bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study about Electrostatic Deposition of CdTe Quantum Dots on Glassy Carbon Electrodes
Authors: Muñoz Eduardo Carlo , Navarrete Emilio Alonso , Rojas Víctor , Romero Mario , Henríquez Rodrigo Gonzalo , Schrebler Ricardo Silvio , Córdova Ricardo Alejandro 
Published: February 2020

Quantum Dots (QDs) are semiconductor nanocrystals. These materials are characterized for its continuous absorption spectra at wavelengths ranging from ultraviolet to visible. This feature is directly related to the size of the nanoparticle. Considering their applications, these materials can be employed in solar cells, lasers, light emitting diodes, electronic devices, among others [[i],[ii]]. However, one of the most attractive applications for QDs has been as sensors or biosensor.
In this work, the synthesis of CdTe Quantum Dots was carried out in aqueous media using Na2TeO3 and CdCl2 as precursors of Te2- and Cd2+ ions, respectively, mercaptosuccinic acid (MSA) as capping agent and NaBH4 as reducing agent. The QDs obtained as colloids were purified and characterized by transmission electron microscopy (TEM), while their optical properties were characterized by UV-visible spectroscopy. After, an electrostatic deposition of the QDs on a Glassy Carbon (GC) electrode was done. This last was carried out applying a positive potential value regarding to the zero charge potential of the electrode in an aqueous media, and the influence of the potential value, deposition time was determined by means cyclic voltammetry. A study of surface conductivity changes of the glassy carbon electrodes after QDs deposition was performed by means Scanning Electrochemical Microscopy (SECM). With this was possible to observe aggregates of CdTe QDs deposited on GC electrodes indicating a possible irreversible electrostatic deposition.

[
[i]
] R. Debnath, J. Tang, D. Barkhouse, X. Wang, A. Pattantyus-Abraham, L. Brzozowski, L. Levina, and E. Sargent, J. Am. Chem. Soc. 132 (2010) 5952-5953.

[
[ii]
] P. Kamat, K. Tvrdy, D. Baker, and J. Radich, Chem. Rev. 110 (2010) 6664-6688.

Figure 1
Supported Heterogeneous Gold Nanoparticles As a Catalyst for the 4-Nitrophenol Hydrogenation Reaction
Authors: Abdel-Fattah Tarek M , Jusino Angelica 
Published: February 2020

Bulk gold cannot oxidize in air and is known for its minimal reactive ability with many chemical reagents. Because of this, bulk gold is known to be chemically inert, and this low activity is due to the particle sizes.1 However, gold nanoparticles (AuNPs) are the most highly active of catalyst due to the lack of a stable oxide (unlike most elements).2–4 As the Fermi potential of metal nanoparticles becomes more negative, they exhibit a substantial decrease in potential. The result of this unique property allows them to behave as catalysts in electron transfer processes, such as hydrogenation reactions. Electrical, optical, and catalytic properties are frequently seen in small nanomaterials and gold nanoparticle catalysts show excellent potential for the selective oxidation or hydrogenation of organic substrates.1,5 It is believed that gold nanoparticles will be key building blocks for many disciplines in the 21st century. For example, their individual particle size behaviors, and the electronic, magnetic and optical properties (quantum size effect), show great promises to the catalysis, nanotechnology, and biological field.2–4

Four different sizes of nanoparticles were synthesized and then suspended on four different economically favorable supports. The catalytic properties were investigated in this study with the reduction of 4-nitrophenol, a common hydrogenation reaction. Kinetics of the catalysis was monitored with UV-Vis spectrophotometry and samples were characterized with both transmission electron microscopy (TEM) and X-ray fluorescence (XRF). It was found that all reactions followed first order kinetics. Activated carbon did not behave as a catalytic surface, but was found to absorb the nitrophenol for all nanoparticle sizes. Glass wool and the largest AuNP (53.5nm) proved to be the best support by providing the fastest rate constants. This heterogeneous catalyst was also found to be recyclable.

