bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the Reaction Mechanism of Sodium Insertion/Extraction in SnF2 Anode Material
Authors: Ali Ghulam , Chung Kyung Yoon 
Published: February 2020

Sodium-ion batteries (SIBs) are considered as a potential candidate for electrical energy storage system (ESS) because of their advantages such as low-cost system and evenly distributed sodium resources worldwide. However, there is need to explore new electrode materials for the realization of SIBs. Particularly, the anode side of SIBs needs more improvements as commonly investigated anodes in lithium-ion batteries (LIBs) such as graphite and silicon do not intercalate sodium ions.
In the search for high capacity anodes for SIBs, we have investigated electrochemical properties of a nanocomposite based on SnF2 and acetylene black. The nanocomposite electrode delivers a reversible capacity of 563 mAh g-1 which is higher than the specific capacity of 323 mAh g-1 of the micron-sized bare SnF2 electrode. The sodium insertion/extraction process of the high-performing nanocomposite is revealed by in-situ XRD, ex-situ XAS and TEM techniques. The reaction mechanism revealed using in-situ XRD show the existence of a solid solution of two or more compositions during cycling. Ex-situ XAS reveals the electronic and atomic configurations of SnF2 at different potential states during dis/charging. The XAS results reveal that the valence change of Sn follows the conversion (SnF2 + 2Na → Sn + 2NaF) and the alloying (Sn + XNa → SnNaX) reaction upon sodium insertion into a composite.
Fuel Cell Performance and Durability of Intermetallic Oxygen Reduction Catalysts
Authors: Pan Yung-Tin , Kim Yu Seung , Li Junrui , Sun Shouheng , Spendelow Jacob S 
Published: February 2020

Platinum-based alloy catalysts for the oxygen reduction reaction (ORR) continue to be the industry standard for fuel cell applications, but improvements are needed to increase ORR activity and durability. Despite extensive study, the effects of structure and composition on real world performance and durability in fuel cells are poorly understood. Most research to date has examined random alloy structures, but preliminary results from intermetallic catalysts, especially intermetallic tetragonal structured catalysts, have indicated that superior performance and durability can be achieved through creation of ordered intermetallic structures. Results so far indicate that the degree of ordering is a critical parameter in determining intermetallic catalyst activity and durability, with fully-ordered face-centered tetragonal (fct) FePt catalysts exhibiting substantially improved activity and durability compared to partially ordered phases [1].
Most work on intermetallic nanocatalysts reported so far has been based on ex situ testing methods that use an idealized aqueous electrochemistry environment. While these ex situ methods are inexpensive and convenient, they do not reliably predict performance and durability in real fuel cells. Therefore, rigorous catalyst testing in fuel cells is needed to build understanding of the relationship between catalyst properties and fuel cell performance and durability.
In our earlier work, we observed the instability of the intermetallic surface accompanied by substantial iron and performance loss after subjecting to the DOE catalyst AST (30,000 trapezoidal cycles between 0.6 and 0.95 V with 0.5 s rise time) in operating fuel cells. However, when the surface was chemically modified towards a Pt rich surface on the fct core, the stability was significantly improved (Figure 1). Initial results depicted indicate that Pt-on-fct-FePt can have performance comparable or even better than a baseline commercial Pt/C, despite the use of larger particles (5-7 nm for fct-FePt/C vs. 2-3 nm for Pt/C). Notably, the Pt-on-fct-FePt exhibits lower loss of performance following the 30,000 cycle AST. Ongoing work seeks to focus on optimizing the surface structure of fct-FePt and fct-CoPt intermetallic nanoparticle catalysts such that a synergistic effect between the surface and core can be established, i.e., a stable Pt surface that protects the fct-core that is thin enough to benefit from the geometric and electronic effects from the core.
Fig. 1. Fuel cell polarization behavior of Pt/C and fct-FePt/C before and after the 30,000 cycle AST. H2/air, 80°C, 100% RH, 150 kPaabs, 0.1 mgPt/cm2.
References

Q. Li et al., "New Approach to Fully Ordered fct-FePt Nanoparticles for Much Enhanced Electrocatalysis in Acid," Nano Lett. 2015, 15, 2468−2473.

Acknowledgements
This research is sponsored by the Fuel Cell Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy.

