bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Next-Generation Zinc–Air Batteries: Progresses, Challenges, and Perspectives
Authors: Xu Nengneng , Qiao Jinli , Zhou Xiao-Dong
Published: February 2020

During the past few years, flexible batteries have gained increasing interest because of their applications in wearable electronics, smart packing, flexible displays and so on. Flexible zinc-air battery is a viable and promising device, attributed to their extremely high theoretical density (1084 W h kg-1), low cost, eco-friendly nature, flat discharge voltage, and high safety. There are, however, some major obstacles that must be circumvented in order to achieve a widespread commercialization of Zn-air batteries. One of the major challenges is that rechargeable zinc-air batteries are limited by the slow kinetics for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), on which the battery efficiency, charge-discharge rate, and cycling stability are dependent. As a result, it is of paramount importance to develop highly active and stable electrodes for zinc-air battery. In this talk, we will summarize our recent work on the development of cell materials for Zn-air batteries, including zinc electrodes, electrolytes, and air electrodes. Focus will be on the discussion of electrode/electrolyte interface and its role on the battery performance and performance stability. In addition, we will discuss our perspective on limitations and opportunities for the commercialization of this technology.
(Invited) Catalysts for Fuel Cells
Authors: Lopes Pietro Papa , Strmcnik Dusan , Wang Rongyue , Lv Haifeng , Becknell Nigel , Markovic Nenad M , Stamenkovic Vojislav
Published: February 2020

The progress in platinum-based catalysts with the goal of improving their activity and durability in a proton exchange membrane fuel cell will be presented. The studies of the oxygen reduction reaction on well-defined surfaces have guided the approach to design of the real world nanostructured catalysts. Insights from single crystalline systems and thin film surfaces have yielded atomically precise information related to surface structure and alloying with other metals in the quest to improve their intrinsic catalytic activity. These experimental efforts are also producing information necessary for the design of catalysts with enhancing stability. Atomic level control of the positioning of elements within catalyst structure enables the design of shapes and surfaces that mimic the key descriptors discovered through research on well-defined surfaces. The meticulous characterization of nanoscale materials using extremely high-purity conditions and cutting-edge techniques provides greater understanding of their performance and degradation pathways. This knowledge enables implementation of these materials in membrane electrode assemblies (MEA) for demonstration of targeted performance in a fuel cell vehicle.

The catalyst, its support, water, ionomer, and gaseous reactants create challenging environment to control and engineer at the level that would be capable to address all technical targets that are necessary for wide deployment of this technology. The transition from high-purity liquid electrolytes into MEA still needs to be addressed before stepping into mass production of fuel cell stacks. The overall research strategy presented here exhibits the merits of a continuous pipeline from fundamental to applied research in the development of fuel cell technology.
(Invited) Pathways Towards High-Performance Reversible Alkaline Membrane Fuel Cells
Authors: Xu Hui , Wu Gang , Yan Yushan
Published: February 2020

Reversible fuel cells have advantages over rechargeable batteries (Ni/MH or Li-ions) due to their high energy density, minimal self-discharge, and low cost. Reversible alkaline membrane fuel cells (AMFC) are attractive due to their ability to work with platinum-group-metal (PGM)-free catalysts. Major factors that limit the application of reversible AMFCs are low performance of bifunctional oxygen catalysts, alkaline membrane stability, and water management, which lead to high cost and low round-trip efficiency (RTE).

We have developed a variety of high-performance metal oxides/nanocarbon bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts, which have demonstrated remarkable reversibility and stability under harsh voltage cycling from 0.0 V to 1.9 V, providing a solid foundation for enabling reversible AMFCs. However, during membrane and electrode (MEA) development, it was found that the alkaline membrane and ionomer degraded rapidly at high electrolysis voltages. Thus, hydroxide ion transfer paths across the membrane and in the electrodes were largely blocked. Although the introduction of diluted carbonate salt (e.g., NaHCO3) or base (e.g., KOH) solutions can help to retain the electrolysis operation to some degree, it leads to flooding and complicates the reversible fuel cell system.

In this work, we will present some solutions to the challenges of reversible AMFCs, thus realizing high-efficiency reversible fuel cell operations. First, oxidation-resistant alkaline membranes and ionomers that are stable under oxidation conditions will be discussed, to eliminate the need of carbonate salt (e.g., NaHCO3) or base (e.g., KOH) solutions. Second, high-performance bifunctional catalysts for hydrogen evolution reaction (HER)/hydrogen oxidation reaction (HOR) and ORR/OER catalysts will be elaborated. Furthermore, advanced MEAs will be designed to minimize water transport-associated reversible fuel cell performance loss. These combined efforts can improve the RTE to 50% at an appreciable current density (>500 mA/cm2).

Acknowledgement: The project is financially supported by the Department of Energy’s Fuel Cell Technology Office under the Grant DE-EE0006960.
(Invited) Molecular Engineering of Quaternary Ammonium Aromatic Polymers for Anion Exchange Membrane Fuel Cells
Authors: Bae Chulsung
Published: February 2020

As a promising alternative to proton exchange membrane fuel cells (PEMFCs), anion exchange membrane fuel cells (AEMFCs) have received great attention in recent years. The high pH operating condition of AEMFCs allows use of non-precious metal catalysts and less expensive metal hardware. Recently, a power density over 1.0 W cm-2 has been achieved for AEMFC approaching close to that of PEMFCs. One of key requirements for high performance of AEMFCs is anion exchange membranes (AEMs) with high ion conductivity, good chemical stability and mechanical durability. New materials development using novel polymer backbones and side chain ionic functional groups have been extensively investigated over the past decade.

