bluuebunny/crossref_metadata_2025 huggingface dataset:
Nano Necklace Formed By Electroless Deposition of Metal on Polymer Nanofiber for Flexible Transparent Conducting Films
Authors: Shiratori Seimei , Takenaka Issei , Kyung Kyuhong , Bernasconi Roberto , Magagnin Luca
Published: February 2020

Flexible transparent thin films are strongly required for electronic devices, display or electric equipment.  To obtain both transparency and flexibility, electroless deposition on the polymer nanofiber was carried out. As the result, we successfully obtained uniformly metalized nanofiber with 300nm in diameter by all wet process without using any vacuum process.

 First, we fabricated Nylon 6 nanofiber with nanoweb structure with 50nm in diameter by electrospinning method1. Then, NiP was metalized by electroless deposition on the nylon 6 nanofiber at the relatively lower temperature of 60 to 65 oC for 40 seconds2. By the Scanning Electron Microscope observation, it was found that numerous spherical shape of NiP beeds with the diameter of 300nm were tightly connected and arranged on the surface of nylon 6 nanofiber with the diameter of 50nm. It seems that same size of numerous metal beeds were formed just like “Nano Necklace” surrounding the nylon 6 nanofiber.

  The electrical characteristics and the mechanical characteristics were evaluated and the possibility of the future application for the flexible transparent conductive electrodes were suggested.

References:

1)Ding, B., Li, C., Miyauchi, Y., Kuwaki, O., Shiratori, S. Nanotechnology, 2006, 17, 3685-3691.

2)Magagnin, L; Sirtori, V; Seregni, S; et al, Electrochimica Acta, 2005,50,23,4621-4625.

Fig.  “Nano Necklace” formed by Electroless Deposition of NiP on the surface of Nylon 6 nanofiber

Figure 1
Control of the Magnetism of Iron Oxide Nanoparticles By Growth Parameters within Nanostructured Silicon
Authors: Granitzer Petra , Rumpf Klemens , Poelt Peter , Reissner Michael
Published: February 2020

In the frame of this work nanostructured silicon is used as template for the deposition of iron oxide within the pores. The aim is to fabricate a nanocomposite which is appropriate to be used as vehicle for magnetic field guided drug delivery. For this reason several preconditions have to be fulfilled, e.g. no magnetic remanence at room temperature and biocompatibility of the used materials. The latter one has been evidenced by different authors before (1, 2, 3). Concerning the adjustability of the magnetic properties of the system the filling of the porous silicon with iron oxide nanoparticles has been elucidated in detail and the growth of the iron oxide structures within the pores has been investigated. The growth mechanism strongly depends on the electrolyte composition as well as on the applied potentiostatic conditions. The magnetic properties, especially the transition temperature between superparamagnetic behavior and blocked state (TB) of the nanocomposite can be controlled by the filling procedure. TB shifts to higher temperatures with increasing magnetic coupling between the particles. Dependent on the packing density as well as on the size of the particles within the pores the magnetic interactions can be modified and thus the blocking temperature can be tuned. These investigations have been carried out for particle sizes between 4 nm and 12 nm. An optimization of the magnetization (high filling density as possible) and its correlation with the blocking temperature has been carried out. An assessment of the iron oxide deposition dependent on the template and the chemical parameters as well as of the magnetic properties in dependence on the particle size, inter-particle distance and template morphology of the nanocomposite will be presented.  

1. D. Ling, T. Hyeon, Small, (2012) DOI: 10.1002/smll.201202111.

2. J. Coffer, M.A. Whitehead, D. Nagesha, P. Mukherjee, G. Akkaraju, M. Totolici, R. Saffie, L. Canham. Phys. Stat. Sol (a), 202, 1451 (2005).

3. P. Granitzer, K. Rumpf, Y. Tian, G. Akkaraju, J. Coffer, P. Poelt, M. Reissner, Appl. Phys. Lett. 102, 193110 (2013).
Platinum Monolayer Perfection with the Assistance of Citric Acid in Galvanic Displacement Reaction
Authors: Shao Minhua , Brankovic Stanko R
Published: February 2020

The slow kinetics of oxygen reduction reaction (ORR) is one of the main obstacles hindering the commercialization of low-temperature fuel cells.1 Core-shell catalysts consisting of a Pd-based core and a Pt shell (Pt/Pd/C) showed higher Pt mass activity than commercial Pt/C catalysts due to a synergistic effect between the core and Pt shell and substantially complete utilization of Pt atoms.2 The synthesis of a core-shell catalyst involves two main steps: (1) underpotential deposition (UPD) of a Cu monolayer on the surface of Pd nanoparticles; (2) displacement of the Cu atoms with Pt via a simple oxidation-reduction reaction: Cu + Pt2+ → Pt + Cu2+.  The challenges associated with production of core-shell catalysts in a large scale are the uniform deposition of a Pt overlayer on the Pd core during the displacement of Cu atoms.

Herein, we report our study on the production of core-shell catalysts at the gram scale by introducing citric acid in the Pt-Cu displacement reaction solution. It was found that the quality of the Pt monolayer shell could be significantly improved by adding citric acid.3,4 In the presentation, we will discuss the role of citric acid in smoothing the Pt overlayer based on the experimental and density functional theory calculation results. The characterization and evaluation results of core-shell structures will be shown as well.

