bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Mapping Electrochemical Strain in Platinum Nanoparticles Via Bragg Coherent Diffraction Imaging
Authors: Atlan Clément , Richard Marie-Ingrid , Martens Isaac , Dupraz Maxime , Chatelier Corentin , Viola Arnaud , Leake Steven , Maillard Frederic
Published: July 2022

Variations in the interatomic distances lead to altered d-band centre for a given metal, and provide an elegant way to control its activity towards (electro)catalytic reactions (“strain-engineering” approach). The effect of strain was rationalized within the frame of the d-band theory of Hammer and Nørskov in the late 1990s [1,2]. The authors predicted that the rate of the sluggish oxygen reduction reaction (ORR) can be enhanced on catalysts binding *OH ca. 0.10 - 0.15 eV more weakly than Pt(111), [1, 2] and this prediction was experimentally verified using a Pt3Ni(111)-skin surface.[3] Nevertheless, these predictions hardly translated to nanomaterials, because of the wide variety of catalytic sites configurations. Also, the d-band theory mostly considers catalytic surfaces in vacuum, without any effect related to the electrical double layer and adsorption/desorption processes. Hence, an in situ picture of how strain develops on Pt-based surfaces is still lacking.

In this contribution, we took benefit of recent advances in Bragg Coherent Diffraction Imaging (BCDI) [4, 5]and of the fourth generation Extremely Brilliant Source of the European Synchrotron (ESRF-EBS, Grenoble, France) to map strain over Pt nanoparticles in situ. Our results show that adsorption of anions causes appearance of compressive strain at under-coordinated (edges and corners) atoms and tensile strain at highly-coordinated ({001} and {111} facets) atoms. Strain heterogeneity increases with the electrode potential and reaches as large as 0.08 %. at ORR-relevant potential. These results provide direct insights into the dynamics of Pt nanoparticles in an electrochemical environment, and have direct consequences for electrocatalysis in general, and for ORR electrocatalysis in particular.

Ackowledgements

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant n° 818823). FM acknowledges the financial support from the French National Research Agency in the frame of the BRIDGE project (grant n° ANR-19-ENER-0008-01).

References

[1] B. Hammer, J. K. Nørskov, Surf. Sci. 1995, 343, 211.

[2] B. Hammer, Y. Morikawa, J. K. Nørskov, Phys. Rev. Lett. 1996, 76, 2141.

[3] V. R. Stamenkovic, B. Fowler, B. S. Mun, G. Wang, P. N. Ross, C. A. Lucas, N. M. Markovic, Science 2007, 315, 493.

[4] I. Robinson, R. Harder, Nat.
Mater. 2009, 8, 291.

[5] J. Carnis, A. R. Kshirsagar, L. Wu, M. Dupraz, S. Labat, M. Texier, L. Favre, L. Gao, F. E. Oropeza, N. Gazit, E. Almog, A. Campos, J.-S. Micha, E. J. M. Hensen, S. J. Leake, T. U. Schülli, E. Rabkin, O. Thomas, R. Poloni, J. P. Hofmann, M.-I. Richard, Nat.
Commun. 2021, 12, 5385.

Figure 1. Schematic representation of observed strain distribution over a Pt nanoparticle in 0.05 M H2SO4.

Figure 1
Anion Influenced Hydride Formation on Cu(111) during Electrocatalysis
Authors: Raciti David , Tackett Brian , Hight Walker Angela , Moffat Thomas P
Published: July 2022

In aqueous systems several environmentally relevant proton-coupled electron transfer reactions such as the reduction of O2, NO3, CO or CO2 are known to proceed on Cu surfaces in combination with proton and/or water reduction. Among these, the electrochemical reduction of CO2 receives the most attention because of Cu’s unique ability to produce varying degrees of hydrogenated multicarbon products. Despite intense experimental and theoretical studies, understanding of Cu’s facet specific selectivity is still limited especially regarding the role of H in hydrogenation steps. Using operando electrochemical mass spectrometry (ECMS) and shell-isolated nanoparticle enhanced Raman spectroscopy (SHINERS) this work identifies the existence of surface hydride on Cu(111) (Figure 1a) under conditions relevant for the aforementioned reduction reactions. The identified surface hydride is significantly impacted to changes in electrolyte composition, such as the cation, anion or dissolved gas species and likely has significant impact over electrocatalytic performance. ECMS plots (Figure 1b) of hydride formation and decomposition show that the stronger the binding affinity of the anion to the Cu(111) surface the larger the overpotential required for hydride formation (e.g. Cl- vs ClO4
-). Likewise, decomposition occurs at more negative potentials. Peak areas of respective vibrational modes (Figure 1 c-d) corroborate the ECMS data, also demonstrating that in the presence of Cl- (vs SO4
2-) both hydride formation and decomposition shifts negatively by nearly 100 mV. These dynamics among other more quantitative analysis of hydride coverage and kinetics will be presented within this talk.

Figure 1
(Keynote) Insights into the CO2 Reduction Pathway through the Electrolysis of Aldehydes
Authors: Marx Melissa A , Cui Zhihao , Cho Sung Gu , Charnay Benjamin P , Co Anne C.
Published: July 2022

Investigating the electrochemical reduction of aldehydes to alcohols provides insights into the mechanistic pathways of converting CO2 to alcohols electrochemically. Both acetaldehyde and propionaldehyde were electrochemically reduced on a polycrystalline Cu catalyst to illustrate that it is a viable pathway to ethanol and 1-propanol, respectively, supporting the mechanistic route previously proposed in the literature. 13C and 1H NMR analysis on isotopically labeled acetaldehyde was utilized to trace the reduction process. In an aqueous solution, acetaldehyde is at equilibrium with ethanediol, and propionaldehyde with propanediol. The dissociation of adsorbed ethanediol to acetaldehyde and water was also found to be favorable on both Cu and Au surfaces. Experimental observations were also supported with DFT calculations, indicating a higher-energy reaction intermediate on Au (111) over Cu (100). In summary, the results from this study support previously proposed mechanisms and provide a framework for testing other stable CO2 reaction intermediates to gain insights into the overall CO2 reaction pathway.

