bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel Liquid and Polymer Electrolytes for Lithium-Sulfur Batteries
Authors: Panero Stefania , Navarra Maria Assunta , Lombardo Lucia , Savi Fabiana , Aguilera Luis , Elamin Khalid , Matic Aleksandar 
Published: February 2020

A major hurdle still hindering the practical development of the highly desirable lithium-sulfur batteries is the solubility in organic, carbonate-based electrolytes of polysulfide compounds formed as intermediates during charge and discharge processes. This high solubility results in a loss of active mass, which is reflected in a low utilization of the sulfur cathode and in severe capacity decay upon cycling. The dissolved polysulfide anions, by migration through the electrolyte, may react with the lithium metal anode to form insoluble products on its surface; this process also negatively impacts the battery operation. Various strategies to address the solubility issue have been explored, including the design of modified organic liquid electrolytes, the use of ionic liquid solutions and of polymer electrolytes [1, 2].
In this work we present a combined strategy, where optimized liquid electrolytes, composed by ether-based solvents and an ionic liquid additive, were used to swell a selected polymer matrix. This allows the formation of composite, highly conductive, gelled polymer electrolytes able to control the dissolution of the sulfide anions. In our approach, a dry poly(ethylene oxide) (PEO) membrane was first prepared, through a solvent-free route [3, 4], and then activated by the liquid electrolyte, according to a well addressed swelling procedure.
Thermal, spectroscopical and electrochemical characterizations were performed on both liquid and gelled polymer electrolytes and will be discussed. The successful practical application in Li-S cells was demonstrated by prolonged galvanostatic cycles where very high and stable capacity values (i.e., 900 mAh/g) were achieved.
Acknowledgments:
The results of this work have been obtained by the financial support of the European Community within the Seventh Framework Program LISSEN (Lithium Sulfur Superbattery Exploiting Nanotechnology) Project (project number 314282).
[1] Junghoon Kim , Dong-Ju Lee , Hun-Gi Jung , Yang-Kook Sun , Jusef Hassoun , Bruno Scrosati, Adv. Funct. Mater. 2013, 23, 1076–1080
[2] Rezan Demir-Cakan, Mathieu Morcrette, Gangulibabu, Aur´elie Gu´eguen, R´emi Dedryv`ere, Jean-Marie Tarascon, Energy Environ. Sci., 2013, 6, 176–182
[3] P.P Prosini, S Passerini, R Vellone, W.H Smyrl - J. Power Sources, 75 (1998), p. 73
[4] G.B Appetecchi, S Scaccia, S Passerini - J. Electrochem. Soc., 147 (2000), p. 4448
(Invited) Nature of MIEC Cathode/Electrolyte Interfaces
Authors: Ivers-Tiffée Ellen , Szász Julian , Wankmüller Florian , Wilde Virginia , Störmer Heike , Gerthsen Dagmar , Weber André 
Published: February 2020

Modern solid oxide fuel cells (SOFC) use a high-performance mixed ionic-electronic conducting (MIEC) La1-xSrxCo1-yFeyO3-δ (LSCF) cathode. This perovskite, when directly applied to Y2O3 stabilized ZrO2 (YSZ), forms a blocking layer of Strontiumzirconate (SrZrO3 - SZO). This secondary phase reaction is prevented by inserting a dense Gd-doped Ceria (GDC) between LSCF and YSZ [1]. Mostly, the GDC interlayer is screen printed and the correct density is assured by subsequent sintering. This high temperature treatment however causes a low-ionic conductivity GDC-YSZ interdiffusion phase [2]. The correct balance between GDC density and GDC-YSZ interdiffusion is crucial for achieving highly functional GDC interlayers. Microstructure evolution after GDC sintering (Fig.1a) and after LSCF sintering (Fig.1b) reveals the dramatic influence of LSCF as sintering aid for porous, fine grained GDC layers. On the other hand, GDC sintered at 1400°C shows effective inhibition of SZO formation, but enhanced GDC-YSZ interdiffusion. The changing nature of the gas/cathode/electrolyte interface goes hand in hand with a drastic decrease in ASRcat by over two orders of magnitude. The interface changes from a layer sequence LSCF/GDC/SZO/GDC-YSZ/YSZ at 1100°C gradually to LSCF/GDC/GDC-YSZ/YSZ at 1400°C. We will discuss the origin of this solid/gas interface in detail, and link the effects to electrochemical performance, i.e., contributions of the electrolyte phases (GDC, GDC-YSZ interdiffusion, YSZ) to the ohmic resistance, and contributions of LSCF, SZO and GDC to the cathodic polarization resistance (ASRcat).
These findings confirm a complex heterogeneous solid/gas interface at a mixed conducting cathode/electrolyte side of a SOFC cell. Its drastic influence on electrochemical performance points to the necessity of understanding the nature of MIEC cathode/electrolyte interfaces for individual cell concepts.
References
[1] H. Yokokawa, N. Sakai, T. Horita, K. Yamaji, M.E. Brito, H. Kishimoto, J. Alloys Compd. 452 (2008) 41.
[2] A. Tsoga, A. Naoumidis, A. Gupta, D. Stöver, Mater. Sci. Forum 308-311 (1999) 794.