In this study, we will present the effects of different structures of polymer backbones and the location of ionic side chains on the membrane properties of AEMs and their fuel cell performance. Polymers made of soft backbone, such as polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS), and rigid backbones, such as polyarylenes containing biphenyl and terphenyl core groups (namely BPN and TPN series), have been evolved from my group at RPI over the past years. Because the backbone of those polymers are made of all carbon-carbon bonds, they showed excellent chemical stability under alkaline conditions. The high molecular weights (>100,000 g/mol) of those functionalized polymers also afforded good mechanical strength and high strain when made into film. A perspective of quaternary ammonium-functionalized polymers that have been developed from RPI will be presented with emphasis on synthetic strategy and materials performance in AEMFC test condition.
(Invited) High Performance Alkaline Membrane Fuel Cells Powered By Direct Ammonia
Authors: Achrai Ben , Tamir Gal , Kitayev Anna , Tal-Gutelmacher Ervin , Page Miles
Published: February 2020

Alkaline exchange membrane fuel cells (AEMFCs) have gained significant attention in recent years owing to several advantages over the industry-standard proton exchange membrane fuel cells (PEMFCs) such as lower cost materials (e.g., non-PGM electro-catalysts, hardware, etc.)

Less commonly cited are potential advantages of AEMFCs with respect to alternative fuels. Ammonia is a particularly attractive carbon-free fuel, being liquid at room temperature under ~7 atm, resulting in very high volumetric energy density and simplified distribution relative to hydrogen which is typically compressed to 200-700 atm. Furthermore, ammonia cannot be used as a fuel in PEMFCs since in the acidic environment ammonia exists primarily as ammonium which displaces the H+ ions that impart conductivity to the polyelectrolyte.

One of the key challenges in direct ammonia fuel cells is to execute the sluggish ammonia oxidation reaction (AOR) effectively. Previous successful attempts at operating direct ammonia fuel cells, therefore, all utilized high-temperature approaches such as solid oxide fuel cells (SOFCs) operated at ~600-850 °C [1] or alternatively, alkaline fuel cells (AFCs) operated at ~140 °C with concentrated KOH solutions as the electrolyte [2]. Additionally, a few attempts have been made to operate at lower temperatures with ammonia as a fuel, yielding very low power densities (<20 mW/cm2) [3-4].

In this study, we report for the first time, a direct NH3/O2 AEMFCs operated completely free of liquid electrolyte – in both the membrane-electrode assembly and the fuel feed. Utilizing operating temperatures of 100-120 °C to minimize losses from the AOR, and optimizing operation conditions and MEA design, yielded a peak power density of 270 mW/cm2 with no added electrolyte, and 450 mW/cm2 with the addition of dilute (1M) KOH to the fuel feed. Optimization was also carried out to stabilize performance over several hours with minimal voltage loss, thereby demonstrating sustained ammonia oxidation in the absence of any hydroxide additives. This work thus demonstrates the applicability of a high-performance direct ammonia-powered AEMFCs.

[1] Hagen A., "Use of alternative fuels in solid oxide fuel cells." Fuel 2.2H2 (2007): H2.

[2] Simons E.L., Cairns E.J., Surd D.J., "The performance of direct ammonia fuel cells." Journal of The Electrochemical Society 116.5 (1969): 556-561.

[3] Rong L., Tao S., "Direct ammonia alkaline anion-exchange membrane fuel cells." Electrochemical and Solid-State Letters 13.8 (2010): B83-B86.

[4] Kuntke P., Sleutels T.H.J.A., Saakes M., Buisma C.J.N., "Direct ammonia fuel cell performance using PtIr/C as anode electrocatalysts." international journal of hydrogen energy 39.10 (2014): 5148-5152.
The Effect of Length of Spacer on the Anodic Oxidation of Bisamides
Authors: Becker James Y. , Golub Tatiana
Published: February 2020

Previously we studied the anodic oxidation of different types of amides, including cyclic ones [1-3]. Recently we investigated [4] the anodic oxidation of bisamides (from diaminoalkanes) involving 2-4 methylene groups as spacers between the two amide functionalities. Those with 3 and 4 methylene groups behave similar to monoamides. They both undergo mostly mono- and dimethoxylations at the alpha-position to 'N' atom. However, when the spacer contains two methylene groups only, the anodic process affords mostly fragmentation products due to CH2-CH2 bond cleavage: RCONHCH2OCH3 exclusively, or along with RCONHCHO, depending on the supporting electrolyte used. The scheme below describes the outcome in both cases:

References

[1] Golub T.; Becker J. Y., Org. Biomol. Chem. 2012, 10, 3906-3912.

[2] Golub T.; Becker J. Y., J
. Electrochem. Soc. 2013, 160, G3123-G3127.

[3] Golub T.; Becker J. Y., Electrochim. Acta
2015, 173, 408–415.

[4] Golub T.; Becker J. Y., Beilstein J. Org. Chem.
2018,
14, 861–868.

Figure 1
Effect of Plasmon Stimulation on the Extraction of Photosynthetic Electrons from Thylakoid Membranes
Authors: Kim Yong Jae , Hong Hyeonaug , Yun JaeHyoung , Kim Seon Il , Ryu WonHyoung
Published: February 2020

Because of extremely high internal quantum efficiency of photosynthesis, photosynthetic bio-solar energy conversion has drawn much attention recently in the field of renewable energy. Thylakoid membranes (TMs) are the place where photosynthesis occurs. Since TMs can be easily isolated from plants or algae and remain stable after isolation, they are widely used in photosynthetic energy transfer systems. However, despite its high conversion efficiency from photons to photosynthetic electron (PE), their overall efficiency is limited due to limited absorption of incident photons and low extraction efficiency of PEs. Therefore, several approaches were developed to increase PE extraction by improving electrical connections between TMs and electrodes such as amine or carboxyl modified carbon nanotube electrode, titanium oxide (TiO2) modified electrode or reduced graphene oxide (rGO) modified electrode. Furthermore, PE extraction can also be increased by stimulating photosynthesis to produce more PEs. Recently, it was demonstrated that photosynthesis stimulation could be achieved by inducing localized plasmon field very close to the light energy harvesting complexes within isolated photosystem I or II.

