bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Hybridization of Molecular and Metallic/Semiconductor Materials for CO2 Catalytic Reduction
Authors: Robert Marc
Published: July 2021

Reduction of carbon dioxide has as main objective the production of useful organic compounds and fuels - renewable fuels - in which solar energy would be stored. Molecular catalysts can be employed to reach this goal. They may in particular provide excellent selectivity thanks to easy tuning of the electronic properties at the metal and of the ligand second and third coordination sphere. Hybridization of these catalysts with conductive or semi-conductive materials may lead to enhance stability and new catalytic properties. This approach bridges between homogeneous and heterogeneous, and it raises new fundamental questions that may further lead to breakthrough in CO2 reduction chemistry.

Our recent results in this area will be discussed. [1-5]

References

M. Wang, L. Chen, T-C. Lau, M. Robert, Angew. Chem. Int. Ed.
2018, 57, 7769-7773.

S. Ren, D. Joulie, D. Salvatore, K. Torbensen, M. Wang, M. Robert, C. Berlinguette, Science
2019, 365, 367-369.

E. Boutin, M. Wang, J. C. Lin, M. Mesnage, D. Mendoza, B. Lassalle-Kaiser, C. Hahn, T. F. Jaramillo, M. Robert, Angew. Chem. Int. Ed.
2019, 58, 16172-16176.

B. Ma, G. Chen, C. Fave, L. Chen, R. Kuriki, K. Maeda, O. Ishitani, T-C. Lau, J. Bonin, M. Robert, J. Am.
Chem. Soc.
2020, 142, 6188-6195

P. B. Pati, E. Boutin, R. Wang, S. Diring, S. Jobic, N. Barreau, F. Odobel, M. Robert, Nat. Commun.
2020, 11:3499.
(Invited) Innovative Olivine Cathodes for High-Voltage and High-Rate Lithium Batteries
Authors: Vezzu Keti , Pagot Gioele , Negro Enrico , Di Noto Vito
Published: July 2021

Lithium batteries (LiBs) are among the most promising systems that could address today’s strongly increasing needs for an efficient, compact and reversible electrochemical storage of energy [1]. Indeed, LiBs are characterized by a high specific capacity, a high efficiency, and a long lifespan [2]. Unfortunately, improvements in the working potential, in the specific energy, and in the rate capability properties of the cathodes are still needed to comply with the specifications required by practical applications.

This work describes the synthesis and the characterization of a new family of high-voltage and high-rate cathodes for LiBs. A high-performing olivine material of the type LiMPO4 (M = Fe, Ni, and Co) [3] has been modified by inserting into the structure high-valence transition metal ions (e.g., V(V), Nb(IV), and Ta(IV)) [4]. The effects of the insertion of the different ions on the structural, morphological, electrical and electrochemical properties of the materials have been thoroughly studied. The stoichiometry is evaluated by means of Inductively-Coupled Plasma Atomic Emission Spectroscopy (ICP-AES); the morphology and size distribution of the grains are characterized by Scanning Electron Microscopy (SEM) and High-Resolution Transmission Electron Microscopy (HR-TEM); the structure is examined by powder X-Ray Diffraction (XRD) as well as a variety of IR spectroscopy techniques. The electrochemical characterization is carried out by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), and charge/discharge tests at different current rates. Finally, the conductivity mechanism is studied by Broadband Electrical Spectroscopy (BES). The cathode materials described in this report exhibit a high performance in terms of working potential (4.0 ÷ 5.0 V vs. Li/Li+), specific capacity (149 mAh∙g-1), and specific energy (656 mWh∙g-1). Moreover, the insertion of high-valence transition metals results in an improvement of the rate capability of the cathodes, allowing for fast charge and discharge processes.

References

[1] V. Di Noto, T. A. Zawodzinski, A. M. Herring, G. A. Giffin, E. Negro, S. Lavina, Int. J. Hydrogen Energy 37 (2012) 6120-6131.

[2] B. Scrosati, J. Garche, J. Power Sources 195 (2010) 2419-2430.

[3] G. Pagot, F. Bertasi, G. Nawn, E. Negro, G. Carraro, D. Barreca, C. Maccato, S. Polizzi, V. Di Noto, Adv. Funct. Mater. 25 (2015) 4032-4037.

[4] G. Pagot, M. Bandiera, K. Vezzù, A. Migliori, R. Bertoncello, E. Negro, V. Morandi, V. Di Noto, Journal of Materials Chemistry A, doi: 10.1039/D0TA06865A
Multifunctional Nanostructured Metal Selenides for Non-Enzymatic Electrochemical Sensors: Dopamine and Glucose Detection
Authors: Singh Harish , Nath Manashi
Published: July 2021