Figure 1
Identity, Positioning, and Tunability of the Second Coordination Sphere in Molecular CO2 Reduction Electrocatalysis
Authors: Nichols Eva
Published: July 2022

Electrochemical reduction of carbon dioxide represents an attractive possibility for valorization of this abundant carbon feedstock while simultaneously removing it from the atmosphere. Enzymes that fix carbon dioxide feature precisely positioned amino acid residues in the secondary coordination sphere in order to modulate reaction energetics. This precedent motivates the design of molecular catalysts with rationally tunable functional groups in the second coordination sphere, which allow for a better understanding of the role of the local chemical environment. Here, we present recent studies on the synthesis and electrochemical behavior of molecular CO2 reduction catalysts and the importance of identity, positioning, and tunability of the second coordination sphere in modifying activity.
Understanding CO2 Electrolysis Reactionmechanisms Via pH and Isotopic Labeling Studies
Authors: Seger Brian , Deng Wanyu , Gong Jinlong
Published: July 2022

CO2 electrolysis is a highly useful technique allowing us to upconvert society’s major greenhouse gas into a variety of useful chemicals. However, mechanistically the process is still not totally understood both in 2 electron reduction products (e.g. CO) and in >2e- reduced products (e.g. ethanol/ethylene). This work will discuss using pH variations and deuterium to gain further insight into these mechanisms.

One area of debate for 2 electron transfer reduction products such as CO and formate is whether the rate limiting step involves a proton, a water molecule, or is simply due to adsorption of the CO2 onto the surface. This work will show the benefits of using deuterated water to help resolve this mechanism. By focusing on catalysts geared towards 2 electron transfer reactions to either formate or CO, we have a simple system to break down the mechanism into the reaction order in terms of protons and water molecules. Variations in pH from 3-7 allows us to show the influence of protons for CO or formate, with H2 evolution on a given catalysts acting as a benchmark. Using deuterated water allows us to denote the influence of water, again using H2 evolution as a benchmark catalyst. Combining both these influences we can mechanistically break down the reactions to denote the mechanism of the rate limiting step. (Since we have obtained relatively straight Tafel slopes over 3 orders of magnitude in current, this entails mass transfer is not significantly influencing our results.)

From our results we show that Au and Ag produce a self-consistent mechanism for CO2 to CO reduction, whereas Sn and In produce a self-consistent mechanism for formate evolution. Pd is unique in that it has the ability to solvate hydrogen and deuterium, thus the combined pH variations and deuterium demonstrates how this effect influences our mechanistic understanding.

For greater than 2 electron transfer processes (using Cu) two of the major issues are determining the rate limiting step and the branching point between ethanol and ethylene. We will show how variations in pH and using deuterated water can give insight into both of the aforementioned issues.
Mapping the Double Layer Using Proton-Coupled Electron Transfer at Functionalized Carbon Electrodes
Authors: Owhoso Fiki V , Kwabi David G.
Published: July 2022

Conductive electrodes functionalized with molecularly well-defined species are emerging as effective active materials for a wide range of applications, from electrocatalytic CO2 and O2 reduction, to high performance lithium-sulfur batteries.1–3 For redox-active species that participate in proton-coupled electron transfer (PCET), the extent of conjugation, applied potential, and distance between the redox center and electrode determine the potential and electric field experienced at the site of electron transfer. This electric field in turn determines the pH-dependent energetics of electron transfer (i.e. Pourbaix behavior) and the rate PCET. We discuss how measurements of PCET to redox-active species functionalized to carbon electrodes can yield insight into the potential and electric field profiles within the electrode-electrolyte double layer. Systematically increasing the distance between the redox-active moiety and the electrode results in the moiety experiencing a progressively weaker electric field, as determined by changes to PCET behavior. Based on these results, we propose strategies to quantify the strength of the electric field as a function of this distance. This work can inform strategies for effective pH modulation at electrified interfaces in ways that can enhance electrocatalytic processes and other applications, such as electrochemical CO2 capture based on pH swing.

References

Ren, G. et al. Porous Core-Shell Fe3C Embedded N-doped Carbon Nanofibers as an Effective Electrocatalysts for Oxygen Reduction Reaction. ACS Applied Materials and Interfaces
8, 4118–4125 (2016).

Zhang, S., Fan, Q., Xia, R. & Meyer, T. J. CO2 Reduction: From Homogeneous to Heterogeneous Electrocatalysis. Accounts of Chemical Research
53, 255–264 (2020).

