bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Cobalt-Doped Electrolyte on the Electrochemical Performance of LSCFO/CGO Interfaces
Authors: Baqué Laura Cecilia , Padmasree Karinjilottu , Ceniceros Reyes Mónica Aimee , Troiani Horacio , Arce Mauricio Damian , Serquis Adriana , Soldati Analía 
Published: February 2020

Solid oxide fuel cells (SOFCs) are efficient and environmental friendly devices which directly convert hydrogen and fosil fuels into electric energy. The operation temperature of these devices is mainly determined by the nature of its electrolyte. Conventional SOFCs are composed of yttria based electrolytes requiring operation temperatures around 1000ºC, whereas ceria based electrolytes have allowed reducing the temperature down to the 500-700ºC range. Nevertheless, these materials require sinterization temperatures in the 1300-1600ºC range to achieve complete densification, which produces very large grain sizes and poor mechanical properties. In the last years, several research works have demonstrated that the addition of transition metals oxides is effective in improving the densification and thus, lowering the sinterization temperatures of ceria based electrolytes. Such research works, generally focalize on how the addition of these sintering aids affect the properties (density, sintering temperature, conductivity) of the electrolyte. Nonetheless, it is well established that SOFC performance depends not only on the characteristics and performance of its individual components (i.e. cathode, electrolyte and anode) but also on their interfaces. Hence, a comprehensive study on how the addition of electrolyte sintering aids affects the cell performance is still missing.
In this work, we have studied La0.4Sr0.6Co0.8Fe0.2O3-d/Ce0.8Gd0.2O2-d/La0.4Sr0.6Co0.8Fe0.2O3-d symmetrical cells containing Ce0.8Gd0.2O2-d electrolytes synthesized by a molten salt route [1] with and without Co oxide doping. La0.4Sr0.6Co0.8Fe0.2O3-d nanostructured cathodes with high electrochemical performance [2,3] were deposited by spin coating techniques on both sides of the electrolyte pellets. The assemblies were studied by Electrochemical Impedance Spectroscopy (EIS), X-Ray Diffraction and Transmission and Scanning Electron Microscopy. EIS results indicate that both electrolyte and cathode impedance response are affected by the addition of the sintering aid to the electrolyte, despite using cathodes with similar microstructure according to SEM observations. A possible explanation for such behavior was founded during TEM characterization which reveals the formation of columnar structures at the cathode/electrolyte interface of the cell with cobalt-doped electrolyte. These columnar structures would negatively affect the cell performance hindering the diffusion of oxide ions from the cathode to the electrolyte.
[1] Mendoza-Mendoza E., Padmasree K., Montemayor S. and Fuentes A., J Mater Sci 47 (2012) 6076-6085.
[2] Baqué L, Caneiro A, Moreno MS, Serquis A., Electrochem Commun 10 (2008) 1905-1908.
[3] Soldati A., Baqué L., Troiani H., Cotaro C., Schreiber A., Caneiro A, Serquis A. Int J Hyd Energy 36 ( 2011) 9180-9188.
(Invited) Potential Energy Landscape for Oxygen Vacancy Dynamics in Doped Ceria
Authors: Kim Sangtae 
Published: February 2020

Ionic transport plays a key role in controlling a wide range of properties and processes important for applications such as catalysis, batteries, fuel cells, environmental sensors, and resistive random-access memory devices. For most of these applications, an outstanding need exists for ionically conducting materials with enhanced transport of charge carriers and consequently high conductivities at lower temperatures. The two most important factors that control the hopping transport of charge carriers are their concentration and mobility in the host structure. The effect of charge-carrier concentration on electrical conductivity has been investigated extensively over the last several decades in relation to transport in the bulk as well as near interfaces, and it is well-understood within the framework of microscopic and mesoscopic models of ionic conduction. In contrast, a fundamental understanding of the controlling factors for charge-carrier mobility in ionic conductors remains rudimentary at best, and it necessitates a detailed knowledge of the interactions between the mobile charge carriers and the potential energy landscape (PEL) provided by the immobile host lattice. In this contribution, we provide a comprehensive picture of the PEL for oxygen-vacancy migration in acceptor doped CeO2 based on the results from a combined application of nuclear magnetic resonance (NMR) and electrochemical impedance spectroscopy (EIS). We also present the results of our investigation on the effect of crystallite size on cation coordination environments and oxygen vacancy ordering in micro- and nanocrystalline doped ZrO2 and CeO2 by using high-resolution magic-angle-spinning NMR spectroscopy.
Solid Oxide Membrane for Reduction of Ce0.8Gd0.2O2 and TiO2 in LiCl-Li2o
Authors: Olson Luke Christopher , Garcia-Diaz Brenda Lee , Brinkman Kyle S 
Published: February 2020

