bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Graphene Plane Electrode for Low Power 3D Resistive Random Access Memory
Authors: Lee Seunghyun , Sohn Joon , Jiang Zizhen , Chen Hong-Yu , Wong H. -S. Philip 
Published: February 2020

The central theme of the “Internet of Things” is a societal and technological movement towards ubiquitous, abundant-data computing. Such transformation requires real-time analytics on enormous quantities of data collected by a vast network of sensors and other autonomous sources feeding into the data cloud. Current computing technology, however, cannot satisfy such applications with the required throughput and necessary energy efficiency. The next technology frontier will be monolithically integrated chips with 3-dimensionally interleaved memory and logic for unprecedented data bandwidth with reduced energy consumption. In this work, we exploit the atomically thin nature of the graphene plane to assemble a resistive memory stacked in a vertical 3D structure. Compared to the same architecture that uses conventional metal (Pt) as an RRAM electrode, the atomically thin graphene edge electrode was able to reduce power consumption by ×300 while producing a highly localized electrical field for oxygen anion migration. The switching energy of this device is one of the lowest reported compared to existing alternative memory technologies. Importantly, circuit analysis of the 3D architecture using experimentally measured device properties show higher storage potential for graphene devices compared that of metal based devices.
Tellurium Nanowire Arrays-Based Nanogenerators for Thermal Energy Harvesting
Authors: Li Ying-Chun , Lin Zong-Hong 
Published: February 2020

Semiconductor nanorods and nanowires are interesting nanomaterials and have been applied in sensor and energy applications. Tellurium is a typical p-type semiconductor having bandgap energy of 0.35 eV and has already been recognized as an interesting material for fabricating nanodevices. For examples, tellurium nanowires have shown great potential in the applications of nanogenerators, supercapacitor, lithium battery, and biosensors. In this paper, we developed a thin, light-weight, and flexible thermoelectric nanogenerator based on the nanocomposite of tellurium nanowire arrays and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The Seebeck coefficient of the nanocomposite was determined to be 235 μV/K. A linear relationship between the output voltage and the temperature difference across the thermoelectric nanogenerator was observed. We demonstrated that the thermoelectric nanogenerator can be integrated with fiber fabric and harvested the thermal energy from human body temperature. Not only for the purpose of energy harvesting, the thermoelectric nanogenerator can also function as a self-powered sensor for water temperature measurement.
(Invited) Graphene Plasmonics: Plasmon-Plasmon Hybridization and Chemical Sensing
Authors: Farmer Damon , Avouris Phaedon , Han Shu-Jen 
Published: February 2020

Graphene has emerged as an interesting material for plasmonic applications in the terahertz to mid-infrared, the spectral region where its plasmonic resonance typically resides. The coupling behavior of graphene plasmons with both molecular vibrations and other plasmons will be presented. Plasmon energy dispersion with the number of stacked graphene layers allows for the creation of multi-mode plasmonic structures, where unconventional plasmon-plasmon hybridizations arise, resulting in an increased infrared absorption bandwidth. Interaction of graphene plasmons with molecular vibrations results in electromagnetically induced transparency phenomena in plasmon light absorption, thereby increasing the effective infrared absorption cross section of the molecular vibrations. As both bandwidth enhancement and detection sensitivity enhancement have practical value, potential technological implications of these results will also be discussed.
(Invited) Synthesis and Applications of Novel Two-Dimensional Nanomaterials
Authors: Zhang Hua 
Published: February 2020

