bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Short Current on the Open Circuit Voltage in a Solid Oxide Fuel Cell
Authors: Lee Choong-Gon , Koomson Samuel , Arthur Ebenzer
Published: February 2020

The solid oxide fuel cell (SOFC) is a promissing power source with its strong point of solid oxide electrolyte. It allows long time operation without electrolyte supplying. But the electroylte in the SOFC must be very thin to reduce the internal resistance. Thinner electrolyte provides better performance.

In my laboratory, a 100 cm2 class SOFC has been operated. It was supplyed from a SOFC maker in Korea. Since it has several tenth micrometer of electrolyte thickness, it showed voltage behavior of short current when the inert gas step addition (ISA) method [1] was employed. The ISA was firstly used to investigate the flow and partial pressure effect on the performance of molten carbonate fuel cell (MCFC). The method adds nitrogen gas to the anode flow, simultaneously it raises reactant gas flow until the added nitrogen arrives at the cell. Indeed, the nitrogen addition port places about 5 m ahead of the anode cell with 1/4 inch stainless tube, thus several seconds are required to reach to the cell. In the MCFC, there was no voltage change during the period of seveal seconds at open circuit state. Since there was no applied current, it has no doubt. But the SOFC showed clear voltage increase at the tiem period by the nitrogen addition although it was at open circuit state. It is clearly compared with that behavior of MCFC.

In this presentation, the difference will be investigated in terms of short current at the SOFC.

[1] C.-G. Lee, B.-S. Kang, H.-K. Seo, H.-C. Lim, J. Electroanal. Chem., 540, 169–188 (2003).
(Invited) A New Transmission X-Ray Microscope Beamline at the NSLS-II
Authors: Lee Wah-Keat , Ge Mingyuan , Xiao Xianghui , Coburn Scott , Nazaretski Evgeny , Xu Weihe , Xu Huijuan , Gofron Kazimierz , Yin Zhijian
Published: February 2020

The Transmission X-ray Microscope (TXM) has proven to be a very useful tool for energy storage systems research. It has been used to study, in 2D and 3D, the morphological and chemical state changes in energy storage systems with several tens of nanometer spatial resolution. Up until recently, however, the typical data acquisition time for a single energy 3D tomography data set is usually between 20-240 minutes at a synchrotron. In this talk, we present a new TXM instrument at the Full-field X-ray Imaging (FXI) beamline at the National Synchrotron Light Source II at Brookhaven National Laboratory. At FXI, a full 3D tomography data set can be collected in one minute. This capability opens up new modes of measurements which previously were time-prohibitive, such as 3D XANES or EXAFS, and the ability to measure a large number of samples for statistical significance. The technical details of the beamline and the instrument, as well as some early measurement examples will be discussed.
(Invited) Enhancing SOFC Anode Stability through Atomic Layer Deposition
Authors: McIntosh Steven , Gorte Raymond J , Vohs John M. , Curran Christopher
Published: February 2020

Ni-YSZ cermet anodes are highly optimized to achieve good mechanical strength and electrochemical performance. However, they still suffer from sensitivity to impurities like sulfur, poor redox stability, and a tendency to form carbon fibers if the H2O:C ratio is too low or there are higher hydrocarbons in the feed to the cell. In this project we utilize atomic layer deposition (ALD) to grow thin oxide films onto the anode surface to enhance both the thermal stability and coking tolerance of the Ni-YSZ cermet. We have developed an ALD system that enables controlled, sub-monolayer conformal coating of mixed metal oxide films. The growth process, coverage, composition and operational stability of these films is carefully analyzed utilizing a unique High-Sensitivity Low Energy Ion Scattering (HS-LEIS) instrument that provides the composition of the outermost atomic surface layer of the material. This ex-situ characterization is closely correlated to the electrochemical performance of the anodes.
(Invited) Ionic Conducting Ceramic Membranes – Potential Applications - Materials - Components – Transport in Asymmetric Structures
Authors: Meulenberg Wilhelm A. , Baumann Stefan , Schulze-Küppers Falk , Deibert Wendelin , Guillon Olivier
Published: February 2020

Ceramic mixed ionic-electronic conducting membranes can be used for the separation of single gases (e.g hydrogen or oxygen) from gas mixtures or in membrane reactors. Ceramic membrane reactors (CMR) offer an opportunity to combine separation processes directly with chemical reactions, leading to process intensification and, hence, benefits with regard to efficiency. This integral coupling of both processes, separation and reaction, generates synergies between them. Current research activities focus on membrane reactors due to their high intrinsic efficiency and great potential for the production of a large variety of commodity chemicals, energy carriers, and synthetic fuels. This includes the reduction of CO2 emissions and the utilisation/valorisation of CO2.

The development of ceramic membrane materials for such devices is focussed on performance and stability (chemical and thermal) in application relevant environment. The operating temperature is between 400-850°C. The presentation covers a series of potential stable materials for oxygen- and hydrogen ion conducting membranes and their characterisation and performance in application oriented conditions. To reach a high performance of the membrane systems thin film membranes, active surface layers and thermochemical and -mechanical stable supports with designed porosity are required.