Zhao, C.-X. et al. Semi-Immobilized Molecular Electrocatalysts for High-Performance Lithium–Sulfur Batteries. Journal of the American Chemical Society
143, 19865–19872 (2021).
(Digital Presentation) Stochastic Impact Electrochemistry in a Lateral-Flow Sensor Architecture
Authors: Weiß Lennart Jakob Konstantin , Lubins Georg , Music Emir , Rinklin Philipp , Peng Hu , Terkan Korkut , Mayer Dirk , Wolfrum Bernhard
Published: July 2022

During the recent SARS-CoV-2 pandemic, lateral flow assays (LFAs) have written an indescribable story of success, as they provide means for decentralized, low-cost, and easy-to-use testing. However, LFAs in their most common form support only qualitative results and their sensitivity and limit of detection is significantly limited by the colorimetric readout method. In contrast, single-impact electrochemistry offers the possibility to quantify species beyond picomolar concentrations by recording individual species collisions with a biased microelectrode. Within this work, we investigate the integration of stochastic sensing into a LFA-architecture by combining a wax-patterned microchannel with a microelectrode array in order to detect silver nanoparticles by their oxidative dissolution. Here, we demonstrate the possibility to resolve individual nanoparticle collisions in a paper-based microchannel using a simplified reference-on-chip setup. Furthermore, we simulated a lateral-flow sensor, by flushing previously dried silver nanoparticles towards the electrode array, where the particles are subsequently detected. This proof-of-principle illustrates that single-impact electrochemistry might be a promising technique to extend the capability of LFAs. Especially, the integration of functionalized nanoparticle labels could enable the rapid and on-site detection of very dilute species with exceptional sensitivity.
Using Dynamic Impedance Spectroscopy to Deconvolute Memory Elements in Droplet Interface Bilayers
Authors: Sacci Robert L , Scott Haden L , Liu Zening , Bolmatov Dimitry , Doughty Benjamin , Collier C. Patrick , Katsaras John
Published: July 2022

The underlying principles for generating and storing memory in living organisms differ significantly from traditional hard-matter-based circuits. Bio-inspired membranes are ideal platforms for exploring biomimetic neuromorphic equivalents as they offer novel forms of tunable plasticity and diverse mechanisms to control functionality. Droplet interface bilayers (DIBs) are inherently nanostructures that show electrical properties that are extremely sensitive to nano-scale perturbation. We will demonstrate how dynamic electrochemical impedance spectroscopy (dEIS) can follow molecular-level restructuring in DIBs that lead to hysteretic loops and mem-behaviors in lipid bilayers in response to electrical biasing. We deconvoluted the DIB system’s memristance and memcapacitance by measuring the time-dependent complex impedance to show that if the bilayer’s structure (thickness or area) changes, these quantities contain the same information; however, if a phase transition occurs, then these responses have additional information. Figure 1, demonstrates both the DIBs platform two major modes of voltage-inducing physical change that can occur in bilayers. Through correlation analysis of the capacitance/resistance, we show that memory processes caused by lipid bilayer expansion, or contraction, do not affect the observed electrical charge/discharge time constant. However, phase transitions resulting in new solvation or lipid structures affect the extracted electrical time constant. In short, dEIS coupled with time-constant analysis provides a means for extracting individual memory elements from a simple two-terminal device, thereby multiplexing the function and potential computational throughput.

Figure 1
Visualizing the 2nd Layer: 4,4´-Bipyridine Adsorption on Sb(111) from EMImBF4
Authors: Ers Heigo , Siinor Liis , Pikma Piret
Published: July 2022

Room temperature ionic liquids (RTIL) have had a lot of attention in modern chemical research. Due to their high stability under applied electrode potential, the wide electrochemical window and dual usability as a solvent and an electrolyte RTILs have become very attractive in the field of applied electrochemistry and modern energetics [1]. Molecular self-assembly at solid surfaces, resulting in the formation of the nanostructures with well-controlled properties and functionality reveals fascinating perspectives in science and technology at nanoscale [2]. For instance, the smart tailoring of the structural properties of the functionalized electrodes enables SAMs to be used as protective coatings and for the fabrication of organic thin-film transistors and sensors, and as triggers of specific electrochemical processes.

In this study the in situ STM and impedance spectroscopy methods have been applied to study the structure and properties of the electrochemically polished Sb(111) single crystal electrode | EMImBF4, and EMImBF4 + 1% 4,4´-bipyridine, interface.

Using in situ scanning tunnelling microscopy, the adsorption/desorption of 4,4’-bipyridine was demonstrated and a dense underlying structure, formed below a sparse self-assembled monolayer, was visualized. The detection of two separate adsorbed layers indicates that the ordering of organic molecules could extend well beyond the monolayer on the electrode’s surface. These insights are of fundamental and practical importance in the development of nanoelectronics.

References:

[1] H. Ohno (Ed.), Electrochemical Aspects of Ionic Liquids, John Wiley & Sons, Inc., New Jersey, 2005, p.1.

[2] T. Wandlowski, Phase Transitions in Two-dimensional Adlayers at Electrode Surfaces: Thermodynamics, Kinetics, and Structural Aspects, A.J. Bard, M. Stratmann (Eds.), Encyclopedia of Electrochemistry, Wiley VCH, Weinheim (2002) p. 383-471.

Acknowledgments:

This work was supported by the Estonian Research Council grant PSG249 and by the EU through the European Regional Development Fund under project TK141 (2014-2020.4.01.15-0011). For providing us with the computational resources, we would like to acknowledge the HPC Center of the University of Tartu.
Determination of Cr(VI) in Natural and Waste Waters Using Differential Pulse Polarography According to U.S. Epa (SW-846 Method 7198)
Authors: Vyas Ritesh Navneetrai , Brankle Dane , Howell Jon
Published: July 2022

The accurate determination of hexavalent chromium in environmental matrices such as natural and waste waters is crucial for the safety of both human and wildlife populations. The United States Environmental Protection Agency (U.S.EPA) has put forth SW-846, Method 7198, using differential pulse polarography for determination of Cr (VI) in both, the natural as well as waste waters. In Method 7198, the cathodic peak current resulting from the reduction of Cr (VI) to Cr (III) is measured and the concentration range for this method is listed as 10 ppb to 5 ppm Cr (VI). Using BASi Epsilon potentiostat that is specifically made for measuring ultra-low current resolutions and a controlled growth mercury electrode (CGME) set-up, the US EPA method 7198 has been successfully optimized in this work for higher detection limits. It is observed that a detection limit of up to 7 ppb can be easily obtained by efficiently managing the interference of iron and sulphur through a combination of various supporting electrolytes. This work may also become a valuable source of reference information on the behavior of wide variety of electrolytes and their control parameters needed to achieve extremely low detection limits.

