bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lithium Polysulfide Flow Batteries Enabled By Percolating Nanoscale Conductor Networks
Authors: Chiang Yet-Ming , Fan Frank , Woodford William , Li Zheng , Baram Nir , Smith Kyle C. , Helal Ahmed , McKinley Gareth , Carter W. Craig 
Published: February 2020

The high solubility of lithium polysulfides in nonaqueous electrolytes and associated loss mechanisms have long been a barrier to the development of Li-S batteries. The same attribute allows lithium polysulfide solutions to be used in a flow battery architecture, where the high cell voltage and redox-active species concentrations (>2M) compared to conventional aqueous flow batteries provides significantly higher energy density and potentially lower cost (<$100/kWh at system level). Here we demonstrate a new design approach wherein diffusion-limited aggregation of nanoscale conductor particles at ~1 vol% concentration is used to impart mixed electronic-ionic conductivity to redox-active solutions, forming flow electrodes with embedded current collector networks that self-heal after shear. As illustrated in Fig. 1, flow cells of this architecture can distribute electrochemical activity throughout the volume of flow electrodes rather than being confined to surfaces of stationary current collectors. Applying this concept to lithium polysulfide semi-flow batteries, we demonstrate that the nanoscale network architecture enables cycling of polysulfide solutions deep into precipitation regimes that otherwise show poor capacity utilization and reversibility. Figure 2 compares results for identical 2.5 mol S/L solutions (as Li2S8 in TEGDME with 1 wt% LiNO3 and 0.5M LiTFSI) tested in half-cells using a conventional fibrous carbon current collector, and using the nanoscale conductor network approach without the current collector. At C/4 rate, the latter exhibits specific capacity of 1200 mAh g-1 (vs. theoretical capacity of 1460 mAh g-1 for this solution), about a factor of 5 greater than with the carbon fiber current collector.
Lithium polysulfide half-flow cells are demonstrated for the first time, operating in two modes: 1) Potentiostatic cycling under continuous flow (the typical configuration for flow batteries), in which at C/10-C/15 rates reversible capacity is ~380 mAh g-1 and catholyte energy density is ~60 Wh/L (with respect to Li/Li+), and 2) Galvanostatic cycling with intermittent flow (in which fluid is pumped in discrete volumes with complete charging or discharging of the electroactive region in between), in which reversible capacities are ~650 mAh g-1 and catholyte energy density is ~100 Wh/L. An example of potentiostatic cycling results appears in Figure 3; the performance of such devices from fundamental Li-S reaction kinetics to non-Newtonian rheology to electrochemical cell design will be discussed.

This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.
Lithium Metal Polymer Battery Interfaces Studied By Hard X-Ray Microtomography
Authors: Devaux Didier , Harry Katherine J. , Parkinson Dilworth Y. , Yuan Rodger , Hallinan Daniel T. , MacDowell Alastair A. , Balsara Nitash P. 
Published: February 2020

Conventional Lithium-ion batteries contain volatile liquid compounds that can leak and violently react with the environment leading to a fire.1 Solid polymer electrolytes (SPEs) are one solution as these flexible materials do not contain any volatile components. Additionally, they enable the use of high energy density lithium (Li) metal anodes.2 However, Li metal battery utilization is hampered by the dendrite growth.3 Upon cycling lithium metal is plated unevenly on the lithium metal anode side. Such dendrites can grow through the electrolyte and cause the battery to fail by short circuit.
Solid block copolymer electrolytes are a class of SPEs that contains a mechanical reinforced block and an ion conducting block doped with a Li salt.4 The block immiscibility induces microphase separation, producing ordered morphologies on the nanometer scale.5 The seminal work done by K.J. Harry et al.
6 on solid polystyrene-b-poly(ethylene oxide) (SEO) block copolymer electrolyte led to a better understanding of Li dendrite formation and growth. Using Li symmetric cells dendrite evolution was observed and imaged by a non-destructive tool, hard X-ray microtomography.
To go toward the application, batteries were imaged by hard X-ray microtomography. The batteries are made of a Li metal anode, a SEO electrolyte layer and a composite cathode. The cathode deposited onto on Aluminum (Al) foil, contains LiFePO4 as active material, SEO electrolyte as binder, and carbon black. Hard X-ray microtomography enables to visualize the microstructural changes at the Li/SEO and SEO/cathode interfaces to get insight on the battery failure mechanisms.
The batteries were cycled at 90°C at a C/20 charge rate and a C/8 discharge rate (Figure 1a). Prior and after battery cycling, the electrode-electrolyte interfaces were imaged by hard X-ray microtomography as shown in figure 1b and 1c, respectively. We found that the supposed intimate Li/SEO interface undergoes a strong delamination phenomenon that leads to the formation of voids (Figure 1b). Using a rendering image software, the void fraction can be measured all along the Li/SEO interfaces, and its effect on the battery capacity fading be estimated.