Figure 1
Development of Best Practices and Standard Protocols in Benchmarking Photoelectrochemical (PEC) Hydrogen Production
Authors: Xiang Chengxiang("CX") 
Published: February 2020

Photoelectrochemical (PEC) Hydrogen Production has advanced significantly in recent years, in particular, PEC devices with solar-to-hydrogen (STH) conversion efficiency that exceeded 10% were demonstrated in a range of configurations at the laboratory scale. To further advance this technology and reach the bench scale (0.1 kg/day) and sub-scale (2 kg/day) operational platforms, development of comprehensive Best Practices in screening, characterization and benchmarking at materials level, component level, device level and system level is critical.
In this presentation, I will talk about recent community-based efforts in defining targets, best practices and gaps in PEC hydrogen production in HydroGEN Energy Material Network (EMN) consortium. Specific challenges related to PEC will be discussed including scale up challenges, integration challenges at component level, lack of performance data and test protocols for photoelectrodes under real-world operating conditions and lack of fundamental understanding of photoelectrode corrosion mechanisms and accelerated test protocols. In addition, a briefly summary and status reports on lab EMN nodes/capabilities for PEC water-splitting will be addressed. Cross-cutting interactions with other advanced water-splitting technologies, including low/high temperature electrolysis and solar thermochemical water splitting, will also be discussed.
PbI2 Thin-Films for Photoelectrochemical Hydrogen Evolution
Authors: Fermin David , Tiwari Devendra 
Published: February 2020

PbI2 has become a highly prominent material in the field of photovoltaics as the key precursor in the fabrication of organo-halide perovskites films [1]. Despite intensive research in this area, the role of unconverted PbI2 in perovskite cells remains controversial. In fact, very little is known about the behaviour of PbI2 as a photocathode. In this contribution, we examine the photoelectrochemical properties of high quality PbI2 thin films obtained by gas phase anion replacement [2].
The preparation of PbI2 films is initiated by growing a thin PbS film on F:SnO2 electrodes, followed by spontaneous gas phase iodination at 200 ˚C. The structure and optical properties of the thin films were investigated by XRD, SEM, Raman Spectroscopy, diffuse reflectance and room temperature photoluminescence. The structural and spectroscopic information, supported by DFT calculations (PBESOL functionals), demonstrated the formation of the 2H- phase of PbI2 with a high degree of purity and a band gap of 2.4 eV. Electrochemical impedance spectroscopy in KI containing solutions showed a clear p-type behaviour with a flat band potential located 0.175 V vs Ag/AgCl and an effective majority carrier density of 1.6×1015 cm-3.
Photoelectrochemical studies in Ar-saturated KI solutions were characterized by a nearly ideal semiconductor-electrolyte junction at low illumination levels. Incident-photon-to-current efficiency exhibits values close to 50%, which can be quantitatively rationalized in terms of reflection losses, the width of the space charge region and a minority carrier diffusion length of 80 nm. The remarkable feature of this photocathode is the absence of surface recombination even at potentials close to the flat band value. The efficient hydrogen photogeneration is achieved at neutral pH and in the absence of co-catalysts. We shall briefly discuss the origin of the nearly ideal semiconductor-electrolyte junction behaviour and potential routes for stabilising the PbI2 surface for solar fuel applications.
References

Yang and J. You, Nature 544 (2017) 155

Tiwari and D.J. Fermin, Electrochim. Acta 254 (2017) 223
Colloidal Ternary Ni1-xCoxSe Alloy Nanocrystals with tunable compositions: Synthesis, Characterization and Electrocatalytic properties for the Oxygen Evolution Reaction
Authors: Manna Liberato , Wang Mengjiao , Shinde Dipak , De Trizio Luca 
Published: February 2020

Oxygen evolution reaction(OER) is one of the two half-reactions in water splitting. Sustainable OER is an essential prerequisite in hydrogen production from water. In the past few years, many research efforts have been directed towards the development of electrocatalysts for OER, which are based on noble metals and transition metal oxides. But these materials suffer from poor conductivity. Recently, it has been found that, transition metal chalcogenide materials, especially Ni- and Co- based compounds, can catalyze OER efficiently. However, the research on these systems is at the very beginning, and few syntheses of Ni1-xCoxSe nanocrystals (NCs) have been reported in the literature till now. Herein, we report a simple colloidal synthesis approach to grow ternary Ni1-xCoxSe NCs with tunable composition and study their OER properties. The phase of the nanocrystals is hexagonal irrespective of their composition. The composition of Ni and Co in the NCs can be easily controlled by tuning the experimental parameters. By performing OER on samples with different Ni/Co ratio, we optimized the composition for obtaining high performance OER. The best performing samples exhibit a catalytic OER current of 10 mA/cm2 at a small overpotential of 1.5 V vs. RHE with extended long-term stability. The detailed results will be presented in the meeting.
Figure. (a) TEM image of Ni0.37Co0.74Se and (b) Polarization curves of OER for NCs with different Ni/Co ratios