Figure 1
(Digital Presentation) Amperometric Gas Sensor with Porous Electrodes Manufactured Via Laser Ablation
Authors: Struk Daniel , Paik Seung-Joon , Shafer Richard H. , Hesketh Peter J. , Patel Vinay , Peaslee David , Findlay Melvin , Stetter Joseph R.
Published: July 2022

Hydrogen sulfide, Nitrogen Dioxide, and sulfur dioxide are highly toxic gases with health effects at ppb and ppm levels in air. These compounds occur in industrial operations as well as in environmental atmospheric polluted air. Traditionally, microfabricated electrochemical gas sensors use photolithography processes for patterning of the electrodes and defining the electrode geometry for high surface area to increase the sensor gas sensitivity. We present herein a series of gas sensor designs fabricated via laser ablation of sputtered Au films. For these sensors, the laser ablation step itself takes less than two hours to pattern up to 60 sensors.

The sensors are fabricated on a porous hydrophobic substrate made of layers of a Teflon woven mesh, and the 400 nm gold film was sputtered onto a 100 nm tungsten adhesion layer. A total of 60 sensors was patterned in a 6 by 10 grid per substrate with each sensor having a footprint of 15 mm x 15 mm. An image of some of the sensors and their corresponding designs are illustrated in figure 1.

Laser ablation was performed by an Optec WS-Flex USP femtosecond 1030 nm laser. The pulse frequency was set to 400 kHz and both the speed and jump speed were set to 200 mm/s. The laser power is nominally 4 W and the power percentage setting was determined for each substrate by patterning a test array onto the substrate in increments of 2%. From this test array, the lowest power that completely ablated the gold could be determined and that was used for the remaining sensor ablation. Images of the etched surface area shown in the figure 1. Surface analysis with EDS using SEM microscope indicated the composition of the layers and effective removal of the gold from the Teflon sheet without damage to the Teflon porosity in the woven mesh, figure 2.

The sensor electrodes were assembled by lamination between several plastic layers and then an electrolyte was added. The assembled sensors were diced from the assembled 10x6 sensor wafer and individual sensors were connected to a potentiostat and tested via exposure to the various pollutant gases. The current response of these amperometric sensors was measured and found to be linear with respect to concentration in the low ppm range. This work illustrates an alternative to photolithography for the preparation of thin film gas porous electrodes for use in amperometric gas sensors.

Figure 1
Flexible Nonenzymatic Electrochemical Sensor for the Analysis of Urea in Artificial Sweat
Authors: Yoon Jaesik , Sim Myeongseok , Lee Doohee , Cha Yoolim , Wu Guodong , Kim Wonhyeong , Oh Tae-Sik , Yoon Young Soo , Kim Dong-Joo
Published: July 2022

Recently, wearable and flexible electrochemical sensors have attracted tremendous attention due to health monitoring and diagnostics for humans [1]. Such wearable devices will be able to provide low-cost, easy-to-use, and mass production for in-situ detection or point-of-care applications. Urea is an essential biomarker for the diagnosis of healthy kidneys because urea, a protein metabolite, is formed by the function of kidneys and is excreted into the urine. An abnormal concentration of urea can indicate potential kidney dysfunction. Although most urea sensors are based on the enzyme, the electrochemical sensors to use the nonenzymatic urea oxidation can provide higher stability, biocompatibility, and nontoxicity if nonenzymatic urea sensors address the hurdles such as high conductivity, a narrow range of urea reactions, and limited catalytic activities [2-4]. In addition, a sweat-based urea sensor may show good anti-interference performances for urea detection as the urea concentration in the sweat is 3.6 times higher than that of serum [5].

Herein, we report a sensitive and selective nonenzymatic urea sensor [6]. Flexible and wearable platforms were fabricated using electrospinning polystyrene (PS) containing carbon nanotube as a conductive component. For nonenzymatic catalysts, Ni-Cu alloys were co-sputtered on the PS substrate and transformed to a Ni-Cu oxyhydroxide form by cyclic voltammetry treatment. Such an electrode structure with porous PS is believed to provide sufficient active sites, easy access to reactants, and adequate water wettability for effective charge transfer. The fabricated sensor presented an excellent linear response of 2.00-30.00 mM with a high sensitivity of 10.72 μAmM–1 cm–2 and 4.67 μM LoD for urea detection in neutral pH solution and artificial sweat. The dynamic bending test via 200 times and up to 150° angle bending showed excellent mechanical tolerance where bending deformation of the sensor platform does not affect electrochemical performance.

References

Bariya, Mallika, et al. “Wearable sweat sensors.” Nature Electronics 1, 160-171 (2018).

Debata, Suryakanti, et al. "Design of CdV2O4-V6O13 micro flowers for non-enzymatic electrochemical detection of urea." In AIP Conference Proceedings, vol. 2115, no. 1, p. 030058. AIP Publishing LLC (2019).

