bluuebunny/crossref_metadata_2025 huggingface dataset:
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).
The Rod-Shaped Crystallographic Texture of FCG(Full Concentration Gradient) Cathode Material with Long-Term Cycling Stability for Xev Application
Authors: Kim Un-Hyuk , Lee Eung-Ju , Yoon Chong seung , Myung Seung-Taek , Sun Yang-Kook
Published: February 2020

Al is introduced into a compositionally graded cathode with average composition of Li[Ni0.61Co0.12Mn0.27]O2 (FCG61) whose Ni and Mn concentrations are designed to vary continuously within the cathode particle. The Al-substituted full concentration gradient (Al-FCG61) cathode is tested for 3000 cycles in a full-cell, mainly to gauge its viability for daily charge/discharge cycles during the service life of electric vehicles (≈10 years). The Al-substitution enables the Al-FCG61 cathode to maintain 84% of its initial capacity even after 3000 cycles. It is demonstrated that the Al-substitution strengthens the grain boundaries, substantiated by the mechanical strength data, thereby delaying the nucleation of microcracks at the phase boundaries which is shown to be the main reason for the cathode failure during long-term cycling. It also shows that the Al-substitution decreases the cation mixing and suppresses the deleterious formation of the secondary phase that likely initiates the microcracks. Unlike an NCA cathode, whose depth of discharge (DOD) must be limited to 60% for long-term cycling, the proposed Al-FCG61 cathode is cycled at 100% DOD for 3000 cycles to fully utilize its available capacity for maximum energy density and subsequent reduction in cost of the battery.
Sulfur Immobilization By “Chemical Anchor” to Suppress the Dissolving of Polysulfides in Lithium-Sulfur Batteries
Authors: Zeng Zhipeng , Yan Jianhua , Liu Xingbo
Published: February 2020

Embedding sulfur species in carbonaceous materials or conductive polymer network has been widely regarded as the major approach to alleviate the lithium polysulfide dissolution in lithium-sulfur batteries’ cathodes. However, these conductive materials (as coating layer or host material) can only physically restrain polysulfides, since they usually provide open nanopores which could still be accessed by electrolyte. Therefore, the physical barrier can only slow down the escape of polysulfide but not eliminate the issue. Utilizing “chemical anchor” to develop sulfur host materials with strong chemical binding for polysulfide, rather than solely relying on the high surface area or pore structure for the physical confinement, is extensively explored recently. This review details the recent advances in developing active materials with strong chemical interactions between sulfur and host materials, covering sulfurized carbonaceous materials, organic sulfides, metal-stabilized sulfur and their potential application in energy storage. We also summarize our development of functional gradient C-S composite cathodes with high sulfur loading and good capacity retention.
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
(Invited) Recent Advances in SWCNT Analytical Spectroscopy
Authors: Weisman R. Bruce , Kadria-Vili Yara , Sanchez Stephen R. , Bachilo Sergei M.
Published: February 2020

Since the 2002 assignment of absorption and emission transitions to specific (n,m) structures, optical spectroscopy has offered the potential for simple, detailed structure-resolved characterization of SWCNT samples. However, this goal has not been fully realized because of incomplete spectroscopic and photophysical knowledge and a lack of specialized instrumentation. We describe here recent progress in overcoming these problems to enable quantitative sample analysis through combined fluorescence and absorption spectroscopy. One important step was determining absolute E11 absorption cross sections (molar absorptivities) for a number of common (n,m) species. This was achieved by using a direct counting method to calibrate the absolute concentrations of reference samples, and then by extending the list of measured cross sections through variance spectroscopy determinations of (n,m)-resolved particle concentrations in mixed samples. To properly interpret fluorimetric data, we have measured, interpreted, and modeled emission spectra and excitation spectra for a range of semiconducting (n,m) species. Combinations of single particle and ensemble spectroscopies were used for these studies. The models were extrapolated to other (n,m) species to predict E11 line widths and shapes plus the positions, amplitudes, and widths of spectral sidebands. When combined with data on structure-dependent fluorimetric efficiencies, the results allow fluorescence spectra of nanotube mixtures to be simulated as a sum of contributions from multiple (n,m) species of determined relative concentrations. To convert those concentrations from relative into absolute values, the absorption spectrum of a mixed sample is simulated as a background function plus components determined from the fluorescence emission and excitation profiles for the (n,m) species that were found to be present. Then the separate E11 (n,m) absorbance components are divided by their structure-specific absorption cross sections to find absolute species concentrations. The overall process allows quantitation of semiconducting (n,m) concentrations from simple and quick spectral measurements.
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.
(Invited) Prospects for Wavelength-Tunable Photodetectors with Carbon Nanomaterials
Authors: Léonard François
Published: February 2020

