bluuebunny/crossref_metadata_2025 huggingface dataset:
Insights into the Electrochemical Reduction of Nitrate on Metal Surfaces
Authors: Zagalskaya Alexandra , Akhade Sneha A , Feaster Jeremy
Published: December 2024

Electrochemical nitrate reduction to ammonia (NO3RR) emerges as a dual-purpose solution, addressing the environmental challenge of wastewater decontamination by removing harmful nitrates and providing a sustainable method for ammonia (NH3) production. This approach offers a viable and green alternative to producing NH3 compared to the traditional energy- and carbon-intensive Haber-Bosch process. However, electrocatalytic conversion of nitrate to ammonia involves a complex 8-electron process, leading to a variety of byproducts, including nitrogen and its oxides. Non-noble transition metals exhibit great potential for this reaction due to their affordability and catalytic activity. In this study, we explore the reaction mechanisms occurring on the surfaces of several face-centered cubic (fcc) transition metals. Our findings indicate that the *NO3 exhibits the strongest binding affinity to the (110) facet, followed by the (100) and (111) facets. In addition, the presence of alkali metal cations in the vicinity of electrode surface plays a crucial role in *NO3 stabilization. Combining density functional theory (DFT) calculations, ab initio molecular dynamics (AIMD) and enhanced sampling methods, we investigate the thermodynamics and kinetics of the NO3RR reaction mechanisms. Specifically, we present a favorable alternative pathway for converting *NO3 to *NO, indicating that the further reduction of *NO is likely the rate-limiting step. The obtained computational results are discussed in the light of the existing experimental data, emphasizing the significance of the combined influence of the electrode and electrolyte in advancing electrochemical nitrate reduction to ammonia.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Tuning Hydrogen Evolution and Oxidation Electrocatalysis through Interfacial Hydrogen Bonds
Authors: Zhang Yirui , Huang Botao , Aggarwal Abhishek , Leverick Graham , Shao-Horn Yang
Published: December 2024

Designing electrochemical water splitting and its reverse process is crucial for fuel cells to achieve high efficiency. Conventional design of catalysts has focused on tuning the surface electronic structures and binding strength of intermediates, while recent studies show that changing electrolyte compositions, such as cations and pH, can also significantly alter catalytic activity, highlighting new opportunities in tuning noncovalent interactions in the electrolytes to control activities. Yet, the mechanistic role of electrolytes and their structures at the electrochemical double-layer remain poorly understood. Challenges arise in characterizing the interface and understanding the reaction mechanisms under operando processes.

In this talk, we tailor non-covalent hydrogen bonding interactions at the electrified interface to control electrochemical proton-coupled electron transfer reactions, and uncover the interfacial molecular mechanisms. We investigate hydrogen evolution and oxidation reactions (HER/HOR) by systematically confining water in organic matrixes. Tuning the hydrogen-bonding networks by changing the water concentration and altering the donor number of organic solvents shifted the onset potentials. High donor number solvents, such as DMSO, suppress HER more significantly due to its stabilization effect of isolated water, while the enhancement effect of HER with low donor number solvents, such as acetonitrile, is due to the promotion of interfacial hydrogen-bonded water. In situ surface-enhanced infrared absorption spectroscopy (SEIRAS) measurements and molecular dynamics simulations provide further support to the changes in interfacial hydrogen bonding during the reactions. These findings provide design principles for electrolytes and open up immense opportunities for using non-covalent hydrogen bonding interactions at the electrified interface to control the kinetics. The understanding would also be impactful across other reactions involving proton-coupled electron transfer that are crucial for energy storage, such as CO2 reduction and aqueous batteries.
(Invited) Linking Electric Double Layer Formation to Electrocatalytic Activity
Authors: Gebbie Matthew A.
Published: December 2024

Electric double layers form at electrode-electrolyte interfaces and often play defining roles in governing electrochemical reaction rates and selectivity. While double layer formation has remained an active area of research for more than a century, most frameworks used to predict double layer properties, such as local ion concentrations and potential gradients, remain rooted in classical theory, which neglects ion-ion interactions and assumes non-reactive interfaces. Yet, recent findings from the surface forces and electrocatalysis communities have highlighted how the emergence of ion-ion interactions fundamentally alters electric double layer formation mechanisms and interface properties. This is especially true in ionic liquid-derived electrolytes, where studies show that ionic correlations can substantially alter reaction rates and selectivity. I will present our work aimed at linking nanoscale structures and dynamics of ionic liquid-solid interfaces to the rates and selectivity of CO2 electrochemical reduction as a model system for illuminating how collective ionic assembly influences electrocatalytic activity. I will also highlight our work bridging surface forces measurements with electrochemical analysis to understand how ion clustering and nanoscale assembly influences interfacial properties. I will conclude with our perspective on how advances from the electrocatalysis community open the door to using reaction rates and selectivity as powerful tools to study electric double layer formation in concentrated electrolytes.
Incorporation of Trace Metals through in situ Cation Exchange Reactions: Electrochemical and Structural Effects on Nickel Oxyhydroxide Electrocatalysts
Authors: Marquez Raul A. , Kalokowski Emma , Espinosa Michael , Bender Jay T , Son Yoon Jun , Kawashima Kenta , Chukwuneke Chikaodili E. , Smith Lettie A , Celio Hugo , Dolocan Andrei , Zhan Xun , Miller Nathan , Milliron Delia J , Resasco Joaquin , Mullins C Buddie
Published: December 2024

Understanding how electrocatalysts evolve during operation is critical to optimizing their performance. The oxygen evolution reaction (OER) exposes electrocatalytic materials to harsh conditions that lead to significant transformations. A discovery that revolutionized OER catalysis was the dramatic improvement in activity due to the intentional, or incidental, in situ incorporation of Fe into Ni and Co oxyhydroxides. This finding raised questions about the true active phase in OER catalysts. While Fe incorporation is now widely acknowledged, there is still significant room for improvement in comprehending the in situ incorporation of trace metals and its effects on the electrochemical and structural properties of transition metal oxyhydroxides.

