bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced Long-Term Cycling Performance of Single Crystalline LiCo0.95Ni0.05O2 cathode Material at High Cut-Off Voltage in Li-Ion Cell
Authors: Yoon Moonsu , Cho Jaephil 
Published: February 2020

A significant interest in developing high volumetric energy density and high power energy storage systems (ESSs) has facilitated development of ideal cathode material in Lithium-ion batteries. Among various cathode materials, LiCoO2 (LCO) is one of the promising candidates because of single crystalline morphology with relatively high electrode density (>3.9g cm-3) and superior electrochemical performance. However, Increased cut-off voltage, higher than the conventional operating voltage of LCO (~4.3 V vs. Li/Li+), to maximize energy storage capacity gives rise to severe electrochemical degradation at the electrode-electrolyte interface and irreversible structural deformation at highly delithiated states of cathode material, which result in a rapid decrease of capacity and nominal voltage in a continuous cycle.
Herein, for an enhanced cycle life of LCO particularly in high cut-off voltage, we proposed LiCo0.95Ni0.05O2 (LCNO) which not only enabled to demonstrate remarkable cycling performance and but also to be synthesized as a single crystalline with layered structure(R-3m) by the solid-state method in air condition. For comparison, the electrochemical behaviors of active materials, LCO and LCNO, charged up to 4.45V, were investigated. Even though LCO showed an initial reversible capacity of ∼182 mAh/g, higher than that of LCNO (∼176 mAh/g), LCNO exhibited much better capacity retention of 93.6% than that of LCO (74.3%) under continuous 100 cycles. We identified the less formation of irreversible byproducts on the surface of LCNO, compared to that of LCO, indicating the reactivity of interface between LCNO-electrolyte was highly stabilized with the assistance of Ni-ions. Furthermore, the evolution of interfacial change between LCNO-electrolyte after electrochemical cycling has been also investigated by high-resolution scanning transmission electron microscopy (HR-TEM). Based on electron energy-loss spectroscopy measurements (EELS), we confirmed that Ni-ions in LCNO may have a potential ability to initiate the oxidation state of Co ions around the surface to be partially reduced to Co2+/Co3+ mixed-valence state during cycles with a change of surface structure from layered structure to spinel-like phase, thus reducing surface side reaction simultaneously.
High Performance Anion-Exchange Membranes and Ionomers for Use in Alkaline Membrane Fuel Cells
Authors: Wang Lianqin , Ponce Gonzalez Julia , Bance-Soualhi Rachida , Whelligan Daniel , Varcoe John 
Published: February 2020

This presentation will describe the latest research at the University of Surrey on the development of high-performance anion-exchange membranes (AEM) and ionomers (AEI) for use in alkaline membrane fuel cells (AEMFC). These anion-exchange polymer electrolyte matreials are produced using the peroxidation pre-irradiation grafting method (RG).
Recent achievements that will be discussed in this presentation include:

Synthesis of RG-AEMs with new chemistries that are more stable to alkali than those containing the benzyltrimethylammonium benchmark;

The ability to produce RG-AEMs based on low density polyethylene (LDPE) as well as poly(ethylene-co-tetrafluoroethylene) (ETFE);

Synthesis of thinner AEMs (< 30 μm thickness);

Synthesis of an interesting class of RG-based solid-state AEI powders;

AEMs with high hydroxide conductivities and high performances in hydrogen-fuelled AEMFC;

Advanced use of Raman micro-spectroscopy for studying radiation-grafted anion-exchange polymer electrolytes.

We will demonstrate that changes in head-group chemistry can switch off several alkali degradation mechanisms for RG-AEMs. We will also show that 2 W cm-2 peak power densities can be achieved in H2/O2 AEMFCs containing Pt cathodes and > 1 W cm-2 can be achieved with non-platinum-group-metal cathodes. The figure below shows the performance of a thin ETFE-based RG-AEM in H2/O2 and H2/air(CO2-free) AEMFCs when Ag/C cathode is used as a cathode electrocatalyst.

