bluuebunny/crossref_metadata_2025 huggingface dataset:
Graphite Recovery in Spent Lithium-Ion Batteries
Authors: Yao Zeyi , Wang Yan
Published: September 2023

Due to their high specific energy density (Wh/kg), high volumetric energy density (Wh/L), and long cycle life, lithium-ion batteries (LIBs) are being widely used. With the rapid growth of demands on LIBs these years, recycling methods are developed to solve the shortages of supply for rare metal cathode materials, especially Li and Co. However, not being evaluated as high-value material, graphite in spent LIBs always gets neglected and is burnt or downcycled which consequently generates CO2 gas as an inescapable result. Recent reports show the market demand for energy storage from Li-ion batteries will reach 400 GWh in the year 2022, which required nearly 3 million tons of graphite, also it is estimated that 3 billion batteries are thrown away each year in America. Considering the raw material making graphite is organic materials from nature with an irreversible process, a vicious circle can’t be broken if graphite doesn’t get recycled. Remarkably, our group has developed a novel closed-loop hydrometallurgical process for recycling end-of-life Li-ion batteries. After developing acid leaching and alkaline sintering methods, recycled graphite with an ultra-high purity (over 99.99%) is obtained for the first time in the hydrometallurgical process. Being successfully scaled up to the industrial level, it’s proved to be a green and high-efficient method in battery recycling. Further economical and efficient modification means are followed, recovering the structure, and improving the stability of recycled graphite to approach the commercial standard. In summary, our research provides a novel maneuver to fully purify and recover recycled graphite, which has great potential to be commercialized.
Direct Recycling of End-of-Life Lithium-Ion Battery Cathode Materials through Redox Mediator Chemistry
Authors: Kirwa Cyrus Kibichi , Coyle Jaclyn , Luo Hongmei
Published: September 2023

The surge of electric vehicle (EVs) adoption means imminent large amounts of lithium-ion battery waste will be generated. The need for recycled Li-ion batteries (LIBs) material is crucial for the sustainability of the renewable energy industry. The recycling process needs to be both economically and environmentally conscious. The 3 recycling methods being used today are pyrometallurgical, hydrometallurgical, and direct recycling. Pyrometallurgy is an expensive and energy-intensive process due to high energy requirements to reduce the End-Of-Life (EOL) Cathode materials. The component metal oxides are reduced to an alloy of Cobalt, Nickel, Manganese, Copper, and Aluminum. The hydrometallurgy process involves the use of aqueous solutions to leach the desired metals from EOL materials. This process is still expensive and has a considerable amount of waste generated from sintering, acid leaching, and chemical precipitation. Direct recycling on the other hand is cheaper and generates the least amounts of waste. Redox chemistry mechanism method for direct recycling is explored in this work to relithiate EOL NMC622 cathode material. Quinone-based redox mediators are used to restore lithium content in the EOL material. The redox mediator is reduced in the reaction and EOL is oxidized. These compounds can shuttle the charges very fast between lithium metal and the EOL. Analysis and characterization of the relithiated EOL NMC622 cathode material are carried out to compare with pristine baseline NMC622 cathode material. This approach will potentially pave way for quality material recovery at a low cost. This project is part of ReCell which is a collaborative effort to develop efficient and economical recycle and reuse methods for EOL battery cathodes.

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Probing Reaction Heterogeneity in Thick Electrodes: LiFePO4 Versus LiNi0.6Mn0.2Co0.2O2
Authors: Li Zeyuan , Wang Fan , Gao Yuan , Yang Yang , Meyer Matthew , Ai Qing , Tang Ming
Published: September 2023

Introducing thick electrodes is a sound practice for increasing the energy density of lithium-ion batteries by minimizing the ratio of inactive components at device level. However, the inferior rate performance of the thick electrodes, which is believed to be caused by the inhomogeneous reaction, limits their further applications. In this study, we investigate the reaction distribution in LiFePO4 and LiNi0.6Mn0.2Co0.2O2 thick electrodes with combined scanning X-ray fluorescence (XRF) microscopy and X-ray absorption near edge structure (XANES) spectroscopy. 2D XRF-XANES imaging shows discharge reaction is highly non-uniform in the LFP electrode’s depth direction, the degree of which increases with the discharge rate. In contrast, NMC retains a uniform SOC distribution up to 1C (or 1.5C) rate. The XRF-XANES observations are verified by ToF-SIMS measurements. The different reaction distributions observed in LFP and NMC is explained by P2D modeling and has a thermodynamic origin