Yoon, Jaesik, et al. “Silver-Nanoparticle-Decorated NiOOH Nanorods for Electrocatalytic Urea Sensing.” ACS Applied Nano Materials 3, 7651-7658 (2020).

Yoon, Jaesik, et al. “Ag/ZnO Catalysts with Different ZnO Nanostructures for Non‐enzymatic Detection of Urea.” Electroanalysis 31, 17-21 (2019).

Thudichum, J. L. W. "On the analysis of urea in urine for clinical purposes." British medical journal 1, 38, 788 (1857).

Yoon, Jaesik, et al. “Flexible Electrochemical Sensor Based on NiCu(OOH) for Monitoring Urea in Human Sweat.” Journal of Electrochemical Society 168, 117510 (2021).
A Novel Electrochemical DNA Sensor Based on Redox Modulated Fluorescence Intensity
Authors: Ma Tianxiao , Ma Tianxiao
Published: July 2022

In clinical applications, a highly sensitive and specific biosensor is required for detecting the trace amount of genetic analyte1. There have been numerous techniques developed for improving the sensitivity and selectivity of the DNA biosensor. Many PCR-based techniques including gene sequencing and fluorescence quantitative polymerase chain reaction have shown advantages such as high accuracy and sensitivity2. However, these techniques are complicated to use and require professionally trained personal. On the other hand, electrochemistry-based measurements such as Square-wave Voltammetry and Cyclic Voltammetry usually assume the electron transfer kinetics of the redox-active monolayer assemblies are uniform. The signal generated is an average and the detailed information about the modified surface is difficult to obtain. Here we show a novel detection method using electrochemistry coupled with fluorescence microscopy. A mixed SAM composed of Methylene Blue (MB) or AlexaFluor488 (AF488) labeled single stranded DNA were electro-deposited on a single crystal gold bead electrode3. We observed a unique profile of fluorescence signal (AF488) modulated by the redox probe (MB) upon DNA hybridization events. In addition, we have found that different surface crystallographies exhibit different sensitivities to the complementary strand (e.g. target) which can be explained by differences in surface coverages4. We demonstrate a coupled electrochemical and fluorescence DNA sensor.

References:

Pheeney, C. G.; Barton, J. K. DNA Electrochemistry with Tethered Methylene Blue. Langmuir
2012, 28(17), 7063–7070.

Santhanam, M.; Algov, I.; Alfonta, L. DNA/RNA Electrochemical Biosensing Devices a Future Replacement of PCR Methods for a Fast Epidemic Containment. Sensors (Switzerland)
2020, 20 (16), 1–15.

Ma, T.; Bizzotto, D. Improved Thermal Stability and Homogeneity of Low Probe Density DNA SAMs Using Potential-Assisted Thiol-Exchange Assembly Methods. Chem.
2021. 93 (48), 15973–15981.

Mirmomtaz, E.; M. Castronovo.; L. Casalis. Quantitative study of the effect of coverage on the hybridization efficiency of surface- bound DNA nanostructures. Nano Lett. 2008, 8 (12), 4134–4139.

Figure 1
Synthesis of Pt Nanoparticles Encapsulated inside Dendrimers As Tunable Oxidase Mimics for Turn-on Fluorescent Sensing of Oxygen
Authors: Kim Joohoon , Lee Hyein , Cho Taehoon
Published: July 2022

Here, we present the controllable synthesis of dendrimer-encapsulated Pt nanoparticles (Pt DENs) utilizing repetitively coupled chemical reduction and galvanic exchange reactions. This facile method allowed controllable synthesis of the Pt DENs with fair homogeneity in size and composition. In particular, in contrast to the conventional dendrimer-templating methods, the proposed synthesis method allowed substantial increase in the applicable number of Pt atoms up to 1320 in Pt DENs without being limited by the fixed number of complexation sites for the Pt2+ precursor ions in dendrimers. We also present a detailed investigation on the oxidase-mimetic activity of the Pt DENs for catalytic oxidation of Amplex Red to resorufin with O2. Importantly, after clarifying intrinsic oxidase-mimetic activity of the Pt DENs, we disclosed that the Pt DENs’ oxidase-mimetic activity was tailorable for the oxidation of Amplex Red to resorufin especially with fine-tuning of the Pt2+/dendrimer ratios by using the proposed synthesis method.
(Invited) Rare-Earth-Based Nanoparticles As Multimodal Bioprobes
Authors: Hemmer Eva
Published: July 2022

The remarkable optomagnetic properties of the rare-earths (RE) make RE-based materials ideal for biomedical applications, including diagnostic (e.g., imaging, nanothermometry) and therapeutic (e.g., drug delivery, photodynamic therapy) approaches. This is due the unique electronic properties of the f-elements allowing for upconversion and near-infrared emission under near-infrared excitation as well as high magnetic moments.

Yet, challenges remain; low emission intensity and efficiency of small nanoparticles (NPs), and reliable, fast synthesis routes. As material chemists, we tackle these challenges with new designs of RE-NPs by chemically controlled synthesis, application-oriented surface chemistry, and understanding of structure-property-relationships. Sodium rare-earth fluorides (NaREF4) are our favorite materials, and we developed a fast and reliable microwave-assisted synthesis approach allowing crystalline phase and size control in the sub 15nm realm. Such control is crucial for the understanding of fundamental structure-property relationships and to optimize their optical and magnetic properties, when aiming for the design of next-generation optical probes or contrast agents for magnetic resonance imaging. For instance, NaGdF4 NPs are gaining interest as alternative MRI contrast agent, while co-doping with RE3+ ions renders them excellent candidates for photoluminescent optical probes. The hexagonal crystalline phase of NaGdF4 is known as the more efficient host material for upconversion emission, yet interestingly, it was found that its cubic counterpart shows superior performance as MRI contrast agent. Having a fast and reliable synthesis route towards NaREF4 NPs on hand, we now explore various nanoparticle architectures and compositions with the goal to optimize their optomagnetic properties, ultimately resulting in the design of biocompatible multimodal bioprobes.