In this study, we aimed to enhance PE extraction by stimulating photosynthesis using plasmon induced resonance energy transfer (PIRET). Gold nanorod (AuNR) was used to induce plasmonic field close to the TMs for photosynthesis stimulation and the geometry of AuNR was carefully selected to match its plasmon resonance wavelength with the absorption wavelengths of photosystem I or II within TMs. Therefore, AuNRs of 17 nm width and 45 nm length were chosen to have their plasmon resonance peak at 675 nm. On the other hand, since plasmonic energy can be transferred only in a few nanometer ranges, AuNR should be located very close to TM. Therefore, a tethering molecule which can link AuNR and TM was added to attach the AuNRs to TMs. The tethering molecule has poly ethylene glycol (PEG) chain and two functional groups of thiol group (-SH) and succinimide ester (NHS ester) group at each terminal end. To make AuNR-PEG-TM conjugation, the tethering molecule solution was added to an AuNR in distilled water (DIW) suspension to form AuNR-PEG-NHS. Then, a TM solution with phosphate buffer saline (PBS) was added to the mixture so that AuNR-PEG-TM conjugation was finally formed. Each intermediate product was characterized using SEM, TEM, optical, fluorescence spectroscopy, and XPS analysis. The PE currents from AuNR-PEG-TM was measured and compared to PE currents from pure TM. With the AuNR-PEG-TM conjugation, the PE current was increased by 400% compared to the PE currents of pure TM.
Side-Selective Modification of Photosystem I Protein and Preparation of Oriented Photo-Electrochemical Films
Authors: Wolfe Kody
Published: February 2020

The directional orientation of photoreactive protein complexes extracted from plants, algae, and cyanobacteria is of crucial importance to the performance of biologically-modified, photo-active electrodes. The photo-electrochemical response of such protein complexes is inherently directional and achieving uniform orientation is necessary to mitigate problems such as electron-hole recombination, low net charge transfer due to competing electrochemical reactions, and loss of direct electron transfer to the electrode. [1] Previous efforts to control orientation have explored bio-conjugation [2] and electrostatic interactions with self-assembled monolayers (SAMs) [3] to improve photocurrent generation. However, the ability to efficiently modify, deposit, and characterize the orientation of such bio-electrode films has not been demonstrated.

To achieve controlled orientation, an extraction-modification procedure has been developed based on side-selective functionalization of photosystem I (PSI), a photo-active protein complex derived from spinach. Reactive amine groups on the surface of PSI can be leveraged to incorporate a variety of new functional groups through solution-based modification reactions. The functional group chosen for modification can be tailored to achieve oriented deposition on the substrate electrode. Herein we explore modification strategies utilizing the thiol-gold affinity and polyethylene glycol (PEG) “capping”. The deposition kinetics, monolayer structure, and electrochemical reactivity of the modified PSI monolayers have been studied to better understand the ability to control PSI orientation on gold electrodes. Controlled orientation will allow for the future development of oriented PSI based devices such as biohybrid photovoltaics or electrochemical photocatalysis membranes, and this facile modification procedure may be implemented with other membrane bound proteins and protein complexes.

[1] G. LeBlanc, et al, Langmuir, 30 (37), 10990–11001, 2014.

[2] R. F. Simmerman, et al, Bioconjugate Chem, 26 (10), 2097–2105, 2015.

[3] K. A. Manocchi, et al, Langmuir, 29 (7), 2412–2419, 2013.
Understanding Amyloid-Beta Plaque Formation By Monitoring the Redox Activity of Copper at the Active Site
Authors: Tabaka Amber Lynn , Sanchez Erik , Nashed Dina , Havens Mallory A. , Keleher Jason J. , Kissel Daniel S.
Published: February 2020

The Amyloid β peptide (Aβ-42) can be expressed through cleavage of a precursor protein (APP) during post-translational modification as a result of oxidative stress in the brain. Once expressed, the peptide will readily form binding interactions with free metal ions, particularly Cu2+, initiating a series of redox reactions that result in the production of Reactive Oxygen Species (ROS) and amyloid plaques within the brain. This process has been implicated as the major contributing factor in neurodegeneration in Alzheimer’s patients. An increasingly promising area of study in the treatment of AD is to disrupt this pathway using metal ion chelation, which can serve as a form of therapeutic treatment. The work presented herein focuses on different copper coordination compounds and their redox activity using various ligands such as glycine, beta alanine, phenylalanine, 2,2’-bipyridine (bipy), 2,2’-thiodipyridine (DPS), 2,2’-dipyridylamine (DPA), and 1,10-phenanthroline-2-thiopyridine (TPP). Utilizing Cyclic Voltammetry to monitor redox activity, the more stable ligand complexes resulted in a more quasi-reversible cyclic voltammogram, allowing for potential redox cycling between Cu2+ and Cu+ at the Aβ-42 active site. The CV results correlated well with hydroxyl radical trapping experiments that measured the rate of hydroxyl radical production in each complex, and a relationship between redox activity and hydroxyl radical production was observed. With the Aβ-42 peptide, these coordination complexes were analyzed using Atomic Force Microscopy (AFM) to correlate the rate of fibril formation to plaque formation. These results provide valuable insight into ligand design characteristics important for the development of potential therapeutic treatments that slow AD progression.
Visible Light-Driven Cross Coupling Reactions Catalyzed By B12 Complex with Photosensitizer
Authors: Shimakoshi Hisashi , Chen Li , Hisaeda Yoshio , Anai Yuki
Published: February 2020

