the reference electrodes determines the strength and length-scale of the effective coupling that affects the features of the observed self-organized pattern formation.
To explore the temporal and spatial features of pattern formation in electrochemical devices with micro-electrodes, we have constructed epoxy-embedded electrodes with a poly-dimethyl siloxane (PDMS) flow cell. [3-4] It is shown that the microcell design typically used in electroanalytical chemistry produces large ohmic drops that can induce oscillations during the uniform corrosion of Ni electrodissolution.
Furthermore, the dynamical features of oscillatory Ni dissolution in sulfuric acid are investigated with 2-10 micro-electrode arrays. Equivalent circuit analysis is applied to formulate a theory for the electrical coupling strength between the electrodes as a function of the cell parameters: electrode surface area, length of the flow channel, and total cell resistance. The theory predicts a wide range of bidirectional positive, unidirectional negative, or unidirectional positive coupling depending on cell geometry. The predictions are tested in experiments with an on-chip integrated electrochemical cell that uses an epoxy-based substrate for 2-10 embedded metal wires with the PDMS fluidics. The network topology is extracted from the experiments with a phase model based coupling analysis. The results are discussed and design rules are formulated for tuning the dynamical characteristics of the chemical reaction system through intensifying or minimizing the coupling strength between the electrodes.
[1] K. Krischer, Principles of temporal and spatial pattern formation in electrochemical systems, in: B.E. Conway, O.M. Bockris, R.E. White (Eds.) Modern Aspects of Electrochemistry, vol. 32, Kluwer Academic, New York, 1999.
[2] I.Z. Kiss, T. Nagy, V. Gáspár, Dynamical Instabilities in Electrochemical Processes, in: V.V. Kharton (Ed.) Solid State Electrochemistry II, Wiley-VCH, Weinheim, 2011.
[3] I.Z. Kiss, N. Munjal, R.S. Martin, Electrochim. Acta, 55 (2009) 395-403.
[4] A.G. Cioffi, R.S. Martin, I.Z. Kiss, J. Electroanal. Chem., 659 (2011) 92-100.
Rotational Waves in Rings of Electrochemical Oscillators
Authors: Sebek Michael L , Kiss Istvan Z 
Published: February 2020

Chemical and biological systems exhibit network properties dependent upon the behavior of individual units and the interactions between units.[1] The presence or absence of interactions and the strength of the interactions determine the topology of the network and in turn the network properties. From a mathematical perspective, a variety of non-rotating and rotating waves can exist for a ring of locally coupled units[2] and the non-rotating solutions are the dominant outcome when coupling is the only mean of interactions regardless of the initial conditions.[3] Therefore, engineering is required to achieve solutions aside from the dominant non-rotating state.
The formation of waves is examined in oscillatory nickel dissolution where units of individual oscillators interact through external resistance which controls the strength of interaction. An experimental technique using a locally coupled twenty nickel electrode ring is presented in which through a combination of temporary alterations in topology and the application of global feedback provides all possible rotational solutions.
There are four rotational waves which can propagate about the ring and are distinguished by the velocity and the number of waves. The propagation rate is inversely proportional to the number of waves in the rotation (m) for all rotations. Solutions with no rotation have an m value of zero while rotational solutions are obtained for m=1,2,3,4. Larger m values (m ≥ 5) are shown to not be stable in the network. The results thus indicate that while network plasticity is thought to be significant in the operation of neural systems, it can also play a role in pattern selection of chemical systems.
References:
[1] J. L. Hudson, I. Z. Kiss, H. Kori, C. G. Rusin, Science 2007, 316, 1886-1889.
[2] G. B. Ermentrout, J. Math. Biol. 1985, 23, 55-74.
[3] D. A. Wiley, S. H. Strogatz, M. Girvan, Chaos 2006, 16, 1054-1500.
Perylenediimide-Graphene Donor-Acceptor Nanoensembles: Synthesis, Characterization and Photophysics
Authors: Karousis Nikolaos , Martin-Gomis Luis , Ohkubo Kei , Hasobe Taku , Sastre-Santos Angela , Fukuzumi S. , Tagmatarchis Nikos 
Published: February 2020