References

1. Electrocatalysis in Fuel Cells: A Non- and Low- Platinum Approach; Shao, M., Ed.; Springer: London, 2013.

2. Adzic, R. R.; Zhang, J.; Sasaki, K.; Vukmirovic, M. B.; Shao, M.; Wang, J. X.; Nilekar, A. U.; Mavrikakis, M.; Valerio, J. A.; Uribe, F. Topics in Catalysis
2007, 46, (3-4), 249-262.

3. Humbert, M.; Smith, B.; Wang, Q.; Ehrlich, S.; Shao, M., Electrocatalysis 2012, 3 (3-4), 29.

4. Shao, M. H., et al. Phys. Chem. Chem. Phys. 2013, 15, 15078
Progress in Pulse Plating Atomic Layer Deposition (PP-ALD)
Authors: Stickney John Lewellen , Czerniawski Justing , Bui Nhi , Zhang Xiaoyue , Shen Sheng
Published: February 2020

A family of absorber materials of interest for high volume production of photovoltaics is referred to as CZTS, or Cu2ZnSn(S,Se)4.  The primary advantages of these materials are that they are made from nontoxic earth abundant elements.   This group has been working on electrochemical atomic layer deposition (E-ALD) as a method for the formation of PV absorber materials for many years.  E-ALD involves the use of surface limited reactions to form deposits an atomic layer at a time, in order to achieve atomic layer control during the growth process. E-ALD has been based on the alternating of precursor solutions of the desired elements and the use of UPD to limit growth to an atomic layer at a time.   The E-ALD method has important advantages for the formation of nanofilms of materials, including: conformal growth, atomic layer control over deposition, room temperature deposition, and scalable principles.  There are a range of new PV designs involving nanostructured electrodes and plasmonic layers where the absorber layer thickness can be considerably thinner than the 4 µm used for say the formation of CdTe based thin layer photovoltaics.  However, even a µm of CdTe formed using present E-ALD technology would take at least 100 time longer then the presently used industrial methods.  Present E-ALD technology is can be used to grow films from a nm up, but is most applicable to where conformal, high quality nanofilms are needed.   The rate of growth using E-ALD is presently limited by the time it takes to change solutions, and the solution should be changed at least twice per atomic layer.   The present report involves efforts by this group to develop of a variant of E-ALD based on changing the potential, pulsing, rather than solution exchanges, greatly decreases the cycle time.   Presently, the Authors referred to it as potential pulse ALD (PP-ALD).   Preliminary results on the formation of Cu2Se, ZnS, and other possible binary compounds which could serve as components of a CZTS absorber layer will be discussed.
Electrochemical Oxidation of Lignin to Value-Added Chemicals
Authors: Arroyo-Torres Christian , Movil-Cabrera Omar , Staser John A
Published: February 2020

Lignin represents a significant waste in pulping mill streams, and is generally burned during the chemical recovery process to generate heat.  However, its high heating value results in a bottleneck on the pulping process, and as the only renewable raw material for aromatic compounds, it is woefully underutilized as a heat source.  Our work focuses on electrochemical oxidation of lignin-rich streams to generate value-added chemicals of industrial relevance.  We have begun to investigate the mechanism of lignin oxidation, in which several proceeding chemical or electrochemical reactions are possible that influence the product distribution and depend on oxidation conditions.  Because lignin is soluble in alkaline solutions, we are able to oxidize lignin on inexpensive, nonprecious metal electrodes.  We will present voltammetric data that show the potentials at which lignin oxidizes, and will show GC/MS results that identify lignin oxidation products as a function of oxidation conditions (i.e., potential and time).  We will present our work in elucidating the mechanism that lignin undergoes during electrochemical oxidation, with an eye toward controlling the oxidation products.
Electrochemical Separation and Purification of Astatine for Radiopharmaceutical Application
Authors: Ganesan Selvarani , O'Hara Matthew J
Published: February 2020

The second longest lived isotope Astatine (211At: T1/2=7.5 h), is one the most promising α-emitters for targeted cancer radiotherapy. The liquid/liquid extraction method has been shown to provide good separation of 211At from bismuth metal.  However, of the liquid/liquid (L/L) extraction (separation) steps [1] used in the current manual isolation procedure presents a significant challenge due to the nature of the diisopropyl ether / hydrochloric acid (DIPE/HCl) and diisopropyl ether / sodium hydroxide (DIPE/NaOH) mixtures.  The present work is focused on to evaluate the feasibility of electrochemical methods in the purification of 211At.  This approach will be an alternative to hydrogen astatide (H211At) wet distillation.

 At the present time, Bi (III) is considered the primary contaminant from which 211At must be electrochemically purified.  The initial electrochemical studies were conducted with iodine as an astatine segregate in bismuth solution. As the concentration of astatine in the original solution is much lower than micro molar levels, there are two different approaches have been adopted; (i) separation of bismuth from the original solution [Ref 1; step 4] through electrodeposition and (ii) direct extraction of iodine from the original solution [Ref 1; step 3 or 4]. Figure 1(a) shows the cyclic voltammograms (CV) for bismuth on various substrate electrodes; namely Pt, Au and glassy carbon (GC). In these, the GC substrate found to be the suitable martial than others, which could be due to surface nature of carbon. In the case second approach, initially, iodide separation was carried out without bismuth in an acidic electrolyte with various concentrations of iodide to identify the suitable substrate material and minimum separation levels. Figure 1(b) shows the model CV for iodide on Pt electrode, surprisingly iodine deposit was also observed at the working electrode. Conversely, there are no characteristic electrochemical peaks and deposits were observed for GC and Au. This study indicates iodide can be extracted with Pt electrodes and Pt catalyzes the reactions.