Figure 1
The Micro-Optical Ring Electrode: A Sensor for Multiple Actinide Ions Monitoring
Authors: Linnett Gary 
Published: February 2020

We present on the development of the Micro-Optical Ring Electrode (MORE) for the analysis of trans-uranium elements in aqueous mixtures. The MORE is a photo-electrochemical device based on a ring microelectrode that uses the insulator interior to the ring as a light guide. This single device exploits the unique photophysical and electrochemical properties of multiple analytes present in mixtures to quantify them. Our study aims to develop a protocol for the analysis of ions of uranium, neptunium and plutonium, which are most relevant to the nuclear industry, especially in the areas of decommissioning and fuel reprocessing, where speedy and safe identification of radioactive contaminants is essential.
The technique offers a number of advantages over traditional methods in the area of radiochemical analysis such as real time monitoring in-situ, reduced radiation dose impact to the analyst as a result of greatly reduced sample handling and preparation, improved analysis times allowing quick decision making, at a much reduced cost (e.g. compared to ICP-MS and Scintillation counting).
Optimizing Surface Modifications for Quantum Dot Labelled DNA SAMs Using Electrochemistry Coupled Fluorescence Imaging
Authors: Sundar Rochita , Bizzotto Dan 
Published: February 2020

Electrochemical biosensors are being developed for detecting specific sequences of nucleic acids using DNA modified gold surfaces[1]. A single crystal gold bead electrode was used to study the arrangement on DNA on different gold surfaces[2]. The gold surface was prepared with a mercaptoundecanol (MUDOL) self-assembled monolayer (SAM). Using a specific desorption potential of -0.850 V/SCE, the MUDOL was reductively desorbed from the Au(111) facet. The defects in the SAM were passivated with a shorter alkylthiol, mercaptohexanol. Thiol modified DNA which is also labeled with a fluorophore was allowed to populate the 111 facet specifically. This was studied using fluorescence microscopy coupled with electrochemical control. A fluorescence image of the gold bead (Figure a) showed that only the 111 facets were modified. The density of the DNA modification was also evaluated using the reorientation of DNA based on the electrode charge density. At positive potentials the DNA was positioned close to the electrode and the fluorescence was quenched. At negative potentials the DNA was repelled and the fluorescence increased. This change in fluorescence is indicative of the density of DNA on the surface. The same approach will be used to assemble DNA modified Quantum Dots (QDs) onto the Au(111) facets. A complementary ssDNA was attached to a glutathione capped quantum dot vis a his-tag peptide. The QD labelled ssDNA was allowed to hybridize with the ssDNA on the gold electrode. Figure (b) is the cartoon depiction of such a layer. Recent research results will be described on the characterization of QD labelled DNA SAMs. The QDs due to their broad absorption and narrow emission spectrum also offer the advantage of building more complicated multiplexed systems in future.
(1) Hsieh, K.; Ferguson, B. S.; Eisenstein, M.; Plaxco, K. W.; Soh, H. T. Integrated Electrochemical Microsystems for Genetic Detection of Pathogens at the Point of Care. Acc. Chem. Res.
2015, 48, 911–920.
(2) Yu, Z. L.; Casanova-Moreno, J.; Guryanov, I.; Maran, F.; Bizzotto, D. Influence of Surface Structure on Single or Mixed Component Self-Assembled Monolayers via in Situ Spectroelectrochemical Fluorescence Imaging of the Complete Stereographic Triangle on a Single Crystal Au Bead Electrode. J. Am. Chem. Soc
2015, 137, 276–288.

Figure 1
Electrowetting of Liquid Drops Revisited By XPS
Authors: Aydogan-Gokturk Pinar , Ulgut Burak , Suzer Sefik 
Published: February 2020

Electrowetting behavior of liquid drops has been followed in-situ and in-vacuum using XPS in a chemically resolved fashion, under both D.C. and A.C. excitations. Various liquid drops, compatible with the UHV conditions, consisting of an Ionic Liquid, DEME-TFSI, [N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide]), or Poly-Ethylene-Glycol (PEG, M.W. ~600 amu) and their mixtures. For the dielectric substrate, a ~300 nm thick silicon oxide (SiO2/Si) without and with a thin (~20 nm) hydrophobic amorphous fluoropolymer coating, CYTOP (Bellex International Co.), has been employed. XPS data have been recorded both in the conventional scan and also in the fast (<1s) snap-shot modes. Intensity and position of the peaks, representing the liquid drops (F1s in the case of the IL, or C1s/O1s of the PEG) as well as those of the substrates (Si2p for the oxide only and F1s for the hydrophobic coated one) have been recorded under various electrical excitations. Under AC excitation at a fixed frequency, intensity modulations in the XPS peaks reveal geometrical changes of the drops, while the peak position modulations reveal electrical potentials developed. Monitoring binding energy modulations as a function of the changes in the AC frequency (10-2 – 104 Hz) allows us tap into ionic, dipolar and electronic contributions of the dielectric susceptibility of both the liquid drops and the substrates. Experimental details and various applications will be presented and discussed.
This work is partially supported by TUBITAK through Grant No. 215Z534
Transport & Charge Transfer Near Electrochemical Interfaces: A Quasi-Fermi Perspective
Authors: Grew Kyle N. 
Published: February 2020