Figure 1
Multi-Modal Catalytic Cascades on Carbonaceous Scaffolds
Authors: Chavez Madelaine Seow , Monclova Jose , Hickey David P , Abdellaoui Sofiene , Gonzales Ivana , Minteer Shelley , Atanassov Plamen 
Published: February 2020

Fundamental understanding of the ways organic and/or inorganic catalysts can be incorporated with enzymes to enhance the efficiency of multi-step reactions can lead to knowledge that is crucial for any further improvements in the development of multi-component multi-step catalytic cascades. This knowledge can provide essential clues to the novel design of systems for energy conversion and harvesting as well as for production of advanced materials that require multi-step catalysis. The goal of this project is to develop strategies for spatially organizing three different catalysts (biological, molecular, and inorganic) using 3D-Graphene nanosheets (3D-GNS) as a scaffold and apply it to efficiently catalyze model catalytic cascade: multi-step oxidation of glycerol [1,2].
In this work, we first studied the immobilization of oxalate decarboxylase (OxDC) from Bacillus subtilis, through physical absorption and tethering using 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBSE) on conductive carbonaceous supports such as multi-walled carbon nanotube buckypaper and 3D-GNS. An indirect enzymatic assay using NAD-dependent formate dehydrogenase was performed to determine the kinetic parameters (K
M
V
M) of immobilized OxDC onto these supports. We also employed cyclic voltammetry to study the immobilization of a molecular catalyst, pyrene-tethered TEMPO derivative (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) on 3D-GNS. Furthermore, we explored optimal strategies to incorporate both OxDC and molecular catalysts in a way that will enable an efficient two-step catalytic cascade - the last two steps in the glycerol oxidation mechanism (Figure). Results of electrochemical studies show that OxDC and pyrene-TEMPO were successfully immobilized on the carbonaceous scaffold. Moreover, it was shown that this hybrid catalyst can catalyze two different reactions sequentially (i.e. conversion of oxalate to formate by OxDC/3D-GNS and oxidation of formate to CO2 by pyrene-TEMPO/3D-GNS).
[1] S. Abdellaoui, D. P. Hickey, A. R. Stephens, and S. D. Minteer, Recombinant oxalate decarboxylase: enhancement of a hybrid catalytic cascade for the complete electro-oxidation of glycerol. Chem. Commun., 51, 14330-14333 (2015).
[2] S. Abdellaoui, M. S. Chavez, I. Matanovic, A. R. Stephens, P. Atanassov, S. D. Minteer, Hybrid molecular/enzymatic catalytic cascade for complete electro-oxidation of glycerol using a promiscuous NAD-dependent formate dehydrogenase from Candida boidinii. Chem. Commun., 53, 5368-5371 (2016).

Figure 1
Influence of the Supporting Electrolyte on the Structure-Transport Properties of PFSA Membranes for Redox Flow Batteries
Authors: Kushner Douglas I. , Kusoglu Ahmet , Weber Adam Z. 
Published: February 2020

Redox flow batteries (RFBs) are poised at becoming one of the most promising technologies that are being explored for grid-scale energy storage from discontinuous power sources such as wind and solar.[1] This has resulted in a need for continued development and understanding of new redox couples and their supporting electrolyte counterparts, as well as improving membranes for RFB operation while reducing cost. Membranes employed in RFB technology are largely comprised of the perfluorosulfonic acid (PFSA) family (e.g. Nafion, Aquivion, and 3M PFSA) which exhibit different material properties depending on the surrounding environment, such as transport properties.[2] The structure-property relationships of PFSAs are well-known and studied,[3] providing the initial framework for our understanding; however, much of this work has been performed in either vapor or liquid water. Thus, it is of interest to elucidate how the structure and transport properties of PFSAs change in various electrolytes used in RFBs.
In this work, we discuss our progress in linking the electrolyte concentration-dependent nanostructure to the transport of ions in PFSA membranes. Sulfuric acid and hydrochloric acid represent the majority of supporting electrolytes used in RFB applications and are therefore the primary focus of this study. The polymer’s nanostructure in electrolytes is analyzed using small angle X-ray scattering (SAXS) in-situ, in order to understand the influence of the type and concentration of the supporting electrolytes on the characteristic morphological features of the membrane. Then, nanostructural information is linked to the ion transport through the membrane, via conductivity. Linking the conductivity and polymer morphology provides a better understanding of the structure-transport relationships of PFSAs in electrolytes, and their implications for membrane performance in a RFB cell.