Acknowledgements

Financial support from the Department of Energy (DOE) is greatly acknowledged.  Selvarani Ganesan is thankful for subcontract from the Pacific Northwest National Laboratory (Contract No. 244236; PI: Matthew J O'Hara).

Reference

E.R. Balkin, D.K. Hamlin, K. Gagnon, M.-K Chyan, S. Pal, S. Watanabe, and  D.S. Wilbur, Appl. Sci., 3 (2013) 636-655.

Figure 1
Electrophoretic Mobility and Deposition in High Pressure High Temperature Boiler Environments
Authors: Raman Balaji , Hall Derek M. , Shulder Stephen J , Lvov Serguei N.
Published: February 2020

Suspended magnetite [Iron (II,III) Oxide] particles in boiler water deposit on the walls and orifice plates in boilers, impeding flow and causing inefficiencies. Operating data suggests that reducing conditions and boiler water chemistries in the boiler enhances development of magnetite deposits. The inter particle interaction due to the zeta potential developed on the colloidal magnetite particles could also be a factor in deposition. In order to study the mechanism behind the deposition of suspended magnetite on stainless steel a high temperature high pressure electrophoretic deposition cell has been developed. An autoclave pressure vessel with graphite O-ring gaskets is serve as the electrophoretic deposition cell simulating the boiler conditions (300 °C and 9 MPa). Carefully prepared test solution imitating boiler water chemistries containing suspended magnetite particles are pumped in to the autoclave. The test solution is prepared in an anaerobic environment to prevent oxygen contamination. The tests  simulate the boiler conditions in terms of temperature, pressure and boiler water chemistry. The experimental setup has been designed to allow the sampling of test solution to monitor the pH, dissolved oxygen level and solution potential. 304 Stainless Steel samples were placed in the autoclave to serve as the substrate for deposition. A three-electrode assembly, consisting of 304 SS substrate (working electrode), a counter electrode and a quasi-reference electrode, has been used to characterize the deposition process using in-situ Electrochemical Impedance Spectroscopy measurements. The goal is to understand the influence of boiler water chemistries on the surface charge properties of the suspension. The surface properties can be related to the stability of suspended matter, which in turn relates to the deposition of particles on the substrate. The growth of the deposits is characterized using in-situ Electrochemical Impedance Spectroscopy measurements. Post-test analysis of the steel sample was carried out using Scanning Electron Microscopy (SEM) techniques. Preliminary tests have been carried out with a test solution pH of about 9.4, controlled by adding NH4OH (All Volatile Treatment). Deposition was observed on all samples from all the tests. In-situ EIS measurements have been recorded at test conditions of 300 °C and 9 MPa over the duration of the test. The results will be significant in understanding the inter-particle interactions and electrophoretic deposition at high temperature-high pressure conditions.
Cu Electro-Redox on the Surface of Single-Walled Carbon Nanotube Network
Authors: Ou Zhiyuan , Li Jinhui
Published: February 2020

In this study, pristine single-walled carbon nanotube (SWNT) networks were used as the templates for the copper nanoparticle electrodeposition and the electro-redox process were investigated. The working electrode, SWNT networks, was prepared via catalyzed chemical vapor deposition on insulating SiO2 surface and was characterized by scanning electron microscopy, thermogravimetric analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, and linear sweep analysis. In the static experiment (batch reactor), deposition of high-density Cu nanoparticles on the SWNTs was observed via atomic force microscopy and field emission scanning electron microscopy, over extensive periods (45s), with contiguous formation from the boundary to further distances. Mass transfer was quantitatively analyzed via chronoamperometry and normal pulse voltammetry and physical adsorption of the copper ions were observed to demonstrate a positive temperature-dependence. A range of Cu ion concentrations was used to analyzed the electron transfer till the mass transfer and adsorption processed were saturated and the electron transfer rates were determined to be 1.5×1017 and 2.6×1018e-s-1m-2 at anode potentials of 0.3 and 0.5V,repectively. All these above approaches described the nucleation and growth processes of Cu nanoparticles on SWNTs during electrodeposition. In comparison with Ag and Pt growth reported before, Cu nanoparticles grew less rapidly and progressively. The dynamic experiment (filter reactor) is on-going based on results of the static one. Our work is promising to provide a new route to recover copper from waste mining water.
(Invited) Structure Measurements for Organic Photovoltaics Manufacturing
Authors: DeLongchamp Dean M
Published: February 2020

