bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbon-Free Connected Ru, Ir Based Nanoparticle Catalysts for Polymer-Electrolyte Water Electrolysis
Authors: Sugita Yoshiyuki , Tamaki Takanori , Kuroki Hidenori , Yamaguchi Takeo 
Published: February 2020

Oxygen evolution reaction (OER) catalysts for polymer-electrolyte water electrolysis (PEWE) suffered from their low surface area because carbon support cannot be used for OER operating at high potential. Connecting metal nanoparticles enable catalysts to conduct electrons through nanoparticle networks without any support materials while keeping their high surface area. Thus, connected nanoparticle catalysts (Fig. 1 (A)) are promising for OER. Previously, we have developed connected Pt-Fe nanoparticle catalysts with hollow capsule structure for oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs).[1]

In this study, we proposed Ru and Ir nanoparticle catalysts for OER in water electrolysis because Ru and Ir have high OER activity. Ru and Ir nanoparticle catalysts were synthesized as follows. First, Ru and Ir nanoparticles were synthesized on silica template (PDDA/SiO2) via polyol method using tetraethylene glycol as reducing agent and Ru(III) acetylacetonate or Ir(III) acetylacetonate as the metallic precursors (M/PDDA/SiO2, M is Ru or Ir). Then, these nanoparticles were treated in supercritical ethanol at 330ºC for 90 min (Ru) or 60 min (Ir) (sc-M/SiO2). Dissolution of SiO2 in 3 M NaOH solution at 85ºC for 3 h made porous hollow structure (M capsule). OER performance were evaluated by electrochemical measurement in 0.1 M HClO4 solution.
Fig. 1 (B) shows TEM image of Ir capsule. Capsule and networks structure of each catalysts were observed by TEM images. All Ru catalysts inactivated for OER at the first CV cycle. OER activity of Ru/PDDA/SiO2 did not improve by heat oxidation treatment in air at 400ºC. Fig. 1 (C) shows OER curves of Ir catalysts. All Ir catalysts showed stable OER. Among them, Ir/PDDA/SiO2 had the highest OER activity. Mass activity at 1.48 V of Ir/PDDA/SiO2 was higher than RuO2
[2], IrO2
[2] and Ir/C­[3] in previous reports as shown in Fig.1 (D). Heat treatment of Ir/PDDA/SiO2 at 200ºC further improved.
In conclusion, we successfully synthesized connected Ru and Ir nanoparticle catalysts. Among them, Ir/PDDA/SiO2 showed the highest OER activity and the activity was further improved by heat oxidation treatment. The results showed that connected Ir nanoparticle catalysts are promising as carbon-free catalysts for water electrolysis.
[1] T. Tamaki, H. Kuroki, T. Yamaguchi et al., Energy Environ. Sci., 8, 3545-3549 (2015).
[2] Y. Lee et al., J. Phys. Chem. Lett., 3, 399-404 (2012).
[3] HN. Nong et al., Chem. Sci., 5, 2955-2963 (2014).

Figure 1
Plasmonic Cu Nanoparticles Prepared By DC Magnetron Sputtering
Authors: Gustavsen Kim R , Wang Kaiying 
Published: February 2020

Noble metal nanostructures are known for their unique optical property as localized surface plasmon resonance (LSPR), which electromagnetic radiation interacts with the free electrons of the metallic nanostructure, resulting in collective oscillations and thus to a significant strengthening of the local electric field surrounding the particles [1]. Although noble metal such as Ag and Au have been widely known for their plasmonic properties, Cu has often been overlooked due to surface oxidation problems, which significantly reduces the excitation intensity [2]. We present in this paper a systematic study of Cu nanoparticles assembled by direct current (DC) magnetron sputtering on quartz substrates. The effect of deposition time on the optical properties, particle size, and particle spacing has been investigated.
The Cu nanoparticles were deposited in Argon atmosphere with a pressure of 19 mTorr, DC power of 200W, and a substrate temperature of 400°C. Additionally, the Cu nanoparticles were annealed at 400°C in vacuum for 6 hours following deposition. A photograph of the Cu nanoparticles on quartz is seen in Figure 1. From left to right, the color of the samples changes from dark blue with a green hue to a light blue color as the deposition time decreases. Absorbance spectra (250-850 nm) in Figure 2 show that increased deposition time lead to higher absorbance and a slight red shift of the LSPR peak. SEM images indicated that particle size for the individual samples was not uniform, which is seen in Figure 3 (particle size ~8 – 28 nm).
In conclusion, we have demonstrated the fabrication of Cu nanoparticles by DC magnetron sputtering. The particle sizes ranged from ~8 – 28 nm when depositing for 45 seconds. Particle size, geometry, height, and spacing, which are directly responsible for the optical response, are to be investigated on quartz substrates using scanning electron microscope (SEM) and atomic force microscope (AFM).