We report a comprehensive investigation of in situ metal incorporation on nickel oxyhydroxide OER electrocatalysts encompassing four multivalent cations: Fe, Co, Mn, and Cu. We found that adding trace amounts of these to alkaline electrolytes alters the electrocatalytic and energy storage properties of NiOxHy films. As opposed to the well-known increase in OER activity induced by Fe incorporation (Figure 1a), in situ incorporation of trace Co and Mn increases the redox capacitance (Figure 1b), while Cu incorporation does not proceed. Depth profiling measurements reveal that metal incorporation is confined to the film's surface (Figure 1c-d), resulting in an interstratified structure that partially retains the more active, disordered phase. We describe four factors determining the occurrence of in situ metal incorporation, underscoring its nature as a cation exchange reaction. Finally, Fe and Co cation exchange processes are manipulated by shifting the solubility equilibrium and through ion complexation. By providing a better understanding of in situ metal incorporation processes, our results underscore its potential as a strategy for manipulating the surface chemical composition.

Figure 1
Tuning Water at the Solid–Liquid Interface for Durable Electrocatalysis
Authors: Cho Junsic , Kim Haesol , Lim Taejung , Kim Jinjong , Joo Sang Hoon , Choi Chang Hyuck
Published: December 2024

The solid–liquid interface is one of the oldest and most fundamental concepts in electrochemistry. However, the interface consists of various elements — such as electrode, solvent, cation, anion, reactant, product, etc. — and its microscopic structure remains elusive and a great challenge. Here, we show that the ionomer can selectively control the water properties at the electrode-electrolyte interface, which directly or indirectly affects electrocatalytic performance. Advanced online spectroscopic studies revealed that the change in water properties due to introduction of the ionomer layer led to superior stability of the carbon-supported catalyst with alleviated carbon corrosion. Overall, in this work, we elucidate that interfacial water is one of the key factors for electrocatalytic performance and consider the introduction of an ionomer layer as an appropriate methodology to selectively control it at the solid-liquid interface.
Electrochemical Reduction of CO2 to Methane Using a Mixed Gas Feed
Authors: Sit Chun Yat , Kenis Paul J.A
Published: December 2024

The increasing atmospheric carbon dioxide (CO2) concentration and the associated rise in global temperatures are major global concerns. One mitigation strategy being studied and employed is Carbon Capture and Storage (CCS). Another widely studied mitigation approach is Carbon Capture and Utilization (CCU), where CO2 is utilized as the feed for chemical production. The electro-reduction of CO2 (eCO2RR) is a promising technology that can convert captured CO2 to key intermediates such as carbon monoxide, methane, ethylene, and ethanol, depending on the catalyst used and its selectivity. Most eCO2RR studies use close to pure CO2 streams as the feed, whereas actual feeds at scale from direct air capture or other capture processes may not be close to 100% CO2, and may contain other contaminants.

Our work explores eCO2RR using feeds that are less than 100% CO2 but still contain substantial fractions of N2 and/or O2. Specifically, this presentation will focus on developing an electrochemical CO2 reduction approach using a mixed gas feed comprised of O2, N2, and CO2 for CH4 production. To mitigate the detrimental effects of the presence of O2 on the eCO2RR rate and selectivity, we employ an electrochemical method to remove O2 in the first step, followed by the electroreduction of CO2 to CH4 in a membrane electrode assembly cell. This two-step strategy is expected to achieve a higher selectivity for CO2 to CH4 than the direct reduction of CO2 (still in the presence of O2) to CH4. This work will also investigate the effects of cell flow pattern design, electrolyte, resilience in the presence of O2, and performance of CO2 to CH4 over multi-hour runs.
Electrocatalytic Functionalized Specialty Paper As Low-Cost Porous Transport Layer Material in CO2-Electrolysis
Authors: Stamatelos Ilias , Rentzsch Michael , Liu Chengyu , Bauer Franziska , Pasel Joachim , Barwe Stefan , Robert Marc
Published: December 2024

Efficiently harnessing excess atmospheric carbon dioxide (CO2) is crucial for closing the carbon cycle effectively. Electrochemical CO2 reduction (ECR) holds significant promise for producing valuable products and environmentally friendly chemicals. Carbon monoxide (CO) stands out as one of the most economically viable products of ECR.[1,2] While noble metals commonly catalyze CO2-to-CO conversion, alternative non-noble catalysts are essential for cost reduction. Molecular catalysts like cobalt phthalocyanine (CoPc) offer high ECR activity but limited stability (< 10 h).[3–5] Moreover, the production cost of porous transport layers (PTLs) significantly impacts ECR electrolyzer costs, with commercial carbon-PTLs adding a 20% increase.[6–8] Our work focuses on developing low-cost, non-woven cellulose-based porous PTLs for electrochemical CO2-to-CO conversion. By depositing a cobalt phthalocyanine (CoPc) catalyst layer over our PTLs, we fabricated ECR-functioning gas-diffusion-electrodes (GDEs) for both flow-cell and zero-gap electrolyzers. Under optimal conditions, the Faradaic efficiency of CO (FECO) reached 92 % at a high current density of 200 mA cm−2. Furthering the architecture of the GDEs, CoPc was incorporated into the initial PTL slurry, forming ECR-active PTLs without the need for an additional catalyst layer. The new GDE architecture favored the CoPc-distribution by enhancing the contact and interactions with the carbon substrate and demonstrated a stable electrolysis process for over 50 h in a zero-gap electrolyzer at 200 mA cm−2 with a FECO of 80 %.[9] This study marks a substantial breakthrough in developing for the first time, paper-based functionalized PTLs for the ECR. Marking a significant contribution to the progression of the ECR into practical implications.