Organic photovoltaics (OPV) is a promising candidate technology for the low-cost fabrication of modules to harvest solar energy.  Although OPV technology has significantly matured over the past few years, there remain significant challenges in addressing the gap between lab-scale devices and real manufacturing. Structure-property-performance relationships for OPV devices are still underdeveloped, and relationships based on one system are not necessarily transferrable to new, higher-performance systems. This talk will describe our efforts to develop measurements that support OPV manufacturing. Using a blade coating process as a prototype for slot-die coating, we have developed several techniques to observe the structure of OPV films in-situ as they dry. Our measurements include synchrotron-based X-ray scattering and a variety of optical methods. We use these techniques to identify the mechanisms by which formulation and processing choices influence the nanoscale structure of the films. Several OPV systems will be described including polymer/fullerene, small-molecule/fullerene, and polymer/polymer. Throughout solidification, we can follow the number of phases, their composition, and the extent of order within them. In-situ techniques provide far more information about the solidification process than can be obtained by measuring already-dried films, providing a valuable tool to guide the selection of formulation and processing parameters.
(Invited) Ultrafast Infrared Spectroscopy of Charge Generation in Organic Photovoltaic Materials
Authors: Asbury John B.
Published: February 2020

Ultrafast infrared spectroscopy is used to examine the mechanism of charge generation in organic photovoltaic materials.  We examine archetypal classes of electron acceptors in organic photovoltaic (OPV) materials and reveal how their molecular structures determine whether hot CT state dissociation can influence the dynamics and yield of photo-generated electrons and holes.  Furthermore, we tune the degree of aggregation and therefore charge carrier delocalization in OPV materials and elucidate the corresponding influence on the yield of photogenerated charge carriers.  The data suggest that a distribution of local molecular environments exist at donor/acceptor interfaces.  Some of these are able to support greater degrees of charge delocalization and therefore more efficient dissociation CT states into independent charge carriers.  Molecular structure and domain composition influence the density of interfacial sites capable of separating charge, which determines the overall quantum yield for charge generation of a given OPV material.
(Invited) Spectroscopic Investigations of Stable Nitroxyl Radical-Containing Polymers
Authors: Ferguson Andrew , Hughes Barbara Katherine , Braunecker Wade A. , Bobela David C. , Gennett Thomas
Published: February 2020

Stable nitroxide radical bearing organic polymer materials are attracting much attention for their application as next generation energy storage materials. A greater understanding of the inherent charge transfer mechanisms in such systems will ultimately be paramount to further advancements in the understanding of both intrafilm and interfacial ion- and electron-transfer reactions. This work is focused on advancing the fundamental understanding of these dynamic charge transfer properties by exploiting the fact that these species are efficient fluorescence quenchers. We systematically incorporated fluorescent perylene dyes into solutions containing the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) radical and controlled their interaction by binding the TEMPO moiety into macromolecules with varying morphologies (e.g., chain length, density of radical pendant groups). In the case of the model compound, 4-oxo-TEMPO, quenching of the perylene excited state was found to be dominated by a dynamic (collisional) process, with a contribution from an apparent static process that is described by an ∼2 nm quenching sphere of action. When we incorporated the TEMPO unit into a macromolecule, the quenching behavior was altered significantly. The results can be described by using two models: (A) a collisional quenching process that becomes less efficient, presumably due to a reduction in the diffusion constant of the quenching entity, with a quenching sphere of action similar to 4-oxo-TEMPO or (B) a collisional quenching process that becomes more efficient as the radius of interaction grows larger with increasing oligomer length. This is the first study that definitively illustrates that fluorophore quenching by a polymer system cannot be explained using merely a classical Stern-Volmer approach but rather necessitates a more complex model. We extend this to a spectroelectrochemical study of their redox reactions in solution and cast as thin films on conducting substrates, and utilize these measurements to probe electron transfer to and/or from the nitroxyl radical-containing polymers.
(Invited) Development of Printed Flexible Organic Solar Panels, Field Effect Transistors, and Logic Circuits on PET Substrates
Authors: Alem Salima , Chu Ta-Ya , Lu Jianping , Kololuoma Terho , Tao Ye
Published: February 2020

In this talk, I will introduce the research activities on the development of printed flexible organic solar panels, field effect transistors, and pMOS based logic circuits under NRC’s Printable Electronics Flagship Program.

I will report the development of polycarbazole-based, printed organic solar panels and the application of a printable, air-stable, and annealing-free zinc oxide nanoparticle (ZnO NP) solution in the fabrication of inverted bulk heterojunction solar cells. The as-coated ZnO thin films are insoluble in organic solvents and can be directly used as an electron extraction layer in solar cells. The process is R2R compatible. Our non-encapsulated inverted solar cells are highly stable with their PCEs remaining unchanged after being stored in air for more than 50 days.

The development of inkjet-printed pMOS inverters and logic gates on flexible substrates will be also presented. The fabrication of inkjet-printed OTFTs has achieved a yield of 97%. Different types of logic gates, inverters, and ring oscillators have been successfully fabricated by using these basic pMOS devices.
(Invited) Chemical Stability and Electronic Behavior of Atomic Layer Deposited Metal Oxide Thin Films
Authors: Strandwitz Nicholas C , Bao Bo , Correa Gabriela Calinao
Published: February 2020

Modification of semiconductor surfaces via the growth of metal oxide overlayers, particularly by atomic layer deposition (ALD), has become a topic of recent interest for surface passivation and chemical protection in semiconductor/liquid junctions.  For example, in photoelectrochemical water splitting, semiconductor surfaces typically must be protected with insulating or conducting layers that are stable in the electrochemical environment.  Further, ALD thin films have been used as overlayers in a variety of other environments including those relevant to batteries, corrosion protection of metals, and for water diffusion barriers.  Although thermodynamic stability of a solid phase in various environments can be readily assessed, more complex phenomena such as film hydration and dynamic dissolution/precipitation can occur, dramatically impacting the efficacy of thin protective ALD films. 

