bluuebunny/crossref_metadata_2025 huggingface dataset:
Modifying Crystal Symmetry and B-O Charge Distribution to Tailor Chemical Expansion in Mixed Conducting Perovskites
Authors: Anderson Lawrence O. , Yong Adrian Xiao Bin , Ertekin Elif , Perry Nicola H
Published: July 2022

The exchange of ions between a lattice and the gaseous phase makes mixed conducting oxides ideal for a range of electrochemical applications. Altering oxygen ion concentration is accompanied by a change to electronic species concentrations, and this influences electrical, chemical, kinetic, and mechanical properties. The stability of electrochemical devices like fuel cells and batteries can heavily rely on the mechanical response to changes in chemical defect concentrations. Under both dynamic and steady-state operation of these devices, large volume strains and strain mismatch at interfaces can result in fracture, warping, and delamination that can cause performance degradation and/or failure. Strains between different materials are compared using the coefficient of chemical expansion (CCE), which normalizes the isothermal chemical strain by the change in defect concentration. Here, we advance the understanding of chemo-mechanical coupling through the study of PrGa0.9Mg0.1O3-δ and BaPr0.9Y0.1O3-δ by demonstrating CCEs 2-5x lower than any previously reported perovskite oxide1.

Isothermal CCEs were evaluated with in situ, high temperature, and variable atmosphere x-ray diffraction and dilatometry for chemical strains, and with thermogravimetric analysis for stoichiometry changes. The experimental results show chemical strains to be significantly lower than predictions from simple empirical models that assume pseudo-cubic structures and full charge localization on multivalent cations, like Pr. To evaluate actual charge distribution, in situ impedance spectroscopy and density functional theory calculations were performed. The collaboration of experimental and computational work combines accurate and reliable material characterization with insights into atomic and electronic structures that are difficult to probe experimentally.

Our results for the studied compositions indicate 2 primary factors that can be used to modify CCEs: 1) Altering the crystal structure away from the isotropic, cubic phase encourages anistropic expansion and lower CCEs in polycrystalline materials, and 2) Varying the distribution of charge along B-O bonds is shown to dramatically alter the CCE. While the first factor provides rather clear guidance to tailor expansion, we elaborate on the second by suggesting band structure design principles for near-zero redox-strain perovskites, and the benefit of locating holes partially or fully on oxygen is highlighted. These new findings add to the growing collection of crystal-chemical design rules for the rational tailoring of chemo-mechanical coupling in perovskite oxides.

(1) Anderson, L. O.; Yong, A. X. Bin; Ertekin, E.; Perry, N. H. Toward Zero-Strain Mixed Conductors: Anomalously Low Redox Coefficients of Chemical Expansion in Praseodymium-Oxide Perovskites. Chem. Mater.
2021, 33 (21), 8378–8393. https://doi.org/10.1021/ACS.CHEMMATER.1C02739.
(Invited) Electro-Chemo-Mechanics at Solid Electrolyte-Cathode Interfaces
Authors: Yildiz Bilge , Kim Younggyu , Zguns Pjots
Published: July 2022

Strain is present at interfaces of solid electrolytes with cathode and anode in solid state batteries due to interfacial reactions and due to volumetric expansion and contraction of the electrodes during battery charge and discharge cycles. In this talk, first, I will present our findings on how a solid electrolyte-cathode interface degrades chemically and electrochemically, and its implications on the interface mechanical degradation. In particular, we have studied the garnet type Li7La3Zr2O12 (LLZO) solid electrolyte with thin film LiNi0.6Mn0.2Co0.2O2 (NMC622) cathode as a model system to enable interface sensitivity. X-ray absorption spectroscopy, X-ray diffraction and Gibbs free energy analysis have enabled us to identify the chemical and electrochemical degradation pathways, and their implication on the mechanical instability at the interface. Second, is the reverse effect of such mechanical evolution, in particular the effect of elastic strain at the interface on Li-ion diffusion in the solid electrolyte. For this question, we have taken a model solid electrolyte, β-Li3PS4, and have performed Ab Initio Molecular Dynamics (AIMD) simulations to resolve the resulting changes in Li site stability and Li ion conductivity under different strain tensors. We have found that the strain tensors which compress the c-axis (+2% ab, –2% ac, –2% bc, –2% isotropic) increase the Li-ion diffusivity, and the strain tensors which stretch the c-axis (–2% ab, +2% ac, +2% bc, +2% isotropic) reduce it. The c-axis compression increases disorder in the lattice and promote jumps along all migration pathways. The results show that elastic strain can promote Li disorder and superionic conductivity, with an effect on Li-ion diffusion comparable to that of chemical doping, and is important to consider for accurate understanding and prediction of solid-state Li-ion battery interface properties.
Understanding Coupled Electro-Chemo-Mechanics during I
n Situ Li Metal Anode Formation in Anode-Free Solid-State Batteries
Authors: Kazyak Eric , Yadavalli Srinivas , Lee Kiwoong , Wang Michael , Sanchez Adrian J. , Thouless M.D. , Sakamoto Jeff , Dasgupta Neil P.
Published: July 2022

Solid-state batteries (SSBs) are potentially disruptive for a range of applications owing to their promise of high energy density, improved safety, and long cycle life. Their ability to enable Li metal anodes is a major advantage for energy density, but Li presents challenges for manufacturing due to its reactivity and the difficulty of fabricating thin Li films and high-quality Li/Electrolyte interfaces. Recently, in situ anode formation has shown significant promise for overcoming these challenges. In this approach, the cells are assembled without an anode (“Anode-free”), and Li metal is plated out from the cathode after fabrication. This reduces the need for inert atmospheres and reduces cell complexity, potentially lowering cost.

