bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understand the Hydrogen Electrode Reaction for Proton Conducting SOFC Via Controlled Poisoning Experiments Using Hydrogen Sulfide and Carbon Dioxide
Authors: Sun Shichen , Cheng Zhe 
Published: February 2020

The hydrogen electrode reaction for conventional solid oxide fuel cells (SOFC) has been widely studied and well understood. In comparison, electrochemical behaviors for hydrogen electrode reaction of proton conducting SOFC are often distinctly different and there are still many unknowns about the fundamental kinetics and mechanism for such reaction. For example, it is well known that the hydrogen electrodes for conventional oxide ion SOFC, which consist of oxygen ion conducting oxides and Ni, are susceptible to poisoning by even sub-ppm level hydrogen sulfide (H2S). On the other hand, literature suggests that the hydrogen electrodes for proton conducting SOFC, which contains proton conducting oxides and Ni, show much better resistance against H2S. By understanding the origin of differences like this, new insights of the fundamental reaction mechanism for the hydrogen electrode of proton conducting SOFC can be obtained. In this study, electrochemical tests based on the concept of “controlled poisoning”, which is to selectively poison specific parts of the hydrogen electrode using low concentration of either H2S as a “Ni poison” or CO2 as a “proton conducting oxide poison”, are carried out to understand the fundamentals about the hydrogen electrode reaction for proton-conducting SOFCs. In particular, anode-supported cell with the configuration of Ni-BaZe0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb)/BZCYYb/LSCF and anode symmetrical cell with the configuration of Ni-BZCYYb/BZCYYb/BZCYYb were subject to ppm-level H2S and low percentage level CO2, and the electrochemical responses for both types of cells are characterized. Preliminary results show that, contrary to the Ni-based hydrogen electrode for conventional SOFC, the Ni-BZCYYb hydrogen electrode for proton conducting SOFC shows much better resistance against “sulfur poisoning” while gets poisoned by CO2 at low percentage level. Results for experiments aimed at understanding such differences will be presented and the implications on what the electrocatalytic roles of proton conducting oxides play in the hydrogen electrode reaction for proton conducting SOFC will be discussed.
Bulk Defect Chemistry of PCFC Cathode Materials: Discussion of Defect Interactions
Authors: Zohourian Reihaneh , Merkle Rotraut , Maier Joachim 
Published: February 2020

In order to extend the reactive zone for oxygen reduction to water beyond the gas/electrode/electrolyte three phase boundary, cathode materials for proton conducting ceramic fuel cells should exhibit a certain proton conductivity, exceeding 10-5 S/cm [1]. Proton uptake into (Ba,Sr,La)(Mn,Fe,Co)O3-
d perovskites considered as cathode material can occur by incorporation of H2O (for ) or by incorporation of only H (for ) assuming ideally dilute defect concentrations [2,3]. These two regimes can be identified by thermogravimetric investigations over an extended range of pO2, pH2O and temperature.
Independent of the actual proton incorporation regime the proton concentrations in (Ba,Sr,La)(Fe,Co)O3-
d cathode materials amount to less than 3% [3]. They are much lower than for acceptor-doped Ba(Zr,Ce)O3-xelectrolytes, which remain completely hydrated (10-20% protons) up to about 400-500 °C. Correlations between cation composition and proton uptake will be explored [6]. The basicity of the oxide ions is known to favour proton uptake in electrolyte materials. In p-type conducting and redox-active cathode materials, additional defect interactions between protons and electron holes lead to a perceptible decrease of proton uptake already for low hole concentrations. This is probably related to the partially covalent bonding between the transition metal and oxygen, by which one localized hole affects the basicity of six adjacent oxide ions.
Proton mobility in cathode materials has so far only been measured for Ba0.5Sr0.5Fe0.8Zn0.2O3-
d [4], where it is comparable to that in Y-doped BaZrO3-x electrolytes. The estimated proton conductivity of » 10-3 S/cm at 350-450 °C [1] suffices to transport protons from the electrolyte through the dense cathode film to the gas interface, as evidenced from the diameter dependence of microelectrode resistances. The reduction of O2 to water can in principle proceed without oxygen incorporation into the cathode material. The measured pO2 dependence of the effective rate constant indicates that molecular oxygen species participate in the rate determining step. From the pH2O dependence for Ba0.5Sr0.5Co0.8Fe0.2O3-
d microelectrodes we conclude that protonated oxygen species appear only after this step [5]. Together, these findings suggest that for Ba0.5Sr0.5Fe0.8Zn0.2O3-
d and Ba0.5Sr0.5Co0.8Fe0.2O3-
dthe oxygen reduction to water proceeds via intermediate uptake of O into surface oxygen vacancies.
[1] R. Merkle, D. Poetzsch, J. Maier, ECS Transact. 66(2) (2015) 95
[2] D. Poetzsch, R. Merkle, J. Maier, Adv. Funct. Mater. 25 (2015) 1542
[3] D. Poetzsch, R. Merkle, J. Maier, Faraday Discussions 182 (2015) 129
[4] D. Poetzsch, R. Merkle, J. Maier, Phys. Chem. Chem. Phys. 16 (2014) 16446
[5] D. Poetzsch, R. Merkle, J. Maier, J. Electrochem. Soc. 162 (2015) F939
[6] R. Zohourian, R. Merkle, J. Maier, Solid State Ionics doi:10.1016/j.ssi.2016.09.012
(Invited) Solid Oxide Fuel Cell Powered Small Unmanned Aerial Systems for Long Endurance
Authors: Chu Deryn 
Published: February 2020