[1] M. Jouny, W. Luc, F. Jiao, Ind. Eng. Chem. Res. 57 (2018) 2165–2177.

[2] G.O. Larrazábal, A.J. Martín, J. Pérez-Ramírez, J. Phys. Chem. Lett. 8 (2017) 3933–3944.

[3] S. Ren, D. Joulié, D. Salvatore, K. Torbensen, M. Wang, M. Robert, C.P. Berlinguette, Science 365 (2019) 367–369.

[4] C. Costentin, S. Drouet, M. Robert, J.-M. Savéant, Science 338 (2012) 90–94.

[5] M. Wang, K. Torbensen, D. Salvatore, S. Ren, D. Joulié, F. Dumoulin, D. Mendoza, B. Lassalle-Kaiser, U. Işci, C.P. Berlinguette, M. Robert, Nat. Commun. 10 (2019) 3602.

[6] A.J. Navarro, M.A. Gómez, L. Daza, J.J. López-Cascales, Sci. Rep. 12 (2022) 4219.

[7] B. Yarar Kaplan, L. Işıkel Şanlı, S. Alkan Gürsel, J. Mater. Sci. 52 (2017) 4968–4976.

[8] R.I. Masel, Z. Liu, H. Yang, J.J. Kaczur, D. Carrillo, S. Ren, D. Salvatore, C.P. Berlinguette, Nat. Nanotechnol. 16 (2021) 118–128.

[9] I. Stamatelos, M. Rentzsch, C. Liu, F. Bauer, S. Barwe, M. Robert, ChemCatChem n/a (n.d.) e202300980.

Figure 1
(Keynote) From Electrode Development to Process Optimization: A Journey of Scaling-up CO2 Electrolysis
Authors: Janaky Csaba
Published: December 2024

Electrochemical reduction of CO2 is a promising method for converting a greenhouse gas into value-added products, utilizing renewable energy. Novel catalysts, electrode assemblies, and cell configurations are all necessary to achieve economically appealing performance. In this talk, I am going to present a zero gap electrolyzer cell, which converts gas phase CO2 to products without the need for any liquid catholyte. I will demonstrate how multiple cells are connected into a stack, thus scaling up the electrolysis process. I will show how proper cell components and operational conditions result in industrially relevant performance. I will demonstrate the role of each component of the membrane electrode assembly, such as the catalysts, the porous transport layers, the membrane, and the ionomers.

In the second part of my talk, I will show that while precipitate formation in the cathode gas diffusion electrode is detrimental for the long-term stability, the presence of alkali metal cations at the cathode improves performance. To overcome this contradiction, I will present different approaches which help to extend the lifetime of the electrolyzer cell. I will also present a detailed electrolyte and water balance of the operational cell, to better understand the contributing factors to these phenomena. As an outlook, I will present a complex machine learning based approach, through which we aim to find the optimal operating conditions of such CO2 electrolyzer cells.

Finally, I will share the most recent insights on our containerized prototype CO2 electrolyzer system, capable of processing 100 t CO2/year.
Immobilized Molecular Catalysts for Heterogeneous Electrochemical H2 Evolution (HER) and CO2 reduction (CO2RR)
Authors: DeMonte Kieran , Bennington Michael , Marshall Aaron Timothy , Brooker Sally
Published: December 2024

The global use of fossil fuels results in unsustainable levels of CO₂ gas being released into the atmosphere, furthering the impacts of global warming.¹ Possible capture of CO₂ from high emission processes and subsequent selective reduction (CO₂ reduction reaction, CO₂RR) to convert it into renewable fuels could move those processes towards carbon neutrality.

To move towards carbon zero, green hydrogen is a desirable alternative to fossil fuels. Hydrogen has a higher energy density and only produces water as a waste product. ‘Green’ hydrogen is produced from water using renewable energy (hydrogen evolution reaction, HER). Most hydrogen produced currently, for use in industry, is ‘grey’ hydrogen made from fossil fuels in energy intensive and carbon emitting processes, so this must also be replaced by green hydrogen.

The HER and CO2RR are energy intensive processes so catalysts are needed to reduce the energy of these chemical processes, to make them more energy and cost efficient.² The CO₂RR is a process with many possible products, highlighting the need for catalysts that can not only reduce the energy required for reduction but also produce the desired useful products selectively.

We have prepared a range of porphyrin-like dimetallic macrocyclic complexes³,⁴ and these are now being tested for electrocatalytic activity for HER and CO₂RR. This testing is being carried out under heterogenous conditions, through immobilisation of the catalysts on solid supports. This presentation will cover the synthetic steps involved in producing these macrocyclic complexes and the results of the heterogeneous electrochemical HER and CO₂RR testing on selected complexes.