As Li is plated out for the first time, mechanical stresses evolve at the Li/Electrolyte interface due to the volumetric changes in the electrodes. These stresses and the coupling between mechanics and electrochemistry play an important role in the resulting uniformity and quality of the in situ formed Li electrode. This work leverages 3D operandooptical video microscopy to observe morphology changes during in situ anode formation on one of the most promising solid electrolytes, Li7La3Zr2O12 (LLZO). These morphology changes are linked to the electrochemical signatures and the dynamic evolution of mechanical stresses at the Li/LLZO interface. A mechanistic framework is built to understand these factors, which is then used to provide guidance on what parameters control uniformity, and how systems can be designed to improve the resulting electrode properties. The role of stack pressure and the importance of stack pressure uniformity is highlighted. The impact of interfacial toughness, current collector properties, and cell geometry are discussed. Based on this understanding, the areal Li coverage is improved by more than 50%, providing insight for future works to enable in situ anode formation in a range of material systems and cell architectures.
(Invited, Digital Presentation) Transport Characterization in Nano and Micron-Sized Multi-Component and Multi-Functional Materials
Authors: Haussener Sophia
Published: July 2022

Porous and heterogeneous materials are core components in energy conversion and storage devices such as batteries, fuel cells and electrolyzers, or photoelectrochemical fuel generators. The heterogeneity and structural complexity of: i) the multi-functional nature of the applications requiring the presence of various functional materials in close vicinity, ii) nano- and micron-scale structuring of the material required to overcome the bulk material transport limitations, and iii) cheap and simple synthesis methods resulting in stochastic and complex morphologies. Understanding of the multi-physical transport phenomena and optimization of the component for enhanced performance, requires an accurate modelling and prediction of the transport properties, which heavily rely on the complex nano to micron-scale morphology.

In this presentation, I will show how tomography-based direct numerical simulation scan be used for the accurate numerical characterization of the heterogeneous components’ transport properties. We will use X-ray micro-tomography for the characterization of the (thermal) transport in partially saturated gas diffusion layers/electrodes or in porous thermochemical reactors, and FIB-SEM nano-tomography for the multi-physical transport characterization of photoelectordes for water splitting and catalyst layers of CO2 reducing gas diffusion electrodes. I will show how we have built up a digital library of (photo)electrodes. Furthermore, I will show how machine learning approaches can be used to guide the design of optimized structures.
(Invited) A Macro-to-Nano Zoom through the Hierarchy of a Lithium Ion Battery
Authors: Liu Yijin
Published: July 2022

Lithium-ion battery (LIB) is featured by structural and chemical complexities across a broad range of length scales and, ultimately, it is the hierarchy of the battery structure that determines its functionality. The study of the battery function, degradation, and failure mechanisms requires a thorough and systematic investigation from the structural, chemical, mechanical, and dynamic perspectives. X-ray-based characterization techniques are playing an important role in this research field.

In this talk, I will review my group’s research activities over the past few years [1-10] by presenting a macro-to-nano zoom through the hierarchy of a standard battery cell [2] using a suite of state-of-the-art X-ray techniques. Damage [6-7], deformation, compositional [9-10] and chemical [1, 4-5] heterogeneity at different length scales are visualized and are associated to different degradation phenomena and mechanisms. Our results highlight the importance of the battery cathode material’s mechanical properties [7-8], which evolve upon battery cycling and could significantly impact both the immediate and the long-term cell behaviours. Statistical analysis, numerical modelling [4], and machine learning [3, 5-6] approaches are key components integrated in our research efforts and will be touched upon in this presentation. I hope this presentation will ignite enthusiasm and ideas for future collaborations.

References:

(1) J. Zhang et al., Nat. Commun. 11 (2020) 6342.

(2) G. Zan et al., J. Mater. Chem. A (2021) DOI: 10.1039/D1TA02262H.

(3) Z. Jiang et al., Nat. Commun. 11 (2020) 2310.

(4) S. Li et al., Nat. Commun. 11 (2020) 4433.

(5) G. Qian et al., ACS Energy Lett. 6 (2021) 687–693.

(6) Y. Mao et al., Adv. Func. Mater. (2019) 1900247.

(7) S. Xia et al., Nano Energy 53 (2018) 753-762.

(8) C. Wei et al., Acc. Chem. Res. 51 (2018) 2484-2492.

(9) J.-N. Zhang et al., Nat. Energy 4 (2019) 594–603.