References

Christy L. Haynes and Richard P. Van Duyne* The Journal of Physical Chemistry B
2001
105 (24), 5599-5611 DOI: 10.1021/jp010657m

George H. Chan,Jing Zhao,Erin M. Hicks,George C. Schatz,* and, and Richard P. Van Duyne* Nano Letters
2007
7 (7), 1947-1952 DOI: 10.1021/nl070648a

Figure 1
Electronic Structures of a Cerasome Surface Model
Authors: Oda Masato 
Published: February 2020

Drug therapy is always accompanied by undesirable side effects, because the drug spread out and affect to healthy tissues and organs as well. One of the ways to reduce the side effects is to develop a system that deliver a desired amount of the drug to a diseased part directly. The system is known as drug delivery system (DDS). The construction of the DDS requires the technology to encapsulate the drug and release it around the diseased part. Lipid bilayer vesicles, so-called liposomes, are typical DDS materials. However, liposomes are not very stable because all the lipids are connected via van der Waals interactions. As a result of this low stability, sometimes liposomes cannot reach the diseased part intact. There is a pressing need to develop more stable liposomes capable of encapsulating the drug. Recently, erasomes, i.e., liposomes featuring surfaces reinforced with a siloxane bond network, have been developed. It has been shown that a cerasome can encapsulate the drug and is much more stable than liposomes. Thus, cerasomes are promising materials for DDS. However, the improvement in stability is accompanied by a difficulty in opening the capsule. Breaking the chemical bonds of a cerasome surface requires information about its microstructure and electronic states, although the microscopic properties of cerasomes remain unclear.
In the previous work, we construct a simple cerasome model (figure) to investigate the electronic structures of its surface. Comparing the electronic structures of the membrane model with that of the molecule, we reveal that there are mid-gap states in the membrane model that are not in the molecule. These mid-gap states consist of antibonding states of Si-C bonds that connect the siloxane network and organic parts of the lipid. The existence of the antibonding states in the gap indicates that there is a possibility to break cerasomes with some electronic excitations to the system. However, the previous model is extremely simple, we assume perfect siloxane network, although there are many O- and OH groups on the surface of actual cerasomes. The purpose of this study is to investigate effects of surface substituent groups on the electronic structures of the cerasome model.
We introduce some O- and OH groups in the surface of the model and calculate the electronic strucutres. All calculations are carried out using first-principles scheme based on density functional theory. It is revealed that the energy of the mid-gap states is modulated around 0.2 eV, but still in the HOMO-LUMO gap of the lipids. This result indicates that we can expect that the mid-gap states valid for the realistic cerasomes.

Figure 1
Ion Dynamics in Al-Doped Cubic Li7La3Zr2O12 Garnet-Type Single Crystals
Authors: Posch Patrick , Lunghammer Sarah , Berendts Stefan , Uecker Reinhard , Rettenwander Daniel , Wilkening Martin 
Published: February 2020

Li7La3Zr2O12 (LLZO) garnet-type materials are regarded as promising candidates for solid electrolytes and have been extensively investigated in the past few years.[1,2] Several studies report on an increase in conductivity by doping with ions to stabilize the cubic structure.[3,4] In the present study we focus on the ionic transport processes in Al-doped LLZO single crystals. To investigate ionic motions we used 7Li nuclear magnetic resonance (NMR) spectroscopy and impedance spectroscopy. With the help of rotating-frame spin-lock NMR spin-lattice relaxation (SLR) we looked at localized and medium-ranged ionic motions, respectively. Impedance spectroscopy was used to shed light on the long range ion dynamics. At room temperature the total conductivity turned out to be 0.082 mS cm-
1 at, which is remarkably good for LLZO with an Al-content of only 0.34 wt%.[5]

Most importantly, 7Li NMR spin-lock NMR of revealed two overlapping diffusion-induced processes that share almost the same activation energy. A similar behavior has recently been seen for Mo-bearing LLZO.[6] Overall, activation energies gathered from spin-lock NMR and impedance measurements are in good agreement with each other; both techniques yield values around 0.36 eV. The solid-state coefficient (D) and the self-diffusion coefficient (Dsd), calculated from impedance spectroscopy and NMR spin-lock SLR, respectively, almost coincide. This excellent agreement points out that the two methods are sensitive to very similar motional correlations functions probing magnetic spin fluctuations and electrical relaxation processes, respectively.

