bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spontaneous Phase Segregation in Bare Palladium-Platinum Nanoparticles Evidenced By Superior Hydrogen Absorption
Authors: Januszewska Aneta , Dercz Grzegorz , Lewera Adam , Jurczakowski Rafal Robert 
Published: February 2020

Palladium Platinum bimetallic alloys are widely used in heterogeneous catalysis as active components for oxygen reduction reaction, anodes in low temperature fuel cells and hydrogenation of aromatic compounds in fuels. Pd-Pt catalysts often operate at elevated temperatures, for example in catalytic converters for automobile exhausts. Under such conditions segregation/alloying is a particularly important issue. However, in most experimental studies on Pd-Pt nanoparticles the homogeneous alloying is consistently reported or a priori assumed.
Specific interactions of surfaces with monolayers of foreign adatoms (metals and nonmetals) are generally known as a particularly sensitive surface probes [1], among which copper and hydrogen underpotential deposition (UPD) are the most widely used. However, by using this approach little is known about the nanoparticle interior. In contrast, chemical potential of absorbed hydrogen does provide deep insight into the homogeneity on the atomic scale since it is determined by near interactions between metal atoms and absorbed hydrogen occupying interstitials.
In this study we have shown that Pd-Pt nanoalloys are much more susceptible to segregation than their bulk counterparts. The spontaneous segregation and chemical ordering of Pd-Pt nanoalloys was evidenced by hydrogen absorption enhanced nearly by three orders of magnitude with respect to random Pd-Pt alloys [2].
Chemical surface and bulk compositions of the nanoalloys were established by using XPS and ICP-MS, respectively. Carbon monoxide adsorption/oxidation was used as a surface probe and as an indicator of catalytic properties of investigated bimetallic nanoparticles. Hydrogen sorption properties of these alloys were investigated by means of hydrogen UPD and Hydrogen insertion in acidic solutions by using classical transient electrochemical methods. Hydrogen absorption isotherms exhibited a markedly enhanced hydrogen solubility and distinct phase transition in the Pd-Pt-H systems that is absent in Pd-Pt alloys with random atom distribution.
We also report the highest hydrogen sorption in Pd80Pt20 alloy exceeding H/(Pt+Pd)=0.5 at the ambient temperature and hydrogen pressure, which additionally emphasizes the importance of both surface purity and segregation on catalysis and hydrogen storage. Our results clearly show that phase segregation is an extremely important factor that is frequently overlooked in experimental studies yet quite crucial for practical applications.
Literature
[1] Solla-Gullón, J.; Rodríguez, P.; Herrero, E.; Aldaz, A.; Feliu, J. M. Phys. Chem. Chem. Phys. 2008, 10, 1359-1373.
[2] Januszewska, A.; Dercz, G.; Lewera, A.; Jurczakowski, R. J. Phys. Chem. C, Submitted.
Relation Between Thermodynamic and Kinetics Aspects of Pt Deposition Via Slrr and Resulting Properties of Catalyst Monolayers
Authors: Brankovic Stanko , Yuan Qiuyi 
Published: February 2020

The deposition method based on surface limited replacement reaction i.e. galvanic displacement of under potentially deposited (UPD) metal monolayers has been extensively used for preparation of highly active catalysts monolayers1-[i],[ii],[iii][iv]. The physical and chemical behavior of these monolayers is altered due to different structural and electronic effects dominating their properties. In the case where ligand (substrate) effect is weak, their properties are predominantly affected by the level of coherent strain.
The two dimensional Pt submonolayers/nanoclusters on Au(111) and Pd(hkl) were used as model system to study size/strain effect on catalyst monolayer properties. The probe ion/molecule was CO and Pb2+, and the Pt submonolayers were obtained by galvanic displacement of Cu UPD monolayers using surface limited red-ox replacement process. The morphology of Pt monolayers was studied by scanning tunneling microscopy and statistical image processing. The electrosorption characteristics of Pt submonolayers were studied using SNIFTIR, STM and conventional electrochemical methods.
The results indicate that Pt submonolayers have quite different electrosorption properties as compared to Pt bulk electrode. In both cases, with strong (Pd(111)) and weak (Au(111)) ligand effect of substrate, a lower reactivity of Pt submonolayers is observed as compared to Pt(111) electrode. In the case of CO adsorption on Pt/Pd(111), the spectroscopic and electrochemical data indicate weaker bond than on both bulk Pt(111) and Pd(111) electrodes. In the case of Pb2+adsorption, (UPD), the Pt sub-monolayers remain passive for UPD process until several hundred milivolts more negative potentials as compared to Pb UPD on Pt(111). These results suggest that lateral strain developed in Pt submonolayers/nanoclusters, which is function of their size, is a dominant force determining their electrosorption behavior.
The presented work correlates the theoretical analysis of the size effects on the active strain in different Pt submonolayer catalysts with their experimentally observed electrosorption properties.