Glucose and dopamine (DA) play essential physiological functions associated with disorders such as diabetes mellitus, Parkinson's disease and schizophrenia. For both analytical applications and diagnostic testing, accurate glucose and DA determination is essential. In this current work, efforts have been made to develop non-enzymatic direct electrochemical sensors for DA and glucose based on transition metal chalcogenides as electrocatalysts . The bifunctional sensors capable of detecting glucose and DA levels simultaneously is highly desirable because diabetes often changes dopaminergic function and alters dopamine-regulated activity. Among all the niche applications and properties of transition metal chalcogenides, recently these materials have gained attention due to their favorable electrochemical properties owing to tunable redox behavior of the transition metal center. Recently we have identified several binary metal selenides and tellurides compositions grown on different flexible substrates through electrodeposition, hydrothermal synthesis as well as by chemical vapor deposition which exhibits exceptional activity for DA detection and electrocatalytic glucose oxidation at low applied potential. Typically, copper selenide nanostructures were synthesized which could detect glucose and dopamine with high selectivity at different applied potentials. These sensors also showed enhanced sensing parameters including low limit of detection and high sensitivity (0.068 µM and 26 µA µM-1 cm-2 respectively, for copper selenide catalyst) for glucose and dopamine, respectively. The electrochemical studies shows long-term stability as well as sensitivity with a detection region from 5 nm to 2 μM of dopamine, rapid response time along with excellent reproducibility. Furthermore, for practical application, human blood serum was also tested for accurate detection of DA and glucose level. The results suggested that such nanostructured metal chalcogenides-based sensor may be a potential candidate for designing continuous monitoring devices for detection of DA and glucose in physiological environments with blood and other tissue fluids. In this talk we will present detailed study of transition metal chalcogenides as electrocatalysts for dopamine sensing and direct glucose oxidation along with an understanding of their structure-property relationship.
Electron Transfer Kinetics at Polysulfone-Copper Oxide Metalloplastic Nanocomposite Surface
Authors: Fakayode Olayemi Jola , Nkambule Thabo T.I.
Published: July 2021

The study evaluated the electrochemical charge transfer kinetics at two polysulfone-copper oxide polymeric semi-conducting nanocomposite electrode surfaces (compact and thin-film) in the presence of phosphate ions. The materials were characterized using scanning electron microscopy (SEM), energy dispersive x-ray (EDS) and cyclic voltammetry (CV). The results showed that both materials followed Laviron’s prediction of the diffusionless electrochemical process leading to variable estimation of transfer coefficients and rate constants. Furthermore, the rate of electron transfer at each surface varied with the scan rate while the thin-film electrode showed better anodic transfer rate than the compact electrode. Significantly, the materials showed the transition from the adsorbed species electrolysis to diffused species electrolysis in a vice versa manner when the change in the peak potentials was varied with the logarithm of the scan rates. Transfer coefficients between 0.8 and 1.0 and rate constants between 6.0 x 10-3 - 3.5 x 100 s-1 were obtained within the experimental conditions. The materials generally showed the capability to split hydrogen peroxide to oxygen gas at room temperature. The significance of the study on the application of the materials for various functions such as sensors and fuel cell fabrication was discussed.

Figure 1
Photo-Induced Signal Chains at Enzyme Electrodes
Authors: Riedel Marc , Lisdat Fred
Published: July 2021

During the last decade photoelectrochemical devices which couple biochemical reactions to light-sensitive electrodes have gained increasing research interest. These kind of light-triggered systems have the inherent advantage that an additional tool - the light - can be used to control the reactions at a sensing electrode. This allows a light-directed read-out, but can also be used to change the energetic situation on the surface resulting in advantageous potential behavior [1].

Enzymes as biocatalysts provide the advantage of a catalytic analyte conversion and specificity in this reaction. In order to couple them to light-sensitive electrodes different approaches have used.

Besides the use of co-substrates or products [2], we have been focusing on the use of mediators for this interaction [3] or the establishment of a direct electron transfer of the enzyme to the light- sensitive entity [4]. Here we report on the use of two different types of polymers for establishing the electrical contact.

In order to exploit the advantages of a high surface area we have constructed 3D electrodes which can be rather easily prepared by a template approach combined with spin coating as deposition method..Thus, the thickness of the electrode structure can be adjusted in a defined way [5,6].

In a first approach 3D TiO2 of inverse opal character has been sensitized by a conducting polymer – sulfonated polyaniline. The polymer has here two functions: It ensures the light sensitivity in the visible range and also provides an interface at which the enzyme can exchange electrons. Advantageously the current signal can be gained at rather low potential. Furthermore, the response can be tuned by the dimensions of the 3D electrode demonstrating the scalability of the approach.

As a further advancement we have used a redox polymer in order to couple FAD-dependent glucose dehydrogenase to the electrode. Here PbS QDs have been generated directly onto a 3D TiO2 electrode and characterized by TEM and photoelectrochemistry. The system allows the generation of a defined anodic photocurrent, which can be significantly enhanced by the biocatalytic conversion of glucose. Here the substrate dependent current signal starts at about -054V vs Ag/AgCl.

Such electrode systems can find application in light-triggered sensing, but also for bioenergetics since the photocatalytic process can be “feeded” by electrons from the biocatalytic conversion.

References

[1] F. Lisdat, D. Schäfer, A. Kapp, Anal. Bioanal. Chem. 405, 3739 (2013).

[2] J. Tanne, D. Schäfer, W. Khalid, W. J. Parak, F. Lisdat, Analytical Chemistry 83 (20) (2011) 7778–7785

[3] M. Riedel, N. Sabir, F. W. Scheller, W. J. Parak, F. Lisdat, Nanoscale 9, 2814 (2017).

[4] Ch. Stoll, S. Kudera, W.J. Parak, F. Lisdat,”,SMALL 2 (6) (2006) 741-743).