REFERENCES

1) Abdel-Fattah, T. M. & Wixtrom, A. Catalytic reduction of 4-nitrophenol using gold nanoparticles supported on carbon nanotubes. ECS J. Solid State Sci. Technol. 3, M18–M20 (2014).
2) Seoudi, R. & Said, D. A. Studies on the Effect of the Capping Materials on the Spherical Gold Nanoparticles Catalytic Activity. World J. Nano Sci. Eng. 01, 51–61 (2011).
3) Daniel, M.-C. & Astruc, D. Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology. Chem. Rev. 104, 293–346 (2004).
4) Heddle, J. Gold Nanoparticle-Biological Molecule Interactions and Catalysis. Catalysts 3, 683–708 (2013).
5) Huang, J. et al. Ag Dendrite-Based Au/Ag Bimetallic Nanostructures with Strongly Enhanced Catalytic Activity. Langmuir 25, 11890–11896 (2009).
Growth Mechanism of Silver Nanowires By Polyol Process and Their Application for Transparent Conductive Thin Film
Authors: Hsu Hsun-Feng , Hong Liang-Zheng , Lin Cheng-Fu , Lyu Cheng-Han 
Published: February 2020

One-dimensional nanowires have attracted intense interest due to their unique photo-electric, magnetic and thermal conductive characteristics. Silver nanowire (Ag NW) based thin films have been recently used as transparent conductive films because of their high optical transparency, low sheet resistance and flexibility. Previous studies have demonstrated that polyol process, one of widely used method for Ag NWs chemical synthesis, could be used to produce Ag NWs by adding Cl- ions with appropriate concentration in the process. Besides Ag NWs, Ag particles could also be formed with addition of much higher or lower Cl- ions. However, optimal reaction time and concentration of Cl-ions for Ag NWs synthesis have rarely been reported.
In this study, Ethylene Glycol (EG) solution with AgNO3was prepared and added in EG solution with Polyvinylpyrrolidone (PVP) for Ag NW formation. Mechanism of Ag NW formation was investigated by adding different amount of NaCl for different reaction time.
The results show that Ag nanoparticles were initially formed and gradually turned into nanowires because of PVP addition.
However, Ag NWs would gradually shorten while growing at critical length in the reaction. This interesting phenomenon could be explained by the reducing of surface energy. Furthermore, the longest Ag NWs could be obtained under condition of optimal reaction time and concentration of Cl-ions. These Ag NWs were prepared as transparent conductive thin films for optical transmittance and electrical conductivity measurements. Transparent conductive thin films with long AgNWs have better conductivity than short ones, and their stability would be further increased while coating the Polymethylmethacrylate (PMMA) as protective layer.
Impedance Spectra Associated with Metal Deposition at the Negative Electrode from Contaminated Metal Particles at the Positive Electrode in a Lithium Ion Battery
Authors: Nakajima Hironori , Inada Akiko , Kitahara Tatsumi , Nagata Yusaku 
Published: February 2020

Lithium ion batteries have the issue of internal short circuiting by the electrodeposition of metal at the negative electrode. This deposition follows the dissolution of contaminated metal particles incorporated into the positive electrode in manufacturing process. Thus, we have investigated the dissolution­/deposition behavior of metals such as copper, nickel, iron, and stainless steel so far1. We also proposed a diagnosis method for the incorporation of the metal particles by electrochemical impedance spectroscopy, taking advantage of characteristic changes of the impedance spectra (phase angle) between 10-­1 Hz1. In the present study, we investigate the time variation of the impedance spectra associated with the growth of the metal deposits at the negative electrode.
Test cells were assembled with positive electrodes of metal plates of iron, nickel and stainless steel, electrolyte solution of ethylene carbonate (EC)/diethylcarbonate (DEC) (1:1 vol.) containing 1 M LiPF6, and negative electrodes of graphite mixed with PVDF binder.
Potential between the metal plates and the negative electrode was maintained at 4.2 V by a potentio/galvanostat to electrochemically dissolve the metal plate at the positive electrode and deposit the metals at the negative electrode, while the negative electrode was maintained at 0.3 V against a lithium wire in the test cell by an auxiliary potentio/galvanostat to reproduce the potentials in a lithium ion battery.
We observe the metal deposits at the negative electrodes from the iron, nickel and stainless steel plates by FE-SEM and EDX. Time variations of the phase angle in the impedance spectra between 10­-1 Hz for the above metal deposits are correlated with the metal growth, taking into account the impedance of the SEI layer at the metal surface.
1. Hironori Nakajima, and Tatsumi Kitahara, Diagnosis Method to Detect the Incorporation of Metallic Particles in a Lithium Ion Battery, ECS Trans., Vol. 68, 2, 59-74 (2015).
Pseudocapacitance and Excellent Cyclability of Quinones on 2D Graphene
Authors: Boota Muhammad , Chen Chi , Bécuwe Matthieu , Miao Ling , Gogotsi Yury 
Published: February 2020