Dynamic wavelength tunability has long been the holy grail of photodetector technology. Because of their atomic thickness and unique properties, carbon nanomaterials such as carbon nanotubes and graphene open up new paradigms to realize this concept, but so far this has been elusive experimentally. In this presentation, I will discuss the value behind tunable photodetectors, and present detailed quantum transport modeling of photocurrent in realistic devices, including full simulations of the electromagnetic fields. Our work shows that wavelength tunability is possible by dynamically changing the gate voltage, and we reveal the phenomena that govern the behavior of this type of device and show significant departure from the simple expectations based on vertical optical transitions. We find strong focusing of the electromagnetic fields at the contact edges over the same length scale as the band-bending. Both of these spatially-varying potentials lead to an enhancement of non-vertical optical transitions, which dominate even the absence of phonon or impurity scattering. We also show that the vanishing density of states near the Dirac point leads to contact blocking and a gate-dependent modulation of the photocurrent. We further highlight the challenges in realizing this technology by studying the impact of charge fluctuations on optical absorption.
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)
All-in- One Graphene-Based Composite Fiber Supercapacitor
Authors: Liu Yangshuai , Rasenthiram Lathankan , Lim Lucas , Liu Wenwen , Yu Aiping
Published: February 2020

Graphene fibers (GF) have attracted great interest in wearable electronics applications due to their excellent mechanical flexibility and superior electrical conductivity. Herein, a graphene/MnO 2 composite hybrid supercapacitor fiber device has been devised. The unique design of this device overcomes the inconvenience and short circuit risk of conventional designs. The backbone of the device consists of GF that not only provides a durable scaffold for the entire device, but also ensures fast electron transfer during charge-discharge. The introduction of a MnO 2 film with abundant active sites enhanced the pseudocapacitance dramatically, compared to pristine GF. The entire device exhibits outstanding mechanical strength as well as good electrocapacitive performance with a volumetric capacitance of 29.6 F cm-3 at 2 mv s-1 . The capacitance of the device didn’t fade at all under bending testing from 0° to 150°, while the capacitance retention was kept 93% after 1000 cycles. These unique features make this device a promising candidate for applications in wearable fabric supercapacitors.
Controlled Synthesis of Homogeneous MnCO3 Hollow Nanostructures for Supercapacitor Application
Authors: Piraman Shakkthivel , Alagar Srinivassan , Madhuvilakku Rajesh
Published: February 2020

Abstract

Novel hollow nanospheres/cubes of MnCO3 nanostructures have been synthesized successfully by adopting co-precipitation method. Uniform hollow MnCO3 nanospheres/cubes was obtained by controlling the reaction kinetics in the nucleation process of forming manganese carbonates simply by employing NH4HCO3 and NH4SO4 as precipitating agents. Physicochemical and electrochemical performances of the hollow nanospheres/cubes MnCO3 samples are investigated by x-ray diffraction (XRD) scanning electron microscope with energy diffraction x-ray spectroscopy (EDXS), transmission electron microscopy (TEM) and electrochemical techniques. The results show that the hollow nanospheres/cubes of MnCO3 samples have a typical R-3C Rombohedral structure. Especially, the hollow MnCO3 nanosphere sample has excellent super capacitor performance. It delivers a specific capacity of 520 F/g between -0.3 and 0.9 V Vs SCE with capacity retention of 99 % over the 2000 cycles at a current density of 8 A/g at room temperature. Thus, the MnCO3 hollow nanosphere electrode will be a promising energy storage material for advanced supercapacitor applications.

