bluuebunny/crossref_metadata_2025_split huggingface dataset:
Galvanic Corrosion of Mild Steel Under Iron Sulfide Layers
Authors: Navabzadeh Esmaeely Saba , Nesic Srdjan 
Published: February 2020

Iron sulfide corrosion product layers have recently become the center of attention in H2S corrosion. The iron sulfides role on mild steel corrosion exposed to H2S containing environments has been reported to be related to their semi-conductive properties. The two most stable phases, pyrite and pyrrhotite have similar resistivity and a more positive open circuit potential (OCP) when compared to mild steel OCP. In an earlier study, the authors reported a comparable electroactivity to what was measured on an X65 mild steel surface. Given conditions for establishing a galvanic cell are present in a conductive electrolyte, a corrosion product layer containing sulfide phases could enhance the rate of cathodic reactions by providing a larger cathodic surface area. Also, the mixed potential established between these layers with the mild steel is often more positive than the OCP for the uncoupled steel. This results in an intensified iron dissolution rate. In conditions where the steel is locally exposed to the corrosive media, this leads to localized corrosion.
The evidence for a galvanic effect related to iron sulfides coupling to mild steel has been mostly circumstantial. The galvanic corrosion that was attributed to such conditions was a conclusion that was reached through deductive reasoning, without direct proof. In the current study, zero resistance ammeter (ZRA) measurements were utilized to measure the magnitude of the galvanic current between coupled X65-pyrite and X65-pyrrhotite electrodes. Pyrite and pyrrhotite electrodes were prepared using geological specimens. The experiments were conducted in a deaerated conductive aqueous solutions at different pH at room temperature with iron sulfide surface area being seven times higher than the X65 steel surface area.
The experimental results for the same cathode to anode ratio showed that a higher galvanic current was measured at the X65-pyrrhotite couple versus X65-pyrite surfaces. It is noteworthy that upon exposure to an aqueous solutions containing H+, pyrrhotite undergoes a surface reduction to troilite and produces H2S. In a more acidic environments the produced H2S does not have a substantial effect on the corrosion currents. However, in aqueous solutions with limited available H+, the produced H2S plays a significant role in enhancing the corrosion currents.
It was shown in a prior publication that at pH 5.0 the currents at the pyrrhotite surface was higher than what was measured at the pyrite or X65 surfaces. This resulted in a much higher galvanic current at the X65-pyrrhotite surface.

Figure 1
Controlled Superlattice Assembly – a Step Towards Superlattice Devices
Authors: Yu Yixuan , Yu Dian , Orme Christine A. 
Published: February 2020

Ordered assemblies of nanocrystals called superlattices are promising materials for next generation devices. detectors and sensors. However, traditional methods to assemble nanocrystals lack the control needed for device integration. To fill this gap we show that electrophoretic deposition can be used to drive nanocrystal assembly. We will demonstrate that field-driven assembly can deposit well-ordered superlattices with diffraction peaks out to (2,2,8) over large (cm2) areas. Moreover, the process is amenable to wafer-level deposition, reversible and several orders of magnitude faster than conventional solvent evaporation or co-solvent techniques. The electric field controls the nanocrystal flux making the deposition process akin to vapor deposition. To demonstrate this new level of control, we use the field to systematically change the growth rates and nucleation density. These are confirmed using in situ quartz crystal microbalance to measure growth rates and ex situ imaging to measure nucleation density. We use nickel and silver nanocrystals to illustrate that films can grow either via a layer-by-layer or by an island formation mechanism and that ligands play a central role in determining whether nanocrystals assemble into thin films or colloidal crystals. This new level of control allows us to tune the correlation length, which we expect to have advantages for fundamental studies and to benefit device performance.
Work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Electrochemical Synthesis of H2O2 Via Water Electrolysis
Authors: Siahrostami Samira , Shi Xinjian , Abroshan Hadi , Zheng Xiaolin , Nørskov Jens 
Published: February 2020

