bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Temperature, Magnetic Field, and Dimensionality Effects on the Raman Spectra of TaSe2
Authors: Hight Walker Angela R. , Simpson Jeffrey R , Chowdhury Sugata 
Published: February 2020

In bulk form, TaSe2 exhibits transitions between commensurate and incommensurate charge-density wave (CDW) phases, and is attracting interest for advanced device applications. In order to explore the evolution of the groundstate CDW phase with layer number, mechanical exfoliation of bulk crystals provides few- to single-layer flakes. In the present work, we extend our opto-thermal Raman measurements1 on MoS2 to include other TMDs, specifically TaSe2 in both 1T and 2H crystallographic phases. A novel, magneto-Raman microscope system affords measurement of low-frequency (down to 10 cm-1) vibrational modes as a function of: temperature (100 K to 400 K), magnetic field (0 T to 9T) and laser excitation. The dependence of the observed Raman-active phonons on temperature and magnetic field will be discussed and compared with earlier results on MoS2. Specifically, we observe the appearance of low-frequency, zone-folded modes in the CDW state, which soften with temperature similar to the higher frequency, in-plane E2g mode. Additionally, we compare the measured magneto-Raman results to calculations using ab initio, density functional theory.

1ACS Nano 2014 8, 986
Electrochemical Property of Platinum Supported on Thiol-Attached Reduced Graphene Oxide Composite Electrode for Fuel Cells
Authors: Kim Seok , Kwon Sung Sang , Woo Joo Hyeong , Jung Yongju 
Published: February 2020

The direct methanol fuel cells (DMFCs) have been received much attention as promising energy converters in the portable application because of high energy density, low operating temperature, low fuel price and low pollutant emission. However, although there are many advantage of DMFC, commercialization of DMFCs is difficult due to poor methanol oxidation kinetics, nondurable Pt-based catalysts, expansive price and poison of Pt by formation of CO-like intermediates [1]. To overcome these problems, many studies have progressed with numerous scientists. One of the methods is to modify supports like carbon material.
Among many carbon materials such as carbon black, carbon nanotubes, graphene and carbon fiber, the graphene have unique properties which are planar structure, high surface area and outstanding mechanical and chemical properties [2, 3]. However, the Pt-graphene used in fuel cell has low electrocatalytic activity because of weak interaction between the graphene used as support and Pt particles. Recently, to overcome the low electrocatalytic activity, many efforts for modification of RGO surface have been devoted. It has been studied by considering conducting polymer, and surfactant dispersant and substitution materials of functional groups [4,5]. The key point for maximizing elelctrocatalytic acticity is dipersion, particle size and chemical composition of Pt particles.
In this study, we present Platinum (Pt) supported thiol-attached reduced graphene oxide (RGO-S). The functional groups of GO were substituted for thiol (SH), which result from strong nucleophilic substitution reaction. The sulfur (S) that has high affinity to metal combines with Pt by strong covalent bond. In conclusion, The RGO-S-Pt composite was synthesized and showed that the RGO-S-Pt composite was better than RGO-Pt composite in terms of electrocatalytic activity. Also, the electrocatalytic activity was different according to the various weight ratios of thiol. Especially, the RGO-S-Pt composite that has weight ratio of one (GO) to five (SH) presented the highest performance in terms of electrocatalytic acticity.

Acknowledgments

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning, Korea (Grant No.: NRF-2011-0009007).

References

[1] Y. Zhao, L. Zhan, J. Tian, S. Nie, Z. Ning, Electrochim. Acta, 56 (2011) 1967

[2] J.Y. Park, S. Kim, J. Electrochem. Soc., 161(4) (2014) F518.

[3] C. Song, S. Kim, J. Electrochem. Soc., 162(10) (2015) F1181.

[4] J. Debgupta and V. K. Pillai, Nanoscale, 5 (2013) 3615

[5] Q. L. Zhang, T. Q. Xu, J. Wei, J. R. Chen, A. J. Wang and J. J. Feng, Electrochim. Acta, 112 (2013) 127
Graphene Oxide Nanocomposites for Supercapacitor Electrodes
Authors: Pawar Pranav Bhagwan , Saxena Sumit , Suman Siddhartha , Shukla Shobha 
Published: February 2020

