bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computer Simulations of Proton Discharge from Aqueous Solutions on Metal Electrodes
Authors: Spohr Eckhard 
Published: February 2020

A reactive trajectory approach for the study of proton discharge from aqueous environments on charged metal surfaces is reviewed. It is based on an extension of a minimalistic empirical valence bond (EVB) model to study proton transfer in the bulk. Extensive quantum mechanical density functional theory calculations were parametrized for the EVB force field [1]. The model is used to investigate reactive (discharging) proton trajectories which were started in the bulk of a water film adsorbed on charged metal electrodes. The results indicate a transition between a reaction-dominated regime at moderate negative charges, where the rate constant increases exponentially, to a “transport limited'' regime where the transfer rate is almost independent of the surface charge density (at highly negative surface charge densities) [2,3].
Extensions of the model to electrolyte solutions are discussed along corresponding results of trajectory calculations that introduce background electrolytes with and without specific ion adsorption are presented. In NaCl solutions, e.g., it is found that the discharge rate is slowed down relative to that in pure water. We discuss how this phenomenon is associated with adsorption site-blocking by ions from the electrolyte, and with the reduced number of water pathways for Grotthuss style proton hops as a consequence of the presence of hydration shells containing water molecules in unfavourable arrangements for proton transfer. Further mechanistic insight can be gained from temperature dependent studies [4].
[1] F. Wilhelm, W. Schmickler, R. R. Nazmutdinov, and E. Spohr, “A model for proton transfer to metal electrodes,” J. Phys. Chem. C, vol. 112, pp. 10814–10826, 2008.
[2] F. Wilhelm, W. Schmickler, and E. Spohr, “Proton transfer to charged platinum electrodes. A molecular dynamics trajectory study,” J. Phys.: Condens. Matter, vol. 22, p. 175001, 2010.
[3] F. Wilhelm, W. Schmickler, R. Nazmutdinov, and E. Spohr, “Modeling proton transfer to charged silver electrodes,” Eletrochim. Acta, vol. 56, pp. 10632–10644, 2011.
[4] W. Schmickler, F. Wilhelm, and E. Spohr, “Probing the temperature dependence of proton transfer to charged platinum electrodes by reactive molecular dynamics trajectory studies”, Electrochim. Acta 101, 341, 2013.
This work was supported by Deutsche Forschungsgemeinschaft through Collaborative Research Group FOR1376 “Elementary Reaction Steps in Electrocatalysis: Theory meets Experiment” and through the Cluster of Excellence RESOLV (EXC 1069).
Electrode/Electrolyte Interface with Various Redox Couples
Authors: Frackowiak Elzbieta , Menzel Jakub , Meller Mikolaj , Fic Krzysztof 
Published: February 2020

Typical electrostatic attraction of ions is at the origin of capacitance, however, some faradaic reactions may occur at electrode/electrolyte interface called pseudocapacitive phenomena. Such effects can be initiated from electrode but also from solutions with electroactive species (iodides, bromides, vanadium compounds, di-hydroxybenzenes etc.). Redox reactions are strongly affected by thermodynamics; Pourbaix diagrams indicate range of potential values where faradaic reactions take place. In typical two-electrode capacitor positive and negative electrode quite often operate not equally. One electrode can work in the very narrow range of potentials, e.g. iodides, bromides, di-hydroxybenzenes (0.1-0.4V) giving very high capacitance values (>1000 F/g) whereas the second one operates in the wide voltage limit but supplying moderate capacitance (ca. 100 F/g). Unfortunately electrode with smaller capacitance will affect a total capacitor performance. Selection of two various and well matched pseudocapacitive materials enables to optimize system. Asymmetric configuration with two different redox couples offers interesting capacitor performance with good cycling.
A few examples of pseudocapacitive phenomena originated from electroactive species present in electrolyte will be shown. Reactions with cerium-based autocatalytic redox shuttle for brominated species oxidizing malonic acid will be also presented as example of oscillating systems. They can serve as great source of pseudocapacitance and may significantly enhance total capacitance of the system. Detailed physicochemical and electrochemical characterization of electrode materials supported by modelling will reflect the role of texture, structure, conductivity of materials as well as concentration of species in electrolytic solutions on capacitor performance.

