bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanoscale Engineering of Efficient Oxygen Reduction Electrocatalysts By Tailoring the Local Chemical Environment of Pt Surface Sites
Authors: Linic Suljo 
Published: February 2020

The oxygen reduction reaction (ORR) is the major source of overpotential loss in low-temperature fuel cells. Expensive, Pt-based materials have been found to be the most effective catalysts, but exploration of alternatives has been hampered by stability constraints at the typical operating conditions of low pH and high potential.
I will discuss our studies of elementary mechanism of ORR on various metal electrodes using kinetic and micro-kinetic analysis of reaction pathways and quantum chemical calculations. These studies allowed us to identify the elementary steps and molecular descriptors that govern the rate of ORR. Using these performance descriptors we have been able to identify families of Pt and Ag-based alloys that exhibit superior ORR performance is acid and base respectively.
We have synthesized these alloys to demonstrate the superior ORR activity with rotating disk electrode experiments. We have also performed thorough structural characterization of the bulk and surface properties with a combination of cyclic voltammetry, x-ray diffraction, and electron microscopy with spatially resolved energy-dispersive x-ray spectroscopy and electron energy loss spectroscopy.

Xin, H.; Linic, S., J. Chem. Phys. 2016 144 (23), 234704

Van Cleve T, Moniri, S, Linic, S, 2016, ACS Catalysis 7 (1), 17-24

Moniri S., Van Cleve T., Linic S., Journal of Catalysis 345, 1-10

Holewinski and Linic. J. Electrochem. Soc. 159, (2012).

Adam Holewinski, Juan-Carlos Idrobo, Suljo Linic. Nature Chemistry
,
6, 828-834, 2014.
Defect Chemistry and Lithium-Ion Transport in Doped Li2ZrO3: The Role of Oxygen Vacancies
Authors: Zhan Xiaowen , Shirpour Mona , Cheng Yang-Tse 
Published: February 2020

Lithium zirconate (LZO) is an attractive material for many applications. For example, it has been extensively studied as a solid absorbent for reversible CO2 capture at elevated temperatures, as a ceramic breeder for nuclear reactors, and as a coating for high-capacity cathode materials in lithium ion batteries (LIBs).
The Li+ transport is critical to the functionality of LZO in these applications. For CO2 adsorption, Li+ diffusion is a critical factor affecting both surface absorption and high-temperature CO2 desorption processes. For LIBs, LZO can provide fast migration pathways for Li+ at the electrolyte-electrode interface when it is used as a coating for electrodes. For nuclear fusion, the Li+ migration through vacant sites inside LZO grains is closely related to its performance in tritium (3H) release. Therefore, understanding the Li+ migration mechanism and, more importantly, enhancing Li+ transport in LZO is important to many applications.
Control of dopant concentration is an effective way to tune the Li+ conductivity. However, the electrical conductivity of doped LZO and the relationship between defect chemistry and electrical conductivity in doped LZO have not been reported. In addition, the effect of oxygen concentration on Li+ diffusion has not been fully understood. Here, we study the defect chemistry and electrical properties of the undoped LZO and a series of cation-doped LZO samples. We establish a relationship between Li+ conductivities and doping-induced oxygen/Li nonstoichiometries. We demonstrate that the conductivity results can be understood by unveiling the critical role of oxygen vacancies in Li+ transport. An improved CO2 absorption performance of doped LZO materials will also be discussed.
Dielectric and Ferroelectric Properties of Rare Earth Doped Lead Zirconate Titanate Ceramics
Authors: Bhattarai Mohan K , Pavunny Shojan Pullockaran , Instan Alvaro A , Katiyar Ram S 
Published: February 2020

