bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating (photo)-Electrochemical Pathways for the Remediation of Co-EDTA Wastewater Streams
Authors: Wu Jhen-Cih , Su Xiao , Hou Chia-Hung
Published: December 2024

The discharge of heavy metals into water bodies has dramatically increased due to the rapid expansion of industrial and human activities, posing severe threats to ecosystems and human health. This pressing issue is exacerbated by the presence of chelators like EDTA and its heavy metal complexes (HMCs), which hinder the effectiveness of conventional water treatment methods. These chelated heavy metals possess stable structures and high environmental mobility, making the remediation of heavy-metal-contaminated wastewater streams significantly challenging. In recent years, cobalt has become increasingly favored for interconnects and contacts in semiconductor manufacturing due to its lower resistivity and superior resistance to electromigration compared to copper. This shift has led to a noticeable accumulation of cobalt-EDTA (Co-EDTA) in waste streams, particularly from chemical mechanical polishing (CMP) processes. Despite systematic investigations into the decomplexation of copper-EDTA (Cu-EDTA) and nickel-EDTA (Ni-EDTA), research focusing on Co-EDTA removal and its destruction pathways using (Photo)-EAOPs remains lacking.

This study aims to explore the (photo)-electrochemical performance of a tailored TiO2-encapsulated electrified membrane for Co-EDTA remediation. Under both electrocatalysis (EC) and photo-electrocatalysis (PEC) conditions, the electrified membrane exhibited significant efficacy in degrading EDTA-Na2, highlighting its potential in chelator decomposition. The addition of UV-LED light further enhanced the kinetics of EDTA-Na2 removal. Cobalt complex decomposition rates reached approximately 45-50%, with PEC demonstrating superior efficiency. Furthermore, varying cathode voltages revealed notable impacts on Co-EDTA decomplexation and cobalt recovery. The experimental findings also emphasized the role of electrolyte concentration in optimizing total cobalt and total organic carbon (TOC) removal rates. To validate the practical application of the system, we simulated a municipal wastewater treatment scenario spiked with 0.5 mM Co-EDTA, demonstrating the feasibility of the electrified membrane system. This research showcases the potential of (Photo)-EAOPs in effectively mitigating heavy metal complex contamination in real-world wastewater treatment settings.
Fabrication of Uniform Porous Anodic Aluminum Oxide by Anodizing Aluminum in Trisodium Phosphate with Higher pH Values
Authors: Hsieh Hsuan-Lin , Terashima Ayasa , Kikuchi Tatsuya
Published: December 2024

Anodizing of aluminum is an electrochemical process of surface oxidation to form an alumina layer. Porous anodic aluminum oxide (PAAO) possessing self-organized nanopores can be obtained by anodizing aluminum in several acidic electrolyte solutions, and it has been widely used to develop emerging applications, such as nano-filters and optical devices. Recently, we found that anodizing in several alkaline solutions caused the formation of PAAOs with unique nanostructures such as an extremely high porosity and ultra-flat barrier layer. However, the anodizing process in alkaline solutions with higher pH values produced a slightly non-uniform film due to the active dissolution environment of alumina. Herein, we report the fabrication of uniform PAAO film by anodizing aluminum in alkaline solutions and their unique nanostructures.

High-purity aluminum specimens were electropolished in 78 vol% CH3COOH/ 22 vol% - 70% HClO4. The electropolished specimens, then, were anodized in a 0.3 M trisodium phosphate (Na3PO4) solution at 274 K (pH = 13.1) and a constant voltage of 2-100 V. A platinum plate was used as the cathode, and the aluminum specimen was placed parallel to and 22 mm from the platinum plate. We investigated the effect of various operating conditions on the formation of PAAO film. The growth behavior and internal structure of anodized specimens were examined by optical microscopy (OM), field-emission scanning electron microscopy (FE-SEM), and scanning transmission electron microscopy (STEM).

Figure 1a shows the OM images of the aluminum specimen anodized in a 0.3 M Na3PO4 solution at 274 K and a constant voltage of 20 V for 60 min with and without stirring the solution. A non-uniform appearance with both weak white and metallic luster areas was obtained on the specimen anodized with stirring, whereas a uniform metallic luster can be observed without stirring. The SEM images of four different surface positions (2 mm intervals) of each anodized specimen are shown in Figure 1b. In the case of the stirring condition, the surface of PAAO on the left was dissolved due to the high pH value of the Na3PO4 solution and higher dissolution rate caused by stirring. On the other hand, a uniform PAAO film possessing similar nanoscale pores was successfully fabricated by suppressing non-uniform dissolution without stirring. The PAAO film grew by anodizing in the Na3PO4 solution at extremely low applied voltages less than 10 V.

Figure 1
Electropolishing of Magnesium and Its Alloys in Highly Safe Sodium Chloride/Glycol Solutions
Authors: Tomita Shunsuke , Kikuchi Tatsuya
Published: December 2024

Magnesium and its alloys are expected to be used in various engineering fields, such as automobiles, trains, and electronic product enclosures due to their lightness and mechanical properties. Electropolishing of magnesium surfaces is an important technique for fundamental research works and industrial applications, and perchloric acid or nitric acid is typically used for electropolishing. However, these acids are highly reactive and hazardous, thus the usage should be avoided in the industrial application processes. In this study, we demonstrated a highly safe electropolishing process of magnesium using a novel sodium chloride/glycol solution.

