bluuebunny/crossref_metadata_2025 huggingface dataset:
Recycling of PFSA-Based Membranes and Their Re-Application in PEM Fuel Cells
Authors: Kutter Maximilian , Greve Christopher , Rosin Andreas , Herzig Eva M. , Gerdes Thorsten , Roth Christina
Published: September 2023

The commercialization of PEM fuel cells offers a promising opportunity to overcome our dependence on fossil fuels and provides an attractive alternative for automotive and stationary power applications.[1] However, PEMFCs are still costly in production, with the main cost factor due to the fabrication of the perfluorosulfonic acid (PFSA)-based proton exchange membrane and the noble metal catalysts.[2,3] Recycling of these components could increase the economic attractiveness of PEMFCs. However, while the high resistance of the ionomer membrane to thermal and chemical degradation is favorable for their use in fuel cells, it also makes membrane recycling a major challenge.

Here, we present a newly developed recycling strategy to recover PFSA-based membranes after operation by a hydrothermal treatment. Both short side chain (SSC) and long side chain (LSC) ionomers with EWs of 800 and 1000 were investigated. In contrast to previously published methods, we were able to recover the PFSA ionomer by using water instead of high-boiling organic solvents, such as DMF or DMSO.[4,5] The recycled membranes were obtained from the recycled PFSA ionomer solution by doctor-blading. They were investigated by in-situ Raman techniques for studying the water uptake and analyzed by IR and small-angle X-ray scattering (SAXS) techniques to get a more detailed insight into their morphology. In single cell tests at standard (80 °C) and enhanced (up to 130 °C) PEMFC operating temperatures, the recycled membranes showed an increased cell performance as compared to the pristine 3M-800EW membrane. Solid-state NMR measurements confirmed that no chemical changes in the membrane occurred due to the heat-treatment process.

We assume that the observed performance boost can be attributed to an increased water uptake and retention. Furthermore, a change in the polymer matrix formation may be responsible for the observed behavior, which led to an expanded water filled channel structure, where water can accumulate to facilitate proton diffusion as H3O+ through the channels. To confirm this assumption, the morphology of the recycled membranes will be investigated by in situ SAXS measurements at different temperatures and degrees of hydration.

[1] I. Staffell, D. Scamman, A. Velazquez Abad, P. Balcombe, P. E. Dodds, P. Ekins, N. Shah, K. R. Ward, Energy Environ. Sci.
2019, 12, 463–491.

[2] J. Fan, M. Chen, Z. Zhao, Z. Zhang, S. Ye, S. Xu, H. Wang, H. Li, Nat. Energy
2021, 6, 475–486.

[3] D. Papageorgopoulos, Fuel Cell R&D Overview. 2019 Annual Merit Review and Peer Evaluation Meeting, 2019.

[4] Q. Xu, X. Chen, S. Wang, C. Guo, Y. Niu, R. Zuo, Z. Yang, Y. Zhou, C. Xu, Energies
2022, 15, 8717.

[5] H. F. Xu, X. Wang, Z. G. Shao, I. M. Hsing, J. Appl. Electrochem.
2002, 32, 1337–1340.
(Invited) Lithium Tetrafluoroborate Based Ester Electrolyte System for Wide Operating Temperatures Ingraphite/ Lini 0.6 Co 0.2 Mn 0.2 O 2 Cells
Authors: Jayawardana Chamithri , Rodrigo Nuwanthi Dilhari , Lucht Brett L.
Published: September 2023

As Lithium ion batteries (LIB) are utilized in wider scale of applications, operation at a wide range of operating temperatures without a penalty to the energy density is desired. Current LIB only produces a fraction of the room temperature capacity when operated at subzero temperatures. Optimization of the electrolyte composition has long been considered a way of improving low temperature battery performance, as the electrolyte dictates the ionic mobility and the stability of the solid electrolyte interface (SEI), which in turn determine the Li ion intercalation kinetics and cycle life of the cell. Different operating temperatures has different demands from the electrolyte. For room temperature performance, formation of a stable solid electrolyte interface is thought to dictate the capacity and the cycle life of a cell. For low temperature performance, Li ion transport properties and charge-transfer polarization may have a dominant effect on cycling performance. Therefore, in this work, a novel electrolyte system was developed that included lithium tetrafluoroborate and methyl acetate for good low temperature performance and different additives were incorporated to this system to improve the room temperature performance by formation of a stable SEI.
Oxidative Desorption of Adsorbed Sulfur on Platinum Surfaces Modified with Cerium Species
Authors: Morooka Tetsuro , Nakanishi Takuya , Masuda Takuya
Published: September 2023

In polymer electrolyte membrane fuel cells, hydrogen oxidation and oxygen reduction reaction occur at platinum (Pt) catalyst surface. Pollutants in air and hydrogen fuel, especially, sulfur (S) species, often strongly adsorb on the Pt surface, resulting in reduced electrochemically active surface area, namely poisoning effect. Because such poisoning causes the significant deterioration of cell performance and durability, understanding and control of adsorption behavior of S species are very important. Thus, it is necessary to develop a new method or material for recovery from S poisoning in anode.