The production and characterization of membrane structures is explained using the example of sequentially tape cast and laminated supported membranes. Furthermore, the ion and gas transport through such supported thin membranes is described and an example of transport modelling will be given. Finally, the construction of a Proof of Concept membrane reactor for oxygen separation in oxyfuel cement industry or the use in fossil fuelled power plants will be shown. The lecture concludes with an outlook on future development directions.
Electrochemical Characterization of Ion Exchange Composite Membrane with Various Ion Exchange Group Moieties
Authors: Son Tae Yang , Ko Tae Ho , Kim Ki Hyun , Nam Sang Yong
Published: February 2020

In this study, ion exchange membranes were prepared by sulfonating and aminating the same polymer with different equivalents respectively. Thereafter, the most suitable equivalent amount of the polymer was selected and used for the study. The selected polymer was impregnated into a support in a solution state to prepare a reinforced composite membrane having excellent mechanical strength. The ion exchange capacity tends to decrease with the use of a support. In order to compensate this, the particles are mixed with the polymer solution to maintain the existing performance.

FE-SEM was used to confirm particle dispersion in the membrane, and quantitative analysis was performed using FT-IR. In addition, thermal properties were analyzed using TGA and DSC, and electrochemical characteristics were analyzed through ionic conductivity / membrane resistance / I-V curves.
(Invited) Nano-Structured ORR Catalysts for PEM Fuel Cells
Authors: Lim JeongHoon , Cho EunAe
Published: February 2020

Polymer electrolyte membrane fuel cells (PEMFCs) are the most attractive power source for zero-emission vehicles owing to their environmental friendliness, high energy efficiency, and high power density. However, their high cost and low durability have prevented PEMFCs from being fully implemented and commercialized, mainly due to the use of platinum as a catalyst to overcome the sluggish kinetics of the oxygen reduction reaction (ORR) in the cathode. To reduce the use of Pt, extensive studies have been conducted and a large variety of ORR catalysts have been developed, such as Pt-M alloys as well as shape-controlled, dealloyed, and structurally ordered catalysts. Although those catalysts exhibited excellent intrinsic activity in aqueous environment, they have been hardly implemented in membrane-electrode assemblies (MEAs) for practical application.

In this talk, we report Pt-M intermetallic catalysts and M-doped PtNi octahedral nanoparticles on a carbon support (M-PtNi/C) that exhibit superior catalytic activity and stability in half-cell and MEA tests as an ORR catalyst for PEMFCs. To prevent agglomeration of Pt-M nanoparticles during heat treatment in which to transform the Pt-M alloy into Pt-M intermetallic structure, a facile synthetic process was conducted at low temperatures. Octahedral PtNi nanoparticles are known as one of the best ORR catalyst with its superior activity toward ORR. However, dissolution of Ni from the surface and collapse of the octahedral shape degrade the activity rapidly under the PEMFC operation conditions. To stabilize Ni and the octahedral shape, small amount of dopant was incorporated into the surface of octahedral PtNi. Electrochemical, chemical, and structural stability was thoroughly investigated through a harsh durability test. The effects of intermetallic structure and doping elements on the surface properties of Pt-based nanoparticles were examined by X-ray absorption fine structure (XAFS) analysis and density functional theory (DFT) calculation.
Embedded Reference Electrode in Segmented Cathodes to Understand in-Plane Performance Variation on Anode-Supported SOFCs
Authors: Kim Min Woo , Kim Jung Myung , Park Hee Sung , Lim Hyung-Tae
Published: February 2020

In planar solid oxide fuel cells (SOFCs), in-plane electrochemical performance can be significantly varied, depending upon operating conditions such as current density and fuel/oxidant utilization, etc. In our previous study, anode-supported SOFCs were tested using four segmented cathodes under co-flow and counter-flow conditions. Even in the case of small size button cell, in-plane performance variation was not negligible under co-flow condition. A larger planar cell is expected to show more significant in-plane performance variation, with higher fuel utilization. In the present study, 5 x 5 cm2 cells were tested with four segmented cathodes to investigate in-plane performance variation as function of fuel utilization. Additionally, Pt reference electrode was embedded in the electrolyte layer of each segment. Utilizing three electrode system for each segment, anode and cathode overpotential can be separated for each segment so that the cause of in-plane performance variation can be more accurately analyzed. Experimental results were discussed with numerical analysis.
Nanoporous Aluminum Oxide Templates of Arbitrary Thickness on Silicon Carrier Wafer
Authors: Scisco Gibson , Skinner Anna , Hill Justin J , Jones Kevin Scott , Ziegler Kirk J
Published: February 2020

Porous templates of anodized aluminum oxide (AAO) are of interest in terms of photonics, energy storage, and other various nanoscience applications. There is a great interest to grow AAO templates directly on silicon as a carrier wafer, however most attempts rely on film deposition techniques that are generally suited for depositions on the order of 1 um. Thicker aluminum films are desirable in order to achieve better ordering of the AAO pores through two-step anodization and for greater aspect ratio for applications where surface area is the dominant factor such as solar cell and supercapacitor devices. Thick metal films are commonly applied through electrodeposition, however this technique is not suitable for aluminum owing to its high reduction potential above that of water. Aluminum and silicon are known to alloy up to approximately 1 atomic percent silicon in aluminum. Here, AlSi alloys are used as adhesion layers between aluminum foils and silicon wafers as a solution to the thin film problem. High purity aluminum foils and silicon wafers are pressed together as a diffusion couple. The couple is then annealed under argon atmosphere at temperatures from 550oC to 650oC (from below the AlSi eutectic temperature of 577oC to just below the Al melting temperature of 660oC) for various times. Cross sections of these couples are examined under scanning electron microscopy (SEM) to determine the thickness of the diffusion region and to check for the presence of voids. The chemical composition of the diffusion region is investigated through electron probe micro-analysis. Bonded Al-AlSi-Si composites are anodized in either phosphoric or sulfuric acids using a two-step process, and the final AAO morphology is examined under SEM.
Copper-Cobalt Spinel Nanostructures As Multifunctional Electrocatalysts
Authors: Nath Narayan Chandra Deb , Park Hyunwoong , Lee Jae-Joon
Published: February 2020