            Motivated by this widespread interest in ALD protective layers, we have examined the chemical stability of the two of the most common ALD materials, alumina and titania, in a variety of environments.  Films were deposited using thermal ALD using trimethylaluminum and tetrakis dimethylamido titanium for alumina and titania, respectively.  Film thickness was then monitored after immersion in various liquid media, which included acidic, neutral and basic aqueous solutions and mercury.  Surface morphology was investigated using atomic force microscopy.  Our results indicate a drastic increase in stability of the ALD films after post-deposition thermal treatment. Further, for alumina films in pure water, a dramatic restructuring occurs changing film density, thickness, and morphology.  Mercury contacts induce a slow increase in film thickness that is attributed to mercury oxide deposition.  Finally, we report how the effective surface recombination velocities at these interfaces evolve over the course of thermal annealing and various solution treatments.  These results provide important guidelines for the applicability of ALD oxides as protective/passivating films on semiconductor electrodes for applications in sensing and photoelectrochemical water splitting.
(Invited) Stabilizing Semiconductor-Solution Interfaces Via Chemically Stable but Electronically Defective Coatings
Authors: Hu Shu , Shaner Matthew , Lichterman Michael Frankston , Richter Matthias Hermann , Verlage Erik , Mayer Thomas , Brunschwig Bruce , Dapkus Paul Daniel , Lewis Nathan S.
Published: February 2020

Recently, a photoelectrode protection strategy, which uses an amorphous “leaky” TiO2 coating to form a complex semiconductor/TiO2/Ni structure, has shown to stabilize semiconductor-solution interfaces against photoanodic corrosion.  Particularly, stabilizing semiconductor-aqueous solution interfaces for water oxidation is important because water oxidation is required for all solar fuel strategies, e.g. H2 production and CO2 reduction.  We show that this TiO2protection strategy has stabilized a number of 1.1 – 1.9 eV band gap light absorbers including Si, group III-V, group II-VI semiconductors, their tandem structures and wire structures for up to 2000 hours continuous water oxidation in 1 M KOH(aq).  Because of this, various otherwise unstable materials can be brought back to the table again for building photoelectrochemical devices.  A water splitting reactor prototype of ~10% solar-to-hydrogen efficiency was also built.    

The n-doped Si/TiO2/Ni structure also operates as a high barrier height junction for solar energy conversion.  To further understand the mechanism of “leaky” TiO2 protection and the role of Ni electrocatalyst overlayers, we used Si/TiO2/Ni structures as a model system to study solid-solution interfaces.  TiO2 coatings of 3 – 143 nm in thickness introduce two interfaces: a TiO2/liquid interface and a TiO2/n-Si heterojunction.  We have employed operando ambient-pressure X-Ray photoelectron spectroscopy (AP-XPS) to study TiO2/Ni/liquid and TiO2/liquid interfaces, and directly observed their ohmic and rectifying junction behavior, respectively.  We also extensively investigated n-Si/TiO2 heterojunction interfaces by employing photoelectrochemical, solid-state electrical, and photoelectron spectroscopic techniques.  The distinctive electrical behavior of n-Si/TiO2 heterojunctions will be compared with conventional semiconductor/metal and semiconductor/liquid junctions.  Because electronic defect states exist in band gaps of “leaky” TiO2, their effects on the formation of n-Si/“leaky”TiO2 heterojunctions will be discussed.  This interfacial study reveal several strategies for improving the performance of thin-layer protected photoelectrodes as well as for further expanding selection of “leaky” protective coatings.
Synthesis of Metal Oxides/Graphene Nanocomposites for Applications in Lithium-Ion Battery
Authors: Nan Jiaqi , Dong Hongzhou , Li Guicun , Yu Liyan , Qin Yong , Dong Lifeng
Published: February 2020

Over the past few years, lithium-ion battery has become a research spot due to its high voltage, high energy density and long cycle life. Traditional lithium-ion batteries employed graphite as anode material. However, graphite suffers from several shortcomings, such as low specific capacity, sluggish discharge current density, and relatively low cycle life. The discovery of graphene makes it possible to improve the performance of lithium-ion batteries significantly. Graphene with excellent electrochemical performance has attracted more and more attention. Graphene is a single layer of honeycomb sp2-hybridized carbon atoms with large surface area, high electrical conductivity and high thermal conductivity.

In this report, we employed graphene and graphene-based composite material as anode materials for lithium-ion battery to improve their performance. Stannic oxide (SnO2), cobalt oxide (Co3O4), and vanadium pentoxide (V2O5) were synthesized respectively on graphene surfaces. The incorporation of metal oxides can further improve electron mobility of graphene and lithium-ion battery charge/ discharge stability. The performance of lithium-ion batteries was tested by charge-discharge experiments, and their charge-discharge current density, charge-discharge voltages, charging rate, and cycle stability were measured and discussed.
A P-GaInP2 Photoelectrode for Water Reduction Stabilized with TiO2 and MoS2 Catalyst
Authors: Gu Jing , Young James L , Neale Nathan , Turner John A
Published: February 2020