Figure 1
An Effective Way of Suppressing Main Degradation Mechanisms of Carbon Supported High Surface Area Catalysts at Elevated Temperatures
Authors: Polymeros George , Baldizzone Claudio , Geiger Simon , Grote Jan-Philip , Knossalla Johannes , Mezzavilla Stefano , Cherevko Serhiy , Zeradjanin Aleksandar R. , Schüth Ferdi , Mayrhofer Karl J.J. 
Published: February 2020

On the pathway to the broader implementation of low temperature polymer electrolyte fuel cells (PEMCs) their performance, which is defined by the equally important factors of the activity and stability of the electrocatalyst, has to be further improved for meeting the demanding benchmarks. Various studies have been lately conducted directly on PEMFCs as well as ex-situ in order to firstly understand and then improve the stability issues, especially concerning the catalyst on the cathode. This work intends to further enlighten and rationally disentangle the complex interplay between the different aging mechanisms of this electrode and at the same time proposes a new strategy for circumventing considerable active surface area losses by tuning the morphology of the electrocatalytic layer. For this reason two Pt to carbon supported nanocatalysts are put to the test which are different only in respect to the geometry and nature of the carbon support. Thanks to the combination of several advanced experimental techniques the dominating degradation mechanism of each stage of a demanding/long degradation protocol will be demonstrated. The techniques applied are namely the rotating disk electrode (RDE) setup for the standard electrochemical characterization, the identical-location transmission electron microscopy (IL-TEM) to demonstrate the consecutive stages of the degradation of identical locations of the electrocatalyst on the nanometer scale, the coupled scanning flow cell (SFC) to an inductively coupled plasma mass spectrometer (ICP-MS) to investigate the dissolution of the Pt catalyst during the degradation process in-situ and the SFC coupled to an online electrochemical mass spectrometer (OLEMS) to study the corrosion process of the carbon support in-situ. For the sake of the application relevant conclusions of this study all the aforementioned techniques were operated in application oriented temperature (60 oC). Although dealing with a specific nano-engineered class of materials, the reported results are of high interest for the whole catalysis/energy conversion community, as they offer an alternative pathway for increasing the performance of the electrode by refining the catalytic support.
Hydrogen Peroxide Reduction in Aqueous Electrolytes: Influence of a Heterogeneous Decomposition Step
Authors: Georgescu Nicholas Stefan , Scherson Daniel 
Published: February 2020

