bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase-Field Modeling of Zinc Dendrite Growth in Aqueous Zinc Batteries
Authors: Jian Qinping , SUN Jing , Li Hucheng , Guo Zixiao , Zhao Tim
Published: August 2024

The growth of zinc dendrites poses a major challenge in developing stable aqueous zinc batteries. It is crucial to understand the mechanism underlying the dendrite growth and the influences of various factors on the process of dendrite growth. In this study, a phase field model is constructed to simulate the growth of zinc dendrite and investigate the temporal and spatial distributions of ions and electric potential in both static and flowing electrolytes. The influences of various critical factors, including overpotential, anisotropic strength and electrolyte flow rate, on the morphology evolution of electrodeposit are investigated. Results reveal that the surface morphology evolution is intimately dependent on the competition between ion transport and the electrochemical reaction, and it can be modulated by various parameters. In particular, flowing electrolyte not only enhances the convective ion transport but also suppresses the dendrite bifurcation on the surface, resulting in a uniform distribution of the concentration gradient and a compact deposit. However, nonuniformity induced by the flowing electrolyte from the inlet to outlet may impede the stable cycling of zinc anodes in the flow batteries. Therefore, further design and optimization of the flow field are desired for zinc-based flow batteries. This work provides insights into the growth process of zinc dendrites and the influences of several critical parameters, which could inform the design of stable aqueous zinc batteries.

Figure 1
A Water-in-Ester Electrolyte with Controllable Water Activity for Highly Reversible Zinc Anodes
Authors: Li Hucheng , Jian Qinping , Deng Chengfang , SUN Jing , Zhao Tianshou
Published: August 2024

Rechargeable aqueous zinc batteries, featuring intrinsic safety, low cost and terrific recyclability, are an emerging and engaging technology potentially for stationary energy storage. However, this technology is blocked by the instability of zinc anode/electrolyte interface, due to the water-induced hydrogen evolution and dendrite growth. Herein, we formulate a water-in-ester electrolyte to effectively regulate the water activity by controlling the molar ratio of H2O to γ-valerolactone. The γ-valerolactone gets in on the solvation of Zn2+ ions, helping to exclude almost all bound water molecules from the solvation shell, and interacts with free water via forming intermolecular hydrogen bonds, thus completely confining water molecules in γ-valerolactone network. Thanks to the constrained H2O molecules and the reduced water activity, Zn anodes exhibit heighted anti-corrosion abilities in the water-in-ester electrolyte compared with the pure water electrolyte. The zinc deposition morphology evolves from hexagonal dendrites to tense particles, as the pure water electrolyte is transformed to the water-in-ester electrolyte. Water-in-ester electrolytes as well promise less hydrogen production, and eventually improve the average columbic efficiency and cycling stability of asymmetric Zn ‖ Ti cell from less than 85% and merely 10 cycles to 99.6% and over 500 cycles. The cycling lifespan of symmetric Zn ‖ Zn cell is extended to more than 1100 h at 1 mA cm-2 and 1 mAh cm-2 with the water-in-ester electrolyte, fourfold higher than that of the pure water electrolyte. Additionally, superior full cell performance is demonstrated for the newly formulated electrolyte. This work sheds light on the strong correlation between water activity and performance of zinc anodes and contributes to developing more stable aqueous zinc batteries by restricting water activity.
Regulations of Bulk and Interfacial Chemistry of Mn-Based Cathode Materials for Sodium Ion Batteries
Authors: Cai Xinyin , Liang Li Xun , Bai Haobo , Shadike Zulipiya
Published: August 2024

Sodium ion batteries (SIBs) show the great potential to achieve large-scale energy storage due to their low cost and good safety as well as abundant resources of sodium. Among the cathode materials for SIBs, manganese-based layered oxides with adjustable structure have been attached great interest for the high energy density and low-cost SIBs. . Particularly, P2-type Mn-based materials exhibit anionic redox during charge and discharge processes, which can not only elevate the battery potential but also provide extra capacity, drastically boosting the energy density of the batteries. However, the irreversible phase transition, Jahn-Teller effect of manganese and interphase degradation at high charge cutoff voltage during anionic redox largely affect the cyclic stability of the cathodes. Therefore, it is essential to develop effective strategies to regulate the structural and interfacial chemistry for suppressing the phase transition and voltage hysteresis as well as increasing the cycle life of cathode materials. In this work, various electrochemical inert/active elements have been introduced into Mn-based P2 type cathode materials for regulating the electronic structure of the cathodes to promote more anionic redox and improve the structural stability. In addition, a new type of ionic liquid is introduced to build a stable interphase and improve the high voltage stability of the cathode material. Multi-model synchrotron-based X-ray characterization techniques combined with first-principles calculation are used to reveal the effectiveness of different strategies on the electrochemical properties of SIBs. The results provide valuable information for the development of high-performance cathode materials.