To achieve an efficient, low cost system for the conversion and storage of solar energy, stable light absorber and robust electrocatalyst need to be coupled into one setup. Noble metals like platinum are usually used because of their high efficiency. Identifying earth-abundant material alternatives to replace precious metal catalyst is highly desired. One of the most efficient PEC systems demonstrated to date is the III-V PEC/PV tandem concept pioneered at NREL however it suffers from inert instability under aqueous solution. Here, we report studies of a p-GaInP2 photocathode protected via an atomic layer deposition of TiO2. With an appropriate TiO2 layer thickness as well as HER catalyst (MoS2) electrodeposited to the TiO2 surface, the resulting photoelectrode mediates photo-driven H2 production with a current density of ~10 mA∙cm-2 at a potential of 0 V vs. RHE under 1 sun illumination either at neutral or acidic solution. The MoS2 modified GaInP2 also showed comparable performance as GaInP2-Pt control whereas the bare surface demonstrate only half or less photocurrent density at the same condition.
(Invited) Direct Electrodeposition of Crystalline III-V Semiconductor Films
Authors: Maldonado Stephen
Published: February 2020

This presentation will describe our latest results on the concept of using liquid metal electrodes as platforms for direct electrodeposition of crystalline inorganic semiconductor materials at comparatively low temperatures.

Large scale production of crystalline thin films of III-V semiconductors is challenging in two ways. First, the majority of synthetic methods are energy- and resource-intensive. For example, vapor phase crystal growth techniques such as metal-organic vapor phase epitaxy and molecular beam epitaxy  involve ultra-high vacuum (UHV) equipment and temperatures above 400 °C. Similarly, liquid phase epitaxy requires sustained temperatures in excess of 750 °C and pressurized furnaces. Second, these same fabrication methods can be difficult to incorporate directly into device fabrication processes. For example, high temperatures and corrosive reagents can damage delicate electronic device architectures (e.g. complementary metal-oxide-semiconductor (CMOS)) and sensitive platforms (e.g. plastics). As a result, cumbersome and costly transfer and integration steps are necessary. Electrodeposition of III-V semiconductors has been extensively investigated since electrochemistry offers precise control of (heterogeneous) reaction rates and simple process electronics and equipment (i.e. a current or potential source and a beaker). However, stoichiometry, purity, and crystallinity have proven difficult to control.

Here, experimental data will be shown for a new tactic that offers the purity and quality of aforementioned high temperature, vapor-phase syntheses with the simplicity and affordability of conventional electrodeposition. Specifically, data will be presented that illustrates the preparation of polycrystalline films of GaAs, GaSb, InAs, InSb, and alloys thereof through an electrochemical liquid-liquid-solid (ec-LLS) process. Chronoamperometic and voltammetric responses recorded during ec-LLS will be shown. Materials characterization data in the form of electron & X-ray diffraction, X-ray photoelectron & Raman spectroscopies, and optical & electron microscopies will be also be discussed. Comparisons and distinctions with other, previously demonstrated electrochemical, chemical vapor deposition, and chemical metallurgical processes will be presented. The prospects for making high quality (epitaxial) III-V films and for seemless incorporation of III-V films on sensitive device platforms through ec-LLS will be discussed.
Solid-Electrolyte Interphase (SEI) Fracture: The Coupled Mechanical-Chemical Degradation of Lithium Ion Battery
Authors: Deshpande Rutooj , Bernardi Dawn
Published: February 2020

The coupled mechanical-chemical degradation of electrodes upon electrochemical cycling is recognized as a major challenge in lithium ion batteries. Instability of commonly employed electrolytes at the operating potentials results in solid electrolyte interphase (SEI) formation. Although, a stable SEI layer is necessary, as it passivates the electrode-electrolyte interface from further solvent decomposition, SEI formation also contributes to irreversible capacity loss. During electrochemical cycling, due to the volume changes of the electrode particles and the associated stresses within the SEI layer, the SEI layer may fracture, exposing new electrode surfaces to the electrolyte. A new SEI is formed at these newly exposed surfaces resulting in loss of active lithium inventory. We develop a mathematical model to calculate stresses and strain energy for a particleencapsulated with SEI during lithiation and delithiation. We show that, loss of capacity of a battery due to SEI fracture actually occurs during lithiation since SEI experiences high tensile stress suring electrode lithiation. We demonstrate that for slow lithiation, excess strain energy in the particle is proportional to square of State of Lithiation (SOL) swing. A corelation is developed to calculate the cell capacity loss due to SEI fracture as a function of SOL swing, and is compared with the experimental data. We found that the model fits the capacity loss data very well. This is the first physics based model which correlates SEI cracking with the cell capacity loss.
Comparison of Spatiotemporal Changes of Solid Electrolyte Interphase (SEI) Properties on Different Anodes By Scanning Electrochemical Microscopy (SECM)
Authors: Bülter Heinz , Wittstock Gunther , Peters Fabian , Schwenzel Julian , Sternad Michael , Wilkening Martin
Published: February 2020

In our society Li ion batteries are widely used. Mainly during the first charging process the solid electrolyte interphase (SEI) between the electrode and electrolyte is formed by the decomposition of electrolyte components at the lithiated graphite. This layer is critical for the performance and safety of the Li ion batteries.[1] The aim of this study is to characterize the electron transport across the SEI, which determines the ongoing reduction of electrolyte components. Thus, understanding the electron transport across the SEI helps to improve Lithium ion batteries.