Organometallic B12 compounds are unique metal complexes having a cobalt-carbon σ-bond present in biological systems [1]. Cleavage of the metal-organic σ-bond initiates many B12-dependent enzymatic reactions. The alkylated cobalt complex is generally formed by the reaction of the Co(I) state of the complex with electrophiles such as an organic halide in vivo. Therefore, the reductive formation of the Co(I) species followed by formal oxidative addition of the organic halide to form the alkylated cobalt complex are key steps for the development of the B12 catalyzed enzymatic reactions. Our group has been reported the photosensitizing formation of the Co(I) species of the B12 derivative, heptamethyl cobyrinate perchlorate, using various photosensitizers (PSs) such as, [Ru(bpy)3]Cl2 or cyclometalated iridium(III) complexes and performed various B12 model reactions such as 1,2-migration of functional groups, dechlorination and so on [2,3]. Here, a visible light driven Heck-type coupling reaction of alkyl halides with styrene and its derivatives catalyzed by the cobalamin derivative (B12) with the [Ru(bpy)3]Cl2 photosensitizer at room temperature is reported. The catalytic efficiencies of the B12 catalyst were compared to that of other cobalt complexes such as cobaloxime. Various control experiments supported a radical-based mechanism similar to those for typical B12 model reactions. An unique coupling reaction combined with 1,2-migration of the functional group is also reported. Mild reaction conditions using an environmentally benign cobalt catalyst derived from the natural B12 provided a practical protocol for the synthetic organic chemistry of the B12 catalyzed reaction system.

[1] Reviews: a) H. Shimakoshi, Y. Hisaeda, Current Opinion in Electrochem. 2018, 8, 24; b) H. Shimakoshi, Y. Hisaeda, ChemPlusChem. 2017, 82, 17 (Back cover).

[2] H. Tian, H. Shimakoshi, T. Ono, Y. Hisaeda, ChemPlusChem
2019, in press (Front cover).

[3] H. Shimakoshi, Y. You, Y. Hisaeda et al, Dalton Trans. 2018, 47, 675 (Front cover).
Ethanol Production from Saccharum Spontanum Biomass Native to Nepal Using Bioelectrochemical Cell
Authors: Joshi Jarina
Published: February 2020

Bioethanol can be used as an octane enhancer and alternative replacement to blend with petroleum fuels. Using an electrochemical cell for the production of bioethanol facilitates the enhancement in ethanol production exploiting the electrochemical redox reactions occuring inside the cell. The externally supplied voltage is used to drive the chemical reactions to generate the metabolite, i.e; ethanol. A microbial electrochemical cell was designed with porous carbon fiber coated with neutral red as cathode and platinum wire coated with fine platinum as anode. Saccharum spontanum biomass pretreated with hot water at 100oC for 2 hours followed by acid hydrolysis was neutralized and used for production of ethanol by Saccharomyces cereviseae in electrochemical cell. A total supply of 4V was found to be best for maximum ethanol production in 300 ml fermentation volume.

Key words: ethanol, microbial electrochemical cell, voltage.
Electrochemically Stable and Adherent PEDOT Coatings for High Quality EMG Recording
Authors: Rossetti Nicolò , Luthra Prabhjot , Lee Ada , Bodart Leguen Come , Cicoira Fabio
Published: February 2020

Conductive polymers coatings on metal electrodes are an efficient solution to improve neural signal recording and stimulation due to their mixed electronic-ionic conduction and biocompatibility [1]. However, only a few studies have been reported on conductive polymers coatings on metallic wire electrodes for muscle signal recording [2,3]. In this work, we developed mechanically and electrochemically stable invasive electrodes for muscle signal recording in small animals based on stainless steel multi-stranded wires coated with the conductive polymer PEDOT.

PEDOT doped with LiClO4 was galvanostatically electropolymerized on stainless steel wires using three different solvents: propylene carbonate (organic), acetonitrile (organic) and water (inorganic). The coatings adhesion to the metallic substrate was tested through ultrasonication and the electrochemical stability was evaluated through phosphate buffer solution soaking test and autoclave sterilization.

The solvent played a key role on the adhesion of the PEDOT coating, with organic solvents giving the best mechanical stability. Electrodes prepared with these solvents possessed excellent electrochemical stability and survived sterilization and prolonged soaking without major changes in electrochemical properties.

A solution for high quality invasive muscle signal recording in small animals based on conductive polymers has been demonstrated.

References

[1] R. Balint, N. J. Cassidy, and S. H. Cartmell, "Conductive polymers: Towards a smart biomaterial for tissue engineering," Acta Biomaterialia, vol. 10, no. 6, pp. 2341-2353, 2014.

[2] S. Kim, L. K. Jang, M. Jang, S. Lee, J. G. Hardy, and J. Y. Lee, "Electrically Conductive Polydopamine–Polypyrrole as High Performance Biomaterials for Cell Stimulation in Vitro and Electrical Signal Recording in Vivo," ACS Applied Materials & Interfaces, vol. 10, no. 39, pp. 33032-33042, 2018.