A solid oxide membrane was used in a three electrode electrochemical cell to separately reduce, both Ce0.8Gd0.2O2 and TiO2 in molten solution of LiCl-Li2O. The Ce0.8Gd0.2O2 was used as a surrogate for UO2, with the goal of using a similar technique during potential nuclear fuel reprocessing scenarios. The solid oxide membrane was a closed-end yttria stabilized zirconia tube inserted in an electrochemical cell with an argon cover gas. A tungsten electrode was used as a quasi-reference, and both a graphite basket and Ni basket were used to separately hold Ce0.8Gd0.2O2 and TiO2 powders. One open end of the YSZ tube was held at room temperature, while the other closed end was submerged in the molten salt at 650 °C. A platinum bearing paint coated the inside of the SOM and facilitated electrical contact from the nonconductive cold region to the conductive hot region. Argon gas was swept through the solid oxide membrane and an oxygen detector, where the oxygen pumped through the membrane during reduction was monitored. Initial oxygen evolution was measured using the oxygen meter and readings were observed to correlate to reduction of the Ce0.8Gd0.2O2 and TiO2 as determined from electrochemical data. The reduced Ce and Ti oxides were examined post experiment via SEM, EDS, and XRD. EDS and XRD were used to prove partial reduction in both the Ce0.8Gd0.2O2 and TiO2, but complete reduction to the metallic state was not observed for either oxide to date. EDS analysis found reduction of the TiO2 to as low as Ti­0.8O0.2 (with trace Cl). EDS analysis of the Ce0.8Gd0.2O2 found evidence of reduction to Ce0.8Gd0.2O (with trace Cl). XRD found evidence of LiTiO2, LiTi2O4, and (Li0.54Ti2.86)O6 from the TiO2 basket/electrode. Analysis of reduced products may have been impacted from air exposure during analysis. Operation of the cell for an extended period of time led to degradation of the solid oxide electrode. The data indicated that the process works as expected, but that further development of solid oxide membranes that are stable for oxide reduction are needed.
Microstructure and Compositional Defects Affects Proton Conductivity and Reactions in Y-doped BaZrO3 Thin Films
Authors: Yang Nan , Di Bartolomeo Elisabetta , Foglietti Vittorio , Cantoni Claudia , Belianinov Alex , Tebano Antonello , Licoccia Silvia , Lee Tien-Lin , Schlueter Christoph , Kalinin Sergei V. , Balestrino Giuseppe , Aruta Carmela 
Published: February 2020