Figure 1
TiP2O7 Exhibiting Reversible Insertion of Sodium Ions in an Aqueous Environment
Authors: Yee Grace , Whitacre Jay , Shanbhag Sneha , Chang Jiang , Carlisle Kristen
Published: February 2020

Aqueous sodium ion batteries are attractive for large-scale energy storage due to their low cost, intrinsic safety and environmental friendliness [1,2]. A key challenge in designing aqueous batteries is creating electrode pairs that operate within the stable potential window of water, with anode material selection being particularly challenging. Furthermore, good materials for sodium ion cycling are limited [2,3]. TiP2O7 presents a promising anode material due to its lower intercalation/deintercalation potentials, allowing for more optimized use of an aqueous electrolyte’s stability window [1-3]. TiP2O7 is typically reported to exclusively cycle lithium ions, showing no capacity in sodium aqueous electrolytes in cyclic voltammetry tests [3]. One report demonstrated that a low temperature polymorph of TiP2O7 exhibits reversible cycling of sodium ions in an organic electrolyte [4].

In this work, the reversible insertion of sodium ions in TiP2O7 as the anode material in an aqueous battery is demonstrated. Several polymorphs of TiP2O7 are synthesized using a high temperature solid-state route and a low temperature sol gel route. In addition to physical characterization, the materials are electrochemically characterized in an aqueous 1M Na2SO4 electrolyte against Na0.44MnO2 cathode material. While no capacity for sodium ion cycling is reflected in cyclic voltammetry tests of these TiP2O7, all polymorphs exhibited reversible cycling of sodium ions in constant current galvanostatic cycling with potential limitation. To our knowledge, this is the first report of solid-state synthesized TiP2O7 reversibly cycling sodium ions. Specific capacity is found to be positively correlated with both crystallite size and lattice parameter. A full cell rate study with three electrode data in aqueous Na2SO4 electrolyte is presented.

Acknowledgments

This work is supported by Carnegie Mellon University and Aquion Energy Inc.

References

[1] W. Wu, S. Shanbhag, A. Wise, J. Chiang, A. Rutt, J. Whitacre, “High Performance TiP 2 O 7 Based Intercalation Negative Electrode for Aqueous Lithium-Ion Batteries via a Facile Synthetic Route,” Journal of The Electrochemical Society, 162 (2015).

[2] H. Wang, K. Huang, Y. Zeng, S. Yang, L. Chen, “Electrochemical properties of TiP 2 O 7 and LiTi 2 (PO 4 ) 3 as anode material for lithium ion battery with aqueous solution electrolyte,” Electrochemica Acta, 52 (2007) 3280-3285.

[3] L. Chen, Q. Gu, X. Zhou, S. Lee, Y. Xia, Z. Liu, “New-concept batteries based on aqueous Li + /Na + mixed-ion electrolytes,” Scientific Reports, 3 (2013).

[4] P. Senguttuvan, G. Rousse, J. Oro-Sole, J.M. Tarascon, M.R. Palacin, “A low temperature TiP 2 O 7 polymorph exhibiting reversible insertion of lithium and sodium ions,” Journal of Materials Chemistry A, 1 (2013).
(Invited) Superconformal Film Growth:Impact of Additives and Deposition on Hydrophilicity
Authors: Moffat Thomas P. , Liu Guokun , Zou Shouzhong , Richter Lee , Ou Yang Liang-Yueh , Wheeler Daniel , Josell Daniel
Published: February 2020

