bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ordered Three Dimensional Electrodes for Enhanced Mass Transfer
Authors: Hereijgers Jonas , Lölsberg Jonas , Wessling Matthias , Breugelmans Tom 
Published: February 2020

Over the last decade, the use of nanotechnology in electrochemical catalysis has become extreme popular [1]. Sole electrocatalytic nanoparticles, however, do not yet constitute an electrode. Hence, deposition on a conducting support structure is indispensable. While the electrocatalytic activity is in general well understood using typical electrochemical techniques such as cyclic and linear voltammetry whether or not coupled with controlled mass transfer conditions like rotating disk electrodes, the impact of concentration polarization is often neglected. Operating under current limiting regime, mass transfer enhancement in electrochemical reactors is a key factor not only for current density but also for the selectivity and stability [2]. Inducing convective transport, however, is limited to the incorporation of turbulence promoters. Either stating an increase in inter-electrode distance or a large power dissipation to pump the feed.
Looking at electrochemical reactors (e.g. fuel cell, chloor-alkali process, water electrolyzer) the conductive support typically consist of a flat substrate with the electrolyte flowing sideways along the electrode [3]. Inevitably a stagnant boundary layer arises which reacting species have to surpass to reach the electrocatalytic surface, even when using turbulence promotors. As transport across this stagnant layer is solely due to diffusion it has a major impact on the mass transfer resistance and concomitantly on the position of the limiting current plateau. However, when the electrode is no longer considered as a flat substrate a plethora of options arise, where not only the surface area can be increased, but also where the electrode itself can provoke mixing effects, reducing this boundary layer.
In the present work such integrated mixer and electrode configurations have been constructed and evaluated using additive manufacturing technology. Doing so these electrode mixers shift the limiting current plateau with over 70%. At the one hand this is attributed due to shear forces reducing the stagnant boundary layer, at the other hand as no longer a turbulence promotor or even a spacer is required the inter-electrode distance can be reduced to sub-millimeter range, having a beneficial impact on the ohmic resistance.

References:

A. Kloke, F. Von Stetten, R. Zengerle, S. Kerzenmacher, Strategies for the fabrication of porous platinum electrodes. Adv. Mater.
23, 4976–5008 (2011).

C. J. Brown, F. C. Walsh, J. K. Hammond, D. Robinson, Local mass transport effects in the FMO1 laboratory electrolyser. J. Appl. Electrochem.
22, 613–619 (1992).

D. Pauwels et al., The application of an electrochemical microflow reactor for the electrosynthetic aldol reaction of acetone to diacetone alcohol. Chem. Eng. Res. Des.
128, 205–213 (2017).
Electrochemical Behaviour of Iron in Molten Oxides
Authors: Judge William David , Azimi Gisele 
Published: February 2020

Owing to their versatility, iron and steel are among the most widely used engineering materials with about 1.6 billion tonnes produced in 2016. The conventional extraction process based on blast furnaces relies heavily on carbon, thus the production of iron and steel accounts for 4-7% of all anthropogenic CO2 emissions [1]. Due to recent environmental regulations and global action to mitigate climate change, attention has begun to target the environmental aspects of the steelmaking technology, and to this end research activities have begun around the world to develop breakthrough environmentally sound low carbon alternative processes. Among proposed processes, the most promising is based on molten electrolysis, because electricity has the potential to be carbon-free when produced from renewable resources.
Within the electrochemical regime, molten oxides are an attractive medium for extraction of iron for a number of reasons [2]. Their high solubilizing power allows iron ore to be directly fed to the electrolytic cells, while their low vapor pressure allows electrolysis to be conducted above the melting point of iron, which greatly improves throughput, and most importantly, oxide ions in the melt can be discharged as environmentally benign oxygen gas if anode materials are inert. Consequently, there has been considerable effort to develop a molten oxide electrolysis process for iron [3]. However, there remain fundamental uncertainties regarding the electrochemistry of iron in molten oxides [4], thus the process has not yet been commercialized.
In this work, we present recent fundamental and experimental investigations into the electrochemical behaviour of iron in molten oxides, with the aim of understanding mechanisms that govern electrolysis. Attention is given to the design and testing of supporting electrolytes to minimize electronic conduction in the melt and improve the current efficiency of the process. At the same time, the performance of supporting electrolytes with respect to viscosity, surface tension, diffusivity, ionic conductivity, and liquidus temperature are considered. The results of fundamental investigations were used to strategically direct experimental investigations.
[1] Energy Technology Perspectives 2017. International Energy Agency: Paris (2017): 76-79.
[2] D.R. Sadoway. "New Opportunities for Metal Extraction and Waste Treatment by Electrochemical Processing in Molten Salts." J. Mater. Res. 10 (1995): 487-492.
[3] A. Allanore. "Features and Challenges of Molten Oxide Electrolytes for Metal Extraction." J. Electrochem. Soc. 162 (2015): E13-E22.
[4] W.D. Judge, A. Allanore, D.R. Sadoway, and G. Azimi. "E-logp
O2 diagrams for ironmaking by molten oxide electrolysis." Electrochim. Acta 247 (2017): 1088-1094.
Thermodynamic and Kinetic Database for Hydration, Protonic Diffusion and Stability in Doped-BaHfO3 As High-Temperature Proton Conducting Electrolyte
Authors: Zhang Lei , Liu Meilin 
Published: February 2020