References

J.-M. Tarascon, M. Armand, Nature, 414 (2001) 359.

M. Armand, J.-M. Tarascon, Nature, 451 (2008) 652.

M. Rosso, C. Brissot, A. Teyssot, M. Dollé, L. Sannier, J.-M. Tarascon, R. Bouchet, S. Lascaud, Electrochimica Acta, 51 (2006) 5334.

M. Singh, O. Odusanya, G.M. Wilmes, H.B. Eitouni, E.D. Gomez, A.J. Patel, V.L. Chen, M.J. Park, P. Fragouli, H. Iatrou, N. Hadjichristidis, D. Cookson, N.P. Balsara, Macromolecules, 40 (2007) 4578.

V. Abetz, T. Goldacker, Macromolecular Rapid Communications, 21 (2000) 16.

K.J. Harry, D.T. Hallinan, D.Y. Parkinson, A.A. MacDowell, N.P. Balsara, Nature Materials, 13 (2014) 69.

Figure 1
Subphthalocyanines: Supramolecular Organization and Self-Assembling Properties
Authors: Torres Tomas , Guilleme Julia , González-Rodríguez David , Sánchez-Molina Irene , Claessens Christian G , Zango German , Martínez-Díaz M. Victoria , Guzman David , Vazquez Purificacion , Koji Naoda , Rodriguez-Morgade M. Salome , Trukhina Olga 
Published: February 2020

Subphthalocyanines (SubPcs), phthalocyanine analogues, are intriguing compounds made of three diiminoisoindoline units N-fused around a boron atom. Their 14 pi-electron aromatic core associated with their curved structures render them appealing building blocks for the construction of multicomponent photo- or electroactive assemblies. Recently, the development of an improved synthetic methodology for axially substituted SubPc allowed the efficient synthesis of a variety of SubPc-based hybrids.
To enhance the understanding of the nature of these curve pi-extended surfaces, we have undertaken a series of studies, including the synthesis and characterization of subphthalocyanine-based capsules. These supramolecular systems have been successfully been employed for the encapsulation of fullerenes. Furthermore, it was possible to evaluate the binding constants of the host-guest complexes. Finally, a full study of the photophysical properties revealed that the subphthalocyanines can undergo an energy transfer transduction of singlet excited state energy to the fullerene inside the cavity upon photoexcitation.
SubPc pi-systems can be organized at supramolecular level. Thus, the self-assembly of axial dipolar subphthalocyanine molecules in the presence of electric fields leads to uniaxially oriented columnar liquid crystalline materials that exhibit permanent polarization.
References

Sánchez-Molina, I.; Grimm, B.; Claessens, C. G.; Krick-Calderón, R.; Guldi, D. M.; Torres, T. J. Am.
Chem. Soc. 2013, 135, 10503-10511.

Sánchez-Molina, I.; Claessens, C. G.; Grimm, B.; Guldi, D. M.; Torres, T. Chem. Sci.
2013, 4, 1338-1344

Claessens, C. G.; Gonzalez-Rodriguez, D.; Rodríguez-Morgade, M. S.; Medina, A.; Torres, T. Chem. Rev., 2014, 114, 2192−2277.
ORR Catalyst Based on Polypyrrole Nanowires with Electrochemically Immobilized Macrocycles
Authors: Sansiñena José-María , Chlistunoff Jerzy 
Published: February 2020

Optimizing the amount of platinum, and eventually avoiding its use, is one of the ultimate goals for polymer electrolyte fuel cells (PEFC). In this regard, different approaches have been investigated such as using platinum alloys with non-precious metals, preparing particles with a non-precious metal core and a platinum shell, and by the use of novel supporting materials [1-3].
As part of the latter effort, carbon has been the most widely used electronically conducting support to obtain higher active surface area and efficiency. In addition, nanostructured conducting materials like carbon nanotubes, nanofibers and mesoporous carbon have also been used for supported metal catalysts [4-7].
The work we are presenting involves the development of a new class of ORR catalysts based on polypyrrole nanowires with immobilized macrocycles, which are incorporated into the polymer during the electropolymerization process as counterions. In this new approach polypyrrole nanowires play the role of a conductive supporting material while the incorporated macrocycles provide the active centers for ORR catalysis (Figure 1).
Electrochemical characterization, including RRDE studies, was performed to determine the catalytic properties of the new conductive nanostructured material. For this purpose, the catalyst was electrochemically deposited on a glassy carbon disk electrode in presence of the macrocycles as supporting electrolyte in order to incorporated them into the polymer as counterions.
Conclusions

The new ORR catalyst based on polypyrrole nanowires with immobilized macrocycles showed promising RRDE results for ORR catalysis. Furthermore, this catalyst demonstrated good potential as a new class of non-precious metal catalyst without involving pyrolysis steps during the preparation process.