Characterization of the SEI is a challenge, because of the variety of chemically similar components and enclosed electrolyte species. Furthermore, ex situ analysis of the SEI requires separation and isolation of the SEI, which may change the content and the structure of the SEI.[2] Recently we used the feedback mode of scanning electrochemical microscopy (SECM) to investigate in situthe electron transport at the lithiated graphite (Figure).[3]

2,5-di-tert-butyl-1,4-dimethoxy benzene was identified as an useful SECM mediator providing sufficient stability and sensitivity to study passivation properties of the SEI. Our results by SECM show gradual and significant short-term spatiotemporal changes of the SEI properties and demonstrate the dynamic and spontaneous behavior of SEI formation, damage and reformation under open circuit conditions above lithiated graphite anodes. The results emphasize that spatiotemporalchanges of the passivating SEI properties are highly localized and occur preferentially in between the gaps of graphite particles. A HOPG model electrode shows significant differences to a graphite composite electrode, indicating the impact of stressed graphite particles on the SEI stability. In addition, imaging experiments show the formation, detachment and reformation of gas bubbles.

The outcome of significant short-term spatiotemporalchanges of the SEI properties clarifies that electrolyte reduction still occurs after SEI formation at localized spots. All measurements were conducted under open circuit conditions and thus the charging state remained constant. Further research using this methodology focuses on Li and Si electrodes.

H.B. thanks the Lower Saxony Ministry of Science and Art for funding within the Graduate Program GEENI - Graduate school of electromobility and energy Storage in Lower Saxony. M.S. and M. W. gratefully acknowledge the provision of anode substrates by Infineon Technologies Austria AG.

References

[1] S. Krueger, R. Kloepsch, J. Li, S. Nowak, S. Passerini, M. Winter, J. Electrochem.
Soc.
160, 2013, A542.

[2] P. Verma, P. Maire, P. Novák, Electrochim. Acta
55, 2010, 6332.

[3] H. Bülter, F. Peters, J. Schwenzel, G. Wittstock, Angew. Chem. Int. Ed.
53, 2014, 10531.

Figure 1
Model-Based SEI Layer Growth in EV and Phev Batteries for Standard Drive Cycles
Authors: Lawder Matthew T , Subramanian Venkat R. , Northrop Paul W. C.
Published: February 2020

Capacity fade in electric vehicle batteries is caused through a number of mechanisms. Solid Electrolyte Interface (SEI) layer growth caused by side reactions at the battery anode is one of these mechanisms that results in loss of battery power and energy capacity. Reducing the growth of this layer can help increase battery life and overall utility of electric vehicles, especially near the end of their service life.

We use a model based approach to study how the SEI layer grows during different types of charging, specifically looking at how the regenerative braking portion of driving will contribute to SEI layer growth. Eight different drive cycles were used to analyze how different driving patterns contribute to SEI layer growth.

The battery model used for the study was a porous electrode pseudo two dimensional model.1 A mathematical reformulation of the model was used to increase computational efficiency and speed without greatly reducing model accuracy.2 Three different SEI layer growth equations from literature were studied for EV charging.3-5 SEI growth was studied for both charging and regenerative braking, during which the battery is being charged for short periods of time during driving cycles that are predominantly discharge.

Results show rates of SEI growth for driving duration (by time) and length (by distance traveled) and analyze similarities in the driving cycle characteristics that may lead similar SEI layer growth rates. Additionally, results look at the effects of different depth of discharge during cycling on the battery and how DOD affects the overall SEI layer growth.6

As EV batteries continue to go through cycles, the effects of SEI growth caused from different types of driving will become more pronounced. The results shown will help reveal how that SEI growth can be reduced through driving patterns.

References

1.             M. Doyle, T. F. Fuller, and J. Newman,  Journal of the Electrochemical Society,
140, (1993)

2.             P. W. C. Northrop, B. Suthar, V. Ramadesigan, S. Santhanagopalan, R. D. Braatz, and V. R. Subramanian,  Journal of the Electrochemical Society,
161, E3149(2014)

3.             P. Ramadass, B. Haran, P. M. Gomadam, R. White, and B. N. Popov,  Journal of the Electrochemical Society,
151, A196(2004)

4.             M. Safari, M. Morcrette, A. Teyssot, and C. Delacourt,  Journal of the Electrochemical Society,
156, A145(2009)

5.             M. B. Pinson and M. Z. Bazant,  Journal of the Electrochemical Society,
160, A243(2013)

6.             M. T. Lawder, P. W. C. Northrop, and V. R. Subramanian,  Journal of the Electrochemical Society,
161, A2099(2014)
Effect of Metal Nanoparticles on the Polysulfide Conversion Reactions in Rechargeable Li-Sulfur Batteries
Authors: al Salem Hesham , venkateswara Rao Chitturi , Ganguli Babu , Arava Leela mohana reddy
Published: February 2020

Rechargeable lithium-sulfur (Li-S) batteries have emerged as the most promising electrochemical energy storage systems due to their high energy density, wide range of temperature operation, cost effectiveness, and eco-friendly in nature. Nevertheless, the drawbacks associated with the Li-S batteries such as insulating nature of sulfur species, corrosive nature of predeposited polysulfides at electrodes during discharge-charge processes, and formation of thick SEI layer still need to be circumvented. One of the promising ways to alleviate these problems is to use highly porous, conductive, and active species which can improve the kinetics of polysulfide conversion reactions and diffusion processes. In this context, we have investigated electronically conductive species incorporated graphene, specifically Metal/graphene hybrids (metal = Pt, Ni, and Co) as cathode in Li-S batteries and performed systematic studies to understand the electrochemical behavior of polysulfides during discharge-charge processes.