This presentation will shed light on recent results and remaining challenges in the field of RE-based nanostructures with respect to their microwave-assisted synthesis as well as structural and optomagnetic properties, seeking biomedical application, while also touching on hyperspectral imaging as an emerging analytical tool offering spatio-spectral information about RE-based materials.
(Invited) Designed DNA Nano-Switches As Sensitive Electrochemical Biosensors
Authors: Yu Hogan (Hua-Zhong)
Published: July 2022

Functional nucleic acid receptors (aptamers) have emerged as effective and robust recognition elements for state-of-the-art biosensors. Analytical readouts from aptamer-based biosensors (whether optical, electrochemical, or otherwise) derive primarily from global-scale conformational changes induced in the aptamer domain by analyte binding. Herein, we describe a unique biosensor design principle that represents a distinct alternative to this paradigm; particularly we demonstrate the ready applicability of this design principle in the de novo creation of electrochemical sensors for a clinical analyte of current interest. The function of the class of biosensors we describe, termed “DNA nano-switches”, is designed to depend on the integrity of duplex DNA-mediated charge transfer between an electrode and a redox label.

[1] Thomas, J. M.; Chakraborty, B.; Sen, D.; Yu, H.-Z. J. Am. Chem. Soc.
2012, 134, 13823–13833.

[2] Tang, Y.; Ge, B.; Sen, D.; Yu, H.-Z. Chem. Soc. Rev.
2014, 43, 518–529

[3] Ma, F.; Qi, L.; Einarson, O.; Sen, D.; Yu, H.-Z. Anal. Chem.
2019, 91, 8244−8251.

Figure 1
Development of Heteroarene-Fused Quinones As Rapidly Dissoluble and Stable Biosensors
Authors: Lee Woohyeong , Joo Jung Min , Nandhakumar Ponnusamy , Nam Sangwook , Bhatia Aman , Seo Jia , Kim Gyeongho , Yang Haesik
Published: July 2022

Aqueous electron mediators for point-of-care testing require a variety of properties, such as rapid dissolubility, high stability, and moderate formal potential (near 0 V). Using the redox-active properties of quinone derivatives, various quinone-containing electron mediators have been developed for electrochemical sensors. However, most quinone derivatives exhibit very low solubility in aqueous solutions and instability in the presence of nucleophilic species. Herein, we report a strategic design for quinones incorporating sulfonated thioether and nitrogen-containing heteroarene moieties as solubilizing, stabilizing, and formal potential-modulating groups. Systematic investigations found that di(thioether sulfonate)-substituted quinoline-1,4-dione (QLS) and quinoxaline-1,4-dione (QXS) displayed high water solubility and rapid dissolubility. By finely balancing the electron-donating effect of the thioethers and the electron-withdrawing effect of the nitrogen atom, formal potentials suitable for electrochemical biosensors are achieved with QLS and QXS (−0.15 and −0.09 V vs Ag/AgCl, respectively, at pH 7.4). QLS is stable for >1 d in PBS (pH 7.4) and for 1 h in tris buffer (pH 9.0), which is sufficient for point-of-care testing. Furthermore, QLS, with its high electron mediation ability, is successfully used in biosensors for sensitive detection of glucose and parathyroid hormone. This strategy provides organic electron mediators that exhibit rapid dissolution and high stability and will find broad applications beyond quinone-based biosensors.

Figure 1
Enzyme-Free Glucose Monitoring Patch
Authors: Yeasmin Sanjida , Wu Bo , Ullah Ahasan , Zhang Xueqiao , Cheng Li-Jing
Published: July 2022

Monitoring of glucose levels in non-invasive biofluids, such as saliva and sweat, can advance personal health tracking. However, the approach remains challenging due to the low glucose concentration in saliva and sweat, about 100 times lower than in the blood. Commercial glucose sensors rely on glucose oxidase to measure blood glucose levels with enzyme reactions. The enzyme activity varies with pH, oxygen level, and temperature (more than 40ºC). Also, the method often suffers from cross-reactivity with other sugar molecules, such as maltose and xylose [1]. Thus, it is crucial to develop highly sensitive and stable non-enzymatic sensors for detecting glucose in non-invasive biological fluids.

In this work, we present an enzyme-free, reagent-free electrochemical glucose monitoring patch based on a glucose imprinted polymer nanocomposite. The nanocomposite comprises redox-active chitosan-ferrocene (Cs-Fc) wrapped multi-walled carbon nanotubes (MWCNTs). The Cs-Fc is a polymer with covalently secured redox-active ferrocene, effectively preventing the out leakage of redox substances [2]. The incorporation of MWCNTs increases the surface area, conductivity, and electron transfer rate. The glucose imprinted layer was grown on the surface of the nanocomposite by electropolymerization of functional monomers o-phenylenediamine (o-PD) and 3-aminophenylboronic acid (APBA) in the presence of glucose templates. The successful removal of template molecules created glucose speciﬁc recognition sites in the polymer matrices. The sensor directly detected the presence of glucose upon their binding into these cavities. The electrochemical property of the modified sensor was characterized by cyclic voltammetry (CV) in a potential range of 0-0.5 V at a scan rate of 100 mVs-1 in 1x PBS (pH 7.4) solution. For glucose sensing, the sensor was immersed in a sample solution containing different glucose concentrations for 30 min. We have optimized the composition ratio and assay conditions for sensitive glucose detection. Preliminary results indicated a change in redox peak current of ~2.7 times relative to the control upon adding 1 mM glucose, as shown in Figure 1. The proposed glucose patch is label-free, reagentless, cost-effective, easy fabrication, and expected to be utilized for sensitive and selective glucose detection from sweat.