In this study, a Pt(111) single crystal electrode was modified with a Ce species and its electrochemical property was compared with a bare Pt electrode. The modification with Ce species was accomplished by immersion in a Ce (NO3)3 + HClO4 aqueous solution with bubbling Ar + H2 gas through the solution for 1 h or applying the potential at -0.2 V in a Ce (NO3)3 + HClO4 aqueous solution. The modification of Pt(111) electrode with Ce species drastically changed the electrochemical responses; hydrogen adsorption/desorption waves become smaller and adsorption/desorption waves of hydroxy group disappeared because of the presence of adsorbed Ce species. Adsorbed species was identified as a Ce3+ ion by XANES spectrum.

After the bare Pt(111) electrode was immersed in an aqueous solution containing sodium sulfide, three types of adsorbed S species, HS and S/Sn were detected by XPS. HS was reductively desorbed from Pt electrode surface at potential cycling between 0.0 and 0.2 V vs. RHE (-0.2 and 0.0 V vs. Ag/AgCl). S/Sn species remained during this potential cycling but oxidatively desorbed when the positive limit of potential cycling was 0.6 V vs. RHE (0.8 V vs. Ag/AgCl). The hydrogen adsorption/desorption current gradually increased as repeating potential cycling between 0.0 and 1.0 V vs. RHE (-0.2 V and 0.8 V vs. Ag/AgCl).

After the Ce-modified Pt(111) electrode was immersed in an aqueous solution containing sodium sulfide, an anodic current assignable to the oxidative desorption of S species appeared at 0.3 V. The peak current decreased as repeating potential cycling between 0.0 and 0.7 V vs. RHE (-0.2 V and 0.5 V vs. Ag/AgCl). After this potential cycling, the peak area of S2p region of XPS spectra decreased as well as Ce 3d peak. The oxidative desorption of S and Sn on the Ce-modified Pt(111) electrode took place at 0.5 V vs RHE (0.3 V vs. Ag/AgCl) which is much more negative than that of bare Pt(111) electrode (1.0 V vs. RHE (0.8 V vs. Ag/AgCl)). Thus, modification of Pt(111) electrode with Ce species promoted the oxidative desorption of S species.
(Invited) Recent Development of Electrochemical Nitrate Reduction
Authors: Lim Jeonghoon , McCloskey Bryan D. , Lee Seung Woo , Hatzell Marta
Published: September 2023

Understanding the complexities of nitrogen cycle is critical because when the cycle is not in balance, excess reduced and oxidized nitrogen compounds could result in harmful impacts to life. Electrocatalytic conversion of waste nitrate (NO3
-) to benign dinitrogen (N2) and ammonia (NH3) fuel is an appealing strategy that may easily integrate with renewable energy. The process does not require chemical addition and thus requires operating costs lower than thermal routes. Nearly all nitrogen-based fertilizers rely on ammonia as a feedstock, and thus the demand for this chemical is heavily dependent on the global population and food demand. Over the next three decades, the global population will continue to dictate the market size and value for ammonia, which consequently will have a significant impact on our energy infrastructure. While electrochemical nitrogen reduction reaction (NRR) requires multiple proton and electron transfer process, ammonia production from nitrate reduction (NO3RR) is catalytic easier than NRR because the adsorbed/activated ion reactants (nitrate and nitrite) have an advantage of a lower dissociation energy for the N−O and N=O bonds (204 and 607 kJ mol-1) than that of N≡N bond (941 kJ mol-1). The synergistic effect between Cu and Pd has shown a high nitrate conversion yield and nitrogen selectivity. Engineering the Pd and Cu sites is critical but examination of the use of secondary metals in shape-controlled nanoparticle and atomic reconstruction are rare.

Here, we controlled Cu surface coverage on Pd nanocube nanoparticle to steer the selectivity between nitrogen and ammonia. In addition, the engineered the atomic structure of Pd and Cu nanoparticles showed high nitrate conversion yield, excellent dinitrogen selectivity, and outstanding cyclic stability. This study provides insights into the rational design of NO3RR electrocatalyst for efficiently transforming nitrate into nitrogen and ammonia.
Experimental Design for Accurate Reporting of Catalyst Activity in Nitrogen Reduction Experiments: Determination of the Optimal Membrane for Ammonia Retention
Authors: Wilder Logan , Wyatt Keenan , Parimuha Makenzie , Young James L. , Miller-Link Elisa
Published: September 2023

Ammonia synthesis from dinitrogen provides a critical feedstock to agriculture worldwide. The dominant process for ammonia synthesis, Haber-Bosch, is fossil-fuel dependent, energy intensive, and highly centralized. Electrochemical nitrogen reduction (ENRR) could provide a decentralized and environmentally friendly route to ammonia synthesis. ENRR research is challenging due to low amounts of ammonia produced in a typical experiment relative to environmental levels. In the first part of this presentation, we will share a critical result in ENRR experimental design which significantly improves the retention of generated ammonia, specifically related to the selection of membrane separators for H-cell or gas diffusion electrode cell platforms. This result is applicable to both dinitrogen and nitrate reduction research. In the second part of this presentation, a VS2-based ENRR catalyst, which has experimentally shown promising activity and selectivity, will be presented. Additionally, the proposed mechanism of ENRR on VS2 will be discussed, and we will discuss density functional theory simulation of ENRR on VS2 and MoS2. Finally, we will address areas of opportunity for ENRR.
Understanding Temperature and Pressure Effects of Lithium-Mediated Nitrogen Reduction
Authors: Chang Wesley , Song Hee Jo , Manthiram Karthish
Published: September 2023

