bluuebunny/crossref_metadata_2025 huggingface dataset:
Visualization of Liquid Water Distribution at Interfaces of PEFC by Using Parallel-Beam Soft X-ray Radiography
Authors: Naito Hiroshi , Jao Ting-Chu , Yoshida Toshihiko , Sasabe Takashi , Kawamura Katsuyuki , Hirai Shuichiro
Published: February 2020

Because of increasing expectation of the use of PEFC, further improvement of the performance is still demanded. Since the liquid water generation and its accumulation inside the PEFC is one of the most influential phenomena for the electric generation performances, it is required to obtain knowledge about the actual liquid water distribution inside the PEFC and its generation/drainage process in order to promote the efficiency of the PEFC. Particularly, the detailed liquid water behavior at the interfaces has not been provided in spite of its large impact on the liquid water drainage performances. By using soft X-ray radiography, our laboratory has reported liquid water distribution inside the PEFC. In principle, however, the conventional cone beam type X-ray used so far has difficulty to capture the interfaces because of the widening effect of the X-ray beam. This problem can be solved by parallel type X-ray beam. In this study, we introduce a parallel beam type X-ray microscope to improve the accuracy of the interface measurement. We especially focus on the liquid water distribution at the GDL/MPL/CL/membrane interfaces.

In this study, in-plane measurement is performed to obtain two-dimensional visualization having rib/channel configuration. The visualization result operated at 30℃ cell temperature, 80% relative humidity and 0.6A/cm2 current density, is shown in fig.1. In the wide region on the cathode rib, accumulation of liquid water is observed same as reported in some other previous studies. Also, it is clearly shown that, in the CL/MPL interface of cathode side, film-like water distribution is created due to capillary pressure gap. In the presentation we will also focus on the generation/drainage process of the liquid water including intermittent behavior on the interfaces.

This work is supported by the New Energy and Industrial Technology Development Organization (NEDO) of Japan.

Figure 1
The ARPA-E Ionics Program: Advancing Anion Exchange Membranes
Authors: Albertus Paul S. , Babinec Susan J. , Pouy Mark J.
Published: February 2020

In 2016 ARPA-E launched the IONICS (Integration and Optimization of Novel Ion-Conducing Solids) program, motivated by the enabling role of separator technology and the remaining performance and cost gaps across multiple types of electrochemical devices. The 16 teams in the IONICS program are focused on developing breakthrough separators that would be broadly enabling in different areas of electrochemical technology, and also amenable to cost effective manufacturing. The projects include both polymer and inorganic ion conducting separators that enable electrode chemistries that have been previously unsuccessful in practical devices. Project teams are focused on overcoming property tradeoffs to achieve a full set of required attributes, including conductivity, selectivity, stability, mechanical properties, manufacturability, cost, and others. This contrasts with a common approach of optimizing a single variable at the expense of others. The IONICS focus is on solids rather than liquids, due to inherent advantages in selectivity and mechanical properties offered by solids.

The IONICS program is focused on three areas: (1) Li+ conductors that enable the cycling of the lithium metal electrode at conditions required for high-energy cells, (2) highly selective polymer separators for flow batteries, and (3) anion-conducting polymer separators for use in alkaline fuel cells, electrolyzers, and other electrochemical devices. This talk will focus on area (3), where the potential benefits of the alkaline environment include the reduction/elimination of platinum-group metal catalysts for both hydrogen and oxygen electrodes, and the ability to use lower cost, uncoated, stainless steel plates. The polymer attributes pursued in the program include extended stability (1,000 h with negligible degradation) in alkaline conditions at a temperature of 80°C or higher, low area-specific ionic resistance (<=0.04 ohm-cm2 in liquid form), limited swelling (<50%), and low cost (<=20 $/m2). Additionally, fuel cell applications require the membrane to retain high conductivity under air exposure and avoid degradation during humidity cycling, while electrolysis applications require it to withstand a differential pressure of tens of bar. A key limitation for the development of improved membranes in this growing field is the lack of specific, consistent test conditions, which makes it difficult to easily identify the most promising membranes. This talk will outline the test conditions developed for the IONICS program teams, which we hope will be used by other research groups to advance progress in this important field.
Co,N-Codoped Mesoporous Carbon As Efficient Bifunctional Catalysts for Oxygen Reduction and Hydrogen Evolution Reaction
Authors: Liu Xiaojun , Zou Shouzhong
Published: February 2020

Pt-based catalysts have been extensively studied as polymer electrolyte fuel cell catalysts and hydrogen evolution reaction (HER) catalysts. However, the low abundance and high cost of these materials preclude their large-scale commercial applications. Alternative more sustainable catalysts are therefore needed. Various carbon-based materials have been demonstrated to have high oxygen reduction reaction activity especially in the alkaline media. In this work, we report a simple silica template approach to form porous carbon codoped with nitrogen and cobalt. The obtained porous carbon exhibited not only excellent electrocatalytic activities for ORR, which compare favorably with that of commercial Pt/C (20 wt%), but also superior durability and methanol tolerance. The porous carbon also possess superior performance for HER in acidic media, showing a low onset potential of only -0.04 V vs RHE, a Tafel slop of 57.4 mV dec-1, a current density of 10 mA cm-2 at -0.106 V vs RHE and remarkable durability. Thus, the Co, N-doped carbon holds great promise as bifunctional catalysts for regenerative fuel cells.
N-Cdot/Pd Nanosponge with Enhanced Electrocatalytic Activity for Hydrogen Evolution Reaction and Methanol Oxidation Reaction
Authors: Choi Ho-Suk , Nguyen Van-Toan
Published: February 2020