High-purity magnesium plates (99.95 wt%, 1 mm thick) were used as the starting materials. The specimens were ultrasonically degreased in ethanol for 10 min. The magnesium specimen as the anode and a platinum plate as the cathode were immersed in four types of glycol solutions including 0.5 M NaCl/ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TrEG), and tetraethylene glycol (TeEG) solutions at 278-308 K, and linear sweep voltammetry (0.1 Vs-1) and constant voltage electrolysis (25-100 V) were carried out. After electrolysis, the surface of the specimens was examined by stereo microscopy (SM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The regular reflectance from the magnesium surfaces was measured using a spectrophotometer. Two types of industrial magnesium alloys including Mg-Al alloy, AZ31, and Mg-Li alloy, LZ91, were also used for electrolysis.

As the voltage-current curves were measured by linear sweep voltammetry of the pure magnesium specimen in four types of glycol solutions, clear diffusion limiting currents were obtained after the initial current increases. We found that the unevenness of the magnesium specimens decreased by constant voltage electrolysis at appropriate applied voltages in NaCl/DEG and NaCl/TeEG solutions. Figure 1a shows the surface appearances of pure magnesium, LZ91, and AZ31 after constant voltage electrolysis at 50 V in NaCl/DEG solution for 60 min. The pure magnesium specimen and LZ91 alloy were successfully electropolished by constant voltage electrolysis and mirror-finished surfaces were obtained. On the other hand, the AZ31 alloy exhibited a nonuniform appearance with the coexisting of metallic luster and brownish regions, although a mirror-finished surface was obtained. The difference of the electropolishing behaviors between LZ91 and AZ31 alloys may be due to the metallographic structure such as the solid solution and intermetallic compound. Three-dimensional magnesium specimens possessing the curved and spiral structures could also be electropolished by constant voltage electrolysis in NaCl/DEG (Fig. 1b).

Figure 1
Electrochemical Oxidation of Biomass-Derived Wastewaters for Simultaneous H2 Production
Authors: Boruah Bhanupriya , Bhatwadekar Swanand Sadashiv , Riedel Nickolas W , Strange Lyndi E. , Lopez-Ruiz Juan A.
Published: December 2024

As the world continues to search for new ways to support the growth of a sustainable energy future, biomass conversion emerges as a potential method to produce carbon-neutral biofuels and biochemicals. For example, hydrothermal liquefaction (HTL) can be used to convert biomass- and waste-derived feedstocks into bio-crudes, which then undergo catalytic upgrading with exogenous molecular hydrogen (H2) for biofuel production (gasoline, diesel, jet oil.). HTL also generates an aqueous phase (HTL-AP) that contains up to 5 wt.% of organic compounds that cannot be treated with traditional wastewater treatment technologies (e.g., anaerobic digestion). Instead, we propose to use the HTL-AP to in situ generate the H2 needed for biofuel production via the electrochemical oxidation (ECO) of HTL-AP.1
2

In this work, we evaluate how the HTL-AP composition of both organic and inorganic compounds as well as the applied potential affect the ECO activity, energy consumption, and electrode stability. Initially, our electrochemical experiments were performed in batch cells to understand the performance of anode and cathode for ECO and H2 generation in terms of onset potential, exchange current densities, and Tafel slopes. This was followed by a demonstration of ECO long-term stability in a continuous-flow electrolyzer. Our studies show that the presence of organic compounds decreases the current density at high potential region but increases at low potential region for some HTL-AP. The anode stability increased from 24 h to >3,000 h by optimizing the applied potential and the source of HTL-AP. However, the cathode performance and stability remained unaffected by the HTL-AP and potential. The resulting energy requirement for COD removal (kWh/kgCOD) of the optimized system is lower than that of the traditional wastewater treatment process. Furthermore, the energy requirement for H2 production (kWh/kgH2) is found to be almost half compared to the commercial electrolyzer.

References

(1) Andrews, E.; Lopez-Ruiz, J. A.; Egbert, J. D.; Koh, K.; Sanyal, U.; Song, M.; Li, D.; Karkamkar, A. J.; Derewinski, M. A.; Holladay, J. Performance of base and noble metals for electrocatalytic hydrogenation of bio-oil-derived oxygenated compounds. ACS sustainable chemistry & engineering
2020, 8 (11), 4407-4418.

(2) Qiu, Y.; Lopez-Ruiz, J. A.; Zhu, G.; Engelhard, M. H.; Gutiérrez, O. Y.; Holladay, J. D. Electrocatalytic decarboxylation of carboxylic acids over RuO2 and Pt nanoparticles. Applied Catalysis B: Environmental
2022, 305, 121060.

Figure 1
Quantifying Aging-Induced Irreversible Volume Change of Porous Electrodes
Authors: Garrick Taylor R. , Miao Yong , Macciomei Eric , Fernandez Miguel , Weidner John W.
Published: December 2024

Automotive manufacturers are working to improve cell and pack design by increasing their performance, durability, and range. One of the critical factors to consider as the industry moves towards materials with higher energy density is the ability to consider the irreversible volume change characteristic of the accelerated SEI layer growth tied to the large volume change and particle cracking typically associated with active material strain. Here, we add to a previously developed mechano-electrochemical model[1-8] to more practically understand the impact of irreversible volume change, primarily assigned to SEI layer growth. As the time from initial design to manufacture of electric vehicle is decreased in order to rapidly respond to consumer demands and widespread adoption of electric vehicles, the ability to link aging and volume change to end of life vehicle requirements using virtual tools is critical.[9] In this study[10], we apply a model to determine the irreversible volume change at the electrode and cell level, allowing for virtual design iterations to predict the volume change at battery cell aged states, and probe possible changes in the SEI layer over life.