[3] H.-C. Tian et al., "Enhanced Flexible Tubular Microelectrode with Conducting Polymer for Multi-Functional Implantable Tissue-Machine Interface," Scientific Reports, Article vol. 6, p. 26910, 2016.
High-Yield Urea Electrochemistry Synthesis Derived from Direct CO2 Activation in Ionic Liquid
Authors: Ling Pinghua , Huang Zhongyuan , Winchester Williams , Riley Kevin , Wang Zhe
Published: February 2020

In this work, we present a facile electrochemical approach to synthesize urea from amines and CO2 directly using ionic liquid (IL) as the catalyst. This procedure works could give urea without the addition of any additives or tedious work-up. The results indicated that cyclohexylamine, cyclopentylamine, pentylamine and octylamine was converted to high yield of corresponding urea through a very low-potential (~1.0 V) CO2 activation in ionic liquid. The yield and selectivity of urea production exhibited a strong dependence on the structure of amine and ionic liquid. This process was considered as an E-C process that initiated from our recent discovered CO2 activation. This new chemistry described here may be particularly used for understanding the chemical properties of ionic liquid and particularly provide a promising lead for the development of practical catalysis for the low-cost urea synthesis.
Monolayer Effects on Surface Plasmon Resonance of Au Thin Films
Authors: Artur Camille , Yarali Miad , Ahmadi Kamyar , Shan Xiaonan , Brankovic Stanko
Published: February 2020

Surface plasmons (SP’s) or surface plasmon polaritons are longitudinal electromagnetic waves which propagate at the interface between a metal and a dielectric. They are localized in the interface and are sensitive to the optical properties of the materials comprising the interfacial region. As such, the SP present a unique probe to study the electrochemical interface and double layer [[1],[2]].Typical plasmonic metals/electrodes are Au and Ag thin films, which have been a subject of studies where the SPs have been used to probe the electrochemical processes such as adsorption and underpotential deposition [1,[3],[4]]. The most recent developments indicate that the SPs can be used to enhance certain electro-catalytic and photocatalytic reactions [[5]].

In this report, we present the results investigating the catalyst monolayer modification effect on plasmon resonance of Au thin films. The experiments are conducted using an attenuated total reflection arrangement in which p-polarized light is incident through a prism onto a thin (-400 A) Au film deposited on the mica substrate. (Kretschmann configuration [[6]]). The angle of incidence on the base of the prism is greater than the critical angle for the prism: electrolyte interface and SPs are excited by the evanescent wave generated under these conditions of total internal reflection. The excitation is manifested by a decrease in the intensity of reflected light. The Pd monolayer on Au were electrodeposited using procedure reported by Kolbe et al [[7],[8]], while the Pt submonolayer/monolayers were deposited on Au using Surface Limited Redox Replacement (SLRR) of Pb UPD monolayer [[9]]. The plasmon resonance frequency of Au(hkl), PdML/Au(hkl) and PtML/Au(hkl) and PtSML/Au(hkl) were investigated as a function of the applied potential in the range between -0.24 V to 0.4 V vs. SCE. The comparative analysis, between Au and catalyst monolayer modified Au(hkl) samples indicate that SP resonant frequency change is induced by both; surface charge and adsorption of H on the catalyst monolayer surface in the UPD region. The latter effect is quantified using subtractive analysis between the Au and catalyst modified Au surface and solutions with different pH. In conclusion, we present a simple model describing the catalyst monolayer effect on plasmon resonance of Au films.

[1] J.G. Gordon II and S. Ernst, Surface Science, 101 (1980) 499

[2] R. Kotz et al, Surface Science, 69 (1977) 359

[3] D.M. Kolb, D. Leutloff and M. Prasnyski, Surface Science, 47 (1975) 622

[4] A. Bewick, and B. Thomas, J. Electroanalytical Chem., 65 (1975) 911

[5] S. Linic, U. Aslam, C. Boerigter and M. Morabito, Nature Materials, 14, (2015) 567.

[6] E. Kretschmann and H. Raether, Z. Natutforsch. 23a (1968) 2135.

[7] L.A. Kibler, M. Kleinert, R. Randler, D.M. Kolb, Surface Science, 443 (1999) 19.

[8] J. Tang, M. Petri, L.A. Kibler, D.M. Kolb, Electrochimica Acta, 51, (2005) 125

[9] K. Sasaki et al, Electrochim. Acta, 55, (2010) 2645.
Strain Effect on Electrolytic Hydrogen Isotope Separation
Authors: Hasanzadehshirazi Mehrnaz , Dongjun Wu , Artur Camille , Grabow Lars , Brankovic Stanko
Published: February 2020

The effect of strain in Pt and Pd monolayer catalyst is explored for electrolytic hydrogen isotope separation. Positive/negative strain increases/decreases strength of adsorbed hydrogen bond in overpotential region where recombination of hydrogen atoms is the rate determining step in hydrogen evolution reaction. As a result, the increased/decreased hydrogen isotope separation efficiency of Pt and Pd monolayers is expected as compared to bulk Pt and Pd. The positive/negative strain rises/lowers diffusion barrier for adsorbed hydrogen atoms. This effect favors/retards recombination of isotopes with smaller mass. As the surface is stretched/compressed, the neighboring adsorption sites separate/approach each other which affects heavier hydrogen isotopes more/less and results in their lower/higher probability for recombination. All these fundamental consideration indicate that Pt and Pd monolayers with different level of strain should have much different separation factors than corresponding bulk electrodes. To study described effects, Pt and Pd monolayers we synthesized electrochemically on Au(111) and Ru(0001) electrodes each yielding qualitatively different strain levels (Au-positive, Ru-negative). Pd monolayers are synthesized using electrodeposition[1] while Pt monolayers were synthesized using deposition via surface limited redox replacement reaction[2]. The adsorption strength of hydrogen isotopes is studied by infra-red spectroscopy. These results will are input in our classical models for isotope separation[3] and to our DFT calculations. The calculated ratio between the rates of hydrogen and deuterium recombination and separation factors for Pt and Pd monolayers and corresponding bulk electrodes are compared to experimentally measured ones. The following discussion is focused on understanding and quantification of strain effects on separation efficiency of Pt and Pd monolayers.