Electrochemically active organic materials are attractive solution for the energy storage devices due to their natural abundance, relatively low cost, structural diversity and sustainability.1,2 Conducting polymers are well studied organic systems for the supercapacitors and batteries.3,4 Although, they exhibit high initial capacitance, their structural degradation due to ion doping/undoping leads to capacitance fade upon moderate cycling. Thus, it is needed to explore new organic materials which offer high redox capacitance, and longer cycling lifespan for the energy storage devices.
Herein, we report 3D interconnected xerogel composed of redox-active 2,5-dimethoxy-1,4-benzoquinone (DMQ) decorated on reduced graphene oxide sheets (DMQ@rGO), via one-step hydrothermal method. The DMQ not only provided fast two-electron redox but also yielded an open-structured hierarchical architecture by acting as a spacer between the rGO sheets. When binder-free optimized composition of DMQ@rGO was tested as a pseudocapacitive electrode, it showed high capacitance (650 F/g, 780 F/cm3 at 5 mV/s) and excellent capacitance retention of 99% after 25000 cycles at 50 mV/s in 1M H2SO4. Furthermore, density functional theory calculations are used to elucidate the charge storage mechanism, binding energies, adsorption orientation of DMQ, charge redistribution and density of the states. Our combined experimental and theoretical results determine that careful selection of the quinone structure, conductive substrate and electrode architecture altogether play a crucial role for high capacitance and long cycling performance.
1 B. Huskinson, M. P. Marshak, C. Suh, S. Er, M. R. Gerhardt, C. J. Galvin, X. Chen, A. Aspuru-Guzik, R. G. Gordon and M. J. Aziz, Nature, 2014, 505, 195–8.
2 M. Boota, B. Anasori, C. Voigt, M.-Q. Zhao, M. W. Barsoum and Y. Gogotsi, Adv. Mater., 2015, 28, 1517–22.
3 D. Vonlanthen, P. Lazarev, K. a. See, F. Wudl and A. J. Heeger, Adv. Mater., 2014, 26, 5095–5100.
4 M. Boota, M. P. Paranthaman, A. K. Naskar, Y. Li, K. Akato and Y. Gogotsi, ChemSusChem, 2015, 8, 3576–3581.
Thick Electrode Designs for Lithium Ion Batteries
Authors: Chiang Yet-Ming 
Published: February 2020

A typical lithium-ion cell contains about 25 individual materials layers per 1 mm of stack thickness, an evolutionary result after a quarter century of technology development that remains non-optimal from materials cost and volume utilization viewpoints. This talk will discuss recent work at MIT and 24M Technologies on thick electrode designs that can reduce materials cost from non-energy-storing components while delivering necessary electrochemical kinetics and remaining highly manufacturable. 24M has developed a new semisolid electrode technology and manufacturing method that yields electrodes with several times the thickness and area capacity of conventional lithium ion electrodes, yet has transport kinetics rapid enough for all but very high power applications. The semisolid lithium ion cells have significantly fewer inactive component layers than conventional lithium-ion cells of similar performance, and can be produced by a radically simpler process that obviates most of the electrode fabrication unit operations in conventional Li-ion, thereby lowering both materials and manufacturing cost. At MIT, magnetic alignment methods that produce low tortuosity porosity from sacrificial pore formers have been developed, that are rapid, scalable, and naturally produce aligned porosity favorably oriented normal to the electrode plane.
Support for this work by the U.S. Department of Energy through the ARPA-E program, the Vehicle Technologies Office of EERE, and the Advanced Battery Materials Research (BMR) program is gratefully acknowledged.
Fail-Safe System for High Energy Density Power Li-Ion Batteries
Authors: Mao Huanyu 
Published: February 2020