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Development of Stable All-Solid-State Sodium-Sulfur Batteries
Authors: Jhang LI-JI , Wang Daiwei , Silver Alexander , Li Xiaolin , Reed David , Wang Donghai
Published: September 2023

Sodium-sulfur (Na-S) batteries have been commercialized for stationary energy storage systems because of their low-cost fabrication and long-cycling stability. However, the Na-S batteries need to operate at high temperatures (> 300 oC) to maintain the molten state of sodium anode and sulfur cathode, which requires extra energy and raises safety issues when the solid electrolyte membrane fails. Therefore, low-temperature all-solid-state Na-S batteries (such as 60 oC) are highly desirable because of the improved safety and a lower operating temperature. To achieve high sulfur-specific capacity and long-cycling stability, the stable interfaces between electrodes and solid-state electrolyte are important for all-solid-state Na-S batteries. Herein, we demonstrate a strategy using Na alloy anodes to replace Na metal anode to solve the issues of unstable interface between Na metal and solid-state electrolytes. Na-Sn and Na-Sb alloys are first compared in terms of their alloying/dealloying process to identify the advantage of Na-Sb alloy as the anode. The Na-Sb alloy anode shows its superior stability against the solid electrolyte and undergoes a stable Na alloying/dealloying process at 0.04 mA cm-2 for over 500 hours. Sulfur-carbon composites with confined sulfur nanostructure were synthesized via the sulfur vapor deposition method and further utilized in full cells. Combining the optimized Na-Sb alloy anode and sulfur composite cathodes, the all-solid-state Na alloy-S battery shows improved rate performance and a high sulfur-specific capacity of 1377 mAh g-1 with good capacity retention of 70 % after 180 cycles at 60 oC (Figure 1a and b). Postmortem analysis of both the anode and cathode shows a reversible discharge/charge process after the first cycle and undergoes significantly rearranged distributions of carbon and solid electrolytes after 180 cycles due to severe volume change induced by repeated sodiation/desodiation process. These research results show a high sulfur specific capacity with long-cycling stability and shed light on further improving next-generation Na-S energy storage systems.

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(Invited) Highly Stable, Crosslinked Polymer Membranes for Non-Aqueous Flow Batteries
Authors: Crivellaro Giovanni , Vezzu Keti , Pagot Gioele , Sgarbossa Paolo , Di Noto Vito
Published: September 2023

Long-term energy storage is a crucial stepping stone for the introduction of renewable sources in the energy mix due to their intermittent nature. Non-aqueous Flow Batteries (NFBs) are expected to operate at higher potential differences in comparison to conventional aqueous systems, thus yielding an improved power density. However, among the several issues of NFBs, it is pivotal to develop ion-conducting separators stable in organic solvents.

Here we present a new family of ionomers which proved promising as candidates to implement this crucial function. The ionomers are founded on the strong ionic interactions between the functionalities of a polyamide-based material (P) and a perfluorosulfonic acid macromolecule (N). The latter interactions establish crosslinks between the two starting macromolecules. Consequently, the polymeric structure of the final ionomer is reorganized, improving the mechanical properties and curtailing the swelling upon immersion in organic solvents.

The membranes obtained from two of the proposed ionomers, labelled “P-N0.77” and “P-N0.89”, show a swelling < 7% after 1000 hours of immersion both in acetonitrile (ACN) and in a 1:1 vol./vol. mixture of ethylene carbonate and propylene carbonate (EC:PC). Upon exchanging the membranes with tetraethylammonium (TEA+) cations, a common benchmark mobile specie for NFBs, it is shown that: (i) P-N0.77 exhibits a conductivity of 0.4∙10-3 S∙cm-1 and 0.9∙10-3 S∙cm-1 at 25°C in 0.1 M TEA+ in ACN and 0.1 M TEA+ in EC:PC, respectively; and (ii) P-N0.89 shows a conductivity of 1.5∙10-3 S∙cm-1 and 0.5∙10-3 S∙cm-1 in the same conditions.