[5] M. Riedel, F. Lisdat, ACS Applied Materials & Interfaces, (2018), Vol. 10 (1), p. 267-277

[6] M. Riedel, W. Parak, A. Ruff, W. Schuhmann, F. Lisdat, ACS Catalysis, (2018), Vol. 8, 5212-5220
(Invited) An Insight into the Reaction Mechanism of Organics on Palladium-Based Electrocatalysts
Authors: da Silva Rodrigo Garcia , de Andrade Adalgisa Rodrigues , Servat Karine , Morais Claudia , Napporn Teko , Kokoh Boniface
Published: July 2021

Alcohols are promising renewable and sustainable fuel alternatives for low-power energy devices. As the number of carbons in this type of fuel increases, the power density decreases, but in parallel with the generated energy, the capacity of recovering value-added products in cogeneration increases as well 1,2. In this context ethylene glycol, glycerol and glucose were investigated on nickel and ruthenium modified palladium nanocatalysts with electrochemical, spectroelectrochemical, and chromatographic methods. These carbon-supported materials prepared by a revisited polyol approach coupled with microwave irradiation exhibited high activity towards the ethylene glycol electrooxidation in alkaline medium. Long-term electrolysis conducted in a batch three-electrode cell, coupled with High Performance Liquid Chromatography/Mass Spectrometry (HPLC-MS) and in situ Fourier Transform Infrared Spectroscopy (FTIRS) measurements permitted the determination and the identification of the compounds electrogenerated in the oxidative conversion of this two-carbon molecule. Addition of Ni to the Pd-based catalyst results in bimetallic compositions with a metal loading that changes away from the theoretical one as the Ni content increases. In terms of catalytic activity, the presence of Ni provides a strain effect at low content, giving way rather to a surface restructuring effect which predominates when the Ni content is raising (Ni50@Pd50/C). Molecules such as oxalate, glyoxylate, and glycolate were identified in all the electrolytic solutions, while glyoxylate was selectively formed at the Ru45@Pd55/C electrode surface. In situ FTIRS results also showed a decrease of the pH value in the thin layer near the electrode as a consequence of OH- consumption during the spectroelectrochemical experiments. The concentrations of the reaction products are slightly higher at the Ru45Pd55/C surface, where the electronic effect of Ru on the d-band center of Pd was clearly marked by the shift of the ethylene glycol oxidation towards the lower potentials. These results will serve as guidelines for future work related to potential applications of ethylene glycol in fuel cell devices, promoting cogeneration of high value-added products.

Acknowledgements: This work was mainly conducted in the framework of the collaborative program CAPES/COFECUB under grant n° 914/18. The authors also acknowledge the financial support from FAPESP (grants number 2013/25632-0), the European Union (ERDF), and EDF.

References

1. Y. Holade, K. Servat, T. W. Napporn, C. Morais, J.-M. Berjeaud, K. B. Kokoh, ChemSusChem, 9, 252 (2016).

2.Y. Holade; N. Tuleushova, S. Tingry, K. Servat, T. W. Napporn, H. Guesmi, D. Cornu, K. B. Kokoh, Catal. Sci. Technol., 10, 3071 (2020).
(Invited) Interfacial Free Charge Density Gradients in Room Temperature Ionic Liquids and Their Potential Applications
Authors: Wang Yufeng , Hossain Md. Iqbal , Blanchard Gary J
Published: July 2021

We have reported the existence of long range order (ca. 50 μm) in room temperature ionic liquids (IL) which is induced by the surface charge of the support on which a film of ionic liquid resides. This long range order can be modulated by the support surface charge, providing facile control over the sign and magnitude of the gradient with respect to the surface normal. The gradient is a free charge density gradient and our recent work has demonstrated a direct relationship between this gradient and induced birefringence in ILs. Our findings indicate that the chemical structure of the ionic liquid constituents play an important role in mediating the role of diluents in this class of materials, and that ILs do not form homogeneous solutions with dilutens, but rather exhibit microscopic structural heterogeneity. Both of these findings are not only of fundamental interest; they also provide opportunities for the application of ILs in areas such as electro-optic devices and in thin-film sensing applications.
Key Role for Nonlinear Phenomena of Li-O2 Batteries in Discharge Properties
Authors: Hase Yoko
Published: July 2021

Li-O2 batteries have attracted much attention as one of the candidates of future energy devices because of their ultimate energy density. This specific property of Li-O2 batteries is derived from the discharging reactions, which consist of the dissolution of Li metal of anode and oxygen reduction reaction (ORR) on the cathode.1-3 However, many issues to apply them for practical use, such as the limited capacity and low energy efficiency, have remained undissolved. In typical Li-O2 batteries, carbon materials are applied as cathodes on which the discharge product, Li2O2, forms and deposits. Due to the inherently low electron conductivity of Li2O2, deposition on the cathode prevents continuous discharge, and causes the cell voltage to drop sharply during constant current discharging. This nonlinear phenomenon, which is called “Sudden cell death”, is known to restrict the discharge capacity of Li-O2 batteries.

Herein, we present that the negative differential resistance (NDR), which appears in the ORR of Li-O2 batteries, plays a key role in the discharge properties.4-6 The existence of NDR in the potential region of discharge implies that LiO2, which is an intermediate of the discharge reaction, impedes the ORR and its coverage varies with the cell voltage. Since LiO2 is desorbed from the cathode at higher cell voltage than NDR region, ORR proceeds via “the solution pathway” where Li2O2 forms in the electrolyte is promoted. Meanwhile, the lower cell voltage leads “the surface pathway” in which the adsorbed LiO2 is further reduced to Li2O2 on the cathode surface. Therefore, these results rationally revealed that there is a transition of pathways from the solution to the surface in the galvanostatic discharging process, and this transition causes “Sudden cell death”. The cell voltage where the transition region of reaction pathways appears shifts with cathode materials and electrolytes, therefore, the design of appropriate condition of usage is important to induce the maximum performance of Li-O2 batteries.