Ammonia is a critical industrial commodity due to its importance for fertilizers, but the Haber-Bosch process for ammonia synthesis generates significant carbon emissions. A lithium-mediated electrochemical route towards ammonia synthesis has been developed and validated. Nitrogen transport through nonaqueous electrolytes and the resulting solid-electrolyte-interphase microstructure and chemistry are important factors in determining ammonia selectivity. Here, I describe efforts to understand the operating temperature and pressure effects on lithium-mediated nitrogen reduction. Pressure and temperature are tuning knobs that affect nitrogen transport, electrolyte properties, solid-electrolyte-interphase chemistry and lithium microstructure. By changing pressure or temperature, we can drive the system towards nitridation over parasitic hydrogen evolution. This helps to better understand various kinetic, thermodynamic and transport dependencies of the lithium-mediated nitrogen reduction reaction.
Ammonium Recovery from Manure Wastewater and Simultaneous Electrosynthesis Using Ammonium-Ion Selective Redox Material
Authors: Wang Rui , Yang Kai , Qin Mohan , Jin Song
Published: September 2023

The environmental pressure due to greenhouse gas emissions and water contamination generated by livestock manure motivates the development of new approaches to reduce their environmental impacts and improve sustainability. Effective approaches to recover nutrients, especially ammonium, from manure wastewater to produce fertilizer are needed. Here we develop a new electrochemical strategy to achieve simultaneous ammonium recovery and electrochemical synthesis using potassium nickel hexacyanoferrate (KNiHCF) as the ammonium ion-selective redox material to mediate the processes. The KNiHCF electrode spontaneously uptakes ammonium (and K+) from manure wastewater with a nutrient (NH4
+ and K+) selectivity of ~100% and effective reduction of chemical oxygen demand (COD). The subsequent electrochemical process achieves the co-production of NH4
+-rich fertilizers and value-added chemicals, such as H2 as a green fuel and H2O2 as a disinfectant, without expensive ion-exchange membranes. These results provide a new conceptual strategy and insights for distributed electrochemical resource recovery and on-demand electrochemical manufacturing that can improve agricultural sustainability.
(Digital Presentation) SOFC - Enabler for Highly Efficient Power Generation
Authors: Reiter Bernd
Published: September 2023

SOFC technology offers power generation with very high efficiencies > 60 %. This leads to a high future demand for decentralized power generation for a secure energy supply.

Based on the current extreme load shedding in South Africa, the SOFC System industrialization between AVL and Mitochondria will be presented.

In addition, SOFC in marine applications will be discussed:

In April 2018, the IMO Marine Environment Protection Committee (MEPC) adopted a first strategy to reduce greenhouse gas emissions from international shipping. The first strategy defined the following targets: Reduce CO2 emissions by 40% by 2030 and by 70% by 2050 compared to 2008 levels, and reduce total greenhouse gas emissions from shipping by at least 50% by 2050.

For some applications, fuel cell technologies for propulsion and auxiliary power are seen as one of the most promising solutions to achieve not only decarbonization but also other emission reduction targets in maritime transport. Fuel cell systems are considered serious competitors to internal combustion engines for several reasons: high electrical efficiency of 60% at about 25% load, low emissions, and nearly silent operation
An Atomic Scale Simulation Framework to Decipher the Complex, High-Temperature Solid Oxide Electrolysis Cell Electro-Chemistries
Authors: Hossain Md Jamil , Pawar Gorakh Machindranath , Gaikwad Prashik , Shin Yun Kyung , Schulze Jessica , Penrod Kate , van Duin Adri
Published: September 2023

Solid oxide electrolysis cells (SOECs) have received a significant attention due to their high

hydrogen (H2) generation efficiency. However, the major scientific challenges such as low

faradaic efficiency of SOECs affects the costs per kilogram of H2 and the large-scale adoption of

H2 as a fuel. Therefore, it is imperative to address the fundamental issues surrounding the low

faradaic efficiency bottleneck and pave the way for a better SOEC design with a relatively higher

faradaic efficiency. In the present research, we present eReaxFF atomic scale simulations

workflow that can reproduce quantum mechanical (QM) calculations on relevant condensed

phase and cluster systems of solid oxide materials describing oxygen vacancies, vacancy

migrations, water adsorption, water splitting and hydrogen generation on the solid oxide material

surfaces in a typical electrocatalysis process. We used barium zirconate doped with 20 mol% of

yttrium (BZY20) solid oxide as model system. Using the developed eReaxFF force field, we

performed zero-voltage molecular dynamics simulations to observe water adsorption and the

steps leading to the eventual hydrogen production. In addition, the introduction of explicit

electron concept to the force field led to the understanding of the non-zero-voltage effects on

hydrogen generation. Based on our simulation results, we conclude that this force field opens an

avenue to simulate electron conductivity, electron leakage and provide us a far-reaching

molecular understanding of improving the faradaic efficiency of SOECs.
Enhancing Power Density of Proton Exchange Membrane Fuel Cells for Mobile Applications By Designing Hybrid Flow Fields
Authors: Kim Choeun , Na Youngseung
Published: September 2023