As longer driving range becomes an important feature for pure electric vehicles, higher energy density power batteries are needed. However, the battery safety for higher energy density power batteries has been an obstacle. An idea of “Fail-Safe” and its measures can largely reduce the risk of using high energy density power Li – Ion batteries. This talk will describe how our Fail-Safe system working to prevent the overall packs disasters when few cell had thermo runaway inside the battery pack.
Morphological Evolution of Multilayer Ni/NiO Thin Film Anodes during Lithiation
Authors: Evmenenko Guennadi , Fister Timothy T , Buchholz Donald Bruce , Esbenshade Jennifer , Chen Xiao , Li Qianqian , Wu Jinsong , Dravid Vinayak , Fenter Paul , Bedzyk Michael J. 
Published: February 2020

We focus on in-operando structural evolution of model Li-ion battery anodes, which are comprised of multi-bilayer Ni/NiO films with active NiO layers sandwiched between buffer Ni layers. The films were deposited on sapphire via pulsed laser deposition (PLD). The morphological changes accompanying lithiation were tracked via in-situ and ex-situ X-ray reflectivity (XRR) and cross-sectional transmission electron microscopy in a series of films produced by systematically varying the thicknesses of active and buffer layers (20 Å to 200 Å) and the number of periodic bilayers (1 to 5). The key results of these combined studies are:

Complete lithiation of all the active NiO layers occurs only when the thickness of the buffer Ni layers is less than ~50 Å. For fully lithiated films, the active NiO layers doubled in thickness while being converted to Li2O layers and the reduced Ni from the NiO migrated to the bordering Ni buffer layers. This uniaxial lithiation process of multi-bilayer anodes started at the top and progressed toward the bottom of the stack. The expansion was accompanied initially by lateral inhomogeneities, which diminished over time leading to laterally uniform lithiated Li2O/Ni multilayers.

Ni layers with a thickness >50 Å present a kinetic barrier for the diffusion of lithium ions. This results in a partial lithiation of Ni/NiO multilayer anodes such that only the top NiO layer is lithiated.

XRR shows that for the 5-bilayer Ni/NiO films, the electron density of the fully lithiated layers is a constant (no density fluctuations). This attests that the reduced Ni is rather uniformly distributed inside the Li2O matrix after the completion of the conversion reaction. This contrasts the situation for 2-bilayer Ni/NiO films. Here, low-density regions are observed inside the fully lithiated active layers near the Ni interlayers.

For the fully lithiated Ni/NiO 5-bilayer films, the thickness of the Ni layers increases by 6-7 Å (roughly two atomic diameters of Ni), suggesting segregation of reduced Ni at the Ni/lithiated NiO layers. Consistent with this, the thickness of the Ni layer increases by 3-4 Å when only the top NiO layer is lithiated (for Ni thickness >50 Å, see 2 above).

In my presentation, I will discuss the mechanisms of the observed structural transformations. These are the first systematic studies of vertically digitized multilayer anodes that precisely determine the relationships between the morphological changes and the film architecture during lithiation.
This research was supported by the Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
AlOOH-Based Nanocomposite Separators for Enhanced Safety and Performance
Authors: Avison David William , Carlson Steve , Sloan Ben 
Published: February 2020

The separator, while typically regarded as an inactive component of the battery, is widely recognized as being critical to cell efficacy and safety; the importance of their role in cell design and overall battery performance has become increasingly important with the move to higher energy density storage systems to meet industry needs.
The present paper outlines the many key functions that separators serve in lithium-ion batteries and describes a separator design – specifically, AlOOH-based nanocomposite membranes – which addresses several critical safety concerns for high performance lithium-ion batteries, while maintaining cell longevity. These nanoporous membranes exhibit an extremely narrow pore size distribution, outstanding dimensional stability, excellent compression resistance, and very high thermal conductivity. Safety and cell performance characteristics are correlated with fundamental materials and separator design parameters using a range of analytical techniques, characterization methods, and cell abuse tests. Opportunities for enhanced functionality are discussed.
Corrosion Prevention Mechanism of Aluminum Metal in Superconcentrated Electrolytes
Authors: Chiang Ching Hua , Yamada Yuki , Sodeyama Keitaro , Wang Jianhui , Tateyama Yoshitaka , Yamada Atsuo 
Published: February 2020

