bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recovery and Electrowinning of Strategic Critical Materials from Molten Salts
Authors: Martinez Ana Maria 
Published: February 2020

Materials scarcity is a complex and global issue. The whole lifecycle of products has to be considered: form mining of materials to recycling of the products at the end of its life time.
Rare earth (RE) elements (lanthanides, yttrium and scandium) are often called "key enablers of green technologies", as they are vital in the development of e.g. hybrid electric vehicles, rechargeable batteries and wind power generators. In addition, RE elements are commonly used in our daily life: flat screens, mobile phones, tablets, economy bulbs, etc. Therefore, the RE metals (REM) have been identified as one of the most critical raw materials, as their forecast scarcity will have a detrimental impact on the economy, society, research and development areas.
Electrolysis from high temperature molten salts (chlorides and fluorides) is the main current industrial route for the production of "light" REM (those with lowest melting point, i.e. Ce, La, Nd, Pr, mischmetal) and their alloys with other transition elements. Today's electrolytic production of REM is mainly carried out in China, using the so-called "Chinese technology", which is rather primitive, little energy effective, and releases environmentally harmful by-products.
Moreover, it is clear that as the demand for raw materials increases, greater efforts will have to be made on recycling, since higher recycling rates will: i) reduce the pressure on demand for primary raw materials; ii) help to reuse valuable materials which would otherwise be wasted, and iii) reduce energy consumption, greenhouse gas emissions and other negative environmental impact from extraction and processing.
In the last years, SINTEF has been involved in investigations related to:

the improvement of the already existing industrial electrolytic processes for the production of REM and alloys, in terms of energy efficiency and reducing environmental impact.

the development of effective methods for the extraction of valuable REM from RE-containing wastes/scrap (secondary sources) based on electrolysis technologies.

An insight of the challenges associated to the forecast of RE shortage will be reported. The issues connected to today's electrolytic production of REM and the necessity of innovative extraction processes from end-of-life or scrap products will also be exposed. At the end, the research activities carried out in this field at SINTEF will be described and experimental results will be presented.
Materials for ORR Electrocatalysis: Catalytic Center and Substrate Effects
Authors: Luo Yun , Sreekuttan M. Unni , Mora-Hernandez Juan Manuel , Alonso-Vante Nicolas 
Published: February 2020

One of the most important challenges for polymer electrolyte membrane fuel cells (PEMFCs) in terms of facilitating its widespread commercial use is to improve the performance and durability of the electrocatalyst by developing novel catalysts (precious and non-precious catalytic centers) and support materials. One way to improve the oxygen reduction reaction (ORR) activity of Pt-based catalysts is to control Pt nanoparticles (Pt NPs) size, morphology and the dispersion onto substrates. Carbonyl chemical route for synthesizing Pt NPs facilitate a narrow particle size distributions (about 2-3 nm) [1], and homogeneous dispersion on different substrates [2,3]. A variety of carbon-based materials such as carbon nanotubes (CNT), graphite (HOPG), graphene, carbon nanohorns (CNH) and non-carbonaceous based materials, such as metal oxides (Titania, Yttria, Ceria, etc.,) [4,5] can be used as both catalyst and catalyst support materials. On the way to further explore the substrate effect on non-Pt electrocatalyst, CoSe2and CoO were supported on Carbon, CNH and nitrogen doped nanohorn (NCNH). The activity modulation in non-Pt catalysts was found to be strongly dependent on the morphology as well as the composition of substrate materials. The improved interaction of nitrogen species in NCNH and the metal centers modify the active reaction centers. This modified active reaction centers boost the catalytic activity with minimum overpotential for molecular oxygen reduction in alkaline medium (Figures 1a, b). Preliminary analysis indicates that this improved activity not only constrained in oxygen reduction but other catalytic reaction such as oxygen evolution reaction and hydrogen evolution reaction and further to an application on microfluidic fuel cells.
Acknowledgements
Authors acknowledge the partial support of the European Union’s Seventh Framework Programme (FP7/2007-2013) for the Fuel Cell and Hydrogen Joint Technology Initiative under grant agreement nr 303492 CathCat. SM U acknowledges the financial assistance through Raman-Charpak Fellowship, and JMMH acknowledges CONACyT fellowship.