High density energy storage is one of the current demands for sustaining renewable energy systems. This requires high charging and discharging rate, large power density and stability for prolong time of service. Several materials have been explored however none of them satisfy most or all of these requirements. Graphene oxide and Poly Vinyl Alcohol based nanocomposites have recently gained attention due to high mechanical stability. We have explored the use of Graphene Oxide – Poly Vinyl Alcohol nanocomposite as electrode material for supercapacitor applications. The oxygen containing groups in Graphene oxide enables the composite to store pseudo charge making it attractive for supercapacitor applications. Nanocomposite were synthesized by mixing poly vinyl alcohol and graphene oxide in solution phase. Electrochemical characterization shows that the Graphene Oxide – Poly Vinyl Alcohol has high specific capacitance and long life cycle, further they are ecofriendly, economical and hence potential candidates to be used as electrodes in supercapacitors.
(Invited) Graphene and Graphene-Analogue Aerogels: Synthesis and Applications
Authors: Worsley Marcus A. 
Published: February 2020

Aerogels are porous solids used in a wide range of applications including sorbents, filtration, insulation, hydrogen storage, catalysis, batteries, and supercapacitors. Their unique properties are related to their high internal surface, low-density, and small pore/particle size. Two-dimensional (2D) nanomaterials, such as boron nitride and graphene, also exhibit a range of distinct optical, electronic, and mechanical properties, but are typically limited to thin films and coatings. Assembling 2D nanomaterials into monolithic aerogels expands their application space to include technologies and manufacturing processes that require a macroscopic 3D form factor. Furthermore, placing the novel intrinsic properties of 2D materials in a low-density, high surface area architecture has the potential to unlock exciting new properties and features only displayed in the aerogel system. Here, we present synthesis schemes for aerogels made from several different 2D materials, (e.g. boron nitride, graphene, dichalcogenides, etc.), including hybrid aerogels, combining two or more layered materials. Applications of these novel aerogels in applications including sorbents, sensing, energy storage, and catalysis will be covered.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
(Invited) Efficient Electrocatalysis of Oxygen Reduction with Metallo-Corroles
Authors: Elbaz Lior , Levi Naomi , Mahammed Atif , Gross Zeev 
Published: February 2020

The most active non-precious metal catalysts (NPMCs) for oxygen reduction (ORR) to date are the pyrolyzed catalysts, inspired from Heme-like complexes. These are usually composed of iron and/or cobalt coordinated by nitrogens, claimed to resemble the structure of porphyrins and phthalocynines, on the surface of a carbon support. Unfortunately, the exact structure of the catalytic sites remains a mystery and the solution for this conundrum seems be almost impossible. The advantages of using such catalysts are: (1) their high activity and (2) low price, which is derived from the cost of their precursors. The disadvantages are: (1) low durability compared to precious metal catalysts, and (2) their unknown structure, which limits their further improvement in order to obtain both the activity and durability benchmarks needed to become good alternatives for precious metals.
One of the most promising options to resolve these issues is to find non-pyrolyzed molecular non-precious metal catalysts for ORR that could be tuned to match the necessary requirements. Recently, Metallo-corroles, a relatively new family of molecular catalysts was reported to have very good potential as non-precious metal catalysts for ORR. The electro-reduction of oxygen was investigated, using a series of first row transition metal β-pyrrole-brominated 5,10,15-tris(pentafluorophenyl)-corroles [M(tpfcBr8), M=Mn, Fe, Co, Ni and Cu] as catalysts in alkaline solutions. The kinetics of the oxygen reduction reaction (ORR) on these catalysts was evaluated using the rotating disk electrode method in a solution of 0.1M KOH. These corroles were adsorbed on a high surface area carbon powder (BP2000) prior to electrochemical measurements, to create a unique composite material. The comparison between the corroles with different metal centers showed a favorable catalytic performance of the ORR in the case of Fe and Co Corroles. The mechanism by which these corroles catalyze the ORR was studied by the rotating ring disk electrode (RRDE) technique, showing that in the case of alkaline solutions, there is a favorable 4 electron transfer mechanism. When comparing the performance of these catalysts in alkaline solutions, to their performance in acidic media, it was clear that the former was substantially higher, both in the onset potentials of the ORR and in the overall kinetic parameters.
(Invited) Metal Ion Induced Cyclization of Phenoxybilinones to 5-Oxaporphyrin Metal Complexes
Authors: Mizutani Tadashi 
Published: February 2020