In recent years, the spinels, AB2X4 (A = divalent alkaline-earth and/or transition metal cations, B = trivalent group 13 elements and/or transition metals cations, and X = O, S, Se, Te, N, etc.) have attracted a great deal of research interest owing to their wide range of applications in conversion reactions, energy conversion, energy storage, data storage, biotechnology (magnetic sensing), electronics (spintronic devices) and laser devices. Their controllable composition, electronic structure, valence states or redox characteristics, morphology, and high catalytic property have made them suitable as catalysts in various conversion reactions such as oxygen evolution reaction, oxygen reduction reaction, hydrogen evolution reaction, alcohols oxidation, CO2 reduction, NH3 oxidation, H2O2 decomposition, urea oxidation, and methylene blue degradation. In addition, the high intrinsic electrical and excellent redox characteristics of spinels extended their applications into energy storage fields, such as supercapacitors and metal−ion batteries (such as Li-ion, Na-ion, Mg-ion Zn-ion batteries). Among the numerous varieties of spinels, CuCo2O4 is one of the most intriguing composite oxides, because of its high electrical conductivity, electrocatalytic activity, prominent Jahn–Teller effect and low toxicity. Herein, we report the multifunctional activities of CuCo2O4 toward water splitting, alcohol oxidation, H2O2 decomposition, urea oxidation, and energy-storage.
New Avenues to MOF Derived Cobalt Chalcogenides for Efficient Electrocatalysis
Authors: Das Debanjan , Nanda Karuna
Published: February 2020

Metal-organic frameworks (MOFs) have emerged as intriguing self-templates for fabricating a plethora of functional materials with excellent activity. Herein, we have developed three different routes useing cobalt imidazolate frameworks (ZIF-67) to design cobalt selenide (CoSe) hybridized with nitrogen doped carbon.

The solid-state strategy involves direct conversion of ZIF-67 into CoSe nanoparticles with an average size of 20-25 nm encapsulated within N-doped graphitic carbon shells with an average size of 300 nm. Interestingly, this method can easily be extended to similarly synthesize CoTe encapsulated N-doped graphitic carbon cages by simply changing the precursor.

The other method involved the self-templated conversion of ZIF-67 into Co nanoparticles encapsulated N-doped carbon polyhedral and their subsequent transformation into vertically aligned CoSe grafted N-doped carbon sheets via a hydrothermal selenization method. Both, these class of materials so synthesized were found to exhibit excellent electrocatalytic activity towards HER and OER in alkaline medium. It is believed that the methods being developed here may be extended to other transition metal chalcogenides for various applications

Figure 1
Binary Cobalt Manganese Oxide Systems for Electrocatalytic Applications
Authors: Chen Chun-Hu
Published: February 2020

In this presentation a redox-assisted approach in water will be demonstrated to produce binary cobalt manganese oxide electrocatalysts with high elemental homogeneity, improved conductivities, and durable stability. This talk will cover nanostructured particles and thin films of cobalt manganese oxides in applications of electrochemical biosensing and oxygen evolution reaction with over potentials as low as 0.30 V. The nanostructures in the cobalt manganese oxides can be controlled by varied reaction temperatures, strongly related to the hydrogen peroxide sensing performance. Highly continuous thin films can be depositd with ultrathin thickness (less than 10 nm) over large area (10 x 10 cm2) with simple manners. The thin films demonstrate strong adhesion on arbitrary substrates comprised of plastics, metals, ceramics, and woods with complex surface textures. Trinary metal oxide deposition can be successfully done to obtain novel thin film electrocatalysts. The film structures, redox reaction principle, and growth control mechanism will be also discussed. This redox approach represents an unprecedented, generic protocol in creating new multi-metal oxide electrocatalysts on diverse electrode surfaces.
(Invited) Shimshon Gottesfeld, the Right Person at the Right Time (Hydrogen: how we got here)
Authors: McCormick Byron
Published: February 2020

Fuel cells and hydrogen have long offered the promise of clean abundant energy from renewable resources with concepts like the Hydrogen Economy and Hydricity going back decades. We are now at the position where commercial vehicles and fuel stations are on the road as well as wide spread additional commercial applications like forklifts and stationary power. While the challenges for hydrogen and fuel cells aren’t over, it is obvious and clear that they will play a significant role in society’s energy system going forward and have attributes well suited for the changing energy landscape with their ability to shift energy across times, distances and energy sectors. This talk will focus on a historical perspective of the Los Alamos National Lab fuel cell program where the first publicly funded fuel cell for transportation research started that eventually enabled advances that allowed a technology only suitable for space applications to have terrestrial commercial viability. As the lead for Los Alamos efforts and later GM, I will pass along first-hand accounts of the early times in the development of the technology and institutional challenges we faced.
Shimshon Gottesfeld - a Pioneer of Fuel Cell Science and Catalyst of the Fuel Cell Community
Authors: Savinell R F.
Published: February 2020