It has been traditionally assumed that the reduction of hydrogen peroxide proceeds by a simple, first-order, 2-electron reduction, to yield water as the product. Under this model, a plot of the reciprocal of the current vs the reciprocal square root of the rotation rate, known as a Koutecky-Levich plot, should be linear, from which kinetic information can be obtained based on the magnitude of the intercepts as a function of the overpotential. However, close inspection of many such plots reported in the literature do exhibit some curvature especially at high rotation rates and low overpotential, a behavior that has been largely ignored but which may affect the interpretation of such plots1. One reaction seldom considered in this context is the well-documented heterogeneous disproportionation of hydrogen peroxide, a process known to occur on many surfaces that yields dioxygen2, a species that could subsequently reduce and thus contribute to the overall current observed (see Scheme 1). According to this Scheme, the current derived from the mass balances associated with peroxide and dioxygen is expressed in Equation 1.
Shown in Panel A, Figure 1, are a series of Koutecky-Levich plots based upon this formalism for three reasonable values of the heterogeneous electron transfer rates for the processes involved for disproportionation rates spanning the entire domain. As clearly indicated, and for certain values of these parameters, the plots display the same type of curvature as those reported in the literature. Shown in Panel B of the Figure are curves for a fictitious set of parameters which were deliberately chosen to obtain a curvature equal in magnitude but opposite in direction. Several methods are currently being considered in order to measure independently the rates of peroxide disproportionation for the same type of rotating disk electrodes used for collecting data of the type discussed herein3.

Acknowledgments

This work was supported by a grant from NSF, CHE-1412060

References

1. S. J. Amirfakhri, J.-L. Meunier and D. Berk, Electrochimica Acta, 114, 551 (2013).

2. E. R. Vago and E. J. Calvo, Journal of Electroanalytical Chemistry, 339, 41 (1992).

3. A. Muthukrishnan, Y. Nabae, T. Okajima and T. Ohsaka, ACS Catalysis, 5, 5194 (2015).

Figure 1
The CO Induced the Deposition of Hightly Ordered Pt Monolayer on Au(111) Electrode and Its Electrocatalytic Properities
Authors: Liao Weicheng , Yau Shuehlin 
Published: February 2020

In situ scanning tunneling microscopy (STM) was used to examine the ordered microstructures of platinum (Pt) deposited on Au(111) substrate in aqueous Na2PtCl6 solution saturated with carbon monoxide (CO) without potential control at room temperature. PtCl6
2- complexes were reduced by CO molecules and deposited on Au(111) in a hexagonal array without potential control. At the same time, we introduced electron spectroscopy for chemical analysis (ESCA) to prove the Pt adatoms were reduced to metallic state after the CO was oxidized in air. According to the results of CV and STM, the coverage of Pt on Au(111) substrate increased sharply with the time passed initially and finally had the value of 0.87monolayer (ML) after 200min dosing. After 5min dosing, the adsorption of CO molecules first mobilized and rearranged Pt adatoms on Au(111) from disordered Pt aggregates to 0.9 nm wide tortuous stripes, and finally to patches of ordered Pt adatoms at 0.1 V (versus reversible hydrogen electrode) in 0.1M H2SO4 saturated with CO. However, the Pt adlayer seem to be too stable to be observed any change with time after 10min dosing. Deposition of Pt in the presence of CO ceased with a monatomic Pt film capped with CO molecules arranged in a (2 × 2) array in both with and without potential control. The CO monolayer adsorbed on Pt/Au(111) was stripped off at 0.96 V in 0.1 M H2SO4, as compared with 0.83 V observed with Pt(111). The E1/2 potential for oxygen reduction reaction (ORR) observed with the Pt-modified Au(111) electrode was 0.81 V in 0.1M sulfuric acid, which is 0.16 V more positive than that of Pt(111). The microstructures of the as-prepared Pt monolayer on Au(111) changed with potential cycling between 0.05 and 1.0 V.

Figure 1
Construction of Non-Enzymatic Hydrogen Peroxide Sensors By Exploiting the High Electrocatalytic Activity of Pd-Ag/Rgo Nanocomposites
Authors: Uzunoglu Aytekin , Song Siyi , Stanciu Lia 
Published: February 2020