Proton exchange membrane fuel cells (PEMFCs) are a promising alternative to internal combustion engines for reducing greenhouse gas emissions. The PEMFC stack consists of bipolar plates, gas diffusion layers, membrane electrode assemblies, and gaskets. Bipolar plates, which are directly related to volumetric power density, affect the supply of reactants, removal of products, and electron conduction. Practical flow field plates are hundreds of square centimeters in size and responsible for the uniform distribution of the reactants. The well-designed distribution area of the flow field, which is not involved in the electrochemical reactions, increases the current density of the fuel cell but lowers the volumetric power density. This study aims to maximize volumetric power density by improving reactant distribution and reducing the distribution area. A hybrid flow pattern, combining parallel and serpentine flow paths, uniformized flow to each channel without widening the distribution area. Computational fluid dynamics was used to evaluate the effect of distribution area and channel design on fuel cell performance. The polarization curve of the unit cell shows that the hybrid flow field evenly distributes the reactant gas, resulting in a 39% increase in current density and a 28% reduction in the flow rate deviation of the flow rate supplied to each channel. These results demonstrate a significant improvement in the power density of PEMFC stacks using the proposed hybrid flow field design. Overall, the hybrid flow field can be a cost-effective option as it requires less platinum catalyst to achieve the same power density.
Technology Development for Hydrogen Production Using Nuclear Energy
Authors: Li Hongqiang , Stolberg Lorne , Patel Jayesh , Ibeh Blessing , Vega Adrian , Suppiah Sam
Published: September 2023

Nuclear energy is a low-carbon energy source which can provide both electricity and high-temperature heat. Nuclear-based hydrogen production offers a unique opportunity to mitigate carbon emissions. Canadian Nuclear Laboratories (CNL) has been actively developing technologies for nuclear hydrogen production. This poster will highlight CNL’s capability and achievements on the Cu-Cl thermochemical process (CNL trademarked as HCuTECTM) and Solid oxide electrolysis (SOE).

HCuTECTM has four main steps in the process: Electrolysis, Separation, Hydrolysis and Thermolysis. The maximum temperature of the HCuTECTM process is 530 oC, which is lower than other thermochemical processes and makes its coupling with some small modular reactors and the supercritical water nuclear reactor ideal since these reactors can supply heat above 600 oC. CNL has extensively studied these individual steps and demonstrated an integrated laboratory system (shown in Figure 1) with a hydrogen production capacity of 100 g/d. CNL is interested in scaling up the process with industrial partners.

SOE is also being researched and advanced for hydrogen and clean fuel production at CNL. Current effort is focused on the materials development for oxygen conducting cells. Several CNL cells were made with in-house materials and tested on single cell stations. Preliminary results of CNL cells showed very promising performance for hydrogen production. In the meantime, CNL is assessing the economic benefit of different options to integrate SOE with high-temperature nuclear reactors for both hydrogen and clean fuel production.

Figure 1
Electro-Oxidative Polymerization of Aromatic Monomers without an Electric Power Supply
Authors: Inagi Shinsuke , Iwai Suguru
Published: September 2023

Electrochemistry is a powerful tool for organic synthesis based on electron transfer-driven reactions at the substrate/electrode interface. The use of electricity for synthetic reactions without the need for hazardous chemical oxidants and reductants is recognized as a green and sustainable approach. We have recently developed a split bipolar electrode (s-BPE) system [1], in which the redox reactions can be driven in a low electrolyte concentration, with batch [2,3] and flow [4] cells. Herein, we report a novel s-BPE system for organic electrosynthesis driven under a streaming potential condition with a pressure flow. As a proof-of-concept study on electrosynthesis without an electric power supply, electrochemical oxidative polymerization of aromatic monomers such as pyrrole successfully yielded the corresponding polymer films on an electrode surface at the upstream, which acted as an anode [5].

[1] Shida, N.; Zhou, Y.; Inagi, S. Chem. Res.
2019, 52, 2598-2608.

[2] Miyamoto, K.; Nishiyama, H.; Tomita, I.; Inagi, S. ChemElectroChem
2019, 6, 97-100.

[3] Shida, N.; Villani, E.; Sanuki, M.; Miyamoto, K.; Gotou, A.; Isogai, I.; Yamauchi, A.; Fuchigami, T.; Tomita, I.; Inagi, S. Electrochemistry, 2021, 89, 476-479.

[4] Sakagami, H.; Takenaka, H.; Iwai, S.; Shida, N.; Villani, E.; Gotou, A.; Isogai, T.; Yamauchi, A.; Kishikawa, Y.; Fuchigami, T.; Tomita, I.; Inagi, S. ChemElectroChem, 2022, 9, e202200084

[5] Iwai, S.; Suzuki, T.; Sakagami, H. Miyamoto, K.; Chen, Z.; Konishi, M.; Villani, E.; Shida, N.; Tomita, I.; Inagi, S. Commun. Chem., 2022, 5, 66.
Development of a Small Molecule Hydrogen Evolution Catalyst
Authors: Karr Dylan Thomas Mills , Pochkhua Luka , Staley Rachel , Smith Diane
Published: September 2023

Based on prior work done by Diane K. Smith et al on redox responsive 3 hydrogen bond array dimers, a fundamental investigation on the nature of proton coupled electron transfer (PCET) was done by surveying a series of new electroactive “host” H-bond dimers. In these dimers, electron transfer should induce proton transfer across a H-bond, increasing the overall strength of hydrogen bond binding the “guest” and “host”. In particular, the goal was to investigate how electrochemical behavior and binding strength changes as the relative acidity of the electro-inactive “guest” changes in a 2-hydrogen bond array. For this task, amido pyridinium derivatives will be used as the redox active "hosts" and a series of different carboxylic acid, 2-hydroxypyridine, and amide derivatives as the electro-inactive "guests". Unexpectedly, in the presence of carboxylic acids, the amido pyridinium acts as a hydrogen evolution catalyst. During guest host cyclic voltammogram (CV) titrations, there was a large anodic shift of 500 mV and a catalytic increase in current, which is characteristic of an EC mechanism (figure 2). A series of investigations into this mechanism were done following the initial discovery, including scan rate and concentration dependence CV’s, spectro-electrochemical studies, bulk electrolysis, DEMS, and DFT calculations. These studies allowed us to propose the mechanism below (figure 1) for hydrogen evolution. This presentation will detail our efforts to characterize this hydrogen evolution catalyst, the relevance of small molecule hydrogen evolution catalyst, and how we intend to modify it for synthetic purposes.