Solid Oxide Fuel Cell Powered Small Unmanned Aerial Systems

For Long Endurance

Deryn Chu(1), Rongzhong Jiang(1), Zachary Dunbar(1) and Kevin Chu(2)

U. S. Army Research Laboratory
2800 Powder Mill Rd., Adelphi, MD 20783-1107

U. S. Army CERDEC. CP&I/Power Division

5100 Magazine Rd.
Aberdeen Proving Ground, MD 21005
Small unmanned aerial systems (SUASs) have great potential for many different applications (1-3). The SUASs are light-weight, man-portable, and capable of carrying payloads. SUASs can be broadly classified by their performance characteristics such as engine type, weight, speed, and endurance. Currently, small UASs are powered by lithium-ion or lithium polymer batteries; however, flight endurance is limited and requires frequent battery replacement. Frequent battery replacement is due to low capacity and energy density (less than 200Wh/Kg). Numerous research and development efforts have focused on alternative power sources. These alternative power sources include technologies such as solar cells and hydrogen based polymer electrolyte membrane fuel cells. Recently, a long endurance flight time for SUASs have been demonstrated through propane fueled solid oxide fuel cell (SOFC) systems. In this presentation, we address propane fueled SOFC to power a ~20lbs unmanned aerial system for 8hrs (4x improvements over the competing battery technology).
Reference:

http://www.youtube.com/watch?v=98BIu9dpwHU

http://www.youtube.com/watch?v=98BIu9dpwHU&feature=player_detailpage

https://www.youtube.com/watch?v=-CYT4PFV_Hs
Model-based Analysis of Carbon Corrosion in Start-up/Shutdown, Fuel Starvation, and Voltage Reversal of a Polymer Electrolyte Fuel Cell
Authors: Chen Jixin , Hu Jingwei , Waldecker James 
Published: February 2020

Support carbon corrosion has been identified as a major degradation source in a polymer electrolyte fuel cell. Start-up/Shutdown (SUSD) [1], fuel starvation [1], and voltage reversal [2] are widely-known conditions that can trigger non-negligible carbon corrosion in the anode or cathode. SUSD carbon corrosion is associated with current reversal while there is no external load. As a comparison, fuel starvation due to nitrogen blanketing and/or water droplets in an operating cell also can result in similar current reversal. The region with current reversal, i.e., a proton flux from the cathode to the anode, features extremely severe hydrogen depletion in the anode and occurrence of carbon corrosion in the opposite cathode. Differently, the voltage reversal occurs in one or a few cells (not all) in a stack. Those cells show negative cell voltages under extended reversal, but the overall current is flowing as usual thanks to the other normal cells in the stack. The voltage reversal leads to carbon corrosion in the anode, as compared to carbon corrosion in the cathode for current reversal. The local potential for carbon corrosion could be much more severe in an extended voltage reversal than that in SUSD.
This paper/presentation will elucidate the fundamental differences of these three carbon corrosion scenarios with model simulation and analysis. The models [3, 4] will also be used to perform comprehensive parametric studies, aiming to understand the impacts from key design and operating parameters including pseudo-capacitance, selective oxygen evolution reaction (OER) catalysis, reactant gas flow rate, temperature, membrane hydration state, and current load drawn from the stack. It is anticipated to shed light on the otherwise confusing carbon corrosion scenarios in a polymer electrolyte fuel cell and the fundamental ideas for alleviation strategies. For example, in the fuel starvation induced carbon corrosion, the simulation indicates that the decreasing cell voltage due to diluted hydrogen concentration appears to limit the local potential in the cathode and associated carbon corrosion. In the SUSD carbon corrosion, pseudo-capacitance from Pt oxidation may raise another concern in parallel to carbon corrosion. In general, a reduced temperature or enhanced OER activity is helpful in reducing carbon corrosion.