State of the art manufacturing of semiconductor devices involves electrodeposition of copper for device wiring and more recently for through-silicon-vias (TSVs). The process depends on the use of electrolyte additives that affect the local deposition rate thereby resulting in superconformal, or bottom–up “superfilling” of trenches and vias. Quantitative descriptions based on mass balance analysis of the additives and their effect on the local deposition rate have been shown to be effective for describing Damascene feature filling (CEAC, Curvature Enhanced Coverage Mechanism) and larger scale TSV filling (S_NDR, S-shaped negative differential resistance models). Despite the success of these processes much remains to be known concerning the detailed molecular nature of the competitive co-adsorption processes involved in both the suppression and acceleration of the metal deposition reaction. Accordingly, the application of in situ surface science tools such as in situ STM and SEIRAS towards a better understanding of the additive interaction will also be detailed. These studies show that the addition of Cl- to an acidified CuSO4 electrolyte displaces co-adsorbed SO4
2--water species from the Cu surface. The rapidly formed ordered halide overlayer disrupts the adjacent solvent hydrogen bond network to create a hydrophobic interface that facilitates co-adsorption of polyethers, such as poly(ethylene glycol) (PEG), polyoxamers (EPE), polyoxamines (TET), that are known to block the Cu deposition reaction by limiting access of Cu2+
aq to the underlying metal surface. When challenged by bis-(3-sodium sulfopropyl disulfide) (SPS), or mercaptopropane sulfonate (MPS), competitive disulfide/thiol adsorption leads to disruption and displacement of the polymer suppressor. The disulfide/thiol head group tethers SPS/MPS to the surface, via Cu adatoms or defects in the Cl- covered surface, while the SO3
- terminal group makes the interface hydrophilic which accounts for its anti-suppressor action. The potential dependence of competitive SPS adsorption and its dependence on the strength of polyether adsorption were measured.
(Electrodeposition Division Early Career Investigator Award Address) Magnetocapacitive Carbon Nanocomposites
Authors: Zhu Jiahua
Published: February 2020

The global energy supply is transforming from conventional fossil energy to sustainable energy. Sustainable energy species, for example, solar, wind, and hydro energy, are in an unsteady state and fail to provide a stable energy supply. Energy storage units can collect these unsteady state energies and output as stable energy supply. However, current energy storage units face significant challenges to provide both high-energy density and high-power density. To achieve high energy storage performance of electrochemical capacitor, existing research efforts mainly focus on (1) synthesizing new electrode materials to enlarge specific capacitance, and (2) designing asymmetric capacitor configuration and utilizing organic electrolytes to expand the working potential range. Without changing any internal components, we recently observed a significant capacitance enhancement of up to 155% by solely applying a small external magnetic field (0.072 Tesla). The magnetic field induced capacitance change is called magnetocapacitance.

In this talk, small magnetic field induced capacitance change on carbon nanocomposites will be discussed. Two processes, conventional- and microwave- annealing, were introduced to manufacture desired electroactive carbon nanocomposites decorated with pseudoactive metal oxide nanostructures (for example, Fe2O3, NiO and Co3O4). Their magnetocapacitances will be measured and compared. The proposed mechanisms will be interpreted by capacitor internal resistance change (solution resistance, charge transfer resistance and leakage resistance), which are based on Magnetohydrodynamics and Magnetoresistance phenomena. These findings will have significant impacts on processes involving proton and electron transfer as used in Li ion battery, fuel cells, electrochemical and biological sensing, and electrocatalytic CO2 reduction. The perspective for future projects will be discussed as well.
(Invited) Electrochemical Deposition of Carbon Materials in Molten Salts
Authors: Wang Dihua , Gao Muxing , Chen Zhigang , Deng Bowen , Yin Huayi , Xiao Wei , Mao Xuhui
Published: February 2020