[#] SRBrankovic@uh.edu

[[i]] J. Greeley, J. K. Nørskov, and M. Mavrikakis, Annu. Rev. Phys. Cehm., 53, (2002) 319.
[[ii]] M. Mavrakakis, B. Hammar, and J.K. Nørskov, Phys. Rev. Lett., 81, (1998) 2819.
[[iii]] A. Schlapka, M. Liseihka, A. Gross, U. Kasberger, and P. Jakob, Phys. Rev. Lett., 91, (2003) 016101.
[[iv]]E. Kamshoff, E. Hahn, and K. Kern, Phys.
Rev. Lett., 73, (1994) 704.
Immobilization of Glucose Oxidase on 4-(pyrrole-1-yl) Benzoic Acid Functionalized Carbon Nanotubes for Direct Electrochemistry and Glucose Sensing
Authors: Kowalewska Barbara , Jakubow Katarzyna 
Published: February 2020

In recent years, carbon nanotubes (CNT) have gained considerable attention, because of their remarkable electronic and mechanical properties, which have made them extremely attractive for a wide range of sensing applications from structural materials to nanoelectronic components. The ability of CNT-modified electrodes to promote electron transfer reactions has been documented in connection with important biomolecules [1]. Our goal is to explore new applications of CNT as an electrode material in facilitating the electron transfer between enzyme molecule and electrode in the bioelectrocatalytic system for glucose oxidation that is of potential utility for bioelectronic devices such as biosensors and biofuel cells.
Our research focuses on the direct electrochemical performance of glucose oxidase (GOx) immobilized on 4-(pyrrole-1-yl) benzoic acid (PyBA) modified multi-walled carbon nanotubes (CNTs). GOx is a homodimer containing two tightly bound flavin adenine dinucleotide (FAD) redox centers embedded deeply in the enzyme [2]. Modification of carbon nanostructures allow to obtain thin and organized films, causing a rapid and effective transfer of electrons between the active center of the biocatalyst (GOx) and the electrode surface. The presence of PyBA in our composite film significantly improves their stability and introduces new functional groups that have great importance in the enzyme immobilization process onto the CNTs-modified electrode [3].
In this work stable immobilization and direct electron transfer of glucose oxidase were achieved on the composite film modified glassy carbon electrode. The resulting electrode gave a well-defined redox peaks with a formal potential of about −440 mV (vs. Ag/AgCl) in 0.1 phosphate buffer solution pH=7.0. The electron transfer rate constant was estimated to be 3.15 s-1, due to the combined contribution of CNTs/PyBA and GOx. Furthermore, the method for detecting of glucose was proposed based on the decrease of oxygen caused by the enzyme-catalyzed reaction between GOx and glucose. The low calculated apparent Michaelis–Menten constant (KM
app) was 10.2 mM, implying the high enzymatic activity and affinity of immobilized enzyme for glucose. It can reasonably be expected that this observation might hold true for other noble carbon nanostructure-electroactive protein systems, providing a promising platform for the development of biosensors and biofuel cells.
References
[1] J.J.Gooding, R.Wibowo, J. Liu, W. Yang, D. Losic, S. Orbons, F.J. Mearns, J.G. Shapter, D.B. Ilibbert, J. Am. Chem. Soc. 125 (2003) 9006.
[2] H.J. Hecht, H.M. Kalisz, J. Hendle, R.D. Shmid, D.Schomburg, J. Mol. Biol. 229 (1993) 153.
[3] B. Kowalewska, M. Skunik, K. Karnicka, K. Miecznikowski, M. Chojak, G. Ginalska, A. Belcarz, P.J. Kulesza, Electrochim. Acta 53 (2008) 2408.
Oxygen Transport in Perovskite-Type Materials for SOFCs Cathodes: What Can We Learn from Quantum Mechanics
Authors: Muñoz-García Ana Belén , Pavone Michele , Ritzmann Andrew Marc , Carter Emily A. 
Published: February 2020

