bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Energy Technology Division Research Award) New Materials vs. Reaction Engineering in Anion Exchange Membrane Fuel Cells
Authors: Mustain William Earl 
Published: August 2024

In recent years, the desire to design, create and/or discover advanced functional nanomaterials has changed the way that faculty members and graduate students approach engineering research. Though materials can (and likely will) make a significant impact on most technologies, the truth is that in most disciplines, materials with highly complex structures remain on the fringes of realistic deployment. In some cases, even when so-called “advanced” materials are discovered there are significant difficulties in transitioning them from ex-situ tests to the real reacting environment. Therefore, we must be careful to understand that material chemistry and structure are only two variables in an extremely complex system and often times there are other fundamental (e.g. electronic mobility, thermodynamic barriers, diffusivity) and engineering (porosity, concentration, temperature) properties that drive behavior in such environments. Additionally, there are systems where materials are being sought without a clear understanding of what is truly limiting performance and durability or the properties that are required of a real engineered system to operate effectively.
Anion exchange membrane fuel cells (AEMFCs) are an example system where the literature is littered with exotic materials that claim to improve activity and stability (presumed as performance and durability in real devices). However, it will be shown that for several years, such new materials had limited success (if any) in advancing performance and durability. This talk will summarize ~five years of work in AEMFCs where the performance and durability of AEMFCs were improved significantly without any new materials – just using traditional chemical engineering principles for reactor engineering. Only later – once device operation was well understood and controlled – were new materials helpful. On the operational side, the main discussion point will be the transport of water. On the materials side, new membranes and catalysts will be discussed. The talk will end with perspectives on transitioning AEMFCs to more realistic operating environments, including the mitigation of effects from CO2.
Electrospun Nanofiber Catalyst Support for Polymer Electrolyte Membrane Fuel Cells
Authors: Pedram Sara , Wang Yinyu , Jankovic Jasna 
Published: August 2024

Increased energy demand and environmental concerns are driving the search for cleaner, more efficient power generation. Fuel cells (FCs) offer a solution by converting chemical energy from fuel and oxidant directly into electricity with high efficiency (40-70%) and zero carbon emissions. Enhancing the performance and durability of polymer electrolyte membrane fuel cells (PEMFC) while reducing costs remains a significant challenge. The current planar FC design presents various issues, including high costs and weight due to metal or graphite bipolar plates, high-pressure drop-in reactant gas diffusion channels, reactant gas transport losses in the agglomerate-type catalyst layers, water flooding, to name just a few. Exploring novel biomimetic designs may offer solutions to these challenges.
This research is inspired by vascular plant structures to improve mass transport and efficiency. The cathode uses carbon nanofibers (CNF) made via electrospinning, with Pt nanorod catalyst on the surface in an open electrode layout. This CNF-type cathode was used to create a membrane electrode assembly (MEA), using a commercial membrane and typical anode. A number of parameters were varied, including overall Pt loading, Pt concentration on the fibers, design with and without gas diffusion layer, using CNF mat. The MEAs were tested to establish links between structure, properties, and performance. Performance was evaluated through polarization curves and electrochemical impedance spectroscopy, while beginning of test and end of test structure was investigated using microscopy. CNF-based MEAs achieved a higher current density compared to the commercial MEA at lower Pt loading. This suggests that reduced loading still maintained acceptable Pt utilization, reducing the Pt amount in the MEA. In summary, the CNF catalyst support displayed improved durability, mass transport, Pt utilization, and efficiency thanks to its porous mesh structure.
Sustainable Production of Hydrogen through High-Temperature Molten Salt Electrolysis
Authors: Kamali Ali Reza 
Published: August 2024

The green and cost-effective production of strategic materials, including steel on a large scale is pivotal for fostering sustainable industrial development. Hydrogen emerges as a key component for clean steel production, but its sustainable and economical generation remains a barrier to widespread utilization in iron and steelmaking, as well as other applications. Conventional water electrolysis, a common method for carbon-free hydrogen production, faces economic challenges, equipment corrosion, and the use of expensive catalysts with high over-potentials, limiting its viability. Additionally, the transportation of hydrogen from the electrolyzer to utilization units poses cost and safety concerns. Addressing these challenges, this presentation discusses the electro-generation of hydrogen in high-temperature molten salts. The generated hydrogen can then be utilized in situ for the production of metals, alloys, and other commercially valuable materials. Leveraging high temperatures improves the thermodynamic potential and efficiency of the water-splitting process. Remarkably, electrolytic hydrogen produced in molten salts, operating at a potential of around 1 V, has the capacity to facilitate the production of a diverse range of materials such as Fe, Mo, W, Ni, and Co-based alloys.