(10) F. Lin et al., Nat. Energy 1 (2016) 15004.
(Invited) Opportunities for Bulk Silicon As a High Capacity Lithium Host
Authors: Love Corey T. , Lefler Matthew J , Rudolf Chris , Yeom Junghoon
Published: July 2022

Silicon, the earth’s second most abundant element ushered in new age of computing capability. More recently, silicon is enjoying a second wave of technological adoption as a constituent of lithium-ion battery negative electrodes; made possible in practice by reducing the dimensions to the nanoscale and/or compositing with traditional carbon-based lithium host materials. The large lithium capacity and subsequent volumetric expansion and mechanical fracture have been documented extensively and the nano and composite routes mentioned above provide strategies to overcome this obstacle. We take a new exploratory approach elevating the working temperature to demonstrate reversible alloying and dealloying of lithium and silicon, in its most basic bulk form, a wafer. The brittle nature of silicon may be made more elastic when operated above its brittle-to-ductile transition temperature, potentially leading to more elastic behavior capable of maintaining its structure with modulation of its volume. Here was explore lithium alloying/dealloying into bulk silicon at elevated temperature to assess the efficiently and reversibility of silicon in this environment. While a contrived experiment, we are learning more about lithium diffusion into silicon and may provide a thermal preconditioning of silicon electrode materials to support long cycle for lithium-ion batteries. Additionally, the developmental improvements of a high temperature electrochemical cell will be conveyed along with demonstration of an electrolyte salt, LiTFI, in the molten form. Last, micro computed tomography 3D images will be presented to show crack formation and progression when alloying a bulk silicon wafer with lithium at elevated temperatures.
(Invited) Potentiometric Entropy and Operando Calorimetric Measurements to Assess the Performance of Heterogeneous Lithium Ion Battery Electrodes
Authors: Pilon Laurent
Published: July 2022

This talk presents new efforts to use potentiometric entropy and operando isothermal calorimetric measurements to gain insight into the charging mechanisms as well as the thermodynamics and ion transport in lithium ion battery electrodes. Electrodes consisted of particles of different sizes - from a few nanometers to a few microns - synthesized by solid state or sol gel methods and using different conducting polymer binders. Promising battery materials such as lithium sodium vanadium fluorophosphate LixNa1.5-xVOPO4F0.5, tungsten vanadium oxide (W0.2V0.8)3O7, and titanium niobium oxide Ti2Nb2O9 were considered. The effect of particle size and binder on the specific capacity, polarization, thermodynamic behavior, and lithium transport were investigated. Particular attention was paid to various phenomena occurring during charging/discharging including solid solution intercalation, phase transition, and two phase coexistence region. Finally, the heat generation rates associated with (i) Joule heating cause be polarization, (ii) heat of mixing due to ion concentration gradient, and (iii) reversible entropy changes observed at different C-rates were identified and discussed.
Enhancement of Stability of Bi2O3-Based Ionic Conductor Via Microstructural Tuning
Authors: Jeong Incheol , Jeong Seung Jin , Yun Byung-Hyun , Lee Jong-Won , Lee Chan-Woo , Jung WooChul , Lee Kang Taek
Published: July 2022

Oxygen-ion conductors with superior performance have been sought in the fields of energy conversion and storage.[1] Bi2O3-based ionic conductors which exhibit the highest known oxygen-ion conductivity have got attention for the next-generation solid electrolytes.[2] However, at intermediate temperatures below ~ 600 °C, their conductivity degrades rapidly owing to the cubic-to-rhombohedral phase transformation. Here, we demonstrate that grain boundary engineering can preserve the superior ionic conductivity of stabilized Bi2O3. To investigate the microstructural effect on stability, epitaxial and nano-polycrystalline model films of Er0.25Bi0.75O1.5 were fabricated by pulsed laser deposition. Interestingly, the grain boundary-free epitaxial film significantly improved the stability of the cubic phase while severe degradation is observed in conductivity of its polycrystalline counterpart. First-principles calculations revealed that thermodynamic stability of the cubic phase with respect to the rhombohedral counterpart is reduced near grain boundaries. These findings suggest novel aspects into the development of highly durable superionic conductors via physical manipulation of microstructure.

References

[1] E. D. Wachsman, K. T. Lee, Science 2011, 334, 935.

[2] B.-H. Yun, K. J. Kim, D. W. Joh, M. S. Chae, J. J. Lee, D.-w. Kim, S. Kang, D. Choi, S.-T. Hong, K. T. Lee, Journal of Materials Chemistry A 2019, 7, 20558.
(Keynote) Understanding How Porous Transport Layer Properties and Electrode Structure Affect the OER Electrode in an Anion Exchange Membrane Electrolyzer
Authors: Ul Hassan Noor , Duanghathaipornsuk Surachet , Chen Mengjie , Kohl Paul , Mustain William Earl
Published: July 2022

Water electrolysis to produce hydrogen is gaining significant attention due to a significant decrease in the cost of renewable energy sources such as solar, wind, and tidal etc. Among the existing water electrolysis technologies, anion exchange membrane water electrolysis has recently emerged due to its potential advantages over proton exchange membrane electrolysis and traditional alkaline electrolysis. Anion exchange membrane electrolyzers (AEMELs) can allow for the use of PGM-free electrocatalysts and low-cost component materials due to its less corrosive alkaline environment while also enabling electrochemical H2 compression.

In an operating AEMEL, the anode electrode – where the oxygen evolution reaction (OER) occurs – controls a majority of the cell’s behavior. Recent work has shown that the most statistically relevant variables controlling the cell behavior are the catalyst choice, electrode structure and the properties of the porous transport layer (PTL). While the catalyst has been widely studied in the literature, significantly less attention has been paid to the catalyst layer design and the role of the PTL in dictating performance. The PTL is one of the most important components in AEM electrolyzer as it facilitates (i) water transport from the pores of the PTL through catalyst layer to the membrane towards hydrogen evolution reaction (HER) electrode, (ii) electron transport from the grains of the PTL through the catalyst material to the reaction sites in the catalyst layer, (iii) hydroxide transport from membrane to the reaction sites in the catalyst layer, and (iv) oxygen bubble removal from the reaction sites in the catalyst layer to the pores of the PTL.