[1] N. Alonso-Vante, Fuel Cell, 2006, 6, 182-189.
[2] J. Ma, A. S. Gago, W. Vogel, N. Alonso-Vante, Chemcatchem, 2013, 5, 701-705.
[3] L. Timperman, Y.J. Feng, W. Vogel, N. Alonso-Vante, Electrochimica Acta, 2010, 55, 7558-7563.
[4] Walter Vogel, Laure Timperman, Nicolas Alonso-Vante, Applied Catalysis A: General, 2010, 377, 167-173.
[5] C.Liu , Y.Wei and K.Wang, Chem.Comm., 2010, 46, 2483-2485.
Kinetics of Reaction with Oxygen of LnBa1-XSrxCo2-YFeyO6-δ (Ln - Selected Lanthanides) Oxides as Studied by Relaxation Methods
Authors: Swierczek Konrad , Zheng Kun , Klimkowicz Alicja 
Published: February 2020

Kinetics of the reaction with oxygen of the oxides, during changes of the oxygen partial pressure in the surrounding atmosphere, can be studied by various relaxation methods (e.g. mass or electrical conductivity relaxation). These methods allow to determine chemical diffusion coefficient (D) and surface exchange coefficient (K), related to the mentioned reaction [1, 2]. Theoretical basis of relaxation methods relies on the solution combining first and second Fick’s law and flux density at the surface boundaries. Depending on the geometry of the actual sample (3D, disc-like, etc.), the respective solutions are different, however, simultaneous and reliable determination of both coefficients requires additional conduction to be filled: 0.03 ≤ l·K/D ≤ 30 [3]. In real cases, this may limit range of temperatures and oxygen partial pressures, at which such determination is possible. Also, it suggests the importance of the dimensional parameter l.
In this work we present results concerning simultaneous determination of D and K, measured by mass and electrical conductivity relaxation techniques for perovskite-type oxides with LnBa1-xSrxCo2-yFeyO6-δ (Ln - selected lanthanides) chemical formula. The measurements were performed at elevated temperatures (600-800 ºC) in a wide range of oxygen partial pressures. The obtained results were analyzed taking into account crystal structure and the oxygen content in the considered compounds at high temperatures. It allowed to determine the correlation between structural (radius of Ln cation, degree of unit cell distortion, metal-oxygen-metal angle, unit cell free volume) and transport properties (oxygen diffusion coefficient, surface exchange coefficient, ionic and electronic component of the electrical conductivity) in the considered LnBa1-xSrxCo2-yFeyO6-δ.

Acknowledgements

The project was funded by the National Science Centre Poland (NCN) on the basis of the decision number DEC-2012/05/E/ST5/03772.

References

[1] G. Xiao, Q. Liu, F. Zhao, L. Zhang, C. Xia, F. Chen, J. Electrochem. Soc. 158 (2011) B455.
[2] J.A. Lane, J.A. Kilner, Solid State Ionics, 136-137 (2000) 997.
[3] M.W. den Otter, H.J.M. Bouwmeester, B.A. Boukamp, H. Verweij, J. Electrochem. Soc. 148 (2001) J1.
Fabrication and Characterization of Conductive Transparent Film Based on Carbon Nanotube for Optoelectronic Devices
Authors: Abdel-Fattah Tarek M , Dushatinski Thomas 
Published: February 2020

Optoelectronic devises are an integral part of our modern society. From the screens on our electronic computers to the solar panels that will hopefully replace fossil fuel sources, the need for theses devices and advancements for their sustainability and improved mass production is a large area of interest. A common component of all of these devices is a conductive and transparent cathode, usually transparent conducting oxides (TCOs). The downfall of TCOs is their degradation and incompatibility with progressive flexible substrates as their resistivity increases significantly with flexing and environmental exposure.
This study involved the fabrication and characterization of a multi-walled carbon nanotube (MWCNT) and sodium lauryl sulfate (SDS) composite deposited over polyethylene terephalate. The cathode materials have showndrastically effect of the performance of both organic and dye sensitized solar cells. The roughness of the films and electronic absorbance spectra are important as roughness increases the surface area over a two dimensional area and has shown to improve efficiency in solar cells. Also the absorbance spectrum of the film would need to be complementary to the photovoltaic material.

