bluuebunny/crossref_metadata_2025 huggingface dataset:
(Keynote) Mechanisms and Selectivity of the Electrochemical CO2 Reduction Reaction on Multiple-Site Versus Single-Site Catalysts
Authors: Strasser Peter
Published: February 2020

Strategies toward closing the anthropogenic carbon cycle using the chemical conversion of CO2 in off-gas streams of steel-mills or cement-plants into useful molecules have become a scientific and technological priority. Of all chemical ways to convert CO2 into hydrocarbons, the direct electrochemical coupling of water electrolysis and CO2 reduction appears attractive, as it is a one-pot process step, occurs at ambient temperature and pressures, involves solely water and CO2 as reactants, and may involve renewable electricity from wind, solar or hydro power plants.

The CO2 electroreduction to gaseous C1 products such as CO or CH4 is often carried out on the surface of metal catalysts such as Cu, Ag or Au. At industrially relevant current densities and electrode potentials, however, these catalysts typically suffer from low faradaic C1 product selectivities due to the competing, very fast reduction of water, i.e. the hydrogen evolution reaction. New catalyst concepts with tunable selectivity for hydrogen evolution versus CO2 reduction are needed(1-3).

In this contribution, we share recent experimental and computational mechanistic studies(4) on the electroreduction of CO2, CO, HCOH on metallic multi-site versus metal/heteroatom-doped carbon single-site catalysts. We provide new insight into CO selectivity trends and put particular emphasis on the competing reaction pathways to methane and methanol. We show that carbon-based single site catalysts are an intriguing cost-effective alternative to metals.

1. H. Mistry, A. S. Varela, S. Kühl, P. Strasser, B. R. Cuenya, Nanostructured electrocatalysts with tunable activity and selectivity. Nature Reviews Materials, 16009 (2016).

2. H. Mistry et al., Highly selective plasma-activated copper catalysts for carbon dioxide reduction to ethylene. Nat Commun, (2016).

3. A. S. Varela et al., Metal-Doped Nitrogenated Carbon as an Efficient Catalyst for Direct CO2 Electroreduction to CO and Hydrocarbons. Angewandte Chemie International Edition
54, 10758-10762 (2015).

4. A. Bagger, W. Ju, A. S. Varela, P. Strasser, J. Rossmeisl, Single site porphyrine-like structures advantages over metals forselective electrochemical CO2reduction. Catal Today, http://dx.doi.org/10.1016/j.cattod.2017.1002.1028 (2017).
(Invited) Electronic-Level Insight on CO2 Reduction Reaction
Authors: Lewera Adam , Gorzkowski Maciej T. , Jurczakowski Rafal Robert , Kulesza Pawel J
Published: February 2020

There is general agreement that catalytic activity is correlated to electronic properties of the catalyst’s surface. For selected molecules and simple surfaces it was shown by Norskov and co-workers that the strength of adsorption of such molecule and the kinetics of the respective catalytic reaction can be correlated to theoretically predicted electronic properties of the surface, i.e. catalyst d-band center (in relation to Fermi edge). However the calculated energy of the d-band center cannot be always correlated to catalytic activity, and the calculated electronic structure (DOS) is not always representative of the experimentally determined electronic structure, especially for non-uniform systems. This is the major drawback of the theoretical approaches currently being used to predict or explain the observed catalytic activity. Thus for assessing the factors responsive for catalytic activity, experimental determination of surface electronic structure is imperative.

X-ray Photoelectron Spectroscopy (XPS) and UV Photoelectron Spectroscopy (UPS) experiments are often used to study the electronic properties of materials. In particular core-level electron’s binding energy and valence band (VB) electron’s density of state can be determined using XPS and UPS. Due to interactions of ejected photoelectrons with matter those experiments are in general limited to the Ultra-High Vacuum (UHV) conditions (ca. 10-9 mbar). In the recent years however the Near Ambient Pressure X-ray Photoelectron Spectroscopy/UV Photoelectron Spectroscopy techniques (NAP XPS/UPS) were developed, allowing for local (at the sample surface) increase in pressure up to tenths of millibars, bridging the gap between UHV adsorption studies and real-life systems. Using of the NAP methods presents unique opportunity to study the electronic properties (and changes of electronic properties) of surface during the adsorption from gas phase. This is of paramount importance as insight can be gained on electron-level interactions between the surface and adsorbing molecule, bond breaking/bond forming and similar phenomena, which was not possible before.

Investigating the electronic properties of catalysts, in particular valence band DOS, in both – Ultra-High Vacuum (UHV) and Near Ambient Pressure (NAP) conditions allows for experimental determination of electronic-level properties of surface in absence and presence of CO2 molecule, the electronic-level changes induced by CO2 adsorption and experimental verification of CO2 adsorption theories. It can be expected that utilizing NAP XPS will results in better understanding of CO2 adsorption processes, fine-tuning the theoretical models and advance the science and technology of catalytic CO2 reduction.
(Invited) Silicon Nanowires Photocathodes Combined with Mn-Based Molecular Complex Catalysts for the Efficient Light-Driven Electrocatalytic Reduction of CO2 to CO
Authors: Fabre Bruno , Chardon Sylvie , Torralba-Penalver Encarnacion
Published: February 2020

Proton-assisted multielectron reduction potentials for CO2 lie within the bandgap of several semiconductors, in such a way that their use as photocathodes for this reaction allows a substantial decrease in the energy input required [1-3].