Shimshon Gottesfeld has had a long and distinguished career in electrochemistry, and his work has been the foundation for modern PEM fuel cell development. He has also lead the initiate to establish a Gordon Research Conference on Fuel Cells and chaired the first conference in 1999. My talk will focus on his early work in electrochemistry and how it transformed the understanding and development of PEM fuel cells, and how it impacted the early work we did not high temperature membrane fuel cells. And, I will also describe the culture of the early Fuel Cell GRCs, which has left an indelible mark on memories of many of us.
(Invited) The Impact of Work By Dr. Gottesfeld and Coworkers on the Commercial Introduction of the Fuel Cell Vehicle -- Calling the Shots in Polymer Electrolyte Fuel Cells
Authors: Mathias Mark F
Published: February 2020

Dr. Gottesfeld’s entire career has been characterized by developing early stage fuel cell technology using fundamental science and practical engineering intuition and analysis. It is unusual to see fundamental electrochemistry expertise coupled with electrochemical engineering intuition and skills in the same person. This combination has enabled him and his coworkers to identify controlling phenomena that have proven to be focal points for development and the critical points that determine the ultimate capability of the technology and its application outcome. Furthermore, his dedication and passion in these areas guide and inspire the next generation of contributors across four distinct fuel cell families.

In this talk, I will describe how this pairing of fundamental and device level intuition from the group that he led at Los Alamos National Lab (LANL) from 1987-2000 impacted the development of proton exchange membrane fuel cells from initial development stages to readiness for automotive market introduction. For example, the pathway for the reduction of precious metal loadings to commercially viable levels was initially defined by experiments and fundamental models from the LANL group. The LANL work on membrane water transport was critical to understanding why thinner membranes offered performance benefits beyond their ionic resistance impact. Even the contemporary R&D work to push to high current density (>2 A/cm2) for the sake of reduction of fuel cell area is informed by initial LANL developments as well as Dr. Gottesfeld’s work (published in 2008) on the impact of the Pt-oxides on oxygen reduction kinetics. More broadly, this body of work reminds us that the pathway to push any fuel cell technology to its best possible outcome is to systematically apply coupled experiments and models in order to identify and focus R&D attention on the rate processes that are “calling the shots”.
(Invited) Progress Towards High Power Density and Durable PEFCs with PGM-Free Cathodes
Authors: Uddin Md. Aman , Langhorst Lisa , Zhang Hanguang , Guo Yuqi , Xu Xiaomin , Beltran Diana , Wu Gang , Litster Shawn
Published: February 2020

This presentation will highlight recent advances in achieving high power density with polymer electrolyte fuel cells (PEFCs) that use platinum-group metal-free (PGM-free) catalysts for the cathode’s oxygen reduction reaction (ORR). PGM-free catalysts have the potential to radically reduce the cost of manufacturing PEFC cathodes. However, several technical challenges with PGM-free cathodes need to be addressed, including a need for increased catalyst activity and stability as well as improved catalyst integration into MEAs for higher power density and better durability. Electrode engineering is crucial to achieving high performance with PGM-free catalysts because the lower volumetric activity yields thicker electrodes that cause significant water flooding and large oxygen and proton transport losses. This talk will highlight recent advances in the field as well as our own recent achievements with PGM-free catalysts prepared from chemically-doped metal organic framework (MOF) precursors. The focus of the talk will be on the electrode integration of these catalysts, including a systematic optimization of the catalyst morphology for MEA integration that leverages the ability to carefully tune the size of the MOF-derived catalyst’s primary particles. A key aspect of our study was the control of particle morphology for effective ionomer distribution. Through combined computational simulation, experimental fuel cell characterization, and electron and high resolution X-ray imaging, we show the significant performance improvements that can be achieved. Furthermore, we present the current status of the MEA durability and will discuss current hypotheses regarding the degradation mechanisms and possible mitigation strategies.

The authors gratefully acknowledge research support from the Electrocatalysis Consortium (ElectroCat), established as part of the Energy Materials Network under the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, under Contract Number DE-EE0008076.
(Invited) Translating Knowledge from PEM and AEM Fuel Cells to Biofuel Cells and Hybrid Fuel Cells
Authors: Minteer Shelley D.
Published: February 2020

Early biofuel cells were designed after polymer electrolyte membrane (PEM) fuel cells using Nafion as a separator between the bioanode and the biocathode. This talk will discuss how the knowledge of PEM fuel cells has been used in biofuel cells and the special issues of biofuel cells that have made translating knowledge to devices difficult. After discussing the issues with using Nafion in a biofuel cell, the talk will focus on the new expanding area of alkaline exchange membrane fuel cells and the ability to translate that knowledge to biofuel cells, hybrid fuel cells, and redox flow biobatteries. Discussion will include the struggles of using either an acidic or basic membrane in a near neutral pH regime, as well as a discussion of device design principles.
(Invited) Limits of Polymer Electrolyte Membranes
Authors: Mittelsteadt Cortney
Published: February 2020

Since their introduction in the 1960’s polymer electrolyte membranes, PEMS, for fuel cells have been extensively studied. Hundreds if not thousands of polymer systems have been synthesized and characterized to improve the critical properties of conductivity, chemical and mechanical durability as well as the lesser important properties of water and gas transport.