1. Tollefson, J., The hard truths of climate change - by the numbers. Nature 2019, 573 (7774), 324-327.

2. Dalle, K. E.; Warnan, J.; Leung, J. J.; Reuillard, B.; Karmel, I. S.; Reisner, E., Electro- and solar-driven fuel synthesis with first row transition metal complexes. Chem. Rev. 2019, 2752-2875.

3. Li, R.; Mulder, T. A.; Beckmann, U.; Boyd, P. D. W.; Brooker, S., Dicopper(II) and dinickel(II) complexes of Schiff-base macrocycles derived from 5,5-dimethyl-1,9-diformyldipyrromethane. Inorganica Chimica Acta 2004, 357, 3360–3368.

4. Malthus, S. J.; Cameron, S. A.; Brooker, S., Improved access to 1,8-diformyl-carbazoles leads to metal-free carbazole-based [2+2] Schiff base macrocycles with strong turn-on fluorescence sensing of zinc(II) ions. Inorg. Chem. 2018, 57, 2480–2488.
Influence of Annealing Parameters on the Photoelectrochemical Performance of Spaced TiO2 Nanotubes
Authors: Son Younggon , Jung Rin , Lee Kiyoung
Published: December 2024

Fossil fuels, currently comprising 80% of global energy consumption, are major contributors to environmental pollution due to their substantial carbon emissions. In contrast, hydrogen energy, characterized by its high energy density and zero carbon emissions, is increasingly recognized as a promising alternative energy source. Among the various hydrogen production technologies, photoelectrochemical (PEC) water splitting stands out as a leading method for generating clean hydrogen. Titanium dioxide (TiO2) is the most widely studied material for PEC hydrogen production, as it forms electron-hole pairs upon absorbing light with wavelengths shorter than 400 nm (3.0 to 3.2 eV), thereby enabling water splitting.

Crystalline TiO2 exists in three phases: anatase, rutile, and brookite, with anatase being recognized for its superior PEC properties. However, some studies have reported that mixed-phase anatase-rutile TiO2 exhibits higher PEC activity than pure anatase. Anodization is a general method for forming nanostructures to enhance the PEC efficiency of TiO2. Anodizing a titanium metal substrate in a fluoride ion-containing electrolyte produces one-dimensional nanotube structures. The length, inner diameter, and spacing of these tubes can be precisely controlled by adjusting the anodization conditions. In this study, spaced TiO2 nanotubes (SPNTs) with wide inter-tube spacing were fabricated via anodization, and their structural, physical, and PEC properties were analyzed based on annealing temperature and atmosphere. Under optimized annealing conditions, the SPNTs exhibited a mixed anatase-rutile phase, a photocurrent of 0.34 mA/cm² at 1.23 V vs RHE, and a charge transfer resistance of 556 Ω at open circuit potential.
Sweet Spot in Oxidation Temperature Enhances Conductivity and Oer Activity for IrO2-Coated SnO2 Nanofibers
Authors: Wang Shizhe , Kost Melisande , Dushimineza Felix , Döblinger Markus , Müller-Caspary Knut , Bein Thomas
Published: December 2024

Solutions for effective energy conversion and storage are needed for the shift from fossil fuel-based, CO2-intensive energy production to a future sustainable energy-based economy. This way green energy from renewable sources, such as solar or wind power, may later be re-electrified. One option is to use water electrolysis to transform energy from renewable sources into chemical energy in the form of hydrogen. Proton Exchange Membrane (PEM) electrolysis is a potent, cutting-edge technique that leverages rare iridium-based catalysts to boost the oxygen evolution reaction (OER) to solve this issue. Reducing the total density of iridium-based catalysts for the OER requires minimizing the usage of rare and valuable iridium, which will enhance the PEM process's sustainability and economics.

Here we present an investigation aimed to further reduce the iridium usage for proton-exchange membrane (PEM) electrolysis. First, SnO2 nanofibers are produced utilizing a water-free alkoxide route. A wet-chemical method is then used to deposit nanoparticulate IrO(OH)
x
on the filaments. After subsequent oxidation at various temperatures, the final OER active catalyst is obtained.

With the emphasis on reaching high activity, stability, and conductivity at the laboratory level, ultra-small interconnected IrO
x
/IrO2 nanoparticles anchored to electrospun SnO2 nanofibers (IrO
x
/IrO2@SnO2) and associated percolation pathways are investigated. The utilization of transmission electron microscopy (TEM) in scanning mode (STEM) before and after electrocatalytic reactions provides insights into the oxidation and crystallization state of iridium oxide nanoparticles dependent on temperature and upon catalytic use. This enables an understanding of further possible reduction of iridium content by optimizing synthesis parameters. The data indicate that the optimal iridium utilization is achieved at 375°C oxidation temperature, with the highest resulting conductivity and electrochemical activity. Furthermore, TEM data reveal initiation of crystallization of IrO2 in the temperature window between 365 and 375°C. The pivotal role of conductivity in electron transport to active sites is underscored by cyclic voltammetry (CVA) measurements, which provide further insight regarding performance and stability with a view on future PEM electrolysis applications. These findings not only enhance our fundamental understanding but also offer practical strategies for advancing cost-effective and efficient electrolysis technologies.
(Invited) Reaction-Based Microcantilever Sensors
Authors: Ji Haifeng
Published: December 2024