Acknowledgements

The authors would like to acknowledge a financial support from Swiss-Polish project INGEC.
A Study on the Oxygen Redox Reduction in Ionic Liquid-Based Electrolytes for Li/O2 Battery Application
Authors: Soavi Francesca , Monaco Simone , Arbizzani Catia , Mastragostino Marina 
Published: February 2020

Low volatility, thermal and electrochemical stability and good conductivity of ionic liquids (ILs) make them “key electrolytes” for the development of Li/O2 batteries which are considered the most promising high-energy systems for a market success of electric vehicles of long driving range. Particularly, hydrophobic pyrrolidinium salts of bis(trifluoromethanesulfonyl)imide feature a high stability toward superoxide that is formed during the discharge/recharge of Li/O2 batteries. Under the European LABOHR Project, the oxygen redox reaction (ORR) and O2 diffusion coefficient and solubility, which are crucial parameters for Li/O2 battery operation, have been investigated in such ILs and related to the physical-chemistry properties of the electrolytes. It has also been demonstrated that ILs provide a real possibility for the development of rechargeable Li/O2 batteries that can safely operate even above room temperature. The main achievements of this study are here reported and discussed

Acknowledgement

Work funded by the European Commission in the 7th Framework Programme FP7-2010-GC-ELECTROCHEMICAL STORAGE, under contract no. 265971 “Lithium-Air Batteries with split Oxygen Harvesting and Redox processes” (LABOHR). All the partners of the LABOHR Project are acknowledged for the fruitful discussions on Li/O2 batteries with ionic liquids.

References

[1] www.labohr.eu
[2] S. Monaco, A. M. Arangio, F. Soavi, M. Mastragostino, E. Paillard, S. Passerini, Electrochimica Acta 83 (2012) 94–104.
[3] F. Soavi, S. Monaco, M. Mastragostino, Journal of Power Sources 224 (2013) 115 – 119.
[4] S. Monaco, F. Soavi, M. Mastragostino, J. Phys. Chem. Lett. 4 (2013) 1379−1382.
Spectroscopy of Metal/Electrolyte Interfaces
Authors: Wandelt Klaus R. 
Published: February 2020

It is still a long way to reach the same holistic understanding of properties and processes at metal/ electrolyte interfaces as has been reached for surfaces in ultrahigh vacuum (UHV). In order to over-come this backlog i) more surface physisists should venture to "interfacial electrochemistry", because ii) new analytical techniques need to developed which replace all particle beam based methods which work successfully only in vacuum.
In this lecture I will present and discuss investigations of several electrochemical interface pheno-mena as they occur in electro-catalysis, anion-adsorption, metal-deposition, molecular self-assembly, structural phase transitions, etc., using a number of in-situ methods like various modes of optical spectroscopy (IRRAS, RAS, etc.), X-ray diffraction (XRD) and scanning tunneling microscopy/ spectros-copy (STM/STS) as well as (still unavoidably) ex-situ methods like electron spectroscopies (XPS; AES), low energy electron diffraction (LEED) and ion scattering spectroscopy (ISS). As an example Fig.1 shows EC-STM images and IRRAS spectra of a) the "stripe-structure" and b) the "cavitand-structure" of dibenzyl-viologen molecules adsorbed on Cu(100) in HCl-solution. XPS proves the monocationic [dicationic] state of the molecular building blocks in a) [b)], while IRRAS enables a structural refine-ment of the orientation of the individual molecular cations in the respective structure (see models).
References
[1] T.-D. Pham, K. Wandelt, P. Broekmann, Chem. Phys. Chem. 8 (16) (2007) 2318-2320
[2] M.Röefzaad, PhD-thesis, Univ. Bonn, Germany; and M.Röefzaad, K.Wandelt, in preparation

Fig. 1 EC-STM images and IRRAS spectra of a) the "stripe-structure" and b) the "cavitand-structure" of dibenzyl-viologen adsorbed on Cu(100) in HCl-solution (see text)
Spectroscopic and Electrochemical Studies of Reduction Reactions for Remediation and Batteries
Authors: Gewirth Andrew 
Published: February 2020