Acknowledgement

This work at Shanghai Jiao Tong University was financially supported by the National Natural Science Foundation of China (No. 22209106).
Effect of Electrolytes on Performance of Tire Derived Carbon for Sodium-Ion Batteries
Authors: Paranthaman M. Parans , Pethe Saurabh Prakash , Sun Xiao-Guang
Published: August 2024

Sodium-ion batteries (SIBs) have recently become prominent in the battery ecosystem due to their low cost and use of earth abundant materials such as Sodium, Manganese, Aluminum, Iron, and Prussian blue (iron cyanide). [1] Graphite is the standard anode used for LIBs but cannot be used in SIBs due to interlayer distance being too small to accommodate Na+ ion. Hard carbons are suitable candidates for SIB due to their low cost, low working potential, high capacity, and ability to be synthesized at lower pyrolysis temperatures. In our past work we have reported a low-cost, scalable waste tire-derived carbon as an anode for SIBs [2]. In this work we test the tire derived carbon with 6 different electrolytes and understand the impact each has on the performance. The best electrolyte was found to be sodium hexafluorophosphate in ethylene carbonate (EC)–ethyl methyl carbonate (EMC) (NaPF6-EC/EMC) which showed a capacity of 108 mAh/g after 200 cycles at charge/discharge rate of C/3. The initial columbic efficiency (ICE) was found to be 52% and to mitigate this problem we tried a scalable contact pre-sodiation method. The pre-sodiation method showed high initial columbic efficiency drastically improving capacity retention of the battery.

References

1. Li, F., et al., Sodium-based batteries: from critical materials to battery systems. Journal of materials

chemistry A, 2019. 7(16): p. 9406-9431.

2. Li, Y., Paranthaman, M.P., Akato, K., Naskar, A.K., Levine, A.M., Lee, R.J., Kim, S.O., Zhang, J.,

Dai, S. and Manthiram, A., 2016. Tire-derived carbon composite anodes for sodium-ion

batteries. Journal of Power Sources, 316, pp.232-238.
Characterization of the Design and Performance of Commercialized Sodium-Ion Batteries
Authors: Hirsh Hayley S , Holguin Kathryn , Bhattacharya Rajashree , Loewen Natalia D , Dienemann Lara , Ha Yeyoung , Bogart Timothy D , Beers Keith M
Published: August 2024

The escalating demand for energy storage solutions has spurred the commercialization of sodium-ion batteries (NIBs), prompting a paradigm shift from laboratory research to real-world applications. The success of commercial NIBs hinges on their ability to meet stringent performance metrics, ensuring competitiveness in the large-scale energy storage market. Manufacturing new cell chemistries is complex, and if the cells have design flaws and/or manufacturing defects it could hinder their performance and safety. We will present detailed findings of the NIB cell design, construction, and performance of commercialized 18650 format NIBs. The cell design and construction will be analyzed using 3D X-ray computed tomography and cell teardowns with materials analysis. In addition, the electrochemical performance of these cells will be investigated over a range of rates and temperatures. This study will provide insight into the quality and performance of some of the early to market commercialized NIBs and how it could affect their use in large scale energy storage.
Revealing the Path-Dependence of Catalyst Degradation in Polymer Electrolyte Fuel Cells
Authors: Cheng Lei , Rezaei Talarposhti Morteza , Braaten Jonathan , Khedekar Kaustubh , Zenyuk Iryna , Coats Matthew , Pylypenko Svitlana , Craig Nathan , Johnston Christina
Published: August 2024

Electro-catalyst plays a central role in many clean energy technology applications including water electrolysis for green hydrogen generation, emission free fuel cells for transportation, electrochemical CO2 reduction and combine heat and power generation. Electro-catalysts degrade via multiple mechanisms, depending on the exact operating conditions in its life cycles. In this presentation, we demonstrate the dependance of the electro-catalyst degradation in polymer electrolyte fuel cell (PEFC) on the specific “paths” that the fuel cell takes to age. Specifically, differently ordered aging protocols with the same total number of accelerated stress tests (ASTs) cycles (i.e., 31,000 total cycles including 30,000 cycles of square-wave load/unload ASTs and 1000 cycles of triangular-wave carbon corrosion ASTs) were used to degrade membrane electrode assemblies (MEAs). At the end-of-life, performances were distinct, indicating that depending on the specific aging route taken, the fuel cell catalyst layer degrades differently after same number of total AST cycles. The load/unload aging protocol led to more severe losses of performance when preceding after the carbon corrosion aging ASTs
(Invited) Nitrogen-Doped High-Entropy Alloy as Efficient and Stable Electrocatalyst
Authors: Zhao Xueru , Cheng Hao , Chen Xiaobo , Zhang Qi , Li Chenzhao , Xie Jian , Marinkovic Nebojsa S. , Ma Lu , Zheng Jin-Cheng , Sasaki Kotaro
Published: August 2024

The development of Pt-based catalysts for use in fuel cells that meet performance targets of high activity, maximized stability, and low cost remains a huge challenge. The high-entropy alloy (HEA) is one of the most promising candidates for electrocatalysts, owing to their unique properties involving the high entropy effect, lattice distortion effect, sluggish diffusion effect, and “cocktail” effect.1 Alternatively, nitrogen (N)-doping effects have been well documented and demonstrated in our previous studies, which further fine-tune the adsorption energetics of intermediates and improve the corrosion resistance by the pinning effect of metal-nitrogen bonds.2-3 Combining the HEA and N-doping strategies, the tailored lattice and interstice atomic sites lead to the formation of chemically stable multiple metal-nitrogen (M-N) bonds and the generation of the possible synergistic effect on promoting ORR performance. Herein, we report a N-doped high-entropy alloy (HEA) electrocatalyst that consists of a Pt-rich shell and a N-doped PtCoFeNiCu core on a carbon support (denoted as N-Pt/HEA/C). The N-Pt/HEA/C catalyst showed high mass activity of 1.34 A mgPt
-1 at 0.9 V for the oxygen reduction reaction (ORR), which substantially outperformed commercial Pt/C and most of the other binary/ternary Pt-based catalysts. The N-Pt/HEA/C catalyst also demonstrated excellent stability in both rotating disk electrode (RDE) and membrane electrode assembly (MEA) testing. Using operando X-ray absorption spectroscopy (XAS) measurements and theoretical calculations, we revealed that the enhanced ORR activity of N-Pt/HEA/C originated from the optimized adsorption energy of intermediates, consequent of the tailored electronic structure formed upon the N-doping. Furthermore, we showed that the multiple metal-nitrogen bonds formed synergistically improved the corrosion resistance of the 3d transition metals and enhanced the ORR durability.