Microcantilevers (MCLs) have proven to be a cost-effective, label-free, and portable analytical technique for the detection of chemical and biological species. The MCL method offers significant benefits, primarily owing to its high sensitivity, which enables the detection of cantilever motion with sub-nanometer precision. Additionally, this method is well-suited for fabrication into a multi-element sensor array, further enhancing its capabilities. Most of the sensors are based on adsorption-induced frequency or surface stress changes of MCLs. Multiple review articles on this concept have been published, but no review has been published summarizing the MCL sensors with a focus on reactions. Other than detecting chemical species, another unique application of MCLs is their ability to characterize the morphology and mechanical properties of materials on a solid-liquid or solid-gas interface during a reaction process. We will review the reaction-based MCL sensors and also their potential applications in monitoring reactions in this short review article.
Monitoring Water Quality in Navajo Nation Using Paper-Based Electrochemical Sensors
Authors: Billey Wayant , Platero Justin , Platero Joshua , Begay Makeiyla , Wilson Katelyn , Plummer Dallen , Nelwood Michael , Abdelazim Khaled , Soundappan Thiagarajan
Published: December 2024

The NSF-Prem research collaborative effort between Navajo Technical University and Harvard University aims to address the critical issue of water contamination within the Navajo Nation. Through decades of uranium mining and mineral extraction has left a lasting mark on the Navajo land and groundwater resources, necessitating effective solutions. The Nana Electrochemical Analysis and Energy Storage Laboratory (NEST LAB) at NTU has developed flexible paper-based integrated with advance electrochemical techniques to detect heavy metal concentrations in water samples. These sensors are printed out of a wax printer on chromatography paper, and we manually coat eighteen sensors per sheet with carbon conductive paste to offer a cost-effective, easy to fabricate, and highly reliable, offering real-time monitoring capabilities. The project is new, and the core goal is to expedite water quality analysis and empower the Navajo community to detect potential contamination promptly. We have not yet distributed these sensors to the community to acquire hard data, but we are expecting in the future to distribute them to local chapter houses, so that residents can independently assess groundwater quality, foster a sense of ownership and proactive environmental stewardship. This partnership exemplifies the power of community-driven solutions and trains Navajo students to get involved in scientific innovations to safeguard the environment for future generations in the Navajo Nation.

Fund Support: NSF-PREM DMR-2122195 USDA-NIFA-2024-38424-41474
Sensors for Inflatable Lunar Habitat Construction
Authors: Ahn Hosang
Published: December 2024

Lunar habitat is necessary for human exploration, especially for long duration space missions. For lunar habitat consturction, there are several other environmental hurdles to overcome than earth and constant internal pressure of habitat is added if the structure is to be inflatable.

Among these hurdles, high energetic ions and particles from solar radiation and consequence extreme temperature difference may be protected with higher priority at least to secure survival environment for humans.

In Korea Institute of Civil engineering and building Technology, new research project was launched in 2023 to design basic plan of lunar habitat construction on the moon and one of research topics is how to secure indoor environment of inflatable lunar habitat under that harsh lunar environment.

Multi layred shell structured wall was suggested from previous project and research results and was selected to the optimum initial structure to start. Multi layred shell is mainly consisted of several highly strong and heat resistant fabric such as Kevlar or Vectran in webbing with other ion or particle protective layers and thermal insulation.

Key environmental parameters for monitoring are internal air pressure, oxygen cencentration, temperature, humidity, and high energy particles by secondary radiation. Therefore, it is essential how to design and configure total sensing and monitoring system for inflatable habitat for long duration human exploration. Environmental, radiation, and inflatable structure monitoring sensors are summarized and composed to secure indoor enviroment and provide environmental quality data to HVAC system in further.
Fabrication of CuO NP for NO2 Gas Sensing
Authors: Kim Sangwoo , Choi Myung Sik
Published: December 2024

NO2 is a very dangerous gas that is mainly emitted from fossil fuels and is a major cause of air pollution. It has environmental problems cause by acid rain and has a bad effect on human health. In this study, mesoporous CuOx nanoparticles (NPs) were successfully synthesized using a low-temperature sol–gel method. Subsequently, the synthesized NPs were annealed at temperatures of 250, 350, and 450 °C. The Properties of the synthesized samples showed that the size of NPs increased with increasing annealing treatment, while the surface area decreased. The samples annealed at 250°C/2h exhibited significantly higher surface area compared to the samples annealed at 350°C and 450°C, thanks to their finer particle size and mesoporous properties. Resistive gas sensors incorporating these samples were successfully fabricated and tested for sensitivity towards both NO2 (oxidizing gas) and H2S (reducing gas) at 200 °C. The sensor with the mesoporous CuOx NPs annealed at the lowest temperature (250 °C) exhibited an enhanced response to NO2 gas but no response to H2S. The strong response to NO2 gas is considered to be due to the high surface area of the sensing layer which provides plenty of adsorption sites for gas molecules and the oxidizing nature of NO2 gas with high affinity to electrons. These findings highlight the effectiveness of the sol–gel method in synthesizing CuO NPs for gas sensing, as well as the need for optimizing the annealing temperature to maximize the sensor response.
Low-Cost Paper-Based Device Integrated with Nanomaterial-Based Electrochemical Immunosensors for Sensitive Detection of Pancreatic Cancer
Authors: Li Xiujun James , Prasad Kariate Sudhakara
Published: December 2024