In the present work, hydrogen-terminated silicon nanowires (SiNWs-H) are used as a photocathode for the electrocatalytic reduction of CO2 in the presence of different metallic bipyridyl complexes. Due to their nanostructured surface, SiNWs are highly interesting as light-harvesting electrodes, being efficient in converting solar to electrical energy, easy to make and stable under reduction conditions [4]. Among the tested complexes, we have used Mn non-noble metal based complexes to catalyze CO2-to-CO photoelectroreduction, which is a less expensive approach versus the traditionally used based on rare and noble metal complexes [5].

The photoelectrochemical reduction of CO2 at p-type SiNWs-H was achieved at potentials significantly lower than those required with a glassy carbon electrode (GCE) and planar Si-H [6]. Thus, for intermediate reduction potentials the photocurrent density values provided by silicon were noticeably higher than the current densities provided by GCE. Besides, impedance spectroscopic measurements were carried out and combined with cyclic voltammetry data to obtain the quantitative complete characterization of the energetics of all the systems studied. All the experiences were carried out at p-type flat silicon for comparison purposes and key electrocatalytic parameters such as fill factor (FF) and energy conversion efficiency (η) were determined.

Finally, in order to develop technologically viable electrocatalytic devices, the elaboration of SiNWs−H photoelectrodes modified with a Mn-based complex has been successfully achieved from an electropolymerizable catalyst, and it was shown that the electrocatalytic activity of the complex was retained after immobilization.

[1] Aresta, M. et al., Chem. Rev. 2014, 114, 1709.

[2] Costentin, C. et al., Chem. Soc. Rev.
2013, 42, 2423.

[3] Schmidt-Mende, L. et al., Angew. Chem. Int. Ed.
2013, 52, 7372.

[4] Wang, D. et al., Angew. Chem. Int. Ed.
2012, 51, 6709.

[5] Kubiak, C. P. et al., J. Phys. Chem. C
2010, 114, 14220.

[6] Torralba-Penalver, E. et al., ACS Catal.
2015, 5, 6138.
(Invited) Carbon Dioxide Electroreduction at Ultrathin Palladium Layers Deposited on Copper Electrode
Authors: Jurczakowski Rafal Robert , Januszewska Aneta , Gorzkowski Maciej Tomasz , Lewera Adam , Kulesza Pawel J
Published: February 2020

Electrochemical conversion of carbon dioxide into eligible fuels has become the subject of particular fundamental interest. Recently, we have reported electrochemical studies on CO2 electroreduction at multilayered catalyst composed of the monatomic layer of copper covering palladium overlayers (0.8-10 monolayers) deposited on the well-defined Au(111) surface [1]. In this study Carbon dioxide electroreduction has been studied at ultrathin palladium layers deposited on copper electrode. The Pd deposits have been prepared by using chemical methods. The spontaneous galvanic displacement and resulting uncontrolled deposition of the palladium on copper has been entirely eliminated by the use of palladium(II). This method allowed us for controlled and precise deposition of palladium layers by electrochemical methods. The deposits coverage was changed within the range 0.5 to 5 atomic monolayers. The effectiveness of the method and the durability of the obtained ultrathin palladium layers have been confirmed by X-ray photoelectron spectroscopy (XPS). XPS has been also used for detailed analysis of the electronic properties of the Pd/Cu systems. Significant chemical interactions of both elements resulted in a partial shift of the electron density from palladium to copper and in the changes in the symmetry of 3d palladium signals characteristic for two-dimensional palladium structures (Pd monolayers). A detailed analysis of the valence band structure of Pd/Cu was correlated to the catalytic activity of the studied systems. The unique properties of the valence band structure cannot be attributed to the simple superposition of pure metal bands (Pd and Cu). It has been shown that the increase in the electron density near the Fermi level results in a significant decrease in the overpotential of the carbon dioxide electroreduction. Analysis of the gaseous products obtained in the CO2 electroreduction was performed by gas chromatography. Adsorption of carbon dioxide on Pd/Cu layers was demonstrated by XPS measurements in the presence of 1 mbar CO2 in XPS measurements under near ambient pressure XPS (NAP-XPS).

[1] A. Januszewska, R. Jurczakowski, P. Kulesza, Langmuir 30(2014)14314-14321
A Comparison of Aqueous CO2 Reduction on Ni-Ga Thin Films and Nanoparticles
Authors: Francis Sonja A , Chu An T , Torelli Daniel A , Crompton J Chance , Lewis Nathan S , Bocarsly Andrew B.
Published: February 2020