References

Yao, Y.; Dong, Q.; Brozena, A.; Luo, J.; Miao, J.; Chi, M.; Wang, C.; Kevrekidis, I. G.; Ren, Z. J.; Greeley, J.; Wang, G.; Anapolsky, A.; Hu, L., High-entropy nanoparticles: Synthesis-structure-property relationships and data-driven discovery. Science
2022,
376 (6589), eabn3103.

Zhao, X.; Xi, C.; Zhang, R.; Song, L.; Wang, C.; Spendelow, J. S.; Frenkel, A. I.; Yang, J.; Xin, H. L.; Sasaki, K., High-Performance Nitrogen-Doped Intermetallic PtNi Catalyst for the Oxygen Reduction Reaction. ACS Catalysis
2020,
10 (18), 10637-10645.

Zhao, X.; Cheng, H.; Song, L.; Han, L.; Zhang, R.; Kwon, G.; Ma, L.; Ehrlich, S. N.; Frenkel, A. I.; Yang, J.; Sasaki, K.; Xin, H. L., Rhombohedral Ordered Intermetallic Nanocatalyst Boosts the Oxygen Reduction Reaction. ACS Catalysis
2020,
11 (1), 184-192.
Low-Electronegativity Mn-Contraction of PtMn Nano-Dendrite Boosts Oxygen Reduction Durability
Authors: Nie Yan , Zhao Chuan
Published: August 2024

Although proton exchange membrane fuel cells (PEMFCs) are emerging as an efficient and green technology, their heavy reliance on scarce and exorbitant price platinum catalysts for the oxygen reduction reaction (ORR) hampers large-scale commercialization1. The strain effect, induced through the alloying of Pt with transition metals, can enhance the catalytic activity as well as reduce the platinum loading2. While this has been well documented, these catalysts’ durability has received limited attention3. In this work, we report a new class of PtMn alloy catalysts with low-electronegativity Mn-contraction which boosts the oxygen reduction durability of fuel cells. X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) reveal that the PtMn catalyst with moderate strain shows the best activity (0.53 A mg-1 at 0.9 V RHE). The PtMn alloy catalyst achieves an outstanding mass activity retention of 96% after 10,000 degradation cycles in liquid electrolyte due to the low-electronegativity of Mn, with far superior performance than highly electronegative PtNi alloys. Finally, the PtMn catalyst in PEMFC achieves an outstanding peak power density of 1.4 W cm-2 using half the loading of commercial Pt/C, and good stability over 50 h at 0.6 V in H2-O2.

Figure 1
Enhancing Anode Reversal Tolerance by Low-Carbon and Carbon-Free Anode Catalyst Layers for Proton Exchange Membrane Fuel Cells
Authors: Li Zheng , Huang Haodong , Lin Xiao , Zhang Zijie , Zhao Tianshou , Zeng Lin
Published: August 2024

Proton exchange membrane fuel cells (PEMFCs), as the main hydrogen utilization device, are considered a powerful tool for accelerating a carbon-neutral society. However, durability and cost are the two main obstacles to the commercialization of PEMFCs. Specifically, the anode reversal has been extensively studied as a severe issue that deteriorates the performance and durability of PEMFCs and leads to cell failure. Commercially, iridium oxide (IrOx) or iridium black is intensively utilized as oxygen evolution reaction catalysts to fabricate reversal tolerant anodes (RTAs) despite the slight performance loss. However, previous studies concentrated on investigating the origin or phenomena during the cell-reversal, the key factors and mechanisms affecting the anti-reversal performance, and the interaction among the anode catalyst layer components are still yet to be explored.

Hence, we systematically studied the performance using three typical carbon supports with three metal contents and different metal deposition orders by experiments and model calculations. First, we synthesized Ir outside Ir/Pt/C and Pt outside Pt/It/C with uniform nanoparticle size and distribution and characterized them comprehensively. A new parameter, “relative metal coverage”, is put forward to evaluate and predict the anti-reversal ability, showing that higher relative metal coverage results in a longer reversal time and lower polarization performance degradation rate. In addition, Ir outside Ir/Pt/C shows better reversal tolerance than Pt outside Pt/It/C, which has been rarely mentioned in previous studies. Further, the experimental results show that even though the metal coverage is high, the performance degradation caused by carbon corrosion is still inevitable. On this basis, we synthesized a high specific surface area conductive oxide Ti4O7 as the anode catalyst support to eliminate the adverse effects of carbon corrosion. Previously, the initial performance of Ti4O7-supported catalyst was obstructed by the disadvantaged electrical conductivity of Ti4O7. We obtain a comparable polarization performance after optimizing the Ti4O7-supported anode catalyst layer parameters by shortening the electron transfer pathway and increasing metal coverage. Typically, the Ir@IrOx/Pt/Ti4O7-fabricated RTA with low Ir loading displays approximately ten times longer reversal time (6 hours) and two orders of magnitude lower degradation rate than a conventional carbon-supported counterpart. The degradation origin of the Ti4O7-supported anodes is also studied by postmortem characterizations, pointing to the Pt oxidation caused by the formation of TiOx thin layers on the Pt surface. These two works aim to promote the development of highly durable and reversal tolerance anode and provide a bright perspective for practical high-performance, low-degradation, and cost-friendly RTA fabrication.
Ag/CNT Catalyst Synthesized by Plasma-Enhanced Atomic Layer Deposition for Anion Exchange Membrane Fuel Cells
Authors: Park Jongseon , Seo Beum Geun , Koo Junmo , Han Gwon Deok , Prinz Fritz , Shim Joon Hyung
Published: August 2024