Due to the lack of specific early detection methods for pancreatic cancer, it usually goes undetected until its advanced stage. By employing paper-based electrodes (PPE), herein we for the first time developed a disposable low-cost paper-based immunosensor for rapid early quantitative detection of pancreatic cancer with a new biomarker, pseudopodium-enriched atypical kinase one, SGK269 (PEAK1). The immunosensor was constructed by fabricating PPEs immobilized with the versatile nanomaterial, graphene oxide, for the incorporation of antibodies to form an immunosensing platform, without the need of complicated surface modification. After it was confirmed that the PPEs exhibited excellent electrochemical properties, a sandwich-type electrochemical immunosensor was subsequently constructed by employing graphene oxide layers immobilized with anti-PEAK1, and the antibody conjugated with gold nanoparticles (AuNPs-tagged-Anti PEAK1). Further, spectral and surface characteristic studies confirmed the formation of the immunosensing platform. The immunosensor for PEAK1 exhibited a wide linear range between 10 pg/mL and 106 pg mL-1 with a low limit of detection (LOD) of 10 pg mL-1. The obtained results point towards rapid, sensitive, and specific early diagnosis of pancreatic cancer and other types of cancer at the point of care and other low-resource settings.
Integrating Electrokinetics with AI-Assisted Raman Spectroscopy for Bacterial Detection in Wastewater
Authors: Zhang Yirui , Herndon Liam , Padhy Punnag , Al-Zubeidi Alexander , Ogunlade Baba , Stiber Ariel , Boehm Alexandria , Dionne Jennifer
Published: December 2024

Wastewater-based epidemiology can monitor population-level infection, provide early warnings about disease outbreaks, and help control disease spread at the community level [1,2]. However, broad-spectrum bacterial identification in wastewater presents outstanding challenges; notably, current culturing or fluorescence-based methods [3] to identify bacteria are unsuitable for real-time, high-throughput screening of diverse bacterial species, and may not work well in the complex wastewater matrix. Here, we harness electrokinetics and artificial intelligence (AI)-powered Raman spectroscopy as an innovative approach that promises the identification of a wide range of pathogenic bacteria in wastewater.

First, we synthesize gold nanorods that can electrostatically bind to bacteria surfaces, allowing for surface-enhanced Raman spectroscopy (SERS) [4] from cell surfaces. We collect SERS from bacteria spiked into filter-sterilized wastewater, including Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli, spanning concentrations from 109 cells/mL to 104 cells/mL. Spectral clustering analysis shows that bacterial signals become less distinguishable in wastewater as the concentrations decrease. To overcome this challenge, we incorporate electrokinetic effects into SERS by employing gold microelectrodes to apply electric fields, utilizing dielectrophoresis (DEP) [5] to rapidly displace and concentrate bacteria. The four types of bacteria responded to 5-100 kHz AC fields based on their different dielectric responses and sizes, and were enriched at the microelectrode within minutes. The enrichment of bacteria is directly visualized through optical and electron microscopy, resulting in up to tenfold increases in Raman signal intensities under electrical fields at bacterial concentrations down to 104 cells/mL. Such enhancement may enable the detection sensitivity to reach environmentally relevant concentrations. Importantly, mixtures of bacteria are now distinguishable from SERS under DEP effects. Finally, employing random forest and convolutional neural network models [6], we identify biologically relevant Raman fingerprint peaks characterizing proteins, nucleic acids, and lipids from bacteria surfaces, allowing for rapid identification of bacteria species in wastewater. We also discuss integrating our method with microfluidic devices to monitor complex wastewater samples. Our method can enable generalized pathogen detection and molecular recognition in complex liquid samples, such as wastewater, blood, and seawater.

[1] Hellmér, et al. Applied and environmental microbiology. (2014).

[2] Keshaviah, et al. The Lancet Global Health. (2023).

[3] Jahn, et al. Nature Microbiology. (2022).

[4] Tadesse, et al., Nano Lett. (2020).

[5] Pethig. John Wiley & Sons (2010).

[6] Ho, et al., Nat. Comm. (2019).
(Digital Presentation) Integration of Multiple Input Multiple Output Underwater Wireless Power Transfer in a Renewable Offshore Facility
Authors: Siueia Cátia
Published: December 2024

Hydrogen floating production storage is a promising approach to reduce the negative impacts of carbon dioxide emissions.

In this paper, we propose to investigate multiple input multiple output (MIMO) underwater wireless power transfer in a renewable offshore facility for self charging of a renewable offshore facility.

We consider a nonlinearity of the antenna to maximize the output direct current (DC) power along with radio frequency.

The results reveal that the integration of MIMO underwater wireless power transfer in a renewable offshore facility can notably reduce operation cost, additionally it can lower leakage currents, and it is safe.
Asthma Phenotyping Via Multiplex Detection of Cytokines on an Electrochemical Sensor
Authors: Churcher Nathan , Prasad Shalini
Published: December 2024

Asthma, a complex and diverse lung condition, is typically associated with chronic airway inflammation. Asthma classification has traditionally relied on clinical symptoms and treatment response. As our understanding of asthma’s heterogeneity grows, phenotyping has become a focus. Cytokines, essential chemical messengers in the immune system, play a pivotal role in the mediation of chronic diseases. They facilitate communication between immune cells and directly impact inflammation. Various cytokines have been implicated in asthma pathogenesis. Leveraging cytokines for asthma phenotyping is valuable, as identifying and quantifying these inflammatory mediators can lead to more precise, targeted treatments. To achieve this, we have developed a customizable electrochemical platform for multiplexed detection of select cytokines for non-invasive cytokine detection in saliva. This platform rapidly detects cytokines within physiological ranges and will aid physicians in asthma phenotyping and treatment planning especially for severe asthmatics.