Figure 1 (left image): Reduction of pyridinium amide with and without guests and proposed mechanism of hydrogen evolution

Figure 2 (right image): CV of pyridinium amide in the presence of dodecanoic acid

Figure 1
Anodic Oxidation of 9,9'-Spiro Bifluorenes
Authors: Becker James Y. , Golub Tatiana , Herath Ajith , West Robert
Published: September 2023

Previously we investigated electrochemical properties [1] of various 2,3,4,5-tetraphenylsiloles (I) with different substituents attached to the Si atom. Major products include 1,2-dibenzoyl, 1,2-diphenylethene, tetraphenylfuran and tetraphenyldihydrofuran.

Later [2] we explored the redox properties of four silafluorenes of type (II). Major products after CPE involve both aromatic hydrocarbons and siloxane derivatives.

Recently [3] we studied the electrochemical redox properties of four spiro-derivatives (III) in which the central atom is C, Si, Ge or Sn, both by cyclic voltammetry and controlled potential electrolysis. The outcome from these measurements will be presented in this talk. It is noteworthy to indicate that each spiro derivative afford different products although their cyclic voltammograms are similar.

References

[1] A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem.,
2004, 569, 15-22; A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem.,
2004, 573, 139-146.

[2] A. C. Herath, R. West, J.Y. Becker, J. Electroanal. Chem., 2014, 728, 118-122.

[3] T. Golub-Sedinkin, A. C. Herath, R. West, and J. Y. Becker, ChemElectroChem
,
2019, 6, 1–6; J.Y. Becker, unpublished results (2021).

Figure 1
Electrochemical Upcycling of Pollutants
Authors: Waldvogel Siegfried R
Published: September 2023

The electrochemical conversion of pollutants provides a new and powerful way to upcycle these harmful substances into valuable intermediates. Electrosynthesis represents a future technology, which is characterized by its outstanding sustainability.[1] After carbon dioxide, sulfur dioxide is the most prominent pollutant in flue gas. The direct electrochemical incorporation into more elaborated molecules has started recently.[2] The anodic conversion of arenes and subsequent reaction with sulfur dioxide adducts yield sulfonamides,[3] sulfonates,[4] and sulfamides.[5]

Another pollutant from the era of highly chlorinated pesticides is hexachloro-cyclohexane. The non-suitable isomers of Lindane were piled-up in larges deposits ranging >7 Mio. t. By e-shuttle this can be converted to non-fossil benzene source.[6]

The talk will discuss in detail the mechanistic details which led to greener processes.

References:

[1] D. Pollok, S. R. Waldvogel, Chem. Sci.
2020, 11, 12375–12592.

[2] S. P. Blum, K. Hofman, G. Manolikakes, S. R. Waldvogel, Chem. Commun.
2021, 57, 8236–8249.

[3] S. P. Blum, T. Karakaya, D. Schollmeyer, A. Klapars, S. R. Waldvogel, Angew.
Chem. Int. Ed.
2021, 60, 5056–5062.

[4] S. P. Blum, D. Schollmeyer, M. Turks, S. R. Waldvogel, Chem. – Eur. J.
2020, 26, 8358–8362.

[5] S. P. Blum, L. Schäffer, D. Schollmeyer, S. R. Waldvogel, Chem.
Commun. 2021, 57, 4775–4778.

[6] X. Dong, J. L. Röckl, S. R. Waldvogel, B. Morandi, Science,
2021, 371, 507–514.

Figure 1
Meat Proteins and Electron Donors: Electrochemistry with Spectrophotometry
Authors: Kasthuri Dias Sandun Bogahawaththa , Kumar Rishav , Ramanathan Ranjith , Krishnan Sadagopan
Published: September 2023

The red color of meat is influenced by the proportion of oxymyoglobin to metmyoglobin presence. The greater the oxy/met ratio, the brighter the red color. We present here the voltammetric properties of beef myoglobin and relate them to the meat color attributes. Specifically, the storage stability of meat probed by changes in the electrochemical properties of meat proteins and the effect of electron donors on metmyoglobin reduction and oxy-myoglobin formation will be discussed.
(Invited) Electroenzymatic Hydrogen Production: Mediated/Direct Electron Transfer Strategies and Continuous Product Analysis
Authors: Milton Ross
Published: September 2023

Metalloenzymes such as hydrogenases and nitrogenases are of interest to electrochemists for mechanistic study as well as applied biotechnological hydrogen and ammonia production. In order to interface these enzymes with electrodes mediated and direct electron transfer methods have been reported, each having their strengths and weaknesses. In addition to establishing efficient electron transfer with enzymes, dynamic product analysis is also desirable since rates of product formation (and the distribution of products) can be determined during an experiment with varying electrode potential (and thermodynamic driving force for heterogeneous electron transfer).