References

[1] S. Ohta et al., J. Power Sources, 2012, 202, 332–335.
[2] B. Stanje et al., Ann. Phys. (Berlin), 2017, 529, 1700140.
[3] D. Rettenwander et al., Chem.
Mater., 2014, 26, 2617–2623.
[4] J. L. Allen et al., J. Power Sources, 2012, 206, 315–319.
[5] H. Buschmann et al., Phys.
Chem. Chem. Phys., 2011, 13, 19378–19392.
[6] P. Bottke et al., Chem. Mater., 2015, 27, pp 6571–6582
Fluorinated Phosphorus-Based Compounds As Multifunctional Additives/Co-Solvents for Advanced Lithium-Ion Battery Electrolytes
Authors: von Aspern Natascha , Diddens Diddo , Stubbmann-Kazakova Olesya , Kozel Volodymyr , Roeschenthaler Gerd-Volker , Winter Martin , Cekic-Laskovic Isidora 
Published: February 2020

In today’s society, the utilization of portable energy sources like lithium-ion batteries (LIBs) is of essential worth. However, LIBs still have certain limitations and bottlenecks addressed to nonaqueous aprotic electrolytes, as inevitable components for the operation of the battery.1 With this in line, state-of-the-art nonaqueous aprotic electrolytes (SOTA) reveal different challenges such as electrolyte decomposition and high flammability. One effective and cost favorable approach refers to the introduction of additives or co-solvents to the SOTA electrolyte.2-3 Hereby, the electrolyte decomposition can be minimized when increasing the cut-off potential (beyond 4.5 V vs. Li/Li+) that prevents the increased capacity fading of the battery. Furthermore, phosphorus (III and V) fluorinated or non-fluorinated compounds have been the subject of an investigation and can be featured as effective flame retardants.2-3 With the advance demand of energy in the last decades, an increase in the energy density, as well as an improvement in safety concerns are highly required for the advanced batteries, tailored for targeted application.2-5

In this work, several fluorinated cyclic phosphorus-based containing compounds were designed, synthesized and investigated as bifunctional - high-voltage and flame retardant – additives/co-solvent as electrolyte components for advanced LIB application. The selected molecules were correlated in respect to their structure-reactivity relationship and characterized by means of carefully selected physicochemical, electrochemical, analytical and structural methods. Furthermore, the influence of the fluorinated cyclic phosphorus-based additives/co-solvents on the overall performance of the graphite/NCM111 cells was studied. In addition, the flammability of electrolyte formulations were investigated. The results obtained from self-extinguishing time test (SET) and flash point determination, as well as TGA and DSC measurements were correlated to theoretical calculations to understand the mechanism of the combustion.
This systematical approach allows to understand the structure-reactivity relationship of the selected compounds, their impact on the overall battery chemistry, performance and safety and helps, to further tailor the properties of electrolyte additives/co-solvents for specific application.
1 D. Gao, RSC Adv. (2015), 5, 17566.
2 K. Xu, Chem. Rev. (2004), 104, 4303.
3 K. Xu, Chem. Rev. (2014), 114, 11503.
4 S. S. Zhang, J. Power Sources (2006), 162, 1379.
5 M. Asif, Renew. Sustainable Energy Rev. (2007), 11, 1388.
The Effect of Pore Connectivity on Li Dendrite Propagation within Llzo Electrolytes Observed with Synchrotron X-Ray Tomography
Authors: Hatzell Kelsey B , Dixit Marm , Shen Fengyu , Xiao Xianghui 
Published: February 2020