References:

T. R. Garrick, K. Kanneganti, X. Huang and J. W. Weidner, J Electrochem Soc, 161, E3297 (2014).

T. R. Garrick, Y. Dai, K. Higa, V. Srinivasan and J. W. Weidner, ECS Transactions, 72, 11 (2016).

T. R. Garrick, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3552 (2017).

T. R. Garrick, K. Higa, S.-L. Wu, Y. Dai, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3592 (2017).

D. J. Pereira, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 166, A1251 (2019).

D. J. Pereira, M. A. Fernandez, K. C. Streng, X. X. Hou, X. Gao, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 167, 080515 (2020).

D. J. Pereira, A. M. Aleman, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 169, 020577 (2022).

T. R. Garrick, M. A. Fernandez, M. Verbrugge, C. Labaza, R. Mollah, B. J. Koch, M. Jones, J. Gao, X. Gao and N. Irish, J. Electrochem. Soc., 170060548 (2023)

T. R. Garrick, Y. Zeng, J. B. Siegel, and V. R. Subramanian, J. Electrochem. Soc., 170113502 (2023)

T. R. Garrick, Y. Miao, E. Macciomei, M. Fernandez and J. W. Weidner, J Electrochem Soc, 170, 100513 (2023).
(Invited) Elucidating Redox Mechanisms in Battery Materials through Resonant Inelastic X-Ray Spectroscopy (RIXS)
Authors: Radin Max , Kunitsa Alexander
Published: December 2024

Novel battery materials offer the promise of greatly increased energy densities for automative and other applications. However, their practical adoption is often limited by problems in electrochemical performance, such as poor rate capability, voltaic efficiency, and cyclability. Resonant Inelastic X-ray Spectroscopy (RIXS) has become a valuable tool for understanding the redox mechanisms in such materials, representing a first step towards solving problems in electrochemical performance. In many cases, however, the underlying origins of RIXS features are unclear. For example, redox mechanisms in Li-rich cathodes are associated with several absorption and emission features in oxygen RIXS measurements, but a clear picture of what redox mechanisms create these features remains elusive.

As a step towards identifying redox mechanisms in Li-rich and related cathode materials, this presentation reviews existing theories of reaction mechanisms in these compounds, revisits experimental RIXS data on these materials and related oxides, and presents ab initio calculations evaluating possible origins of commonly observed features. Results suggest that some features could arise from molecular oxygen residing in low-symmetry environments. Additionally, prospects for using error-corrected quantum computation to more accurately model such electronic structure problems will be discussed.
Leveraging Molecular Dynamics to Improve Porous Electrode Theory Modeling Predictions of Lithium-Ion Battery Cells
Authors: Dix Sean T. , Lowe Jeffrey , Rashvand Avei Mehdi , Garrick Taylor R.
Published: December 2024

Lithium-ion battery cell modeling using physics-based approaches such as porous electrode theory is a powerful tool for battery design and performance analysis, both at the battery cell and system level1. Cell metrics such as resistance and thermal performance can be quickly calculated in a pseudo-two-dimensional (P2D) framework. For engineering of electric vehicle batteries, speed and fidelity of electrochemical models is paramount in a competitive landscape. Physics-based models allow for high fidelity but require detailed knowledge of the cell component material properties. Acquiring these material characteristics typically requires time-consuming and expensive experiments limiting the ability to quickly screen through cell designs. One approach to circumvent costly experiments is to use molecular dynamics to calculate electrolyte transport properties. We demonstrate how cell modeling using simulated transport properties enables predictions of cell level metrics, allowing for experiment-free component screening. We also show how the variation in transport property predictions from molecular dynamics affects the final cell level performance predictions2.

References

T. R. Garrick, Y. Zeng, J. B. Siegel, and V. R. Subramanian, J. Electrochem. Soc., 170, 113502 (2023).

S. T. Dix, J. S. Lowe, M. R. Avei, and T. R. Garrick, J. Electrochem. Soc., 170, 083503 (2023).
(Invited) Nonlinear Frequency Response Analysis – Basics and Application for Battery Analysis
Authors: Krewer Ulrike , Weber Andre , Ulrich Julian , Chan Hoon Seng
Published: December 2024

Nonlinear frequency response analysis (NFRA), also known as nonlinear impedance spectroscopy is the younger, less well-known sibling of impedance spectroscopy (EIS). In contrast to EIS, a large sinusoidal current or potential input is used; the output signal then contains higher harmonics, which are a nonlinear fingerprint of the electrochemical system under investigation. Why is this nonlinear response of practical relevance? Because electrochemical reactions have typically a nonlinear relation of current and potential. NFRA thus allows to discriminate between different reactions that give a similar linear response (i.e. EIS), to identify and parameterise reaction kinetics or surface/degradation changes, or to simply check if a process in EIS is nonlinear. Recent applications comprise batteries, electrosyntheses, and fuel cells. [1]

This talk thrives to make NFRA more accessible to the electrochemistry and battery community. It introduces the NFRA technique (left Fig.) and its application to Li-ion batteries [3-6]. It gives an insight how to conduct reliable measurements, and which nonlinearities can be expected from reaction and transport processes [2]. Applied to Li-ion batteries, i.a. the potential for state-of-health estimation [3], for uniquely detecting Li-Plating (right Fig) or in-depth analysis on the impact of particle size on aging [5] is demonstrated. Models are shown to aid interpreting the NFR spectra. [6]

Figure. Illustration of nonlinear frequency response analysis [2] (left) and spectra showing clear changes between plating (-10°C) vs. classical aging (25°C) [4](right).