Hydrogen peroxide (H2O2) is a crucial chemical with a wide range of applications in various industries, including paper bleaching, textile manufacturing and environmental protection for distillation, detoxification and color removal of wastewater. Electrochemical production of hydrogen peroxide (H2O2) offers small scale decentralized process which is highly desirable for remote usages. Both oxygen reduction (eq. 1) and water oxidation (eq. 2) reactions could be exploited to produce H2O2.
O2 + 2(H++e-) ---> H2O2 E0 = 0.7 V (1)
2H2O ---> 2(H++e-) + H2O2 E0 = 1.76 V (2)
These reactions are simple and remarkable, but in practice selectivity toward the desired H2O2 product is an issue since these are not the thermodynamically favored reactions for oxygen reduction and water oxidation. Over the past years, several efforts have been made to find selective, and active catalysts for these reactions.1–4 In this work, by combining density functional theory (DFT) calculations and experiment, we provide leads to design suitable electrocatalysts with high selectivity and activity for H2O2 synthesis from both processes.3

References

(1) Siahrostami, S.; Verdaguer-Casadevall, A.; Karamad, M.; Deiana, D.; Malacrida, P.; Wickman, B.; Escudero-Escribano, M.; Paoli, E. a; Frydendal, R.; Hansen, T. W.; Chorkendorff, I.; Stephens, I. E. L. S.; Stephens, I. E.; Rossmeisl, J. Nat. Mater.
2013, 12 (12), 1137–1143.
(2) Verdaguer-Casadevall, A.; Deiana, D.; Karamad, M.; Siahrostami, S.; Malacrida, P.; Hansen, T. W.; Rossmeisl, J.; Chorkendorff, I.; Stephens, I. E. L. Nano Lett.
2014, 14 (3), 1603–1608.
(3) Siahrostami, S.; Li, G.-L.; Viswanathan, V.; Nørskov, J. K. J. Phys. Chem. Lett.
2017, 1157–1160.
(4) Shi, X.; Siahrostami, S.; Li, G.-L.; Zhang, Y.; Chakthranont, P.; Studt, F.; Jaramillo, T. F.; Zheng, X.; Nørskov, J. K. Nat. Commun.
2017 (SEPT), 1–12.
N/S-Me (Fe, Ni) Doped Porous Carbon Derived from Metal–Organic Frameworks As Efficient Electrocatalysts for Oxygen Reduction Reactions
Authors: Dong Fang , Tang Qiaowei , Liu Junyu , Liu Cong , Qiao Jinli 
Published: February 2020

In the past few decades, polymer electrolyte membrane fuel cells (PEMFCs), as a kind of clean, efficient energy sources, which is considered to be the most promising solution to solve the increasingly serious energy crisis and reduce the environmental pollution, have experienced continuously increasing attention1. Oxygen reduction reaction (ORR) in fuel cells plays a decisive role in determination of performance, and electrocatalysts with high-performance ORR are essential for practical applications. However, the commercialization of PEMFCs has long been hindered by the utilized expensive Pt-based catalyst for cathodic ORR2 3. To solve the bottleneck, non-platinum-group-metal electrocatalysts with low cost, high activity and durability have been intensively pursued as alternatives to Pt for the ORR4. Recent years witnessed the dramatic interest in using nitrogen/sulfer-doped porous carbon as one of the promising ORR catalysts. Herein, we present N/S-Me (Fe, Ni) doped porous carbon derived from a metal–organic frameworks MOF-67 (ZIF-N/S-Me-PC) as highly efficient ORR electrocatalysts. The catalytic ORR activities of ZIF-N/S-Me-PC are studied by linear sweep voltammetry (LSV), employing rotating disk electrode (RDE) and rotating ring-disk electrode (RRDE) techniques to quantitatively obtain the ORR kinetic constants and the catalysts' possible reaction mechanisms. In comparison to the commercial Pt/C (20%), the electrocatalyst ZIF-N/S-Me-PC exhibits a pronounced positive shift in Eonset. In addition, it also demonstrates excellent long-term stability and durability during the 5000-cycle continuing-oxygen-supply (COS) accelerating durability tests (ADTs). Catalytic ORR activities were thoroughly examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), low-temperature N2 adsorption and X-ray photoelectron spectroscopy (XPS).
References
1 M.J. Wu, E.G. Zhang, Q.P. Guo, Y.Z. Wang, J.L. Qiao, K.X. Li, P.C. Pei, Appl. Energy, 175, 468 (2016).
2 Q.W. Tang, L.M. Wang, M.J. Wu, N.N. Xu, L. Jiang, J.L. Qiao, J. Power Sources, 365, 348 (2017).
3 M. Sahoo, S. Ramaprabhu, Energy, 119, 1075 (2017).
4 M.J. Wu, Q.W. Tang, F. Dong, Z.Y. Bai, L. Zhang, J.L. Qiao, J. Catal, 352 , 208 (2017).
(Invited) Membranes with Recombination Catalyst for Hydrogen Crossover Reduction: Water Electrolysis
Authors: Bessarabov Dmitri 
Published: February 2020