Theories describing the electrochemical double layer have long presented challenges to researchers, yet remain important understanding electrochemical processes. Many of these challenges stem from the multiscale nature of electrochemical interfaces where excess carrier concentrations, whether ions in electrolytes or electrons/holes in semiconductors, can extend 10s of nanometers into the bulk. It is expensive and difficult to capture the full interface with atomistic methods whereas continuum-level mean field approaches often face issues with adequately capturing steric and other physiochemical aspects of the carriers. In both cases, there are issues with the definition of potentials which are experimentally relevant and self-consistent with the associated effects on the participating media [1].
Nevertheless, numerous physiochemical effects that include but are not limited to specific adsorption, dielectric decrement, specific adsorption, osmotic pressures, solvent mixing, and ionic correlations have been identified and described [1-3]. And corrections to mean field theories, such as through the perturbation for finite sized ions, have been put forth to improve predictability [4-6].
In this talk, a quasi-Fermi perspective on transport and space charge near interfaces will be presented. The approach put forward simplifies analysis for electrolytic solutions including for transport at dissimilar interfaces. A perspective on the potential scale and ties to absolute electrode potentials will be presented. The approach will be demonstrated with bipolar membrane electrolyte and photoelectrochemical conversion interfaces.

References

[1.] A. Baskin and D. Prendergast, Improving Continuum Models to Define Practical Limits for Molecular Models of Electrified Interfaces, J Electrochem Soc
164 (2017), E3438-E3447.
[2.] D. Ben-Yaakov, D. Andelman, D. Harries and R. Podgornik, Beyond standard Poisson-Boltzmann theory: ion-specific interactions in aqueous solutions, J Phys-Condens Mat
21 (2009).
[3.] D. Ben-Yaakov, D. Andelman and R. Podgornik, Dielectric decrement as a source of ion-specific effects, J Chem Phys
134 (2011).
[4.] M. S. Kilic, M. Z. Bazant and A. Ajdari, Steric effects in the dynamics of electrolytes at large applied voltages. II. Modified Poisson-Nernst-Planck equations, Phys Rev E
75 (2007).
[5.] M. S. Kilic, M. Z. Bazant and A. Ajdari, Steric effects in the dynamics of electrolytes at large applied voltages. I. Double-layer charging, Phys Rev E
75 (2007).
[6.] M. Z. Bazant, Theory of Chemical Kinetics and Charge Transfer based on Nonequilibrium Thermodynamics, Accounts Chem Res
46 (2013), 1144-1160.
(Invited) Magnetoelectrocatalysis of Oxygen Reduction Reaction (ORR) By Lanthanide Triflates in Acetonitrile
Authors: Knoche Krysti L. , Parr Daniel , Leddy Johna 
Published: February 2020

Lanthanides have sufficiently similar chemical and physical properties that lanthanides are difficult to separate. Among the common properties are standard potentials that fall within 100 mV for Ln3|0. The standard potentials are sufficiently extreme that lanthanide electrochemistry is commonly undertaken in ionic liquids and molten salts. Recently, it was demonstrated that cyclic voltammetry of lanthanide triflates is accessible in acetonitrile at Nafion modified electrodes. Because at least four different oxidation states of the lanthanides are accessible, the voltammetric response is complex, as demonstrated by fitting the mechanism.
Interest in benchtop electrochemistry of lanthanides arose from investigations of magnetoelectrocatalysis, where magnetic properties and spin impact rates of electron transfer at electrodes and electrocatalysts. Despite largely similar properties, lanthanide magnetic properties are diverse because the number of unpaired electrons in the d orbitals ranges from 0 to 7. The presence of lanthanides at the electrode surface mediates rates of important reactions that include the oxygen reduction reaction (ORR).
Ytterbium triflate extracted into Nafion on electrode in acetonitrile increase oxygen reduction currents by 15%. On introduction of electrochemically inert hematite microparticles into Nafion, oxygen reduction currents are enhanced 35%. Other measures of catalysis that include decreased overpotential are also observed.
Reference
Johna Leddy and Krysti L. Knoche, Lanthanide Electrochemistry, published 12 November 2015 as US Patent Application, 20150322581-A1
Active Non-Precious Metal Based Nitride Catalysts for the Oxygen Reduction Reaction
Authors: King Laurie Ann , Kreider Melissa , Siahrostami Samira , Back Seoin , Jaramillo Thomas F 
Published: February 2020