N-Cdot/Pd nanosponge was effectively synthesized by using N-doped carbon dots (N-Cdot) as a structure directing agent and L-ascobic acid as a reducing agent. The N-Cdot/Pd nanosponge electrode exhibited a low overpotential of -55 mV at a current density of 10 mAcm-2, while providing excellent stability for hydrogen evolution reaction in acidic conditions. In addition, the N-Cdot/Pd nanosponge electrode showed high catalytic activity and stability for the methanol oxidation reaction in 0.1 M KOH aqueous solution containing 1 M methanol. The high catalytic activity of the N-Cdot/Pd nanosponge is mainly due to the synergistic effect caused by intimate contact between the Pd and the N-doped carbon dots, as well as the larger electrochemically active surface area (ECSA) provided by the sponge structure.
Development of Carbon-Free Electrocatalysts for Water Electrolysis
Authors: Muto Marika , Sasaki Kazunari , Hayashi Akari
Published: February 2020

Introduction Hydrogen production from water electrolysis and further electricity generation through fuel cells have been focused on as one of the efficient uses of renewable energy. Regarding to water electrolysis, the PEM type water electrolyzer is attractive in terms of reduced ohmic resistance and also a similar assembly to well-developed PEFCs. On the other hand, the relatively low active surface area of anode electrocatalysts is a problem since carbon supports are not usable in order to disperse small catalyst particles under the high potential condition over 1.5 V. So far, our group has been working on mesoporous materials for PEFCs. We have found that mesoporous materials can keep those porous structures even after being built into the device, and then, the porous structure can improve the mass transfer within catalyst layers. Based on the similar idea used in our PEFC studies, we propose development of carbon-free mesoporous metal catalysts with high active surface area to increase the efficiency of water electrolyzer. In this study, mesoporous Pt and Ir materials were particularly developed and further evaluated as anode electrocatalysts.

Experimental method

Similar to the synthesis of mesoporous carbon,1 a surfactant, Pluronic F127, was used as a template to form a porous structure. Pt(acac)2 and Ir(acac)3 were used as metal precursors. After mixing the surfactant and metal precursors, the resultant complex was slowly heated up in N2or Air atmosphere to make the mesoporous structure. After the basic material characterizations, their electrochemical measurements were performed using a common half-cell setup in the solution. Oxygen evolution reaction (OER) activity was evaluated as anode electrocatalysts. The durability against high potential like 1.8 V was also analyzed.

Results and discussion

The resulting Pt material was confirmed to have a porous structure constructed by aggregation of Pt nanoparticles as shown in Figure 1. Based on the nitrogen sorption measurement, the randomly oriented porous structure was also confirmed, and the pore diameter was found mostly smaller than 100 nm. With this porous Pt material, OER activity was evaluated and compared with a standard Pt/KB electrocatalyst, TEC10E50E. As shown in Figure 2, the initial activity resulted in the same even though ECSA was six times higher for Pt/KB. Then, the durability of porous Pt and Pt/KB was examined by applying continuous high potential of 1.8 V. Dot lines in Figure 2 shows the OER activity after 10 minutes of holding at 1.8 V．As expected, Pt/KB lost most of OER activity owing to carbon corrosion. Consequently, carbon-free porous Pt electrocatalyst was successfully prepared and its high activity and durability was confirmed. Similarly, porous Ir electrocatalyst is prepared and its OER activity will be discussed.

Reference

(1) A. Hayashi, et al., Electrochim. Acta,
53, 6117-6125 (2008).

Figure 1
Two-Dimensional Iridium-Nickel-Oxide Nanoframes for High Activity Oxygen Evolution Electrocatalysts
Authors: Rhodes Christopher , Godinez-Salomon Fernando , Albiter Luis
Published: February 2020

Oxygen evolution electrocatalysts with high activity and stability are needed for proton-exchange membrane (PEM) electrolyzers. Iridium oxide (IrOx) has been shown to exhibit both high activity and stability for the oxygen evolution reaction (OER) under acidic conditions. Based on the high cost and limited supply of IrOx, approaches that increase the activity of Ir-based OER catalysts are of significant interest. Recent work has shown that incorporation of Ni within the IrOx structure increases the OER activity.1 Further, the activity of IrOx has been shown to depend on specific surface structures (i.e. edges, corners and facets).2 As an approach to provide high activity OER catalysts, we investigated a unique self-supported IrNixOy two-dimensional (2D) nanoframe structure that allows the combination of (i) incorporation of a non-noble transition metal within the structure to tune the surface atomic and electronic structure, (ii) expression of specific facets and edges, and (iii) an interconnected, carbon-free three-dimensional matrix that allows molecular accessibility. The IrNixOy 2D nanoframes were synthesized by using nickel hydroxide/oxide nanosheets that were decorated with Ir and then treated under controlled temperature/atmosphere treatments to facilitate Ir-Ni interaction. The development of IrNixOy 2D nanoframes extends our group’s recent work on bimetallic Pt-Ni 2D nanoframes which were shown to exhibit high stabilities and activities for the oxygen reduction reaction.3 The 2D nanoframe structure provides an architecture that expresses highly catalytically active surfaces within an interconnected solid and pore network that faciliates molecular access to the reactive surface. The structure of the IrNixOy 2D nanoframes was determined using X-ray diffraction, scanning transmission microscopy, and scanning transmission electron microscopy. Oxygen evolution activities and stabilities were determined using rotating ring disk electrode configuration and will be presented. The ability to combine highly catalytically active surfaces within a 3D nanoarchitecture provides the opportunity to design OER catalysts with improved activity and stability.