In this study, various PTLs with different properties (e.g. material, fabrication methods, features size and thickness) were used to support the catalyst layer in operating AEMELs. It was found that higher porosity facilitates multiphase (O2, H2O, OH-) transport, however, catalyst layer adhesion deceases, resulting in higher contact resistance increasing cell overpotentials. It was also found that nickel based PTLs perform relatively better than stainless steel. Moreover, fiber felts offer slightly lower overpotentials compared to sintered structures likely offering enhanced surface area for catalyst deposition and access to the active sites. Furthermore, an increase in thickness did not affect transient voltage response, though it had a negative effect on durability – likely due to low permeability, O2 blocking the pathways while increasing overall cell resistance. The experimental findings presented here would provide important insights for development of PTL materials and structures for efficient and low-cost water electrolysis.
Integrated Thermo-Electric Measurement of Electrospun Nanofiber for Polymer Electrolyte Fuel Cell
Authors: Wang Shangshang , Huang Jun , Zhang Xing , Zhang Jianbo
Published: July 2022

Polymer electrolyte fuel cell (PEFC), as an efficient hydrogen energy conversion device, has been developed for decades. Catalyst layer (CL), where the oxygen reduction reaction occurs, predominantly determines the performance of PEFC. Since 1889, the mass activity of catalyst layer has been improved for more than three orders of magnitudes, thanks to the invention of PFSA ionomer and highly dispersed catalyst on nano-sized carbon support. In recent years, introducing order into CL is bringing the CL performance to a higher level. The CLs with state-of-the-art performance feature nanofiber structures. One type of is ionomer nanofibers deposited with Pt/C catalyst on the surface, and another type is composite nanofiber containing ionomer, Pt/C catalyst, and binding polymer. Their superior performance may come from the ordered mass transport network and the size effect of nanofiber conductivity. To further improve the CL performance, the structure-property-performance relationship of ionomer nanofibers or composite nanofibers needs to be clarified.

In this work, we designed a setup to measure the proton, electron and thermal conductivity as well as the performance of a single ionomer or composite nanofiber. We developed a self-bonding method to fix the nanofiber on the micro-electrode. For proton and electron conductivity measurement, four-probe method was adopted to eliminate the electrical contact resistance and interfacial effect. For thermal conductivity measurement, Raman assisted steady state method was used to directly measure the temperature profile along the nanofiber. So, the measurement error resulting from the thermal contact resistance between the sample and the temperature sensor/heat sink can be eliminated. For performance measurement, three-electrode system was adopted using the Ag/AgCl electrode as the reference electrode and the Zn/ZnCl2 electrode as the counter electrode. We prepared nanofibers with different size, polymer content, and cross-sectional component distribution by controlling the ink recipe and electrospinning parameters. The integrated thermo-electric measurement found that the proton and thermal conductivity of nanofiber are one order of magnitude higher than bulk properties and increases with decreasing fiber radius. This is attributed to the oriented ionic morphology along the nanofiber. Furthermore, a nanofiber model was developed to extract the catalytic activity and gas diffusion coefficient of nanofiber. These characterization and modelling work can provide guidance to the design and optimization of catalyst layer with electrospun ionomer or composite nanofibers.
Reduction of Interfacial Gaps and Enhancement of PEM Fuel Cell Performance Via a New CCL|MPL Architecture
Authors: Bonakdarpour Arman , Daniel Lius , Wilkinson David P.
Published: July 2022

A new enhanced architecture for fuel cell membrane electrode assemblies (MEAs) which incorporates deposition of an MPL layer directly on a catalyst coated membrane (CCM) is demonstrated. This modified MPL helps to reduce interfacial gaps present between the catalyst layer and the conventional MPL-coated gas diffusion layer of the MEAs and reduces water accumulation, which ultimately results in higher power densities (Figure 1). Three types of commercial carbon black with different porosity and hydrophilicity were directly deposited on the low loading cathode catalyst layers (0.1 mgPt cm−2) of membrane electrode assemblies (MEAs) used in H2/O2 fuel cells. Among the carbon materials investigated, Acetylene Black- and Vulcan XC72R-based modified MPLs (mass loadings ~ 0 – 1.0 mg cm−2) lead to higher performance in the high current density regions due to their lower porosity and higher hydrophobicity. Detailed information about this approach, preparation and performance characteristics will be discussed during the meeting.

Figure 1
Transient Modeling and Optimization of a PEM Electrolyzer for Solar Photovoltaic Power Smoothing
Authors: Vudata Sai , Wang Yifan , Fenton James M. , Brooker Paul
Published: July 2022

While renewable energy fuel has always had no cost, in the past the cost of the energy conversion technology was prohibitive. Today, due to improved efficiency in the technology and substantial increases in manufacturing volume the cost to generate electricity from the renewables and the cost to store this electricity in lithium-ion batteries for four hours has made these technologies more than competitive with traditional sources. As higher renewable energy penetrations occur the variability and intermittent nature of solar photovoltaic (PV) electricity can cause steep ramping of conventional power plants, so longer term energy storage (days, weeks, instead of hours) will be needed to increase the reliability of grid operation. In Florida cloud cover of a PV field can cause rapid fluctuations of PV output requiring a fast response to smooth out the PV electric power output. A polymer electrolyte membrane (PEM) electrolyzer can serve as a utility controllable load that can be available at all times and the produced hydrogen can be sold or converted back into electricity directly through a PEM fuel cell. To study the integration of renewable solar with hydrogen for increasing grid reliability, a multi-software power control method and a transient thermal electrochemical PEM electrolyzer model has been developed.