In this talk, I will summarize the recent research on synthesis, characterization and applications of two-dimensional nanomaterials in my group. I will introduce the synthesis and characterization of novel low-dimensional nanomaterials, such as graphene-based composites including the first-time synthesized hexagonal-close packed (hcp) Au nanosheets (AuSSs) on graphene oxide, surface-induced phase transformation of AuSSs from hcp to face-centered cubic (fcc) structures, the synthesis of ultrathin fcc Au@Pt and Au@Pd rhombic nanoplates through the epitaxial growth of Pt and Pd on the hcp AuSSs, respectively, the first-time synthesis of 4H hexagonal phase Au nanoribbons (NRBs) and their phase transformation to fcc Au RNBs as well as the epitaxial growth of Ag, Pt and Pd on 4H Au NRBs to form the 4H/fcc Au@Ag, Au@Pt and Au@Pd core–shell NRBs, and the epitaxial growth of metal and semiconductor nanostructures on solution-processable transition metal dichalcogenide (TMD) nanoshees at ambient conditions, single- or few-layer metal dichalcogenide nanosheets and hybrid nanomaterials, the large-amount, uniform, ultrathin metal sulfide and selenide nanocrystals, other 2D nanomaterials, nanodots prepared from 2D nanomaterials, and self-assembled 2D nanosheets and chiral nanofibers from ultrathin low-dimensional nanomaterials. Then I will demonstrate the applications of these novel nanomaterials in chemical and bio-sensors, solar cells, water splitting, hydrogen evolution reaction, electric devices, memory devices, conductive electrodes, other clean energy, etc.
(Invited) A Systematic Approach to Develop and Validate Models for the Design of Membrane Electrode Assemblies
Authors: Putz Andreas Michael Vincent , Secanell Marc 
Published: February 2020

The modeling and simulation landscape for fuel-cells has increased dramatically over last years. A number of commercial and OpenSource (e.g. OpenFCST, FAST-FC, DuMux) software packages are available to the aspiring researcher or engineer in academia and industry.
The complexity ranges from purely analytic models with O(1) number of parameters to fully numerically models with O(100) input parameters. However, despite the apparent abundance on model and simulation tools, their practical use for the design of next generation MEA components like the catalyst layers or porous transport layers has been very limited and progress has been mainly driven by large, slow and expensive experimental studies. This stands in stark contrast to combustion engine design where virtual prototypes are built, tested and optimized through numerical simulations before a physical prototype is built. In the fuel-cell community this lack of application tends to be explained by the large number of equations and the corresponding computational resources needed to tackle the problem. The fact that combustion engineering does not suffer this problem, despite an equally high level of complexity, seems to indicate that numerical complexity is not the root cause.
Browsing the numerical codes and the modeling literature shows little consensus about the correct description of the individual physical effects. A few of the topics of disagreement are:

Gas transport: Fickian diffusion, Maxwelll-Stefan diffusion, Dusty Gas models, ...

Membrane water transport: concentration driven, liquid pressure driven, ...

Reaction at the catalyst surface: macro-homogeneous models, ionomer filled agglomerate models, water filled agglomerate models,thin film models, ...

Electrochemical reaction mechanisms: Tafel, Butler-Volmer, Double-Trap, Dual-Path, ...

...

In this tutorial, a consistent validation strategy with a focus on gas mass transport is outlined and demonstrated. We will take AFCCs baseline MEA model platform OpenFCST through a

validation with ex-situ experiments: Permeability and Diffusivity

validation through in-situ experiments:

Limiting current methods

Polarization curves under different operating conditions

Thickness variations

validation through imaging techniques:

Diffusion simulations on reconstructed catalyst layers

The impact of different model configurations will be studied and we will investigate if a validation strategy like this can pinpoint the weaknesses or strengths of the model configuration chosen.
References

OpenFCST (www.openfcst.org)

M. Bhaiya, A. Putz and M. Secanell, "Analysis of non-isothermal effects on polymer electrolyte fuel cell electrode assemblies", Electrochimica Acta, 147C:294-309, 2014. DOI: 10.1016/j.electacta.2014.09.051

Figure 1
(Invited) Coupling of Mechanical and Transport Phenomena in Ionomers
Authors: Goyal Priyamvada , Monroe Charles W 
Published: February 2020