Doped perovskite oxides have been widely studied in recent years as proton conducting solid electrolytes for different electrochemical devices, e.g. Solid Oxide Fuel Cells (SOFCs). By using the proton conductor as the electrolyte in a SOFC, the fuel dilution issue can be avoided due to the water formation at the cathode side instead of the anode. Among all the alkaline-earth cerates and zirconates, Y doped BaZrO3 (BZY) has been considered one of the most promising electrolyte for the SOFCs applications for its significant proton conductivity as well as chemical stability.[1] However, most reported fuel cell performance values for this material is much lower than oxide ion conducting ceramics such as YSZ owing to an unavoidable microstructure change, i.e. high grain boundary density and low degree of the crystallinity.
In order to correlate the microstructure with the conductivity, we prepared BZY thin films by Pulsed Laser Deposition and discussed the effect of the microstructure on the proton conductivity.
In this presentation I will show the conductivity behavior as a function of temperature and thickness by Electrochemical Impedance Spectroscopy (EIS).[2] I will focus on the interface between BZY and substrate NdGaO3 and show the cross-sectional electrochemical activity change with nanoscale resolution by Electrochemical Strain Microscopy (ESM). [3] I will highlight the interplay between the interface defects and the electrochemical performance by comparing the EIS, ESM results with Scanning Transmission Electron microscopy (STEM). I will further show the complementary study by bulk sensitive hard x-ray photoemission spectroscopy measurements which, together with Density Functional Theory calculations, demonstrate that Y and, to some extent, also Zr ions, substitute for Ba near the interface with the substrate.
[1] A. D’Epifanio, E. Fabbri, E. Di Bartolomeo, S. Licoccia, E. Traversa, Fuel Cells, 1,69-762008 (2008).
[2] V. Foglietti, Nan Yang, A. Tebano, C. Aruta, E. Di Bartolomeo, S. Licoccia, C. Cantoni, G. Balestrino, Applied Physics Letters 104 , 081612 (2014).
[3] Nan Yang, C. Cantoni, V. Foglietti, A. Tebano, A. Belianinov, E. Strelcov, S. Jesse, D. Di Castro, E. Di Bartolomeo, S. Licoccia, S. V. Kalinin, G. Balestrino and C. Aruta, Nano Letters, 10.1021/acs.nanolett.5b00698, (2015).
(Invited) Fundamental Aspects of Electrocatalysis at Work in Water Electrolysis
Authors: Gottesfeld Shimshon 
Published: February 2020

Abstract Text:
A general aspect of electrocatalysis described most recently in [1,2] , is the involvement of the electrode (over)potential in generation of catalytically active sites. It has been demonstrated that , in a wide variety of ORR processes taking place in low temperature fuel cells, the electrocatalytic process is "ignited" by a potential-driven change in steady state catalyst surface composition . The common involvement of such potential-driven, surface composition change in the mechanism of electrocatalytic processes , has led to the conclusion that fuel cell electrocatalytic processes , particularly the ORR, are, in general, "redox mediated" , including so at metal electrocatalysts such as Pt [1,2].
In this paper, the applicability of the same type mechanism to electrocatalytic processes in water electrolysis, particularly the OER, is elucidated. Much the same way as in the case of ORR at a variety of electrocatalyst surfaces, the OER also exhibits generally a dependence on overpotential of: 'low Tafel slope of 60 mV/decade ,or lower, at low currents, followed by higher Tafel slope of around 120mV/decade at higher currents '. This general pattern is fully expected for a mechanism involving potential activation of surface sites. Inclusion of the change of active site population with potential in the expression for the current potential dependence, results in potential-dependence of the pre-exponential factor, with the consequence of a low Tafel slope around the standard potential of the redox couple mediator [1,2].
Recently reported polarization curves for the OER ,to be discussed in this talk (3), exhibit the typical behavior described above. As commonly done, the interpretation was given in the form of change in RDS with overpotential. The insight proposed here, sugegsts that the RDS may very well remain the same throughout the relevant potential range and the observed change in Tafel slope is fully explained by change with overpoential in steady state, active surface site population.
Much the same way as in the case of fuel cell electrocatalysis [1,2], the important consequence of such general mechanism is that the effectiveness of the electrocatalyst depends on the magnitude of the overpotential required to activate the surface-redox-mediating system. Proximity of E0,surf.redox to E0,cell process should enable, in principle, high voltage efficiency of the electrolyzer.
(1) S. Gottesfeld, ECS Trans. 2014 61(31): 1-13
(2) S. Gottesfeld, ECS Trans. 2015 66(29): 13-30
(3) R.I. Doyle and E.G. Lyons. JECS, 160, H42, 2013
First Principles Studies of Electrocatalysis: From Methodology Development to Computational Design of Bi-Functional Catalysts with Improved Performance
Authors: Zeng Zhenhua , Greeley Jeff 
Published: February 2020