Li7La3Zr2O12 (LLZO) is a garnet type material that demonstrates promising characteristics for all solid-state battery applications due to its high Li-ion conductivity and its compatibility with Li metal1,2. The primary limitation of LLZO is the propensity for short-circuiting at low current densities3. Microstructure features such as grain boundaries, pore character, and density all contribute to this shorting phenomenon. Toward the goal of understanding structure-processing relationships for practical design of solid electrolytes, the present study tracks structural transformations in solid electrolytes processed at three different temperatures (1000, 1050 and 1150 °C) using synchrotron x-ray tomography4. A sub volume of 300 μm3 captures the heterogeneity of the solid electrolyte microstructure while minimizing the computational intensity associated with 3D reconstructions. While the porosity decreases with increasing temperature, the underlying connectivity of the pore region increases. Solid electrolytes with interconnected pores short circuit at lower critical current densities than samples with less connected pores.
[1]Thompson, Travis, et al. "Tetragonal vs. cubic phase stability in Al–free Ta doped Li 7 La 3 Zr 2 O 12 (LLZO)." Journal of Materials Chemistry A 2.33 (2014): 13431-13436.
[2] Sharafi, Asma, et al. "Characterizing the Li–Li 7 La 3 Zr 2 O 12 interface stability and kinetics as a function of temperature and current density." Journal of Power Sources 302 (2016): 135-139.
[3] Cheng, Eric Jianfeng, Asma Sharafi, and Jeff Sakamoto. "Intergranular Li metal propagation through polycrystalline Li 6.25 Al 0.25 La 3 Zr 2 O 12 ceramic electrolyte." Electrochimica Acta 223 (2017): 85-91.
[4] Hatzell, Kelsey B., et al. "Direct observation of active material interactions in flowable electrodes using X-ray tomography." Faraday discussions 199 (2017): 511-524.

Figure 1
A Macroscopic Model to Describe the Composite Effects of a LiFePO4 PVDF/Csp Cell Based on Effective Transport Parameters
Authors: Mendoza Santos Ilda Olivia , Vazquez-Arenas J. , González Ignacio , Castillo Araiza Carlos Omar 
Published: February 2020

Li-ion batteries have been positioned like one of the best storage devices today there is a satisfactory combination of electrodes and electrolytes to be used for rechargeable Li-ion batteries in the electronic market due to their high energy densities (e.g. portable media, computers and small equipment), however, it is overriding to account for numerous problems related with transport mechanisms of charge and mass that significantly affect their capacities and power. The understanding of these mechanisms is complex due to various kinetic and transport phenomena interacting within the battery, and the difficulty of estimating local variables such as concentrations, potential, among other.
Mathematical modeling based on porous electrode theory [1] has been a powerful tool to understand and optimize the functioning performance of these devices. Nevertheless, the role of each component in the porous matrix of the electrode has not been accounted for since under this perception the battery is described as a whole identity [2, 3]. In this direction, the effect of electrode composition (i.e. variation of active and inactive material) on rate capabilities cannot be explained by these models.
In the present work, a macroscopic model is proposed relying on the assumption that the electrode is a porous solid matrix where active and inactive components should be separately expressed but interacting in solid and liquid phases. This enables to account for the experimental discharge of a semi cell Li °/1M LiPF6 in 1:1:1 EC:DMC:EMC/LiFePO4:PVDF-Csp considering effective transport parameters and the kinetic proposal taking in count the active material fractionin the cathode composition.
Acknowledgements:
I. Santos is grateful to CONACYT for the scholarship granted to pursue his doctoral studies.
References:
[1] Newman, J. and W. Tiedemann, AIChE Journal, 21 (1975) 25-41
[2] West, K., T. Jacobsen, and S. Atlung, Journal of The Electrochemical Society, 129 (1982) 1480-1485
[3] Farkhondeh, M., et al., Physical Chemistry Chemical Physics, 16 (2014) 22555-22565.
Large-Scale First-Principles Simulation on Li-Intercalated Graphite
Authors: Nakata Ayako , Miyazaki Tsuyoshi , Sodeyama Keitaro 
Published: February 2020

Lithium-ion batteries (LIBs) have attracted considerable attention for use in larger power sources like electric vehicles and energy storage system because of their high energy densities. In the LIB, carbon materials, such as highly oriented pyrolytic graphite (HOPG), are used as negative electrode. During the charge and discharge cycle, Li-ions are intercalated to the graphite. For the Li- ions intercalation into the layered graphite, phase transition between different staging structures occurs. At first, Li-ions are intercalated randomly to whole layers, called dilute stage1. Next, stage transformation between dilute stage 1 and stage 4, stage 4 and stage 2, stage 2 and stage 1 proceed. This stage transformation plays an important role for the LIB performance, especially the maximum capacity and charge discharge rate of batteries. Regarding atomic scale mechanism of the stage transformation, Daumas and Hérold model was proposed. In the model, fully occupied and empty region of Li-ions in the layers exist, but the layers can be distorted to localize the Li-ion occupied region. This layer distortion is the key for the stage transformation. To clarify this mechanism from the view point of the first-principles study, large-scale calculations is required.
In this study, we investigate the atomic and electronic structures of Li-intercalated graphite by using our large-scale DFT program CONQUEST [1]. The CONQUEST code uses real-space local orbital functions to express density matrices instead of the plane-wave basis. Especially, recently-developed “multi-site method” [2] reduces the number of local orbital basis functions to be minimal size keeping high accuracy, which reduces the computational cost dramatically and enables us to treat large systems containing 10,000+ atoms. The comparison of the geometries and electronic structures of Li-intercalated graphite at several stage structures with several thousand atoms (as in figure 1) will be discussed in the presentation.
[1] http://www.order-n.org/
[2] A. Nakata, D. R. Bowler, T. Miyazaki, Phys. Chem. Chem. Phys. 17, 31427 (2015).
Figure 1. Large-scale simulation model of Li-intercalated graphite (stage1).