Effective, rational design of innovative, low-cost materials with high oxygen reduction reaction (ORR) catalytic activity at intermediate temperatures (ITs) requires a deep understanding of the underlying reaction mechanisms of oxygen incorporation and diffusion in solid oxide fuel cell (SOFC) cathodes.
We use state-of-the-art first-principles calculations in order to gain atomic scale insights into the relationships between composition, structure, and transport properties of traditional perovskite-type cathode materials ABO3 (A=La, Sr; B=Mn, Fe, Co, Cr) and the new, promising Sr2Fe1.5Mo0.5O6-δ
electrode. Specifically, we study the factors that govern bulk oxide ion diffusion in these materials, namely, the oxygen vacancy formation energy and migration barrier, as well as the surface features that allow the dissociation and incorporation of oxygen.
Beyond quantitative agreement with measurements, our results provide new insights into the origin of the observed material behavior. The electronic structure of the B-site transition metal, the A-site cation charge and the B-O bond nature are the main features that determine perovskite cathode performance. The subtle interplay of long-range electrostatics and local electronic effects is ultimately responsible for vacancy formation, ion and transport, and electronic conductivity. All these properties and processes can be fine-tuned by appropriate choices of A- and B-site constituent elements and aliovalent substitutions at each site. The ratio and nature of the additives are crucial for obtaining the desired performance.
Our findings provide foundational and systematic understanding of perovskite bulk and surface properties and of the emergent ORR performance so that new generations of effective SOFC cathodes can be developed.
[1] Muñoz-García, A. B.; Pavone, M.; Carter, E. A. Chem. Mater. 2011, 23, 4525–4536.
[2] Pavone, M.; Ritzmann, A. M.; Carter, E. A. Energy Environ. Sci. 2011, 4, 4933–4937.
[3] Muñoz-García, A. B.; Bugaris, D. E.; Pavone, M.; Hodges, J. P.; Huq, A.; Chen, F.; zur Loye, H.-C.; Carter, E. A. J. Am. Chem. Soc. 2012, 134, 6826–6833
[4] Muñoz-García, A. B.; Pavone, M.; Ritzmann, A. M.; Carter, E. A. Phys. Chem. Chem. Phys 2013, 15, 6250–6259.
[5] Ritzmann, A. M.; Muñoz-García, A. B.; Pavone, M.; Keith, J. A.; Carter, E. A. Chem. Mater. 2013, 25, 3011–3019.
[6] Ritzmann, A. M.; Muñoz-García, A. B.; Pavone, M.; Keith, J. A.; Carter, E. A. MRS Commun. 2013, 3, 161–166.
Chronoamperometric In Situ Measurement of the Specific Conductivity of a Thin Film on the Disc Electrode Surface
Authors: Vorotyntsev Mikhail A , Konev Dmitry V 
Published: February 2020

A new method to measure both the total resistance and the specific conductivity of a thin film (for the current flow in the normal direction) is proposed [1].
It is assumed that the film has been deposited on the surface of a disc electrode (in static or rotating conditions). A relatively small diameter of the disc is preferable to ensure the maximal uniformity of the film along the surface. The thickness of the film, Lf, should be sufficiently small compared to the disc radius, ro, but it should cover the surface in a uniform manner. The conductivity properties of the deposited material may be isotropic or anisotropic (different in the normal and tangential directions).
The primary and secondary distributions of the electric potential and the current after a small-amplitude potential step have been analyzed for such a film-coated electrode in contact with an electrolyte solution, CE and RE being located sufficiently far from the disc electrode (WE). The three-dimensional (3D) character of these distributions inside the solution has been taken into account.
Analytical expressions have been derived for the overall short-time resistance of the system, Rtot, with taking into account the contributions of both the solution and the film. Due to the 3D effect this quantity for the primary distribution is not equal to the sum of the short-time resistances of these components of the system, Rs for solution and Rf for the film. Analytical formulas have been deduced, allowing one to calculate immediately the film resistance, Rf, on the basis of measured values of Rtot and Rs. Then, the specific conductivity of the film, kf, is found from relation: kf = Lf / Rf pro
2.
Both parameters of the film may be determined by this method for a set of electrode potential values, see Fig.1 for a poly(titanocene-propyl-pyrrole) film.
The merits of this procedure to determine the high-frequency transport parameters are: 1) film deposition at a small surface area (but still macroscopic) substrate; 2) no lower restriction for the film thickness (except for their uniformity); 3) in situ measurements inside the conventional cell; 4) non-destructive procedure (film may be used for further texts); 5) simple data treatment; 6) weak effects of local film's imperfections, etc.
Support of RFFI (projects 09-03-01172 and 10-08-00847) is acknowledged.
Fig. 1 Dependence of the specific conductivity of the poly(titanocene-propyl-pyrrole) film on the potential.
[1]. M.A. Vorotyntsev, D.V. Konev / Electrochim. Acta 56 (2011) 9105– 9112
Dielectric Properties of Hydrated Perfluorosulfonic acid membranes
Authors: Minutolo Anthony , Wang Chen , Paddison Stephen , Sangoro Joshua 
Published: February 2020