Over the past decade, tremendous advances have made on first principles based modeling of interfacial electrochemistry, which permit not only the mechanistic understanding of the basic thermodynamics and kinetics of complex electrocatalytic reaction networks and but also computational design of new alloy electrocatalysts. [1] Nevertheless, it is still a big challenge for the modeling of electrified interfaces with explicit double layer features (i.e. hydrogen bonds, solvent, electrode potential), which in some instances, yield completely unexpected physical and catalytic properties. For alkaline electrocatalysis at bi-functional three-phase boundaries of ultra-thin 3d transition metal (hydroxy)oxide films, Pt substrates, and the surrounding water,[2,3] it is more challenging, as the interface structures are largely unknown and the large errors in standard DFT calculations on the description of strongly-correlated (hydroxy)oxides. These have significantly impeded the design of new bi-functional catalysts with further improved performance.
In this talk, I will briefly review the methodologies we have recently developed, including a synergistic strategy towards highly accurate prediction of Pourbaix diagram of transition metal (hydroxy)oxides,[4] a simple scheme for fast screening of stable single layer transition metal (hydroxy)oxide film/metal interfaces under electrochemical conditions. Next, using hydrogen evolution reaction as an example, I will demonstrate how these techniques can be applied to understand the steady state, the active phases and the catalytic mechanism of mono- and bi-functional catalysts. Finally, I will show these understandings can be used to design new bi-functional catalysts with improved performances.
If time permit, I will introduce some of our recent developments on explicitly modeling of electrified electrode/electrode interfaces with full double layer features.
[1] J. Greeley, I. E. L. Stephens, A. S. Bondarenko, T. P. Johansson, H. A. Hansen, T. F. Jaramillo, J. Rossmeisl, I. Chorkendorff, J. K. Nørskov, Nat. Chem. 2009, 1, 552-556.
[2] Subbaraman, R.; Stamenkovic, V.; Markovic, N. et al, Science 2011, 334, 1256.
[3] Subbaraman, R.; Greeley, J.; Stamenkovic, V.; Markovic, N. et al, Nat Mater 2012, 11, 550
[4] Z. Zeng, M. K. Y. Chan, Z.-J. Zhao, J. Kubal, D. Fan, J. Greeley, J. Phys. Chem. C 2015, 119, 18177
Lateral Size Effect on Oxygen Evolution Reaction Activity of IrO2 Nanosheet
Authors: Takimoto Daisuke , Ayato Yusuke , Mochizuki Dai , Sugimoto Wataru 
Published: February 2020

Iridium dioxide (IrO2) is well known as an electrocatalyst with good activity for the oxygen evolution reaction (OER). We demonstrated earlier that IrO2 nanosheets, which are prepared via exfoliation of layered IrO2, exhibited similar performance to IrO2 nanoparticles (2-3 nm in diameter).1) In this study, we show that the OER activity of IrO2 nanosheet can be improved by down-sizing the lateral size of IrO2nanosheets.
IrO2 nanosheet was derived via exfoliation of layered H0.3Ir0.93O2×nH2O through a process reported previously. The lateral size of IrO2 nanosheet was reduced by ultrasonic treatment for 30 min with a homogenizer. The working electrode was prepared by dropping the IrO2 nanosheet on a glassy carbon electrode. A thin layer of Nafion ionomer was cast on the electrode. All electrochemical measurements were conducted in 0.1 M HClO4 (25oC).
The lateral size of as-prepared IrO2 nanosheet decreased from 258 nm to 111 nm by ultrasonic treatment. The electrochemically active surface area for both nanosheets was similar. The OER activity of IrO2 nanosheet with small lateral size was 881 A (g-IrO2)‒1, 1.9 times higher than that of as-prepared IrO2 nanosheet (451 A (g-IrO2)‒1). The edge sites of small lateral nanosheet size were 1.7 times higher than that of as-prepared nanosheets, corresponding well the enhancement in OER activity. The result suggests that the OER activity of IrO2nanosheet was enhanced by down-sizing the lateral size of nanosheet, which increased the amount of edge sites.
1) W. Shimizu, T. Ishida, S. Miyasaka, Y. Ayato, and W. Sugimoto, 227th ECS meeting, Chicago, IL (2015).
Cobalt Molybdenum Phosphide As a Non-Noble-Metal Catalyst for the Hydrogen Evolution Reaction
Authors: Chen Wei-Fu , Fang Si-Lin , Chen Kuei-Hsien , Chen Li-Chyong 
Published: February 2020