It is well accepted that these properties are highly dependent on the chemistry of the polymer electrolyte backbone as well as the functional groups and how they organize on the molecular scale. Many models have been used to frame these properties to fit experimental data. What is done less-often is to use the models to then establish the limits of these.

Using the conductivity of their small-molecule analogies, triflic acid for PFSA’s and benzene sulfonic acid for hydrocarbons we set limits on conductivity and permeability. Finally we will also look at how the two most common strategies of increasing PEM performance; increasing charge density and acid strength, are limited by mechanical and chemical durability requirements, respectively.
(Invited) Quantitative Understanding of CO2 Behavior in Anion Exchange Membrane Fuel Cells
Authors: Zheng Yiwei , Peng Xiong , Mustain William E.
Published: February 2020

The past two years have seen a tremendous enhancement in the performance and durability of anion exchange membrane fuel cells (AEMFCs) [1-2]. Multiple AEMFCs have been reported that can achieve 1.5-2.0 W/cm2 peak power, limiting current > 5 A/cm2 and >500 hour operation almost negligible voltage decay. These operation metrics suggest that AEMFCs are well on their way to competing with proton exchange membrane fuel cells (PEMFCs) in terms of performance, with the additional possible benefit of being lower cost. However, one limitation of all of this work is that it has been done with purified O2 or air fed to the cathode in order to avoid exposing the electrolyte to CO2, which leads to carbonation and a loss of cell performance. Most researchers believe that electrolyte carbonation simply leads to a loss of ionic conductivity, but we will show in this presentation that conductivity loss alone is only able to explain ~10% of the voltage loss once the CO2 is fed to the cathode, suggesting a different mechanism that will be explained.

It has also been recently shown theoretically [3] that the level of carbonation in the AEMFC will be a function of the CO2 concentration and current density as the “self-purging” mechanism [4] acts to remove carbonates as they are formed. However, this behavior has not been confirmed experimentally and the carbonation dynamics are poorly understood. This presentation will present an extensive collection of carbonation data as a function of current density and CO2 concentration at the cathode. We will also link the level of carbonation to electrochemical performance, discuss the lower limits for CO2 tolerance in AEMFCs and discuss strategies to reduce make cells more tolerant to cathode CO2.

Finally, one of the most critical items that has been overlooked in AEMFCS to date is the operation of realistic systems where the anode flowrate is preferably very low. In PEMFC systems, the low anode flowrate results in N2 accumulation on that side of the cell from diffusion. In AEMFCs, not only will this happen, but CO2 will accumulate on the anode side of the cell under operation on real air. This means that anodes will operate under very high relative humidity and very high CO2 concentration conditions. Therefore, the final topic discussed in this presentation will be the influence of accumulated anode CO2 on AEMFC performance.

References

Mustain, Current Opinion in Electrochemistry, DOI: 10.1016/j.coelec.2018.11.010

Maurya, S. Noh, I. Matanovic, E.J. Park, C.N. Villarrubia, U. Martinez, J. Han, C. Bae and Y.S. Kim, Energy Environ. Sci., DOI:10.1039/C8EE02192A

Krewer, C. Weinzierl, N. Ziv and D.R. Dekel, Electrochim. Acta, 263 (2018) 433-446.

Ziv, W.E. Mustain and D.D. Dekel, ChemSusChem, 11 (2018) 1136-1150
(Invited) Water and Thermal Management in Polymer-Electrolyte Fuel Cells
Authors: Weber Adam Z.
Published: February 2020

Cost and durability of polymer electrolyte fuel cells (PEFCs) remain the major hurdles in way of their commercialization. To optimize cell performance and understand degradation mechanisms, mathematical modeling provides an ideal framework. The need to drive towards high power density and thus reduce stack count and cost required optimizing the mass transport and related phenomena within the PEFC. For proton PEFCs, such mass transport is dominated by transport of oxygen molecules to the reaction site within the catalyst layer. For hydroxide PEFCs, additional transport limitations including hydroxide ions and perhaps even hydrogen can become important. In addition, transport phenomena in both cells are hindered by multiphase flow phenomena due to the lower operating temperatures and need for membrane humidification. In this talk, we will explore the limiting transport mechanisms and effects through mathematical modeling and advanced diagnostics.
The Use of a Protein Scaffold to Control the Structure of Electrodes and Ionomer in Proton Exchange Membrane Electrolyzers
Authors: Pramounmat Nuttanit , Kim ChulOong , Renner Julie
Published: February 2020

Among the frontrunners of hydrogen production technology, proton exchange membrane (PEM) electrolysis is safe, simple, and highly efficient. PEM electrolysis has ability to be integrated in a variety of energy systems and infrastructures such as transportation, renewable electricity, biogas upgrading, as well as ability to address seasonal-variation in long timescales. One of the major challenges that remains is the high cost of noble-metal catalysts in the membrane electrode assembly (MEA). Recent attempts in research and development are directed toward low-loading of platinum group metals.