Our recent efforts concerning the design of electrode:enzyme interfaces are presented here, including (i) mediated vs. direct electron transfer strategies, (ii) rotating ring disk electrochemistry, and (iii) continuous mass spectrometry and gas chromatography [1-2]. In this work, an [FeFe]-hydrogenase is employed as a model enzyme for molecular hydrogen formation, with a view to expand these approaches towards enzymatic electrocatalytic studies of nitrogenases. Limitations and difficulties of the presented approaches will be discussed.

References:

[1] Khushvakov, J., Nussbaum, R., Cadoux, C., Duan, J., Stripp, S.T. and Milton, R.D., Angewandte Chemie International Edition, 2021, 60 (18), 10001-10006.

[2] Liu, Y., Webb, S., Moreno Garcia, P., Kulkarni, A., Maroni, P., Broekmann, P. and Milton, R.D., Submitted.
Leveraging Commercial Microfluidic Chips for Zeta Potential Characterization
Authors: Cottet Jonathan , Oshodi Josephine , Yebouet Jesse , Furst Ariel L , Buie Cullen R
Published: September 2023

Bacteria zeta potential, ζ, is one of the key parameters for the deposition of bacteria on an electrode, also called electrophoretic deposition (EPD) and depends on the strain, suspension composition and pH. Measuring directly with a zetasizer is challenging due to the non-spherical shape of bacteria and the need for a lower conductivity medium which could affect the value of ζ. Electrokinetic measurements are usually performed with microchannels in PDMS [1] or in PMMA [2], both of which require expensive tools for the fabrication of either the mold or the microchannel itself. Reducing the cost and time needed to perform such measurements would enable the broader use of this technique. We anticipate solving this challenge with commercially available microfluidic chips as will be outlined in this study.

Under an electric field E in a microchannel, the electrokinetic velocity of particles in a fluid is linked to two phenomena: electrophoresis (EP) due to the zeta potential of the particle and electroosmosis (EO) due to the zeta potential of the channel wall. PMMA microchannels (Microfluidic ChipShop) with 200 µl reservoirs together with a voltage sequencer (Labsmith) controlled with LabVIEW were used to characterize the velocity of 1 µm and 2 µm polystyrene beads with different surface functionalizations (nonfunctionalized polystryrene (PS), Sulfate-modified (SU-modified), Carboxylate-modified (CO-modified) and Amine-modified (AM-modified) from Invitrogen and Magsphere suspended in 10 mM HEPES (pH 7) by applying different voltages between the inlet and outlet platinum electrodes for 90 s. Recorded time-lapse fluorescent image sequences were analyzed with ImageJ and TrackMate. Electrokinetic velocities obtained by Particle Tracking Velocimetry (PTV) at different voltages were fitted with a linear fit with a high coefficient of determination allowing the extraction of the different particle zeta potentials, which are in good agreement with the control measurements performed with a Zetasizer Ultra (Malvern Panalytical) [3]. Further, this methodology was used to characterize a prevalent strain of E. coli, yielding values in agreement with the literature.

The use of commercially available microfluidic chips in electrokinetic characterization could alleviate the need for microfabrication and allow the wider adoption of this characterization method. These measurements are ultimately critical to better understand the role of the zeta potential in EPD of microbes for an array of applications.

[1] S. Antunez-Vela, et al., Anal Chem, 2020

[2] Q. Wang et al., Science Advances, 2019

[3] J. Cottet, et al.
In preparation
Spatially Multiplexed Electrochemical Sensors for Detection of Respiratory Diseases
Authors: Zhou Xingcheng , Furst Ariel L
Published: September 2023

Infectious respiratory diseases, such as COVID-19 and influenza, pose a disproportionate burden on those who live in low resource settings (LRS). A key driver of this inequality is the lack of access to testing and diagnostics. Without centralized laboratories capable of testing patient samples, carriers cannot be easily identified and treated, leading to spread. The gold standard diagnostics often require expensive reagents, equipment, and trained personnel that are difficult to deploy in LRS. Electrochemical biosensors, which combine biorecognition elements with electrochemical readout to enable sensitive and specific sensing using inexpensive, simple equipment, are a major area of research for the development of “point-of-care” (POC) diagnostics that can be utilized in LRS. However, even these platforms remain limited, as some electrodes require fabrication in cleanrooms. In this talk, I describe a spatially-multiplexed electrode fabricated on benchtop from inexpensive gold leaf for the detection of multiple respiratory infections.
Electrochemical Ethylamine Dehydrogenation to Acetonitrile on Platinum-Based Catalysts
Authors: Wu Dezhen , Li Jialu , Tang Jinyao , Peng Zhenmeng
Published: September 2023

Hydrogen storage is a crucial link between green hydrogen generation by water electrolysis and hydrogen application in fuel cells. We very recently reported a new, electrochemical ethylamine/acetonitrile redox method for hydrogen storage [1]. This method realizes hydrogen uptake by pairing acetonitrile hydrogenation to ethylamine reaction (AHR) on cathode and hydrogen oxidation reaction (HOR) on anode, and realizes hydrogen release by pairing ethylamine dehydrogenation to acetonitrile reaction (EDR) on anode and hydrogen evolution reaction (HER) on cathode. With 8.9 wt.% theoretical storage capacity and ambient reaction conditions being demonstrated in the study, this method shows a great potential to advance hydrogen storage technology and meet the DOE target. One remaining challenge of this method was a rapid activity decay of the used commercial platinum catalyst (Pt/C) in the EDR, which caused a long-term durability issue.