One-dimensional ("through-plane") and two-dimensional ("through-plane" and "in-plane") un-steady state models using gPROMS 2.1.1. were developed. The model considers mass, energy, momentum and current balance equations. The thermal energy balance considers the heat transfer through the backing layer, the flowfield plates and the gas and liquid flows. Kinetic parameters used in the model were determined using parameter estimation of single cell steady state polarization curves [1]. The single cell unsteady state models were extended to a stack model by adding cells in series and parallel. Real-time PV data taken from a 8.9 MWAC solar farm from Orlando Utilities Commission’s Stanton Energy Center was scaled up to 75 MWAC to design the electrolyzer that would be sized with the typical utility PV installation in Florida. The 75 MW PV data was smoothed using a power control strategy developed in MATLAB. The developed multi-software power control method and the electrochemical dynamic stack model shows the effectiveness of an electrolyzer in smoothing the PV signal to increase the grid stability and flexibility. Results are presented of different size electrolyzers to minimize short term cloud cover spikes in power while maximizing hydrogen production and the effectiveness of the electrolyzer.

[1] Vincenzo Liso, Giorgio Savoia, Samuel Simon Araya, Giovanni Cinti and Søren Knudsen Kær, “Modelling and Experimental Analysis of a Polymer Electrolyte Membrane Water Electrolysis Cell at Different Operating Temperatures”, Energies, 11 (2018) 3272. doi:10.3390/en11123273
Experimental and Numerical Studies of the Effect of Microstructure of Ionic Conductors on Generation of Hydrogen in Solid Oxide Electrochemical Cells (SOC)
Authors: Kupecki Jakub , Niemczyk Anna , Jagielski Stanisław , Zurawska Agnieszka , Kluczowski Ryszard , Kosiorek Magdalena
Published: July 2022

Ceramic ionic conductors are applied in innovative systems for highly efficient and clean power generation. The oxygen separation membranes and solid oxide fuel cells (SOFC) and solid oxide electrolyzers (SOE) can be the examples.

Influence of various structural properties of ceramic ionic conductors which are used for solid oxide fuel cells was well-defined and described using several mathematical models. Such parameters as ionic and electronic conductivity, porosity, tortuosity, shape and distribution of pores were included. In case of solid oxide electrolysis cells, effects of these parameters on the electrolysis reaction remain unclear and obscure. There is no clearly defined correlation, neither there is an optimization tool for modification of the parameters to maximize the performance of solid oxide cell operating in regenerative mode. For that reason it is necessary to perform a complete comprehensive analysis combining both the experimental and numerical techniques to identify the key microstructural parameters and their correlation with the performance of electrochemical reaction. The work was aimed at verification of data presented in earlier studies which advised that porosity of electrodes of SOEs needs to be different than in the case of SOFCs, however different values were claimed. Mingyi et al. [1] indicated that optimum porosity for SOEC is about 45%, however several other studies advised on different values.

This paper presents results of numerical simulations and correlation of material properties with operational characteristic of a solid oxide electrochemical cell which were followed by initial experimental investigations towards validation of the numerical model, including the analysis of selected operational states. Model was established on the basis of theoretical correlations between microstructural parameters and macro-level performance. It was used for performing variant analysis of different modes of operation under varied conditions. The outcomes of the numerical investigations made it possible to define the requirements for fabrication of modified cells for high temperature electrolysis which were studied.

The work presents preliminary results of electrochemical characterization of modified cells and an attempt to generalize the model of SOC customized to highly efficient electrolysis.

The general concept of optimizing the performance of SOE by fine-tuning of the microstructure which was proposed earlier [2] is assessed throughout experiments using in-house 50 mm x 50 mm cells fabricated in the Institute of Power Engineering. The proposed path for tailoring the microstructural properties is presented and discussed.

References

[1] L. Mingyi, Y. Bo, X. Jingming, Ch. Jing, Int J Hydrogen Energy. 2010,35,2670-2674.

[2] J. Kupecki, J. Milewski, ECS Trans. 2018,83(1),171-178.

Figure 1
(Invited) Understanding Oxygen Distribution in the Porous Transport Layer of Proton Exchange Membrane Water Electrolyzer (PEMWE) Using x-Ray Computed Tomogrpahy
Authors: Kulkarni Devashish , Zenyuk Iryna V.
Published: July 2022

To reach Department of Energy (DOE) target of 1$ cost for 1 kg of H2 production in 1 decade the cost of green hydrogen generation needs to decrease. IrOx is a used as an electrocatalyst in anode electrode of proton exchange membrane water electrolyzers (PEMWE) and its loading must decrease below 2 mg/cm2 to reach the cost targets for electrolysis. One of the hurdles of catalyst layers with low IrOx loading is the inplane electric conductivity, which will be low as IrOx is not supported by carbon or other conductive additive. Therefore, the design of porous transport layers (PTLs) becomes critical to ensure a good interface contact area with the catalyst but at the same time optimal oxygen removal from the catalyst. In our earlier study we showed that PTLs with intermediate porosities of ~60 % achieved this goal [1]. In this work we use operando x-ray computed tomography to visualize oxygen transport inside the PTLs for the cells having various catalyst loadings and various PTLs (sintered and fiber). Using a staining agent of NaI we were able to differentiate between water and oxygen as shown by Figure 1. Oxygen transport pathways and oxygen content within the PTLs was studied using various cell configurations and current densities. This work will identify a path forward for designing PTLs for PEMWE.