We report on spectroscopic and electrochemical stress studies of reduction reactions relevant for batteries and remediation.
Silver is an effective electrocatalyst for the reduction of carbon dioxide to carbon monoxide and other products. Carbon-supported organometallic complexes of Ag with nitrogen-based ligands have been shown to effectively reduce CO2 with performance comparable to that of carbon-supported Ag alone, with increased Faradaic efficiency and less H2 production. The great decrease in the amount of Ag loading required makes these complexes attractive as CO2 reduction catalysts. We employ in situ surface-enhanced Raman spectroscopy (SERS) in order to investigate the mechanism by which CO2 reduction proceeds at silver electrodes in the presence of these nitrogen-based ligands, as well as the structural interactions of the Ag-ligand complex at the electrode interface. We show that an effect of surface decoration is to decrease the affinity of the CO product for the Ag surface, leading to higher rates of CO production.
We also use spectroscopic methods to assess the reduction of nitrate and dinitrogen on lithium electrode surfaces. We show that in contrast to the expected formation of lithium nitride, the material on the Li electrode is more complex, yielding an oxynitride species the presence of which is responsible for the partial passivation on the Li surface under these conditions. We contrast the behavior of nitrate on Li with that occurring on Cu under milder conditions.
Nanotubes for Osmotic Energy Harvesting
Authors: Poncharal Philippe , Siria Alessandro , Biance Anne-Laure , Fulcrand Rémy , Blase Xavier , Purcell Steve Thomas , Bocquet Lydéric 
Published: February 2020

New paradigms for fluid transport are expected to emerge from the confinement of liquids at the nanoscales [1- 3], with potential breakthroughs in ultra-filtration, desalination, and energy conversion [4]. Nevertheless, advancing the fundamental understanding of fluid transport at the smallest scales requires mass and ion dynamics to be ultimately characterized across an individual channel to avoid averaging over many pores.
To this end, a major challenge for nanofluidics consists in building distinctive and well-controlled nano-channels, amenable for systematic exploration of their properties. In this work [5] we describe the elaboration and exploitation of a new hierarchical nanofluidic device, made of a unique boron-nitride (BN) nanotube that transpierces an ultrathin membrane and connects two fluid reservoirs. Such a transmembrane geometry allows the versatile exploration of fluidic transport through a single nanotube under diverse forcing, including electric fields, pressure drops, and chemical gradients.
Using this device, we discover huge osmotically-induced electric currents generated by salinity gradients, exceeding by two orders of magnitude their pressure-driven counterpart. We show that this result originates from the anomalously high surface charge carried by the BN internal surface in water at large pH, which was independently quantified from conductance measurements. The nano-assembling route using nanostructures as building blocks opens new perspectives to explore fluid, ionic and molecule transport at nanoscales, paving the way towards biomimetic functionalities. Our results furthermore suggests that boron-nitride nanotubes could be advantageously exploited as membranes for osmotic power harvesting under salinity gradients, making it a prime renewable source of energy.
[1] W. Sparreboom, et al., Nature Nano, 4, 713-720 (2009).
[2] L. Bocquet and E. Charlaix, Chem. Soc. Rev. 39, 1073-1095 (2010).
[3] J. C. Rasaih, et al., Annu. Rev. Phys. Chem. 59 713-740 (2008).
[4] B. E. Logan and M. Elimelech, Nature, 488 313-319 (2012).
[5] A. Siria, et al. Nature, 494, 455-458, (2013).
Carbon Nanotube Thin Films and Hybrid Structures for Supercapacitor and Fuel Cell Applications
Authors: Bekyarova Elena , Palanisamy Ramesh , Itkis Mikhail E , Haddon Robert C 
Published: February 2020

The development of low cost and environmentally friendly energy conversion andstorage systems is currently of the utmost priority. Here we discuss the impact of chemical design of carbon nanomaterials on their performance as active materials for supercapacitor and catalyst support for fuel cell applications.
Chemical modification of single-walled carbon nanotubes (SWNTs) and graphene, is a powerful means to improve the charge capacitance of the materials. By introducing oxygen-containing groups the gravimetric capacity of SWNTs and graphene can be doubled. Furthermore, the combination of 1D SWNTs and 2D graphene affords hybrid structures with enhanced synergistic electrochemical performance.
We also demonstrate the advantages of functionalized SWNTs for the fabrication of SWNT thin film catalyst support layers in polymer electrolyte membrane fuel cells (PEMFCs). Introducing an optimum level of carboxylic groups in the SWNTs allows the fabrication of SWNT-based PEMFC with efficient Pt catalyst utilization. This offers an attractive route to the manufacture of highly efficient fuel cells that meet some of the US DOE 2017 technical targets.
Carbon Nanomaterials As Metal-Free Catalysts for Energy Conversion
Authors: Dai Liming 
Published: February 2020