We have synthesized La3+ and Sc3+ doped lead zirconate titanate electroceramics with the stoichiometric formula ( (PLZTS), where x = 0.1 and y = 0.2, 0.4, 0.6 & 0.8, by a conventional solid-state reaction method & investigated its structural, microstructural, dielectric, electrical and ferroelectric properties. X-ray diffractometry was used to probe the phase purity and to derive the crystallographic parameters. Furthermore, structural phase transition was investigated by analyzing Raman spectra recorded in the temperature window of 80-580 K. The size, shape, and the distribution of grains were examined through a scanning electron microscope (SEM) and the sample was subjected to energy dispersive spectroscopy (EDS) for elemental analysis.
We have carried out dielectric and electrical measurements on Pt/PLZTS/Pt metal-ferroelectric-metal capacitors using impedance analyzer and electrometer, respectively, as a function of temperature (100-600 K) and frequency (102-106 Hz). High dielectric constants (ɛ’) ~280, ~500, ~1800 & 1000 for y = 0.2, 0.4, 0.6 & 0.8 respectively were observed at room temperature. We measured hysteresis loops which proved the existence of ferroelectricity in all prepared samples of different compositions. These results provide insights into PLZTS ferroelectric capacitor for its potential applications in the future electronic devices.
Electrochemical Responses of Graphene with Biofilm Formation on Various Metallic Substrates By Using Laboratory Biofilm Reactors
Authors: Kanematsu Hideyuki , Shindo Kodai , Barry Dana M. , Hirai Nobumitsu , Ogawa Akiko , Kuroda Daisuke , Kogo Takeshi , Ikegai Hajime , Mizunoe Yoshimitsu 
Published: February 2020

We have confirmed that graphene is very sensitive to biofilm formation by environmental biota and by some special bacteria (E.coli and S.epidermidis). Therefore, graphene is not recommended for biomaterials used in the human body. Graphene’s high sensitivity could lead to infections. On the other hand, this high sensitivity might allow grapheme to serve as a sensor for detecting biofilm formation at a very early stage. To obtain more data, we investigated the change of electrochemical responses for graphene on various substrates (while biofilms were forming on these samples).
Biofilms were formed on metallic substrates. The procedure is briefly described. A mechanical exfoliation method was repeated by using scotch tape. For each final stage, the graphene on the scotch tape was transferred to the surface of a metallic sheet-type specimen. (Various specimens were used.) The graphene formed on the metallic specimens was confirmed by using Raman spectroscopy and by staining. For the staining, 0.1% crystal violet was used. We expected that the extent of graphene formation would increase with the repeated number of attachments between tapes. Therefore, some transferred specimens, with different repeated numbers than others, were prepared as specimens. Then they were immersed in culture liquids (LB culture liquids and HI ones) including E.coli and Staphylococcus epidermidis.
The specimens were also immersed into rotational-type reservoirs filled with culture liquids including bacteria. Each specimen was fixed with a special jig and the culture liquids were stirred continuously.
Two laboratory biofilm reactors (a static type and a flow type reactor) were used for this work. Measurements of electrochemical responses (Cyclic voltammetry, immersion potential etc.) were made for all samples, while the changes of Raman shifts with time on those specimens were observed too. Also the final states of the specimens were checked by using crystal violet.
Finally, behaviors were analyzed and the applicability to sensing biofilm formation was discussed.
Graphene Supported Manganese (IV) Oxide Nanoparticles As High-Performance Electrochemical Capacitor
Authors: Jablonskienė Jolita , Šlopšnys Justinas , Pakštas Vidas , Vaičiūnienė Jūratė , Selskis Algirdas , Drabavičius Audrius , Jasulaitienė Vitalija , Tamašauskaitė-Tamašiūnaitė Loreta , Norkus Eugenijus 
Published: February 2020

The search for cleaner energy sources is required to shift focus to the generation of energy from electrochemical systems, batteries and fuel cells, solar cells, and super capacitors, among others. We report a simple one-step approach for microwave-assisted synthesis of manganese oxide nanoparticles deposited on the graphene (MnO2/GR) or carbon (MnO2/C) supports. The MnO2/GR and MnO2/C nanocomposites have been synthesized with different morphologies. The MnO2 nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical performance of the MnO2/GR and MnO2/C nanocomposites was evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge.
It was found that the graphene supported MnO2 nanoparticles has significant influence on the electrochemical performance of composites electrodes compared with that of the carbon supported MnO2 nanoparticles. The maximum specific capacitance of 108 F g-1 was achieved at the MnO2/GR electrode in the 1 M Na2SO4 aqueous solution at the scan rate of 10 mV s-1.