Anion exchange membrane fuel cells (AEMFCs) have recently gained attention as a viable alternative to proton exchange membrane fuel cells (PEMFC), offering the potential for high output without relying on expensive platinum (Pt) catalysts. PEMFCs operate in an acidic environment characterized by a high concentration of H+, necessitating the use of platinum-based catalysts to ensure both performance and stability in such conditions. In contrast, AEMFCs operate in an alkaline environment (OH-), affording the use of high-performance catalysts like silver (Ag), which is sensitive to acidity. Moreover, the cost of Ag is approximately 1/50 of Pt, offering significant cost advantages for fuel cell commercialization. Atomic layer deposition (ALD) has garnered substantial attention as a valuable technique for crafting high-performance nano-catalysts. ALD's self-limiting nature, based on the sequential exposure of vaporized precursors and reactants, enables precise control over catalyst size and composition. In this study, we employed plasma-enhanced ALD (PEALD) to fabricate cutting-edge AEMFC cathodes comprised of carbon nanotubes (CNTs) adorned with Ag. This approach yielded impressive results, achieving an AEMFC output exceeding 300 mW cm-2 or more than 2 W mgAg
-1 at 65 °C with a CNT cathode featuring an exceedingly low Ag loading of less than 0.15 mg cm-2. Notably, this represents the world's highest reported Ag-AEMFC performance to date. The Ag-decorated cathode created through ALD played a pivotal role in significantly reducing resistance in the polarization region, a major contributor to overall energy losses in AEMFCs. Additionally, when evaluating the durability of the Ag-decorated CNT anode in an alkaline environment, we observed excellent long-term stability. In this presentation, we will discuss a more detailed exploration of the relationship between AEMFC performance, featuring ALD-fabricated Ag-CNT catalysts, and the intricate catalyst structure.
Advancements in Electrocatalysts for Low-Temperature CO2 Electrolysis: Progress and Insights from the ECO2Fuel Project
Authors: Huq Faria
Published: August 2024

The Electrochemical CO2 Reduction Reaction (CO2RR) represents a cutting-edge approach for converting CO2 into valuable chemicals and fuels, marking a significant stride in energy storage through chemical bonds. This innovative method ingeniously merges the well-established water splitting reaction with Fischer-Tropsch synthesis, traditionally dependent on high temperatures and pressures. However, uniquely, CO2RR facilitates this process under ambient conditions, combining hydrogenation with water splitting at room temperature and normal atmospheric pressure. In this context, the ECO2Fuel project, an initiative under the European Green Deal, aims to develop, implement, and validate the first-ever 1MW low-temperature direct electrochemical CO2 conversion system, poised to produce economically viable and sustainable e-fuels and chemicals.

Despite its transformative potential, the ECO2Fuel project acknowledges and addresses several pivotal challenges, including enhancing catalyst performance and selectivity, electrode longevity, mass transport optimization, averting electrolyte flooding, and mitigating the hydrogen evolution reaction.

This presentation will predominantly concentrate on refining the gas diffusion electrode at the cathode, for large-scale fuel and alcohol production via CO2RR. This electrode is composed of a gas diffusion layer, ensuring efficient CO2 transport; a catalyst layer where the reduction transpires; and a top adhesion layer to prevent catalyst delamination. These components collectively influence the electrode’s selectivity, durability, and stability.

Our discourse will delve into the intricate aspects of the catalyst layer and porous transport layer design, along with electrode manufacturing techniques, demonstrating their critical roles in achieving high faradaic efficiencies for carbonaceous fuel production. Furthermore, we will explore the nuanced operational modalities of the CO2 electrolyzer cell, focusing on strategies to curtail the parasitic side reaction of hydrogen evolution, thereby enhancing the system's overall efficiency and productivity.

This project has received funding from the European Union’s Horizon 2020 research and Innovation program under grant agreement no. 202037389.
Theoretical Investigation of the Adsorbate and Potential-Induced Stability of Cu Facets during Electrochemical CO2 and CO Reduction
Authors: Varley Joel , Yu Henry , Govindarajan Nitish , Weitzner Stephen Eric , Akhade Sneha A
Published: August 2024

The activity and product selectivity of electrocatalysts for reactions like the carbon dioxide and carbon monoxide reduction reactions (CO2RR and CORR) are intimately dependent on the catalyst’s structure and composition. While engineering catalytic surfaces can improve performance, discovering the key sets of rational design principles remains challenging due to limitations in modeling catalyst stability under operating conditions. Herein, we perform first-principles density functional calculations adopting implicit solvation methods with potential control to study the influence of adsorbates and applied potential on the stability of different facets of model Cu electrocatalysts. Using coverage dependencies extracted from microkinetic models, we describe an approach for calculating potential and adsorbate-dependent contributions to surface energies under reaction conditions, where Wulff constructions are used to understand the morphological evolution of Cu electrocatalysts under CO2RR and CORR conditions. We identify that CO*, a key reaction intermediate, exhibits higher kinetically and thermodynamically accessible coverages on (100) relative to (111) facets, which can translate into an increased relative stabilization of the (100) facet during CO2RR. Our results support the known tendency for increased (111) faceting of Cu nanoparticles under more reducing conditions and that the relative increase in (100) faceting observed under CO2RR conditions is likely attributed to differences in CO* coverage between these facets.