It was recently reported that thin films of nickel-gallium, prepared simply by drop-casting aqueous salt solutions onto graphite plates, were active for carbon dioxide reduction in aqueous carbonate electrolytes acidified to pH 6.8 with 1 atm CO2. The Ni-Ga thin films produce mixtures of methane, ethylene and ethane at potentials as anodic as -0.48V vs RHE, representing some of the lowest onset potentials for C2-product formation reported to date. While polycrystalline Cu also produces CH4 and C2H4, the onset potential for these products on Ni-Ga films is several hundred millivolts more positive. However, the current densities on Ni-Ga are ~ 3 orders of magnitude lower than Cu. One strategy to improve the current densities is the use of nanostructured Ni-Ga catalysts. Thus, we present a novel synthesis of Ni-Ga nanoparticles for the purpose of probing their carbon dioxide reduction behavior. Micrometer sized clusters of Ni3Ga nanoparticles (~8-13 nm in diameter) were synthesized from the reflux of Ni(COD)2 and Ga(acac)3 salts in 1-octadecene solvent at 310°C (COD = cyclooctadiene, acac = acetylacetonate). The nanoparticles were supported on carbon black (Vulcan XC-72) and fabricated onto a glassy carbon electrode with ionomer solution. Interestingly, in aqueous K2SO4 electrolyte saturated with 1 atm CO2 (pH 4.38), the Ni-Ga nanoparticles reduced CO2 to formic acid with Faradaic efficiencies as high as 36% at -0.92 V vs RHE. This contrasting activity to Ni-Ga thin films is discussed with an emphasis on the effect of composition, surface structure, and support of the catalyst. 

Figure 1
In-Situ infrared Spectroscopic Investigations of Pyridine-Mediated CO2 Reduction on Pt Electrocatalysts
Authors: Dunwell Marco , Yan Yushan , Xu Bingjun
Published: February 2020

The pyridine-mediated electrochemical reduction of CO2 ­to methanol, formate, and formaldehyde was first demonstrated by Bocarsly et. al in 1994. Since then, many mechanistic investigations of this process have been conducted using reactivity measurements, cyclic voltammetry, or computational methods; however, direct experimental mechanistic investigation has been lacking. We employ surface-enhanced infrared absorption spectroscopy, coupled with traditional electrochemical techniques to probe the electrochemical interface during the pyridine-mediated electrochemical reduction of CO2 on Pt electrocatalysts. Previously proposed mechanisms are discussed and refined in light of new insights obtained in this study.
(Invited) The Role of Interfacial Potentials in Fundamental Studies of Ion Solvation
Authors: Beck Thomas , Pollard Travis
Published: February 2020

Establishing a single-ion free energy scale has been a long sought goal in electrochemistry. Besides the fundamental importance of this problem, its resolution impacts diverse areas such as ion density profiles near interfaces and force field development. While there is no unique way to disentangle the the chemical and electrostatic portions of the electrochemical potential, we discuss recent work aimed at a physically motivated separation. The resulting surface potential is an average potential that can influence ion distributions near interfaces. While this does not influence the equilibrium thermodynamics of a galvanic cell, the resulting distributions may affect the kinetics. This talk will summarize recent work in this area, including discussion of ions in water and in organic solvents such as ethylene carbonate and propylene carbonate. Classical and quantum simulations of ions in the organic solvents illustrate the importance of polarization for accurate modeling of solvation thermodynamics.
(Invited) Macroscopic Models of Ion-Nafion Interations: Influence of Counter Ion Density on Network Morphology
Authors: Promislow Keith , Wetton Brian
Published: February 2020

We develop a continuum energy formulation for an ionomer membrane with a multicomponent counter-ion electrolye, such as occur in Vanadium redox flow batteries. At low hydration levels the high electrolyte molarity induces strong interactions between tethered and counter ions, as well as competition for solvation among ionic groups. Through-membrane variation in composition of the counter-ion density can lead to changes in the ionomer membrane network morphology, which in turn couple to the counter ion mobility. We consider a gradient flow model which couples electrolyte motion, solvation, ionomer network morphology and present both analytical and numerical simulations.
Modeling the in Situ Ionic and Electronic Conductivity of the Porous Electrodes Linked to the Oxidation-Reduction Reactions in Solid Oxide Fuel Cells
Authors: Cheng Tian-Le , Lei Yinkai , Wen You-Hai
Published: February 2020

The ionic conductivity is essential to the performance of a solid oxide fuel cell (SOFC). While the effective conductivity of a porous electrode is frequently involved in SOFC models, the concept of the real (in situ) conductivity in a working electrode is yet to be clarified. To model the in situ ionic and electronic conductivity, the microstructure/geometry and the associated spatial property distribution, as well as the chemical reactions have to be explicitly considered. Here we present a theoretical framework together with phase field modeling to approach this issue. In addition, a recently developed spectral method is used to solve the transport problem in media with complex microstructure.
Reactive Molecular Dynamics Modeling of Iron Passivity
Authors: DorMohammad Hossein , Pang Qin , Árnadóttir Líney , Isgor O. Burkan
Published: February 2020

Passivity of iron in a highly alkaline environment is investigated using Reactive Force Field Molecular Dynamics (ReaxFF-MD). Simulations were performed on the Fe(110) surface that is exposed to a NaOH solution (pH=13.5) that is assumed to simulate the highly alkaline environments in concrete pore solutions. Helmholtz, Gouy-Chapman and Stern models for electrical double layer were compared in terms of their applicability in studying passivity. It was shown that only the Stern model was able to capture the expected thermodynamic passivation behavior of iron in the alkaline media. Additional ReaxFF-MD simulations with the Stern model showed that passivation process involved dissociation of NaOH to charged Na+ and OH- ions; dissociation of water into charged OH-, H3O+, O2-, and H+ species; formation of a charged layer of iron atoms at the metal-electrolyte interface; and the diffusion of oxygen into the iron bulk to form passive iron oxides. A control study was also conducted to investigate the capability of Stern model for simulating metal/electrolyte interface in a NaCl solution representing neutral conditions (pH≈7) that is expected to cause active corrosion. These simulations supported the expected corrosion behavior.
An Open-Source Data Science Platform for the Electrochemical Community
Authors: Masse Robert
Published: February 2020

It is no exaggeration to say that the lithium-ion battery has revolutionized the world, and the importance of electrochemistry has been brought to the fore as we look to improve batteries for electric vehicles, biomedical devices, and other critical applications.