References

[1] Hwang, D.W., Lee, S., Seo, M. and Chung, T.D., 2018. Recent advances in electrochemical non-enzymatic glucose sensors–a review. Analytica chimica acta, 1033, pp.1-34.

[2] Wu, B., Yeasmin, S., Liu, Y., and Cheng, L.J., 2022. Sensitive and selective electrochemical sensor for serotonin detection based on ferrocene-gold nanoparticles decorated multiwall carbon nanotubes. Sensors and Actuators B: Chemical, 354, p.131216.

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(Digital Presentation) Sol-Gel Based Synthesis Route for High Capacity Disordered Rocksalt (DRX) Oxyfluoride Cathodes
Authors: Patil Shripad , Self Ethan , Nanda Jagjit
Published: July 2022

The cost and energy density of commercial Li-ion batteries (LIBs) are largely limited by the cathode. Currently, the LIB cathode market is dominated by intercalation type layered transition metal oxides of the general form LiNixMnyCo1-x-yO2 (NMC). As the LIB market continues to grow, there is an increasing risk of over-reliance on cobalt and nickel, which not only leads to increased cost and resource depletion, but also raises ethical concerns related to the cobalt mining industry. Hence, there is an urgent need to develop new cathodes based on earth abundant materials.

Disordered rocksalt (DRX) oxides and oxyfluorides have emerged as a promising candidate for next generation LIB cathodes due to their high energy density and ability to utilize low-cost, earth abundant elements such as Mn and Ti. Studies have shown that anionic substitution of oxygen with fluorine enhances electrochemical performance and cycling stability of DRX cathodes. DRX cathodes are traditionally synthesized using high temperature solid-state and high energy mechanochemical routes. While these methods have yielded promising cathodes, they face challenges with fluorine substitution and process scalability. Keeping this in mind, the goal of this research is to develop alternate synthesis routes to prepare DRX oxyfluoride cathodes and identify key structure – property correlations to optimize cathode performance. Our team recently developed a sol-gel based approach to synthesize Li1.2MnxTi0.8-xO2-yFy (y=0-0.2; x=0.4-0.6) DRX oxides and oxyfluorides. This presentation will discuss recent development related to the synthesis, structure, and performance of these cathodes

Acknowledgements

This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) and is sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) through the Vehicle Technologies Office (VTO).
A Thermo-Electrochemical Model for Simulating Internal Short Circuits in a Li-Ion Battery Depending on Lithium Dendrites
Authors: Kim Suhwan , Song Jihun , Lee Hyobin , Jung Seungwon , Park Joonam , Lee Yong Min
Published: July 2022

An internal short circuit (ISC) is known to be the main cause of fatal accidents in Li-ion batteries (LIBs). If two electrodes come into contact with each other because of any event, the inner temperature of LIBs increases rapidly within the very short time. If the temperature can increase over the threshold temperature, fire or explosion accidents can occur in the LIB, which is called thermal runaway (TR). Because the fire in the LIBs is not easily extinguished and can cause significant damage of life and property, we should understand the fundamental electrochemical and thermal behavior of ISC-TR in order to prevent or delay these severe accidents. For this purpose, there have been tremendous attempts to analyze different ISC cases with a variety of LIB cells experimentally through penetrating nails, pucks, shape memory alloys, etc. However, experimental methods have limitations in measuring internal temperatures and estimating current density and lithium-ion concentration within LIB cells. Also it is still challenging to control the types and locations of ISCs practically. To compensate these experimental limitations, many simulation studies have also been conducted. However, many simulation research have been considering a two-dimensional-based microscale domain, which may have relatively inaccurate simulation results or cannot consider three-dimensional placement, or a three-dimensional-based large domain, which calculates ISC only in mm units or more.

In this work, we developed an advanced thermo-electrical model to simulate the responses of LIB cells depending on the sizes, numbers, and locations of lithium dendrites or impurities. This model can calculate the current density, which causes joule heat flux, and simulate heat transfer. Thus, this model can provide us with information on what kinds or how many of lithium dendrites will lead to thermal runaway. Also, it is possible to analyze the thermal behavior of LIBs according to the various physical and temperature conditions of the lithium dendrites.
(Digital Presentation) Cold Plasma-Enhanced N-Doped Carbon Coating over MOF Endorsed Metal Oxide Nano Seed Embedded Carbon Fabric for Ultra-Long Life Flexible Energy Storage Application
Authors: Bhattarai Roshan Mangal , Saud Shirjana , Mok Young Sun
Published: July 2022

The deformable electronic devices such as flexible, foldable, bendable, wearable, etc., are deemed the future of portable electronics, which could only be realized through the proper design of an energy storage unit that could power them. Herein, we report the conception of an ultrastable, binderless flexible electrode/substrate configuration that can be implemented in various energy storage applications such as supercapacitors, lithium-ion batteries, sodium-ion batteries, lithium-sulfur batteries, and alike. Firstly, the conductive carbon fabric was electrochemically deposited with nickel nanospheres; then the ZIF-67 metal-organic framework (MOF) promoted metal hydroxide nanostructures were grown over the Ni-CCF substrate. As grown nanostructures were then embedded inside the CCF through a meticulous optimization process varying the calcination temperature and gas concentrations. The metal seed embedded CCF was then coated with the hydrocarbons, the precursors of which are generally known volatile organic compounds and pollutants such as C2H4, CH4, CO2, and NH3 through the dielectric barrier discharge (DBD) plasma at atmospheric pressure and temperature. The carbonization of the final product results in the ultra-robust flexible electrode with metal-oxide nano seeds embedded CCF, coated with ~20nm nitrogen-doped carbon thin film which will be an excellent electrode material for an ultra-long life flexible energy storage system.