The detection platform leverages subtle changes in impedance at the electrode-electrolyte interface as a function of the chemical interaction between specific antibody-antigen interactions to establish a calibration dose response curve. The platform’s capability to detect and quantify the cytokines in human saliva is demonstrated through spike and recovery experiments.
Electrochemical Simultaneous Determination of Biohazardous Polyphenols Using a Novel Mesoporous Nickel-Modified Carbon Sensor
Authors: Xue Yilei , Noroozifar Meissam , Kerman Kagan
Published: December 2024

The widespread occurrence of endocrine disruptor compounds in wastewater has garnered significant attention owing to their toxicity, even at low concentrations, and their persistence in the water body. Among various analytical techniques, electrochemical sensors have become the preferred tools for the environmental monitoring of water pollutants due to their low cost, rapid detection, high sensitivity, and selectivity [1,2]. In this study, the mesoporous Ni (MNi) material was synthesized with an innovative method using Pluronic™ F-127 as a soft template and applied as a modifier for the simultaneous electrochemical sensing of hydroquinone (HQ), catechol (CC), bisphenol A (BPA), and bisphenol S (BPS) [3]. MNi with high porosity efficiently enhanced the redox-active surface area and conductivity of the glassy carbon electrode contributing to a significantly improved sensitivity in the detection of target chemicals. The pore size and surface area of MNi were estimated based on atomic force microscopy. The limit of detection for HQ, CC, BPA, and BPS was determined to be 5.3, 5.7, 5.6, and 61.5 nM, respectively. The electrochemical sensor presented in this study holds promise as a platform for developing portable and miniaturized tools offering the rapid and sensitive detection of these biohazardous polyphenolic compounds in environmental water samples.

References

G. Hanharan et al., J. Environ. Monit. 2004, 6, 657-664.

S. Sultana et al., J. Electroanal. Chem. 2021, 899, 115644.

Y. Xue et al., Chemosphere 2023, 342, 140003.
Multiplex Pulsed Current Sensors for Anion Detection
Authors: Mehregan Shima , Gopaul Colin S. , Koenig Henry D. , Murphy Will E.M , Veal Charlie T. , Anderson Derek T. , Young Matthias J.
Published: December 2024

Low-cost and stable sensors are needed for long-duration monitoring of nitrate and phosphate in waterways to help improve farming practices and understand the negative environmental and economic impacts caused by the release of these ions. One established platform that shows promise for detecting these ions is the use of solid-contact ion selective electrodes (SC−ISEs). Conventional SC-ISE measurements monitor electrode potential under open circuit conditions to quantify the amount of one target analyte. These conventional SC-ISEs rely on highly engineered membrane materials that are formulated to selectively bind to the target ion. These engineered membrane materials can achieve high selectivity for nitrate and phosphate, but are vulnerable to certain interferents, require frequent calibration, and have poor long-term stability. In recent work, we demonstrated the use of pulsed current technique for anion detection in SC-ISEs, which allows for anion detection based on differences in anion diffusion through the membrane rather than selective anion binding – opening up a wide range of materials as candidates for ion sensing membranes. In this report, we employ pulsed current measurement to examine anion detection using three common polymers as membrane layers: polyvinyl acetate (PVA), polyvinylchloride (PVC), and polyacrylonitrile (PAN). We measure the potential vs. time response for these three membrane materials in solutions containing various anions such as nitrate, phosphate, chloride, and carbonate at varying pulse currents. Afterwards, we employ tree-based and neural-based machine learning algorithms to examine the feasibility of detecting multiple ions simultaneously using the combined response data from multiple electrodes. Our experiments illustrate that our method for anion detection, used with machine learning analysis, is useful for investigating the interaction mechanisms of anions with the polymer matrix.
(Digital Presentation) Electrochemical Detection of Analgesic Acetaminophen Using Sensor Comprised of Low-Cu2+-Doped CoFe2O4 Nanoparticles from Glycerol-Assisted Synthesis
Authors: Alfonso González Jose Guillermo , Granja Claudia Patricia , Morales Jimmy , Dector Andrés
Published: December 2024

This work devised a simple glycerol-assisted synthesis of a low-Cu2+-doped CoFe2O4 and the elec-trochemical detection of acetaminophen (AC). During the synthesis, several polyalcohols were tested, indicating the efficiency of glycerin as a cosolvent, aiding in the creation of electrode-modifier nanomaterials. A duration of standing time (eight hours) before calcination produces a decrease in the secondary phase of hematite. The synthesized material was used as an electrode material in the detection of AC. In acidic conditions (pH 2.5), the limit of detection (LOD) was 99.4 nM, while the limit of quantification (LOQ) was found to be (331 nM). The relative standard deviation (RSD), 3.31%, was computed. The enhanced electrocatalytic activity of a low-Cu2+-doped CoFe2O4-modified electrode Cu0.13Co0.87Fe2O4/GCE corresponds extremely well with its resistance Rct, which was determined using the electrochemical impedance spectroscopy (EIS) technique and defined its electron transfer capacity. The possibility of a low-Cu2+-doped CoFe2O4 for the electrochemical sensing of AC in human urine samples was studied. The recovery rates ranging from 96.5 to 101.0% were obtained. These findings suggested that the Cu0.13Co0.87Fe2O4/GCE sensor has outstanding practicability and could be utilized to detect AC content in real complex biological samples.