However, electrochemical studies – particularly on batteries – are conducted with software tools that were not designed for the scale and the importance of the energy storage industry today. The software provided by hardware vendors often does not readily provide the answers we need, or even allow us to ask the right questions. Legacy software tools are often no better and suffer from severe stability issues. In industry, time is critical and most data goes unanalyzed, putting manufacturers at risk. Other firms build in-house tools that constantly reinvent the wheel.

We believe the community would be better served by working together with tools commensurate with the tasks we face. In recent years, several open-source software and hardware tools have been developed by the electrochemical community. However, most have only garnered modest traction. We believe this is driven by the high barrier of adoption, since most electrochemists are not also software developers, and because a significant amount of time and resources must be dedicated to supporting such projects.

Here we present an open-source web-based tool that lays the foundation for collaboration, and addresses the issues described above. Our platform is designed to accomplish the following:

1) Automate rote data analysis. Hours of analysis can be done in minutes or seconds to generate standard plots and statistics for cell capacity, voltage profiles, and cyclic voltammetry, as well as more involved analyses like incremental capacity or other user-defined functions. This is particularly important for batteries where both the number of electrochemical cells and cycles per cell may be very large and cumbersome to analyze thoroughly.

2) Reduce the barrier to enter and contribute to the platform. We provide APIs for a common framework for others to build upon. This saves time compared to developing a one-off application from scratch, and allows for greater impact when packaged together with a suite of other tools.

3) Catalyze electrochemical data science. The growing field of the data science allows for new tools to be developed to ask new questions and glean previously invisible insights from battery performance data.

We believe this software platform provides the missing infrastructure required to meet the demands of the electrochemical community today, and rise to the challenges of tomorrow.
Phase-Field Modeling of the Thermal Growth of an Oxide Film and the Electrochemical Performance of a Solid Oxide Fuel Cell: Similarities and Differences
Authors: Cheng Tian-Le , Wen You-Hai , Hawk Jeffrey A.
Published: February 2020

The thermal growth of oxide film on top of a metal surface can be viewed as an electrochemical process and unless at very thin-film stage, the growth kinetics is largely controlled by mass transport (ionic) across the oxide layer. The latter process is also essential to solid oxide fuel cells (SOFCs). Differences are that for the former, the ionic transport is the slower the better for the sake of oxidation resistance, while for the latter, the faster the better in terms of cell performance. From the modeling perspective, both the processes involve a concern regarding the characteristic length scale that is the Debye length. We present an electrochemical phase-field model for thermal oxidation together with a multi-scale scheme which continuously models oxide film growth across orders of magnitude in length around the Debye length. On the other hand, phase-field modeling regarding SOFCs is approached at two length scales at and above the Debye-length scale. Issues in oxidation modeling especially the coupled-currents condition and local equilibrium, and their counterparts in SOFC modeling will be discussed.
Exceptional Energy and New Insight with Sodium – Selenium Battery Based on Carbon Nanosheet Cathode and Pseudographite Anode
Authors: Mitlin David
Published: February 2020

We created a unique sodium ion battery (NIB, SIB) cathode based on selenium in cellulose-derived carbon nanosheets (CCN), termed Se-CCN. The elastically compliant two-dimensional CCN host incorporates a high mass loading of amorphous Se (53wt.%), which is primarily impregnated into the 1 cm3g-1 of the nanopores. This results in facile sodiation kinetics due to short solid-state diffusion distances and large charge transfer area of the nanosheets. The architecture also leads to an intrinsic resistance to polyselenide shuttle and to disintegration/coarsening. As a Na half-cell, the Se-CCN cathode delivers a reversible capacity of 613 mAh g-1 with 88% retention over 500 cycles. The exceptional stability is achieved employing a standard electrolyte (1M NaClO4 EC-DMC), without secondary additives or high salt concentrations. The rate capability is also superb, achieving 300 mAhg-1 at 10C. Compared to recent state-of-the-art literature, the Se-CCN is the most cyclically stable and offers the highest rate performance. As a Se-Na battery, the system achieves 992 Wh/kg at 68 W/kg and 384 Wh/kg at 10144 W/kg (by active mass in cathode). We are the first to fabricate and test a Se-based full NIB, which is based on Se-CCN coupled to a Na intercalating pseudographitic carbon anode (PGC). It is demonstrated that the PGC anode increases its structural order in addition to dilating as a result of Na intercalation at voltages below 0.2 V vs. Na/Na+. The {110} Na reflections are distinctly absent from the XRD patterns of PGC sodiated down to 0.001 V, indicating that Na metal pore filling is not significant for pseudographitic carbons. The battery delivers highly promising Ragone chart characteristics, for example yielding 203 and 50 Wh kg-1 at 70 and 14000 W kg-1 (by total material mass in anode and cathode).
Development of Novel Electrode Using Nickel-Based Film with Bi2-XRu2O7-Z Nano-Particles on Resin for Air Secondary Battery
Authors: Tamura Yuichiro , Kawaguchi Kenji , Hirose Yutaka , Nishiyama Hiroshi , Nakanishi Shinji , Iba Hideki , Morimitsu Masatsugu
Published: February 2020