References

1) A. C. Luntz, B. D. McCloskey, Chem. Rev.,
114, 11721-11750 (2014).

2) C. Shu, J. Wang, J. Long, H. K. Liu, S. X. Dou, Adv. Mater., 31, e1804587 (2019).

3) W. J. Kwak, Rosy, D. Sharon, C. Xia, H. Kim, L. R. Johnson, P. G. Bruce, L. F. Nazar, Y. K. Sun, A. A. Frimer, M. Noked, S. A. Freunberger, D. Aurbach, Chem. Rev., 120, 6626-6683 (2020).

4) Y. Hase, Y. Komori, T. Kusumoto, T. Harada, J. Seki, T. Shiga, K. Kamiya, S. Nakanishi, Nat. Commun., 10, 596 (2019).

5) K. Nishioka, K. Morimoto, T. Kusumoto, T. Harada, Y. Hase, K. Kamiya, S. Nakanishi, Chem. Lett., 48, 562-565 (2019).

6) Y. Hase, K. Nishioka, Y. Komori, T. Kusumoto, J. Seki, K. Kamiya, S. Nakanishi, J. Phys. Chem. Lett., 11, 7657-7663 (2020).
The Efficiency of the Electro-Oxidation of Small Organic Molecules: Oscillations and Mechanism
Authors: Varela Hamilton
Published: July 2021

Many hydrogen-carriers have been considered for the direct use in fuel cells and also in the electrochemical reform, where they are oxidized instead of water at lower potentials. We have investigated the electro-oxidation of formaldehyde, formic acid, methanol, and ethanol,[1] and of ethylene glycol, glycerol, and glucose[2] on polycrystalline platinum in acidic media, and compare the activity under conventional and oscillatory regimes. The comparison is carried out by different means and generalized by the use of simple identical experimental conditions in all cases. The activity along slow potentiodynamic curves, inferred by the peak current, decreases in the following sequence: formaldehyde ~ formic acid > methanol > ethanol ~ ethylene glycol > glucose > glycerol. The ubiquitous occurrence of potential oscillations under galvanostatic regime is associated with excursions of the electrode potentials to lower values, which noticeably decreases the overpotential of the anodic reaction, when compared to that in the absence of oscillations. Considerable enhancement in the power density was observed in an idealized fuel cell operated with those fuels when operated under oscillatory regime. Furthermore, the spontaneous periodic self-cleaning processes, present important advantages to the use of autonomous oscillations to reach both higher and long-term activities, and stability [3]. The discussion of these half-cell studies is complemented with experiments with proton exchange membrane fuel cells, namely direct liquid fuel cells (DLFCs). We have investigated the effect of temperature on DLFCs under conventional and oscillatory conditions.[4] Methanol, formic acid, ethanol, and dimethyl ether (DME) were used as fuels and identical experimental conditions were used in all cases. Some findings observed in half-cells are also observed in the DLFCs studied, but few peculiarities of the experimental configuration adopted in the later arise. Finally, mechanistic aspects underlying the observed dynamics are discussed.

[1] M. V. F. Delmonde, L. F. Sallum, N. Perini, E. R. Gonzalez, R. Schlögl, H. Varela, J. Phys. Chem. C
120 (2016) 22365.

[2] G. B. Melle, T. A. Ferreira, R. L. Romano, H. Varela, in preparation (2020).

[3] J. A. Nogueira, P. P. Lopes, N. M. Markovic, H. Varela, Electrochem. Commun.
121 (2020) 106853.

[4] J.A. Nogueira, H. Varela, Energy Fuels
34 (2020) 12995.
Spatiotemporal Patterns of Oscillatory Electrochemical Reactions in the Presence of a Low-Pass Filter
Authors: Ocampo Espindola Jorge Luis , Kiss Istvan Z.
Published: July 2021

In many electrochemical measurements, the measured signals are often filtered to remove experimental noise, for example, with a low-pass filter (LPF). At the same time, various electrical coupling (potential drop in the electrolyte) and feedback (galvanostatic constraints) effects can generate spatiotemporal patterns. In this contribution, we study the synchronization patterns of electrochemical oscillators induced by feedback in the presence of a low-pass filter. Close to a Hopf bifurcation, without the filter, as expected[1], the synchronization transition took place above a critical coupling strength following a second-order phase (Kuramoto) transition. With LPF, the transition occurred through explosive synchronization, which corresponds to a first-order phase transition and multistability between synchronized and desynchronized states. These experimental results confirm recent theoretical development on the impact of LPF on the synchronization of Stuart-Landau oscillators[2]. Further away from Hopf bifurcation, the LPF can generate patterns with one- and two-cluster states from a desynchronized state. The cluster formation and stability can be understood using a theory that estimates the LPF induced amplitude attenuation and phase shift of the coupling functions in the phase model of the oscillatory process. Our study points to the importance of using filtering in engineering synchronization states of oscillatory electrochemical reactions.

Kiss, I.Z., Y. Zhai, and J.L. Hudson, Emerging Coherence in a Population of Chemical Oscillators. Science, 2002. 296(5573): p. 1676.