Proton-exchange membrane fuel cells (PEMFC) that convert chemical energy from a fuel into electricity offer a promising route for decarbonisation of both the electricity and transportation sector. Today, platinum-based catalysts are the most active and widely implemented catalyst for both the oxidation and reduction reactions in a PEMFC. However, concerns regarding the scarcity and high costs associated with platinum motivate the search for alternative active and stable catalysts.1 In particular at the cathode, the sluggish oxygen reduction reaction (ORR) kinetics requires a high loading of platinum. Thus, new non-platinum group metal based catalysts are necessary to reduce the cost of PEMFC technologies.
One class of materials that has attracted recent attention for ORR in acidic media are the nitrides. In particular, hexagonal boron nitride (h-BN),2 and transition metal nitrides have shown excellent activity and promising stability ORR catalysts.3 In this work we investigate the ORR activity and stability of non-precious metal nitride catalysts as a function of synthesis technique, morphology and chemical composition. Alloying and doping the nitride catalysts, as well as probing the role of substrate identity are investigated. We compare our electrochemical data with computationally investigated ORR activity using density functional theory (DFT) calculations.

References

(1) Seh, Z. W.; Kibsgaard, J.; Dickens, C. F.; Chorkendorff, I.; Nørskov, J. K.; Jaramillo, T. F. Science (80-. ).
2017, 355 (6321), eaad4998.
(2) Uosaki, K.; Elumalai, G.; Noguchi, H.; Masuda, T.; Lyalin, A.; Nakayama, A.; Taketsugu, T. 2014, 136 (111), 6542.
(3) Cao, B.; Neuefeind, J. C.; Adzic, R. R.; Khalifah, P. G. Inorg. Chem.
2015, 54 (5), 2128.
Melamine-Sponge-Derived Fe-N/C Electrocatalyst with Tunable Pore Structure and Nitrogen Chemical State for Exceptional Oxygen Reduction Reaction
Authors: Xia Dongsheng , Gan Lin 
Published: February 2020

Developing economic and highly active non-precious metal electrocatalysts for oxygen reduction reaction (ORR) is critical for the development of hydrogen fuel cells. While several nitrogen-carbon precursors have been explored, only limited systems such as phenanthroline-based catalyst after pyrolysis in NH3, polyaniline- and/or cyanimide-derived catalysts, Zn-based metal-organic frameworks (MOF), or a combination of the above precursors were reported to derive highly active Fe-N/C catalysts. It is still challenging to concurrently achieve high density Fe-N4 active sites with optimized local Fe-N/C environment, high microporous surface area, and rational macro-/meso-pore structures at an economic cost. For instance, although MOF-derived Fe-N/C catalysts have shown exclusive high density single Fe atoms confined in the N-doped microporous carbon, the lack of mesopores may limit their ORR performance. In addition, MOF-derived catalysts also suffered from its relatively high cost, hindering their large-scale applications.
We report here a novel melamine-sponge-derived Fe-N/C catalyst with exceptional ORR electrocatalysis by virtue of their simultaneously tunable hierarchical micro-/meso-/macro-porous structure and nitrogen chemical state. The melamine sponge serves as a promising and low cost carbon precursor for hosting Fe-N active sites upon NH3 pyrolysis, showing (i) increasing mesopores for favorable mass transport while keeping a high microporous surface area and (ii) increasing pyridinic nitrogen surrounding the Fe center with increasing pyrolysis time. The optimum Fe-N/C catalyst shows high ORR activity particularly in alkaline media with a half-wave potential of 0.902 V/RHE and mass activity of 15.0 A/g at 0.9 V/RHE, markedly outperforming commercial Pt/C and most non-precious metal catalysts to date. Considering the low cost and industrial scalability of the MS precurosr, the MS-derived Fe-N/C catalysts are expected to be a promising candidate as non-precious fuel cell electrocatalyts.
Durability of Pt/C with Different Nitrogen for Contents for Oxygen Reduction Reaction in PEMFC
Authors: Ham Kahyun , Lee Jae Kwang , Lee Jaeyoung 
Published: February 2020