An air secondary battery has a gas diffusion electrode as the positive electrode, so that the battery has no need to store the active mass in the electrode and the capacity of the positive electrode is not limited. This also means that the weight of the air electrode can be reduced and is independent of the battery capacity. For this purpose, we have been developing the air electrode’s material which consists of nickel-based film co-deposited with pyrochlore-type oxide on resin by electroless nickel plating [1]. In this work, we present a novel preparation method to obtain the nickel-based film which contains Bi2-xRu2O7-z nano-particles in the outermost surface on resin and the results of the polarization measurements for oxygen reduction and evolution in KOH solutions.

The precipitate obtained from the metal salt solution containing Bi(III) and Ru(III) after adding NaOH solution was calcined to obtain Bi2-xRu2O7-z nano-particles, which were added into the electroless nickel plating solution. The oxide particles on the outermost surface of the nickel-based film formed on ABS resin were obtained by electroless nickel plating with using the rotating disk electrode (RDE). The obtained sample was analyzed by SEM and EDX and used as the rotating disk electrode in a three-electrode cell to measure the polarization behaviors for oxygen reduction and evolution in 0.1 mol/L KOH solutions.

The SEM and EDX results revealed that more Bi2-xRu2O7-z particles were deposited on the outermost surface of the nickel-based film formed on ABS resin than those in our previous work [1], although the oxide particles seemed to be aggregated. This surface modified resin electrode was set as the RDE in KOH solution, and cyclic voltammetry was carried out for ORR and OER, in which the measurement for oxygen reduction was performed with the solutions under O2 or N2 atmosphere and the net current was obtained by subtracting the current in N2 from that in O2. The results indicated that the oxygen reduction and evolution on the electrode were observed and the current density for both reactions was higher than that obtained in our previous work [1], because more oxide catalysts were contained in the nickel-based film and were seen on the outermost surface, resulting in the increase in surface area. The results also indicated a possibility of a light air electrode based on 3D-structured resin of which the surface is modified with a conductive nickel-based film containing a bi-functional oxide catalyst such as bismuth ruthenium oxide. More detailed results will be shown in this paper.

Reference

[1]Y. Tamura, M. Morimitsu, PRiME 2016, Abs#0787, Honolulu (2016).
Performance Test and Examination Technologies of High Energy Solid-State Lithium Ion Batteries (SSLIB)
Authors: Chao Chung-Hsiang , Chang Chih-Ching , Wu Wei-Hsin , Jin Yi-Chun , Wu Sheng-Hui , Lee Jen-Jeh , Fang Jason
Published: February 2020

Nowadays, the international battery manufactories plan to mass produce high energy-storage products with 300Wh/kg or higher in 2020-2030 to double EV cars traveling distance. However, this will not be immediately effective meet the huge demands used in transporting vehicles. To connect this technical gap, we challenge high energy SSLIB (350Wh/kg) with following strategies: (1) Nickel-rich high working-voltage (>3.9V) cathode material with core-shell structure. (2) Lithium metal/ alloy anode with buffer layer and special morphology. (3) Nano-composited solid state electrolyte with inorganic oxide compound Li+ superconductor. (Total conductivity= 2*10-4S/cm @ rt.)

Another part of this poster, we apply different temperature, voltage and current density limit to maximize the efficacy of SSLIB. Meanwhile, we force the battery to fail. To the best of our knowledge, there are limited literatures discussing about SSLIB failure mode. With in-situ micro- and macroscopic examination, we can exam SSLIB failure mechanism. With comparison of computerial simulation, we try to define SSLIB failure mode and establish SSLIB safety testing standards.

Figure 1
Enhanced Optical Coated Witness Plates for the in Situ Monitoring of Spacecraft Health
Authors: Rutherford Gugu N , Seasly Elaine E , Thornblom Mark N , Cashwell Irving , Bahoura Messaoud
Published: February 2020

In the field of aerospace, contamination control is an engineering field that develops a strategy to mitigate molecular and particulate contamination effects on spacecraft performance. Molecular contamination is known as the hidden risk that interferes with the performance of optical, thermal, electronic, and mechanical systems. Traditional methods for monitoring spacecraft health involves the use of rinsate from a witness surface to collect molecular films known as non-volatile residues (NVR). In order to identify a chemical fingerprint of potential harmful contaminants, Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS) are tools for characterizing the NVR. Unfortunately, these passive characterization tools limit the ability to find problematic NVR during the early phases of the assembly of space flight hardware. A common method is the optical witness plate program that uses FTIR to monitor the collection of NVR within a 28 day period. The witness plate program has a limit of detection within several microns of NVR. Often nanometer thick molecular films can interfere with sensitive surfaces. In this work, we evaluate the use of enhanced optical coatings deposited onto witness surfaces as a practical sensing application to monitor the health of spacecraft. This method has the potential to enable in situ monitoring of spacecraft by utilizing the enhanced optical coated surfaces coupled with a portable Raman Spectrometer during the assembly, integration, and test phases to qualitatively identify egregious contaminants that may adversely impact spacecraft system cost and schedule.
Long Term Performance of Amperometric Gas Sensors Outside the Lab
Authors: Carter Michael T , Findlay Melvin W , Stetter Joseph R , Ploense Lloyd , Meulendyk Bennett J. , Patel Vinay , O'Toole Gavin , Escobar William
Published: February 2020