Zou, W., M. Zhan, and J. Kurths, Phase transition to synchronization in generalized Kuramoto model with low-pass filter. Physical Review E, 2019. 100(1): p. 012209.
Asymmetry Induced Suppression of Chaos in an Electro-Chemo-Mechanical System
Authors: Biswas Animesh , Chaurasia Sudhanshu Shekhar , Parmananda Punit , Sinha Sudeshna
Published: July 2021

Multiple unconnected chaotic relaxation oscillators realized by an electro-chemo-mechanical system (Mercury Beating heart) is coupled to a markedly different common external chaotic system realized by an electronic circuit. Upon exploring the resultant dynamics, it is found that, for sufficiently strong coupling, oscillatory activity of the group of oscillators is quenched by a single dissimilar chaotic oscillator. The results are corroborated numerically using model relaxation oscillator systems mimicking the interaction through coupled ordinary differential equations. A completely distinct chaotic external system is able to quench the ensemble’s oscillations most efficiently rather than a regular external oscillator or a system identical to the ensemble. This control of a group of oscillators using a dissimilar external system points to a powerful control strategy which is experimentally demonstrable. The general principle of emergent symmetry from asymmetric constituent systems which is illustrated here suggests that diversity or heterogeneity is a crucial factor in interactive systems exhibiting regularity.
Stochastic Resonance Via Parametric Adaptation: Experiments and Numerics
Authors: Tiwari Ishant , Cruz José Manuel , Parmananda Punit , Rivera Marco
Published: July 2021

We present the observation of stochastic resonance (SR) in an electrochemical system while keeping the noise amplitude in the system fixed and varying the parametric distance from a homoclinic bifurcation inherent to the system. This is in contrast to the conventional method of observing SR at an optimal amplitude of noise while keeping the other system parameters constant. The system under study is the corrosion of a circular metal disk's surface in an acidic medium under potentiostatic condtions. Applied potential is the system's bifurcation parameter while the anodic current from the electrodissolution of the metal is the system observable. The system exhibits enhanced fidelity with a weak subthreshold input signal in the presence of noise and at an optimal parametric distance from the bifurcation. The observed results are corroborated using a numerical model for this system. SR using this protocol maybe a possible mechanism a biological entity can exploit when it has no control on the environmental noise amplitude but can control its own sensory parameters.
(Invited) Probing the Electronic Structure of Oxide Electrocatalysts and the Formation of Reaction Intermediates
Authors: Stoerzinger Kelsey A
Published: July 2021

Perovskite oxides (ABO3) are highly active for the oxygen evolution reaction (OER). Activity is observed to correlate with changes in bulk electronic structure parameters, such as metal-oxygen covalency and transition metal oxidation state. We employ spectroscopic approaches to consider such descriptors at the surface of perovskite oxides in situ, as well as their implications on the formation of surface adsorbates proposed to act as reaction intermediates during the OER.

Many surface science techniques, such as X-ray photoelectron spectroscopy (XPS), collect information from inherently surface-sensitive low-energy processes, requiring operation in ultrahigh vacuum. This constraint is lifted for ambient pressure XPS, which can probe the surface in equilibrium with the gas phase at pressures up to ~a few Torr, or with thin liquid layers using a higher incident photon energy. This presentation will discuss the insights obtained with this technique regarding the electronic structure of oxide electrocatalysts in an oxidizing or humid environment, as well as the reaction intermediates of relevance to electrocatalysis.1 We will then extend the technique to probe electrocatalysts in operando,2 driving current through a thin layer of liquid electrolyte and employing a tender X-ray source.

References:

[1] Stoerzinger,K.A.Wang, L. Ye, Y. Bowden, M. Crumlin, E.J. Du, Y. Chambers, S.A. “Linking surface chemistry to photovoltage in Sr-substituted LaFeO3 for water oxidation”. Journal of Materials Chemistry A 6 (2018) 22170-22178.

[2] Stoerzinger, K.A. Wang, X.R. Hwang, J. Rao, R.R Hong, W.T Rouleau, C.M. Lee, D. Yu, Y. Crumlin, E.J. Shao-Horn, Y. “Speciation and electronic structure of La1-xSrxCoO3-δ during oxygen electrolysis”. Topics in Catalysis 61 (2018) 2161–2174.
Cu(II) Metal-Organic Framework Based Electrochemical Sensor for Methanol Quantification in Alkaline Media
Authors: Cruz-Navarro Jesús Antonio , Mendoza Huizar L. Humberto , Salazar Pereda Veronica , Cobos Murcia José Angel , Álvarez Romero Giaan Arturo
Published: July 2021

Metal-Organic frameworks are novel materials with specific pore-size that presents unlimited applications in electrocatalysis and electro-analytical chemistry. The presence of metallic ions in the MOF structure offers a redox active material with electrocatalytical properties in alkaline media towards diverse organic compounds and heavy metals. This property is extensively used to replace enzymes in electrochemical sensors for detecting glucose and other molecules. In this work, we present the synthesis, characterization and application of Cu-BTC MOF as redox active material in a carbon paste electrode (CPE) for methanol electrochemical sensing in alkaline media. The obtained electrode was evaluated for the selective quantification of methanol in ethanol solutions by using diferential pulse voltammetry. The analysis of methanol with the modified electrode presented a LOD, LOQ and sensitivity of 0.04438 mM, 0.1479 mM and 52.74 ± 1.3 μA mM-1 respectively, and a electro-active area of 0.01723 cm2. Our analytical parameters are superior compared with those presented by using enzyme-based electrodes. These results demonstrate the potential use of Cu-BTC@EPC sensors in detecting MeOH at low concentratios, even in presence of ethanol.