Graphene is an outstanding material, consisting of a two-dimensional (2D) single layer of sp2-hybridized carbon atoms bonded together in a hexagonal “honeycomb” lattice and presents remarkable electronic and mechanical properties, like quantum hall effect at room temperature, an ambipolar effect along with ballistic conduction of charge carriers, tunable bandgap and high elasticity.1 These exceptional properties of graphene make it an ideal candidate in construction of transparent conducting electrodes that could be used in energy conversion and storage systems. However, the preparation of high quality few-layered graphene materials is still an issue that must be circumvented and solvent assisted exfoliation using flat aromatic organic molecules as exfoliating assistants reveals as an extraordinary tool for that purpose.2

Herein, we present the liquid exfoliation of graphite to few layered graphene sheets together with the non-covalent supramolecular functionalization of exfoliated graphene sheets by the custom synthesized 1-N-methylpiperazinyl-N,N’-di(2-ethylhexyl)-perylene-3,4,9,10-tetracarboxydiimide (Pip-PDI).3 The planar aromatic Pip-PDI has the ability to non-covalently interact with exfoliated graphene sheets, stabilizing them and preventing their reassembly. On the other hand, the presence of the piperazine moiety on the bay position of the PDI core in the Pip-PDI makes it an ideal electron donor, nicely coupled with electron accepting exfoliated graphene, hence forming a novel donor-acceptor nanoensemble. The new PDI-graphene ensemble was characterized by complementary spectroscopic and microscopy techniques. Furthermore, electronic communication between the counterparts of the PDI-graphene nanoensemble was identified and probed by photophysical and redox assays, while prototype photoelectrochemical cells were constructed and evaluated.
Financial support from GSRT/NSRF 2007-2013 through action “ARISTEIA ΙΙ” project FUNGRAPH (3150) and CTQ2011-26455 and Prometeo 2012/010 is acknowledged.
References

A. K. Geim, K. S. Novoselov, Nat. Mater.
2007, 6, 183.

S. P. Economopoulos, N. Tagmatarchis, Chem. Eur. J. 2013, 19, 12930.

N. Karousis, L. Martin-Gomis, K. Ohkubo, T. Hasobe, A. Sastre-Santos, S. Fukuzumi, N. Tagmatarchis, Manuscript in preparation, 2014.
On-Chip Micro-supercapacitors Based on Nanoporous-Gold/ MnO2 Hybrid Electrodes
Authors: Zeng Zhigang , Zhou Haijun , Long Xiao , Hu Zhiyu 
Published: February 2020

Development of miniaturized electronics has stimulated demand for integration of energy storage units with electronic circuits. Micro-supercapacitors can be a promising strategy for future application in microelectric devices because of their properties of high power density, high-rate capability, long lifetime and high-frequency response. Progress in micro-fabrication technology has enabled on-chip micro-supercapacitors in an interdigitated planar form be compatible with integrated circuit. From a material perspective, nanostructured carbon-based materials are commonly used in electric double-layer micro-supercapacitors. In addition, transition metal oxides such as ruthenium oxide and manganese oxide, and some conducting polymers such as polypyrrole and polyaniline have been used as electrodes for pseudo-capacitive micro-supercapacitors.
MnO2-based pseudocapacitive electrodes have been considered as a promising candidate because of their high theoretical specific capacitance (1,370 F/g), environmentally friendly nature and low cost of raw materials. The main drawback of MnO2 is that the poor conductivity may limit the charge/discharge rate for high-power applications. However, Lang et al. have show that hybrid structures made of nanoporous gold and nanocrystalline MnO2 have enhanced conductivity, resulting in a specific capacitance close to the theoretical value (~1,145 F/g)[1]. The nanoporous gold not only plays a role as a double-layer capacitor, but also promotes electron transport through the MnO2 and benefits fast ion diffusion between the MnO2 and the electrolytes. Besides, the excellent mechanical properties enable nanoporous gold to be amenable to micro-fabrication processes[2]. The high specific capacitances and charge/discharge rates offered by such nanoporous gold/MnO2 hybrid structures make them promising candidates as electrodes in micro-supercapacitors.
Herein, we make our efforts in preparing high-performance nanoporous gold/MnO2 hybrid electrodes by electrodepositon method and fabricating micro-supercapacitors in interdigitated planar form. Our electrodeposited nanoporous gold/MnO2hybrid electrodes also have a specific capacitance close to the theoretical value (>1,000 F/g). The preparation and performance of hybrid electrodes and micro-supercapacitors will be presented.
1. Lang, X.Y., et al., . Nature Nanotechnology, 2011. 6(4): p. 232-236.
2. Jin, H.J. and J. Weissmüller, Science, 2011. 332: p. 1179-1182.