We engineered a synthetic protein to improve platinum catalyst utilization in the MEA, and control ionomer-catalyst interfaces. The multifunctional protein is engineered to direct ionomer (the electrolyte) towards platinum active sites. With the protein added to catalyst layer, the nanostructure and phase separation were examined and compared with a conventional catalyst layer. The engineered protein additive results in distinct structural changes in the electrode. This work yields a promising model for controlling ionomer catalyst interactions, and could lead low platinum group metal PEM electrolyzers.
Evaluation of Respiratory Activity IMAGE in Normal Human Epidermal Keratinocyte SHEET Using BIO-LSI
Authors: Kasai Shigenobu , Sato Teruya , Prasad Ankush , Inoue Kumi Y. , Ino Kosuke , Shiku Hitoshi , Matsue Tomokazu
Published: February 2020

Cell sheets have been studied for the purpose of regenerating dysfunctional tissues and it has also been reported that systemic transplantation of autologous cultured epidermis was actually successful. However, there are few simple methods for testing activity after cell sheet preparation. In this study, we aimed to reproduce the state of sunburn on a part of normal human epidermal keratinocyte sheet by UV irradiation and to evaluate the activity using Bio-LSI. The evaluation examined the respiratory bursts in immune cells by monitoring in real-time, the O2 consumption of the epidermal cell sheet. The cell sheet culture kit Lab Cyte EPI-KIT (Japan Tissue Engineering Co., Ltd.) was cultured for 18 days and were cut into a circle of about 5 mm in diameter. The cell sheet was then covered with a mask leaving 1mm × 1mm open surface for irradiation with UV light (365 nm wavelength and an illuminance of 300 mW/cm2 for 10 seconds). Following UV irradiation, it was installed in the measuring device promptly. The experimental conditions were as mentioned below: measurement solution: 11.4 mM glucose in PBS; W.E.: Pt electrode (d= 40 um) ×400 point; R.E.: Ag/AgCl electrode; C.E.: Pt wire; applied voltage: -0.5 V vs. Ag/AgCl and sampling time: 500 ms. In Fig. 3, it can be seen that the area of cell sheet illuminated with UV irradiation shown lower oxygen concentration (reflected by black area) while non-irradiated parts show higher oxygen level. It is due to the fact that UV exposed cells suddenly consumed oxygen.

References:

1) G.G.Gallico III, N.E.O'Connor, C.C.Compton, O.Kehinde, H.Green. (1984). New England Journal of Medicine, 311(7), 448-451.

2) J.G.Rheinwald. (1980). Methods in cell biology (Vol. 21, pp. 229-254). Academic Press.

3) H.Kikuchi, A.Prasad, R.Matsuoka, S.Aoyagi, T.Matsue, S.Kasai. (2016). Frontiers in physiology, 7, 25.

Figure 1
Evaluation of Respiration Activity for Diagnosis of Mastitis Using SECM
Authors: Kasai Shigenobu , Kumagai Ryoma , Prasad Ankush , Honmo Tomohiro , Kumagai Masashi
Published: February 2020

1. Introduction

Mastitis is a generic term for biological reactions leading to damage of mammary gland tissue, which occurs when intestinal microbes invade into mammary glands. Currently, Somatic cell count (SCC)1) is widely used as mastitis diagnosis method utilizing the fact that a large number of somatic cells are present in the milk of mastitis cattle. However, early diagnosis is difficult with this method. We have evaluated respiratory activity and respiratory burst of immune cells by Scanning electrochemical microscopy (SECM)2). In this study, attention was paid to the fact that neutrophils are particularly likely to increase among somatic cells, and evaluation of respiratory activity can be used as a marker for the diagnosis of mastitis.

2. Experiment

2.1 Type of milk sample used

Two milk samples were obtained from Holstein cows. The somatic cell count of each of the two samples was 211 × 105 cells / mL and 31 × 105 cells / mL.

2.2 Evaluation of respiration activity for the somatic cell in milk method

2μL of the sample was put into the inverted conical well and was incubated at 37 °C for 15 minutes. Following this step, 10 mL of phosphate buffered saline (PBS) containing 11.4 mM glucose was added into the well. An Ag/AgCl electrode and a Pt electrode (d=20μm) were installed. The Pt electrode was scanned in the Z direction at the center of the well with the sample (Fig.1). Oxygen concentration profile was monitored by applying -0.5 Vvs.Ag/AgCl using SECM and scanning 500 μm in the vicinity of the sample. The scanning speed was 10 μm/s, the number of scans was kept at 3 with a sampling interval was 100 msec.

3.Results and Discussion

As shown in Fig. 2, differences in reduction current value were obtained. The average reduction current (where n=3) for ΔIr was observed to be -630pA while for ΔIb, it was found to be lower, reflecting a change in reduction current value of -400 pA. The difference observed in two different densities of cell lines shows a strong correlation between the number of somatic cells and its relation to changes in reduction current. It is thus proposed that the monitoring of respiratory burst can serve as a method for early diagnosis and detection of mastitis.

Acknowledgement

We would like to thank Kakuda farm that provided us with milk samples and for their excellent cooperation during the course of study.