References:

Peng, X., Satjaritanun, P., Taie, Z., Wiles, L., Keane, A., Capuano, C., Zenyuk, I. V., Danilovic, N., Sci.2021, 8, 2102950.

Figure 1
(Invited, Digital Presentation) Mechanistic Insight into the Electrocatalytic Reduction of Nitrate to Ammonia
Authors: Chen Yu , Senftle Thomas Patrick
Published: July 2022

The excessive use of nitrogenous fertilizers has thrown the nitrogen cycle out of balance. As a result, nitrate contamination in our water resources is pervasive, creating severe environmental and health consequences. The electrocatalytic reduction of nitrate to ammonia is an attractive strategy for addressing this issue, as it would treat nitrate contamination while simultaneously recovering the active nitrogen component. Several examples in the literature demonstrate the electrocatalytic reduction of nitrate, yet the water treatment industry has not adopted catalysis as a general strategy for nitrate removal and resource recovery. Catalyst selectivity has been a key roadblock to the adoption of electrocatalytic nitrate reduction technology, as the nitrate reduction mechanism is complex and highly sensitive to catalyst composition, structure, and operating environment. In this work, we apply density functional theory (DFT) to understand key factors that influence the nitrate reduction mechanism. We find that elementary reactions on the catalyst surface are highly sensitive to surface coverage. For example, metals that exhibit high coverage of adsorbed NO* promote N-N coupling and the production of dinitrogen over ammonia. Our results also show that nitrate adsorption and dissociation is sensitive to the structure of the exposed catalyst facet, and thus the morphology of the catalyst particle heavily influences reaction selectivity. In particular, we find that the triangular arrangement of atoms on (111) facets yield a lower nitrate dissociation barrier compared to the square arrangement of atoms on (100) facets. This behavior explains trends observed by our experimentalist collaborators, who found enhanced nitrate activation rates on octahedron particles that predominantly expose the (111) facet. These two examples illustrate how mechanistic insight from DFT can be used to guide strategies for tailoring catalyst composition and structure to achieve active and selective nitrate reduction to ammonia.
Implementing Catalysts into Electrospun Composite Carbon Nanofiber (CNF) Electrodes for Ammonia Production from Photoelectrocatalytic Nitrate Reduction
Authors: Hesterberg Butzlaff Ashley , Alsaedi Sattar , Fields Jacob , Cwiertny David , Jawahar Hussaini Syed Mubeen
Published: July 2022

While novel carbon nanomaterials can serve as electrodes with exceptional electrical properties, carbon nanofibers (CNFs) merit further investigation for applications as electrodes in environmentally-relevant photoelectrocatalysis. Tunable, durable CNF structures can be easily synthesized as a convenient framework for catalyst implementation. Herein we investigate how catalysts can be integrated into carbon nanofiber mats to enhance the photoelectrocatalysis of nitrate reduction. As a frequent contaminant in agriculturally-intensive regions, the negative value of nitrate containing streams may be used to produce ammonia as a value-added product and to improve water quality in the resulting output stream. Catalysts were implemented using different methods (in situ sol gel, chemical reduction, electrochemical) on two different CNF composites (with and without titanium dioxide). We focus on copper as a catalyst due to its promising performance and economic advantage over traditional platinum group metals. After thorough characterization of the catalyst-CNF frameworks via XPS, XRD, Raman, the catalyst performance was measured by nitrate reduction product selectivity, catalyst lifetime, and Faradaic efficiency. The flexibility of CNF synthesis and catalyst implementation will provide photoelectrodes with properties desirable for the electrochemical reduction of nitrate in environmental conditions to generate valuable products. This work will help identify the types and properties of next-generation carbon composite electrode materials that are most promising for resource recovery and for improving photoelectrochemical catalytic cells purposed for drinking water treatment.
(Invited) Electrified Resource Recovery Via Nutrient Reduction from Wastewater
Authors: Daramola Damilola , Trembly Jason
Published: July 2022

Significant anthropogenic activity has been crucial in maintaining global population growth by fixing macronutrients required for crop growth into the soil. Two of these macronutrients – nitrogen (N) and phosphorus (P) – are also responsible for detrimental environmental impact via eutrophication. This eutrophication is driven by excess application of inorganic fertilizer products and organic animal waste from animal feeding operations; components that eventually end up in natural bodies of water due to erosion and leaching. Furthermore, in digester-equipped municipal wastewater treatment facilities, elevated N and P levels in the liquid stream recycled to the head of the facility drives increased resource consumption for nutrient reduction: chemicals for P management and energy for N management. Therefore, opportunities exist to simultaneously minimize environmental impact and energy consumption through improved nutrient management techniques, thus addressing issues at the Food-Energy-Water nexus.

Various electrochemical techniques are in early-stage development for an electrified approach to recovering these nutrients and reducing their environmental impact including bio-electrochemical1, electro-deionization2 and electrocoagulation3 approaches. This talk will focus on the indirect electrochemical approach: oxygen/water reduction to promote favorable pH conditions at the electrode surface for nutrient precipitation. Preliminary work4,5 has shown the viability and utility of this approach for nitrogen and phosphorus reduction in synthetic wastewater simulating animal waste. Additional findings describing the impact of competing ions, mass transport and electrolyte thermodynamics on nutrient reduction and recovery will be presented at the conference. An outlook on how this approach impacts energy consumption within the context of decarbonization of the manufacturing sector will also be discussed.