References:

[1] Vidakovic-Koch et al., Curr. Opin. Electrochem. 30, 100851, 2021

[2] Wolff et al., Europ. Phys. J. - ST 227 (18), 2617-2640, 2019.

[3] Chan et al., J. Power Sources 542, 231814, 2022

[4] Harting, Wolff, Krewer, Electrochim. Acta 281, 378-385, 2018

[5] Chan et al., Batteries Supercap. 6(10), e202300203, 2023

[6] Wolff et al., Electrochim. Acta 260, 614-622, 2018

Figure 1
Distribution of Relaxation Times of Electrolysis Cells Using Time Domain Impedance Spectroscopy
Authors: Royer Nathanael , Le Long , Meinhardt Kerry D , Lopez-Ruiz Juan A. , Marina Olga A
Published: December 2024

Electrolysis cells are being applied to increasingly diverse applications. As these devices become more ubiquitous, the need to understand the underlying processes limiting performance or contributing to degradation becomes critical. The Distribution of Relaxation Times (DRT) has emerged as a powerful technique for resolving and identifying polarization processes without a priori characterization of the system. Existing impedance measurement techniques used are not well suited for large systems or use in the field due to hardware limitations, cost, and slow measurement speeds. In comparison, time domain impedance measurement methods are faster and easier to implement, overcoming many of the drawbacks associated with conventional measurement techniques and additionally offer direct access to the DRT without needing intermediary calculations like conventional impedance spectroscopy. In this work the impedance of both high temperature solid oxide electrolysis stacks and low temperature PEM based flow cells for wastewater treatment are measured using commercial FRA’s as well as with a custom-built time domain impedance spectrometer. Using a simple current step perturbation accomplished through the rapid removal of current the entire impedance spectrum can be measured, and the resulting DRT is compared against what is obtained from conventional techniques.
Impedance Analysis of Ultramicroelectrodes for Neural Stimulation
Authors: Biney Bernard W. , Carvalho Sophia , Eluagu Cynthia C. , Olivo Elizabeth , Dong QiWei , Wu Yupeng , Cogan Stuart , Otto Kevin John , Orazem Mark E.
Published: December 2024

Most neural stimulation techniques rely on macroelectrodes, which generate electric fields that impact neuronal groups rather than specific neurons, often resulting in unintended side effects.1,2 Ultramicroelectrodes (UMEs) offer enhanced spatial resolution, holding promise for precise targeting of specific neurons to optimize therapeutic outcomes while mitigating adverse effects. However, ultramicroelectrodes present challenges. For example, delivery of required charge may require current densities that can damage the electrode or adjacent tissue.

Impedance measurements of UMEs were conducted and analyzed to understand stimulation currents and potential damage to the electrodes and tissue. The measurement-model technique was used to identify the optimal frequency range for regression analysis, to quantify the stochastic error structure, and to identify inconsistencies with the Kramers-Kronig relations. Understanding of the error structure is vital for interpretation.3 The regressions were weighted using the inverse of the variance for the stochastic error structures, and quality of fits were determined by the weighted chi-square statistic.

Process modeling was used to understand and characterize the underlying physical and chemical processes that occur at the electrode-electrolyte interface and electrode-tissue interface during neural stimulation. Constant-phase element (CPE) parameters, Q and alpha, corresponding to the behavior of the electrode-tissue interface, were obtained from this model. In addition, parameters associated with a capacitive loop were identified. Work is in progress to identify the origin of this loop.

References

(1) Otto, K. J.; Schmidt, C. E. Neuron-Targeted Electrical Modulation. Science. March 20, 2020, pp 1303–1304. https://doi.org/10.1126/science.abb0216.

(2) Orazem, M. E.; Otto, K. J., Alexander, C. L., Electrochemistry in Action-Engineering the Neuronal Response to Electrical Microstimulation. Electrochemical Society Interface
2023, 32 (1), 40–42. https://doi.org/10.1149/2.F06231IF.

(3) Orazem, M. E.; Agarwal, P.; Jansen, A. N.; Wojcik, P. T.; Garcia-Rubio, L. H. Development of Physico-Chemical Models for Electrochemical Impedance Spectroscopy. Electrochim Acta
1993, 38 (14), 1903–1911.
Phase-Selective Synthesis of Cobalt Oxide Materials Via Electrochemical Chloride-Mediated Oxidation
Authors: Kim MinJeong , Nam Ki Min , Park Gisang , Park Joon Yong
Published: December 2024

The rapid growth of the global economy has led to an elevating human demand for energy and chemicals, which is heavily reliant on the utilization and conversion of fossil fuels. Electrochemical conversion is arising as a viable strategy for synthesizing a various high-value chemicals thanks to the mild operation conditions, adjustable selectivity, and potential for scalability in industrial settings. Chlor-alkali process can be utilized for removing microorganisms, disinfecting water, and so on. Furthermore, in an electrochemical system, the oxidation half reaction of the chloride oxidation can be coupled with a value-added reduction in half reaction, such as H2 evolution, N2 reduction, CO2 reduction, and organic reduction.