Acknowledgement

The financial support from the University of California (grant 12-LR-237440) is gratefully acknowledged.
References

P.H. Matter, E.J. Biddinger, U.S. Ozkan, in Catalysis Book Series, Spivey. J., Editor, Royal Society of Chemistry, 20, 338-361, Cambridge, (2007).

Mark K. Debe, Alison K. Schmoeckel, George D. Vernstrom, Radoslav Atanasoski, J. Power Sources, 161, 1002–1011 (2006).

W.S. Shi, P. Liang, D. Ge, J. Wang, Q. Zhang, Chem. Commun., 2414–2416 (2007).

H. Zhao, L. Li, Jun Yang, Y. Zhang, Journal of Power Sources, 184, 375–380 (2008)

R. Dersch, M. Steinhart, U. Boudriot, A. Greiner, J. H. Wendorff, Polym. Adv. Technol., 16, 276–282 (2005).

T. Ochi, Biochem. Biophysic. Res. Commun., 11, 67–70 (2004).

G. G. Wallace, P.C. Innis, J. Nanosci. Nanotechnol., 2, 441–451 (2002)

Figure 1. SEM picture of the new class of ORR catalysts based on polypyrrole nanowires with immobilized macrocycles with ORR catalysis centers.

Figure 1
Heme Ruffling in Cytochrome c As a Mechanism to Control Electron Transfer
Authors: Champion Paul M 
Published: February 2020

Recent studies of a variety of heme protein systems demonstrate that impulsively driven Raman vibrational coherence (or vibrational coherence spectroscopy) is a sensitive probe of thermally accessible and functionally relevant distortions of the active site heme chromophore. The observed signals involve otherwise symmetry forbidden optically driven coherent motions that become allowed due to protein-induced distortions of the heme along its out-of-plane normal modes. The low frequency (ℏω < kBT~300K~200 cm-1) of such modes allow the efficient extraction of energy from the thermal bath so that it can be utilized it for barrier crossing. An example of such a situation is the heme doming motion, which is a key reaction coordinate for ligand binding. Generally, the low frequency out-of-plane modes of the heme are prime candidates to serve as biochemical reaction coordinates. The mixing with other delocalized low-frequency modes of the protein, or with binding partners, offers a potential control mechanism.
In order to probe the effect of heme “ruffling” on electron transport, we studied three cytochromes that display a wide variation in the protein-induced distortion along this mode1. As the ruffling distortion is increased, the ruffling mode frequency decreases from ~ 60 cm-1 to ~ 45 cm-1. The photoreduction cross-section is also measured and found to decrease exponentially as a function of the magnitude of the distortion. Given the similarity in the distance between the heme and the nearest aromatic amino acid for all three proteins, the order-of-magnitude changes in photoreduction rate demonstrate that the ruffling coordinate can serve as a control mechanism for electron transport in heme proteins. For example, major differences in heme ruffling are noted for cytochrome c when bound to the mitochondrial membrane compared to its solution structure.
1. Y. Sun, A. Benabbas, W. Zeng, J. Kleingardner, K. Bren, and P. M. Champion, Proc. Natl. Acad. Sci.(USA) 111, 6570-6575 (2014).
The Molecular Approach for Artificial Photosynthesis
Authors: Aukauloo Ally , Sircoglou Marie , Herrero Christian , Leibl Winfried , Quaranta Annamaria , Cherdo Stephanie , ElGhachtouli Sanae 
Published: February 2020