Broadband Dielectric Spectroscopy is employed to investigate the link between hydrated morphology, local water dynamics and charge transport in a series of commercially available Perfluorosulfonic Acid (PFSA)

membranes of different equivalent weights and hydration levels[1-2]. Different experimental set-ups are used to determine dielectric properties of both dry and hydrated membranes in a wide frequency range spanning more than 11 orders of magnitude. The dielectric spectra are dominated by long-range proton conduction on the low frequency regime and local water dynamics at higher frequencies. The results are discussed within the framework of recent studies of charge transport in nano-confined membranes.

References

1. K.-D. Kreuer, M. Schuster, B. Obliers, O. Diat, U. Traub, A. Fuchs, U. Klock, S. J. Paddison and J. Maier, J. Power Sources, 178, 499 (2008).
2. G. A. Giffin, G. M. Haugen, S. J. Hamrock, and V.D. Noto, Journal of the American Chemical Society,

135
(2), 822-834 (2013).
Effect of the Electrolyte Formulation on the Performances of Edlc and Li-Ion Batteries
Authors: Ghamouss Fouad , Zhang Wanjie , Dahbi Mouad , Jacquemin Johan , Tran-Van François , Monconduit Laure , Martinez Hervé , Dedryvère Rémi , Lemordant Daniel 
Published: February 2020

One of the most important components in electrochemical storage devices (batteries and supercapacitors) is undoubtedly the electrolyte. The basic function of any electrolyte in these systems is the transport of ions between the positive and negative electrodes. In addition, electrochemical reactions occurring at each electrode/electrolyte interface are the origin of the current generated by storage devices. In other words, performances (capacity, power, efficiency and energy) of electrochemical storage devices are strongly related to the electrolyte properties, as well as, to the affinity for the electrolyte to selected electrode materials. Indeed, the formulation of electrolyte presenting good properties, such as high ionic conductivity and low viscosity, is then required to enhance the charge transfer reaction at electrode/electrolyte interface (e.g. charge accumulation in the case of Electrochemical Double Layer Capacitor, EDLC). For practical and safety considerations, the formulation of novel electrolytes presenting a low vapor pressure, a large liquid range temperature, a good thermal and chemical stabilities is also required.
This lecture will be focused on the effect of the electrolyte formulation on the performances of electrochemical storage devices (Li-ion batteries and supercapacitors). During which, a summary of the physical, thermal and electrochemical data obtained by our group, recently, on the formulation of novel electrolyte-based on the mixture of an ionic liquid (such as EmimNTf2 and Pyr14NTf2) and carbonate or dinitrile solvents will be presented and commented. The impact of the electrolyte formulation on the storage performances of EDLC and Li-ion batteries will be also discussed to further understand the relationship between electrolyte formulation and electrochemical performances. This talk will also be an opportunity to further discuss around the effects of additives (SEI builder: fluoroethylene carbonate and vinylene carbonate), ionic liquids, structure and nature of lithium salt (LiTFSI vs LiPF6) on the cyclability of negative electrode to then enhance the electrolyte formulation. For that, our recent results on TiSnSb and graphite negative electrodes will be presented and discussed, for example 1,2.
1-C. Marino, A. Darwiche1, N. Dupré, H.A. Wilhelm, B. Lestriez, H. Martinez, R. Dedryvère, W. Zhang, F. Ghamouss, D. Lemordant, L. Monconduit “ Study of the Electrode/Electrolyte Interface on Cycling of a Conversion Type Electrode Material in Li Batteries” J. Phys.chem. C, 2013, 117, 19302-19313
2- Mouad Dahbi, Fouad Ghamouss, Mérièm Anouti, Daniel Lemordant, François Tran-Van “Electrochemical lithiation and compatibility of graphite anode using glutaronitrile/dimethyl carbonate mixtures containing LiTFSI as electrolyte” 2013, 43, 4, 375-385.
Templating Effect of Polymeric Electrolytes on the Electropolymerization of Aniline
Authors: Nekrasov Alexander A. , Gribkova Oxana L. , Isakova Alexandra A. , Zolotarevsky Victor I. , Ivanov Victor F. , Vannikov Anatoly V. 
Published: February 2020