References

Y. Lei et al., ACS Sustain. Chem. Eng., 7, 8860–8867 (2019).

Y. Bian, X. Chen, L. Lu, P. Liang, and Z. J. Ren, ACS Sustain. Chem. Eng., 7, 7844–7850 (2019).

L. Kékedy-Nagy et al., J. Am. Chem. Soc., 142, 18844–18858 (2020).

Z. Belarbi and J. P. Trembly, J. Electrochem. Soc., 165, E685–E693 (2018).

Z. Belarbi, D. A. Daramola, and J. P. Trembly, J. Electrochem. Soc., 167, 155524 (2020).
Methanol Electro-Oxidation over Combustion Synthesized Silver Based Electrocatalysts
Authors: Logade Khulood , Shafath Sadiyah , Kumar Anand , Abu Reesh Ibrahim
Published: July 2022

Herein, we report the electrocatalytic properties of Ag-M/C (M=Cu, Zn, Fe, Cr, Mn) catalysts produced using solution combustion synthesis (SCS) method for methanol oxidation reaction (MOR). The morphological properties of the synthesized catalysts were studied using SEM, EDX, TEM, XRD and XPS techniques. The characterization results indicated that out of all catalysts, AgCu/C had the most porous surface, small and well distributed particles with high surface area making it a good choice for electrocatalytic experiments. The XPS results showed a shift in peak in the AgCu/C sample due to the charge transfer between Ag and Cu indicating a strong interaction between Ag and Cu. The electrochemical properties of the catalysts were studied at 1 M methanol concentration and 1 M KOH (electrolyte) concentration by performing Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV) experiments. It was observed that AgCu/C exhibited a greater electrocatalytic activity and was therefore, found to be a more viable catalyst for MOR. Following this, further concentration studies were conducted on AgCu/C for methanol concentrations of 0.5M, 1M, 1.5M, 2.5M to evaluate the rate dependency of the catalyst on MeOH concentration. The CV and LSV curves depicted a linear increase in current density proportional to the increase in methanol concentration, indicating power-law dependency. The catalyst also displayed long-term stability when chronoamperometry test was performed for 20 hours.
Evaluating Bipolar Membrane Electrolyzers for Green Hydrogen Production from Impure Water Sources
Authors: Marin Daniela , Perryman Joseph T. , Nielander Adam , Jaramillo Thomas F , Hubert McKenzie , Boettcher Shannon W.
Published: July 2022

Non-potable water represents a vast resource that can enable hydrogen generation to support energy storage and chemical manufacturing, as well as oxygen generation for undersea applications. Ionic impurities present in brackish water, wastewater, and seawater are highly detrimental to the operational stability of state-of-the-art proton-exchange membrane water electrolyzers (PEMWE). Chloride (Cl-) impurities are particularly pernicious, as Cl- can be oxidized to form reactive Cl2/HOCl/OCl- species at the anode which accelerates the degradation of electrolyzer components. In contrast, bipolar membrane water electrolyzer (BPMWE) architectures can be used to control the transport and reactivity of feed impurities by leveraging ion-selective membranes that allow for independent control of electrolyte pH at each electrode, thereby opening a path toward impurity-tolerant electrolyzers. In this work, we compare the performance of BPMWE and PEMWE architectures fed by simulated seawater (0.5M NaClaq) at current densities up to 500mA cm-2 for up to six hours. We present quantification of the transport of ions across the BPM, as well as oxidized chlorine species generation. In the PEMWE construct, we observe up to 14 μM of oxidized species after only 6 hours of operation; in the BPMWE, chloride oxidation is successfully suppressed (<0.1μM) at current densities below 500mA cm-2. Furthermore, we observed that Cl- ion crossover was constant even as current density increased, highlighting that cross-membrane H+/OH- transport is favored at high current densities.
Cell Culture Monitoring using Coplanar Electrochemical Transistors
Authors: Williams Kia , Fanjul Pablo
Published: July 2022

In vitro cell death process monitoring is a method widely used in medical and pharmacological studies to know the effect of drugs and toxins on tissue models. This work presents a study of cell viability using commercial platforms designed for the generation of electrochemical transistors as sensor devices for different cultures of HEK294 embryonic kidney cells. In this work, we cover the idea of using an electrochemical transducer-based device to measure the number of cells deposited or growing on the source-drain channel. Using this method, it has been observed that the deposited cells behave like the semi-conductor material. Therefore, drain-source intensity versus gate-source voltage varies depending on the number of cells that are covering the drain-source system, with the measured intensity increasing with the growing number of cells.

The electrochemical signals of different cultures have been compared to the number of cells measured by microscopy and a correlation has been performed. Different cell cultures have been evaluated before and after, and considerable decreases in current intensity have been observed, indicating that damage has taken place.

Therefore, these transistors have proven to be an alternative for the study of cell viability, maintaining the integrity of the sample and being able to increase the number of studies performed on it. In addition, the monitoring of the evolution of cellular activity can be performed simpler and faster, providing comparable results with the advantage of maintaining a usable sample.