Figure 1: Electronic absorbance spectra of the MWCNT:SDS thin film that has been background corrected for PET.
Figure 1 shows the absorption spectra from both UV-Vis and IR ranges. The spectrum shows decreases in transmittance at 635 nm, 115 1nm, 1201 nm, 1223 nm, and 1630 nm. These absorbance peaks would not interfere with poly(3-hexylthiophene-2,5-diyl) (P3HT) that has a strong broad maxima at 525nm that extends between 400nm and 600nm [1]. The roughness (Ra) value of the MWCNT:SDS film is much greater at 21.8 nm as compared to 0.59 nm for unannealed ITO films [2].

References

Boland, P.; Sunkavalli, S.S.; Chennuri, S.; Foe, K.; Abdel-Fattah, T.M.; Namkoong, G. Inversigation of structural, optical, and electrical properties of regioregular poly(3-hexylthiophene)/fullerene blend nanocomposites for organic solar cells. 2010. Thin Solid Films. 518 1728-1731.

Raoufi, D.; Kiasatpour, A.; Fallah, H.R.; Rozatian, A.S.H. Surface characterization and microstructure of ITO thin films at different annealing temperatures. 2007. Appl. Surf. Sci. 253 9085-9090.
Controllable Phosphorus Doped Graphene Field Effect Transistor Using Phosphosilicate-Glass Films
Authors: Yoon Jin-sang 
Published: February 2020

Graphene consists of a single layer of sp2 hybridized carbon with atoms arranged in a honeycomb lattice. According to the valence and conduction bands touch at the Brillouin zone, graphene is a zero-band-gap semiconductor. To use graphene is semiconductor electronics, it is very important to open a band gap. Doping is an efficient way to tailor the electronics properties of pristine graphene. The dopant atoms can modify the electronic band structure of graphene, and open up a band gap. A few approaches have been developed recently for the doped graphene. Unfortunately, the previous methods are not controllable and simple to use in semiconductor business.
In this paper, Chemical n-type doping process of graphene using solid phase diffusion method of PSG (phosphosilicate glass) film is demonstrated. Figure 1 shows the doping process flow the graphene field effect transistor. PSG films were grown by CVD(Chemical vapor deposition) method on highly doped silicon wafer. In order to activate the dopants of the PSG films were annealed from 700°C to 900°C at intervals of 100(pre-annealing). The as-grown graphene layers were transferred on CVD grown 300 nm thick PSG film on heavily p-type Silicon substrate by a wet transfer technique. Dopants were diffused by annealing process to graphene on PSG films from 300°C to 500°C at intervals of 100°C. (post-annealing)
Both pristine and annealed graphene films were analyzed by raman and XPS(X-ray photoelectron spectroscopy). For electrical characterization, drain current-gate voltage(ID-VG) and drain–source voltage (VDS) bias of 1 V was applied to the FETs when measuring the ID–VG characteristic. Figure 2 shows the survey XPS spectrum of doped graphene samples. The atomic percentage of P in doped graphene increasing according to annealing temperature of the samples. According to these results, dopants were diffused on the surface of graphene. Figure 3 shows ID-VG characteristics of the FETs formed on the different graphene layers. Dirac point of the pristine graphene FET was observed at around +50 V since the pristine graphene generally serves as a p-type material in air because of unexpected impurity problems. However, Dirac points were respectively shifted from 21.5V to 0.5V after annealing treatment process, indicating that this n-type doping method using PSG annealed process successfully.
We developed graphene doping process with solid phase diffusion of PSG film which allows the control of Dirac point in graphene. The feasibility of the n-doping process for graphene-based electronic devices was successfully demonstrated in this paper by fabricating a MOS capacitor with n-channel FETs on annealed graphene. It is believed that can be expand the application, not only channel doping, but also reducing the contact resistance.
Study of Electrochemical Behavior of Hybrid Materials Based on GO/ PMo12/Conducting Polymer Obtained By Interfacial Polymerization
Authors: Baas-López José Martin , García- Chan Ceyli , Cuentas-Gallegos Ana Karina , Pacheco Daniella 
Published: February 2020