Linear tetrapyrroles attracted interest of chemists and biochemists, due to the interesting optical properties, and
biological importance both in photosynthesis and photoreceptor. In particular, the dynamic structural changes
of linear tetrapyrroles such as cis-trans isomerization and coordination to various metal ions are unique
features of this class of compounds. We found that 19-phenoxybilinones undergoes cyclization upon reaction with
metal ions to yield 5-oxaporphyrin metal complexes. In this paper, we summarizes the scope and limitation of
this metal-induced cyclization of 19-phenoxybilinones, and report optical properties of the metal complexes of
5-oxaporphyrin.
Solid State Rechargeable Li-Ion Batteries Prepared at Room Temperature over Flexible Organic Substrates: Performance and Limitations
Authors: El Gabaly Farid , Ware Nicholas , Fuller Elliot James , Talin Albert Alec 
Published: February 2020

Solid-state Li-ion batteries (SS-LIBs) have been widely demonstrated and represent a safer, more stable alternative to wet batteries in several applications. Specifically, thin-film SS-LIBs allow integration with microelectronics and, in general, can be prepared over a wide range of substrates and shapes such as flexible metal sheets or coaxially deposited on wires. One of the best performing chemistries for thin-film SS-LIBs, based on its energy density, long-term stability and very-low self-discharge, has a LiCoO2 cathode, LiPON solid electrolyte, and Si anode. Preparation of the efficient 'high-temperature' LiCoO2 phase typically requires substrate annealing during deposition (300-500 C) and post-annealing of the sputter-deposited films (500-800 C in oxygen) to increase crystallinity. The process is incompatible with most flexible polymer substrates and other inexpensive organic materials that cannot be heated much beyond room temperature.
Here we demonstrate solid-state thin-film Li-ion batteries based on LiCoO2/LiPON/Si chemistry over a variety of flexible organic substrates using an all-room temperature preparation. The batteries show good overall performance and have a long cycle life. We compare several metrics of performance with state-of-the-art annealed LiCoO2 batteries on silicon substrates. Finally, we explore the cases when room temperature batteries show a larger initial capacity than high-temperature LiCoO2 SS-LIBs.

Figure 1
A Novel Sulfur Cathode Architecture for High Capacity and Durable Li-S Battery
Authors: Dharmasena Ruchira , Sumanasekera Gamini U , Jasinski Jacek B , Thapa Arjun , Sunkara Mahendra Kumar 
Published: February 2020

Li-S battery technology has the potential for low cost and high capacity (up to 1470 mAh/g) battery technology for electric and stationary applications[1]. However, polysulfide creation and their dissolution in electrolytes and lack of conductivity makes it difficult to formulate sulfur cathode for Li-S battery [2-4]. Majority of the efforts to-date involved either coatings or impermeable membranes and electrolyte additives. Herein, we report the use of a mesoporous layer for Sulfur cathodes to suppress polysulfide dissolution and capacity decay in Li-S batteries.
The electrode fabricated with the meso-porous coating exhibited high and stable gravimetric discharge capacity of ~ 750 mAh/g over 100 cycles. Sulfur is supported on carbonized polyacrylonitrile (PAN) to improve the electrical conductivity in the electrode. The other part of the electrode is designed in a simple way to withstand the expansion and contraction in order to obtain higher and stable gravimetric capacity with improved cyclability. Cyclic voltammetry and impedance spectroscopy is used to understand various processes during Li alloying and de-alloying reactions within sulfur cathode. Results are compared between electrodes with and without the meso-porous coating. The fabrication procedure for our sulfur cathode is simple and scalable in terms of commercial scale manufacturing.
REFERENCES
1. Bruce, P.G., et al., Li-O2 and Li-S batteries with high energy storage. Nat Mater, 2012. 11(1): p. 19-29.
2. Singhal, R., et al., A free-standing carbon nanofiber interlayer for high-performance lithium–sulfur batteries. J. Mater. Chem. A, 2015. 3(8): p. 4530-4538.
3. Ma, X.Z., et al., S–TiO2 composite cathode materials for lithium/sulfur batteries. Journal of Electroanalytical Chemistry, 2015. 736: p. 127-131.
4. Manthiram, A., et al., Rechargeable lithium-sulfur batteries. Chem Rev, 2014. 114(23): p. 11751-87.
Lithium Sulfide Nanocrystals Synthesized By an Energy-Efficient Process for Advanced Rechargeable Batteries
Authors: Li Xuemin , Ban Chunmei , Wolden Colin , Yang Yongan 
Published: February 2020