Hydrogen and oxygen crossover phenomena through a solid polyelectrolyte membrane constitute one of the important safety concerns in PEM electrolysis.
Hydrogen gas crossover in PFSA membranes during water electrolysis is a dynamic variable, characterised by complex functional relationships between the membrane water content, nature of the membrane, and operational conditions.
Mitigation strategies to reduce gas crossover may include various approaches, based on the mechanism of interaction of hydrogen and the membrane matrix. These approaches may include passive solutions, reactive solutions, and combinations thereof. The most straightforward solution to reduce crossover is to increase membrane thickness; however, this leads to higher resistance to proton transport. Another rather straightforward approach includes developing mixed-matrix membranes, by adding fillers into the membrane matrix. By selecting a membrane material with a low diffusion coefficient and low water content, one can also reduce gas crossover. It is known that sulfonated hydrocarbon PEMs have significantly lower gas permeability than PSFA membranes (Bessarabov and Millet, 2018).
The reactive approach includes promoting the process of hydrogen consumption by introducing Pt into either the CL and/or the current collector. The first membranes with Pt were fabricated for the purpose of self-humidification, for fuel cell applications (Watanabe et al., 1998). According to Ito et al. (2016) and Abdalla et al. (2017), it is critical for safe PEM electrolysis. The very well understood mechanism of hydrogen consumption involves recombination of hydrogen and oxygen on a Pt catalyst.
This paper will describe morphology of Pt catalyst that was developed for the recombination purposes and embedded in the PFSA membranes. Experimental data for hydrogen reduction permeation will be presented. Catalyst was characterized by HR TEM.
References.
Abdalla, S., Al-Marzouki, F., Obaid, A., 2017. Safety considerations during production and consumption of hydrogen using proton exchange membrane electrolysis. J. Renew. Sustain. Energy 9, 013101
Bessarbov, D. and Millet, P. PEM Water Electrolysis, Elsevier, 2018 (in press)
Ito, H., Miyazaki, N., Ishida, M., Nakano, A., 2016. Cross-permeation and consumption of hydrogen during proton exchange membrane electrolysis. Int. J. Hydrogen Energy, 41 (45), 20439–20446
Watanabe, M., Uchida, H., Emori, M., 1998. Analyses of self-humidification and suppression of gas crossover in Pt-dispersed polymer electrolyte membranes for fuel cells. J. Electrochem. Soc. 145 (4), 1137–1141
(Invited) Pyrochlore-Type, Acid-Stable Electrocatalysts for Oxygen Evolution Reaction
Authors: Yang Hong 
Published: February 2020

Multiple important electrochemical processes including hydrogen generation from water reply on acid-stable electrocatalysts for oxygen evolution reaction (OER). The material choice of OER electrocatalysts in acid is often limited to only two major types of oxides (e.g., RuO2 and IrO2). Recently, ternary compounds have been reported to have excellent OER performance. Among them, our group developed pyrochlore-type electrocatalysts of various compositions. Yttrium ruthenate (Y2Ru2O7-δ) was shown to have significantly enhanced performance towards OER in acid media over both RuO2 and IrO2 catalysts at current density about 1 mA/cm2 [1]. It has an onset overpotential of 190 mV in 0.1-M perchloric acid solution. Tafel plots show the Y2Ru2O7-δ catalyst had enhanced activity from 55 mV/dec for the first cycle to 46 mV/dec for the 10,000th cycle. In comparison, the OER performance for RuO2 catalyst degraded from 61 mV/dec for the first cycle to 72 mV/dec for the 10,000th cycle under the same testing conditions. A range of techniques including X-ray absorption spectroscopy (XAS) and computational tools such as density functional theory (DFT) calculation have been used to understand the structural origins of enhanced performance. Our preliminary data suggest a low valence state in yttrium ruthenate (Y2Ru2O7-δ) favors the high OER activity, while lowered band center energy for the overlap between Ru 4d and O 2p orbitals contributes to the stability. A systematic study on the structural origin for high OER performance has further been carried out using a series of A2Ru2O7-δ pyrochlore-type electrocatalysts and will be presented in this talk. Strategies for improving the overall performance of these OER catalysts will also be discussed [2,3].
References:

M. Kim,# P.-C. Shih,# K.-C. Tsao, Y.-T. Pan, X. Yin, C.-J. Sun, H. Yang, J. Am. Chem. Soc., 2017, 139, 12076-12083 (#: equal contribution).