References

K. Xie, A.R. Kamali*, Energy Convers. Manag. 251 (2022) 114980
D. Qiao, K. Xie, A.R. Kamali*, Mater. Adv. 1 (2020) 2225
K. Xie, A.R. Kamali*, Int. J. Hydrogen Energy 44 (2019) 2 4353
A.R. Kamali*, RSC Advances 10 (2020) 36020
A.R. Kamali, US2021009415 (2023)
K. Xie, A.R. Kamali*, Green Chem.21 (2019)198
In-Situ structural and Adsorbate Induced Surface Evolutions Monitored By Electrochemical Stress Measurements
Authors: Tavassol Hadi 
Published: August 2024

We report on in-situ electrochemical stress measurements of well-defined surfaces during electrochemical reactions in aqueous media. Electrochemical stress measurements during hydrogen evolution reaction (HER) on Pt surfaces shows distinct pH-dependent features which we assign to anion adsorption/desorption and hydrogen adsorption/desorption. Our surface stress analysis shows higher hydrogen induced stresses at alkaline environments than stresses observed at acidic pHs. This observation is consistent with the monotonic change in apparent hydrogen binding energy with pH, most likely due to the changes in water interactions with surface. However, H-induced surface stress shows a dramatic increase around neutral pH. We will present our analysis of how interfacial water may explain this effect. Additionally, we will show how in-situ underpotential deposition of Cu on Pt and Ni on Au changes Had induced effects on these surfaces.
We will also discuss the structural and compositional evolution of Sr2Fe2O6-δ thin films during oxygen evolution reaction (OER). Interestingly, in-situ electrochemical stress measurements show a tensile stress response during OER which is different from Au model surfaces. We will present our analysis of how potential controlled formation of iron (oxy)hydorxides may explain in-situ stress response and structural evolution of perovskite type structures during OER.
In summary, our analysis shows how adsorbate-induced effects can be used to explain surface reactions, and particularly explain and provide insight into interfacial structural changes and water interactions at different pHs.
(Invited) Electrochemical Processes Drive Membrane-Based Recovery of N and P
Authors: Jassby David , Iddya Arpita 
Published: August 2024

We expend a large amount of energy and money on the treatment of municipal and industrial wastewater, relying on redox reactions to transform contaminants (e.g, ammonium, reduced carbon) into other less/non-harmful species (N2/NO3
-, CO2), or on biological accumulation approaches that sequester contaminants into bacteria (e.g., biomass, PO4
-3). In the worst case, these contaminants are simply released into the environment where they cause harm and are lost. Yet, many of these contaminants are actually valuable resources (e.g., NH3, PO4
-3). In an age where environmental sustainability and climate change mitigation are of utmost importance, it makes little sense to invest large amounts of energy into the conversion and elimination of these valuable resources, only to turn around and use fossil fuels to produce more. In addition, the value of these resources is often higher than the value of the treated water, making their recovery an economically-attractive prospect.
Here, we discuss our recent work on membrane-based separations of ammonia, phosphate, and volatile fatty acids (VFAs) from different waste streams. Critically, in all cases we achieve separation by leveraging electrochemical reactions and processes. For ammonia recovery, we utilize an electroactive membrane contactor that is used as a cathode – the application of cathodic potentials to the membrane surface increases the local pH at the membrane/water interface, which transforms ammonium to ammonia and enables its effective volatilization and recovery across the membrane. For VFA recovery, we use a composite electroactive membrane that combines electrothermal heating and an electrochemical pH swing to protonate and extract these volatile species from water. Finally, for phosphate separation, we engineer a phosphate-specific pathway through a cation exchange membrane, and use electrodialysis to pull phosphate ions from a mixed anion solution. Together, these approaches can be used to recover valuable products from complex waste streams, such as municipal and industrial wastewater, without the need to rely on bulk pH and temperature modification.
(Invited) Green Ammonia Production from Electrochemically Upcycling Waste Nitrogen in an Membrane-Free Alkaline Electrolyzer
Authors: Li Wenzhen , Chen Yifu , Liu Hengzhou , Gu Shuang 
Published: August 2024