In this study, β-CoOOH and γ-CoOOH, distinct cobalt oxyhydroxides, were synthesized via a chloride-mediated electrochemical oxidation process. This method employed heterogeneous reactions, where the oxidation of metal hydroxides was facilitated by electrochemically generated oxidants—active chlorine species—directly formed on the electrode surface through the oxidation of chloride ions. Characterization through X-ray diffraction (XRD) confirmed the synthesis of these two distinct metal oxide phases, elucidating their phase purity and crystal structures. Furthermore, the adjustable surface morphology and composition of intercalated ions were observed under varying electrosynthetic conditions. This synthetic strategy can be extended to the fabrication of other metal oxides, including manganese oxides. The resulting cobalt oxyhydroxide and manganese dioxide materials display versatile properties suitable for a wide range of applications in energy, environmental, and biotechnological fields.
Structural Regulation and Advanced Transmission Electron Microscopy Characterization of the Oxygen Reduction Reaction Electrocatalysts
Authors: Gong Mingxing
Published: December 2024

Fuel cells (FCs) are regarded as the most promising green energy conversion technology in the 21st century because of their advantages. However, the industrialization process of FCs is restricted by several key problems, one of which is the cathode catalyst. The Oxygen Reduction Reaction (ORR) of FCs is a complex process involving 4 electrons, which has sluggish kinetics and high over-potential. Therefore, it is usually necessary to use a large number of precious metal platinum (Pt) catalysts to improve the reaction efficiency, but the characteristics of small reserves of Pt, high price, and easy to be poisoned and deactivated increase the operating cost of the whole system. It is imperative to develop substitutes for non-Pt-based ORR catalysts and reveal their structure-activity relationship with advanced characterization techniques.

There are two ways to solve this problem: one is to improve the utilization rate of platinum-based catalyst, the other is to develop non-platinum-based catalysts. In terms of improving the utilization rate of Pt, our research group mainly constructed new Pt-based ordered intermetallic compound catalytic materials, and improved the surface structure, alloying degree and electronic structure of Pt-based catalysts by changing the atomic types, proportions and post-treatment temperatures of Pt and transition metals, so as to regulate their electrocatalytic properties. On the other hand, the morphology control of ordered intermetallic compounds has always been a major challenge in this field, and we have made a preliminary attempt in the morphology control. At the same time, with the help of modern characterization techniques, it is of great significance to study the changes of structure and components during the service of Pd-based catalysts, and to understand their failure behavior and performance attenuation mechanism for the subsequent optimization and commercialization of Pd-based catalysts. Among them, visualization technology based on transmission electron microscopy (TEM) has become a research hotspot because it can directly observe the failure process of catalysts in service.
FCC-Based High Entropy Alloy (AlFeCoNiCu) Catalysts for Electrochemical Ammonia Production from Nitrate
Authors: Choi Jinuk , Lim Hyojung , Jeong Gyoung Hwa , Sim Uk
Published: December 2024

Ammonia (NH₃) is one of the most important materials for human activities, finding versatile applications in areas such as fertilizers, hydrogen carrier, and carbon-free energy fuel. Traditionally, NH₃ is produced through the energy-intensive Haber-Bosch (HB) process, resulting in considerable CO₂ emissions. As an alternative, electrochemical NH₃ production is gaining attentions. The electrochemical nitrate reduction reaction (NO₃RR) has been explored due to its advantages, including a low energy barrier, high nitrogen source solubility in the electrolyte, and high activity. In order to produce NH3 electrochemically, transition metal-based alloys have been employed as catalysts due to their features such as high conductivity, synergy effects, and low cost. However, transition metal catalysts suffer from low NH3 selectivity and high activity of hydrogen evolution reaction (HER), which is a competitive reaction. Recently, high-entropy alloy (HEA) catalysts have been employed as catalysts due to their features such as high entropy effect, lattice distortion, cocktail effect, and sluggish diffusion. To enhance the activity and selectivity of the NO₃RR, we developed FCC-based HEA (AlFeCoNiCu) electrocatalyst. The FCC-based HEA catalysts demonstrated a yield rate exceeding 9.88 mg h-1 cm-2 and a faradaic efficiency (FE) of 90.2 % at -0.6 V vs. RHE in 0.1 M NO₃- and 1 M KOH solution. This research is expected to contribute not only to the efficient production of ammonia under ambient conditions but also to the exploration of HEAs catalysts for enhancing the NO3RR pathway.
Influence of Process Parameters on Electrochemical CO2 Reduction to C2+ Products
Authors: Pradellok Florian , Hüwels Jan , Wessling Matthias , Keller Robert
Published: December 2024

With an increasing concentration of carbon dioxide (CO2) in the atmosphere, greenhouse gas emissions must be mitigated to prevent further global warming. A promising technology to achieve this goal is the electrochemical reduction of CO2. Thereby, CO2 is converted to value-added chemicals using renewable electrical energy. Ethylene or ethanol are valuable C2+ products, which may be synthesized with copper based catalysts. However, many studies lack control of temperature and CO2 excess factors as well as the application of industrially relevant current densities above 200 mA cm-2. Additionally, recent literature proposes benefits of pulsed operation as opposed to static operation. Pulsed operation employing gas diffusion electrodes at elevated current densities must be studied in more detail to assess the full potential of dynamic operation.