In a polymer-electrolyte membrane (PEM) within a fuel cell, water transport can be driven by diffusive, electro-osmotic, and permeative mechanisms. The equilibrium thickness of a PEM is also known to change substantially with respect to both water content and applied pressure. Most physical models treat hydraulic permeation or diffusion/osmosis in isolation; those that account for both phenomena in parallel do not always incorporate the pressure in a way that permits the analysis of all possible boundary conditions. Kusoglu and Weber have recently highlighted the need for models that handle situations involving simultaneous gradients of both pressure and water activity across constrained, swelling membranes [1].
This talk will focus on our recent efforts to reconcile all the transport modes within a rigorous multicomponent transport formalism that incorporates standard diffusive properties such as ionic conductivity, water activity coefficient, water diffusivity, and electro-osmotic drag coefficient alongside elastic properties such as the bulk modulus and Poisson ratio. The key ideas are that a volume-explicit equation of state needs to be incorporated along with the typical governing equations that describe the membrane bulk, and that a momentum balance needs to be included to determine how stress is distributed within the membrane. Information embodied in the stress tensor is, in some sense, independent of the information in the diffusion driving force that accounts for molecular and pressure diffusion. Thus hydraulic and diffusive modes can be handled in parallel without any additional simplifications.
We will present a macroscopic model that describes the volume change of or water redistribution within vapor-equilibrated ionomers in freely swelling or constrained geometries. The model will be used to underpin simulations that show how strain arises (and is distributed) during typical water-flux measurements across vapor-equilibrated membranes [2]. Values of the key parameters will be discussed in light of literature data as well. An experimental program will be suggested through which the most important properties can be probed.

References

[1] A. Kusoglu and A.Z. Weber, “Electrochemical/Mechanical Coupling in Ion-Conducting Soft Matter,” The Journal of Physical Chemistry Letters
6(2015) 4547-4552.
[2] C.W. Monroe, T. Romero, W. Mérida, and M. Eikerling, “A vaporization-exchange model for water sorption and flux in Nafion,” Journal of Membrane Science
324 (2008) 1-6.
(Science for Solving Society’s Problems Challenge Grant Winner) Sustainable Water Treatment Using an SOFC-Based Combined Heat and Power System
Authors: Hays Thomas H , Wachsman Eric D 
Published: February 2020

Without adequate sanitation and a reliable supply of potable water, it can be very difficult for individuals in developing nations to pursue education or other activities that would improve themselves or their communities. Addressing this problem at the local level with a strategy of distributed water purification powered by local fuel resources will be very effective. Using methane derived from agricultural waste, durable small scale SOFC units can generate significant amounts of electricity and heat. By leveraging both electrical and thermal energy, very high system efficiency is possible. The fuel flexibility, modularity, and the all solid state nature of SOFCs make them ideal for operation in remote areas.
Electrical and thermal outputs from a biogas fueled SOFC are measured and total cell efficiency is calculated to inform design criteria for the proposed power units. Stability to sulfur contamination is determined by measuring voltage drop during operation at the current density corresponding to maximum power. Using the information gathered from these tests, a basic analysis of the system size and fuel requirements necessary for community level use is presented.
A Coupled Experimental/Numerical Approach for Tuning High-Performing SOFC-Cathode
Authors: Celikbilek Ozden , Jauffres David , Dessemond Laurent , Burriel Mónica , Martin Christophe L , Djurado Elisabeth 
Published: February 2020

The present study concerns the influence of the micro/nano-structural properties of LSCF (La0.6Sr0.4Co0.2Fe0.8O3−δ) and 60:40 vol.% LSCF/CGO (Ce0.9Gd0.1O2-δ) composite cathode films on their electrochemical behavior. Electrostatic spray deposition technique is used to deposit 10 μm-thick functional films (Fig. 1). Contrary to expectations, pure LSCF showed a better response compared to the composite material. It exhibits Area Specific Resistance (ASR) values as low as 0.021 and 0.068 Ω.cm2 at 650 ˚C and 600 ˚C respectively. These values are, to the best of our knowledge, one of the lowest reported to date for LSCF-6428 composition in open circuit voltage (OCV) condition.1 To better comprehend the complex relationships between material properties, processing, micro/nano structure and electrode performance, a simplified geometry representing the typical 10x10x10 μm3 porous columns of the electrodes is modelled by 3D finite element (FEM).2 ASR is computed with real microstructural parameters obtained from 3D FIB/SEM technique. On the other hand, it is also calculated by a simple volume-averaged analytical model (1D-ALS model)3 within an assumed macrohomogeneous geometry. The computed ASRs with these two relatively simple models are compared to experimental results and the relevance of such models for inhomogeneous microstructures like ‘columnar’ is discussed.
Figure 1: Microstructural characterization of the films a-c) LSCF, e-g) 60/40 vol.% LSCF/CGO composite films observed by SEM. 3D reconstructed images by FIB/SEM technique of (d) LSCF and (h) 60:40 LSCF/CGO composite.