This work was partially performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and partially supported by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Advanced Materials & Manufacturing Office.
(Invited) Dynamic Operation of Solid Oxide Electrolyzers
Authors: Tucker Mike C , Zhu Zhikuan
Published: August 2024

Electrolysis of steam to generate hydrogen is expected to be a highly dynamic operation if renewable resources such as wind and solar are used as the electrical power input. Rapid fluctuation of input power and intermittent operation of the solid oxide electrolysis stack will result in transient operating conditions at the cell level. All operating variables such as temperature, steam content, voltage, flow rate, etc. may change rapidly in these conditions.

To address this situation, this work operates Ni/YSZ-supported and metal-supported cells under highly dynamic conditions, with individual variables isolated. The cells are remarkably robust to dynamic operation. A safe range is found for each operating variable, with accelerated degradation observed outside that range in certain cases. For example, cycling Ni/YSZ-supported cells between 1.3 V and 1.6V at 750°C and 50:50 H2O:H2 is tolerated well, but increasing the upper voltage to 1.7 V and higher leads to increased degradation. Additionally, Steam:hydrogen ratio is cycled between 3:97 and 75:25. Temperature is cycled between 150 and 800°C. Operation is cycled between fuel cell and electrolysis modes, with synchronized steam content. Metal-supported cells tolerate steam cycling, voltage cycling, temperature cycling and redox cycling, and results for button cells and 50 cm2 planar cells will be reported. In many cases, hold times are 1 minute, allowing thousands of cycles to be accumulated over hundreds of hours of operation.

Figure 1. Dynamic cycling of a Ni/YSZ-supported button cell at 750C. (Top) Cycling between 1.3 and 1.7V with 1 min holds and 50/50 H2/H2O. (Bottom) Cycling between various steam contents at 1.3 V.

Figure 1
A Direct Dry Synthesis Route for High Purity Catalytic Nanoporous Metallic Films
Authors: Barad Hannah , Kwon Hyunah , Silva Olaya Alex Ricardo , Alárcon-Correa Mariana , Wittstock Gunther , Fischer Peer , Bartl Johannes D.
Published: August 2024

Control of catalyst morphology is important because it affects many catalytic related properties such as, active sites, surface energy, and surface area, which can lead to tunable catalytic activity. Nanoporous metallic networks (NPMs), a morphology of interest for catalysis, contain many uncoordinated atoms at the surface and highly curved ligaments that can have a large effect on catalytic performance. Nanoporous self-supported metal structures have been synthesized in the past by dealloying of a master alloy,[1] which is a wet chemical method. This technique uses an Au-Ag alloy, from which Ag is etched away and which always results in NPMs containing residual amounts of the sacrificial metal (Ag) preventing the formation of high-purity structures. It follows that the catalytic properties of pure NPMs formed by dealloying can not be studied due to metal 'impurities' remaining in the structure. Although these 'impurities' contribute to catalytic activity and stability, it is difficult to control their amount and the systematic investigation of the 'impurity' effect is almost impossible for these NPMs.

Here, we present results obtained by using physical vapor deposition, in the form of glancing angle deposition (GLAD), together with plasma etching to form nanoporous ultra-thin metal mesh structures, in a unique and facile dry synthesis method,[2] unlike most wet chemical synthesis methods used to prepare catalysts, which result chemical waste. The nanostructured metal mesh films are suitable for catalysis as they are extremely pure and highly porous, and contain high curvature ligaments, different crystal motifs, and many grain boundaries. We present nanoporous gold films (NPGF) prepared by our method as an example material. We show that the electrochemical structural stability of the NPGF is remarkably higher than that of dealloyed nanoporous gold, which is a result of the high amount of grain boundaries. Furthermore, the electrocatalytic performance of CH3OH oxidation is measured and the results show high catalytic activity for pure NPGF.[3] Our GLAD method can be applied to various metals and enables precise mixing or doping of different materials composing the NPMs. The high porosity, active sites, and potential elemental mixing will lead to new catalysts, especially suitable for CO2 reduction to fuels and value-added chemicals.

[1] G. Wittstock, M. Bäumer, W. Dononelli, T. Klüner, L. Lührs, C. Mahr, L. V. Moskaleva, M. Oezaslan, T. Risse, A. Rosenauer, A. Staubitz, J. Weissmüller, A. Wittstock, Chem. Rev.
2023, 123, 6716.

[2] H. Kwon, H.-N. Barad, A. R. Silva Olaya, M. Alarcón-Correa, K. Hahn, G. Richter, G. Wittstock, P. Fischer, ACS Appl. Mater. Interfaces
2023, 15, 5620.