Figure 1
(Invited) Hydrogen Fuel Cells for Small Unmanned Air Vehicles
Authors: Swider-Lyons Karen 
Published: February 2020

Dr. Russ Kunz was known as an early pioneer of fuel cell research in the corporate research environment, carrying out and publishing basic and applied research toward the improvement of specific corporate applications. This talk will describe how similar research on polymer electrolyte membrane fuel cells (PEMFCs), or hydrogen fuel cells, is being developed at the U.S. Naval Research Laboratory (NRL), the corporate research laboratory for the U.S. Navy.
The U.S. Navy is interested in unmanned systems for numerous reasons, such as offering reduced manning and creating the ability to carry out missions in environments hostile to humans. However, numerous challenges remain, such as the limited endurance of battery-electric vehicles. At NRL, we targeted the limited endurance of battery-electric unmanned air vehicles (UAVs) proposing hydrogen fuel cells as a path to long-endurance propulsion. NRL developed the Ion Tiger UAV, first using a 1.1-kg 550-Watt fuel cell built by Protonex Technology Corporation in the power train. The Ion Tiger flew for 26 hours on hydrogen fuel cell propulsion in November 2009 using compressed hydrogen gas as the fuel, and 48 hours in April 2013 using liquid hydrogen fuel. More recently, NRL has designed and built in house a flight-weight, modular 1.5 to 5 kW PEMFC using metal bipolar plates as the backbone – first with 3D printed titanium bipolar plates, and more recently using automotive-grade, formed stainless steel bipolar plates. We have also developed the methodology to make catalyst-coated membranes in house to speed development of new designs.
The overall success of our hydrogen UAV program is due to advances in materials, electronics, and thermal management, integrated into an aerodynamically efficient package. The resulting fuel cell–powered UAVs are relatively small (35 to 100 lbs) but they are quiet and efficient, allowing them to do “big airplane” missions. The full system approach, with basic and applied research as its foundation, is clearly a tribute to the corporate research approach that Dr. Kunz espoused.
Computationally Driven Oxygen Stabilization By Cation Substitution in Lithium-Rich Cathode Material
Authors: Wynn Thomas Andrew , Fang Chengcheng , Zhang Minghao , Liu Haodong , Davies Daniel M , Meng Ying Shirley 
Published: February 2020

Lithium-rich layered cathode materials, where excess lithium occupies transition metal (TM) sites in the TM layer, have shown capacities well beyond commercially available traditional layered cathodes. This is largely attributed to redox behavior of oxygen within the cathode, and has recently been examined computationally1. However this increased capacity is accompanied by a high degree of irreversible capacity loss in first cycling, voltage decay, and low rate capability. This is partially attributed to an oxygen release mechanism, where oxygen vacancy formation accompanies delithiation, rather than the redox of TM ions2. Numerous methods have been attempted to prevent the release of oxygen from the lattice, including TM substitution, morphology control, and surface coating. In this work, we employ density functional theory to calculate the oxygen vacancy formation energy in layered lithium-rich nickel manganese oxide with a variety of cation dopants. Computational results elucidate the impact of doping on the system, and provide rationale for these behaviors. These calculations further describe the impact of local TM bonding environment on specific oxygen sites, rationalizing their relative vacancy formation energies. Driven by these computational results, we experimentally introduce relevant dopants into our cathode materials and observe electrochemical cycling changes commensurate with the predicted changes. Characterization methods verify the predicted oxidation states and incorporation of the relevant dopants.
1. Seo, D. et al. "The structural and chemical origin of the oxygen redox activity in layered and cation-disordered Li-excess cathode materials." Nat. Chem.8, 1–6 (2016).
2. Hy, S. et al. "Performance and Design Considerations For The lithium Excess Layered Oxide Positive Electrode Materials For Lithium Ion Batteries." Energy Environ. Sci. 9, 1931–1954 (2016).
Revealling the Structure of Catalyst for Diameter and Chirality Selective Growth of Single-Walled Carbon Nanotube Directly on SiO2
Authors: Xiang Rong , Kumamoto Akihito , An Hua , Ikuhara Yuichi , Maruyama Shigeo 
Published: February 2020