[1] H. –F. Waibel, M. Kleinert, L. A. Kibler, and D. M. Kolb, Electrochim. Acta, 47, 1461 (2002).

[2] S. R. Brankovic, J. X. Wang and R.R. Adzic, Surface Science, 474, L173 (2001).

[3] B. E. Conway, Proceedings of The Royal Society of London, A. Mathematical and Physical Sciences, 247, 400 (1958).
Electrodissolution Inhibition of Gold Nanorods with Oxoanions
Authors: Flatebo Charlotte , Collins Sean Stevenson Edward , Hoener Benjamin S , Cai Yiyu , Link Stephan , Landes Christy F
Published: February 2020

The incorporation of metal nanoparticles into bulk electrochemical systems has resulted in technological advances in electronics, electrocatalysis, and sensing. Metal “nanoelectrodes” are exposed to varied chemical environments that can cause dissolution under applied potentials, often below bulk oxidation values. Gold nanorods are being developed as superior light harvesting nanoantennas in photoelectrocatalysis, and light scatterers for nanoscopic spectroelectrochemical sensing. However, dissolution poses a critical problem for gold nanoelectrode functionalized devices as the electrochemical and optical properties of nanoparticles are highly dependent on size and shape, and the cost of replacement can be prohibitive. We employed an analytical, single particle approach to monitor the chloride-mediated dissolution pathway of gold nanorods in the presence of oxoanion electrodissolution inhibitors. Hyperspectral dark-field imaging revealed that the morphological stability of gold nanorods at anodic potentials improved with the addition of low relative concentrations of oxoanions to aqueous halide electrolyte solutions. Single particle measurements were necessary to address the inter-particle heterogeneity of chemically synthesized gold nanorods. Direct correlation imaging of single gold nanorods with scanning electron microscopy supported the reaction pathway heterogeneity statistics and electrodissolution potentials obtained spectroscopically. We determined that the electrodissolution inhibition capacity of oxoanions in the presence of chloride ions for gold nanoparticles was governed primarily by the electroadsorption potential and ionicity of the oxoanion. Determining the factors for inhibition will assist in the expansion of the electrochemical stability window, opening new avenues for gold nanoelectrodes in diverse and harsh catalytic and sensing environments.
An Ultra-Long Cycle Life Sn Anode with High-Rate Performance for Sodium Ion Batteries
Authors: Kim Changhyeon , Kim Icpyo , Kim Hui-Hun , Sadan Milan K , Yeo Hyewon , Cho Gyu-bong , Ahn Jae-Pyoung , Ahn Jou-Hyeon , Ahn Hyo-Jun
Published: February 2020

The development of large-scale batteries for green energy system are important. Sodium-ion batteries have attracted significant interest because of the abundance of sodium resources. The sodium cathode materials already were developed with comparable performance with lithium ion batteries. However, sodium anode materials showed poor performance compare with lithium ion equivalent so far. So, development of an anode with high performance is needed for commercialization of sodium batteries. Sn is one of the promising candidate for the anode for sodium ion batteries. We study a Sn anode with commercial micron-sized Sn particles and the anode is analysed by SEM, TEM, in-situ SEM. We found the self-healing phenomenon from cracking and pulverization of the anode during cycling. During electrochemical cycling, the structure of Sn particles was dynamically changing to a stable porous structure. Finally, The stable porous structure of Sn anode showed improved electrochemical performances. Furthermore, its capacity retention and coulombic efficiency are near to 100% during cycling. The structure by reassembling phenomenon can act as a new strategy for high performance electrode with alloying materials.
A Square Channel Vanadium Phosphite Framework As Cathode for Li- and Na- Ion Batteries
Authors: Sandineni Prashanth , Madria Pranal , Choudhury Amitava
Published: February 2020

The need for high-performance cathode materials for lithium and sodium-ion batteries has been the main driving force to explore new materials through innovative solid state chemistry. Polyanion-based cathode materials are shown to be promising cathode materials for both Na- and Li-ion batteries. Recently, we have expanded the family of polyanion-based cathodes by introducing phosphite-based (HPO3
2–) materials as viable cathode for Li-ion batteries, for example, LiFe(HPO3)2 and Li3Fe2(HPO3)2Cl.1, 2 In an effort to double the capacity we intended to replace Fe with V in these structures as V is known to display facile V+2/V+3 and V3+/V4+ couples. In this presentation, we will discuss the synthesis of LiV(HPO3)2, iso-structural to the reported iron compound, LiFe(HPO3)2 and their electrochemical properties with respect to lithium and sodium-ion batteries. The synthesized V compound display facile electrochemical properties with an average voltage of 4.0 V vs Li+/Li and 3.8 V vs Na+/Na in Li- and Na–ion batteries, respectively, when cycled between 4.5 to 1.5 V. The galvanostatic charge-discharge profile indicates that LiV(HPO3)2 can be cycled between V(HPO3)2 and Li2V(HPO3)2. Besides synthesis and electrochemistry, the presentation would also include spectroscopic and magnetic characterizations, details of structural characterization as a function of oxidation and reduction and some insights into the mechanism of alkali-metal insertion chemistry.

References:

Yaghoobnejad Asl, H.; Choudhury, A. Phosphite as Polyanion-Based Cathode for Li-Ion Battery: Synthesis, Structure, and Electrochemistry of LiFe(HPO3)2, Chem.