Metal/graphene hybrids were prepared through wet chemical routes and employed them as electrodes for the conversion of polysulfides in Li-S batteries. Structural and morphological techniques depicted phase purity of the materials and well-dispersed metallic nanocrystallites with an average size of 5 nm on the graphene sheets. Electrochemical studies were carried out by assembling Li/sulfur cells inside glove box using a porous metal/graphene as electrodes cathode, 0.6M Li2S8-1M LiTFSI in TEGDME as electrolyte, and metallic lithium as anode. Galvanostatic discharge-charge tests indicated a two-fold increment in the Li-S battery performance with metal/graphene compared to pure graphene. A high discharge capacity of 750 mAh/g at C-rates of C/10 has been observed with Pt/graphene. The studies on metal/graphene based Li-S battery revealed pivotal role of metallic nanoparticles in enhancing the polysulfide conversion processes.

# - Corresponding Author - leela.arava@wayne.edu
Reactions Between Deliathidated Cathodes and Electrolytes
Authors: Chen Zonghai , Amine Khalil
Published: February 2020

The safety concern of lithium-ion batteries has been one of major technological barriers that hinder the deployment of lithium-ion batteries for automobile applications.  As an alternative to conventional thermal analysis techniques like differential scanning calorimetry and accelerating rate calorimetry, an in situ high energy X-ray diffraction technique was established to investigate the decomposition mechanism of delithiated cathode materials at thermal abuse conditions.  Figure 1 show a typical in situ high energy X-ray diffration data during the thermal abuse of delithated Li1.2Ni0.15Mn0.55Co0.1O2.  In this talk, the mass/charge transfer throught the material interface will be disccused to illustrated the degration mechanism of delithiated cathode materials.

Figure 1
Beyond State of the Art: A Family of Novel and Highly Performing Electrolytes for Rechargeable Magnesium Batteries Based on Boron-Hydrogen Compounds
Authors: Mohtadi Rana , Tutusaus Oscar , Arthur Timothy S. , Zhang Ruigang , Carter Tyler , Mizuno Fuminori
Published: February 2020

Owing to a high volumetric capacity (3833 mAh cm-3 vs. 2046 mAh mAh cm-3 for Li), absence of dendrites formation and lower cost of Mg metal (about 10 times cheaper than Li), rechargeable magnesium batteries have been receiving an increased attention.  One major challenge facing these batteries is related to the electrolytes as they are restricted to a handful of corrosive halogen based magnesium reagents and complexes.  Electrolytes based on conventional inorganic and ionic Mg salts, such as MgClO4, were found unsuitable due to their instability in the reducing environment of the Mg anode resulting in complete Mg passivation [1]. Overcoming the hurdles with current electrolytes calls for discovering new non-halo based systems that are compatible with Mg metal (Fig.1.a).  Recently, motivated by the thermal stability and a presumed robustness of the BH4
- anion against electrochemical reduction, we proposed magnesium borohydride as an electrolyte beyond state of the art for rechargeable magnesium batteries [2].  Owing to a high reductive stability, we discovered that magnesium borohydride could withstand the reducing environment of Mg metal making it the first and so far only example of an inorganic, relatively ionic and halide free salt that could function as an electrolyte in Mg batteries. This breakthrough offered a path towards designing non-corrosive electrolytes and has been used as a basis to create a whole new family of highly performing systems, Fig.1.a [3].  For example, to increase the anodic stability of the B-H bond while preserving the attractive features of BH4
- anion, icosahedral boron clusters were proposed.  Unlike the case in typical halo Mg reagents, which require the addition of a Lewis acid as AlCl3 to increase its anodic stability, we developed the Mg salt Mg(1,7-C2B10H11)Cl [3,4] that while displaying greater than 98% Mg deposition/stripping efficiency, demonstrates high anodic stability (3.2 V) and solubility (> 1M in tetrahydrofuran solvent) (Fig.1b).

Herein, we will explain our bottom up design strategies, discuss fundamental properties obtained from systematic spectroscopic and electrochemical studies and share up-to-date results related to these new promising systems.

References

 [1] a. H. D. Yoo, I. Shterenberg, Y. Gofer, G. Gershinsky, N. Pour, D. Aurbach, Energy Environ. Sci. 2013, 6, 2265-2279; b. R. Mohtadi, F. Mizuno, Beilstein J. Nanotechnol. 2014, 5, 1291 –1311.

[2] R. Mohtadi, M. Matsui, T. S. Arthur, S.-J. Hwang, Angew. Chem. Int. Ed. 2012, 51, 9780 –9783.

[3] O.Tutusaus, R. Mohtadi, ChemElectrochem, DOI 10.1002/celc.201402207,2014.

[4] T. J. Carter, R. Mohtadi, T. S. Arthur, F. Mizuno, R. Zhang, S. Shirai, J. W. Kampf, Angew. Chem. Int. Ed. 2014, 53, 3173 –3177; Angew. Chem. 2014, 126, 3237– 3241.

Figure 1