In this work, we report our fundamental study of Pt catalyst deactivation mechanism in EDR and the discovery of new Pt-based catalysts. Attenuated total reflection infrared spectroscopy (ATR-IR) was employed for characterizing working catalyst surface under reactive conditions. Partially dehydrogenated intermediate species were observed to generate on Pt surface, which strongly adsorbed and caused an accumulation and blockage of the active sites. Interestingly, the catalyst showed a self-cleaning property where the intermediates can be hydrogenated back to ethylamine and released from Pt surface below 0 V vs. RHE. A group of Pt-Ni alloy catalysts were prepared and investigated the composition effect in this reaction, among which Pt3Ni exhibited 75% higher activity and significantly improved stability compared to Pt. ATR-IR experiments showed that the accumulation of intermediates on the Pt3Ni surface was much slower than that on the Pt, attributed to weakened adsorption. This work provides mechanistic insights into EDR reaction pathways and the cause of Pt catalyst deactivation and offers a Pt alloy strategy for active and stable catalyst design.

[1] Wu, D.; Li, J.; Yao, L.; Xie, R.; Peng, Z. ACS Appl. Mater. Interfaces 13, 55292 (2021).
Electrodeposition of Platinum-Transition Metal Alloys for Magnetic Thermometry
Authors: Rus Eric D , de Lima Corrêa Eduardo , Dennis Cindi L , Moffat Thomas P
Published: September 2023

The present work seeks to develop materials and structures with temperature-dependent magnetic properties providing optimal sensitivity for near-room temperature thermometry. Studies of the electrodeposition of Pt1-xMx (M=Ni,Co) alloys will be presented. The effects of boric acid and deposition potential on the deposition process and magnetic properties of Pt1-xNix and Pt1-xCox films will be compared. For Pt1-xNix, it was found that the presence of boric acid during deposition was accompanied by decreased Coulombic efficiency at more reducing deposition potentials, increased oxygen incorporation, and decreased magnetization relative to films deposited in the absence of boric acid.[1] Preliminary results for the Pt1-xCox system indicate its behavior is not simply analogous to the Pt1-xNix system.

[1] Rus, E. D.; L. Corrêa, E.; Groopman, E.; Williamson, T.; Hijazi, H.; Kasaei, L.; Dennis, C. L.; Moffat, T. P., Magnetic Characterization of Electrodeposited Pt1−xNix Alloy Films: Influence of Deposition Potential and the Presence of Boric Acid, J. Electrochem. Soc. 2022, 169 (9), 10.1149/1945-7111/ac8ad1.
Bidirectional Negative Coupling Induced Dynamical Patterns in a Branched Epoxy-Based Dual-Electrode Microchip Flow Cell
Authors: Tetteh John Anum , Kiss Istvan Z.
Published: September 2023

In this contribution, we investigated the spatiotemporal pattern formation of oscillatory electrodissolution of nickel in sulfuric acid with two micro-wires placed in two branches of a microfluidic flow cell. In the flow channel, the reference and counter electrodes are placed at the opposite end of the branched flow channel (contralateral placement). A theory based on modeling the potential drop in the flow channel and the interactions between the reactions showed the presence of bidirectional negative electrical coupling between the electrode potential variables. Experiments and numerical simulations with a kinetic model showed that such bidirectional negative coupling could induce complex dynamics. The experiments showed that anti-phase synchronization occurred only when electrodes were placed in the middle of the branched flow channel. When the electrodes were close to beginning or the end of the channels, where the reference and counter electrodes were placed, respectively, no phase locking was observed. The coupling is intensified in magnitude when the electrodes are in the middle of the flow channel, which maximizes the loop current which can flow towards the reference electrode. The nature of the bidirectional coupling is confirmed in independent experiments with synchrony analysis using the Hilbert transform. Additionally, to further verify the nature of the migration current coupling, a data driven approach, inferring connections of networks (ICON), was utilized. Analysis using the ICON technique showed that the synchronization patterns can be described by a phase repulsive bidirectional coupling. The findings indicate that contralateral placement should be used with great care in electroanalytical application with reactions that exhibit negative differential resistance(NDR) region, e.g., due to passivation or adsorption of an inhibitor. Ultimately, revealing connectivity is essential to characterize the dynamical structures and functions of networks, which in turn, leads to the fundamental understanding of many real-world complex systems such as the topology of the physical or functional connections of neurons in the brain.
(Invited) Interfacial Potential Distribution at Semiconductor/Liquid Interfaces: A Framework for the Quantitative Understanding of Voltammetric Data with Semiconductor (Photo)Electrodes
Authors: Maldonado Stephen
Published: September 2023

This presentation will introduce a quantitative framework for interpreting and analyzing voltammetric data from semiconductor (photo)electrodes immersed in liquid electrolytes. The basis of the approach is to use the dielectric properties of the semiconductor, electrolyte, and interfacial layer(s) to calculate explicitly the fractional potential drops across the system that occur when a bias is applied relative to an external reference. These fractional potential drops are then used to determine the potential dependences of the forward and back charge-transfer rates between the semiconductor and redox acceptors/donors of interest. These rates, in conjunction with mass transport considerations, are used to predict voltammetric shapes from a variety of useful experimental configurations including diffusing and adsorbed redox species at either semiconductor macro- or ultramicroelectrodes. The goal of the work is to understand semiconductor voltammetric data directly rather than through the (limiting) lenses of either metal electrode responses or solid-state diodes.