This work demonstrates the continuous electrochemical reduction of CO2 to C2+ products at industrially relevant conditions. Current densities from 100 mA cm-2 to 400 mA cm-2 are applied to an electrochemical flow cell with a geometrical electrode area of 25 cm2. CuO nanoparticles were deposited on gas diffusion layers as catalyst via automated ultrasonic spray-coating. Throughout electrolysis experiments, constant electrolyte temperatures of 20 °C or 40 °C and constant CO2 excess factors of 2 or 5 are maintained. In contrast to statically applied current, pulsed current experiments focus on enhanced CO2 mass transfer to the catalyst layer.

Throughout static electrolysis, an increase in Faradaic efficiency from 30 % to 60 % for C2+ products is observed when the current density is increased from 100 mA cm-2 to 400 mA cm-2. This is attributed to a more alkaline pH in the catalyst layer caused by high current densities which is favorable to produce C2+ products. Furthermore, it was found that an electrolyte bulk temperature of 20 °C increases the Faradaic efficiency for C2+ products compared to experiments conducted at 40 °C. We hypothesize that this is due to less intermediate desorption from the catalyst. Furthermore, the reduction of CO2 excess leads to an increase in Faradaic efficiency for C2+ products. The highest Faradaic efficiency to C2+ products was found at 400 mA cm-2 with an electrolyte bulk temperature of 20 °C at a CO2 excess factor of 2. Additionally, the influence of pulsed current on the yield of C2+ products was investigated and different pulsing procedures were tested. The results show that pulsed current operation reduces the parasitic hydrogen evolution. However, the C2+ formation was not increased compared to static operation in an electrochemical flow cell at high current densities. In summary, this work shows how different process parameters influence the product distribution in electrochemical CO2 reduction on a CuO catalyst to improve the selectivity towards C2+ products. This is a further step towards a sustainable process to produce platform chemicals.
Application of Porous Electrode for Energy Efficient Electrocoagulation
Authors: Jang Gyoung Gug , Dutta Swapnamoy , Zhang Yuxuan , Kim Kyungho , Chellam Shankararaman , Tsouris Costas
Published: December 2024

Electrocoagulation (EC) has been recognized as a promising electrochemical water treatment technology. Porous electrodes were investigated for enhanced EC removal efficiency and reduced energy consumption associated with their high surface area. In this study, we characterized EC performance in both batch and continuous flow EC reactors for treating secondary effluent wastewater. Here, we highlight the possible use of porous electrodes to revolutionize EC by enhancing pollutant removal efficiency, such as virus attenuation, while maintaining Faradaic efficiency and significantly reducing energy consumption. To gain a deeper understanding of porous electrode functionality, we conducted advanced analysis employing neutron computed tomography to characterize internal structural changes in the porous foam electrode after EC water treatment. Combining this method with microscopic analysis, we validated that the internal surface area of porous electrodes is involved in electrochemical dissolution at the anode and reductive deposition at the cathode. This technique provided valuable insights into electrochemical processes occurring within porous electrodes, shedding light onto their role in pollutant removal mechanisms. Moreover, we systematically investigated the size effect of electrode porosity in virus attenuation, energy requirements, Faradaic efficiency, and the efficiency of removing pollutants such as silica and hardness to determine the optimal porosity for high EC performance. Through comprehensive studies of continuous flow EC reactor systems, we will discuss the scalability and practicality of porous electrode-based EC systems for real-world applications. This study underscores the pivotal role of porous electrodes in improving EC processes and achieving efficient pollutant removal with reduced energy consumption.
Electrocatalytic Synthesis of Pure Aqueous Hydrogen Peroxide Using a Porous Proton Exchange Membrane
Authors: Enomoto Kazuma , Okazaki Takuya , Amano Fumiaki
Published: December 2024

Hydrogen peroxide (H2O2) is a valuable and useful chemical, but its manufacturing process has environmental and cost challenges. Polymer electrolyte membrane-based electrochemical cells have been reported for 2-electron oxygen reduction reactions to produce pure aqueous H2O2. However, state-of-the-art 3-chamber cells with high production rates suffer from large cell resistance. Herein, we developed a novel 2-chamber cell employing a porous proton exchange membrane to facilitate oxygen supply from the anode to the cathode side. The generated H2O2 is easily collected with water flow on the cathode chamber, achieving higher Faradaic efficiency compared to conventional 2-chamber cells. Minimizing the water flow rate at 40 mA cm−2 resulted in an H2O2 concentration of 6000 mg L−1, sufficient for wastewater treatment applications. Continuous electrosynthesis of pure aqueous H2O2 was also demonstrated for 50 hours without cell voltage increase or H2O2 concentration decline. This result indicates that the porous proton exchange membrane was not flooded with liquid water after 50 hours of operation even though water flowed on the cathode chamber. Additionally, electrochemical impedance measurement revealed a cell resistance of 4.2 Ω cm2, which is much lower than that of the 3-chamber cell. The developed electrolyzer, in which oxygen is supplied from the anode side through the porous membrane, offers a novel approach to establish a gas–liquid–solid triple-phase boundary, facilitating electrocathodic H2O2 production with high selectivity and low cell resistance.