Here we present our recent progress on controlled growth of single-walled carbon nanotubes (SWNTs) by our alcohol catalytic chemical vapor deposition (ACCVD),[1] and a technique for revealling the structure of catalyst directly on SiO2 film.[2]
With Co-Cu binary catalyst, a novel combination recently proposed, we are able to synthesize vertically aligned (VA-) SWNTs with diameter tunable down to 1 nm, which is so far smallest for VA-SWNT arrays.[3] Chirality selective growth of SWNTs achieved in ACCVD from sputtered Co-W catalyst. This sputtered Co-W catalyst is able to grow SWNTs uniformly on entire substrate with a (12,6) enrichment of 70%.[4]
To clarify to growth mechanism in binary catalyst, we propose an in-plane TEM approach, which enables a direct characterization of catalyst particles with atomic resolutions on a MEMS-fabricated thin SiO2 film. Since no transfer or any post treatments are needed, the most original morphology is preserved. By this technique we confirm that, with the addition of Cu, much smaller Co particles form epitaxially on Cu and produce all sub-nm vertically aligned SWNTs. In Co-W, selective area electron diffraction (SAED) suggests an intermediate Co6W6C structure that is possibly associated with growth selectivity. High-angle annular dark-field imaging (HAADF) reveals the the junction between metallic W and Co-W.
[1] S. Maruyama*, R. Kojima, Y. Miyauchi, S. Chiashi and M. Kohno, Chem. Phys. Lett., (2002), 360-3-4, 229-234.
[2] R. Xiang, A. Kumamoto, Y. Ikuhara, S. Maruyama, et al., to be submitted.
[3] K. Cui, A. Kumamoto, R. Xiang, H. An, B. Wang, T. Inoue, S. Chiashi,Y. Ikuhara, S. Maruyama*, Nanoscale, (2016), 8-3, 1608-1617.
[4] H. An, A. Kumamoto, H. Takezaki, S. Ohyama, Y. Qian, T. Inoue, Y. Ikuhara, S. Chiashi, R. Xiang*, S. Maruyama*, Nanoscale, (2016), 8, 14523-14529.
This work was supported by JSPS KAKENHI Grant Numbers JP25107002, JP15H05760, JP15K17984, and IRENA Project by JST-EC DG RTD, Strategic International Collaborative Research Program, SICORP. Part of this work is based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). We also acknowledge supports from Advanced Characterization Nanotechnology Platform of the University of Tokyo, supported by "Nanotechnology Platform" of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
(Invited) Honoring and Remembering Robert H. Hauge - Carbon Nanotube Research Contributions
Authors: Adams W. Wade 
Published: February 2020

Robert Hugh Hauge was an extraordinary scientist and an amazing personality, whose contributions will be highlighted in this opening presentation of the session in his honor. This Wisconsin country boy was educated at Loras College and the University of California at Berkeley, graduating with a Ph.D. under renowned high-temperature chemist Leo Brewer. His 1966 dissertation on Spectroscopy of CaO was a brief but definitive 46 pages. Bob was attracted to join Rice University by former UC Berkeley postdoc John Margrave, who allowed him to continue his interest in high-temperature chemistry but also expanded his expertise into fluorine chemistry. He ultimately joined Nobelist Rick Smalley's team, where he added creativity and excellence to the rapidly expanding field of carbon nanotechnology. Bob Hauge became known not only as an excellent and highly productive chemist, but also as a mentor for many students, with whom he loved to engage in debate and technical arguments to advance mutual learning and understanding of new phenomena. He was the 13th highest cited author in chemistry in the world in the first decade of the 2000s and completed his 50th year at Rice University in 2015, entirely supported by "soft" money.He loved his science and all of us "students," attending group meetings until a week before his death on March 17, 2016.

Figure 1
Carbon-Based Electrodes for High Energy Electrochemical Capacitors
Authors: Liu Tianyuan , Gupta Kishor , Lee Seung Woo , Kumar Satish 
Published: February 2020