In the search to find materials with high conductivity, high electrochemical stability, recently the graphene family is presented as one promising advanced material. Nevertheless, are existing different challenges for avoid the restacks between their sheets and presented a semiconducting behavior due to their interaction with the medium, etc. Is for this what hybrids materials based on graphene could also offer great advantages for different applications for energy as for example electrochemical capacitors, solar cells, etc.
In this work was obtained hybrid materials based on GO/ PMo12/conducting polymer, conducting polymer/PMo12 andGO/ PMo12. The OG was obtained by Brodie method and thermally reduced. The method that was used for polymerization of monomers (pyrrole and aniline) was interfacial. For the cases of conductive polymer/PMo12, the ratio was 16.6% monomer and 83.4 % of PMo12 of weight while GO/ PMo12/conducting polymer this ration was of 10, 50 and 40% in weight, respectively.
All materials obtained were characterized by DRX, SEM, Raman and FTIR; and for evaluate their electrochemical behavior, the materials was deposited on cloth carbon and characterized by voltamperometry cyclic using a cell with three electrodes and H2SO4 1M at different scan rates; also was evaluated stability cyclic at 1000 cycles.
EIS Evaluation and Synthesis Nylon/Graphene Oxide Electrospun Composite Coating
Authors: Menchaca Carmina , García César , García Miguel Angel , Uruchurtu Jorge 
Published: February 2020

Graphene has attracted strong scientific and technological interest in recent years, and. It has shown great promise in many applications because of its unique physicochemical properties: high surface area (theoretically 2630 m2/g for single-layer graphene), excellent thermal and electric conductivity, and strong mechanical strength. Many methods have been developed to produce graphene. In general, nylon 6-6 has excellent mechanical resistance due to the mutual attraction of their long chains and their crosslinking. Since nylon discovery, a great interest has been developed due to its technological importance, its commercial characteristic, and its complexity related to the morphological changes associated to its crystallinity, not only in solid state, but also in solution and under melting point conditions.
A possible application for nylon 6-6/graphene oxide composite film is as a anticorrosion coating on the stainless steel bipolar plate for PEMFC due to the possible decrease of aggressive species diffusion through the coating as well as facilitating the electron discharge of the cathodic reaction, therefore diminishing the metal degradation and eliminating the passive layer that causes unacceptable reduction in contact resistance and possible fouling of the catalyst and the ionomer.
Starting from exfoliated graphite, different treatments were tested in order to obtain the best graphite oxide conditions. These included: calcination in a muffle for two hours at 700 or 800 °C. After that, ultrasonic agitation for three hours in acidic, basic or peroxide solutions was performed. Afterwards, particles were rinsed, filtered and dried at ambient temperature. These samples were characterized under SEM and FTIR techniques. Electrochemical cells were prepared using porous silica or nylon films as substrate covered with graphite oxide for further oxidation and reduction by electrochemical procedures. Polarization curves were performed to determine the best oxidation/reduction potentials under different acidic, alkaline and peroxide solutions. The best oxidation condition was obtained in KOH and the best reduction in H2SO4solutions. With these results potentiostatic oxidation and reduction curves were applied to further oxidize carbon species and then, reduced them onto the porous silica or nylon surface forming the graphite film.
Keywords: nylon, grapheme, electrochemical, synthesis.
Presenting author’s email: cesar.garcia@uaem.mx
Invited: Controlled Growth of Hierarchical Metal Oxide Nanoarchitectures by an Atmospheric Pressure Micro-Afterglow
Authors: Gries Thomas , Altaweel Ayman , Kuete Saa Duclair , Belmonte Thierry 
Published: February 2020