References

Alfonso-González, J.G.; Granja-Banguera, C.P.; Morales-Morales, J.A.; Dector, A. A Facile Glycerol-Assisted Synthesis of Low-Cu2+-Doped CoFe2O4 for Electrochemical Sensing of Acetaminophen. Biosensors 2023, 13, 997
Functional Group Discrimination of Neurotransmitters: A MOF-Based Electrochemical Sensor Array Approach
Authors: Kim Hyunro , Park Sungwook , Lee Kwan Hyi
Published: December 2024

In the realm of small-molecule analysis, specifically neurotransmitters, the use of extended-gate field-effect transistor (EG-FET) transducers face hurdles due to the absence of target-specific receptors and interference from high-ionic-strength media. To address this challenge, our study introduces a novel approach employing two-dimensional conductive metal-organic frameworks (MOFs) as sensing components for EG-FET biosensors targeting neurotransmitters. By applying thin films of conductive MOFs onto the extended gate of EG-FET, we achieved remarkable sensitivity, enabling the detection of catecholamines in physiological solutions, even at an ultra-low concentration of around 2nM. The adsorption of analytes within the MOFs led to consistent voltage shifts, effectively mitigating the Debye shielding effect, regardless of the ionic strength of the sensing media. Furthermore, our research demonstrated the potential of a diverse MOF sensor array to distinguish chemically similar neurotransmitters through unique adsorption patterns, attributed to the tunable physicochemical properties of MOFs, such as pore size and surface characteristics. Notably, our study showcased the MOF sensor array's ability to simultaneously discriminate neurotransmitters amidst the presence of biologically relevant substances and artificial cerebrospinal fluid, highlighting its robustness in complex environments.
A Fully Integrated Handheld Electrochemistry Dx Platform for Diabetic Ketoacidosis Monitoring
Authors: Holmes Joanne , Bunga Yousillya , Sanchez Pablo Lozano , Caffio Marco , Kanyong Prosper , Ho Caitlin
Published: December 2024

Ketone bodies, primarily including acetone, acetoacetate, and β-hydroxybutyrate, are byproducts of fat metabolism that accumulate in the body during periods of low carbohydrate intake, prolonged fasting, or uncontrolled diabetes. Elevated levels of ketone bodies in the body is a delayed indicator of the severity of ketoacidosis, an increase in the blood acidity which can disrupt normal bodily functions and become life-threatening if not treated promptly. Traditional methods for detecting ketone bodies in urine include colorimetry and enzymatic assays such as nitroprusside assay. These methods are often limited by specificity, response time and sensitivity. Square wave voltammetry (SWV) was employed to investigate the 3D carbon nanomaterial, Gii, based sensor's electrochemical behaviour. Calibration curves were established using standard solutions of lithium acetoacetate spiked into artificial urine samples. Devices were modified with reagents containing the enzyme, β-Hydroxybutyrate Dehydrogenase, (3-HBDH). Different concentrations of ketones (lithium acetoacetate, LiAcAc) spiked in artificial urine were analysed. The resulting calibration plots were found to be linear from 0 to 5 mM, with R2 > 0.98; which is deemed to be satisfactory for the analysis of ketones in clinical samples. This study presents a novel and efficient sensor for the detection of ketones for urinalysis, offering a significant improvement in terms of sensitivity, specificity, and rapid detection compared to existing methods. The developed sensor has potential applications in clinical diagnostics, particularly for real-time monitoring of metabolic conditions such as diabetes and ketogenic diets.
(Keynote) High Power Batteries Enabled by Disordered Rocksalt Anodes
Authors: Liu Ping
Published: December 2024

Batteries with exceptional charge and discharge rates and cycle life can bridge the gap between high-energy-density batteries and supercapacitors. In traditional lithium-ion batteries, the limiting electrode is usually the carbon anode. Fast charging, for example, leads to deposition of lithium metal which triggers life and safety issues. Oxide anodes with higher operating potentials have been considered, e.g., lithium titanium oxide, titanium niobium oxide, to name a few.

In recent years, we have been developing lithium vanadium oxide as an anode. Li3V2O5 (LVO) has a disordered rocksalt (DRS) structure. When 2 moles of lithium are inserted into this structure, the volume change is about 5.5%. The cubic structure, however, indicates that the linear change is only 1.8%. The material has an operating potential of 0.6 V vs Li/Li+, thus virtually eliminating the possibility of lithium plating. Lithium-ion cells pairing LVO with 4V oxide cathodes have demonstrated thousands of stable cycles and can be charged at a rate as high as 20C (Nature, 2020, 63). To further lower the potential (which translates to higher energy density for a cell), we have investigated the possibility of doping with Mg. Both theoretical and experimental evidence suggest that the DRS structure is preserved. More interestingly, we have found that the electrode potential can indeed be lowered while the fast charging and long life qualities are preserved.

We have further extended this DRS design principle to sodium ion systems. Insertion of sodium into V2O5 results in the formation of a DRS structure, analogous to the case of lithium. Na3V2O5 (NVO) is found to accept two mole of Na reversibly within the DRS structure. Pairing NVO with a sodium vanadium phosphate cathode forms a sodium ion all vanadium battery. This battery has shown exceptional rate capabilities during both charging and discharging, with great potential for applications in power conditioning systems and grid storage.