[3] H. Kwon, H.-N. Barad, A. R. Silva Olaya, M. Alarcón-Correa, K. Hahn, G. Richter, G. Wittstock, P. Fischer, ACS Catal.
2023, 11656.
Quantitative Study of Dislocation Density Effects on (100)-Orientated Cu in CO2RR
Authors: Zhang Caiwei , Wong Andrew Barnabas
Published: August 2024

For the electrochemical CO2 reduction reaction, (CO2RR) structural defects have been reported to create key active sites. Previous reports have demonstrated the relationship between structural defects and CO2RR activities. However, an in-depth understanding of the connection between defect structure and selectivity study has proved challenging.
In this presentation, we elucidate the relationship between dislocation density, activity, and selectivity on Cu in CO2RR.
To accomplish this, we successfully synthesized (100)-oriented Cu samples with dislocation densities varying by a factor of 9, and we quantitatively studied the relationship between dislocation density and CO2RR performance.

In this work, we employ (100)-oriented Cu prepared by physical vapor deposition. This approach creates an atomically smooth surface that eliminates the differences in the relative influence based on differences in surface reconstruction and roughness factor. A suite of X-ray-based methods are applied to characterize the defect structure. Here, X-ray diffraction pole figures confirm the good epitaxial growth of Cu (100). X-ray diffraction (XRD) θ/2θ symmetrical scan are applied to facilitate calculation of the dislocation density. Unlike TEM and metallographic etching, this method provides precise structure information over large areas of the Cu catalyst.

It is demonstrated that under the potential of -1.04 V vs. RHE, the sample with the largest dislocation density favors HER more. With high dislocation density, HER and C1 products are dominant. The situation changes with the dropping dislocation density, and the best CO2RR performance is achieved at a medium dislocation density changing from 1.668 x 1015 m-2 to 1.106 x 1015 m-2, indicating a favorable catalyst surface for C-C coupled products. Here, a combination of mechanistic study via electrochemical methods and X-ray absorption spectroscopy suggests that a combination of low- and full-coordinated Cu sites is more beneficial for C-C coupling.

Figure 1
(Invited) Efficient Recycling of Dilute Nitrate to Ammonia Using Cu-Based Electrocatalyst
Authors: Feng Xiaofeng
Published: August 2024

The use of nitrogen fertilizers has contributed significantly to the growth of agricultural production, but the nitrogen use efficiency is typically lower than 40%, so most of the nitrogen readily leaches into ground water, rivers, and lakes, causing an increase of nitrate (NO3
−) concentration and severe environmental problems. Electrochemical reduction of nitrate has emerged as a promising route for the recycling of nitrate from wastewater and sustainable production of ammonia when powered by renewable electricity. Here I present our recent studies of the intrinsic activity and selectivity of Cu for nitrate electroreduction, as well as a rational design of Cu-based catalysts for single-pass conversion of nitrate to ammonia. Using polycrystalline Cu foils for benchmarking, we elucidated the impact of often overlooked factors on nitrate reduction, including Cu facet exposure, nitrate concentration, and electrode surface area. We find that an electropolished Cu foil exhibits a higher activity and selectivity for nitrate reduction to ammonia than a wet-etched Cu foil, benefiting from a greater exposure of Cu(100) facets that are more favorable for the reaction. The NH3 selectivity shows no apparent dependence on the nitrate concentration, but it increases monotonically with Cu electrode area, which is attributed to a promoted conversion of intermediately produced NO2
− to NH3 on a larger electrode. Based on the understandings, we further developed a Cu/Co-based tandem electrocatalyst, which achieved nearly 100% single-pass conversion of dilute nitrate (5−50 mM) to NH3 at a low overpotential using a flow cell.
Electrochemistry of Diquinonyl Amines with an Internal Proton Source
Authors: Becker James Y.
Published: August 2024

It is well established that quinones play an important role in various biological systems. Studying electrochemical properties of quinones affords fundamental knowledge of semi-quinone radicals formation in vivo and in vitro in different media.

Following our previous work on electrochemical properties of various quinonyl amines [1], Scheme 1 below describes seven diquinonyl amines. Noteworthy that six of them (1-6) contain an internal proton donor (‘NH’) except for the seventh one (7), in which both quinone moieties are attached to ‘NMe’ group. Their redox potentials were measured by cyclic voltammetry in dichloromethane [2].

The results show a strong dependence of the nature of substituent on the first reduction potentials, and that protonation of diquinonyl amines is feasible by internal proton source even in a non-polar medium.

References

[1] S. Bittner, S. Gorohovsky, O. Paz-Tal (Levi), J.Y. Becker, Amino Acids, 2002, 22,

71-93

[2] G. Temtsin-Krayz, S. Bittner, A. Dhiman and J.Y. Becker, "Electrochemistry of

Quinones with Respect to their Role in Biomedical Chemistry", Chem. Rec.,
2021, 21.