Acknowledgement

This research is funded by the European Social Fund under the No. 09.3.3-LMT-K-712-02-0142 “Development of Competences of Scientists, other Researchers and Students through Practical Research Activities” measure.
High Voltage Spinel LiNi 1/2Mn3/2O4 : Kinetics and Thermodynamics Properties
Authors: Dumaz Philippe , Rossignol Cécile , Bouchet Renaud 
Published: February 2020

In order to increase the energy density of lithium-ion batteries, there are two levels; one is the increase of the specific capacity of both positive and negative active materials (i. e. in Li/S8 technology) and/or the increase of the battery voltage. The most simple solution a promising solution is theo use of positive active materials with high potential (up to 5V vs Li + / Li) [1] because it does not change the technology conception. Among the different materials, The spinel LiNi1/2Mn3/2O4 has a theoretical capacity of 147 mAh/g and a potential of 4.8 V vs Li+/Li, which enable a high energy density [2] (at least 20% more than standard LiCoO2). In the literature, a wide range of values for diffusion coefficient have been reported and only few studies reports values for exchange current density [3,4,5] . This work intended to highlight the impact of thermodynamic factor on the diffusion and to bring new values for the exchange current density, measured by impedance spectroscopy. The study of thin film of spinel LiNi1/2Mn3/2O4 enables to use simplified equations for extracting kinetics and thermodynamics values like exchange current density at the interface of the material, values of the diffusion in the thin electrode and thermodynamic factor that affect the mobility in the structure, depending on the state of charge. These results have then been compared to the ones obtained on composite electrodes. Very and good agreement were obtained even using a 1D model on composite electrodes.
[1] Tarascon et al. Nature Mater. 2011
[2] Yi et al. J. Power Sources, 2016
[3] Aurbach et al. Electrochim. Acta, 2005
[4] Amin et al. J. Power Sources, 2017
[5] Nishikawa et al. J. Electroanal. Chem. 2017
Improving High Rate Electrochemical Performance of Patterned Lithium Metal Anode for Lithium Secondary Batteries By Using Dual Salt Electrolyte System
Authors: Yoon Byeolhee , Kim Seokwoo , Jin Dahee , Park Jinkyu , Oh Jeonghun , Jo Hearin , Choi Junyoung , Ryou Myung-Hyun 
Published: February 2020

Recently, demand for lithium (Li) secondary batteries has been increasing as the market for mid- to large-size batteries such as electric vehicles (EV) and energy storage systems (ESSs) is expanding. Especially in order to popularize EVs, it is essential to improve the energy density in order to secure mileage. However, using commercialized graphite as an anode material is difficult to increase energy density due to their limited capacity. Li metal is an ideal anode material due to its extremely high theoretical specific capacity (3860 mAh g-1), low density (0.59 g cm-3) and the lowest negative electrochemical potential (‒3.040 V vs. the standard hydrogen electrode). For instance, Li/air and Li/S batteries enable to increase dramatically energy density. However, Li metal has been proposed as a problem of deterioration of cell performance due to dendrite caused by charging / discharging process and battery short circuit. More importantly, Li dendrite-growth lead to safety issue, i.e., thermal runaway, causing a catastrophic satety failure accompanied by fire and smoke.
To overcome this problem, many efforts have been devoted to suppress lithium dendrite-growth. Recently, we demonstrated the possibility of using mechanically surface-patterned Li-metal for Li secondary batteries. In our previous work (J. N. Park et. Al), patterned Li-metal anode showed good cycle life at low current density cycling. Still, high current density cycling showed limited cycle life because of bulky Li dendrite formation in the micro-patterned Li-metal holes. These consume more amount of electrolytes during charging/discharging processes.
In this work, we applied dual salt system electrolyte on the micro-patterned Li metal to suppress mechanically bulky Li deposition in the micro-patterned Li-metal holes during charging/discharging processes. And then, their electrochemical properties are investigated in detail.
(Invited) Ion Irradiation Effects on Structural and Electrochemical Charge Storage Properties of Electroceramic Materials for Lithium-Ion Batteries
Authors: Smith Kassiopeia , Savva Andreas , Wharry Janelle , Xiong Hui (Claire) 
Published: February 2020