NH3 is an essential nutrient for life, but its production through anthropogenic N2-fixing process has caused alarming damages to ecosystems and human health. Excessive NO3
- leakage into water bodies due to overfertilization has led to the formation of "dead zones" in coastal areas. Denitrification generates N2O, which is 300 times more potent than CO2. Restoring the balance between the generation and elimination of Nr is an urgent task for humanity. Efforts to address the negative impact of human-generated Nr have focused on converting it to harmless N2 or improving its utilization in the nitrogen cycle. One promising method is electrochemical conversion, which can eliminate Nr without additional oxidants/reductants. However, achieving selective NO3RR toward N2 is challenging. An alternative approach is to convert other forms of Nr to NH3 in an electrochemical reactor, which could reduce the environmental impact of Nr and decrease the NH3 demand from the Haber-Bosch process, while also reducing the use of fossil-derived H2.
In this work, we report our work on the development of a membrane-free alkaline electrolyzer (MFAEL), which transforms Nr into NH3 as the sole N-containing product. With the inexpensive and robust MFAEL system, we achieved an ampere-level partial current density towards NH3 production. By properly choosing the conditions of NH3 collection from MFAEL, continuous production of pure NH3-based chemicals can be realized without the need for additional separation procedures. Techno-economic analysis (TEA) suggests the potential economic feasibility of the waste-to-NH3 process by coupling electrodialysis (ED) for Nr concentration and the MFAEL process for Nr conversion, offering an all-sustainable route for upcycling waste N into the highest-demanded N-based chemical product. Our recent efforts on green-ammonia capture CO2 and reduction to valuable chemicals will also be briefly presented.
Limitations and Opportunities of Self-Supported Co-Based Anodes for Pure Water-Fed Anion Exchange Membrane Water Electrolyzers
Authors: Kwak Minkyoung , Boettcher Shannon W. 
Published: August 2024

Hydrogen has been regarded as an energy source with a potential to be used in various sectors, including transportation, power generation and industrial processes1-3. Producing hydrogen via water electrolysis using green electricity will be necessary for a sustainable future. Proton exchange membrane water electrolysis (PEMWE) is one of mature and leading electrolysis technologies, while anion exchange membrane water electrolysis (AEMWE) is regarded as a new, emerging technology4. However, PEMWE system suffers from their expensive cost and scarcity of iridium-based oxygen evolution reaction (OER) catalysts, having no alternative OER catalysts. Compared to PEMWE, AEMWE can be pursued with non-platinum group metal (non-PGM) thanks to its alkaline environment4,5.
Here, non-PGM Co-based catalyst coated anodes were prepared using a simple hydrothermal reaction followed by heat treatment. Different phases and crystallinity of cobalt-based anodes were prepared and tested in pure water-fed AEMWE devices. To investigate the catalyst-ionomer/membrane interfaces at the anodes, the loadings of Co3O4 catalyst and ionomer topcoats were controlled. The cell performance in polarization curves was correlated with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements. The comparison of anodes operated with pure water feed and with supporting electrolyte was made to highlight the importance of catalyst-ionomer interface in pure water-fed AEMWE. Lastly, our self-supported Co3O4 anode outperformed a commercial Co3O4 NP ink-based anode, projecting a potential of direct growth of catalyst materials on PTLs in pure water-fed AEMWE.
Reference
(1) Agyekum, E. B.; Nutakor, C.; Agwa, A. M.; Kamel, S. A Critical Review of Renewable Hydrogen Production Methods: Factors Affecting Their Scale-Up and Its Role in Future Energy Generation. Membranes
2022, 12 (2).
(2) Qusay, H.; Sameer, A.; Aws Zuhair, S.; Hayder, M. S.; Marek, J. Green hydrogen: A pathway to a sustainable energy future. Int. J. Hydrogen Energy
2024, 50, 310-333.
(3) Joonsik, H.; Krisha, M.; HeeJin, C. A review of hydrogen utilization in power generation and transportation sectors: Achievements and future challenges. Int. J. Hydrogen Energy
2023, 48 (74), 28629-28648.
(4) Lee, S. A.; Kim, J.; Kwon, K. C.; Park, S. H.; Jang, H. W. Anion exchange membrane water electrolysis for sustainable large-scale hydrogen production. Carbon Neutralization
2022, 1 (1), 26-48.
(5) Juchan, Y.; Myeong Je, J.; Xiaojun, Z.; Yoo Sei, P.; Jooyoung, L.; Sung Mook, C.; Yadong, Y. Non-precious electrocatalysts for oxygen evolution reaction in anion exchange membrane water electrolysis: A mini review. Electrochem. Commun.
2021, 131, 107118.
Electrocatalytic Conversion of CH4 to High Value-Added Liquid Fuel over Binary Metal Oxide Tandem Catalysts
Authors: Xu Nengneng , Wang Yudong , He Zizhou , Zhou Xiao-Dong 
Published: August 2024