M. Kim, X. X. Chen, Y.-T. Pan, P.-C. Shih, H. Yang, J. Electrochem. Soc., 2017, 164, F1074-F1080.

M. Kim, X. X. Chen, P.-C. Shih, H. Yang, ACS Sustainable Chem. Eng., 2017, 5, 10190-10917.
High-Performance Lithium–Sulfur Batteries Based on Layered Double Hydroxides–Carbon Nanotubes Composite Cathode and a Dual-Coated Graphene–Polypropylene–Al2O3 Separator
Authors: Hwang Jang-Yeon , Sun Yang-Kook 
Published: February 2020

Li–S batteries are becoming attractive due to their tremendous merits. In Li–S batteries, the sulfur (S8) undergoes a two-electron redox reaction with Li, which can provide a high theoretical capacity of 1675 mA h g−1 and can achieve high energy densities (2600 Wh kg−1) that are three-fold higher than those of transition metal oxide cathodes.1,2 Although Li–S battery technology has made great progress due to such intensive research efforts,3-5 effective approach for high performance Li–S battery to deliver a high capacity and good capacity retention with high sulfur loading has not been suggested yet.
Herein, a novel lithium–sulfur cell design is proposed, which consists of sulfur and magnesium–aluminum-layered double hydroxides (MgAl-LDH)–carbon nanotubes (CNTs) composite cathode with a modified polymer separator produced by dual side coating approaches (one side: graphene and the other side: aluminum oxides). The composite cathode functions as a combined electrocatalyst and polysulfide scavenger, greatly improving the reaction kinetics and stabilizing the Coulombic efficiency upon cycling. The modified separator enhances further Li+-ion or electron transport and prevents undesirable contact between the cathode and dendritic lithium on the anode. The proposed lithium–sulfur cell fabricated with the as-prepared composite cathode and modified separator exhibits a high initial discharge capacity of 1375 mA h g−
1 at 0.1 C rate, excellent cycling stability during 200 cycles at 1 C rate, and superior rate capability up to 5 C rate, even with high sulfur loading of 4.0 mg cm−
2. In addition, the findings that found in postmortem characterization of cathode, separator, and Li metal anode from cycled cell help in identifying the reason for its subsequent degradation upon cycling in Li–S cells.
Carbon Nanofibers (CNFs) Coated Ni Foam As 3D Integrated Current Collector and Sulfur Host in Li-S Batteries
Authors: Zeng Zhipeng , Liu Xingbo 
Published: February 2020

Tremendous attention has been paid to the energy conversion and storage devices for their rapidly growing market and more requirement for nowadays’ applications, ranging from portable electronics, electric tools to large renewable energy systems. The high theoretical capacity (1672 mAh g-1) and energy density (2600 Wh kg-1) for sulfur electrode make it be a very promising candidate for electric and hybrid electric vehicles among the various candidates. However, the commercialized process for this promising material is still greatly hindered by a series of issues, including the insulating of sulfur, large volume change, and the “shuttle effect” of polysulfides.
With this in mind, we developed the CNFs coated Ni foam both as the sulfur host and the current collector. The Ni foam was coated with two types of carbon layers. The inner one is relatively compact carbon layer rich in micropores, and the outer one is carbon nanofiber layer. After heat treatment at elevated temperature, sulfur was either physically impregnated into the micropores or chemically bond to C and Ni atoms. The surface and cross-section morphology were characterized by SEM and TEM and the chemical bond states were analyzed by XPS. The 3D conductive network, micropores, and chemical binding synthetically resulted in the high stability and excellent rate capability of the electrode, showing the potential application in developing high-performance Li-S batteries.
Synthesis and Electrochemical Properties of Nb2O5-Ge/GeO2 Core-Shell Structure for Reversible Lithium Storage
Authors: Kim Kyungbae , Kim Jae-Hun 
Published: February 2020