One major R&D effort at KWJ Engineering over the past 2 years has involved new amperometric gas sensors with ionic liquid electrolytes as alternatives to standard aqueous acid electrolytes. Part of this effort involves long term testing and validation of sensor performance (sensitivity, baseline drift, chemical interferences and stability under variable environmental conditions) compared to reference sensors. This presentation will discuss evaluation of sensor performance and the development of performance specifications for these sensors as part of the product development effort.
Free the Science Overview and Update
Authors: Taylor E. J
Published: February 2020

ECS Treasurer and Free the Science Advisory Board co-chair discusses the ECS initiative to implement open access and accelerate findings through open science.
(Invited) Real-Time Striatal Measurements of Oxidative Stress and Dopamine in the Dyskinetic Rat during Chronic L-DOPA Treatment for Parkinson’s Disease
Authors: Sombers Leslie A , Wilson Leslie R. , Mason Catherine F. , Lee Christie A
Published: February 2020

Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by the preferential loss of dopaminergic neurons stemming from the substantia nigra pars compacta and innervating the dorsal striatum. The substantial decreases in striatal dopamine (DA) result in devastating hypokinetic movements and motor disturbances. Increased generation of reactive oxygen species, such as hydrogen peroxide (H2O2), is also thought to contribute to Parkinsonian symptoms. However, the precise role of H2O2 in the initiation, progression, and maintenance of the disease remains unclear, as reactive oxygen species are difficult to monitor in brain tissue. Further, several lines of evidence suggest that the standard treatment strategy of dopaminergic replacement therapy via administration of Levodopa (L-DOPA; L-3,4 dihydroxyphenylalanine) may serve to increase oxidative stress and potentiate cell death. We are investigating how striatal H2O2 and DA dynamics underlie behavioral changes that result from chronic L-DOPA administration in a rodent model of PD (unilateral 6-OHDA lesion) using fast-scan cyclic voltammetry, an electrochemical technique that affords precise spatial and temporal resolution, as well as selective detection of these neurochemicals. Specifically, carbon-fiber microelectrodes are used to simultaneously quantify rapid H2O2 and DA fluctuations at single recording sites in the dorsal striatum over several weeks of L-DOPA administration. The chemical fluctuations are correlated with behavioral abnormalities that develop over the course of treatment. These studies are advancing our understanding of how oxidative stress modulates nigrostriatal DA signaling, and are demonstrating how these signals correspond with dyskinetic movements in the treatment of PD.
(Invited) Fast Scan Cyclic Voltammetry for Probing Depression and Developmental Disorders
Authors: Hashemi Parastoo
Published: February 2020

Dysfunctions of the brain’s serotonin system are thought to underlie the symptoms of depression and autism spectrum disorder (ASD); the former is thought to be underpinned by a decrease in serotonin signaling and the latter an increase. However, because the roles of serotonin in the brain during health and disease are ill defined, it is extremely challenging to investigate these hypotheses with an eye towards therapies. This situation is confounded because current therapies assume that the serotonin system dysfunctions in the same way regardless of the multitude of causes (psychological, genetic, exposure, disease) of human disease. In this work, we develop and utilize novel voltammetric tools and combine them with mathematical models and confocal imaging to characterize serotonin neurotransmission in different animal models of depression and ASD. We find characteristic chemical serotonin phenotypes that underlie the two disorders. We model the experimental data and offer mechanistic insights into how different extracellular mechanisms that regulate serotonin circumstantially dysfunction. These insights lead us to suggest novel treatment strategies.
(Invited) Electrochemical Characteristics of Diamond Films for Neural Devices
Authors: Martin H.
Published: February 2020

Robust electrode technology is essential to address the growing demand for neural devices for sensing and stimulation in the central and peripheral nervous system. Difficulties remain in device performance, mechanical integrity and stability. Conductive diamond is highly promising to overcome these obstacles, and provides the opportunity to integrate sensing and stimulation in the same robust device. This presentation focuses on our diamond-film electrode development and application for neurosensing and for stimulation of neural activity. Unique fabrication and materials integration approaches have been used to obtain diamond electrodes in a flexible construct; one example is diamond-on-polymer electrode arrays.
(Invited) Novel Carbon-Based Sensors for the Next Generation of Neurochemical Measurements
Authors: Sombers Leslie A , McCarty Gregory S , Roberts James G , Dunaway Lars E , Calhoun Sarah E , Meunier Carl J , Mitchell Edwin C
Published: February 2020