Lithium-ion batteries are promising battery technologies to provide high energy and high power for applications such as electric vehicles or electrical grids. Recent studies have observed that lithium-ion battery
electrode materials (e.g. TiO2) containing intentional structural defects exhibit enhanced electrochemical charge storage capacity. In this work we investigate the irradiation effect on structure and electrochemical response of TiO2 nanotube electrodes through proton ion irradiation, because irradiation is known to produce an excess of defects in a material. In addition, we investigated heavy ion irradiation on TiO2 single crystals to elucidate the effects of irradiating species and crystallographic orientation on defect production and microstructure evolution. We have observed defect generation upon irradiation in both nanostructured and single crystal TiO2 samples and investigated the relationship between irradiation-induced defects and the electrochemical properties of the TiO2 samples.
Advances in Electron Microscopy Methods to Evaluate Thin Ionomer Layers in PEM Fuel Cell Catalyst Layers
Authors: More Karren L. , Cullen David A. 
Published: February 2020

The ability to characterize the thin ionomer films within the catalyst layers in membrane electrode assemblies (MEAs) at the nm-scale via analytical electron microscopy presents many challenges. The ionomer degrades rapidly during analysis with high-current electron beams, which can be mitigated to some extent when experiments are conducted using higher operating voltages and under cryogenic temperatures.1 These microscopy operational parameters have proven most useful for imaging, mapping, and analyzing ionomer aggregates that are typically tens-to-hundreds of nms in size, have not been particularly useful for understanding the nature of the thin ionomer films that percolate through the thickness of the catalysts layers.
Recently, Oak Ridge National Laboratory has acquired a new aberration-(probe)-corrected analytical scanning transmission electron microscope (STEM) that can be operated under conditions significantly more favorable for interrogating “soft matter” at very high resolution, e.g., structure and chemistry of the nm-scale thin ionomer films within intact catalyst layers. This new STEM, the JEOL-NEOARM, can be operated between 30kV-200kV at low-electron-dose and is equipped with state-of-the-art analytical capabilities for the simultaneous acquisition of electron energy loss spectroscopy (EELS) and energy dispersive X-ray spectroscopy (EDS). Most notably, the new STEM is equipped with a novel pixelated detector that enables ultrafast image/diffraction (ptychographic) data acquisition that will minimize exposure of the ionomer films to the electron beam, preventing damage accumulation, and allowing for complete data reconstruction following data collection.
We will present imaging and spectroscopic results obtained by varying the STEM operating conditions on the NEOARM (voltage, electron dose, sample temperature, ptychographic reconstruction methods) and exploiting its unique combination of ultrafast capabilities. The high-resolution structural and compositional information provided will provide new insight regarding thin ionomer films within MEA catalyst layers
Research supported by the Fuel Cell Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy, as part of the Fuel Cell Performance and Durability (FC-PAD) Consortium. Microscopy research performed as part of a user project at the Center for Nanophase Materials Sciences, which is a U. S. Department of Energy, Office of Science User Facility.

References

D.A. Cullen, R. Koestner, R.S. Kukreja, Z.Y. Liu, S. Minko, O. Trotsenko, A. Tokarev, L. Guetaz, H.M. Meyer, C.M. Parish, and K.L. More, “Imaging and Microanalysis of Thin Ionomer Layers by STEM,” Journal of The Electrochemical Society
161[10] F1111-F1117 (2014).
Fuel Cell Electrodes Based on Functional Meso-Structured Arrays
Authors: Spendelow Jacob S , Komini Babu Siddharth , Mukundan Rangachary , Borup Rod L. , Cullen David A. , More Karren L. 
Published: February 2020