Perry, M.L. and A.Z. Weber, Advanced Redox-Flow Batteries: A Perspective. Journal of the Electrochemical Society, 2016. 163(1): p. A5064-A5067.

Tang, Z., et al., Composition and Conductivity of Membranes Equilibrated with Solutions of Sulfuric Acid and Vanadyl Sulfate. Journal of the Electrochemical Society, 2013. 160(9): p. F1040-F1047.

Kusoglu, A. and A.Z. Weber, New Insights into Perfluorinated Sulfonic-Acid Ionomers. Chem Rev, 2017. 117(3): p. 987-1104.
Long-Term Atmospheric Corrosion of Hot-Dip Galvanized Steel and Zn-Al Coated Steel
Authors: Thierry Dominique , Persson Dan 
Published: February 2020

Hot dip galvanized steel and zinc alloyed coated steel such as ZnAl are widely used in the building industry. However, despite large efforts made to study the corrosion products formed on zinc under atmospheric weathering conditions (see for instance reference 1 and 2), very few data exist on HDG and zinc alloyed coated steel [5].
This work is a part of a larger research program were steel with different zinc coatings are exposed on a worldwide basis on well characterized exposure sites in Europe, Asia and North America, see Table 1.
Corrosion rates of hot dip galvanized steel and zinc aluminum coated steel (e.g. Zn5%Al and Zn 55% Al) were determined after 1, 2, 4 and 6 years of exposure under different climatic conditions.
The formation and development of corrosion products was followed by detailed analysis of samples exposed 0.5, 1, 2, 4 and 6 years using XRD, FTIR-spectroscopy and SEM-EDS. The data are discussed in view of current knowledge in the atmospheric corrosion of zinc, HDG and Zn-Al coated steel materials [1-6]
Table 1. Test sites in the exposure program

Code

Name

Country

Distance to Sea(m)

A

Brest
France
<5

B

Bohus-Malmön (I)
Sweden
<5

C

Bohus-Malmön (II)
Sweden
300

D

Ijmuiden
Netherlands
2600

E

Cadiz
Spain
750

F

Jiangjin
China
̴900 km

G

Ostrawa
Czech Republic
̴500 km

H

Dubai
UAE
2000

I

Daytona Beach
USA
100

J

Quindao
China
10

K

Wanning
China
100

L

Bangkok
Thailand
35 km

M

Sattahip
Thailand
10

N

Singapore
SIngapore
10

References
1-I. Odnevall, C. Leygraf, Corros. Sci. 34 (1993) 1213–1229.
2- I. Odnevall, C. Leygraf, Corros. Sci. 36 (1994) 1551–1567.
3- N. Le Bozec, D. Thierry, M. Rohwerder, Dan Persson, G. Luckeneder and L. Luxem, Effect of CO2 on the atmospheric corrosion of ZnMgAl coated steel, Corrosion Science, 74, pp 379-386, 2013

4- E. Diller, B. Lescop, S. Rioual, G Nguyen, D. Thierry and B. Rouvello, Initial formation of corrosion products on pure zinc and MgZn2 examined by XPS: Corrosion Science 79, pp 83-88, 2014.
5- D. Persson, N. Le Bozec, T. Prosek, D. Thierry, G. Luckenader , Corrosion Science Vol 90, pp 276-283, 2015.
6- D. Persson, D. Thierry, N. Le Bozec: Corrosion products formation on Zn55Al upon exposure in marine atmosphere, Corrosion Science, 720, 2011.
Effect of Molybdenum on Pit Initiation at Manganese Sulfide Inclusions in Stainless Steel
Authors: Nishimoto Masashi , Muto Izumi , Sugawara Yu , Hara Nobuyoshi 
Published: February 2020