Perovskite-type proton conducting materials is widely used as solid state electrolyte in Solid Oxide Fuel Cells (SOFCs), due to its excellent mechanical and thermodynamic stability and considerable proton conductivity. Developing novel materials via atomistic level simulation techniques is cost-effective and highly-efficient. In this abstract, we demonstrated the thermodynamic and kinetic database constructed for A and B-site doped BaHfO3, i.e. a novel proton-conducting perovskite system. We took advantage of ab-initio density functional theory calculations, transition state and diffusion theory, along with statistical thermodynamics. We successfully computed the key physical quantities relevant in hydration, proton conduction, and degradation process. The data obtained was analyzed through a data-science approach, by correlating computed quantities with intrinsic dopant properties, e.g. ionic radius, electro-negativity, etc. In the end, quantitative descriptors within fitting equations can be established for predicting unexplored dopants.
This set of methods, including data-analytics, can be viewed as a standard way in constructing thermodynamic and kinetic database for other solid state ionic materials.

Figure 1
Nanoconfinement for Multi-Step Reaction Cascade System
Authors: Chavan Kanchan Suklal , Calabrese Barton Scott 
Published: February 2020

Multi-step reaction can be carried out efficiently using integrated catalytic system for the manufacture of advanced materials, energy conversion and harvesting, and human-machine interfaces. Nature has shown effective way to carry out multi-step reaction through substrate channeling.1 Molecular tunneling2 and electrostatic guidance3 mechanisms of substrate channeling has been studied extensively in literature and has proven their potential for efficient substrate channeling with minimum intermediate diffusional loss.
Molecular tunneling restricts intermediate diffusion through tunnel wall between active sites, whereas, electrostatic guidance restricts intermediate through surface interaction. Incorporating these two mechanisms into multi-step reaction system can lead to innovative integrated catalytic system.
In this work, continuum modeling has been performed on geometry consist of tunnel and two active sites confined within. Tunnel surface is oppositely charged as of intermediate to introduce electrostatic interaction. System is governed by diffusion and migration as well as reaction kinetics. Effect of reaction kinetics and transport has been studied and defined as Damköhler number. Channeling efficiency is defined by product yield at second active site relative to intermediate production at first active site. Effect of geometrical parameter such as distance between active site (d), distance between active site and bulk (le
), tunnel diameter(h) as well as ionic strength (I) of the system has been studied. Minimizing intermediate access to the bulk and increasing driving force for the intermediate to transport to active site is required for efficient channeling.
References:

I. Wheeldon, S. D. Minteer, S. Banta, S. C. Barton, P. Atanassov and M. Sigman, "Substrate channelling as an approach to cascade reactions", Nat. Chem., 8, 299–309 (2016). doi:10.1038/nchem.2459.

E. W. Miles, S. Rhee and D. R. Davies, "The molecular basis of substrate channeling", J. Biol. Chem., 274, 12193–12196 (1999). doi:10.1074/jbc.274.18.12193.

A. H. Elcock, G. A. Huber and J. Andrew McCammon, "Electrostatic channeling of substrates between enzyme active sites: Comparison of simulation and experiment", Biochemistry, 36, 16049–16058 (1997). doi:10.1021/bi971709u.
Review of Capacity Fade Models for Lithium-Ion Batteries - Numerical Implications of SEI Layer Growth
Authors: Fan Mengdi , Lee Seong Beom , Pathak Manan , Qi Yanbo , Chen Jerry , Subramanian Venkat R. 
Published: February 2020