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Atomistic Scale Analysis of Motion and Dynamics of Li-Ion in Li-Zn-Zr-S Compound Electrolyte
Authors: Kwon Eunji , Lim Hyun-kyu , Lee Sangheon
Published: July 2022

Solid-state electrolytes are considered as key materials for overcoming the limitations of the liquid-electrolyte-based Li-ion batteries in terms of energy capacity, cyclability, and safety. Among the many possible solid-state electrolyte materials, inorganic sulfides are of intensive research interest mainly because the larger and more polarizable sulfur anions substantially enhance the mobility of cationic Li species. In particular, Li-P-S electrolytes, such as Li10GeP2S12and Li7P3S11, have been reported to have room-temperature Li-ion conductivity of greater than 10-2 S/cm, which is comparable to that of conventional liquid electrolytes. Despite the facile Li-ion transport, the Li-P-S electrolytes tend to undergo irreversible structural degradation within typical operating conditions of the battery. This lack of electrochemical stability leads to the formation of high impedance intermediate transition layers at the electrode/electrolyte interfaces, hindering the practical application of the Li-P-S electrolytes. Partial replacement of the element P with other elements within a Li-P-S structural family can improve the lithium-ion conductivity, but notable improvement in their electrochemical stability has yet to be achieved. Li-M-S (M = transition metals, such as Cr, Zr, Nb, Mo, and Sn) families can be possible candidates for electrochemically stabile solid-state electrolytes, while having excellent Li-ion transport properties of the inorganic sulfides. Like the Li-P-S structure, numerous Li-M-S structural derivatives have already been synthesized by varying the element M or by replacing a portion of the element M with another element, and the Li-ion conductivity and electrochemical stability are expected to be heavily dependent on the element composition and crystalline structure.

In this study, we investigate the motion and dynamics of Li-ions in Li-Zr-S and Li-Zn-Zr-S compound electrolyte by performing a series of first-principles calculations. To this end, we generate multiple Li-Zn-Zr-S compound model structures with varying Zr-to-Zn ratios. Then, we evaluate Li-ion conductivities by using velocity auto correlation scheme combined ab initio molecular dynamics (AIMD) simulations. More specifically, we calculate the diffusivity and ionic conductivity of the stoichiometric structure and at a range of defect concentrations on Li2+2xZnxZr1-xS3, from x = 0 to x = 0.5. Our calculation results reveal how the introduction of Zn into the Li-Zr-S compound affects the Li-ion mobilities. The theoretical insight obtained in this study well corroborates with recently reported experimental results for varying ionic conductivities in Li-Zn-Zr-S electrolytes depending on the Zr-to-Zn ratio. This fundamental understanding can be an important theoretical basis for developing practically applicable Li-M-S electrolytes.

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Concentration Profile Measurements Near the Anode during Lithium Metal Dissolution in Highly Concentrated Electrolyte
Authors: Kamesui Go , Nishikawa Kei , Matsushima Hisayoshi , Ueda Mikito
Published: July 2022

In recent years, highly concentrated electrolytes (HCEs) have been attracting attention as electrolytes for next-generation batteries. Lithium metal is used as an anode in next-generation batteries such as lithium-sulfur batteries, and it is important to clarify the deposition and dissolution mechanisms in HCEs. In this study, the concentration profile near the anode and the coordination state surrounding lithium ions were in-situ measured by a laser interferometer and Raman spectroscopy during lithium dissolution in the Sulfolane-based HCE.
(Digital Presentation) Effects of Cation Doping on the Stability and Charge Acceptance of Alpha Nickel Hydroxide for Energy Storage Applications
Authors: Ilhan Turan , Göynük Tansu , Karakaya Ishak
Published: July 2022

Nickel hydroxide is used as active material in nickel based batteries and capacitors. It has two phases which are alpha and beta, since alpha nickel hydroxide has higher capacity it attracts scientists attention. Although it has promising performance, low utilization and poor stability hinder commercialization of alpha nickel hydroxide. The most common strategy to improve stability is to dope nickel hydroxide with cobalt or aluminum. Aluminum is more prominent due to its lower price and environmental concern. Besides the stability, it is well known that discharge capacity of nickel hydroxide decreases with increasing amount of both aluminum and cobalt. Although capacity is decrasing, number of electrons which is involved in the reaction does not change with increasing amount of dopant. At the same molar doping levels, although aluminum doped samples had higher active mass (nickel) content, they had lower gravimetric capacity than cobalt doped samples. Therefore, it is not convenient to explain capacity loss by only decreasing amount of active mass.

Since cobalt doping raises differences between oxygen evolution potential and oxidation potential of nickel hydroxide, it enhances chargeability of nickel hydroxide but the cyclic voltammetry results showed that higher cobalt doping causes decrease in cell voltage and energy density of battery. The results showed that higher amount of aluminum must be doped to improve stability and relatively small amount of cobalt must be used to improve chargeability of alpha nickel hydroxide. Therefore, both aluminum and cobalt are effective in improving stability but cobalt is advantageous at low doping level, as it is reported in the literature.