Figure 1
3-D Printing with Carbon Nanotube Composites
Authors: Farthing Tyler , Mukherjee Santanu , Singh Gurpreet 
Published: February 2020

The mechanical benefits gained from using carbon nanotubes in liquid thermosetting resins gives stereolithograhy 3-D printing a promising future in the world of additive manufacturing. There are some challenges faced with obtaining consistent results in this area of research, however. The primary reason is due to the unique aspect ratio of the carbon nanotubes which leads to uneven distribution during the preparation of the polymer matrix composite. Furthermore, it is also difficult to achieve complete photo-polymerization of the part due to the carbon nanotubes interference with the UV light during the curing process.
Here the effect of MWCNT filler on mechanical strength and stiffness of 3-D printed polymer-matrix composite using stereolithography printer is studied. MWCNTs were de-agglomerated in Toluene and introduced into photopolymer resin at various weight loadings. 3-D printing was performed with the composite resin followed by uniaxial tensile testing to obtain data to analyze for possible mechanical stress and strength benefits. This work concluded that the addition of .005 weight % of MWCNT showed an improvement of 24.8 % and 9.6 % for stress failure and Young’s Modulus respectively compared to neat sample. The addition of 0.01 and 0.02 weight % had adverse effects of lowering the Young’s Modulus and causing stress failure.
Self-Healing Supramolecular Hydrogel: Polyrotaxane Cross-Linked By Host-Guest Interactions
Authors: Kobayashi Yuichiro , Takashima Yoshinori , Yamaguchi Hiroyasu , Harada Akira 
Published: February 2020

Self-healing materials, which can extend the service life of objects, have attracted much attention in efforts to create a sustainable society. One of the most important approaches to obtain self-healing materials is non-covalently bonded systems. Unlike covalently bonds, non-covalent interactions such as hydrogen bonds, π-π stacking interactions, metal-ligand coordination bonds, and host-guest interactions [1] are reversible. It has been recently reported that materials recover their original mechanical property when they are damaged. This self-healing property occurs by introducing a non-covalent interaction site into the end or side chain of a polymer. In this regard, the healing time is affected by the mobility of the polymer chain because self-healing occurs by the formation of non-covalent bonds between the responsible sites via non-covalent interactions in the polymer. To address the expected practical demands and requirements, the development of a self-healing material that recovers in a short time is in high demand.
For this purpose, we employ polyrotaxanes (PRxs), which are a class of supramolecular threaded macromolecules in which cyclic molecules are threaded onto linear polymers.[2] The advantage of PRxs is that threaded cyclic compounds are freely mobile along the linear polymer because they are non-covalently assembled between the linear polymer and many cyclic molecules. Thus, compared to functional groups conjugated to a conventional polymer side chain, the functional group conjugated with the cyclic molecules in PRx can effectively bind to the target.
Herein we report a self-healing material based on PRx through host-guest interactions. This material was prepared by radical copolymerization of acryl amide (AAm) and the host monomer in the presence of PRx introduced with guest molecules. The resulting material exhibits a self-healing property, and its healing speed is faster than a self-healing material without PRx.
[1] (a) T. Kakuta, Y. Takashima, M. Nakahata, M. Otsubo, H. Yamaguchi, A. Harada, Adv. Mater. 2013, 25, 2849-2853. (b) M. Nakahata, Y. Takashima, A. Harada, Macromol. Rapid. Commun. 2016, 37, 86-92.
[2] (a) Y. Kobayashi, Y. Nakamitsu, Y. Zheng, Y. Takashima, H. Yamaguchi, A. Harada, Chem. Commun. accepted (b) A. Harada, J. Li, M. Kamachi, Nature
1992, 356, 325-327.

Figure 1. (a) Chemical structures of Ad(x)DMEDAPRx–βCD gel, Ad(x)–βCD gel, and AAm(x) gel. (b) Schematic illustration of the self-healing feature of Ad(x)DMEDAPRx–βCD gel. Here, x represents the mol% of the cross-linking unit.

Figure 1