As the main component (> 85%) of combustible ice and shale gas, methane (CH4), plays a significant role in the greenhouse effect.(1) Although CH4 was widely used to synthesize high value-added Cx oxygenates via indirect industrial reforming with high-energy consumption. The accurate control of oxidation degree in CH4 conversion remains a great challenge.(2) Therefore, it is difficult to achieve high conversion rate and high selectivity at the same time. The convenience and reliability of the control of reaction potential, as one of the advantages of electrocatalysis technology, can effectively address the above problems.(1, 3) Electrochemical technologies of CH4-to-Cx oxygenates are regarded as one of the most attractive pathways to produce bulk industrial liquid fuels.(4) Especially in the premise of clean energy as an energy source, the electrochemical conversion of methane demonstrates very advantageous market potential. In this work, we prepared a ZrO2 modified FeOx binary metal oxides tandem catalyst to accelerate partial oxidation of CH4 under ambient condition. With CO3
2- as an oxidant, ZrO2@FeOx tandem catalyst shows remarkable CH4 conversion performance with large current density gap (13.65 mA cm-2) and long-term electrochemical stability (negligible attenuation (8 %) after 48 hours) in three-electrodes cell. In addition, in a flow reactor, ZrO2@FeOx-based electrode also exhibits a highly stable operating lifespan over 72 hours at a large current density 50 mA cm-2 and achieve a feasible CH4-liqid fuel conversion with high total faradaic efficiency.
References

F. Liu, Y. Yan, G. Chen and D. Wang, Green Chemistry, 26, 655 (2024).

S. Yuan, Y. Li, J. Peng, Y. M. Questell-Santiago, K. Akkiraju, L. Giordano, D. J. Zheng, S. Bagi, Y. Román-Leshkov and Y. Shao-Horn, Advanced Energy Materials, 10, 2002154 (2020).

M. R. A. Kishore, S. Lee and J. S. Yoo, Adv Sci (Weinh), 10, e2301912 (2023).

L. Fu, R. Zhang, J. Yang, J. Shi, H. Y. Jiang and J. Tang, Advanced Energy Materials, 13 (2023).
Molecular Simulations Study of the Ionic Adsorption on Oscillating Carbon Electrodes
Authors: Gaudy Nicolas , Salanne Mathieu , Merlet Céline 
Published: August 2024

Molecular dynamics simulations are a method of choice to study, at microscopic scales, the adsorption of electrolyte ions onto the electrodes of capacitive storage systems such as supercapacitors1.
Here, we use all-atom molecular dynamics simulations to model a pure ionic liquid electrolyte ([EMIM][TFSI], 1-ethyl-3-methylimidazolium trifluoromethanesulfonylimide) in contact with graphite electrodes (Figure:
Supercapacitor composed of graphite electrodes (in light blue) in contact with a pure ionic liquid electrolyte ([EMIM][TFSI], atoms colored according to the atom type. The arrows illustrate the oscillations of electrodes used to probe the influence of such a motion on the interfacial liquid.)
When applying a potential difference between the two carbon electrodes, a migration of counter ions is observed, ultimately leading to a compensation of the charges carried by the electrode atoms. The adsorption dynamics depend on several parameters (electrostatic interactions, coordination number, viscosity of the electrolyte, size of the ions etc.) and influence the power of these capacitive systems2. In order to improve the performance of supercapacitors, it is then important to describe and understand interfacial properties at a molecular scale.
Experimentally, an Electrochemical Quartz Crystal Microbalance (EQCM) can be used to study ion flow on top of the electrode. The frequency variations recorded by the EQCM are linked to variations in the mass adsorbed on the quartz surface, thus making it possible to study the dynamics of ion adsorption during the charge of a supercapacitor.3