To meet a worldwide demand about the supply of sustainable energy and solve the environmental problems, Polymer electrolyte membrane fuel cell (PEMFC) is one of the promising energy conversion technologies which can be utilized in various industrial fields. Among the components of PEMFC, Pt nanoparticle on carbon (Pt/C) have been intensively studied as a catalyst for oxygen reduction reaction. However, the state-of-art Pt/C cannot meet the requirement for the long-term operation in PEMFC system owing to both Pt dissolution and sintering/particle growth on carbon support. In a view of strengthening interaction between Pt and catalyst support, the use of highly graphitic carbon and S, N-doped carbon could be reasonable approach.
In this study, we investigate the effect of nitrogen contents of carbon support for Pt catalyst in terms of MEA durability. N-doped carbon is provided by ball-milling with pristine carbon and melamine. To designate N contents and investigate surface structure, transmission electron microscopy, X-ray diffraction and Raman spectroscopy are carried out. To understand electron transfer between Pt and N, we conduct X-ray absorption fine spectroscopy and X-ray photoelectron spectroscopy. The synthesized Pt/N-C via polyol process shows improved performance toward oxygen reduction reaction in acidic media than commercial Pt/C.
Electrochemical Deoxygenation of Aqueous Solutions Using Symmetric Activated Carbon Electrodes in Flow-through Cells
Authors: Holubowitch Nicolas , Landon James , Gao X. , Liu K. , Omosebi A. 
Published: February 2020

We present a simple electrochemical flow cell using symmetric, unmodified commercially available carbon cloth electrodes that removes 97+% of incoming aqueous dissolved oxygen (DO). The electro-deoxygenation (EDO) cell achieves net O2 removal by leveraging the high overpotential of the oxygen evolution reaction on activated carbon and its propensity to oxidize under anodic polarization in aqueous solution: oxygen is reduced at the cathode via the oxygen reduction reaction (ORR) while water is oxidized and incorporated into surface oxide functional groups at the anode, effectively sequestering dissolved oxygen. The polarized electrodes promote the two-step reduction of DO resulting in some residual hydrogen peroxide in the effluent, which may be beneficial for certain water treatment applications. We modified a cell with Ni cathodes downstream to reduce all H2O2 to water for particularly sensitive applications; in this cell >99% of incoming DO could be removed to sub-10 ppb levels. EDO cells, which currently employ sacrificial anodes, can deaerate 30 L g-1
anode of water at an energy cost of 1 kWh (~$0.10) per 104 L. The technique is versatile, successfully deoxygenating solutions from dilute to seawater concentrations and at flow rates beyond 50 ml min-1 (O2 flux = 10-4 mol s-1 m-2), more than 50x higher throughput DO removal than similar technologies. We demonstrate the utility of an EDO cell as a component in an electrochemical water desalination process; dissolved oxygen removed upstream of a capacitive deionization cell enhances salt adsorption capacity and cell lifetime.
Figure 1. (a) Dissolved oxygen removal by an electro-deoxygenation cell stack with six pairs of electrodes (up to t = 1.1 h) and subsequently with an additional H2O2 removal stack (six Ni cathodes and two additional anodes electrically connected in parallel downstream, t > 1.1 h). The device is operated by holding the cathodes, connected in parallel, at an oxygen-reducing potential versus an in situ reference electrode to achieve E
c = -0.2 V vs. SHE. The electrolyte is 0.1 M NaCl with an initial flow rate of 50 ml min-1, and the effect of increasing flow to 75 and 100 ml min-1 is shown at t > 4.2 h. (b) Salt removal performance of a capacitive deionization (CDI) cell downstream of our EDO cell; the electrolyte is 10 mM NaCl flowing at 20 ml min-1 and the CDI cell consists of four pairs of carbon cloth electrodes totaling 3.2 g with charging/discharging at V
cell = 1.2/0.0 V in a single-pass mode. At t = 24 h, the EDO cell is turned off to highlight its effect on deionization performance.

Figure 1