Stainless steels sometimes suffer from pitting corrosion in chloride environments. The pit initiation sites for commercial stainless steels have been attributed to sulfide inclusions such as MnS. It is well known that addition of Mo enhances the pitting corrosion resistance of stainless steels, and the role of Mo has been studied extensively. However, it is still debated how Mo inhibits pitting corrosion of stainless steels. In this study, a microelectrochemical technique was applied to clarify the role of Mo addition in the inhibition of pit initiation at MnS inclusions in stainless steels.
Two re-sulfurized stainless steels were prepared by vacuum induction melting (50 kg ingot): one was Mo-free (18Cr-10Ni-0.8Mn-0.03S), and the other was Mo-added (18Cr-10Ni-2.3Mo-0.8Mn-0.03S). The ingots were hot-rolled. In these steels, S was added to form MnS inclusions. To reduce the delta-ferrite phase in the steels, they were heat-treated at 1273 K for 96 h, followed by hot-rolling at 1473 K from 20 mm down to about 12 mm in thickness. Additional heat-treatment was conducted at 1273 K for 96 h and at 1323 K at 0.5 h, and the steels were finally water-quenched. After heat-treatment, the steels were cut into specimens with dimensions of 15 mm × 25 mm × 5 mm. The specimens were abraded with a series of SiC papers up to 1500 grit and then were polished by a diamond paste down to 1 µm. Potentiodynamic polarization curves were measured in naturally aerated 0.1 M NaCl (pH 5.5) at 298 K. The electrode area was ca. 100 µm × 100 µm. All the potentials reported in this study refer to the Ag/AgCl (3.33 M KCl) electrode (0.206 V vs. standard hydrogen electrode at 298 K). The potential scan rate was 3.8 × 10–4 V/s (23 mV/min).
To analyze the effect of Mo on the pit initiation at the MnS inclusion, the anodic polarization curves were measured in 0.1 M NaCl. Figure 1a shows the polarization curves of a small area with the MnS inclusions in Mo-free and Mo-added specimens. Figures 1b and 1c show the SEM images of the inclusions in Mo-free and Mo-added specimens after polarization. The experiments were started at –0.2 V. The gradual increases in the current densities of both specimens above ca. 0.1 V are due to the anodic dissolution of the MnS inclusions. The large increase in the current density of the Mo-free specimen at 0.4 V was attributed to the stable pit initiation at the inclusion. As shown in Fig. 1b, a pit was initiated at the MnS/steel matrix boundary. On the other hand, the current density of the Mo-added specimen decreased to the level of the passive state of stainless steel above ca. 0.45 V. In Fig. 1c, no pit was observed in the Mo-added specimen even though the bare steel surface was exposed by the dissolution of the MnS inclusion. Mo species were estimated to be released from the exposed bare steel surface. This suggests that Mo species inhibited pit initiation at the MnS/steel boundary.

Figure 1
Battery Durability and Reliability Under Electric Utility Grid Operations:Representative Usage Aging
Authors: Baure George , Devie Arnaud , Dubarry Matthieu 
Published: February 2020

Battery Energy Storage Systems (BESSs) can facilitate renewable energy sources integration onto the grid. For this application, these systems are expected to last for a decade or more, but the actual battery degradation under different real-world conditions is still largely unknown. In this work, three years of lithium titanate BESS usage in Hawai'i were analyzed. In addition, the representative usage was subjected on individual cells under controlled laboratory conditions to study the degradation mechanisms and enable life prognosis.
The BESS was found to be operational 90% of the time and it stored a cumulative 1.5 GWh of energy, which represented more than 5000 equivalent full cycles on the cells. From this BESS usage data, an initial estimate of BESS degradation was provided and a representative duty cycle was developed. The analysis of the maintenance cycles indicated that these 5000 equivalent cycles induced an estimated 5-10% degradation of the single cells. The battery duty cycle was characterized based on 5 parameters: pulses duration, pulses intensity (current), state of charge (SOC) swing range, SOC event ramp rate, and temperature. The average usage consisted of several 9-second C/2 charge and discharge pulses organized to generate 5% SOC swings with a 0.75% SOC/min ramp rate at 35°C. However, extreme values such as currents up to 4C, swings of 100% SOC, and temperatures above 50°C were also recorded.
Laboratory testing and analysis, in conjunction with a more thorough SOH estimation protocol, resulted in a detailed description of degradation that improved the predictions of the remaining useful battery life. Based on the BESS representative usage profile, cycle-aging and calendar-aging experiments were designed to test the degradation of the associated Li-ion cells in a controlled fashion. It was proven that the cell temperature history had the strongest impact on battery degradation followed by the C-rate and the state of charge. Interestingly, the impact of SOC, both on the cycle-aging and the calendar-aging experiments, was revealed to be counterintuitive. During cycle aging, small SOC swings were more detrimental than larger ones. During calendar aging, batteries lost capacity faster at low SOC than at high SOC. The associated degradation mechanisms and their path dependency were analyzed using incremental capacity analysis.