However, variations in quartz frequency can influence the stability of the electrode-electrolyte interface, thus modifying ionic interactions and adsorption dynamics at the electrode surface4.
Here, thanks to molecular simulations, we have access to the adsorption rate of ions, to their re-orientation, to the variation of charge of the electrode atoms during adsorption etc. This allows us to study in detail the mechanisms governing the electrolyte-electrode interface during the charging of supercapacitors as part of EQCM. And study the extent to which perturbations caused by quartz oscillations in the ionic liquid affect electrode-electrolyte interfacial properties.

References

1 K. Xu, H. Shao, Z. Lin, C. Merlet, G. Feng, et al.. ENERGY & ENVIRONMENTAL MATERIALS, 3, 235-246 (2020)

2C. Péan, B. Rotenberg, P. Simon, M. Salanne, ELECTROCHIM. ACTA, 206, 504-512 (2016)

3Y-C. Wu, J. Ye, G. Jiang, K. Ni, N. Shu, P-L. Taberna, Y. Zhu, P. Simon, ANGEW. CHEM. INT. ED., 60, 13317-13322 (2021)

4Nikolai V. Priezjev, MICROFLUIDICS AND NANOFLUIDICS, 14, 225-233 (2013)

Figure 1
An Electrochemical Phase Field Model Applied to Molten Salt Dealloying Corrosion of Ni-Alloys
Authors: Bieberdorf Nathan , Bognarova Xueyang , Capolungo Laurent , Asta Mark 
Published: August 2024

Metal alloys in contact with molten salts are known to corrode via a dealloying process, wherein the less-noble alloy elements (e.g. Cr) are selectively oxidized and dissolved, leaving behind a corroded structure that is enriched in the more-noble elements (e.g. Ni). In some cases, this can lead to molten salt infiltration into the alloy through discrete channels along specific microstructural features (e.g. grain boundaries). However, in other cases the dealloying process promotes a more full-scale attack of the alloy, generating a fine-scale ligament structure. This process can severely degrade the alloy’s structural integrity, which limits the practicality of these material systems in otherwise promising applications (e.g. molten salt-cooled power reactors).
The thermokinetic conditions for dealloying corrosion depend on the salt chemistry and the metal microstructure, which together inform the reaction process occurring at their interface. The salt chemistry and oxidant content set the electrochemical potential for selective oxidation of the less-noble elements. The associated oxidation rate is expected to depend on the presence of an interfacial structure (e.g. double layer) and also on the transport rates of reactants towards the interface (e.g. species diffusion in the metal and oxidizer transport in the salt) and reaction products away from the interface (cation transport in the salt). The corrosion rate and morphology will also depend strongly on the rate of transport laterally along the metal-salt interface, since the reorganization of the more-noble species (Ni) towards ligament formation facilitates the attack of the alloy by the corrosive agent. It has been hypothesized that molten salts enhance this rate of solute diffusion along the metal interface.
In this work, we propose an electrochemical phase field model to predict the microstructural evolution of model Ni-alloys undergoing dealloying corrosion in molten fluoride salts. The model incorporates metal oxidation and dissolution via experimentally determined redox potentials and activity coefficients for metal species in the molten salt. We show that the corrosion rate and development of pores is strongly dependent on solute transport rates within the metal and also along their solid-liquid interface. In particular, we reveal a mechanism in which grain boundaries couple with the solid-liquid corrosion front to promote rapid dealloying and molten salt attack. Oxidant content in the salt and double-layer formation at the interface are discussed for their roles in setting the electrochemical potential and reaction rate at the metal-salt interface. Finally, we discuss how the model leverages insights from atomistic modeling and highlight key knowledge gaps in the mesoscale modeling of electrochemical molten salt corrosion.