Nature has provided us with the main clues how to use solar energy to power multielectronic catalytic reactions leading to its storage in form of chemical bonds. A key feature is that nature uses molecular metal complexes based on earth abundant metal ions at the active catalytic sites of most enzymes participating in the main energetic transduction pathways. Therefore, replicating these activities using synthetic molecular complexes is a central research theme. Photosystem II, the enzyme responsible for the water oxidation can be conceptualised as being made up of two parts: a photoactive unit and a catalytic module held at optimised distances through the protein matrix. We are involved in the design of modular assemblies of photoactive units and molecular based catalytic unit for the photoactivation of water. We will discuss on our work to use Click chemistry to develop a library of modular ensembles for the study of light induced electron transfer and our effort in the understanding of water activation in the oxygen atom transfer reactions. We will also present our latest results in the field of molecular catalyst for the production of H2.
Synthesis of Biologically Relevant Compounds Catalyzed By Metal Porphyrin Complexes
Authors: Gallo Emma , Zardi Paolo , Carminati Daniela Maria , Tseberlidis Giorgio 
Published: February 2020

The direct amination of hydrocarbons is a reaction of great synthetic interest because of the biological and pharmaceutical relevance of aza-derivatives. For several years we have studied the formation of C-N bonds using aryl azides (ArN3)1 as nitrogen sources and metal porphyrins as catalysts. Amongst all the metal porphyrin catalysts,2 ruthenium porphyrins show a good catalytic activity in both inter- and intramolecular transfer of a nitrene functionality “ArN” from aryl azides into C-H bonds. The sustainability of the synthetic procedure is related to the high atom efficiency of azides which insert the aza-fragment into the organic skeleton with the formation of benign molecular nitrogen as the only stoichiometric side product.
Herein we report the use of ruthenium porphyrins to promote the synthesis of biologically interesting compounds such us: a)

α-

and β

-

amino ester
by amination of benzylic C−H bonds. The methodology was also effective in synthesizing two derivatives of methyl L-3-phenyllactate in order to convert one of them into the corresponding β-lactam;3
b) dihydrophenanthridines and phenanthridines
, important core structures in a large class of pharmaceutical compounds, through the intramolecular amination of several 2-azido biaryls;4
c) C3-functionalized indoles
by an intermolecular reaction of aryl azides with alkynes. Several derivatives were synthesized with yields up to 95%, high regioselectivity, and without requiring the time consuming prefunctionalization of reagents and the addition of oxidants and/or additives.5

In addition, we describe the catalytic activity of glicoporphyrin derivatives in amination reactions. It is worth noting that the use of these catalytic materials with very low toxicity could enhance the eco-sustainability of the entire synthetic process.

References:

[1] a) S. Cenini, E. Gallo, A. Caselli, F. Ragaini, S. Fantauzzi, C. Piangiolino Coord. Chem. Rev.
2006, 250, 1234; b) D. Intrieri, P. Zardi, A. Caselli, E. Gallo Chem. Commun., 2014, 50, 11440. [2] S. Fantauzzi, A. Caselli, E. Gallo Dalton Trans, 2009, 5434. [3] P. Zardi, A. Caselli, P. Macchi, F. Ferretti, E. Gallo Organometallics
2014, 33, 2210. [4] D. Intrieri, M. Mariani, A. Caselli, F. Ragaini, E. Gallo Chem. Eur. J.
2012, 18, 10487. [5] P. Zardi, A. Savoldelli, D. M. Carminati, A. Caselli, F. Ragaini, E. Gallo ACS Catal.
2014, 4, 3820.

Figure 1
Corrosion Monitoring of Reinforcing Steel in Concrete By Electrochemical Impedance Spectroscopy
Authors: Hoshi Yoshinao , Soukura Masanori , Shitanda Isao , Itagaki Masayuki , Kato Yoshitaka 
Published: February 2020

The corrosion of the reinforcing steel in concrete is strongly related to the loss of cover concrete and the steel bar diameter. These effects may cause sudden failure of a structure. Therefore, it is important to obtain the corrosion rate of the reinforcing steel in concrete precisely.
An electrochemical impedance spectroscopy (EIS) is the powerful method for evaluating the conditions of the reinforcing steel because the EIS enables us to discriminate the time constants of elementary steps in the dissolution process without causing damage to the electrodes. We applied the EIS to monitor the corrosion rate of the reinforcing steel in concrete. In order to establish the method of the corrosion monitoring by EIS, the effects of the covering depth and the concentration of chloride ions on the corrosion of the reinforcing steel in concrete were investigated. All reinforcing steels were cast using a concrete. The covering depth of the concrete is 10, 20 or 30 mm. The water-cement (W/C) ratio of the concrete is 40, 50 or 60. A NaCl was used as the source of the chloride ions. Impedance measurements were performed by a two-electrode system using potentiostat (Solartron, 1287) and a frequency response analyzer (FRA) (Solartron, 1255B) combined with oscilloscope (IWATSU, SS-7802). The working electrode and the counter electrode were the reinforcing steel. The impedance spectra were measured in the frequency range from 10 mHz to 1 MHz at 5 frequencies per decade with AC amplitude of 10 mV. The impedance spectra of the reinforcing steels in concrete with different covering depth and concentrations of chloride ions were discussed.
Different Vanadium Compounds Ash Corrosion of Boilers Using Heavy Fuel Oil
Authors: Montero Xabier , Galetz Mathias C 
Published: February 2020