Electrochemical capacitors (ECs) have been considered as one of the most promising electrochemical energy storage devices owing to their several advantages such as high power density and long cycle life. In ECs, charges are stored on the surface of porous electrodes, therefore, the available energy density strongly depends on the microstructure and surface chemistry of the electrodes. However, state-of-the-art ECs only exhibit an energy density of 4–5 Wh/kg by using the electric double layer capacitance, which is still considerably lower than that of Li-ion batteries.
In this presentation, we will show our recent results on enhancing the energy density of carbon-based electrodes for capacitive energy storage. Firstly, for replacing the conventional activated carbon in ECs, we developed high surface area carbons with a surface area of 3550 m2/g from polyacrylonitrile via a low-cost and scalable process.1 The high surface area carbon exhibited a capacitance of 150 F/g in 1-ethyl-3-methylimidazolium tetraﬂuoroborate (EMIMBF4) and 210 F/g in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC). The composite electrodes consisting of high surface area carbon and carbon nanotubes delivered a high capacitance of~ 170 F/g in symmetric configurations, and a high capacity of~ 150 mAh/g in asymmetric configurations against lithium metal with excellent rate-performance at practical mass loading and bulk densities.
Improving volumetric performance has been one of the major challenges in nanostructured carbon electrodes for capacitive energy storage. Recently, we developed a simple hydrothermal oxidation method for functionalizing carbon nanotube films using dilute nitric acid.2 This method shows high efficiency in densifying as-assembled single-walled carbon nanotubes (SWNT) films from 0.63 g/cm3 to 1.02 g/cm3, as well as introducing a considerable amount of redox-active oxygen functional groups on the surface of the SWNTs. The functionalized SWNT electrodes deliver high volumetric as well as gravimetric capacities, 154 Ah/L and 152 mAh/g, respectively, owing to the surface redox reactions between the introduced oxygen functional groups and Li ions. In addition, the functionalized electrodes also exhibit a remarkable rate capability by retaining its high capacity of 94 Ah/L (92 mAh/g) at a high discharge rate of 10 A/g.

References:
(1) Gupta, K.; Liu, T.; Kavian, R.; Chae, H. G.; Ryu, G. H.; Lee, Z.; Lee, S. W.; Kumar, S. Journal of Materials Chemistry A
2016, 4, 18294.
(2) Liu, T.; Davijani, A. A. B.; Sun, J.; Chen, S.; Kumar, S.; Lee, S. W. Small
2016, 12, 3423.
Quantum Near-Field Effects in Hybrid Carbon Nanotube Systems
Authors: Bondarev Igor 
Published: February 2020

Physical understanding of near-field processes in complex hybrid nanostructures of reduced dimensionality is a natural prerequisite for the development of future generation advanced nanomaterials and devices. I present two examples of how the near-field processes can drastically affect optical and transport properties of hybrid carbon nanotube structures.
First is the Surface Enhanced Raman Scattering (SERS) effect for a two-level atomic system (TLS) coupled to a low-energy interband plasmon resonance of a carbon nanotube (CN) [1]. Here, the SERS comes about as a strong-coupling near-field effect in which the local-field enhancement occurs due to the interband plasmon excitation when the TLS is located near the CN surface and its transition energy matches a CN local photonic DOS resonance. Previously, most of the applications of CNs to enhance the Raman scattering have been to decorate them with metallic nanoparticles, to use metal plasmons as spectroscopic enhancers with CNs only serving as their supporters [2,3]. Here, individual CNs are shown to result in the SERS effect due to their intrinsic interband plasmon modes [1]. The effect may be used to detect individual atomic type objects trapped near nanotubes. More advanced applications may include highly efficient CN based SERS substrates for single molecule/atom/ion detection, precision spontaneous emission control, and quantum optical manipulation.
Second is the plasmon mediated electron transport in hybrid metal-semiconductor CN systems composed of single wall semiconducting CNs with encapsulated metallic atomic wires (AWs) [4]. Encapsulating metallic wires of just one atom thick into a single wall CN, metallic or semiconducting, is known to drastically alter the transport properties of the compound hybrid system [5]. Our theory and numerical simulations predict generic Fano resonances in charge transfer through the hybrid metal-semiconductor CN system, whereby the strong plasmon mediated AW-CN near-field interaction blocks some of the pristine AW transmission band channels to open up new coherent channels in the CN bandgap outside the AW transmission band [4]. This effect can be used to optimize charge transfer in hybrid nanodevices built on metal-semiconductor nanotube systems.
I.V.B. acknowledges the US DOE grant support (DE-SC0007117). Part of this work (electron transport) was done in collaboration with M.F.Gelin of TU-Munich, Germany, whose visit to North Carolina Central University was sponsored by the US NSF grant ECCS-1306871.

References

[1] I.V.Bondarev, Optics Express 23, 3971 (2015)
[2] Y.-C.Chen, R.J.Young, J.V.Macpherson, and R.Wilson, J. Raman Spectrosc. 42, 1255 (2011)
[3] Y.Sun, K.Liu, J.Miao, Z.Wang, B.Tian, and L.Zhang, NanoLett. 10, 1747 (2010)
[4] M.F.Gelin and I.V.Bondarev, Phys. Rev. B 93, 115422 (2016)
[5] R.Nakanishi, R.Kitaura, P.Ayala, H.Shiozawa, K.de Blauwe, P.Hoffmann, D.Choi, Y.Miyata, T.Pichler, and H.Shinohara, Phys. Rev. B 86, 115445 (2012)