2015, 54, 6566 – 6572.

Yaghoobnejad Asl, H.; Ghosh, K., Vidal Meza, M. P.; Choudhury, A. Li3Fe2(HPO3)2Cl: An electroactive iron phosphite as a new polyanionic cathode material for Li-ion battery, Mater. Chem. A, 2015, 3 (14), 7488 – 7497.
The Stability and the Electrochemical Properties of Na3V3+
2-Y
V4+

y
(PO4)2F3-Y
O
y
(0 ≤ y ≤ 2)
Authors: Nguyen Hoang Bao Long , Broux Thibault , Sanz Camacho Paula , Fauth François , Carlier Dany , Olchowka Jacob , Masquelier Christian , Croguennec Laurence
Published: February 2020

Polyanionic materials are currently intensively studied as promising active materials for positive electrodes in Na-ion batteries thanks to their high stability and the fast ionic mobility within their structural framework. [1] Among those polyanionic materials, Na3V2(PO4)2F3 and Na3V2(PO4)2FO2 are the two most attractive ones due to their high voltage for two Na+ ions extraction and their high theoretical energy densities: 500 mAh.g-1 and 495 mAh.g-1, respectively. These two compositions are indeed the two end members of a family of compounds described with the general formula Na3V2(PO4)2F3-y
O
y
where 0 ≤ y ≤ 2. [2-6] We will discuss here in depth the chemical reaction used to prepare these materials, in order to understand the nature of the impurities and active compounds formed in some specific conditions, as well as the stability of these active compounds in aqueous media.

The combination of a large panel of characterization techniques reveals that the members of the Na3V2(PO4)2F3-y
O
y
family are stable in aqueous media, with no water intercalation in the channels of the structure and no Na+/H+ or F-/OH- exchange, despite of the long immersion time. These materials can thus be used for electrode formulation in aqueous media. [7] The electrochemical behavior and performance of Na3V3+
2(PO4)2F3, Na3V3+V4+(PO4)2F2O and Na3V4+
2(PO4)2FO2 will be compared for different cycling potential windows, with careful attention to their chemical stability.

References:

[1] C. Masquelier and L. Croguennec, Chem. Rev., 2013, 113, 6552–6591.

[2] R.K.B. Gover et al., Solid State Ionics 177 (2006) 1495–1500.

[3] J. Baker et al., J. Electrochem. Soc. 2004, 151 (10), 1670-1677.

[4] Y.-U. Park et al., Adv. Funct. Mater. 2014, 24 (29), 4603-4614.

[5] P. Serras et al., Chem. Mater. 2013, 25, 4917−4925.

[6] T.Broux et al., Chem. Mater. 2016, 28 (21), 7683-7692.

[7] P.R. Kumar et al., J. Mater. Chem. A, 2015, 3, 6271-6275.
Taming Cathode-Solid Electrolyte Interfaces with Organic Cathode Materials for All-Solid-State Batteries
Authors: Hao Fang , Chi Xiaowei , Liang Yanliang , Yao Yan
Published: February 2020

Attaining stable cathode-solid electrolyte interfaces is a great challenge in sulfide-based all-solid-state sodium batteries (ASSSBs). Currently, these ASSSBs experience low specific energy and poor cycling performance due to the interfacial incompatibility between cathode materials and sulfide electrolytes. A resistive layer forms at the interface when cathode is charged above the anodic stability potential of sulfide electrolyte, e.g. Na3PS4. In addition, most previous cathodes have been too rigid to accommodate cycling-induced volume change, resulting in poor interparticle contact. Herein, we demonstrate the capability of an organic cathode material, pyrene-4,5,9,10-tetraone (PTO), to enable a high-energy, high-power, and long-cycle-life ASSSB. We report for the first time a reversible cathode-electrolyte interfacial resistance evolution during the cycling of an all-solid-state battery, as the consequence of reversible conversion between conductive Na3PS4 phase and resistive Na4P2S8 phase, which occurs within the operation potential range of PTO. We further show PTO is capable of overcoming mechanical failures and maintaining intimate interparticle contact during cycling partially due to its low Young’s modulus (4.2 ± 0.2 GPa). The PTO-based ASSSB exhibits a high specific energy (587 Wh kg-
1) at the active-material level and an 89% capacity retention over 500 cycles, a record cycling stability among all ASSSBs reported to date. This work reveals an effective cathode design strategy toward compatibility with solid electrolytes and thus high-performance ASSSBs.
Identifying the Performance Limitations of Layered Oxide Sodium-Ion Batteries Using EIS
Authors: Middlemiss Laurence Adam , Rennie Anthony J R , Sayers Ruth , West Anthony R
Published: February 2020

Sodium-ion (Na-ion) batteries have received considerable attention in recent years as a cheaper, safer, more sustainable alternative to conventional lithium-ion (Li-ion) technology [1,2]. Battery cycle life is an important performance criterion with respect to the commercialisation of these. All batteries will experience, with time, some reduction in performance due to a variety of degradation mechanisms, some of which are linked to a rise in cell impedance [3]. Therefore, by carrying out a combination of constant-current, constant-voltage (CC/CV) cycling in combination with electrochemical impedance spectroscopy (EIS), it should be possible to identify the rate-limiting steps and problem interfaces inside a cell. Identifying such factors will make it possible to address them and therefore enhance overall battery performance.