Metal corrosion is a serious problem that has beset various electrochemical systems. For lithium-ion batteries, oxidative corrosion of an Al current collector has been a great challenge in designing new electrolyte materials, and only a few lithium salts (e.g., LiPF6) are in practical use. Lithium bis(fluorosulfonyl)amide (LiFSA, LiN(SO2F)2) has attracted increasing attention as a state-of-the-art Li salt due to its high thermal/chemical stability and highly dissociative nature, but LiFSA-based electrolytes are known to induce severe oxidative corrosion of the Al current collector, which limits its widespread applications in lithium-ion batteries. The present work shows effective suppression of Al corrosion up to 4.5 V vs Li+/Li by using highly concentrated LiFSA electrolytes.1-4 The corrosion prevention mechanism can be interpreted in relation to a remarkable change in solution structures; all solvent molecules coordinate to Li+ and free solvent molecules disappear over a certain threshold concentration, as is evident from both spectroscopic analyses and first-principle molecular dynamics simulations. The stabilization of the Al current collector through the control of electrolyte solution structures is advantageous over LiPF6-based electrolytes, because the present case does not depend on F-, which also has negative effects on battery performance. Using highly concentrated LiFSA/acetonitrile (AN) electrolytes without free solvent molecules (5.0 and 6.0 mol dm-
3), we demonstrated highly reversible charge-discharge cycling of both LiMn2O4/Li cell (with an Al current collector)3 and graphite/Li cell,2 which cannot be achieved in less concentrated electrolytes (3.0 and 4.0 mol dm-
3). Furthermore, the rate performance far exceeds that in a state-of-the-art commercial electrolyte. This finding of superior performance in superconcentrated electrolyte will be an important breakthrough in developing a new electrolyte design strategy for advanced high-rate lithium-ion batteries.
1. Yuki Yamada et al., Chem. Commun., 49, 11194 (2013).
2. Yuki Yamada et al., J. Am. Chem. Soc., 136, 5039 (2014).
3. Yuki Yamada et al., ChemElectroChem, 2, 1687 (2015).
4. Yuki Yamada et al., J. Electrochem. Soc., 162, A2406 (2015).

Figure 1
Superconcentrated Electrolytes for Sodium-Ion Batteries
Authors: Takada Koji , Yamada Yuki , Wang Jianhui , Lien Chien-Hung , Hirata Kazuhisa , Kawase Takeo , Yamada Atsuo 
Published: February 2020

Sodium-ion batteries are receiving intense attention as an inexpensive yet high-performance rechargeable battery to possibly replace current lithium-ion chemistries in future. A myriad of positive and negative electrode materials have so far been reported for sodium-ion batteries and, interestingly, some of them exhibit superior performance (e.g., voltage, capacity, kinetics, or cycleability) than state-of-the-art electrodes for lithium-ion batteries. On the other hand, there are only a few studies on liquid electrolyte design for sodium-ion batteries. In particular, high reductive/oxidative stability is strongly required for electrolyte materials to achieve prolonged charge-discharge cycling of hard carbon anodes and high-voltage cathodes. Recently, superconcentrated electrolytes are being recognized as a new class of highly stable electrolytes for lithium-based batteries.1-3 In the present work, we report basic physicochemical and electrochemical properties of sodium salt-based superconcentrated electrolytes. First, we study the effects of cations, anions, and solvents on the ionic conductivity and viscosity of electrolytes at various concentrations. Based on the results, important factors to dominate the physicochemical properties are discussed. Next, we study charge-discharge behavior of hard carbon and sodium metal electrodes in sodium salt-based superconcentrated electrolytes. We have found much better cycleability of the electrodes in superconcentrated electrolytes than in conventional dilute electrolytes, suggesting that the sodium salt-based superconcentrated electrolytes have enhanced reductive stability.
1. K. Yoshida et al., J. Am. Chem. Soc., 133, 13121 (2011).
2. Y. Yamada et al., J. Am. Chem. Soc., 136, 5039 (2014).
3. Y. Yamada et al., J. Electrochem. Soc., 162, A2406 (2015).