References

1) M. Damm, et al., J.Dairy Sci.100:4926-4940,2017

2) H. Kikuchi, et al.,frontiers vol.7 Article25 2016

Figure 1
Development of Electrochemical Nanosensor for the Detection of Malaria Parasite in Clinical Samples
Authors: Obisesan Olaoluwa R. , Adekunle Abolanle Saheed , Oyekunle John A.O. , Thomas Sabu
Published: February 2020

In this study, Metal oxide nanoparticles (MO = CuO, Fe2O3, Al2O3) synthesized by chemical (C) and microwave (M) methods were used for sensor development and characterized. Electrochemical nanosensors were developed from the synthesized metal oxide (MO) nanoparticles by supporting it on a gold electrode (Au). The fabricated sensors were characterized, and their sensing behavior was determined using cyclic voltammetry and square wave voltammetry techniques. The activity of the developed nanosensor towards the detection of malaria biomarker (β-hematin) was determined and the optimum conditions at which the maximum detection and quantification occurred was established. β-Hematin current response at the sensors was higher compared with the bare Au electrode and followed the order Au-CuO (C) > Au-CuO (M) > Au-Fe₂O₃ (M) > Au-Fe₂O₃ (C) > Au-Al₂O₃ (M) > Au-Al₂O₃ (C) > bare Au. The developed sensors were stable with a relatively low current drop (10.61 - 17.35 %) in the analyte. This study demonstrated that electrocatalysis of β-hematin was more favored on Au-electrode modified with CuO nanoparticles (chemical and microwave synthesized). The outstanding properties of the Au-CuO electrodes over others include enhanced current response at lower onset potential for catalysis, high electrochemical stability in the analytes (resistance to electrode fouling) and good signal separation between malaria and Salmonella typhi antiserum (i.e little or no interference) during detection. Au-CuO sensor has the best performance towards the biomarker and quantitatively detected P. berghei in infected mice’s serum samples at 3.60 – 4.8 mM and P. falciparum in human blood serum samples at 0.65 – 1.35 mM concentration. The developed sensor successful separated β-hematin from Salmonella typhi antiserum with well-defined signal separation of 250 mV.
Combined Electrokinetic and Electrochemical Measurements to Study the Electric Double Layer at Electrode-Electrolyte Interface
Authors: Saha Prantik , Truong Amber , Nam Changwoo , Hickner Michael , Zenyuk Iryna V.
Published: February 2020

Electrochemical techniques, such as cyclic voltammetry and chronoamperometry are generally used to understand the reaction kinetics and structure of the electric double layer (EDL) formed at the electrode-electrolyte interface. While these techniques can effectively probe the Faradaic reactions, specific adsorption processes etc., they are limited in their applicability towards measuring potential at the outer Helmholtz plane (OHP). On the other hand, electrokinetic methods are broadly used to measure potential at the slip plane, Zeta potential, which determines the nature of the diffuse layer at the interface. Depending on the ionic strength of the solution (Debye length) Zeta potential and OHP potentials can coincide. In this study, we used the electrokinetic techniques, such as streaming-current and streaming-potential methods to measure Zeta potential of solid metallic surfaces and hence attempted to bridge electrochemical and electrokinetcs in understanding of the EDLs.

Figure 1a shows a novel electrochemical cell designed by our group and adapted for the electrokinetic set-up. In conventional streaming current experiment, pressure difference between the two electrolyte reservoirs drive the ionic current mostly through the slip plane. By taking the slope of current vs pressure at a given pH a Zeta potential can be calculated. We report Zeta potential of a strip of Au, our model electrode, under various conditions (varied pH and electrolyte concentration), where the solid cell set-up measurements were validated against the more conventional Zeta potential measurements of colloidal particles with dynamic light scattering approach. By incorporating electrochemical set-up, we were able to vary applied potential on the electrode to probe potential of zero charge (pzc) of gold. The surface of gold electrode was cleaned beforehand in electrochemical three-electrode set-up using cycling voltammetry. Combining the data obtained from cyclic voltammetry and electrokinetics and applying the well-tested Gouy-Chapman theory of the EDLs, we were able to calculate the ion-distribution in the diffuse layer, the diffuse layer conductivity and the charge density on the surface of the electrode. We also attempted to comment on the possible relationship between the pzc and iso-electric point. The pzc of gold was found to be dependent on the pH of the electrolyte, and it varied between 200 mV to 500 mV on SHE. Next, we will extend the method to the other interfaces of interest to electrochemical community (such as Pt).

Figure 1
Piezoelectric Electric Supports Modulate the Reactivity of Platinum Thin Films
Authors: Counihan Michael John , Simpson Burton H , Rodriguez-Lopez Joaquin
Published: February 2020

The oxygen reduction reaction (ORR) is at the heart of many renewable energy technologies. This kinetically slow reaction requires large overpotentials even on the best catalysts like platinum and its alloys. Numerous studies have employed strained platinum surfaces to change oxygen adsorbate binding energies and lower the ORR overpotential, though strain is often convoluted with electronic effects from alloying with other metals. Additionally, discrete samples offer only one static strain condition, making testing of multiple surface configurations costly. We present a piezoelectric platform capable of generating dynamic strain on thin film platinum catalysts without unwanted electronic effects due to alloying. Application of various voltages to an interdigitated array on the piezoelectric drives the mechanical deformation of the platinum thin film, resulting in significant increases in ORR activity and up to 10 mV lower overpotentials. The applied mechanical strain is reversible, and reactivity changes are not resultant from electronic communication between the piezoelectric and electrode, temperature increases, or local field effects. This new analytical platform opens new opportunities for studying strain effects in electrocatalysis.
Effect of Capping-Agents on Performance of Copper Nickel Tin Sulfide (CNTS) Nanocrystals Based Solar Cells
Authors: Haram Santosh Krishna , Jadhav Yogesh
Published: February 2020