This work was supported by the Project "NANOBIO-TEER" (IDE/2018/000485 and IDE/2018/000415), co-financed through IDEPA and ERDF fund.
(Digital Presentation) Facile Synthesis of Pillar[6]Quinone and Investigation of Its Electrochemical Properties
Authors: Hirohata Tomoki , Shida Naoki , Ogoshi Tomoki , Tomita Ikuyoshi , Inagi Shinsuke
Published: July 2022

Pillar[n]arene (n: number of units), macrocyclic para-arylene methylene molecules, have attracted attention owing to their symmetrical structures, host-guest properties, and original supramolecular assembly characteristics.1 Similarly, their quinone counterparts, pillar[n]quinone (P[Q]n), are also fascinating macrocycles containing electron-deficient quinone units, and therefore have potential application for novel host-guest chemistry and redox active materials. A hexagonal molecule, pillar[6]quinone (P[Q]6), is expected to form densely packed structures and a candidate for organic active material but the synthesis of P[Q]6 still remains a challenge.

We previously demonstrated that the electrochemical oxidation (1.0 V vs. SCE) of 1,4-dihydroxypillar[6]arene (P[HQ]6) in methanol afforded micrometer scale hexagonal cylindrical depositions on electrode surfaces, which were composed of partially oxidized P[HQ]6-m[Q]m (composed of both hydroquinone and benzoquinone units) aggregating via quinhydrone formation.2

In this work, we successfully synthesized P[Q]6 for the first time by oxidation of its hydroquinone precursor P[HQ]6. Electrochemical oxidation (1.2 V vs. SCE) of P[HQ]6 in methanol gave the similar hexagonal cylindrical crystal of P[Q]6 evidenced by single crystal X-ray diffraction, NMR and HRMS analyses. In the crystallographic data, all quinone moieties seem to have intermolecular CH-O interaction between adjacent macrocycles, resulting in the formation of a hexagonal packing structure. In addition, we also found that scalable synthesis of P[Q]6 was possible by chemical oxidation of P[HQ]6 with phenyliodine(III)bis(trifluoroacetate) in 1,1,1,3,3,3-hexafluoro-2-propanol.

To understand the electrochemical properties and electron-transfer behavior of P[Q]6, various voltametric studies were carried out. We revealed that three electrons are injected first, followed by stepwise three one-electron reductions due to the electrostatic repulsion in the latter electron-transfer process.

Reference

T. Ogoshi, T. Yamagishi, Y. Nakamoto, Chem. Rev.,
116, 7937 (2016).

C. Tsuneishi, Y. Koizumi, R. Sueto, H. Nishiyama, K. Yasuhara, T. Yamagishi, T. Ogoshi, Tomita and S. Inagi, Chem. Commun., 53, 7454 (2017).

T. Hirohata, N. Shida, H. Uekusa, N. Yasuda, H. Nishihara, T. Ogoshi, I. Tomita, S. Inagi, Chem. Commun., 57, 6360 (2021).

Figure 1
(Digital Presentation) Bipolar Electrolytic Micelle Disruption Method: Fabrication of Gradient and Patterned Organic Thin Films
Authors: Inagi Shinsuke , Zhou Yaqian , Shida Naoki , Tomita Ikuyoshi
Published: July 2022

The method for the preparation of organic thin films (TFs) is significant due to its attractive potential applications in various devices such as photovoltaic cells, transistors and sensors. However, the conventional preparation methods are expensive and time-consuming. Besides, it is difficult to control the shape and the thickness of the film. In this study, a facile and general bipolar electrolytic micelle disruption (BEMD) approach was firstly established to fabricate a variety of gradient and circular TFs,1 benefiting from the in situ generated controllable potential distribution on a bipolar electrode (BPE).2

The micellar electrolytic solution was prepared by the addition of organic compound to an aqueous micellar solution containing electroactive surfactant of (11-ferrocenylundecyl)trimethylammonium bromide (FTMA) or α-(11-ferrocenylundecyl)-ω-hydroxypoly(oxyethylene) (FPEG), and lithium sulfate (Li2SO4).3 The prepared electrolyte was used for bipolar electrolysis under different conditions.

A polymerizable monomer of N-vinylcarbazole (NVC) was solubilized in micelles composed of a cationic surfactant of FTMA, while copper phthalocyanine (CuPc) and aggregation-induced emission (AIE) compounds were dispersed in micelles constructed from a nonionic surfactant of FPEG. Here, a U-shaped bipolar electrolytic setup generated a sigmoidal potential distribution on the BPE, while a cylindrical bipolar electrolytic setup provided a site-selective potential feature on the BPE. When the micelles composed of electroactive surfactants moved to the BPE surface, the structure of micelles was disrupted selectively on the BPE surface with the oxidation of surfactants. In this process, various organic compounds incorporated into micelles were released on the localized area of the BPE, following the potential distribution. Finally, a variety of gradient and patterned organic thin films formed on the BPE surface. The gradient feature was characterized by UV–Vis analysis, thickness measurement and surface morphology analysis. Besides, modulation of the voltage applied to the driving electrodes or electrolytic solution allowed control of the film thickness.

References:

Y. Zhou, N. Shida, I. Tomita, S. Inagi, Angew. Chem. Int. Ed., 60, 14620 (2021).

N. Shida, Y. Zhou, S. Inagi, Acc. Chem. Res.,
52, 2598 (2019).

T. Saji, K. Hoshino, Y. Ishii, M. Goto, J. Am. Chem. Soc., 113, 450 (1991).

Figure 1