Figure 1
Zero-Emission Hydrogen Production at on-Site Hydrogen Refueling Station Using Excess Electricity in Kyushu
Authors: Tachikawa Yuya , Kobayashi Tomotake , Kawakami Keiji , Matsuo Yudai , Kumamoto Yoshiyasu , Morishima Ryoko , Yasutake Masahiro , Sasaki Kazunari
Published: December 2024

Introduction

In Japan, the shift from CO2-emitting energy sources toward carbon neutrality is proceeding rapidly. Approximately 27% of the electricity generated in Japan is generated using zero CO2 emission energy sources including renewable energy. Especially in Kyushu island, located in the western region of Japan, approximately 58% of electric energy is provided by zero-emission power generation, and energy conversion is steadily progressing toward achieving carbon neutrality by 2050. The introduction of offshore wind power and other renewable energy facilities is planned for the Kyushu region in the future, which is expected to further reduce CO2 emissions in the power generation sector. Meanwhile, energy management issues have become apparent, such as the fact that some electricity generated cannot be used due to reasons such as the imbalance between supply and demand of electricity.

In this study, to investigate methods to store and use excess electricity and resolve the imbalance, we aims to clarify the effect of hydrogen production system on imbalance resolution. To evaluate its effect, demonstration studies are currently underway at an on-site hydrogen production type hydrogen station.

Research Issues

In this demonstration study, an on-site hydrogen station has been installed and demonstrated that can produce hydrogen using a water electrolyzer(Hitachi Zosen Corp.), compress hydrogen using a hydrogen compressor(Hydro-Pac. Inc.), and fill hydrogen using a hydrogen supply unit (TATSUNO Corp.) with a pre-cooling heat exchanger (ORION Machinery Co., Ltd.). Energy management equipment that makes effective use of electric power that cannot be used even if generated and equipment that associates the power required when operating facilities with zero-emission power sources have also been installed. And the realization of carbon neutrality for the entire hydrogen station's power consumption, its component power sources, and excess power usage status are being analyzed and examined in this study.

This presentation will report the results and its analysis of the demonstration of hydrogen production by zero-emission power source using the above facilities.

Acknowledgement

This research was supported by New Energy and Industrial Technology Development Organization (NEDO), project No. JPNP14026.
(Invited) Key Challenges in Area Selective Deposition: From R&D Scale to High Volume Manufacturing
Authors: Saly Mark , Bhuyan Bhaskar
Published: December 2024

The semiconductor industry has enjoyed unprecedented growth over the last two decades fueled by the PC/internet era (2000s) and the Mobile/Social Media era (2010s). We are now entering the Artificial Intelligence/Big Data era which is predicted to push the industry towards $1T in revenue by the early 2030s1. AI applications require massive amounts of computational power and power consumption. To keep pace with expected computational demands and ensure that the industry does not put strain on the global power supply, device makers are looking at ways to increase compute while driving lower operational power consumption. The image below showcases TSMC’s device architecture roadmap on new transistor architectures and gives insight into a path on new integrated materials2. After gate-all-around nanosheets (entering trial production today), TSMC will enter the 3D regime with transistor stacking called CFETs (complementary field-effect transistors). 3D integration of devices is a common strategy across the industry from logic to memory to continue scaling trends. Stacking the devices is shown to increase performance, decrease area cost, and decrease power consumption. Realization of these complex architectures requires very stringent and rigorous fabrication steps with various patterning techniques and new processes. Selective deposition has been identified as one primary method to simplify integration schemes to lower complexity and cost. For example, selective deposition can mitigate issues encountered in fine pitch lithography such as edge placement error that can lead to reliability and performance issues like BEOL contact shorts. Applied Materials is the current leader in selective deposition processing, and we have fielded multiple products that are being used to fabricate cutting-edge devices at leading edge customers. This discussion will focus on the trials and tribulations of ASD, and how it is enabling our customers to reduce power consumption while increasing performance all at a lower area cost, which will be crucial to the future sustainability of this industry.

1. https://www.semi.org/en/blogs/semi-news/global-semiconductor-industry-driving-%241-trillion-and-beyond-together

2. TSMC 2023 North America Technology Symposium (April 26th, 2023)

Figure 1
Ultra-Low Loaded Platinum Via Plasma-Enhanced Atomic Layer Deposition for the Fuel Electrode Active Layer in Steam Reversible Solid Oxide Cells
Authors: Kim Hyong June , Li Haoyu , Kim Deahyun , Park Geonwoo , Jo Sung Eun , Ju Kyoungjae , Park Haesun , Lee Min Hwan , An Jihwan
Published: December 2024

Reversible solid oxide cells (rSOCs) are crucial energy devices in sustainable energy systems, offering efficient energy conversion and storage solutions through hydrogen. Conventional SOFC/SOEC operating temperatures are above 700°C; at these temperatures, the cells benefit from high energy conversion efficiencies due to facilitated electrochemical reactions and effective waste heat utilization. Despite their advantages, commercial rSOCs face hurdles including suboptimal performance in the intermediate temperature range of 500-700°C, limited lifespan, and elevated operational costs. Addressing these issues, significant progress has been made in electrode fabrication, particularly through advanced semiconductor fabrication methods such as atomic layer deposition (ALD).

In this study, we explore the application of plasma-enhanced ALD (PEALD) for depositing exceptionally low loadings of platinum on Ni-yttria stabilized zirconia (Ni-YSZ) fuel electrodes, aiming to enhance both performance and stability. Employing this novel approach, we achieved precise control over the Pt nanoparticle deposition process, resulting in a catalyst loading of only 0.2 µg/cm2.