References

1. Sen, F. G.; Kinaci, A.; Narayanan, B.; Gray, S. K.; Davis, M. J.; Sankaranarayanan, S.; Chan, M. K. Y. J. Mater. Chem. A
2015,
3, 18970-18982.

2. Reier, T.; Pawolek, Z.; Cherevko, S.; Bruns, M.; Jones, T.; Teschner, D.; Selve, S.; Bergmann, A.; Nong, H. N.; Schlogl, R.; Mayrhofer, K. J. J.; Strasser, P. J. Am. Chem. Soc. 2015, 137, 13031-13040.

3. Godínez-Salomón, F.; Mendoza-Cruz, R; Arellano-Jimenez, M.J., Jose-Yacaman, M.; Rhodes, C.P. (manuscript submitted).
(Invited Plenary) U.S. Department of Energy Hydrogen and Fuel Cell Activities: Progress and Opportunities
Authors: Satyapal Sunita , Miller Eric L. , Papageorgeorgopoulos Dimitrios , Stetson Ned T
Published: February 2020

The fuel cell industry is poised for significant expansion—with more than 830 patents issued in 2015, second in the clean energy sector only to solar. Global shipments were at 60,000 units worldwide in 2015 with an annual growth of roughly 30 percent every year since 2010, and annual revenues have exceeded $2 million. After decades of research and development (R&D), fuel cell electric vehicles using hydrogen are now commercially available. They achieve significantly higher efficiencies than combustion engines, offering zero-petroleum and zero-emissions driving options with performance meeting consumer expectations – over 360 mile driving range, a few minutes to refuel, and the high torque and quiet characteristics of all-electric platforms. Such characteristics also enable a number of other applications, such as stationary or backup power, auxiliary power, underwater and aircraft systems, trucks, rail, soldier portable power, and remote surveillance systems.

This plenary presentation will provide an overview of the U.S. Department of Energy (DOE) hydrogen and fuel cell activities with a focus on transportation and early market applications, highlighting key progress as well as opportunities. Recent efforts include DOE’s national lab-led consortia, offering state-of-the-art multi-lab core capabilities and leveraging university and industry partners to accelerate materials breakthroughs and innovations in three key areas: ElectroCat, for platinum group metal-free catalysts, HydroGen for advanced water-splitting, and HyMARC for hydrogen storage materials research. A summary of the H2@Scale concept will be provided which lays a framework for the potential wide-scale production and utilization of hydrogen to address key issues such as grid resiliency, energy security, and cross-sectoral emissions reductions. In addition to an overview of current status in commercial developments, the focus will be on key challenges requiring transformational early stage applied research and development. Examples include catalysts, membranes, electrode structures, as well as electrolysis and other advanced water-splitting approaches. Low cost and reliable hydrogen delivery technologies including high efficiency liquefaction, advanced compression such as electrochemical compression, and advanced dispensing technologies will also require R&D relevant to the electrochemistry, chemistry, and engineering research community.
Operando and in Situ Diffraction Investigation of Lithium-Ion Batteries: What Have We Learnt over the Years and Where Are We Heading?
Authors: Sharma Neeraj
Published: February 2020

A large proportion of the function of batteries arises from the electrodes, and these are in turn mediated by the atomic-scale perturbations or changes in the crystal structure during an electrochemical process (e.g. battery use). A range of researchers have applied operando and in situ diffraction to probe electrode crystal structure evolution during electrochemical processes inside fully functioning batteries. This allows the direct correlation of structural, electrochemical and external parameters, e.g. atomic site occupancies, applied current and temperature, which provides a relatively holistic picture of electrode function.

This talk is divided into two parts, the first delving into the history of operando/in situ diffraction based techniques used to study lithium-ion batteries, encompassing X-ray, neutron and electron diffraction. I will highlight selected developments, recent breakthroughs, and key considerations required for carrying out these studies, including but not limited to cell design and choice of instrument. The second part of the talk will showcase our recent work in this space, trying to push the boundaries of these experiments. Here we are exploring aspects such as battery types with a range of form factors, i.e., thin-film to large format, the influence of temperature whilst performing in situ experiments, long term in situ experiments and particularly pertinent to applications the high-current rate behaviour of electrodes and their relationship to structural evolution or stability.

The presentation will provide a critical snapshot of how operando and in situ diffraction methods ar contributing to the development of lithium-ion batteries.
Novel Analytical Method in Revealing the Solution Structure of Lithium-Ion Battery Electrolytes
Authors: Su Chi Cheung , Amine Rachid , He Meinan , Chen Zonghai , Amine Khalil
Published: February 2020

Lithium-ion batteries have been widely applied in portable electronics due to its high energy density. [1] It is essential to improve the state-of-the-art LIBs, which are far from their maximum theoretical energy density, in order to power up electric vehicles. [2] Researchers have shown that the physiochemical properties, such as conductivity, electrochemical window and ability to form solid electrolyte interphase (SEI), depend on the solution structures of the electrolyte. [3] Thus, it is crucial to determine the solution structures of the electrolyte and the relative solvating ability of various solvents for designing advanced electrolyte systems.