Lithium-ion battery applications, such as EVs and PHEVs, require long battery life. However, capacity fade always occurs due to unwanted side reactions including electrolyte oxidation at the positive electrode, lithium deposition at the negative electrode, electrolyte decomposition processes, and formation of the Solid-Electrolyte Interphase (SEI) layer1. To model the capacity fade, different models have been proposed in the literature2-4.
In this presentation, we model the capacity fade by assuming the SEI layer formation to be the dominant mechanism. We address how to efficiently simulate SEI layer growth and modify the simulation approach for the solid phase equations if needed. Even within SEI layer models, several different expressions have been used in many papers5-8. In most cases, the solid particles are assumed to be spherical, and the intercalation process is modeled using Fick’s law of diffusion in the radial direction. For solving the solid-phase diffusion in the radial-dimension, many efficient methods to reformulate and simulate have been proposed in the past9-12.
The SEI forming side reaction with the Single Particle Model (SPM) is first studied. The partial differential equation of the SPM is discretized using the finite difference method in radial direction and solved in time using the numerical method of lines approach. An assumption of a parabolic profile in the radial direction is another efficient approximation9-12. After this, we combine the SEI layer model with the pseudo two-dimensional model to predict the performance of the battery.

Acknowledgements

The authors thank the Department of Energy (DOE) for providing partial financial support for this work, through the Advanced Research Projects Agency (ARPA-E) award number DE-AR0000275.

References

P. Arora, R. E. White, M. Doyle, J. Electrochem. Soc., 145, 3647-3667 (1998).

J. Park, J. H. Seo, G. Plett, W. Lu, A. M. Sastry, Electrochem. Solid-State Lett., 14, A14 (2011).

Y. Dai, L. Cai, R. E. White, J. Electrochem. Soc., 160, A182 (2013).

X. Lin, J. Park, L. Liu, Y. Lee, A. M. Sastry, J. Electrochem. Soc., 160 (10) A1701-A1710 (2013).

M. Safari, M. Morcrette, A. Teyssot, and C. Delacourt, J. Electrochem. Soc., 156(3), A145-A153 (2009).

P. Ramadass, B. S. Haran, P. M. Gomadam, R. H. White, and B. N. Popov, J. Electrochem. Soc., 151, A196 (2004).

M. B. Pinson, M. Z. Bazant, J. Electrochem. Soc., 160 (2) A243-A250 (2013).

H. Ekström, G. Lindbergh, J. Electrochem. Soc., 162 (6) A1003-A1007 (2015).

C. Y. Wang, W. B. Gu, and B. Y. Liaw, J. Electrochem. Soc., 145, 3407 (1998).

W. B. Gu, C. Y. Wang, and B. Y. Liaw, J. Electrochem. Soc., 145, 3418 (1998).

P. W. C. Northrop, V. Ramadesigan, S. De and V. R. Subramanian, J. Electrochem. Soc., 158 (12) A1461-A1477 (2011).

V. Boovaragavan, V. Ramadesigan, and V. R. Subramanian, J. Electrochem. Soc.,
157 (7) A854-A860 (2010).
Physical-Statistical Modeling and Analyses of Catalyst Degradation in PEM Fuel Cells
Authors: Baroody Heather Ann , Stolar Drew , Eikerling Michael Hermann 
Published: February 2020

Platinum durability in the catalyst layers of polymer electrolyte fuel cells is a major challenge that delays the full commercialization of fuel cell vehicles. This work presents a physical-statistical model of platinum degradation. The modeling framework of the Pt degradation model encompasses the main processes at the particle level, namely catalyst dissolution, redeposition, coagulation, and detachment, and it accounts for the effluence of Pt ions into the polymer electrolyte membrane. Data sets analyzed with the model encompass
information on changes in electrochemically active surface area, particle radius distribution, Pt mass distribution, and thickness of the catalyst layer. A systematic algorithm is developed to process experimental inputs and generate output information on kinetic rate parameters. The model-based data treatment proceeds in two stages: (i) statistical exploration of the complete parameter space using Monte Carlo techniques and (ii) an optimization routine to deconvolute contributions to degradation by different mechanisms and
determination of the pertinent set of parameters. Model outcomes contribute to fuel cell performance and lifetime evaluation, development of strategies for degradation mitigation, and calibration of efforts in design and fabrication of catalyst materials and catalyst layers.
Nonlinear Impedance Spectra Analysis of CO Poisoning on PEM Fuel Cell Performance
Authors: Pachimatla Rajesh , Srinivasan Ramanathan 
Published: February 2020

In polymer electrolyte membrane (PEM) fuel cells, hydrogen is the preferred fuel with air or oxygen as oxidant. However, many a time, the presence of carbon monoxide (CO), even at low ppm levels, inhibits the hydrogen oxidation reaction [1, 2]. In this work, we describe nonlinear impedance spectra analysis (NLEIS) of CO poisoning in PEM fuel cells. In NLEIS method, large amplitude perturbations are employed and the resulting signal have significant higher harmonic components, which, if acquired, can provide additional information about the system under investigation. Here we illustrate a NLEIS methodology in which governing equations were solved without linearization, using numerical method. The response signal was subjected to fast Fourier transform (FFT) to extract magnitude and phase at fundamental and higher harmonics. In this study, linear adsorption model, in which a CO molecule occupies one adsorption site was employed to generate NLEIS data [3]. Figure 1 shows the concentration effect on NLEIS results, simulated under galvanostatic mode employing large (Iac = 200 mA) amplitude perturbation at Idc =200 mA.cm-2
. The results show that the CO poisoning effects are more easily distinguishable at higher harmonics, when compared to the response at fundamental frequency.