Experimental results demonstrated that rSOC samples with 10 cycles of PEALD Pt exhibited a 20% increase in maximum power density (548 vs. 479 mW/cm2 at 700°C) and an 18% increase in current density (1260 vs. 1070 mA/cm2 at 1.5 V) compared to the bare samples. Notably, these improvements were achieved without any observable performance degradation over 50 hours of operation at 700°C with 50% humidified hydrogen. Density functional theory (DFT) simulations were employed to elucidate the mechanisms contributing to the enhanced activity, revealing that the nano-scale Pt deposition promotes efficient hydrogen oxidation and evolution reactions.

These findings highlight the potential of PEALD for rSOC manufacturing, enabling the creation of highly active and stable electrodes with minimal precious metal loading. The outcomes of this study suggest that such advancements could lead to more economically viable and sustainable hydrogen energy solutions, aligning with broader goals of energy security and environmental sustainability. This work provides a compelling case for the wider application of nano-engineered catalysts in high-performance electrochemical systems at intermediate temperature ranges.
ALD-Imparted Stability on High-Voltage Cathode Materials for Increased Cycle Life and Energy Density in Lithium-Ion Batteries
Authors: Pach Gregory F. , Martinez Madison , DuMont Jaime W , Herbert-Walters Meghan , Dameron Arrelaine A , Hughes Barbara K
Published: December 2024

High-voltage cathode materials such as lithium cobalt oxide (LCO) and nickel manganese cobalt oxide (NMC) are critical for obtaining high energy densities in lithium-ion batteries (LIBs). Although both materials have been implemented in commercially available consumer electronics, the demand for exceedingly higher cell energy densities requires cathodic stability at increased cell potentials. Cycling LIBs to high potentials (≥ 4.4 V) can accelerate degradation modes at the cathode such electrolyte consumption, material phase transitions, transition metal ion dissolution, and oxygen loss. Material engineering strategies such as transition metal doping/alloying or surface coating are often employed to mitigate these failure pathways, however, many of the methods used to realize these solutions are not feasible at industrial scales while also being time, energy, and cost prohibitive.

In this work, we demonstrate how atomic layer deposition (ALD) can be used to stabilize both LCO and single-crystalline NMC materials at high cell potentials in LIBs. Using Forge Nano’s ALD technology, we show how we can deposit thin, homogenous coatings on these cathode materials at industrially relevant scales. Electrochemical testing and differential capacity analysis of cathode half cells at progressively wider voltage windows illustrate that ALD protects and stabilizes the cathode against detrimental side reactions that cause capacity fade and increased internal resistance. Post-cycling SEM-EDX characterization from full cells shows that Co dissolution can be significantly reduced when an ALD coating is deposited on the cathode and that this effect becomes more pronounced at elevated cut off voltages. EIS analysis results demonstrate that ALD protects LCO surfaces from detrimental phase transitions above a 4.5 V upper cut off voltage, suppressing the formation of a spinel layer and shielding the surface from harmful reactions with the electrolyte. Together, these enhancements lead to cycling performances that rival the best performing commercial material investigated in this work, showing that ALD can be a viable and affordable technology for cathode materials enhancement.
Low-Temperature Selective Si:As Epitaxy
Authors: Abdula Daner , Chiu YuJen , Marozas Brendan , Khazaka Rami , Miskin Caleb K , Lee Jung Soo , Demos Alexandros T
Published: December 2024

A selective low-temperature Si:As (LT-SiAs) process is presented which utilizes cyclic deposition-etch (CDE) at <450oC. Selectivity against SiN and SiOx dielectrics and crystallinity are confirmed on gate-all-around (GAA) patterned structures. Hall measurements on blanket wafers show a resistivity minimum of 0.42 mΩ-cm at ~1.7% As for selective LT-SiAs. SIMS profiles of P and As diffusion into intrinsic Si (i-Si) for LT-SiP/LT-SiAs/i-Si and LT-SiP/i-Si stacks show >2× benefit of using LT-SiAs spacers to minimize dopant diffusion for as-deposited, soak-annealed and spike-annealed samples. Improvement is attributed to relatively limited diffusivity of As in Si versus P and the lower As concentration needed for LT-SiAs layer to achieve minimum resistivity relative to LT-SiP (~3%). Lastly, a comparison of LT-SiAs and high-temperature Si:As (HT-SiAs) shows a ~2× reduction of As diffusion into i-Si for LT-SiAs at length scales of >10nm.

[1]: E. Rosseel et al. ECS Trans.
98, 37 (2020).

Figure 1
(Invited) Heterogeneous 3D CFET with Ge Nanosheet Channel
Authors: Kim Sanghyeon , Kim Seongkwang , Lim Hyeongrak , Jeong Jaeyong , Jeong Jaejung , Park Youngkeun , Cho Byungjin , Kim Younghyun
Published: December 2024

Recently, complementary field-effect transistors (CFETs) have been seriously studied for next-generation device architectures to further improve PPA (power, performance, and area). However, there are still many challenges including process integration and structure optimization, decisions on implementation schemes (monolithic or sequential), etc. At the transistor level, unbalanced transport between n- and p-FET would be one of the most critical issues because CFETs inherently require the same width between n- and p-FETs. Here, we will discuss the opportunity of heterogeneous or hybrid channel design to mitigate these issues and its process flexibility to realize CFETs.