Figure 1
Uncovering Phase Transformation, Morphological Evolution, and Nanoscale Color Heterogeneity in Tungsten Oxide Electrochromic Materials
Authors: Hu Anyang , McGuigan Scott , Lin Feng
Published: July 2021

The electrode–electrolyte interfacial chemistry determines the durability of electrochromic devices. The long‐term cycling stability of transition metal (TM) oxide electrochromic films in the acidic electrolyte is impoverished, which is a major obstacle towards deep market penetration through sustainable and cost-effective smart windows. The research interest in nanostructuring TM oxide films to improve electrochromic performance has grown rapidly. However, there are few fundamental studies that investigate the mechanism of electrochromic degradation. In this work, we revisit the classical tungsten trioxide (WO3) materials as the platform to uncover the previously unknown interrelationship between morphological evolution, phase transformation, nanoscale color heterogeneity, and durability in these electrochromic materials. Through synchrotron spectroscopic, microscopic, and imaging characterizations, we experimentally reveal that tungsten dissolution/redeposition and proton-trapping are the two fundamental origins for performance degradation. The WO3–electrolyte interface is reshaped due to the metal dissolution and redeposition during electrochemical cycling. The recurrent redeposition process provokes the in situ crystal growth, which ultimately leads to the phase transformation from the semicrystalline WO3 to a nanoflake-shaped, proton-trapped tungsten trioxide dihydrate (H
x
WO3·2H2O). Besides, the heterogeneous proton trapping during long-term electrochemical cycling brings about the charge heterogeneity of thin-film electrodes, which further creates a significant degree of nanoscale color heterogeneity. The interaction between phase transformation, morphological evolution, and nanoscale color heterogeneity results in degraded cycling durability, including inferior optical modulation, switching kinetics, coulombic efficiency, and bleached-state transparency. Our work highlights that the high interfacial reactivity near the electrode surface may be the underlying mechanism for undesired bulk structural changes of electrochromic materials. The overwhelming morphological changes reported here may raise concerns about the legitimacy of a large body of literature that attributes the electrochromic performance solely to initial nanostructure design. More fundamental studies are needed to probe and control the interfacial chemistry in electrochromic and other electrochemical devices.
Oxygen Evolution Reaction Enables Better Performance for Aqueous Na-Ion Batteries
Authors: Zhang Yuxin , Lin Feng
Published: July 2021

Aqueous batteries have attracted intensive attention owing to their inflammable water-based electrolyte. However, the upper cut-off voltage is significantly limited by the oxygen evolution reaction (OER) induced by water decomposition, which undermines the energy density of most aqueous batteries. OER not only consumes electrolytes but also leads to severe side reactions between generated oxygen and electrodes, resulting in rapid capacity decay. One of the most important aspects in maintaining a long aqueous battery lifetime is to suppress oxygen gas generation or eliminate oxygen gas in the cell. Although the negative effects of OER are well accepted, the positive influence is still ambiguous. In this presentation, we will discuss how properly manipulating OER can serve as an approach to improving the performance of aqueous batteries.

Na-deficient Prussian Blue (PB) cathodes are undesired for aqueous full-cells due to the insufficient amount of cyclable Na-ions and inferior specific capacity. Our study will demonstrate that the performance of Na-deficient PB cathodes based full cells can be improved by OER. Relying on the two-electrode glassware cell composed of Na-poor PB cathode and NaTi2(PO4)3 (NTP) anode, the bubble generation on the cathode was directly observed during overcharging process, confirming the occurrence of OER at high charging states. After the overcharging protocol was applied to the coin cell during the first cycle, the discharge capacity was elevated from 55 mAh/g, which originates from low Na content in the pristine cathodes, to 130 mAh/g. Further analysis on structural evolution and charge compensation mechanisms revealed that, accompanying the OER on the cathode, Na ions in the electrolyte get inserted into the NTP anode during overcharging process, resulting in more cyclable Na-ions in the full cell system and thus enhancing the discharge capacity. On the other hand, owing to the pH gradient on the cathode surface caused by water decomposition, transition metal dissolution was reported through X-ray fluorescence mapping, leading to the declined Coulombic efficiency. Our study illustrates the potential utilization of overcharging protocol and offers fundamental insights into the influence of oxygen evolution reaction in aqueous batteries.
Exploring Iron Oxides Anodes By Tuning Their Structure and Morphology for Lithium-Ion Batteries
Authors: Hagerman Tanner Gardell , Ketelsleger Cameron , Gregory Darrell , Walters Keisha , Abbott Brandon , Capraz Omer Ozgur Özgür
Published: July 2021

Demand for lithium-ion batteries is increasing with the increase in portal electronic, electric vehicle and renewable energy. High energy dense electrode materials are required to meet this demand. In this study we are exploring an alternative anode material to graphite electrodes. We chose Iron Oxides due their abundancy and high capacity1 .