Key words: Nonlinear EIS, PEM fuel cell, CO poisoning, linear adsorption model

References:

[1]. L. Carrette, K.A. Friedrich and U. Stimming, Fuel Cells
1, 5 (2001)
[2]. J. Zhang, H. Wang, D. P. Wilkinson, D. Song, J. Shen and Z. S. Liu, J. Power Sources ,147, 58 (2005)
[3]. T. E. Springer, T. Rockward, T. A. Zawodzinski and S. Gottesfeld, J. Electrochem. Soc.

148, A11 (2001)

Figure 1
(Invited) Homoepitaxial GaN Growth on Free-Standing Substrates
Authors: Hite Jennifer K , Anderson Travis J , Mastro Michael A , Luna Lunet E , Gallagher James C , Eddy Charles R. 
Published: February 2020

The availability of high quality, free-standing GaN substrates opens windows for new device applications in III-nitrides, especially in vertical structures. With the introduction of these native substrates, the properties of nitrides are no longer dominated by defects introduced by heteroepitaxial growth. However, additional materials challenges are coming to the forefront that need to be understood and surmounted in order to allow homoepitaxial devices to achieve their full potential.
In order to enable device-quality epitaxial layers, a deeper understanding of substrate preparation and the effects of the substrate and growth initiation on the characteristics of the epitaxial layers is required for metal organic chemical vapor deposition (MOCVD) growth of homoepitaxial films. We investigate these effects on epi morphology, uniformity, and impurity incorporation at the interface and in the films. Although the initial substrate factors influencing the epi can be subtle, they can have far reaching impact on device performance. By studying these effects using wafers from several different vendors, with substrates from both hydride vapor phase epitaxy (HVPE) and ammonothermal techniques, an understanding of the requirements for device quality MOCVD homoepitaxy can be determined.
Interface State Density of Atomic Layer Deposited Al2O3 on Beta-Ga2O3
Authors: Su Chen Yi , Hoshii Takuya , Muneta Iriya , Wakabayashi Hitoshi , Tsutsui Kazuo , Iwai Hiroshi , Kakushima Kuniyuki 
Published: February 2020

Abstract

In this study, an atomic layer deposited (ALD) Al2O3 with a thickness of 40 nm was used as a dielectric layer for gallium oxide (Ga2O3) metal-oxide-semiconductor (MOS) capacitors. Interface state (D
it) of 1.6×1012 cm-2/eV was extracted at 0.7 eV from conduction band (E
C).

Introduction

β-Ga2O3 is a promising candidate for power device applications due to its wide bandgap of 4.7–4.9 eV with a breakdown electric field 8 MV/cm, which is about three times larger than those of SiC and GaN power device materials. Along with the reports on high voltage Schottky diodes, MOS transistors have now been reported. In this research, ALD-Al2O3 with a thickness of 40 nm has been used as a gate dielectric and its interface properties are investigated.

Experiment

A 40-nm-thick-Al2O3 gate dielectric film was deposited by ALD on the surface of a Ga2O3 substrate with n-type epitaxial layer. The doping density (N
d) of the epitaxial layer was 2.3×1016 cm-3. The samples were transferred to a sputter chamber and 50-nm-thick W film followed by 50-nm-thick TiN was deposited by RF magnetron sputtering as a gate electrode. The capacitor was patterned by reactive ion etching (RIE) to form gate electrodes. Finally, a 10-nm-thick Ti followed by a 50-nm-thick TiN was deposited on the backside of the substrate as an Ohmic contact. Figure 1 shows the schematic illustration of the fabricated MOS capacitor.

Results

Capacitance-voltage (C-V) curves measured from 1 kHz to 100 kHz are shows in fig.2. The equivalent oxide thickness (EOT) of the dielectric layer was 18.3 nm. The D
it of the capacitor was evaluated by conductance method. Figure 3 shows the extracted D
it distribution in the bandgap of Ga2O3, where a 1.6×1012 cm-2/eV was obtained at 0.7 eV from E
C.