Carbon-fiber microelectrodes have been the fundamental tool for the electrochemical detection of neurotransmitters since their introduction in the early 1980s. They are biologically compatible and, compared to larger electrodes, microelectrodes offer highly increased diffusional flux to the electrode surface and faster response times to enable high speed measurements. The demonstrated benefit of enhanced mass transport to very small electrodes has led us to develop several new carbon-based microelectrodes for the improved detection of dynamic neurochemical fluctuations. This talk will describe the characterization of a recessed microdisk electrode for enhanced detection of individual exocytosis events at single cells, a nanoscale microelectrode with a conical geometry for fast intracellular voltammetric measurements, and innovative yarn-like sensing substrates engineered entirely of multi-walled carbon nanotubes for enhanced sensitivity when monitoring from individual cells or discrete brain regions. Each of these ultramicroelectrode designs exploits mass transport to either provide maximal diffusional flux to, or to limit diffusional flux from, the electrode surface. These new tools provide significant advantages when coupled with fast-scan cyclic voltammetry, and applications that provide new insight into neurochemical dynamics will be discussed.
Atmospheric Plasma-Sprayed La0.3Sr0.7TiO3
-
δ Interconnect for High-Temperature Solid Oxide Fuel Cells
Authors: Chen Xu , Zhang Shan-Lin , Li Cheng-Xin , Yang Guan-Jun , Li Chang-Jiu
Published: February 2020

Lanthanum-doped strontium titanate (La0.3Sr0.7TiO3
-
δ, LST) perovskite is regarded as a promising candidate for high-temperature solid oxide fuel cells (HT-SOFCs) interconnect material due to its good phase stability, good thermal expansion matching to other components, as well as high electrical conductivity in reducing atmosphere. Atmospheric plasma spraying (APS) is a cost-effective processing method to fabricate membranes in SOFCs. However, the LST coatings deposited following the conventional routine exhibit a typical lamellar structure with a limited interlamellar bonding, which dominates the properties of interconnect including gas tightness and electrical conductivity. Besides, the preferential evaporation of Sr during plasma spraying may degrade the performance of LST coatings as interconnect for HT-SOFCs. In this paper, dense LST membranes were deposited on YSZ substrates at preheated conditions by APS. The effect of particle size of LST powders on the chemical composition, phase composition, and electrical conductivity of LST coatings were studied. It was found that the columnar grain growth across lamellar interfaces in LST coatings at the deposition temperature of ~500 °C was highly enhanced with increased interlamellar bonding ratio. Moreover, when the LST particle size is <30 μm, the evaporation of Sr increased remarkably with the decreasing of particle size. When the the LST particle size is ＞30 μm, the evaporation loss of Sr in LST coatings was greatly reduced. A vortex convection model of LST droplets during the spraying process was built to explain the effect of particle size on Sr evaporation. The electrical conductivity and stability of the LST interconnects were tested at controlled atmospheres at an operating temperature of 850 °C. The results show that the electrical conductivity of dense LST coatings prepared with large particles was greatly improved. The LST coatings exhibited excellent phase stability in both reducing and oxidizing atmospheres. Results suggest that LST interconnect with high performance can be deposited by APS through optimizing the microstructure and controlling the chemical composition.
Degradation Analysis of SOFC Stack Performance: Investigation of Cathode Sulfur Poisoning Due to Contamination in Air
Authors: Yoshikawa Masahiro , Yamamoto Tohru , Yasumoto Kenji , Mugikura Yoshihiro
Published: February 2020

Central Research Institute of Electric power Industry (CRIEPI) has operated seven types of SOFC stacks, which are developed by MITSUBISHI HITACHI POWER SYSTEMS (MHPS), KYOCERA, TOTO, NGK SPARK PLUG (NTK), NGK INSULATORS (NGK), MURATA Manufacturing (Murata), and Denso in order to investigate their durability and find dominant degradation factor for each SOFC stacks under NEDO’s project. In the first half of period, remarkable feature of durability tests was large cathode degradation in KYOCERA’s, NGK’s, and Murata’s cells which were examined at CRIEPI site. Because sulfur was detected on their cathodes from post analyses done by AIST with SIMS, in the last half of period, these stacks were reexamined by adopting sophisticated chemical filter for SO2 removal. Results become more acceptable. On the other hands, SO2 concentration in air at CRIEPI site was less than 3 ppbv. The amount of sulfur detected on cathode is significantly larger than that of calculated sulfur from supplied air, another sulfur sources might be considered.
System Approach of a Pressurized High-Temperature Electrolysis
Authors: Brabandt Joerg , Posdziech Oliver
Published: February 2020

Electrolysis is a well-known process to split water (H2O) into hydrogen (H2) and oxygen (O2) by using electrical energy. If the water can be converted into steam by waste heat from other processes or steam is directly available at an industrial facility, it is more efficient to perform a high temperature electrolysis (HTE) and convert the steam directly. Steam is commonly supplied at elevated pressure, and the industrial demand for hydrogen product gas is at high pressure too. Therefore, the overall process efficiency can be increased by operating the HTE at elevated pressure level because steps of expansion and compression of the involved gases are saved. As technique for HTE, solid oxide cells (SOC) are used. So far they are mainly known and used as fuel cells (SOFC). SOC are usually made of different ceramics. They consist of a membrane for gas separation, a hydrogen electrode and an oxygen electrode. The SOC is easy scalable. So called Stacks are a series connection of multiple cells, and these Stacks can as well be connected in series or in parallel to fulfill the requirements of the specific application.

Sunfire presents a system approach for a pressurized SOC system. It is shown how Stacks and Hot-BoP components can be operated at elevated pressures. First results of a prototype with a nominal electrolysis DC input power of 10 kW and an operation range of up to 15 bar are shown. Main objectives are the control of the different pressure sections, stack performance and thermal behaviour at varying pressure levels.