Group IV element-based nanostructures have been actively investigated as high-capacity anodes for Li-ion batteries. Among them, germanium (Ge)-based materials become newly promising because it shows a high theoretical capacity (ca. 1600 mAh·g-1) and faster Li transport properties compared to the other materials in the same group. However, the long-term cycling stability is still a challenging issue, which is resulted from volume expansion during cycling. To overcome the limitation, the way to maintain stable structures against the volume changes of Ge should be considered.
This study proposes a new Ge-based structure by incorporating Nb2O5, which is stable during Li insertion and extraction processes. An Nb2O5 nanoparticle core-Ge/GeO2 shell structure material was prepared by a simple hydrothermal method and the following heat-treatment. First, a microscale NbOx-GeOx precursor was synthesized by the hydrothermal process with copolymer producing core-shell structure. Subsequently, it was heat-treated to obtain pyrolysis of copolymer and to form a reduced Ge/GeO2 thin shell on the nanoscale Nb2O5 core structure without additional carbon sources. Electrochemical test results exhibited that the synthesized electrode materials had a high reversible capacity of 700 mAh·g-1 after 100 cycles with an initial coulombic efficiency of 74%. In the long-term cycling test with a high rate, it exhibited an excellent cycling stability with a capacity retention ratio of 97% even after 1000 cycles.
(Invited) Stability and Kinetics of the Li/Solid-State Electrolyte Interface
Authors: Sakamoto Jeff , Sharafi Asma , Wolfenstine Jeff , Taylor Nathan J , Wang Mike , Siegel Donald J , Dasgupta Neil P. 
Published: February 2020

While there have been recent advances in solid ion conductors exhibiting conductivities comparable to liquid electrolytes, how to best capitalize on these materials discoveries to enable new energy storage technology is currently not known. Of particular interest is the integration solid-state electrolyte into solid-state batteries; however, numerous questions remain. What are the design rules? How are solid-solid interfaces formed? How does charge transfer occur at interfaces?
Essentially, there are two interfaces of interest in solid-state batteries, distinguished by the electrode type; the alkali metal electrode and the ceramic electrode. Several key scientific challenges related to these two interfaces must be addressed to mature solid-state batteries. This discussion is centered on the alkali metal/solid electrolyte interface. The solid electrolyte based on garnet-type oxide, of nominal composition Li7La3Zr2O12 (LLZO), is used as a model system that simultaneously exhibits fast-ion conductivity and stability against metallic Li.
To date, there are few examples of bulk-scale Li-ion conducting solid electrolytes that are stable at the Li/Li+ redox potential. This paper elucidates stability and kinetics as a function of LLZO composition and surface chemistry. EIS, TEM, and electron spin resonance analysis describes the subtle interaction at the interface between Li metal and LLZO. Simple approaches to achieving negligible Li-LLZO interface resistance (~1 Ohm.cm-2) with no coatings is described. Based on this mechanism, a simple procedure for removing these surface layers is demonstrated, resulting in a dramatic increase in Li wetting and the elimination of nearly all interfacial resistance. Combined, the demonstrated stability and low interfacial resistance suggests a pathway to achieving viable high energy density solid-state batteries enabled by the LLZO-based solid electrolyte.
Controlled Surface Structure and Chemistry with Transition Metal Enrichment for Cathode Materials
Authors: Ahn Juhyeon , OH Si Hyoung , Chung Kyung Yoon , Cho Byung Won 
Published: February 2020

Transition metals enrichment on the surface of layered nickel-cobalt-manganese oxide cathodes leads to the structural changes, hindering the facile lithium-ion transportation at the surface of the particles. These inhomogeneous metal distributions and structural evolutions are progressively proceeded with electrochemical cycling from the surface to the bulk, which causes to severe material degradation and short cycle life. In this study, we develop the new surface structure and chemistry on the layered cathode materials to enhance the battery performances by controlling the local concentration of transition metal. Our strategy is to improve the surface instabilities by either suppressing unwanted transition metal segregation or creating an ion conductive oxide phase or both on the specific crystallographic planes for the layered host materials. This is conducted by adding electrochemically inactive transition metals together with the active metals during the synthesis because that the transition metal elements are individually and preferentially enriched to the particular facets such as (20–2), (200), and (001) of the layered bulk. As a result, the unique surface layers are spontaneously formed along the surface planes within a few nanometer. The electrochemical characteristics shows that the newly created surface phases strongly influence on the high rate performance and long cycle life.
This work is supported by the National Research Foundation of Korea (NRF-2011-C1AAA001-0030538).