Metal oxide nanostructures with controlled shapes and size distribution have stimulated interest in fundamental scientific research owing to their morphology-dependent properties that offer potential wide-ranging applications. Plasma-assisted processing is one of the emerging processes used for the production of various metal oxide nanostructures [1]. In this study, we present an innovative strategy to synthesize different metal oxide nanostructures. This very simple process consists in exposing a metal surface directly to the afterglow of an argon-oxygen micro-plasma at atmospheric pressure [2].
Different metals are treated by the afterglow (Cu, Zn, Fe). For example in the case of copper, this flexible process makes it possible to design in a single treatment step, hierarchical nanostructures, which are not obtained by classical thermal oxidation like nanowalls or nanoflowers (figure 1). The growth mechanism is driven by stress-induced migration due to the development of stress gradients caused by the formation of copper oxide layers CuO and Cu2O. A specific study based on the local stress evolution measurement is proposed to determine accurately its influence on the growth of copper oxide nanostructures.
In this work, we present also the possibility to obtain the localized growth of ruthenium oxide nanostructures by applying the afterglow on a ruthenium substrate [3]. The mechanism is two-fold. First, a nanostructure made of lamellae covers the whole surface. Second, localized bunches of nanowires are distributed randomly, their growth being driven by the local stress that depends on the presence of emerging defects. We study also the influence of two alkali salts: NaCl and KCl. The presence of these crystals on the surface enhances the growth of nanowires all around them, created a circular area where nanowires are found (figure 2). The different existing growth models are considered to interpret these new results. This nanowire growth mechanism can be another important way to control the location of the metal oxide nanostructures.

Reference

[1] K. Ostrikov, U. Cvelbar, A. Murphy “Plasma nanoscience: setting directions, tackling grand challenges”, J. Phys. D: Appl. Phys. 44 (2011) 174001.
[2] G. Arnoult, R.P. Cardoso, T. Belmonte, G. Henrion “Flow transition in a small scale microwave plasma jet at atmospheric pressure”, Appl. Phys. Let. 93 (2008) 191507.
[3] D. Kuete Saa, R.P. Cardoso, F. Kosior, A. Altaweel, T. Gries, S. Laminsi, T. Belmonte “Growth of ruthenium dioxide nanostructures by micro-afterglow oxidation at atmospheric pressure”, Surf. & Coat. Technol. DOI: 10.1016/j.surfcoat.2013.10.040 (in press).
Invited: Scalable Production of Nanowire Arrays and Powders Using Plasmas
Authors: Sunkara Mahendra Kumar 
Published: February 2020

This presentation will highlight our group’s efforts with various scalable methods for continuous manufacturing of nanowires powders and arrays with help of plasmas. These scalable methods can be categorized in to the following: (a) scalable production of nanowires of low-melting metal oxide nanowire powders; (b) scalable production of nanowire arrays and powders for titania and related oxides; and (c) low-temperature growth of nanowires of silicon and related materials.

Scalable production method for nanowires of low-melting metal oxides: A novel atmospheric microwave plasma reactor is designed to process about a kilogram of nanowires per day and has already been demonstrated for the synthesis of tin oxide, zinc oxide and aluminum oxide nanowires.1 The resulting nanowires are 50-100 nm in diameter and several microns long.

Scalable production of titania and related metal oxide nanowires: We report a new ultrafast (reaction time on the scale of a minute) gas-phase method for synthesizing highly crystalline TiO2 nanowires (NWs) using direct oxidation of either Ti metal (foils or powders) or spherical TiO2 powders using an atmospheric pressure microwave plasma reactor.2 The current state of the art methods involve long reaction time scales (~1 day) for synthesis of TiO2 NWs.

Low-temperature synthesis of nanowire arrays of silicon and related materials: This presentation will also highlight our recent experiments on the synthesis of silicon nanowire arrays at temperatures lower than 300 C.
This presentation will also highlight our efforts in utilizing the nanowire based materials toward various energy conversion and storage applications including dye sensitized solar cells, lithium ion batteries, and photoelectrochemical water splitting.

References:

V. Kumar, J-H. Kim, C. Pendyala, B. Chernomordik, and M.K. Sunkara, “Gas-Phase, Bulk Production of Metal Oxide Nanowires and Nanoparticles Using a Microwave Plasma Jet Reactor”, J. Phys. Chem. C., 112, 46, 17750-17754 (2008).

V. Kumar, J-H. Kim, J.B. Jasinski, E.L. Clark, and M.K. Sunkara, “Alkali assisted, atmospheric plasma production titania nanowire powders and arrays”, Crystal Growth and Design, 11 (7), 2913 (2011).