These results suggest that the proposed materials are suitable for application in NFBs, opening the door to the long-term operation of these devices.
Taffit: An Algorithm for Fitting Tafel Data
Authors: Coduto Joshua Richard , Leddy Johna
Published: September 2023

Tafel analysis is widely used to characterize electrochemical kinetics and assess the properties of electrocatalysts for use in fuel cells, electrolyzers, and other applications. 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 in Microsoft® Excel® that generates a Tafel plot from an 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) for different electrodes. The algorithmic parameters correlate well with conventional methods and show increased measurement precision. Similar agreement is observed between literature and algorithmic fits of representative Tafel plots. The developed algorithm allows for straightforward, rapid, and user bias limited Tafel analysis and can be used to increase measurement quality.
Impedance Analysis of Semiconductor Electrodes Biased in the Accumulation Regime for Fuels Evolution
Authors: Spitler Mark
Published: September 2023

This work explores the theory and experimental use of impedance analyses of semiconductor electrodes in the accumulation regime of semiconductor electrodes under bias. It contrasts with the established practice of measuring capacitance of the semiconductor-electrolyte biased in the depletion region to obtain semiconductor doping densities and flatband potentials (Ufb). The goal is to establish Ufb and the solution Helmholtz capacitance for an electrode in the working bias region where research is done on semiconductor electrodes for CO2 reduction and H2 evolution.

The technique of measuring the capacitance of semiconductor electrodes when polarized in the depletion region was introduced by DeWald1 and is based upon the work of Garrett and Brattain2 where mathematical expressions were derived for the electric field of a semiconductor space charge region. A significant assumption in that work was that a Boltzmann expression could be used to determine the population of the majority charge carriers in the bands created through ionization of dopant. Research in this area is extensive and has been summarized.3

However, for degenerate semiconductors or for bias potentials of the semiconductor where the fermi level at the electrode surface equals the energy of the band edges, a full fermi function must be employed to describe population statistics in the solid. This is the condition commonly found in systems for fuels production at semiconductor electrodes. The solid state physics theory for this situation is known4 and describes the electric field in a semiconductor space charge region. However, it was put aside during the development of impedance evaluations in semiconductor electrochemistry because its mathematical complexity was too tedious to evaluate at that time. Only limits and simplifications were explored.5

With modern computational software, this theory has become straightforward to calculate and it becomes possible to apply it to experimental systems in a description of behavior over the entire range of doping and polarization. The nature of this full theoretical description will be discussed and illustrated through experimental measurements of Si and InP semiconductor electrodes.

References:

DeWald, J.F., J. Phys. Chem. Sol., 14, 1960, 155-161.

Garrett, C.G.B. and Brattain, W.H., Phys. Rev., 99, 1955, 376-387.

Memming, R., Semiconductor Electrochemistry, Second Edition, Wiley-VCH,, Weinheim, Germany, 2015.

Seiwatz, R. and Green, M., J. Appl. Phys., 29, 1958, 1034-1040.

Many, A., Goldstein, Y., and Grover, N.B., Semiconductor Surfaces, North-Holland Publishing, New York, 1971.
(Invited) Mechanisms of Nitrogen Cycle Electrochemistry for Energy and Sustainability
Authors: Klinkova Anna , Medvedev Iurii , Tatarchuk Stephen , Tobolovskaya Yulia , Li Feng , Medvedeva Xenia , Choueiri Rachelle
Published: September 2023

The production scale of ammonia is significant and is continuing to expand for applications in agriculture and energy. The degradation of its access is imperative to nitrogen balance. While at present thermocatalytic reactions to produce ammonia (Haber-Bosch process), nitric acid (Ostwald process) and urea (Bosch-Meiser process) dominate the artificial nitrogen cycle, the transition to sustainable production is currently driven by the development of electrochemical methods to replace traditional practices. Nitrogen cycle electrocatalysis, including nitrogen fixation, degradation and transformation of available nitrogen are attracting considerable attention in recent years. This talk will first briefly overview the emerging electrocatalytic technologies for both sustainable production of ammonia/urea and ammonia pollution mitigation; after this introduction, the talk will focus on the developments in electrooxidative ammonia and urea transformations in the broader context of nitrogen cycle and the complementarity and synergy of nitrogenous waste electrooxidation with cathodic production of fuels; finally, it will provide mechanistic insights into these electrocatalytic transformations to facilitate rational reaction and catalyst design.
Exploring Various Catalysts for Nitrogen Reduction to Ammonia
Authors: Dheer Lakshay , Thapa Ranjit , Waghmare Umesh Vasudeo , Bajdich Michal
Published: September 2023