Preparation of polyaniline (PANI) in the presence of polymeric electrolytes is known to produce the polymer with improved characteristics such as mechanical properties, thermal stability, adherence, controlled morphology, wide pH-range of electroactivity, etc. This contribution describes the results of systematic studies on the influence of the structure of water-soluble polymeric sulfonic acids on PANI electrodeposition and properties. The course of polymerization in potentiostatic, galvanostatic and potential sweep regimes was traced by chronoamperometry, chronopotentiometry, cyclic voltammetry and in situ AFM measurements. It was shown that the structure of polyacid, namely, the rigidity of the polymer backbone, the distance between sulfonic groups on the backbone, the length and rigidity of the side chains containing sulfonic groups, strongly affect the onset potential of aniline oxidation, the character and the rate of the initial stages of PANI/polyacid film growth. The in situ AFM studies performed during potentiostatic polymerization showed that the structure of polyacid (primarily the backbone rigidity) has a direct influence on the shape of PANI “nuclei” and the morphology of the film in the early stages of the electropolymerization (Fig. 1). The obtained films were also characterized by UV-Vis-NIR spectroscopy and spectroelectrochemistry and cyclic voltammetry.
This work was supported by the Russian Foundation for Basic Research (grant No.12-03-01087).
Simultaneous Electrochemical EPR in Probing the Oxygen Reduction Mechanism of Non-Precious Electrocatalysts for PEMFC
Authors: Zhang Congling , Lawton Jamie S. , Foister Shane , Goenaga Gabriel A. , Zawodzinski Thomas A. 
Published: February 2020

The ORR mechanism as catalyzed by non precious metal catalysts to replace Pt based catalysts at the cathode of PEMFC has been controversial for decades, though this category of catalysts has recently achieved remarkable ORR performance.1,2 More understanding of the ORR mechanism is essential to the further improvement of the performance of catalysts of this class. Cu(II) based non precious metal catalysts are advantageous for the study of the ORR mechanism due to their biomimetic significance in mimicking copper oxidases and, when not pyrolyzed to their well defined structure.3

To gain deeper understanding of the ORR mechanism, an in situ electrochemical half cell for EPR has been designed and applied to probe the mechanism of the ORR catalyzed by a Cu(II)-3,5-diamino-1,2,4-triazole based (shown here) and other catalysts. Simultaneous observation of electrochemical behavior and the corresponding Cu(II) EPR signal evolution at different potentials was realized as shown in Figure 1. The intensity of the Cu(II) signal decreases as the potential steps negative because more Cu(II) is reduced to Cu(I) at more negative potentials. In Figure 2, the EPR spectroscopic behaviors of Cu(II) during a cyclic voltammogram are different in the presence and absence of O2, with a shift in potential indicating a complex formation between O2and Cu ions during ORR catalysis. A study of the effects of oxygen concentration will be conducted to estimate the amount of active catalytic sites in the catalyst. A quantitative relationship will be investigated to determine the reaction order of Cu species in the ORR catalysis. Finally, this method will be applied to a number of related non-precious metal catalysts.

Acknowledgements:

The authors gratefully acknowledge the support of theUS DOE Office of Fuel Cell Technology and the office of Naval Research for financial support of this work.

References:

[1]. Proietti, E.; Jaouen, F.; Lefèvre, M.; Larouche, N.; Tian, J.; Herranz, J.; Dodelet, J.-P. Nat. Commun. 2011, 2, 416
[2]. Wu, G.; More, K. L.; Johnston, C. M.; Zelenay, P. Science 2011, 332, 443–7
[3]. Thorum, M. S.; Yadav, J.; Gewirth, A. A. Angew. Chem. Int. Ed. Engl. 2009, 48, 165–7