Novel method utilizing specific 2D-NMR technique was successfully developed to probe the solvation state of different electrolyte solvents. The result obtained by this technique agreed with the measurement by vibrational spectroscopy. Most importantly, unlike the vibrational spectroscopy measurement, this method can be easily applied to electrolyte system with two or more electrolyte solvents. For example, it is not impossible to determine the solvation state of a ternary-solvent electrolyte comprising EC, EMC and DMC by vibrational spectroscopy due to the severe overlapping of peaks. However, the solvation state can be easily determined with the new method developed. Therefore, this new technique provides an important experimental tool in examining the solvation state of different electrolyte solvents. Application of this newly developed technique in revealing the electrochemical performance of various electrolytes on Li-ion batteries will also be discussed.

References:

[1] (a) Tarascon, J.-M.; Armand, M., Issues and Challenges Facing Rechargeable Lithium Batteries. Nature
2001, 414, 359-367. (b) Armand, M.; Tarascon, J.-M., Building Better Batteries. Nature
2008, 451, 652-657.

[2] Goodenough, J. B.; Park, K.-S., The Li-Ion Rechargeable Battery: A Perspective. Journal of the American Chemical Society
2013, 135, 1167-1176.

[3] (a) Seo, D. M.; Reininger, S.; Kutcher, M.; Redmond, K.; Euler, W. B.; Lucht, B. L., Role of Mixed Solvation and Ion Pairing in the Solution Structure of Lithium Ion Battery Electrolytes. The Journal of Physical Chemistry C
2015, 119 (25), 14038-14046. (b) Xu, K., Electrolytes and interphases in Li-ion batteries and beyond. Chemical reviews
2014,
114 (23), 11503-618.
Renewed Interest in Sulfone-Based Electrolytes for 5V Li-Ion Batteries
Authors: Schroeder Marshall , Alvarado Judith , Borodin Oleg , Meng Ying Shirley , Xu Kang
Published: February 2020

Harnessing the enhanced energy and power metrics offered by “5V-class” lithium-ion electrode chemistries relies on development of more robust electrolytes with expanded voltage and temperature stability windows. As a part of this effort, electrochemists have explored the promise of sulfones, highlighting their oxidative stability (generally >5.0V vs. Li/Li+ compared to ~4.3V for conventional electrolytes), safety, and compatibility with high voltage systems. Unfortunately, due to their high melting points, viscosity, and inability to independently form a stable solid electrolyte interphase (SEI), practical implementation of sulfones has generally been limited to use as minority co-solvents in more conventional electrolyte systems.

In this work we explore the effects of solvation, concentration, and salt chemistry on sulfone-based electrolyte performance. In graphite anode half-cells, we characterize the formation of a stable SEI which enables full utilization of the graphite electrode for the first time in an electrolyte with a sulfone as the primary solvent. In high voltage full cells, the oxidative stability of the system is confirmed by voltammetry and galvanostatic cycling measurements. Anode and cathode surface chemistry is explored extensively with XPS, and coupled with computational calculations, a mechanism for the formation and operation of both electrode/electrolyte interphases is proposed. These results suggest sulfones warrant continued consideration as a system for enabling safe, high performance, next generation Li-ion batteries.
Anodes for Lithium Ion Batteries Produced from Recovered Silicon Powders
Authors: Mokkelbost Tommy , Wagner Nils P. , Sheridan Edel , Tolchard Julian Richard , Noja Gianluigi , Bellmann Martin
Published: February 2020

Lithium Ion Batteries (LIB) offers the highest energy density among rechargeable batteries technologies. However, improvement in materials are needed for LIB in order to increase energy density, safety, durability, decrease cost and allow the further deployment of technologies like electric vehicles and energy storage. One way to improve these batteries is to develop new electrodes, both cathode and anode, resulting in higher energy density. Graphite is today used as anode materials, but Silicon has been extensive studied due to their approximately 10 times higher gravimetrical capacity. However, it is well known that silicon has challenges related to volume expansion during (de)lithiation upon cycling. Several proposed solutions, like nanostructuring, nanowires, encapsulation etc. have been proposed. Here we present initial work, using Silicon kerf (recovered Silicon powders from cutting of silicon ingots).

Silicon kerf was delivered by the ECOSOLAR partner Garbo S.r.l. and the materials were cleaned to remove most of the impurities. The electrochemical performance of Silicon kerf was investigated in half cells. The silicon was mixed with Super C 65 carbon black as conducting agent and Na CMC as binder. Na CMC was dissolved in an aqueous solution containing KOH and citric acid at pH 3 to facilitate chemical bonding between the binder and the active material. Electrodes were fabricated by tape casting on plain Cu foil as current collector. Casts with varying thickness were produced to investigate the effect of electrode loading. C2016 coin cells was prepared using electrolyte consisted of 1M LiPF6 dissolved in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (1:1 by vol) added 5 wt% FEC (fluoroethylene carbonate).