We have applied electrochemical impedance spectroscopy (EIS) to layered oxide Na-ion cells in order to identify factors that limit cell performance. Figure 1 depicts the voltage profile for a typical cycle. These data were collected at charge and discharge rates of ~ C/10 and ~ C/5 respectively, using voltage limits of 4.2 V and 1.0 V. Figure 2 denotes a typical cycle life plot. A reversible capacity of 123 mAh/g (cathode) was retained after 100 cycles, indicating a charge retention of 98 %. Most of the capacity loss was recovered when subsequently cycled at lower rates, suggesting that this reduced capacity was due to increased cell impedance rather than an irreversible loss of Na.

EIS was performed on a range of different cell configurations, including a novel three-electrode pouch cell design. Spectra were recorded at varying states of health (SoH) and states of charge (SoC). Results were analysed by fitting ideal equivalent electrical circuits to impedance data, and using these to attribute resistances and capacitances for the different components present in the impedance response. Spectra were plotted using different complex formalisms in order to highlight different aspects of collected data, to the best of our knowledge this is an approach not previously reported in the analysis of batteries.

The cathode was found to be primarily responsible for resistive losses inside these layered oxide Na-ion cells, with the impedance associated with the positive electrode continuing to grow during cycling. Further characterisation and techniques to try and improve the performance of these sodium-ion batteries will be provided during the presentation.

References:

[1] J.W. Choi, and D. Aurbach, Nat. Rev. Mater., 2016, 1, 16013.

[2] N. Yabuuchi, K. Kubota, M. Dahbi, and S. Komaba, Chem. Rev., 2014, 114, 11636.

[3] J. Vetter, P. Novák, M. R. Wagner, C. Veit, K.-C.Möller, J. O. Besenhard, M. Winter, M. Wohlfahrt-Mehrens, C. Vogler, and A. Hammouche, J. Power Sources, 2005, 147, 269.

Figure 1
Anionic Redox in Li-Rich Rocksalt Oxides Studied Via X-Ray Photoelectron Spectroscopy
Authors: Coca Clemente Jose Antonio , Hardwick Laurence J. , Dhanak Vinod R.
Published: February 2020

Layered LiMO2 compounds can be considered as a progressive substitution of excess Li+ for M3+ in the [MO2] layers, with a 1:1 Li:M ratio. A derivative from this type of compound corresponds to a material with the general formula of Li(Li1/3M2/3)O2. This has been alternatively described with the formula Li2MO3 (where M has been reported as Mn, Ru, Ti, Zr, Sn, Pt), and often referred to as a “Li-rich” rocksalt oxide (with Li/M > 1 and space group C2/m). Li-rich rocksalt oxides are of technological importance as cathode materials in rechargeable Li-ion batteries. Recently, the possibility of using oxygen as a redox centre in this kind of oxides has been established in the design of cathode materials with enhanced capacities (> 200 mAh/g). [1-3]

Among the numerous compounds with Li-rich Li2MO3 structure type, Li2MnO3 is the most studied so far; the combination with other transition metals such as Co and Ni can help to improve the capacity, rate capability and reduce the capacity fading.

In this work, a study of a series of Li-rich compounds with rock salt structure was synthesised with a general formula of Li1+δ(Ni1-x-yCoxMny)1-δO2 and electrochemically cycled versus lithium metal. An increase in the specific capacity compared with materials of the same family such as layered LiNi1/3Co1/3Mn1/3O2 was observed, in line with numerous reports by research groups worldwide. In this presentation, X-ray photoemission spectroscopy of O1s taken at different stages of the load curve of the Li1+δ(Ni1-x-yCoxMny)1-δO2 electrode material will be presented. The experimental evidence pertaining to the oxidation of O2- driving to the formation of peroxo-like species (O2)n− in the material and charge compensating the extraction of Li+ ions by the removal of electrons from lattice oxygen; that allows this material to have more capacity than expected will be critically discussed.

References:

[1] Saubanère, M., McCalla, E., Tarascon, J.-M. & Doublet, M.-L. The intriguing question of anionic redox in high-energy density cathodes for Li-ion batteries. Energy Environ. Sci.
9, 984–991 (2016).

[2] Seo, D.-H. et al. The structural and chemical origin of the oxygen redox activity in layered and cation-disordered Li-excess cathode materials. Nat. Chem.
8, 692–697 (2016).

[3] Perez, A. J. et al. Approaching the limits of cationic and anionic electrochemical activity with the Li-rich layered rocksalt Li3IrO4. Nat. Energy
2, 954 (2017).
Understanding the Reaction Uniformity during Discharge of Thick Electrodes
Authors: Wang Fan , Tang Ming
Published: February 2020

The use of thick electrodes in Li-ion batteries can enhance cell-level energy density and lower the cost by reducing the fraction of inactive components. However, as the electrode thickness increases, reaction inhomogeneity along the thickness direction becomes a critical issue, which leads to not only inferior rate performance but also localized heat generation, overcharge or overdischarge, causing degradation and even failure of batteries. In this work, we analyze the discharge kinetics of thick electrodes in the framework of the porous electrode theory. Two characteristic reaction behaviors are identified, i.e. the uniform reaction behavior, which is exhibited in solid-solution-type electrode materials such as transition metal layered oxides, and the moving-zone reaction behavior, which applies to battery compounds that undergo first-order phase transformation(s) upon cycling such as LiFePO4 and Li4Ti5O12. A general analytical model is developed to describe the two types of reaction behaviors with good agreement with numerical simulations. We further elucidate the effect of various factors on controlling the reaction uniformity including current density, equilibrium potential, ionic and electronic conductivities and surface reaction kinetics through a simplified circuit model. Based on the understanding obtained from this model, we propose that intentionally reducing the electronic conductivity and surface reaction rate provide two counter-intuitive strategies to homogenize the non-uniform reaction distribution and improve the discharge performance of thick electrodes.