Electrochemical nitrogen reduction reaction (eNRR), one of the most studied problems in catalysis, has the potential to replace the century-old Haber-Bosch process for ammonia synthesis. However, a low-cost, highly selective and efficient catalyst for eNRR is yet to be discovered. Metal based catalysts have been at the heart of numerous studies for eNRR, however there has been a shift towards metal-free catalysts due to their environmentally benign nature and low cost. In this study, we analyze 2D boron-based electrocatalysts for nitrogen reduction and explore the effect of carbon substitution on their activity. Using first-principles calculations, we demonstrate that pristine and carbon (C) substituted 𝛼 borophene catalyze eNRR at exceptionally low limiting potentials of -0.33 V and -0.25 V, respectively. These 𝛼 borophene based catalysts also show high selectivity towards eNRR over the competing hydrogen evolution reaction (HER). Our results show that C-substituted 𝛼 borophene exhibits outstanding catalytic activity towards eNRR via the distal pathway with a small activation barrier of 0.56 eV, almost half the value reported for Ru (0001). Finally, we identify two novel descriptors, adsorption energy of *NNH and charge transfer to *N2, which can be used in high-throughput screening of catalysts for eNRR. These findings demonstrate the strong potential of metal-free borophene based catalysts for efficient electrochemical reduction of N2, enabling low-cost and sustainable NH3 synthesis.

We revisit the nitrogenase FeM cofactor (M=Fe/Mo/V) based catalysts for eNRR to decipher the key mechanism at play. Further, catalysts based on transition metal nitrides (TMNs) and transition metal dichalcogenides (TMDCs) are also being explored for the study and compared with the state-of-the-art materials available. The dominance of one NRR mechanism like the Mars Van Krevelen (MvK) mechanism on TMNs over others like the dissociative NRR is also examined. These findings will provide a more comprehensive and elaborate view of the ammonia synthesis for N2 reduction reaction space.
Model Systems for Understanding Ion-Transfer Kinetics in Corrosion
Authors: Thurman Kira A. , Cannan Caitlyn M. , Kempler Paul , Boettcher Shannon W.
Published: September 2023

Copper is a valuable material in renewable energy technologies, such as catalysts on gas diffusion electrodes in electrochemical devices for the electrochemical reduction of carbon dioxide (CO2) to high-value products. By understanding the kinetics of ion-transfer in copper corrosion and deposition processes, we can gain a better understanding of the durability of devices that employ copper. Measurement of ion-transfer kinetics of bulk metal materials has a magnitude of challenges, increasing the difficulty of precisely analyzing the fundamentals of the processes. To assuage these concerns and obtain a more representative microscopic picture of Cu corrosion processes while investigating the effect of the anions on copper durability, we created several model microenvironments that employ copper underpotential deposition (UPD) on a well-ordered Au[111] surface: 1) a model system in sulfuric acid; 2) a bridging environment (methanesulfonic acid), and 3) a model microenvironment for gas diffusion (Nafion electrolyte). After analyzing these three systems, we expanded our models to investigate the effects of steric by adding ethanesulfonic acid and the effects of electronegativity by adding triflic acid. Our results demonstrate the effect of supporting anions on the ion-transfer kinetics of Cu UPD corrosion and deposition processes to give a better understanding of fundamental kinetics and mechanisms in gas diffusion environments.

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Facet-Dependent Selectivity of Rutile IrO2 for Oxygen and Chlorine Evolution Reactions
Authors: Vitale-Sullivan Molly E. , Carvalho Quinn Quinn , Stoerzinger Kelsey A
Published: September 2023

Water electrolysis is a promising route for sustainable production of hydrogen as an energy storage medium and valuable precursor for industrial chemical syntheses such as ammonia and methanol. Direct electrolysis of seawater circumvents costly desalination and purification steps to reduce the price of renewable hydrogen to achieve cost parity with carbon-intensive steam reforming. However, the significant concentration of chloride salts in seawater poses a challenge to selectivity of seawater electrolysis. In aqueous chloride electrolytes, the chlorine evolution reaction (CER) is kinetically favored over the oxygen evolution reaction (OER). Rutile-type iridium dioxide (IrO2) is a state-of-the-art electrocatalyst for water electrolysis but is also a benchmark chlorine evolution electrocatalyst in the industrial chlor-alkali process. Understanding OER/CER selectivity is needed to make seawater electrolysis a viable energy conversion technology in the future.