Figure 1
Electrochemical Hydrogenation in Action: Redefining the Production of Commodity and Fine Chemicals
Authors: Pellumbi Kevinjeorjios , Kleinhaus Julian Tobias , Wickert Leon , Wolf Jonas , junge Puring Kai , Apfel Ulf-Peter , Siegmund Daniel
Published: August 2024

Electrocatalytic hydrogenation reactions (ECH) are increasingly recognized as promising approaches for the reductive production of both commodity and fine chemicals. Particularly when powered by renewable energies, ECH offers a sustainable alternative, avoiding the need for gaseous hydrogen, high-pressure conditions, and stoichiometric reducing agents, which often lead to excessive waste formation. Moreover, ECH processes can be conducted under mild conditions near room temperature, utilizing environmentally friendly solvents like water as a proton source. This marks them as a sustainable process for the future.1 Here, we discuss our latest advancements and challenges in advancing electrochemical hydrogenations towards significant industrial applications. We focus on critical aspects such as catalyst selection, electrode design, and the suitability of reactor concepts, illustrated through selected unsaturated organic substrates that are used industrially on a large scale. Specifically, we explore the selective semi-hydrogenation of internal and terminal alkynes as well as (di)aldehydes. Each substrate presents unique challenges and opportunities, showcasing potential pitfalls, unexpected reaction pathways, and serving as a source of inspiration for future ventures in electroorganic synthesis.1-3

References:

1) J. T. Kleinhaus, J. Wolf, K. Pellumbi, L. Wickert, S. C. Viswanathan, K. junge Puring, D. Siegmund*, U.-P. Apfel*, Chem. Soc. Rev.
2023, 52, 7305.

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(Invited) Introducing Selectivity into Electrochemical Reactions: From Solution to Surfaces
Authors: Karr Dylan
Published: August 2024

Induction of asymmetry into electrosynthetic reactions has taken off in recent years for the electrochemical community. As of late most transformations have focused on either simple electrochemical oxidations or reductions, such as the reduction of various ketones to chiral alcohol feedstock molecules, or transition metal cross coupling reactions. At the same time, there has been little effort to introduce asymmetry into cyclization reactions that capitalize on highly reactive radical ion intermediates to accomplish umpolung-type transformations or to fully take advantage of electrode surfaces for manipulating the selectivity of synthetically more complex transformations like transition metal cross coupling reactions. In the case more complex electrochemical transformations, many of the reactions studied have led to either high ee and low yield or low ee and high yield. With this in mind, we are looking new approaches for introducing selectivity into electrochemical transformations by taking advantage of high yielding cathodic cyclization reactions and the Heck reaction. The influence of chiral electrolytes, chiral catalysts and mediators, and modified electrode surfaces on these transformations is being explored with a particular emphasis on both the induction of asymmetry into the reactions and the use of remote functionality in the molecules as a control element. This presentation to be given will detail our progress in these areas.
Electrochemical Detection of Tobramycin Retention in E. coli Bacteria
Authors: Wiebe Kolby , Kuss Sabine , Lopes Luma Clarindo , Jiang Angela , Zarychta Michael , Ramirez Danyel , Schweizer Frank
Published: August 2024

Escherichia coli are Gram-negative bacteria that are commonly found in the intestines of many different animals, including humans. E. coli can cause severe infections to humans if a foreign strain is ingested. Antibiotic resistance is a global problem for treating E. coli infections.1 A common class of drugs for treating Gram-negative infections are aminoglycosides, such as tobramycin (TOB). The presented work focuses on the quantification of cellular drug uptake to draw conclusions about the resistance phenotype in bacteria. This procedure is applicable to pathogens that are tobramycin-resistant either because of drug efflux or because they exhibit reduced membrane permeability. TOB is an electroactive molecule which is quantitatively detected directly using electroanalytical chemistry. Herein, both susceptible and resistant strains of E. coli were exposed to TOB and their ability to retain the drug is quantified using differential pulse voltammetry. The presented method successfully determines drug resistance in E. coli using electrochemistry.

References:

Poirel, L. et al. Antimicrobial Resistance in Escherichia coli. Microbiology Spectrum
6, (2018).
Electrically Conductive Peptide Fibers as Direct Electron Transfer Scaffolds for Enzymatic Electrocatalysis
Authors: Grosvirt-Dramen Adam , Urbach Zachary , Wang Fengbin , Hochbaum Allon
Published: August 2024

Biology provides many sources of inspiration for synthetic and multi-functional nanomaterials. Naturally evolved proteins possess a range of unique functions and self-assembly behavior. Some of these have electron transport functions as part of metabolic processes. Their flexible design and potential for stimuli responsiveness make proteins ideal building blocks of bioelectronic interfaces. In biosensor and electrocatalysis applications, bioelectronic materials are designed to interconvert biological signals or processes into electronic signals and vice versa. In this work, we designed a peptide fiber structure that exhibits stimuli-responsive self-assembly and the capacity to transport electrical current over micrometer long distances. Hierarchically ordered nanofibers of α-helical coiled-coil peptides were assembled using a pH responsive structure ordering motif comprising of two neighboring lysine residues. Cryo-EM structures of these assemblies reveal a novel organization of α-helical peptides in a cross coiled coil arrangement that exhibits electrical conductivity. Both solid-state and solution-based electrochemical characterization show that these fibers are conductive. Single-fiber conductive AFM determined that the solid-state electrical conductivity is on a similar order of magnitude with conductive cytochrome filaments from bacteria. Solution deposited fiber films approximately doubled the electroactive surface area of the electrode, confirming their conductivity in aqueous environments. Furthermore, these fibers can be used as scaffolds for redox enzyme immobilization for electrochemical biosensing. Progress towards immobilized enzymatic devices will be discussed as well. This work further expands the field of stimuli-responsive and multifunctional nanomaterials by using peptide assemblies as structural supports for future implementation in bioelectronic and bioelectrochemical systems.
Unusual Long-Term Stability of Enzymatic Bioelectrocatalysis in Organic Solvents
Authors: Bichon Sabrina , Staigre Priscilla , Gounel Sébastien , Safarik Tatjana , Carucci Cristina , Kuhn Alexander , Mano Nicolas
Published: August 2024