Celikbilek, O., Jauffres, D., Dessemond, L., Burriel, M., Martin, C.L., Djurado, E.,(2015), to be submitted to J. Mat. Chem. A

Haffelin, A., Joos, J., Ender, M., Weber, A., Ivers-Tiffee, E. (2013). J. Electrochem. Soc. 160, F867–F876

Adler, S. B., Lane, J. A. & Steele, B. C. H. (1996). J. Electrochem. Soc. 143, 3554–3564

Figure 1
Thermodynamically and Electrochemically Activated Oxygen Surface Exchange Process in Lscf As Solid Oxide Fuel Cathode
Authors: Zhang Xinxin , Liu Xingbo 
Published: February 2020

In this paper, the thermodynamically (oxygen partial pressure) and electrochemically (overpotential) activated oxygen surface exchange process for LSCF were investigated. The oxygen surface (La0.6Sr0.4)0.995Co0.2Fe0.8O3-δ(LSCF) dense layer was successfully coated on Gd-doped CeO2(GDC) electrolyte by air brush spraying and pressing method with thickness 5-20µm. The electrochemical properties of the three electrode cells (LSCF/GDC/Pt) were characterized by electrochemical impedance spectrum under difference oxygen partial pressure and bias voltage conditions. One main arc under lower frequency was shown in the EIS pattern, which indicates that the rate limiting step focus on the surface oxygen reduction reaction. The surface oxygen exchange coefficients calculated based on the cathode polarization resistance is 0.25-3.5×10-7 cm/s for LSCF at 700oC in the range of 0.0002-0.2 atm, and decrease with increasing the oxygen partial pressure. Similar tendency was observed in the variation of the bias voltage from -0.1-0.1 V, corresponding withk values 0.75-1.8×10-7 cm/s. However,the uncoordinated relationshipon k values was obtained between oxygen partial pressure and bias voltage based on the Nernst equation, where the slope for the variation of bias voltage is lower than that for the variation of oxygen partial pressure. The theoretical defect concentration and electrostatic potential in the cathode were analyzed under different oxygen partial pressure and bias voltages. It indicates thatboth surface oxygen vacancy concentration influenced by thegradient of the oxygen vacancy in bulk electrode under bias voltage and the surface over-potential relating with the charged oxygen species coverage work on this deviation.
Effect of Thermal Treatment on Structural/Electrical Properties of Protective Oxides for SOFC Metallic Interconnects
Authors: Tsai Shu-Yi , Fung Kuan-Zong , Ni Chung-Ta 
Published: February 2020

For intermediate temperature SOFC applications, metallic interconnects, such as Crofer 22H, have been used to replace ceramic interconnects in SOFC stacks because they are less expensive, more conductive and able to form complex shapes. Most metallic interconnects use chromium-containing alloy that form chromia scales at high temperatures. Since chromia may react with cathode and cause degradation, a protective oxide may be used to suppress the growth of chromia. Several techniques have been adopted to deposit oxides on metallic interconnects, thermal spray is found to be an appropriate technique. Thermal spray coating process has been used to produce a high quality coating by a combination of high temperature, high energy heat source, a relatively inert spraying medium, usually argon, and high particle velocities. This process allows the spraying of various types of metallic or ceramic coatings on to a wide range of substrate materials. As a result, uniform coating layer with excellent bond strength to substrate is obtained without noticeable distortion.

However, the temperature during thermal spraying may be high enough to change the crystal structure and conductivity of protective oxides. The heat treatment is believed to be an appropriate method to obtain adequate properties for protective oxide.
In this study, conducting oxides were deposited on metallic interconnect using plasma spray technique. However, the deposition temperature for thermal spray coating may be high enough to change the crystal structure and conductivity of protective oxide. The post annealing at elevated temperature is found to be an appropriate method to obtain adequate properties for protective oxide. Thus, the objective of this work is to investigate the effect of annealing on the crystal structure and conductivity of the sprayed oxide. The crystal structure, morphology and electrical conduction of interconnect with sprayed oxide films will be examined by using XRD, FESEM and resistance measurement.
Internal Partial Pressure and Durability of Bcy Based Protonic Ceramic Fuel Cells As a Function of Electrolyte Thickness
Authors: Lim Hyung-Tae 
Published: February 2020