Lithium-sulfur (Li-S) batteries are among the most promising next generation batteries to realize in the near future to meet the demands of electric vehicles and grid storage. However, the direct use of lithium anode and sulfur cathode confronts safety concerns due to the dendrite growth of lithium metal. An alternative is to use lithium sulfide (Li2S) nanomaterials. However, the commercially available Li2S exists only as micro-powders, due to the high temperature processes used in the industrial synthesis.
Herein we report a thermodynamically favorable method by taking the advantage of hydrogen sulfide (H2S), a major industrial waste gas. Considering the fact that H2S traditional abatement methods are energy intensive and cost ineffective due to the thermodynamic limitations and low values of the products sulfur and water, it is mutual beneficial to combine the alkali sulfide synthesis with the H2S abatement. The synthetic reaction developed is spontaneous and irreversible at ambient temperature and pressure, proceeding to completion very rapidly.
Specifically, lithium naphthalenide (Li-NAP) in dimethoxyethane (DME) was used to react with H2S, producing anhydrous Li2S nanocrystals, and 1,4-dihydronaphthalene, itself a value-added chemical that could be used as liquid fuel. The phase purity, morphology, and homogeneity of the resulting Li2S nanopowder was confirmed by X-ray diffraction and scanning electron microscopy. The synthesized Li2S nanoparticles (100 nm) were assembled into cathodes and their performance was compared to cathodes fabricated using commercial Li2S micropowders (1 - 5 µm). Electrochemical analyses demonstrated that the synthesized Li2S nanoparticles were superior in terms of (dis)charge capacity, cycling stability, output voltage, and voltage efficiency.
Electrochemistry in the Next Generation of Rechargeable Batteries: Challenging the Maze with Multiscale Computational Modeling
Authors: Franco Alejandro A. , Yin Yinghui , Thangavel Vigneshwaran , Quiroga Matias , Morcrette Mathieu 
Published: February 2020

The development of the next generation of rechargeable batteries and their consequent market penetration, require a rational guide for the optimization of the balance between the intrinsic capacity of the used storage materials, their statistical utilization in the composite electrodes and the macroscopic cell design.
Computational multiscale modeling emerges nowadays as a powerful tool for building such a rational guide through the in silico representation of complex processes involving electrochemistry and species transport in operando conditions [1-3].
In this contribution we discuss our most recent progresses on the development of a novel integrative multiscale modeling platform devoted to understand the impact of the electrodes mesostructure on the electrochemical response of rechargeable batteries. The platform is supported on a combination of deterministic (continuum) and stochastic (Kinetic Monte Carlo) models resolving detailed electrochemistry and reactants/charge transport [4-6]. It allows capturing, with three-dimensional resolution, the impact of properties such as active material particles percolation, pore size distributions and pores interconnectivity, on the discharge cell performance (Figure). The flexibility of the approach is illustrated here through the investigation of hierarchical carbons as positive host electrode material in lithium-sulfur [7] and lithium-O2 batteries. In general, simulations reveal heterogeneities on the spatial location of electrochemical activity and nucleation centers with a strong dependence on the carbon mesostructural properties. Specific similarities and differencies between the two illustrated applications are discussed and possible ways for optimizing the electrodes performance are suggested.
[1] Physical Multiscale Modeling and Numerical Simulation of Electrochemical Devices for Energy Conversion and Storage: From Theory to Engineering to Practice. A.A. Franco, M.L. Doublet, W.G. Bessler (Eds.), Springer (2015).
[2] A.A. Franco, RSC Advances, 3 (32) (2013) 13027.
[3] A.A. Franco (Ed.), Rechargeable Lithium Batteries: From Fundamentals to Applications, Woodhead/Elsevier Science (2015).
[4] G. Blanquer, Y. Yin, M.A. Quiroga, A.A. Franco, J. Electrochem. Soc., 163 (3) (2016) A329.
[5] K. H. Xue, E. McTurk, L. Johnson, P.G. Bruce, A.A. Franco, J. Electrochem. Soc., 162 (4) (2015) A614.
[6] M. Quiroga, K.H. Xue, T.K. Nguyen, H. Huang, M. Tulodziecki, A.A. Franco, J. Electrochem. Soc., 161(8) (2014) E3302.
[7] K.H. Xue, V. Thangavel, Y. Mammeri, M.A. Quiroga, C. Guery, P. Johansson, M. Morcrette, A.A. Franco, in preparation (2015).