Initial studies for using silicon kerf as a source for high capacity anode materials in lithium ion batteries has demonstrated that kerf should be evaluated further to determine the long time cycling stability of this materials. The materials were evaluated both to determine the maximum capacity and stability using capacity limited cycling. The electrodes using Si kerf were stable for 150 cycles during capacity limited cycling using a loading of 0.6 mg/cm3 and a bit lower cycle stability for electrodes with higher loading. It must be highlighted that the electrode structures and composition, electrolyte composition etc. has not been optimized.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 679692.
Intrinsic Challenges in Creating a Reversible Copper(II) Fluoride Cathode for Lithium-Ion Batteries
Authors: Zagarella Nikolas , Omenya Fredrick , Whittingham M. Stanley
Published: February 2020

Copper(II) fluoride (CuF2) is a promising cathode material for the next generation of lithium-ion batteries due to its high theoretical gravimetric (1645 Wh·kg-1) and volumetric (3797 Wh·L-1) energy density. In theory, it can reversibly store two incoming lithium ions in what is referred to a conversion reaction (2 Li+ + CuF2 + 2 e- → 2 LiF + Cu0). Although near-theoretical capacity (~515 mAh·g-1) has been achieved for the first discharge, capacity greatly decreases with every cycle thereafter. This is surprising as materials such as iron(II) fluoride, which undergo a similar reaction (2 Li+ + FeF2 + 2 e- → 2 LiF + Fe0) can easily achieve 10 cycles without any major capacity degradation. The lack of reversible capacity in CuF2 may be due to irreversible crystal structure changes inside of cathode which inhibit delithiation upon charging or due to the loss of copper through the electrolyte. Evidence for the latter for this can be seen through the copper plating of the lithium metal anode after cycling, detected by energy dispersive x-ray spectroscopy (EDS) analysis, or through the decrease in copper peak intensity in X-ray diffraction (XRD) and EDS spectra of the cathodes upon recharging. Correlation of copper content to capacity suggests that copper loss from the cathode is not the only factor in capacity loss and scanning electron microscopy (SEM) imaging shows large morphological differences between a pristine and charged sample. Decoupling these two intrinsic challenges for CuF2 batteries will enable the design of more reversible conversion reaction cathode materials in the future. For now, application of CuF2 in primary lithium-ion batteries remains promising, and continues to be expanded upon today.

This work is supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) program under Award No. DE-EE0006852.
Mitigation of Failure Propagation in Multi-Cell Lithium Ion Batteries
Authors: Torres-Castro Loraine , Lamb Joshua , Steele Leigh Anna M , Quintana Genaro , Grosso Christopher , Stanley June
Published: February 2020

Lithium ion batteries are one of the main energy storage devices that have the potential to be fully integrated in electric grid applications and electric vehicles. Despite years of research in battery safety, there are still challenges associated with the complexity of system-level safety for large battery systems. There is a major gap of safety knowledge at the module or pack level on the effects on adjacent cells in a large-scale battery pack as one cell experiences failure. After the impacts and consequences are identified it is also important to determine mechanisms to mitigate the effects of a single cell failure to the entire pack. In this study, we analyze the failure behavior of small battery packs with 5 stacked pouch cells (LiCoO2 cathode, 3Ah) after thermal runaway is induced to a single cell with nail penetration as the failure initiation method. The first part of the study was to determine the SOC in which full propagation was identified. Different states of charge were tested, including 50%, 75%, 80% and 100% SOC. Complete propagation was observed for 80% and 100 % SOC as shown in Figure 1. The second part of the investigation focused on identifying passive thermal management approaches to mitigating failure propagation. Figure 2 presents the preliminary results using an aluminum heat sink, in which partial propagation was achieved. The results of this study could provide insightful information of the impacts of single battery failure in a pack and a base for future battery designs.

Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

Figure 1
Silicon Nanowire Cocooned in Graphene like Carbon with One-Dimensional Si Anode for Lithium-Ion Battery
Authors: Lim Seh-Yoon , Whang Dongmok
Published: February 2020

Silicon (Si) is considered as next-generation material of the anode because it is rich in nature resource and its high theoretical capacity (4200 mAh/g), which is ten times higher than of commercial graphite anode (372 mAh/g). However, Si suffers a large volume expansion (approximately 400 %) during cycling process. As a result, it induces pulverization of silicon and causes to rapid capacity fading. This study describes controlled fabrication of one-dimensional silicon nanowires (SiNW) cocooned in graphene-like carbon sheath (SiNW@V@GS) for the improved electrochemical performance of Si anode. The specific new advances demonstrated are included in this work. First, the design of the one-dimensional morphology (SiNW@V@GS) for highly conductive network with Si core for high capacity, graphitic carbon sheath for better electrical conductivity and void space for compensation of large volume expansion during the cycling process. Second, we controlled void space between Si core and graphitic carbon sheath by adjusting oxidation time of Si core during CVD process and enabled electrode fabrication with high capacity and stable cycling performance. Finally, we developed facile and scalable synthesis of the prepared SiNW@V@GS materials by using the SiO2 template through successive CVD growth and chemical vigorous etching process.