Internal partial pressure in BCY based solid oxide fuel cells were measured as a function of electrolyte thickness. The measurements of internal ΔΦ were conducted on the thin (~ 10 µm) and thick (~ 50 µm) BCY electrolyte using an embedded Pt probe, and it was observed that ΔΦ depends on the electrolyte thickness. Using the values of internal ΔΦ, internal hydrogen and oxygen partial pressure were calculated, and it was found that the internal partial pressure changes with electrolyte thickness. Thin BCY cells are dominated by the near-cathode gases rather than the near-anode gases, indicating it is more vulnerable to water vapor produced at the cathode during fuel-cell operation. The correlation between internal partial pressure profile and performance durability were also investigated. CC tests were conducted on a thin (~ 10 µm) BCY-electrolyte cell with BCY + LSCF cathode, and on a thick (~ 35 µm) BCY electrolyte cell with BZY + LSCF cathode, at positive and negative cell voltage. The former showed a rapid rate of voltage drop under all operating conditions, while the latter showed much more stable performance, even when operating at a negative voltage. No changes in microstructure and composition were detected in the thick BCY electrolyte or the BZY + LSCF cathode. Thus, the present work shows the effect of the electrolyte thickness and cathode-material selection on the durability of BCY based cells, in terms of internal partial pressure.
Conductivity of La0.9M0.1NbO4(M=Sm, Gd, Yb) As High Temperature Proton Conductors
Authors: Cao Yong , Duan Nan-Qi , Xiong Chuanyan 
Published: February 2020

La0.9M0.1NbO4-
d (M=Sm, Gd, Yb) were prepared via a solid reaction route and single phase was attained by calcining constituent oxides at 1200 ˚C for 5 h. Their phase crystal structure, microstructure and conductivity were investigated. The total conductivity of LaNbO4 was improved by Sm, Gd, Yb doping, which was mainly attributed to the introduction of oxygen vacancy, and followed the order as La0.9Sm0.1NbO4-
d > La0.9Gd0.1NbO4-
d >La0.9Yb0.1NbO4-
d, as shown in the figure acttached. The highest conductivity (1.76×10-4 S cm-1) was achieved for La0.9Sm0.1NbO4-
d at 800 ˚C in wet air, more one order higher than that of LaNbO4.

Figure 1
Development of the Oxide Ion Conductor Na0.5Bi0.5TiO3 (NBT) for Solid Oxide Cells
Authors: Tumilson Christopher , Hardacre Chris , Jacquemin Johan , Elder Rachael H , Sinclair Derek C 
Published: February 2020

Na0.5Bi0.5TiO3 (NBT) is a well-known lead-free piezoelectric material with potential to replace lead zirconate titanate (PZT),1 however high leakage conductivity for the material has been widely reported.2 Through a combination of Impedance Spectroscopy (IS), O2- ion transference (EMF) number experiments and O18 tracer diffusion measurements, combined with Time-of-flight Secondary Ion Mass Spectrometry (TOFSIMS), it was identified that this leakage conductivity was due to oxygen ion conductivity. The volatilization of bismuth during synthesis, causing oxygen vacancies, is believed to be responsible for the leakage conductivity.3 The oxide-ion conductivity, when doped with magnesium, exceeds that of yttria-stabilized zirconia (YSZ) at ~500 °C,3 making it a potential electrolyte material for Intermediate Temperature Solid Oxide Cells (ITSOCs). Figure 1 shows the comparison of bulk oxide ion conductivity between 2 at.% Mg-doped NBT and other known oxide ion conductors.
As part of the UK wide £5.7m 4CU project, research has concentrated on trying to develop NBT for use in Intermediate Temperature Solid Oxide Cells (ITSOCS). With the aim of achieving mixed ionic and electronic conduction, transition metals were chemically doped on to the Ti-site. A range of experimental techniques was used to characterize the materials aimed at investigating both conductivity and material structure (Scanning Electron Microscopy (SEM), IS, X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS)). The potential for NBT as an ITSOC material, as well as the challenges of developing the material, will be discussed.
(1) Takenaka T. et al. Jpn. J. Appl. Phys
1999, 30, 2236.
(2) Hiruma Y. et al. J. Appl. Phys
2009, 105, 084112.
(3) Li. M. et al. Nature Materials
2013, 13, 31.

Figure 1