We altered the structure and morphology of iron oxide nanoparticles (IONP) and prepared electrodes from the following nanoparticles (NP): Commercial iron (III) oxide NP (Fe2O3), iron oxide NP + succinic acid, iron oxide NP + citric acid, silica-encapsulated Fe3O4 NP and iron oxide NP + perchloric acid. Slurries were made using a conductive carbon (Super P) carboxymethyl cellulose and ultra-pure water in a weight ratio of 8:1:1 (w/w). Lithium perchlorate (1 M) was dissolved in ethylene carbonate and dimethyl carbonate and used as the electrolyte. Using an ARBIN battery test unit, cyclic voltammetry was performed between 0.05 and 3.0 V and compared to a lithium counter electrode at a scan rate of 0.1 mV/s. Figure 1 compares the electrochemical performance of these iron oxide anodes with different structure and morphology.

This was supported by Oklahoma State University’s CEAT undergraduate research scholarship.

[1] Wang, X. et al (2016). Uniform Fe3O4 microflowers hierarchical structures assembled with porous nanoplates as superior anode materials for lithium-ion batteries. Elsevier Applied Surface Science vol (389) 240-246. Doi: 10.1016/j.apsusc.2016.07.105

Figure 1
Analysis of Iron (III) Perchlorate at Magnetically Modified Electrodes
Authors: Dadallagei Kasun Saweendra Rathnatunga , Leddy Johna
Published: July 2021

Electrochemical reactions drive many chemical processes using well established protocols and hardware. Most improvements of electrochemical reactions require substantial changes to existing protocols and equipment, However, our previous work has shown that electrochemical systems may be impacted by the presence of magnetic field gradients at the electrode surface. Using ion exchange polymer films with embedded magnetic microparticles, it is possible to improve reaction kinetics. Previous cyclic voltammetric studies of metal tris-bipyridine complexes at electrodes modified with composite films of Nafion and magnetized microparticles exhibit substantially higher currents than at electrodes modified with simple Nafion films.

The aim of this study is to show magnetic field gradients can enhance currents for redox probes other than metal tris-bipyridine complexes and to use methods alternative to cyclic voltammetry (CV). Iron (III) perchlorate is the first transition metal species evaluated by impedance to exhibit enhanced electron transfer rates at electrodes modified with magnetized microparticles in Nafion. The enhancement is attributed to improvements in kinetics of heterogeneous exchange rate and self exchange rate.

Electrochemical impedance spectroscopy (EIS) and CV studies at magnetically modified electrodes are compared to non-magnetic analogs for the iron (III) perchlorate redox couple. This redox couple shows kinetic rate enhancements for the magnetically modified electrodes over the non-magnetic analogs.
(General Student Poster Session Winner - 1st Place) An Algorithm for Fitting Tafel Data and Determining Kinetic Parameters
Authors: Coduto Joshua Richard , Leddy Johna
Published: July 2021

Tafel analysis is widely used to characterize electrochemical kinetics and assess the properties of electrocatalysts for use in fuel cells, electrolyzers, and other applications. Conventional Tafel analysis is an extension of the Butler-Volmer equation at high overpotentials under conditions where mass transport is not significant and the reverse reaction rate is negligible compared to the studied half-reaction. Determination of kinetic parameters from a Tafel plot involves linear regression in regions of large overpotential. This method is limited in part by the subjective determination of linearity, as the kinetic parameters obtained by the regression may vary significantly depending on the chosen linear region.

In an effort to increase measurement quality and decrease subjectivity, an algorithm has been developed that generates a Tafel plot from a linear sweep voltammogram (LSV) and determines the exchange current density j
0, charge transfer coefficient α, and Tafel slope of closest fit. Comparisons of kinetic parameters between conventional and algorithmic Tafel analysis are made for the hydrogen evolution reaction (HER, 2H+ + 2e- → H2) on different metal electrodes and Nafion® composite electrodes. The algorithmic Tafel analysis parameters correlate well with conventional methods. Similar agreement is observed between literature and algorithmically fitted kinetic parameters for different electrochemical systems. The developed algorithm allows for straightforward, rapid, and user bias independent Tafel analysis and can be easily used to increase measurement quality.
Inactivation of Human Coronavirus (SARS-CoV-2) By Titania Nanoparticle Coatings and UVC Radiation
Authors: Khaiboullina Svetlana , Uppal Timsy , Dhabarde Nikhil , Subramanian Vaidyanathan , Verma Subhash
Published: July 2021

The novel pathogenic human coronavirus, SARS-CoV-2, led to an atypical pneumonia-like severe acute respiratory syndrome (SARS) outbreak called coronavirus disease 2019 (abbreviated as COVID-19). Nearly, 77 million cases have been confirmed worldwide with the highest COVID-19 cases been confirmed in the United States. Substantial efforts to create a potential vaccine to combat COVID-19 are underway. In the meantime, safety precautions and effective disease control strategies appear to be vital for preventing the virus spread in the public places. Due to the longevity of the virus on smooth surfaces, photocatalytic properties of “self-disinfecting/cleaning” surfaces appear to be a promising tool to help guide disinfection policies to control infectious SAR-CoV-2 spread in high-traffic areas such as hospitals, grocery stores, airports, schools, and stadiums. The photocatalytic properties of nanosized TiO2 (TNPs) as induced by the UV radiation, towards virus deactivation have been explored in this study. The preliminary results using close genetic relative of SAR-CoV-2, HCoV-NL63, showed the virucidal efficacy of photoactive TNPs deposited on glass coverslips, as examined by quantitative RT-qPCR and virus culture assays. The photocatalytic inactivation performance of TNPs was evaluated under different light intensities, humidic conditions, and UV-exposure time. The findings form the basis for the application of an electrical bias on the TiO2 electrodes towards removal and inactivation of the virus. Efforts to extrapolate the underlying concepts described in this study to SARS-CoV-2 are currently underway.
Thermo-Electrochemical-Mechanics Interactions on Thermal Safety in Li-Ion Cells
Authors: Parmananda Mukul , Zhou Hanwei , Vishnugopi Bairav Sabarish , Mukherjee Partha P.
Published: July 2021