Molten salt CO2 capture and electrochemical transformation (MSCC-ET process) into carbon and oxygen [1] is a promising way for effectively capturing and utilizing the greenhouse gas. In the process, CO2 is first absorbed by the molten salt to form carbonate ions and then they are reduced to carbon on the cathode. There are several advantages of the process over others: (1) high current density; (2) high selectivity and current efficiency; (3) lower decomposition potential and overpotential for both anode and cathode reaction; (4) value-added product of functional carbon; (5) simple and cost-affordable electrodes; (6) scalability; (7) environmental friendly and etc. Although electrodeposition of carbon in molten carbonates was first reported in 1960s [2], it is very recent that it becomes a research focus due to the great concern of global warming. There is some new advancement in the field either on the fundamental aspects or practical applications in recent years. Herein, we report the absorption kinetics and thermodynamics of CO2 by molten salt under different temperature and partial pressure of CO2 using a home-made CO2 absorption testing system [3]. The absorption capacity of dissolved Li2O was 0.835 molCO2/molLi2O at 723 K in Li2O containing ternary eutectic carbonate. The mass transfer of carbonates was the dominating factor governing the rate of static absorption. The reduction mechanism of cathode and anode was evaluated by in-situ gas analyzing. There was no CO was detected at 723K over a wide potential range. The reduction kinetics of carbonate was further investigated by cyclic voltammetry and steady-state polarization curve measurements under different temperature and the rate-limiting step was determined. Furthermore, carbon materials with different morphology and composition were obtained under different electrolysis temperature, cell voltage or in different molten salts. It was found that the MSCC-ET process can not only capture CO2 but also absorb SO2 in flue gas. Sulfur doped carbon was obtained by using flue gas as raw material and zero SO2 emission was realized in the process. The obtained carbons show very high specific capacitance and specific capacity as electrode materials for supercapacitor and lithium ion battery, respectively [4].

References:

[1] H.Y. Yin, X.H. Mao, D.Y. Tang, W. Xiao, L.R. Xing, H. Zhu, D.H. Wang, D.R. Sadoway, Energy Environ. Sci., 2013, 6, 1538-1545.

[2] M.D. Ingram, B. Baron, G.J. Janz, Electrochim. Acta, 1966, 11 ,1629-1639.

[3] BW Deng, JJ Tang, XH Mao., YQ Song, H Zhu, W Xiao, and DH Wang, Environ. Sci. Technol., 2016, 50, 10588–10595

[4] JJ Tang, BW Deng, F Xu, W Xiao, DH Wang, Journal of Power Source ，2017，341, 419-426
From Designing and Characterizing Multifunctional Nanoarchitectures to Commercializing Zinc Sponge–Based Alkaline Batteries That Refuse to Launch Dendrites
Authors: Rolison Debra R. , Long Jeffrey W. , Parker Joseph F.
Published: February 2020

Our team at the Naval Research Laboratory looks at rate-critical processes where events per second are required for high performance in such areas as energy storage, energy conversion, (electro)catalysis, and sensing. We then design next-generation systems built around pore–solid nanoarchitectures that seamlessly embody all of the requisite rate functions for high-performance electrochemistry: molecular mass transport, ionic/electronic/thermal conductivity, and electron-transfer kinetics. We have taken the lessons from 20 years of probing the operational and design characteristics of energy-relevant nanoarchitectures to create a zinc sponge—a stand-alone, 3D-wired anode that improves current distribution within the electrode structure during charge–discharge cycling and thwarts dendrite-formation. With this breakthrough, we can now address the family of zinc-based rechargeable alkaline batteries: nickel–3D zinc, silver–3D zinc, MnO2–3D zinc, and even rechargeable 3D zinc–air. The route taken to move from a creative concept to fabricated reality to fundamental characterization to development within a Federal laboratory to commercialization by outside companies will be discussed.
(Invited) Atomic Layer Deposition of Nanoalloys of Noble and Non-Noble Metals
Authors: Ramachandran Ranjith K. , Dendooven Jolien , Filez Matthias , Galvita Vladimir V. , Poelman Hilde , Solano Eduardo , Minjauw Matthias M. , Marin Guy B. , Detavernier Christophe
Published: February 2020