State-of-the-art fuel cell catalyst layers consist of a random mixture of functional components (catalyst, ionomer, and pore) that are formed in an uncontrolled ink deposition process. The random nature of these structures makes it difficult to optimize the functional domains and hence causes severe mass transport limitations during high-power operation, resulting in a loss in performance and requiring that the fuel cell be oversized to maintain an acceptable level of performance. The ionomer binder adds an additional transport resistance and becomes significant at lower Pt loadings [1]. Decreasing this transport resistance would remove the main barrier to low-cost, ultra-high power density fuel cells. Rational design of the electrode structure in PEFCs could improve performance and reduce cost. By separating the different electrode functions into discrete electrode elements, each element can be optimized for specific functions. Arranging these optimized discrete elements in a controlled, low-tortuosity array configuration enables transport limitations to be reduced or eliminated.
We have demonstrated this approach through fabrication of freestanding arrays of vertically-oriented ionomer channels with different aspect ratios, and incorporation of these channels into fuel cell electrodes where they serve as non-tortuous proton-transport highways (Figure 1). Providing effective proton transport through these low-tortuosity percolating highways allows the catalyst domain to have a lower ionomer/catalyst ratio, reducing transport resistance. Proof of concept was demonstrated by achieving a 15% increase in performance with channels with an aspect ratio of 8. Further work is underway to increase channel aspect ratio and improve integration of channels with surrounding catalyst layer, leading to further transport improvements and increases in performance.
Fig. 1. Left: freestanding array of ionomer channels. Right: catalyst layer incorporating ionomer channels.
References

N. Nonoyama, S. Okazaki, A. Z. Weber, Y. Ikogi, and T. Yoshida, J. Electrochem. Soc., 158, B416 (2011).

Acknowledgments
This research is supported by DOE Fuel Cell Technologies Office, through the Fuel Cell Performance and Durability (FC-PAD) Consortium.

Figure 1
Ionomer and Carbon Aggregate Structure in Catalyst Ink Using Coarse-Grained Molecular Dynamics Simulations
Authors: Mabuchi Takuya , Tokumasu Takashi 
Published: February 2020

The cathode catalyst layer (CL) is one of the principal components for proton exchange membrane fuel cells. CL is typically prepared by drying a catalyst ink consisting of Pt-C (platinum on a carbon power support), ionomer, and solvents (water/alcohol mixtures). Under good solvent conditions for the polymer backbone, where solvents dissolve the backbone chains, ionomers exhibit polyelectrolyte-type behavior, forming loose ionic aggregates. The interaction between ionomer and solvents controls the ionomer conformations in the solutions, which determines the final microstructure of ionomer in CLs. The characterization of ionomer structures has been extensively studied using experimental measurements such as small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS).1-2 They observed that hydrophobic backbones of Nafion form the cylindrical-like core of self-assembled ionomer structures while ionic groups are located at the periphery of this aggregates. Theoretically, while most of studies have primarily focused on the solid membrane state with water volume fraction significantly below 50%, ionomer and carbon aggregations in solutions are also an important phenomenon to understand the self-assembly behaviors of ionomers as key structure-forming elements in CL. In this study, ionomer and carbon aggregations in a mixture of 1-propanol (NPA) and water have been investigated using coarse-grained molecular dynamics simulations. To perform simulations of larger systems and longer time spans compared with atomistic simulations, the reduced spatial resolution of the bead representation based on the relative free energy difference was used as a coarse-grained model. The dependence of NPA content on the ionomer structures was studied by systematically changing the NPA content in the system. The self-assembly behavior of ionomers into cylindrical bundle-like aggregates was observed for all NPA content solutions (Figure 1). Ionomer aggregates showed different behavior of formation at different NPA contents. The radius of an ionomer bundle was found to become smaller as NPA content increases, which is in good agreement with the trend seen in experimental measurements.3 The effects of carbon particles on the ionomer aggregation for various ionomer concentrations will also be discussed in the presentation.
References

Gebel, G.; Loppinet, B.; Hara, H.; Hirasawa, E., Small-Angle Neutron Scattering Study of Polyethylene-Co-Methacrylate Ionomer Aqueous Solutions. J. Phys. Chem. B
1997, 101, 3980-3987.

Jiang, S.; Xia, K.-Q.; Xu, G., Effect of Additives on Self-Assembling Behavior of Nafion in Aqueous Media. Macromolecules
2001, 34, 7783-7788.

Yamaguchi, M.; Matsunaga, T.; Amemiya, K.; Ohira, A.; Hasegawa, N.; Shinohara, K.; Ando, M.; Yoshida, T., Dispersion of Rod-Like Particles of Nafion in Salt-Free Water/1-Propanol and Water/Ethanol Solutions. J. Phys. Chem. B
2014, 118, 14922-14928.

Figure 1