Figure 1
Liquid Exfoliation of Interlayer Spacing-Tunable 2D Vanadium Oxide Nanosheets: High Capacity and Rate Handling Li-Ion Battery Cathodes
Authors: Zhang Chuanfang (John)
Published: February 2020

With a layered crystal structure and good Li+ storage performance, vanadium pentoxide (V2O5) is potentially a high-energy and cost-effective cathode material for Li-ion batteries (LiBs). Networks of two-dimensional V2O5 nanosheets (2D V2O5 NS), with large interlayer distance, are ideal for enhancing the Li+ diffusion kinetics and thus for building high power LiBs. However, the lack of a simple, scalable and environmentally friendly route to nanosheet production still hinders the development of V2O5 applications. Here we demonstrate, liquid-phase exfoliation (LPE) of commercial V2O5 powder in environmental friendly solvents (water and ethanol) to achieve large quantities of 2D V2O5 NS colloidal solutions. The V2O5 NS are of high-quality, orthorhombic whose interlayer spacing can be well manipulated, ranging from 4.4 Å to 11.5 Å in ethanol and water, respectively. Ultrasonic aerosol printing of V2O5 NS/single-wall carbon nanotube (SWCNT) blended solutions resulted in large-area, flexible, and binder-free hybrid electrodes, which showcase a high discharge capacity of 370 mAh g-1 at 0.05 C, high energy density (1110 Wh kg-1) and power density (4350 W kg-1), etc. These properties can be attributed to the synergistic effects between the expanded hydrated NS and the conductive SWCNT matrix; the latter improves the reversible phase transition reactions of the NS, enhances the ion diffusion kinetics, maintains the electrode’s mechanical integrity and provides electron transport pathways. We believe the LPE/aerosol printing approach is environmentally green, general and scalable, and could be extended to other layered transitional metal oxides or dichalcogenides for fabrication of corresponding flexible, binder-free, conductive composites for energy storage systems.
(Invited) Photoluminescence, Optically Stimulated Luminescence and Radiophotoluminescence of Storage Phosphors – a Lecture Learnt from Lu2O3:Tb, Lu2O3:Pr and LuPO4:Eu
Authors: Zych Eugeniusz , Kulesza Dagmara , Bolek Paulina , Zeler Justyna , Bos Adrie J.J. , Ueda Jumpei
Published: February 2020

We have been working on the Lu2O3:Ln,M (Ln= Pr/Tb, M= Ca, Sr, Ba, Ti, Hf, Nb, Ta) storage and persistent phosphors for more than ten years now. More recently we have discovered that also LuPO4:Eu shows ability to store energy when exposed to ionizing radiation. All the compositions share some characteristics. For example, they need high-temperature treatment to efficiently store energy and they do not degrade after over-exposure to ionizing radiation. What else all these compositions have in common is developing a broad absorption in UV-Vis part of spectrum during energy storage. These bands intensities mirror the dose of high-energy radiation they are exposed to. Figure 1 presents absorption spectra of Lu2O3:Tb,Hf (left) and LuPO4:Eu (right) storage phosphors before and after their exposure to X-rays. Despite some differences, in both cases ionizing radiation induced a broad absorption band extending in NUV-Vis (Lu2O3) or whole Vis (LuPO4) part of spectrum. In our presentation we shall analyze the origin of the new absorption bands in both compositions and will relate them to the energy storage mechanisms. We will also analyze their usability for optically stimulated luminescence or radiophotoluminescence generation in the materials.

The authors gratefully acknowledge ﬁnancial support by the Polish National Science Centre (NCN) under the grant #UMO-2014/13/B/ST5/01535.

Figure 1
(Invited) Overview of Different Schemes for Temperature Sensing from Luminescence of Lanthanide Doped Materials
Authors: Dramicanin Miroslav
Published: February 2020

This lecture gives an overview of methods which are currently in use for measurements of temperature from luminescence of lanthanide doped materials.1 Methods are classified to time-integrated and time-resolved ones depending on the temporal nature of luminescence measurements. The former methods include methods based on temperature reading from intensity of emission, ratio of emission intensities, changes of excitation and emission band positions and linewidths with temperature. The later include methods based on measurements of emission decay- and rise-times. Advantages/disadvantages between time-integrated and time-resolved temperature read-outs are highlighted, and the generic luminescence thermometry system is presented with a description of its basic components. Examples of temperature read-out schemes are given for each method of temperature reading, for low-, room- and high-temperature measurements. Examples include results obtained with: Dy3+ doped GdVO4 thin films,2 Yb3+/Er3+ doped GdVO4 nanoparticles,3 Eu3+ and Sm3+ doped TiO2 nanoparticles,4,5 Eu3+ doped SrY2O4,6 and Yb3+/Er3+, Yb3+/Ho3+ and Yb3+/Tm3+doped Y2O3.