To replace Pt electrocatalysts for the HER in acidic electrolytes, several approaches have been exploited on transition metals through modifying the d–states at the Fermi level of the metal center by the alloying nonmetal elements such has sulfur, nitrogen and carbon.1 To further reduce the overpotential and enhance the stability, ternary compounds such as nickel molybdenum nitride2 have been shown enhanced performance in the HER. Very recently, metal phosphides, known as efficient hydrotreating catalysts, have also been demonstrated as HER catalysts, such as MoP,3 CoP,4 and Ni2P.5 Unlike bulk molybdenum dichalcogenides, which show poor activity, hexagonal molybdenum phosphide (MoP) exhibits good HER activity in bulk form, however, its performance is still limited by the intrinsic strong hydrogen binding energy.
In this study, attempts to synergize the electronic properties of cobalt phosphide and molybdenum phosphide by synthesizing ternary cobalt molybdenum diphosphide lead to the formation of an efficient electrocatalyst for the HER. X-ray diffraction data and high-resolution transmission electron microscopy show that this cobalt molybdenum phosphide crystallizes in space group P63/mmc and a formula of CoMoP2 (Figure 1). Incorporation of the sequentially stacked layers of CoP6 and MoP6 prisms on a single CoMoP2 structure brings about a significant enhancement in the HER kinetics and fast charge transfer. Characterization using X-ray absorption, electrochemical impedance analysis and electrochemical activity and Tafel behavior will be discussed.

References

1. W.-F. Chen, J. T. Muckerman and E. Fujita, Chem. Commun.
2013, 49, 8896-8909.
2. W.-F. Chen, K. Sasaki, C. Ma, A. I. Frenkel, N. Marinkovic, J. T. Muckerman, Y. Zhu, R. R. Adzic, Angew. Chem. Int. Ed.
2012, 51, 6131-6135.
3. X. Peng, M. Alam Sk, L. Thia, X. Ge, R. J. Lim, J.-Y. Wang, K. H. Lim and X. Wang, Energy Envirn. Sci.
2014, 7, 2624.
4. Q. Liu, J. Tian, W. Cui, P. Jiang, N. Cheng, A. M. Asiri and X. Sun, Angew. Chem. Int. Ed., 2014, 53, 6710.
5. E. J. Popczun, J. R. McKone, C. G. Read, A. J. Biacchi, A. M. Wiltrout†, N. S. Lewis and R. E. Schaak, J. Am. Chem. Soc., 2013, 135, 9267–9270.

Acknowledgement

This work was carried out at National Taiwan University, and financially supported by Ministry of Science and Technology (Taiwan) and Academia Sinica (Taiwan).

Figure 1
High-Performance Organic Redox Flow Batteries in Aqueous and Nonaqueous Electrolytes
Authors: Wei Xiaoliang , Xu Wu , Duan Wentao , Liu Tianbiao , Huang Jinhua , Vemuri Rama Sesha , Cosimbescu Lelia , Murugesan Vijayakumar , Brushett Fikile R. , Moore Jeffery S. , Liu Jun , Zhang Lu , Wang Wei , Sprenkle Vincent 
Published: February 2020

Redox flow battery is a promising large-scale grid energy storage technology. Its advantage of separating energy and power allows independent designs of tank volume and stack size and thus offers tremendous flexibility for different energy/power ratio applications. Traditional inorganic redox materials have suffered limited solubility, low electrochemical reactivity and/or high cost. Instead, organic compounds are being considerably pursued because of their molecular diversity, structural tailorability, environmental benignity, and potential low cost. A number of organic flow battery systems have been investigated.1-3

Here we report several organic redox flow chemistries in aqueous and nonaqueous electrolytes.4,5Promising redox material candidates have been identified with desirable redox potentials, high solubilities, and good electrochemical properties. Flow cells of these systems demonstrated remarkable cell efficiencies and high rate performance. Functional groups present in these molecules play an important role to tune solubility and chemical stability of redox species. Rational molecular engineering will be discussed as a general strategy to improve the battery performance and durability.