The thermal safety of lithium-ion batteries poses a serious concern towards using high power and energy-dense batteries for electric vehicles. The lithium-ion battery performance in a pouch cell format is greatly influenced by heterogeneity at different scales that translate to localized over-potentials, heat generation, plating severity, and mechanical stress. Such localized thermo-electrochemical-mechanics interactions can arise due to microstructural variability at mesoscale and cell architecture-induced heterogeneity (tab design) at a macro-scale. We use a microstructure resolved macro-scale (pouch cell) model to develop a fundamental understanding of the influence of heterogeneity on cell performance in terms of localized temperature rise, plating severity, and accelerated degradation under operational extremes. Finally, the effect of thermo-electrochemical interactions on localized lithium deposition is coupled to a thermal abuse model. The modeling capability elucidates the impact of plating heterogeneity on thermal runaway dynamics within a pouch cell operated under thermal abuse conditions.
Underpotential Lithium Plating on Graphite Anodes Caused by Temperature Heterogeneity
Authors: WANG Hansen , Cui Yi
Published: July 2021

Rechargeability and operational safety of commercial lithium (Li)-ion batteries demand further improvement. Plating of metallic Li on graphite anodes is a critical reason for Li-ion battery capacity decay and short circuit. It is generally believed that Li plating is caused by the slow kinetics of graphite intercalation, but in this paper, we demonstrate that thermodynamics also serves a crucial role. We show that a non-uniform temperature distribution within the battery can make local plating of Li above 0 V vs. Li0/Li+ (room temperature) thermodynamically favorable. This phenomenon is caused by temperature dependent shifts of the equilibrium potential of Li0/Li+. Supported by simulation results, we confirm the likelihood of this failure mechanism during commercial Li-ion battery operation, including both slow and fast charging conditions. This work furthers the understanding of non-uniform Li plating and will inspire future studies to prolong the cycling lifetime of Li-ion batteries.
Characterizing Materials and Electrochemical Changes in a Range of 18650 Li-Ion Cells Cycled to 80% Initial Capacity
Authors: Wittman Reed M , Dubarry Matthieu , Ivanov Sergei , Fresquez Armando , Langendorf Jill , Grant Richard , Taggart Gretchen , Chalamala Babu , Preger Yuliya
Published: July 2021

Understanding systematic trends in degradation of Li-ion batteries through a broad range of operating conditions is critical to improving their performance. Over the course of the last few years, researchers at Sandia National Labs have been conducting a systematic study of battery cycling behavior. In this study, dozens of commercial NCA (LiNixCoyAl1-x-yO2) and NMC (LiNixMnyCo1-x-yO2) cells were cycled to 80% capacity across a range of temperatures, discharge rates, and depth of discharge windows. Analysis of both in situ electrochemical data and postmortem materials degradation was done and correlated to determine root causes of rapid capacity fade.

During cycling, Electrochemical Impedance Spectroscopy (EIS) and Incremental Capacity Analysis (ICA) experiments were conducted periodically. The data from these experiments were used to understand the state of health (SoH) of cycling cells, including SEI formation and Li plating, as well as general mass transport and kinetic properties.

X-ray Computed Tomography (XCT) scans completed before cell disassembly showed large scale deformation in the cells’ jelly rolls. For the postmortem analysis, cells in pristine condition and 80% capacity were disassembled, and their electrodes were analyzed with X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC). These techniques analyzed different aspects of the electrodes’ physical and chemical properties, including Li plating, micro-cracking, SEI layer formation, and phase changes in cathode materials. DSC measurements also provided insight into changes in the degree to which aged electrodes undergo thermal runaway events.

Correlation of the postmortem materials analysis with the in situ electrochemical analysis showed that cells with the most rapid rate of capacity fade had multiple degradation mechanisms active during cycling. The scale of this electrochemical and materials evaluation fills in gaps in the literature about commercial Li-ion battery performance.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Developing Wearables for Neuropeptides and Neurotransmitters Detection in Sweat Using Flexible Substrates
Authors: Vázquez Antonio , Rivera Vitmary , Acosta Lina , Santiago Arianna , Cunci Lisandro
Published: July 2021

In the last decade the field of research in biosensors has had a great interest in the development and manufacture of sensors capable of detecting and monitoring analytes in body fluids such as sweat, tears, and saliva. This interest arises since the traditional method for monitoring a large majority of analytes related to diseases or health conditions is carried out through blood analysis. However, analysis of analytes in blood is a painful method, it is invasive sampling, and more expensive compared to sweat analysis. In recent years, a variety of wearables have been developed for the analysis of analytes in sweat, through electrochemical and optical interfaces. However, the problem with the development of these sweat biosensors has been limited to monitoring a small number of biomarkers such as lactate, glucose, electrolytes, and pH. Here, we present a biosensor for the detection and monitoring of Neuropeptide Y in sweat using flexible materials and different types of working electrodes. Neuropeptide Y has an important role in the energy balance and is related to different diseases and conditions such as diabetes, obesity, depression, anxiety, sleep problems, and a relationship of neuropeptide Y and heart attacks has also been found.