The detection of hydrogen peroxide (H2O2) plays a key role in various applications including food and environmental analysis, industrial manufacturing, pharmaceuticals, and biochemistry. Besides, the level of H2O2 in aerobic cells is used to diagnose some pathological conditions ranging from diabetes and Alzeimer’s disease to cancer. Therefore, the construction of H2O2 biosensors with high sensitivity and selectivity have attracted great deal of interest in the last couple of decades. Although there are various analytical methods to detect H2O2, such as photometry, chemiluminescence, chromatography, titrimetry, and colorimetry, electrochemical detection of H2O2 is considered one of the most promising techniques due to its high sensitivity, selectivity, and simplicity. In this work, we designed novel electrochemical non-enzymatic H2O2 sensors by exploiting the high surface area and fast electron transfer rate of reduced graphene oxide (RGO), as well as the high electrocatalytic activity of palladium-silver nanoparticles which were used to decorate RGO. The Pd-Ag/RGO nanocomposites were synthesized using a one-step reduction technique. The prepared metal nanoparticle-decorated RGOs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) techniques. Electrochemical H2O2 sensors were constructed by casting a certain amount of nanocomposite/dimethylformamide solution on glassy carbon electrodes and subsequent drying at room temperature in air. The analytical performance of the sensors was evaluated by cyclic voltammetry and chronoamperometry methods. The preliminary results revealed that Pd-Ag/RGO sensors had higher electrocatalytic activity towards the reduction of H2O2 compared to Pd/RGO and Ag/RGO sensors. The sensitivity of Pd-Ag/RGO sensors to the reduction of H2O2 was found to be -243 µA mM-1 cm-2 at the working potential of -500 mV (vs. Ag/AgCI). In addition, the Pd-Ag/RGO-based sensors yielded a linear analytical response up to 30 mM.
Lithium Biphenyl-3,3',4,4'-Tetracarboxylate Based Anode Material for Li and Na-Ion Battery Application
Authors: Veerababu Medabalmi , Varadaraju U V , Ramanujam Kothandaraman 
Published: February 2020

Li-ion batteries (LIBs) contribute prominently to the energy storage field due to their acceptable cyclibility and higher energy density [1]. However the traditional inorganic based electrode materials suffering due to the constraint imposed by their structural aspects and scarcity of resources. Hence the focus is on the alternative electrode materials which could be synthesized from renewable sources via eco-friendly processes [1,2]. Recently redox active conjugated carbonyl compounds have gained great attention due to their structural diversity, rate capability and ease of synthesis [1]. In this context we report, lithium biphenyl-3,3',4,4'-tetracarboxylate (Li4-BPTC) as a potential anode for both Li-ion and Na-ion batteries for the first time. Li4-BPTC electrode delivered a stable capacity and as well as good rate performance in both Li and Na half cells. Reversible capacities of 92 mAh g-1 after 100 cycles (vs. Li+/Li) and 107 mAh g-1 after 200 cycles (vs. Na+/Na) were observed at a current density of 160 mA g-1. The exchange of Li-ion in the Li4-BPTC by Na-ion during electrochemical cycling against Na+/Na was confirmed by ICP-OES and XPS analysis.
References:

Song Z, Zhou H. Towards sustainable and versatile energy storage devices: an overview of organic electrode materials. Energy Environ Sci., 2013 (6) 2280-301.

Renault S, Brandell D, Gustafsson T, Edström K. Improving the electrochemical performance of organic Li-ion battery electrodes. Chem Commun., 2013 (49) 1945-7.

Figure 1
Functionalization of Carbon with Manganese Oxide for Enhanced Wettability and Capacitance in Neutral Aqueous Electrolyte
Authors: Grewal Simranjit , Read Brandon , Lee Min Hwan 
Published: February 2020