Oxygen reduction reaction (ORR) is an important process in many fields, including energy conversion (fuel cells, metal-air batteries), corrosion, and biosensing. Although Pt nanoparticles have been regarded as the best electrocatalyst for ORR in fuel cells, they are still suffered from multiple problems. For instance, Pt-based cathode electrocatalysts are susceptible to the cross-over effect, long-term instability, and CO poisoning. Furthermore, the high cost of Pt, together with its limited reserve in nature, has been shown to be the “bottleneck” for large-scale commercialization of the fuel cell technology.
Along with the recent intensive research efforts in reducing or replacing Pt-based electrode in fuel cells, we have previously demonstrated that vertically aligned nitrogen-doped carbon nanotubes (VA-NCNTs) produced by pyrolysis of iron (II) phthalocyanine could actively catalyze ORR via a four-electron process free from the crossover and CO poisoning effects with a 3-time higher electrocatalytic activity and better long-term durability than that of commercially available Pt/C electrocatalysts. Similar ORR electrocatalytic activity was also observed for nitrogen-doped graphene (N-graphene). On the basis of these experimental observations and quantum mechanics calculations, we have attributed the observed ORR catalytic activities of the VA-NCNTs and N-graphene to the electron-accepting ability of the chemically-bonded nitrogen atoms, which create a net positive charge (via intramolecular charge-transfer) on adjacent carbon atoms in the nanocarbon structures to readily attract electrons from the anode for facilitating the O2 adsorption and ORR on the cathode. These findings prompted us to develop carbon-based metal-free ORR catalysts by positively charging carbon atoms in the nitrogen-free carbon nanotubes and graphene plane through intermolecular charge-transfer with functionalized/adsorbed moieties. In particular, we have recently used poly(diallyldimethylammonium chloride), PDDA, as an electron acceptor for functionalizing N-free carbon nanotubes and graphene to show remarkable electrocatalytic activity toward ORR. We have also demonstrated that carbon nanotubes and graphene co-doped with N and B showed a synergetic effect toward ORR, and that nitrogen-doped 3D graphene foam (N-GF) could be used as a metal-free electrocatalyst for the reduction of triiodide to replace the Pt cathode in dye-sensitized solar cells (DSSCs). In this talk, we will summarize some of our work on the metal-free ORR catalysts based on carbon nanomaterials, along with an overview on the recent developments in this exciting field.
Carbon Nanostructures: Interactions with Biological Systems
Authors: Da Ros Tatiana 
Published: February 2020

The interest on functionalized carbon nanostructures in the nanomedicine field is constantly increasing and many different approaches have been used to study the interactions and the effects of these nanomaterials on cells.
In this contribution we will mainly focus our attention on the analysis of genome expression of a cell line, comparing the results obtain before and after the treatment with two compounds, and taking into account the in vitro results obtained previously using traditional cytotoxicity test.
Invited Presentation: Electrochemically Induced Stresses in Energy Related Materials
Authors: Sheldon Brian W. 
Published: February 2020

The volume changes that are associated with composition changes in a solid can induce significant stresses, when these expansions or contractions are physically constrained. These phenomena are important in a variety of energy-related materials, where they lead to complex interactions between electrochemical and mechanical driving forces. We have employed in situ measurements of these stresses along with a variety of other in situ and ex situ characterization methods, to obtain critical information about how the relevant mechanisms operate in different types of materials. One example is ceria electrolytes in solid oxide fuel cells, where oxygen potential gradients across the electrolyte can lead to large stresses. These stresses, caused by differences in the oxygen content of the ceria, are significantly enhanced by grain boundary contributions that can be interpreted with space charge effects.
In Li ion battery (LIB) electrodes, Li insertion and removal can also lead to very large stresses and complex deformation behavior. One area of interest here is the solid-electrolyte interphase (SEI) layer, where we have recently shown that substantial near-surface stresses occur during SEI formation on graphitic carbon anodes. These results imply that stresses can be engineered during SEI formation, to enhance the stability of these critical passivation layers. Another concern in is the mechanical integrity of interfaces in composite electrode structures. Here, we have used patterned thin film structures to understand the response of bi-material interfaces during Li cycling. The integrity of these interfaces is critical for cycling stability and capacity retention in rechargeable Li ion batteries.
Oxygen Nonstoichiometry, Defect Structure and Chemical Expansion of Advanced Perovskite and Double Perovskite Oxides
Authors: Zuev Andrey , Sereda Vladimir , Ivanov Ivan , Malyshkin Dmitry , Tsvetkov Dmitry 
Published: February 2020