Organic solvent tolerant enzymes are of tremendous importance for the pharmaceutical industry in search of high added-value chemicals. However, enzymes exhibit usually weak long-term activity and stability in various media. Here, we report a general strategy allowing stabilizing and keeping enzymes active in biphasic systems upon immobilization on an electrode surface. It consists in the combination of an engineered solvent-tolerant enzyme, combined with fine-tuned osmium-based redox polymers where the concentration of osmium complex has been specifically tuned to minimize its deswelling associated with the use of porous gold electrodes. This approach is validated with bilirubin oxidase as a model system. This copper enzyme is able to oxidize a wide range of substrates, combined with the reduction of O2 to water. While all other enzymatic systems irreversibly lose their activity and stability in the presence of 7.5 M methanol or below, this optimized enzymatic system stays functional in 12.5 M methanol with no loss in current density. It exhibits a half-life of more than 8 days, which is unprecedented in the literature. We show that this electrode can also operate in DMSO, dioxane, acetonitrile and acetone, thus opening up a very wide variety of applications in the field of bioelectrocatalysis and bioelectrosynthesis.

Figure: Example of a long-term stability experiment for a mediated bilirubin oxidase biocathode in 12.5 M methanol. Black curve: immobilized on a bare gold electrode; red curve: immobilized on a 11/2 layers porous gold electrode. Experiments performed at +0.1V vs. Ag/AgCl. The total loading was fixed at 600 µg.cm-2 for both experiments.

Figure 1
(Digital Presentation) Synergistic Integration of Chitosan Nanoparticles and Electrochemical Methods: Advancing Reducing or Oxidizing Metabolism in Pickering Emulsion Systems
Authors: Bhutto Rizwan Ahmed
Published: August 2024

This abstract explores the promising integration of chitosan nanoparticles, synthesized by microorganisms or enzymes, with electrochemical methods to enhance reducing or oxidizing metabolism, particularly within Pickering emulsion systems. Chitosan, known for its biocompatibility and biodegradability, can be tailored through enzymatic or microbial synthesis to yield nanoparticles with customizable characteristics. When incorporated into Pickering emulsions, these nanoparticles act as stabilizers, offering improved stability and control over droplet size distribution. Electrodeposition assembly, allows precise manipulation of chitosan molecules into chitosan nanoparticle properties, enhancing their adsorption at the oil-water interface (950 contact angle) and thus improving emulsion stability for 90 days. Additionally, the electrochemical environment can facilitate redox reactions involved in metabolic processes, thereby promoting enzymatic activity or microbial growth. This integrated approach not only enhances Pickering emulsion efficiency but also holds promise for applications in biocatalysts, drug delivery, and environmental remediation, where controlled metabolism is crucial. Through innovative strategies leveraging the synergies between chitosan nanoparticles, microorganisms, or enzymes, and, researchers are advancing toward sustainable and efficient solutions for diverse biotechnological challenges.
Exploration of a Reliable and Robust Reference Electrode for Point-of-Care Diagnostic Devices
Authors: Glasco Dalton Lee , Bell Jeffrey Gordon
Published: August 2024

Electrochemical sensing for point-of-care (POC) diagnostics has emerged as a heavily studied field. Many groups have developed novel sensors and devices utilizing low-cost materials, highly selective recognition elements, and rapid responses which detect a vast number of biomarkers and pharmaceuticals. The sensor(s) of a POC device is the priority for selectively sensing a particular molecule/ion, but all electrochemical cells require additional electrodes (e.g., counter and reference) for performing measurements. In regard to a counter electrode many low-cost alternatives have been utilized, but a reliable and robust reference electrode has been the primary challenge for many diagnostic devices. In a laboratory setting, commercial references electrodes are heavily used for electrochemical analysis, but at the POC, commercial reference electrodes are not suitable since they are bulky, expensive, and require continual maintenance. In this presentation an alternative to commercial reference electrodes is studied. The fabrication and optimization of a 3D printed reference membrane was explored. A variety of compositions were tested for the development of a robust and reliable reference electrode that could be into a POC device coupled with a 3D printed sensor.
Cu-Containing Metal-Organic Framework Electrocatalyst for Efficient Production of C2+ Compounds via CO2 Reduction Reaction
Authors: Jang Juhee , Shao Minhua
Published: August 2024

The electrochemical reduction of CO2 (CO2RR) is a promising strategy to yield valuable carbon-containing products and mitigate current environmental and energy issues. Cu-based MOF electrocatalysts have great potential for the selectivity of C2+ products due to their unique property. However, the rational design of active sites in Cu-based MOFs needs to be further studied. In this work, we propose a strategy to evolve abundant partially oxidized Cu species by applying a negative potential prior to CO2RR on Cu-MOFs, which results in high faradaic efficiency of 78% and partial current density of −46 mA cm−2 at −0.95 VRHE towards multi-carbon products. The electrochemical activation of Cu-MOFs can lead to the shift of superficial chemical state from Cu2+ to Cu+. Interestingly, the conversion rate is varied by different thermal annealing times on the pre-catalysts. Thereby, the relative concentration of Cu+ species can be quantitatively compared before and after activation to reveal the dependence on those FEC2+. The insights gained from this study can provide valuable guidance for the design and development of efficient Cu-MOF catalysts for the production of C2+ products.