The presented framework assumes charge transfer occurs predominantly through the semiconductor band edges but a description of how contributions from surface states can affect the data will be discussed. In addition, this talk will also provide examples of how this framework improves the electroanalytical utility of semiconductor voltammetry to measure semiconductor surface reactions, the flat band potential, and interfacial dielectric properties.
(Invited) Solid-State Biophotoelectronics Using Photosystem I
Authors: Cliffel David E , Williams John , Stachurski Christopher D. , Jennings Kane , Galazzo Matthew
Published: September 2023

For the Grahame Award Symposium

Photosystem I (PSI) is one of the primary macromolecular machines that drive photosynthesis in green plants and cyanobacteria. Extracted PSI has been employed successfully as a macromolecular photosensitizer within a host of low-cost electrochemical and solid-state photovoltaic architectures. This presentation will also explore our group’s recent efforts to integrate PSI with advanced nanomaterials, including carbon nanotubes, carbon quantum dots, and conducting polymers polyaniline (PANI), polypyrrole, polyviologens, and poly(3,4-ethylenedioxythiophene) in wet photoelectrochemical cells. These composite assemblies enhance charge shuttling processes from individual proteins within multilayer assemblies—greatly reducing charge transfer resistances and improving overall efficiency of photocells. Recently, our group has reported two new prototype solid-state devices in which PSI or PSI/PANI is sandwiched between conducting polymer electrodes. The group has also succeeded in stabilizing PSI films via crosslinking to create “wet” photoelectrochemical cells with greater performance and longevity. Finally, our current work is aimed at building new prototypes using PSI in solid state interfaces for scalable solar energy conversion. Finally, the incorporation of PSI into conducting polymer frameworks holds promise for improved conductivity and orientational control in the photoactive layers in these devices.
(Invited) Designing Transport into Multifunctional Materials for Energy & Power
Authors: Rolison Debra R. , Long Jeffrey W. , Sassin Megan B. , DeSario Paul A. , Novak Travis G. , DeBlock Ryan H.
Published: September 2023

Designing electrodes and catalytic platforms as architectures in which the entire volume of the porous “reactor” is wired continuously in three dimensions for electron, ion, and molecular transport expands the reactive electrochemical and catalytic turf beyond the limited footprint imposed by a two-dimensional cross-section or a single three-phase boundary per supported nanoparticle. Amplifying the electron/ion/molecularly wired interfacial area by hundreds of square centimeters per cross-sectional square centimeter converts redox reactions that lose morphological control at high local current density into more uniformly reactive events that experience low local current density. Similar distributed arrangement of the reacting species in architected catalytic platforms imparts resilience of the supported catalyst. Aperiodic architectures such as foams and sponges effectively distribute the available reactive, electron/ion/molecularly wired interfaces while maintaining a co-continuous mapping of void and solid to facilitate ingress/egress of reactants and products. Examples from our work with electrode architectures show the power of controlling energy-storage reactions locally by distributing them within electron-wired high-surface interiors. The arrangement ensures that per area current remains low throughout the volume of the electrode, yet the electrified area sums to provide device-relevant current. The intimate interfacial contact we achieve for copper nanoparticles supported on ceria aerogels yields active, selective, and stable architected catalysts for preferential oxidation of carbon monoxide in hydrogen feedstreams.
(Physical and Analytical Electrochemistry Division David C. Grahame Award) Vignettes of Charge Transfer Processes at Interfaces Inspired By D.C. Grahame and Previous ECS Grahame Awardees
Authors: Stevenson Keith J.
Published: September 2023

I am very humbled to be recognized with the 2023 ECS David C. Grahame Award. My presentation will start with the acknowledgment that this award does not happen without all the efforts of students, post-doctoral fellows and colleagues over the past 30 years. Notably, the basis of all my graduate work was inspired by Grahame’s 1947 seminal work [1] on electric double layers at metal-solution interfaces. The study of “clean” pseudo-single crystalline silver electrodes enabled us to quantify and understand the electrochemical formation of stable monolayers of various anions and cations, e.g. [2,3]. In hindsight, also I recognize that these studies provided me with the fundamental underpinnings and motivations to study charge transfer processes in much more complicated semi-metal- and semiconductor-solution systems using a plethora of experimental methods during my academic career. As discussed long ago by Gerischer [4], the key distinction between metal-solution and semiconductor-solution interfaces is that the mechanisms of charge transfer processes can be divided into many groups, mainly with those with weak interactions and the reactants in the electrolyte and those with strong interactions. A more complicating factor with semiconductor-solution interfaces is that the charge-transfer process typically involves both reaction with the electrolyte and a change in the conductivity of the electrode, e.g. [5]. I will provide a series of vignettes (case studies) inspired by several previous ECS Grahame awardees of the distinctive features of different charge transfer processes and their relation to energy conversion, energy storage and chemical sensing applications.

[1] Grahame, D. C. Chem. Rev.
1947, 41, 441.

[2] Stevenson, K. J.; Gao, X.; Hatchett, D. W.; White, H. S. J. Electroanal. Chem.
1998, 447, 43.

[3] White, H. S.; Peterson, J.; Cui, Q; Stevenson, K. J. J. Phys. Chem. B
1998, 102, 2930.

[4] Gerischer, H. 1969, 18, 97.

[5] Nikitina, V. A.; Vassiliev, S. Yu; Stevenson, K. J. Adv. Ener. Mater.
2020, 1903933.