In recent years, colloidal semiconductor nanocrystals based solar cells have achieved photo-conversion efficiency closed to 12% which has triggered renewed interest to undertake fundamental investigation on these materials. Among many prospective candidates, quaternary chalcogenides viz. Copper Zinc Tin Sulfide/Selenides (CZTS) and its analogs have been tested extensively due to its high absorption coefficient near 1.1-1.5eV, low elemental cost, non-toxic nature and ability to form alloy structures, without apparent phase segregation. All these characteristics make them very attractive candidate to investigate them for solar cell applications. Their composition dependent band-edge parameters give further opportunity to form tandem heterojunction devices which would absorb broad spectrum of light and give the possibility to push the performance towards betterment. In many such investigation the capping agents used in the preparation of nanocrystals have assumed to be mute candidate in performance of the solar cells. However, our preliminary investigation on copper nickel tin sulfide (CNTS) nanocrystals based solar cell revealed that the nature of capping agents is also an important parameter and impact the solar cell performance. Herein, we report the preparation of CNTS nanocrystals and demonstrated the effect of capping agents on the performance of solar cells. To prepare CNTS nanocrystals, hot-injection method have been used. Two variants have been prepared by varying capping agents; long-chain oleylamine capped CNTS (OLA-CNTS) and short chain Mercaptopropionic acid (MPA) capped CNTS (MPA-CNTS). These were well characterized by UV-Vis-NIR, XRD, Raman, AFM, TEM, FESEM, and EDAX. All these characterizations confirm the formation single phase CNTS. Cyclic voltammetry investigation have been performed on CNTS nanocrystals to estimate the conduction and valence band edge parameters as a function of composition. For the first time, CNTS liquid junction solar cell with an architecture; FTO/TiO2/CdS-CNTS/ZnS/S-/Sn--/CuS/Se/FTO have been prepared. Solar cell prepared out of OLA-CNTS gave very poor power conversion efficiency. While, similar solar cell constructed out of MPA-CNTS displayed better performance having the efficiency and the fill factor in the order of 1.25 % and 0.380, respectively. Furthermore, an electrochemical impedance spectroscopy (EES) measurements revealed that MPA-CNTS has relatively low charge transfer resistance than OLA-CNTS. This property has been attributed to the poor performance of OLA-CNTS. Further investigations to optimize this material and device architecture would expected to increase the efficiency.

Figure 1
(Invited) Engineering of Enzymatic Bioelectrochemical Interface for In Vivo Analysis
Authors: Wu Fei , Mao Lanqun
Published: February 2020

Bioelectrocatalysts have enabled a rapid development of sensing methods and devices for in vivo quantification of chemical species, which is crucial for understanding the molecular basis of life. However, these sophisticated functional units face a set of challenges when operated in vivo. One inevitable issue is the kinetic barrier for heterogeneous electron transfer at the electrode-enzyme interface, especially when direct electron transfer (DET) is preferred as toxic and unstable mediators are not suitable for in vivo applications. Different strategies have been explored to improve DET efficiency, and lately, a new method for regulating the molecular orientation of laccase on single-walled carbon nanotubes was developed based on the principle of surface wetting. Electrochemical and vibrational spectroscopic investigation drew a mechanistic picture of how enzymes behave in the presence of wetting reagents (such as ethanol), offering a new guidance for the design of bioelectrochemical interfaces.

Another issue associated with in vivo biosensing rises from interference of intrinsically existing substrates (other than the analytes) for enzymes, e.g., oxygen and NAD+ that function as electron acceptors for commonly employed oxidases and dehydrogenases. In our recent studies, we have explored a new enzyme candidate, ferredoxin-dependent glutamate synthase (Fd-GltS), as a bioelectrocatalyst. Containing multiple redox centers, Fd-GltS can be fined tuned with various mediators to enable either bioelectrosynthsis of glutamate or bioelectrochemical oxidation of glutamate. By this means, we can construct a new bioelectrochemical interface devoid of oxygen and cofactor interference, thus providing a new option for the development of biosensing platform for glutamate-mediated neurotransmission.
Heavy Metals Extaction and Separation By Electrodeposition on a STEEL Substrate from Wastewater
Authors: Addi Yassine
Published: February 2020

Heavy metals contaminated waste water sludge is classified as hazardous solid waste (1). For this reason it needs to be properly treated to prevent releasing heavy metals to the environment.

The sludge was treated in a batch reactor (2) by sulfuric acid to extract the contained heavy metals (Cu; Cd; Ni and Zn).

The effects of sulfuric acid concentration and solid to liquid ratio on the heavy metal removal efficiencies were investigated. The experimental results showed that the total and individual heavy metal removal efficiencies increased with increasing sulfuric acid concentration, but decreased with increasing solid to liquid ratio.

For 5g/L solid to liquid ratio, more than 99,9% of heavy metals can be removed from the sludge by treating with 0,5 M sulfuric acid in 2h.

The separation, of metals extracted by sulfuric acid from the sludge, is carried out by plating on steel substrate (3).

References;

(1) B.Johnke. B.Wiebusch, Fuel Energy Abstract.1997. 38. 350

(2) M.A.Styllanou; D.Kollia,K.J.Haralambous. V.J.Inglezaki. ,K.G.Moustakas. M.D.Loizidou, Desalination
2007. 215. 73-81

(3) Mortaga M.Abou-Krisha, Applied surface science
2005. 252. 1035-10480