References

(1) W. Wang, Q. Luo, B. Li, X. Wei, L. Li, Z. G. Yang, Adv. Funct. Mater.
2013, 23, 970.
(2) K. Gong, Q. Fang, S. Gu, S. Li, Y. Yan, Energ. Environ. Sci.
2015, DOI: 10.1039/C5EE02341F.
(3) G. L. Soloveichik, Chem. Rev.
2015, DOI: 10.1021/cr500720t.
(4) X. Wei, W. Xu, J. Huang, L. Zhang, E. Walter, C. Lawrence, M. Vijayakumar, W. A. Henderson, T. Liu, L. Cosimbescu, B. Li, V. Sprenkle, W. Wang, Angew. Chem. Int. Ed.
2015, 54, 8684.
(5) T. Liu, X. Wei, Z. Nie, V. Sprenkle, W. Wang, Adv. Energy Mater.
2016, 6, DOI: 10.1002/aenm.201501449.

Figure 1. Flow cell cycling performance of: (a) nonaqueous N-methylphthalimide (anolyte)/di-t-butyl-dialkoxybenzene (catholyte) system; and (b) aqueous methyl viologen (anolyte)/HO-TEMPO (catholyte) system.5

Figure 1
Cerium-Hydrogen Redox Flow Cell Optimization
Authors: Tucker Michael C , Weiss Alexandra , Weber Adam Z 
Published: February 2020

The Ce/H2 redox flow cell is a promising system for large-scale energy storage due to its high open circuit potential (OCV) relative to other aqueous systems.[1] The system consists of an electrochemical cell which is fed reactants from storage tanks containing gaseous hydrogen (negative side) and an aqueous solution of Ce3+ and Ce4+ (positive side). During discharge, hydrogen is oxidized to protons at the negative electrode. The protons pass through an ion-conducting membrane and react with Cerium(IV) methanesulfonate at the positive electrode to produce Cerium(III) methanesulfonate and methanesulfonic acid (MSA). The electrochemical reactions are shown below with the forward direction corresponding to discharge and the reverse to charge.
Negative: 0.5H2(g) = H+(aq) + e- E0=0.00V (1)
Positive: Ce4+(aq) + e- = Ce3+(aq) E0=1.5-1.7V (2)
Overall: Ce4+(aq) + 0.5H2(g) = Ce3+(aq) + H+(aq) E0=1.5-1.7V (3)
Previous work by Hewa Dewage et. al established proof of concept for this device, demonstrating ~150mW/cm2 peak discharge power using platinized titanium mesh cerium electrode and commercial Pt-on-carbon paper hydrogen electrode.[1] In this work, we further optimize the cell materials, electrolyte composition, and operating protocol. It is found that Pt mesh type and surface area, membrane pretreatment, MSA concentration, and upper cutoff voltage have a large impact on performance. Optimizing these parameters results in power density exceeding 650 mW/cm2, as shown in Figure 1. Cell cycling efficiency is shown as a function of current density in Figure 2. Energy efficiency of 90% is achieved, although at low current density. Inefficiency is dominated by voltaic losses, which are thought to arise from kinetic and mass-transport limitations in the cerium electrode.
This paper will discuss the optimization effort in detail, as well as initial cycling stability results. Based on these results, we conclude that the cerium/hydrogen redox flow cell is indeed a good candidate for large-scale energy storage, due to high cell voltage, promising power density and energy efficiency, and reasonable cerium solubility. Future efforts should focus on developing improved cerium-electrode structures and catalysts, and determining durability of the cell.
References
[1] Hewa Dewage, H., B. Wu, A. Tsoi, V. Yufit. G. Offer, and N. Brandon, J. Mater. Chem. A (2015) 3, 9446-9450.

Figure 1