Bimetallic nanoparticles (BMNPs) play a pivotal role in optical, magnetic and electronic applications, and are true workhorses during the catalytic transformation of chemicals. In particular, supported Pt nanoparticles alloyed with In, Ga or Sn are highly selective catalysts for the dehydrogenation of propane to propylene. It is well established that the size and composition of the nanoparticles strongly impact the catalytic properties and performance. Yet, conventional synthesis strategies lack proper control over the nanoparticle morphology and composition. ALD has proven its potential for the size and composition controlled synthesis of supported BMNPs, but has to date only been applied for the synthesis of binary noble metal nanoparticles like Pt-Pd, Pt-Ru and Pd-Ru BMNPs. Extension of this approach to BMNPs containing non-noble metals has so far been hampered by unfavorable ALD chemistries to deposit non-noble metals in their elemental state. As a consequence, a strong need has arisen to develop alternative ALD-strategies which can deal with non-noble metals also.

We report a new ALD based procedure for the tailored synthesis of BMNPs containing a non-noble metal next to a noble metal (ACS Nano, 2016, 10, 8770–8777), here exemplified for nanoalloys containing In as non-noble and Pt as noble metal. Figure 1a schematically describes the steps involved in the fabrication process of the Pt-In BMNPs. Thin layers of In2O3 and Pt are sequentially deposited by ALD, yielding a Pt/In2O3 bilayer structure. These bilayers are then subjected to a temperature programmed reduction (TPR) in hydrogen to induce the formation of Pt-In nanoalloys. The BMNP formation during TPR was followed by in situ XRD measurements (Figure 1b) and was further confirmed by ex situ XAS (Figure 1c) and SEM measurements. The composition of the formed bimetallic alloys can be tuned by controlling the ratio of the deposited thickness of Pt to the thickness of In2O3. Figure 2a presents the relation between the as-deposited Pt/(Pt+In) atomic ratio and the alloy phase(s) obtained after TPR. In addition, our method enables tuning of the particle size with high precision in a range from 1 to 30 nm by changing the total thickness of the ALD-grown Pt/In2O3 bilayer (Figure 2b). Tuning of the particle size while keeping the composition the same can thus be achieved by scaling the layer thicknesses of the Pt and In2O3 layers while keeping the Pt/(Pt+In) atomic ratio constant.

Finally, successful BMNP synthesis was achieved on mesoporous silica, resulting in high surface area nanocatalysts which showed promising high activity for propane dehydrogenation.

Figure 1
(Invited) Nanostructured Thermoelectric Materials Prepared from Bi2Se3 and Bi2Te3 Nanoplates for Enhanced Thermoelectric Properties
Authors: Roh Jong Wook , Hwang Sungwoo , Yang Dae Jin , Tack Han In
Published: February 2020

The development of high-performance thermoelectric (TE) materials has been a challenging issue to realize power generation or eco-friendly refrigerating systems. In particular, TE materials based on the nanomaterials such as nanoparticles, nanowires, and nanoplates have been expected to enhance the TE efficiency. Herein, we introduced the solution-based synthesis of 2D Bismuth chalcogenides with the ultra-thin thickness Bismuth chalcogenides (Bi2Q3, Q = Se, Te), which is known the best TE materials at room temperature, are layer-structured materials arranged in planar quintuple layers (QLs, with each QL approximately 1 nm thick). Each QL consists of five consecutive covalently bound atomic sheets (Q-Bi-Q-Bi-Q), and neighboring QLs are stacked by weak van der Waals interactions along the c-axis. It is well known that introducing nanoscale grains and interfaces in nanostructured bulk composites increases the phonon scattering and filters low energy charge carriers without any considerable reduction in electronic conductivity. This enhanced phonon scattering leads to a higher thermoelectric figure of merit (ZT). One promising approach for achieving uniformly distributed nanoscale interfaces is to use laterally heterostructured nanoplates as building blocks. In this study, thermoelectric properties of pelletized bulk samples was systemically investigated, which are made of the (Bi2Se3)x@(Bi2Te3)1-x