References:

1. Dramićanin MD. Methods Appl Fluoresc 2016;4(4):42001 (23pp).

2. Antić Ž, Dramićanin MD, Prashanthi K, Jovanović D, Kuzman S, Thundat T. Adv Mater 2016;28(35):7745–52.

3. Gavrilović TV, Jovanović DJ, Lojpur V, Dramićanin MD. Sci Rep. 2014;4:4209 (9pp).

4. Nikolić MG, Antić Ž, Ćulubrk S, Nedeljković JM, Dramićanin MD. Sensors Actuators B Chem 2014;201:46–50.

5. Dramićanin MD, Antić Ž, Ćulubrk S, Ahrenkiel SP, Nedeljković JM. Nanotechnology 2014;25(48):485501.

6. Lojpur V, Antić Ž, Dramićanin MD. 2014;16(46):25636–41.
Electrochemical Cycling Process for Ammonia Synthesis Using N2 and H2o at Atmospheric Pressure
Authors: McEnaney Joshua M , Singh Aayush R. , Schwalbe Jay , Kibsgaard Jakob , Lin John , Cargnello Matteo , Jaramillo Thomas F , Nørskov Jens
Published: February 2020

Conventional ammonia synthesis via the Haber Bosch process facilitates fertilizer production to sustain the massive and growing human population. The massive scale of ammonia production of consumes over 1% of the entire global energy supply and releases ~450 million metric tons of CO2 into the atmosphere each year due to its dependence on fossil fuels for H2 production. In this work, we demonstrate a generalized alternative pathway toward sustainable ammonia synthesis via an electrochemical cycling strategy. This electrification strategy is amenable to be powered by renewable energy and to be locally implemented where the ammonia fertilizer needed by circumventing the high pressure and H2 gas requirements of the Haber Bosch process and instead using electricity and H2O. The process can be summarized by three distinct steps of surface preparation, nitrogen activation, and ammonia synthesis which can be combined and cycled for continuous ammonia production. The feasibility and general applicability of this cycle were evaluated with theoretical analyses. The process steps are characterized with specific electrochemical and materials chemistry techniques. Ammonia is quantified by UV-Visible colorimetric analysis and confirmed to be from N2 via isotopic labeling in Fourier transform infrared radiation studies. We experimentally demonstrate an initial current efficiency of 88.5% toward ammonia production via this process and we begin to evaluate the potential of this strategy for viability.
Determination of Manganese in Whole Blood By Stripping Analysis with Indium Tin Oxide
Authors: Rusinek Cory Allen , Kang Wenjing , Becker Michael , Wehring Bettina , Papautsky Ian , Bange Adam , Heineman William R. , Schuelke Thomas
Published: February 2020

Manganese (Mn) is a required trace metal in the body. In recent years however, it has garnered significant attention as a developmental neurotoxin in children with chronic exposure. It has been linked to complications such as memory loss with negatively associated IQ scores, attention deficit hyperactivity disorder (ADHD), and in extreme cases, the development of a Parkinson’s disease analogue- manganism. For these reasons among others, the Environmental Protection Agency has set the maximum contaminant level (MCL) in drinking water at a very low concentration of 50 ppb (0.9 μM). Thus, trace detection of this neurotoxic metal in both environmental and biological samples has become very important. Cathodic stripping voltammetry has proven to be a suitable method for electroanalytical determination of Mn. We have established Mn CSV using indium tin oxide (ITO) as the working electrode for the determination of Mn in bovine whole blood after an acid digestion. Reliable, accurate, and precise results were obtained as only 9% variation in the digested blood was observed. The CSV results were compared with graphite-furnace atomic absorption spectroscopy (GF-AAS) and inductively coupled plasma- mass spectrometry (ICP-MS) and favorable agreement across the methods was observed. We also fabricated ITO on non-optically transparent substrates where we observed improved electrochemical response compared to that of commercially available ITO. This was completed by varying pre-treatments, fabrication processes, and post-processing of the ITO electrodes. Due to ITO’s excellent positive potential window and stability under harsh environments, this method could be applied to other oxide-forming transition metals detectable by CSV.

Figure 1
Ar Plasma Exfoliated Nickel Iron Layered Double Hydroxide Nanosheets into Ultrathin Nanosheets As Highly-Efficient Electrocatalysts for Water Oxidition
Authors: Wang Yanyong , Wang Shuangyin
Published: February 2020

Designing electrocatalysts for oxygen evolution reaction with low cost, high activity and stable are crucial extremely to water splitting. Layered double hydroxides (LDHs) as a electrocatalyst exhibits a good oxygen evolution reaction (OER) performance because of its unique 2D lameller and electronic structure. However, the bulk NiFe LDHs nanosheets with large lateral size and bulk thickness hindering the exposition active sites reduce the electrocatalytic activity. To solve this problem, herein, the bulk NiFe LDHs nanosheets were successfully exfoliated into 2D ultrathin NiFe LDHs nanosheets by one-step Ar plasma. This electrocatalyst with a structure of ultrathin nanosheet and exposed more edge sites was synthesized by the Ar plasma treatment and was used to catalyze the oxidation of water. This unique structure of NiFe LDH increases the surface area and the exposure of active sites which extremely facilitate to improve the electrocatalytic performance for oxygen evolution reaction. In additions, Ar plasma also futher etched the basal planes of 2D crystals leading to production of more edge sites. Enormous studies have confirmed that positions in edge have much higher catalytic activity than positions in the basal planes. Therefore, this ultrathin NiFe LDHs nanosheets with rich edge sites as electrocatalyst showed a good OER activity with a low overpotential of 278 mV at 10 mA/cm2.