Acknowledgement

The research leading to these results has received funding from the EU’s Seventh Framework Programme for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement n°621210 for the HELMETH project (www.helmeth.eu).

Figure 1
Distribution of Relaxation Times Analysis for Optimization of Anode Thickness in Metal-Supported Microtubular Solid Oxide Fuel Cells
Authors: Sumi Hirofumi , Shimada Hiroyuki , Yamaguchi Yuki , Yamaguchi Toshiaki
Published: February 2020

An anode functional layer (AFL) is inserted between anode substrate and electrolyte thin-film to increase the triple phase boundary (TPB) for anode-supported solid oxide fuel cells (SOFCs). On the other hand, better mechanical robustness, redox tolerance, rapid thermal cycling and cost reduction are expected for metal-supported SOFCs. The anode thickness of metal-supported cells (MSCs) is more important than the AFL thickness of anode-supported cells (ASCs), since the metallic substrate does not have TPB. In the present work, the metal-supported microtubular SOFCs with La0.6Sr0.4Co0.2Fe0.8O3(LSCF)-(Ce0.9Gd0.1)O1.95(GDC) cathode, GDC electrolyte, BaCe0.8Y0.2O3-
d (BCY) blocking layer and Ni-GDC anode on Ni substrate were investigated. The significant decrease in polarization resistance with increasing the anode thickness from 10 to 16 mm was confirmed by the distribution of relaxation times (DRT) analysis for the metal-supported microtubular SOFCs operated at 550 oC.
Analyzing the Mechanical Performance of Solid Oxide Fuel Cells at Interfacial Anode/Electrolyte Regions Using Sub-Micron Resolution 3D X-Ray Computed Tomography
Authors: Heenan Thomas M. M. , Robinson James B. , Lu Xuekun , Bailey Josh J , Brett Daniel J.L. , Shearing Paul R.
Published: February 2020

The use of composite Ni-YSZ cermets is now commonplace, the addition of electrolyte ceramic to the electrode is observed to cause non-linear strain when outside of isothermal environments [1], thought to be maximised at the material interfaces [2, 3].

X-ray tomography has proven to be a powerful tool in the characterisation of electrochemical devices, particularly, when inspecting the structural alterations caused by degradation mechanisms [4]. Additionally, in combination with techniques such as digital volume correlation (DVC), strain and material displacement can be mapped in three dimensions with trajectory information [5], improving understanding of material migration under operationally relevant conditions.

This work presents the microstructural developments at interfacial regions within a solid oxide half-cell exposed to varying degrees of thermal shock, similar to that which would be expected in operational conditions. The microstructure is analysed with use of lab-based X-ray tomography achieving statistically relevant data with sub-micron resolutions while preserving macroscopic mechanical influence via large sample volumes, ca. 5 x107 μm3. By imaging the same volume sequentially using the authors were able to correlate the structural dynamics within the volume using computational DVC analysis.

Figure 1 presents the change in electrolyte angle of an anode supported solid oxide-half cell through increased thermal shock. Various degrees of thermal ramp-rate are examined via X-ray tomography slices and phase percolation network lengths. Decreased connectivity in the electrochemical activity maps within the anode is observed with the increasing electrolyte bowing, resulting in a reduction in the percolated triple phase boundary (TPB) reaction site density. The results here present enhance insight into the real-world mechanical influence of expansion gradients between neighbouring layers during operational thermal cycling.

Robinson, J.B., et al., 2015. Journal of Power Sources, 288, pp.473-481.

Clague, R., et al., 2011. Journal of Power Sources, 196(21), pp. 9018-9021.

Celik, S., et al., 2014. International Journal of Hydrogen Energy, 39(33), pp.19119-19131.

Shearing, P.R., et al., 2012. Solid State Ionics, 216, pp.69-72.

Finegan, D.P., et al., 2015. Advanced Science.

Figure 1

Electrolyte bowing observed in an anode supported Ni-YSZ/YSZ solid oxide half-cell captured using X-ray computed tomography: a) profiles for the four thermal cycles at successively increasing ramp rates of 3, 10, 20 and 30 ᴼC/min, with accompanying single tomograph slices from the b) pre and ci) post-cycling tomograms, cii) magnified electrolyte bowing from the post-cycling tomogram, and d) Ni percolation mapping where white and red paths represent segments longer and shorter than 10 μm respectively.

Figure 1
Development of High Efficiency Steel Cell Technology for Multiple Applications
Authors: Leah Robert Timothy , Bone Adam , Hammer Eva , Selcuk Ahmet , Rahman Mahfujur , Clare Andrew , Rees Lee , Lawrence Nick , Ballard Andrew , Domanski Tomasz , Mukerjee Subhasish , Selby Mark
Published: February 2020

Ceres Power’s unique SteelCell low temperature metal-supported SOFC technology has demonstrated best-in-class robustness to cyclic operation, along with efficiency comparable with more conventional SOFC technology, and intrinsically low cost at the 1kWe scale.

There is also considerable work being undertaken to develop SteelCell technology to be used for higher power applications. Multiple development streams are being pursued to achieve the objectives of high efficiency (60%) and long life needed for prime power applications. This paper will discuss the progress being made to demonstrate the improvements to the fuel cell design to enhance efficiency, life, volumetric power density and fuel utilisation consistent with the requirements of larger power generation units.