Conclusion

Interface property of Al2O3/β-Ga2O3 was evaluated by conductance method. A 1.6×1012 cm-2/eV was obtained at 0.7 eV from E
C.

References

[1] M. Higashiwaki et al., Appl. Phys. Lett, 103, 123511 (2013)
[2] K. Zeng, Y. Jia, and U. Singisetti, IEEE Electron Device Lett. 37, 906 (2016)

Figure 1
Multiplexed CVD Biomarker Detection in Human Serum Using Aptamer Immobilized High Electron Mobility Transistor
Authors: Tai Tse-Yu , Sinha Anirban , Lee Gwo-Bin , Wang Yu-Lin 
Published: February 2020

Cardiovascular diseases (CVDs) are the major causes of death in the world today. Identifying and managing CVD risk is of primary importance in efficient patient care. Proper risk assessment strategies can provide information to healthy as well as high risk individuals on how to better manage their health. This can greatly reduce the mortality rate of cardiovascular disease. Using protein based cardiac biomarkers for risk assessment can improve early diagnosis and aid in prognosis of CVDs. Semiconductor based electronic sensors are very attractive for rapid and sensitive protein detection. Highly Electron Mobility Transistor (HEMT) based sensors have been used in a variety of applications such as ion, gas and biomolecule sensing and possess desirable features such as high sensitivity and resistance to harsh chemical environment. In this research, A unique sensing methodology using AlGaN/GaN HEMT has been developed to directly detect target protein in high salt concentration environment. The target protein was captured on the surface of the gate electrode, which is separated from the transistor channel by a small gap, and functionalized with target specific aptamer. By forming an electrical double layer (EDL) structure, the solution capacitance modulates the FET drain current. In this way, highly sensitive determination of cardiac biomarkers in high ionic strength media such as 1X PBS and human serum can be realized.
HEMT is fabricated using 4 mask processes: mesa isolation and defining active device area, ohmic contact deposition and annealing, metal interconnect deposition and device passivation. For electrical measurement, a pulsed gate electrode voltage is supplied to the gate electrode which creates a solution capacitance in the gap between the gate electrode and transistor dielectric. This solution capacitance modulates the potential drop across the transistor dielectric and hence the drain current. The solution capacitance changes when the device is functionalized with the target specific aptamer and when the target protein binds to the receptor. The aptamer based AlGaN/GaN HEMT biosensor can detect target proteins with high sensitivity, selectivity and a wide dynamic range of detection in 1X PBS (with 4% BSA) and clinical human serum samples.
Copper Oxide-Based Photocathodes and Electrocatalysts for the (Photo)Electrochemical Reduction of Protons and Carbon Dioxide
Authors: Mayer Matthew T. , Schreier Marcel , Luo Jingshan , Graetzel Michael 
Published: February 2020

The use of renewable electricity to drive chemical reactions is an approach to storing the energy from intermittent sources (solar, wind) in the form of chemical bonds. Combining photoabsorber and electrocatalytic components into integrated devices, we developed copper oxide-based photocathodes for proton reduction to hydrogen (1,2), as well as carbon dioxide reduction to carbon monoxide (3), in demonstrations of efficient solar-to-fuels conversion.
Recently, oxide-derived copper emerged as an intriguing electrocatalyst for the conversion of carbon dioxide into hydrocarbon products. In an effort to modify the product selectivity of copper oxide nanowire arrays, we used atomic layer deposition to apply conformal layers of tin oxide to the electrode surface. This copper-tin-oxide hybrid exhibited nearly unity selectivity for carbon monoxide as CO2 reduction product, deviating significantly from the behavior expected for copper or tin alone, neither of which typically produce CO at high selectivity. This result suggests sub-monolayer composition modification of electrode surfaces can be a powerful strategy for tuning electrocatalyst selectivity.

J. Luo, L. Steier, M.-K. Son, M. Schreier, M. T. Mayer and M. Grätzel, Nano Letters, 2016, 16, 1848–1857.

P. Dias, M. Schreier, S. D. Tilley, J. Luo, J. Azevedo, L. Andrade, D. Bi, A. Hagfeldt, A. Mendes, M. Grätzel and M. T. Mayer, Adv. Energy Mater., 2015, 5, 1501537.

M. Schreier, J. Luo, P. Gao, T. Moehl, M. T. Mayer and M. Grätzel, J. Am. Chem. Soc., 2016, 138, 1938–1946.

M. Schreier, F. Héroguel, L. Steier, S. Ahmad, J. S. Luterbacher, M. T. Mayer, J. Luo and M. Grätzel, Nature Energy, 2017, 2, 17087.