Figure 1
Effect of Surface Binding on Individual Bacterial Cells: Raman and AFM Approaches
Authors: Lebedev Nikolai , Tender Leonard M
Published: February 2020

Bacterial cell polarity is an internal cell asymmetry that correlates with the cell ability to sense energy and metabolite sources, chemical signals, quorum signals, toxins, and movement in the desired directions. This ability also plays central role in cell attachment to various surfaces and biofilm formation. Biochemical analysis and molecular imaging demonstrate that sensing of energy and nutrients by the cell correlates with asymmetric protein, lipid and other molecule distributions within the cell. In the present work, we develop an experimental approach and analyze how attachment to inorganic mineral, mica affects Cyt redox state inside individual G. sulfurreducens cells. The approach is based on confocal Raman microscopy allowing for simultaneous detection of Raman spectra of individual bacterial cell and the substrate and allowing for precise estimation of the border between them. Applying Gaussian deconvolution and principal component analysis we are able to identify spectral signatures of cytochrome redox states and their intracellular location. Our results demonstrate that attachment of G. sulfurreducens cells to a muscovite (mica) selectively changes Cyt redox state at the cell side facing the mineral. This leads to the formation of a gradient of redox potential needed for directed electron transfer within the cell. Our results open the possibility for analyzing electrochemical potentials inside individual bacterial cells. They indicate that Cyt redox state might be a driving force switching cell metabolic activity that leads to irreversible cell attachment to electrode, cell-to-cell association, and biofilm formation.
In-Situ THz SERS Observation of Electrochemical Processes
Authors: Inagaki Motoharu , Ikeda Katsuyoshi
Published: February 2020

Surface-selective vibrational spectroscopy is a powerful tool to study various interfacial phenomena such as electrochemical reactions at electrode-electrolyte interfaces. Among various spectroscopic methods, surface enhanced Raman scattering (SERS) is a promising method for in-situ observation of electrode-electrolyte interfaces because both of the incident and scattered photons utilized in this method has much higher energy than the molecular vibration energy. According to recent technological advancements in fabrication of optical filters, elimination of Rayleigh scattering has become highly efficient. Thus, it is now expected that very low-frequency vibrations such as THz vibrations can be observed even in aqueous solutions. In this talk, we demonstrate in-situ observation of THz vibrations in electrochemical conditions using SERS spectroscopy.

Figure. THz-SERS spectra of 4-methylbenzenthiol monolayers on Au(111), Au(100), and roughened Au substrates

Figure 1
Highly Efficient Photoelectrochemical and Photocatalytic Anodic TiO2 Nanotube Layers with Additional TiO2 coating
Authors: Sopha Hanna , Krbal Milos , Ng Siowoon , Prikryl Jan , Zazpe Raul , Macak Jan M.
Published: February 2020

The self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 10 years motivated for their possible range of applications including photo-catalysis, solar cells, hydrogen generation and biomedical uses [1]. The synthesis of 1D TiO2 nanotube structure is carried out by a conventional electrochemical anodization of valve Ti metal sheet. The main drawback of TiO2 is its applicability in the UV light (wavelengths < 390 nm). In order to enhance the efficiency, TiO2 has been doped by N [2] or C [3] o to shift its absorption into the visible light.

Except of doping, one of the major issues to extend the functional range of nanotubes is to coat homogenously tube interiors by a secondary material. It has been shown that additional ultrathin surface coating of TiO2 by secondary materials such as Al2O3 [4], ZnO [5] or MgO [6] annihilates electron traps at the TiO2 surface and thus increases the photogenerated concentration of charge carriers. Recently, it has been demonstrated that just a single cycle of Al2O3 [7] or ZnO [5] deposited by atomic layer deposition (ALD) efficiently improve charge transport properties of the heterostructure while gradual passivation appears with increasing ZnO thickness due to stronger band-bending [5].

The presentation will focus in detail on the coating of the nanotube arrays by secondary materials using ALD. The deposited materials influence strongly photo-electrochemical properties of nanotube films. Experimental details and some very recent photocatalytic [8] results will be presented and discussed.

References:

[1] J. M. Macak et al., Curr.
Opin. Solid State Mater.
Sci. 1-2 (2007) 3.

[2] C. Burda et al., Nano Lett. 3 (2003) 1049.

[3] S. Sakthivel et al., Angew. Chem., Int. Ed. 42 (2003) 4908.

[4] R. Zazpe et al., Langmuir, in press, DOI:10.1021/acs.langmuir.6b03119.

[5] A. Ghobadi et al., Scientific Reports 6 (2016) 30587

[6] H. Park, et al., Journal of Electroceramics 23 (2009) 146.

[7] J-Y. Kim et al., Nanotechnology 25 (2014) 504003.

[8] M. Krbal et al., Ms submitted.
(Invited) Photoelectrochemical Hydrogen Evolution Using Heterostructure of Si with Binary Cobalt SulﬁDe or Ternary Cobalt PhosphosulﬁDe
Authors: Liu Ru-Shi , Hu Shu-Fen
Published: February 2020

Development of a solar water splitting device requires design of a low-cost, efficient, and non-noble metal compound as alternative to noble metals. Here we will demonstrate that binary cobalt sulﬁde or ternary cobalt phosphosulﬁde can function as co-catalyst in phototoelectrochemical hydrogen production. We designed a heterostructure of p-Si and binary cobalt sulﬁde or ternary cobalt phosphosulﬁde solar-driven hydrogen production. These two types of co-catalysts successively coupled with p-Si can act as a superior photocathode in solar-driven water splitting reaction.