Supercapacitor is one of the most promising energy storage devices to meet surging demands of high-power supply and long-cycle life. Aqueous electrolytes are advantageous over organic electrolytes due to its low cost, safety and ease of assembly but have a major drawback of low energy density due to their small potential windows (~1.2 V). While neutral water is preferred over its acidic or alkaline counterpart to mitigate the drawback (i.e. small potential window), its wettability on carbon, the usual supercapacitor electrode material, has significant room to improve. To address this issue, we considered the incorporation of a metal oxide, MnOx, to the carbon-based structure. MnOx is chosen due to its superior pseudocapacitive capability, wider electrochemical potential window, abundance, and low cost.
In this study, we functionalized active carbon-based structures with a metal oxide (MnOx) by electro-pulse deposition to improve both the electrode wettability and pseudocapacitance. Pulse deposition is chosen to afford a precise control over coating thickness and surface chemistry by controlling the pulse amplitude (0.5 – 3 V), duration (1 – 500 ms) and number of pulsing process. Results showed that there is an optimum in the resulting capacitance; electrodepositing of MnOx at 1 V for 50 ms showed the best performance by improving the overall specific capacitance by 30%. However, the higher pulsing amplitude/duration generally improved wettability. A series of observations indicates that the overall capacitance is co-limited by multiple factors including wettability, surface area and area-specific pseudocapacitance.
Modification of Hierarchical CNT Honeycomb Structures with Fe2O3 for Li-Ion Battery Anodes
Authors: Jessl Sarah , Copic Davor , De Volder Michael F. L. 
Published: February 2020

Carbon nanotubes (CNTs) are attractive additives for battery electrodes because of their excellent electrical and thermal conductivity. However, these properties typically degrade by an order of magnitude in assemblies of CNTs compared to the properties measured in individual CNTs. This discrepancy can be bridged by aligning CNTs into yarns, sheets, or vertically aligned forests. In our work, we study aligned CNTs organized in micro-scale honeycomb structures which are desirable due to their mechanical robustness, conductivity, and high surface area. Because of their mechanical robustness, their surface chemistry can be modified to design battery electrodes.
Here we focus on developing Li-ion battery anodes with a well-defined honeycomb morphology. These honeycombs are fabricated using chemical vapour deposition of CNTs from lithographically patterned catalyst particles. The grown CNTs are subsequently compacted using an elasto-capillary self-aggregation process and thus shaped into honeycomb patterns with varying cell diameters. These electrodes are tested and compared against unaligned CNT powders decorated with the same active nanoparticles, i.e. Iron(III)-Oxide (Fe2O3). The influence of the cell sizes and aspect ratios on the electrode performance is measured after the decoration with Fe2O3 as an active material.

Figure 1
Single-Walled Carbon Nanotubes (SWCNTs) for Protein Engineering Applications
Authors: Wu Shang-Jung , Zubkovs Vitalijs , Boghossian Ardemis Anoush 
Published: February 2020

Protein engineering is a technique that has allowed researchers to overcome billions of years of evolution to create unnatural proteins that have been re-programmed to function and interact in ways unfounded in nature. It has been used to engineer proteins for a breadth of new purposes. This technique allows researchers to change the function of the protein by modifying its structure. Though a theoretical understanding of the relationship between the protein structure and function is helpful, unfortunately, the structure-function relation in the vast majority of proteins remains unknown. Directed evolution is a powerful protein engineering method that circumvents the need to define the structure-function relation of a protein. Briefly, after introducing random mutations to the protein, the collection of mutated proteins is screened to identify proteins with the new, desired function. The proteins with beneficial mutations are then isolated and mutated once more, and the process is repeated until the new protein function has been optimized. Scientists use this strategy to modify and/or improve protein properties, including stability, fluorescence, activity, and affinity to a specific target. One primary challenge in this method is developing a high-throughput screen for evaluating protein function. Researchers have established several high-throughput techniques to screen protein activities effectively using, for example, fluorescence-activated cell sorting or in vitro compartmentalization. However, these methods are largely limited to specific proteins and cannot be readily generalized.
In our work, we use single-walled carbon nanotubes (SWCNTs) in a novel platform for investigating the functionality of a protein. SWCNTs emit fluorescence in the near-infrared spectral region between 900 nm and 1500 nm, a region that lies outside the optical window of most proteins and biomaterials in general. Further, SWCNTs demonstrate single-molecule sensitivities, with fluorescence emissions changing in response to perturbations in the charge, dielectric constant, and pH of the environment. We have exploited this sensitivity by interfacing SWCNTs with proteins that induce local environmental changes when active, thus allowing us to monitor protein activity by measuring the resulting changes to the SWCNT fluorescence. Combined with a moderate to high-throughput approach for acquiring SWCNT fluorescence, this platform provides biologists with a new tool for expediting the protein discovery process and engineering previously intractable proteins.