Vanadate induced or accelerated corrosion is observed in fossil energy conversion systems. The combustion of poor quality fuel oils with high asphaltene mounts and other vanadium and sulfur rich-compounds produces ash deposits on components such as heat exchangers, boilers or turbine blades and vanes. Boiler steel tubes are reported to be highly sensitive to this kind of high temperature corrosion enhanced by liquid phase fuel oil ash deposits.
The mechanisms of hot corrosion by molten sulfate-vanadate deposits were investigated for low and medium chromium steels as well as aluminide coated steels with different ash deposits containing CaSO4, Ca3(PO4)2, NaCl, Na2O and Na2S04 their combinations with V205. All samples were exposed to the ash deposits at 600°C in laboratory air. The deposits and the exposed surfaces were characterized by XRD, SEM and EPMA.
High-Temperature Corrosion Characteristics of Nano-Structured Coatings in Secondary System of Nuclear Power Plants
Authors: Kim Seung Hyun , Kim Jeong Won , Kim Ji Hyun 
Published: February 2020

Flow-accelerated corrosion (FAC) of carbon steel pipe systems in secondary system of nuclear power plants is one of the materials degradation issue in nuclear industry. In this study, the feasibility of nano-structured coating application based on electroless nickel plating and high-velocity oxy-fuel (HVOF) is investigated in order to reduce or mitigate the FAC of carbon steel pipes in the secondary system of nuclear power plants. While nano-structured coatings generally show higher corrosion resistance and mechanical properties compared to traditional coating techniques and additionally with low surface roughness, their corrosion characteristics in high temperature water were not evaluated fully enough. In this study, therefore, their corrosion characteristics in ammonia and mono ethanol amine (ETA) electrolyte at room temperature as well as high temperature are firstly evaluated by potentiodynamic polarization measurement and electrochemical impedance spectroscopy. From this study, it is observed that the metal loss of coated carbon steels are drastically decreased compared to as-polished carbon steels.
Polymer Supported and Freestanding Transparent Electrodes Produced By Ink-Jet Printing and Electrodeposition
Authors: Oriani Andrea Vittorio , Spreafico Marco Alberto , Cojocaru Paula , Marrani Alessio , Triulzi Francesco , Apostolo Marco , Magagnin Luca 
Published: February 2020

Transparent conductive electrodes play an important role in different applications, as thin-film solar cells, flat-panel displays and light emitting diodes1-3. With the increasing demand arising from flexible devices, mechanical properties of electrodes are becoming more and more important and alternatives to traditional materials are being investigated4,5. Doped metal oxides, e.g. ITO, are mostly used at the moment, but their main limitation derives from their ceramic nature that makes them brittle and therefore prone to cracking, when deposited on flexible substrates6. We studied the production of metallic micronets, with the aim of finding an alternative to ITO for transparent conductive electrodes. The use of metals, which are the materials owning the highest performances in terms of electrical conductivity, allows maintaining the desired level of transparency of the electrode, given by the optimization of the geometrical parameters of the micro-net. Both polymer supported and free standing metallic micronets were produced. To obtain the former structure, a conductive Ag pattern was printed on PET substrate using ink-jet printing (an example is shown in Figure 1), and then a copper layer can be grown by electrodeposition on the silver printed lines, to obtain the freestanding structure. Release of the metallic micro-net from the PET substrate is spontaneously obtained during the electrodeposition step. Electrical and optical properties of the produced electrodes were investigated. The free-standing metallic micro-net has resistivity two orders of magnitude lower than a commercially available sample of ITO-coated PET, while maintaining high transparency.
Figure 1: SEM image of Ag pattern printed on PET substrate
References
1. S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer and K. Leo, Nat. Lett., 459, 234 (2009).
2. A. C. Arias, J. D. MacKenzie, I. McCulloch, J. Rivnay and A. Salleo, Chem. Rev., 110, 3 (2010).
3. J. J. Shiang, Interface, 18, 37 (2009).
4. H. Chang et al., Adv. Funct. Mater., 20, 2893 (2010)
5. L. Hu et al., ACS Nano, 4, 2955 (2010)
6. Z. Chen, Thin Solid Films, 394, 201 (2001)

Figure 1