Perovskites and double perovskites based upon substituted oxides LnBO3-δ and LnBaB2O6-δ, respectively, where Ln=lanthonoid, B=3d-transition metal, are the state-of-the-art materials for a variety of different devices for moderate high temperature applications such as solid oxide fuel cells (SOFCs) and mixed ionic and electronic conducting (MIEC) membranes. The unique feature of the oxides is their ability to undergo both thermal expansion and that induced by the defects of oxygen nonstoichiometry in the oxide lattice. The latter is chemical or defect-induced expansion. This property is extremely sensitive to the defect structure of the oxide material. Despite it is generally recognized that point defects are responsible for chemical expansion its mechanism is still controversial topic. Different reasons such as changing Coulomb forces, atomic packing, local structure, preferred coordination, association between dopants and vacancies and others are discussed in this respect. If electronic defects have localized nature then another reason may lead to chemical expansivity. Within the framework of such assumption the oxygen vacancy formation is accepted to be accompanied by the reduction of 3d-metal cations. As a result, average size of the B-site cations increases due to the apparent substitution of “large” B(z-1)+ for smaller Bz+. Oxygen vacancy formation may also contribute to chemical expansion observed due to a change of coulomb interaction between ions. If oxide lattice chemical expansion is caused by a change of mean ionic radius due to reduction of most reducible cation then a model allowing its calculation can be developed. In order to do it the following assumptions should be accepted. (i) A closely packed lattice of oxide is formed by ions with rigid spheres. (ii) Expansion in each of three space directions is of equal value. The latter seems to be valid only for oxides with pseudo-cubic structure such as perovskites but this is not the case for layered double perovskite.
The model proposed for pseudo-cubic oxides was shown in this work to coincide completely with experimental data on chemical expansion for the perovskite La0.7Sr0.3Co0.9Fe0.1FeO3-δ. On the contrary, chemical expansion of PrBaCo2O6-δ along
a
axis and contraction along
c
axis were found to compensate each other completely in the double perovskite and, therefore, its volume (overall) chemical expansion becomes negligible. As a result the cell volume linearly increases with temperature in air contrary to simple cubic perovskites such as La0.7Sr0.3Co0.9Fe0.1O3-δ.
Tunable Carbon Nanotube Mesh Fabricated Via Surfactant Assisted Direct Deposition for High Performance Transparent Electrodes
Authors: Abdel-Fattah Tarek M , Dushatinski Thomas 
Published: February 2020

This study involved the deposition of multi-walled carbon nanotubes (MWCNTs) onto plastic, polyethylene terephalate (PET), substrates. The MWCNTs were suspended in an aqueous solution via the assistance of an ionic surfactant, sodium dodecyl sulfate (SDS). The SDS/MWCNT complexes in solution were attracted to the PET substrate because of electrostatic forces that were demonstrated by contrasting poor coverage on glass substrates.
The solutions were deposited onto the PET films and allowed to interact for different amounts of time resulting in films that had decreasing resistivity and transparency because of increasing thicknesses.
The ratio of SDS to MWCNT to solvent, water in this case, was from an optimized MWCNT colloid study.1 The ratio used was 10:1:1000 respectively by weight. The excess surfactant was removed at different times using the spin coating technique. Films were then rinsed in water to remove excess surfactant caught in-between the nanotubes in the mesh and then dried in an oven.
The best thin film had an average resistivity of 110 Ω/sq at 81% transmittance at 550 nm and a thickness of ± 2 um. Their performance is similar to indium tin oxide thin films as cathodes. The MWCNT and SDS composite thin films will be tested in optoelectronic applications such as solar cells and liquid crystal displays.
References

1 Rastogi, R.; Kaushal, R.; Tripathi, S.; Sharma, A.; Kaur, I.; Bharadwaj, L. Comparative study of carbon nanotube dispersion using surfactants. 2008, J. Colloid Interface Sci. 328, 421-428.

2 Jo, J.; Jung, J.; Lee, J.; Jo, W. Fabrication of Highly Conductive and Transparent Thin Films from Single Walled Carbon Nanotubes Using a New Non-ionic Surfactant via Spin. 2010, ACS Nano. 4 (9), 5382-5388.