Figure 1
Influence of Electrolyte Solvent Properties on Li-O2 Battery Discharge Product Morphology
Authors: Zakharchenko Tatiana Konstantinovna , Itkis Daniil Mikhailovich 
Published: February 2020

Li-air batteries (LAB) can theoretically enable energy storage with 5-fold increased specific energy in comparison to that of Li-ion systems. A number of fundamental problems prevent LAB from being reversibly rechargeable however. Precipitation of the discharge products, e.g. lithium peroxide (Li2O2), inside a positive electrode is one of the key processes that control battery performance [1], thus detailed understanding of product deposition mechanisms is required to achieve deeper discharge and complete reversibility.
Product formation is a result of multistep chemical process ending up with crystallization. Depending on the discharge conditions and, especially, electrolyte solvent, different growth mechanisms occur giving rise to quite different morphologies. Recently, it has been reported that solvent’s donor number play a key role in lithium peroxide formation processes [2]. Here we test the proposed theory in a wider range of solvents, including DMA and sulfolane.
Carbon paper was used as an electrode material with controlled porosity. Solvent list included DMSO, MeCN, DMA, DME and sulfolane and was demonstrated to be relatively stable to ORR products and intermediates. Composition, structure and morphology of the discharge products formed during potentiostatic discharge were analysed.
It was shown that oxygen reduction in the presence of lithium ions in the electrolyte proceeds with the formation of plate-like particles Li2O2 that form a film or agglomerate complex morphology. The formation of Li2O2 crystalline plates proceeds via superoxide disproportionation in solution [3].
[1] Christensen J, Albertus P, Sanchez-Carrera RS et al. A Critical Review of Li-Air Batteries// J. Electrochem. Soc. 2012, 159:R1.
[2] Johnson L, Li C, Liu Z et al. The role of LiO2 solubility in O2 reduction in aprotic solvents and its consequences for Li–O2batteries// Nature Chem. 2014, 6:1091–1099.
[3] T.K. Zakharchenko, A. Y. Kozmenkova, D.M. Itkis et al. Lithium peroxide crystal clusters as a natural growth feature of discharge product in Li-O2 cell// Beilstein J. Nanotechnol., 2013:4.
Enhanced Electrochemical Reversibility of Li-Rich Layered Li2MO3 Cathodes: Understanding Aliovalent Co3+ Substitution with Excess Lithium
Authors: Arunkumar Paulraj , Im Won Bin 
Published: February 2020

Li-rich layered materials are the promising high capacity cathode with superior energy density for the next-generation Li-ion batteries. The existence of excess lithium in these cathodes resulted in the high discharge capacity (>250 mAh g-1) with excellent structural and electrochemical stability. However, several challenges that hinder their application are poor rate capability and electrochemical Li irreversibility due to O2 loss in the first charging cycle and undesired phase transformation during cycling.[1]
Extensive efforts has been made to improve the Li reversibility, employing aliovalent metal doping in the Li2
MO3 component due to an enhanced structural stability and improved electronic conductivity.[2, 3] In a step further, an intentional inclusion of excess lithium as a charge compensation in the aliovalent doped Li2
MO3 cathodes were least investigated.
Herein, we report Li2+x
Ru1-x
Co
x
O3 (x = 0, 0.1, 0.2, and 0.5) cathode with an enhanced electrochemical Li reversibility at high C rate. The structural and electrochemical properties were investigated by X-ray diffraction, solid-state NMR, X-ray photoelectron spectroscopy, galvanostatic cycling, and cyclic voltammetry to understand the enhancement in the Li reversibility and rate capability of the cathode. High-performance Li2.1Ru0.9Co0.1O3 cathode delivered an initial capacity of 250 mAh g−1 and enhanced Li+ extraction of 1.00 mol (78 % capacity retention) after 50 cycles at 1C compared to 0.48 mol of Li+ extraction in the pristine Li2RuO3. Low Co3+ content could realize an enhanced reversible Li+ extraction originating from the cation ordering, facile charge transfer, and improved reversible anion-redox chemistry. The origin of the enhanced Li reversibility on the structural and electrochemical properties of cathodes were investigated.

References

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15 (2005) 2257-2267.

M. Sathiya, K. Ramesha, G. Rousse, D. Foix, D. Gonbeau, A.S. Prakash, M.L. Doublet, K. Hemalatha, J.M. Tarascon, Chem. Mater.,
25 (2013) 1121-1131.

M. Sathiya, G. Rousse, K. Ramesha, C.P. Laisa, H. Vezin, M.T. Sougrati, M.L. Doublet, D. Foix, D. Gonbeau, W. Walker, A.S. Prakash, M. Ben Hassine, L. Dupont, J.M. Tarascon, Nat. Mater.,
12 (2013) 827-835.

Figure 1