In this work, we seek to understand the relationship between crystallographic facet and competitive reaction pathway between OER and CER on epitaxial, rutile IrO2 thin films. We investigate facet-dependent OER and CER activity on a series of single-crystalline IrO2 thin films using a rotating disk electrode geometry. The OER/CER selectivity, reaction rate order, and reaction intermediate electroadsorption affinities are explored to add fundamental insight into the reactivity of rutile IrO2 surface. To gain further insight into OER intermediate adsorption affinities, we paired electrochemical measurements with surface-sensitive ambient pressure x-ray photoelectron spectroscopy (AP-XPS). Moving forward, our facet-dependent study of OER/CER selectivity of rutile IrO2 can be used to design selective seawater electrocatalysts for cost-effective and sustainable hydrogen production.
Experimental Determination of the Intrinsic Oxygen Reduction Kinetics on Polycrystalline Platinum and the Role of the Adsorbed Oxygen
Authors: Brandes Benedikt Axel , Buchauer Fabian Luca , Hjelm Johan
Published: September 2023

The Oxygen Reduction Reaction (ORR) is a fundamental reaction in electrochemical devices such as fuel cells and sensors. The ORR only occurs on few catalytically active surfaces, mainly platinum and its alloys and understanding its mechanism is critically important to develop new catalysts and applications. In contrast to the related Hydrogen evolution/oxidation reaction, the intrinsic ORR activity is rarely determined due to simultaneous formation of Pt-O species. Therefore, the ORR activity is measured at a benchmark potential making its susceptible to the measurement characteristics, such as "activation", scan rate, and scan direction.

We found that by using a specially designed experimental procedure one can separate the effect of Pt-O on the ORR kinetics without extensive modelling or fitting. As a results an exemplary Pt-O corrected Tafel plot on polycrystalline platinum is displayed in figure 1.

In this presentation we will discuss the underlying method, its application on a range of different ORR environments, the nature of the Pt-O species, and the implications for ORR mechanism itself.

Figure 1
(Invited) Using Single Nanoparticle Electrochemistry to Better Understand the Oxygen Evolution Reaction at Cobalt Oxide Nanocatalysts
Authors: Tschulik Kristina , Amin Hatem M.A. , Hosseini Pouya , Corva Manuel , Liu Zhibin
Published: September 2023

Transition metal oxides are highly promising catalysts for alkaline water splitting thanks to their relatively high abundancy and high catalytic activity. Due to their limited electrical conductivity they are often used as nanoparticles and their catalytic performance is assessed based on experiments at composite electrodes. Besides the nanocatalyst of interest, these electrodes contain catalytically inactive binders and conductive additives. This makes it highly challenging – if not impossible – to distinguish influences of catalyst properties from matrix effects. For example, observed effects of particle morphology on electrocatalytic activity may simply originate from different wetting/blocking of catalyst active sites by the used additives or by different iR drop across the composite film, instead of signifying different charge transfer kinetics [1]. To overcome this limitation, we use single nanoparticle electrochemistry and study electrocatalysis at individual catalyst nanoparticles [2]. Employing this approach, we are able to clearly reveal that Co3O4 nanocubes are more active for the oxygen evolution reaction (OER) than spheres. Moreover, we can link our experimental data to theory data obtained from DTU+U calculations, thanks to the comparably small size of the electrochemical system [3]. For OER catalysis at single Co3O4 nanocubes in KOH(aq), we demonstrate and rationalize the effect of support materials on catalyst activity that had been debated previously [4].

References

[1] N. Blanc, C. Rurainsky, K. Tschulik, J. Electroanal. Chem. 872(2020)114345

[2] A. El Arrassi, Z. Liu, M. V. Evers, N. Blanc, G. Bendt, S. Saddeler, D. Tetzlaff, D. Pohl, C. Damm, S. Schulz, K. Tschulik, J. Am. Chem. Soc. 141 (2019) 9197

[3] Z. Liu, H. M.A. Amin, Y. Peng, M. Corva, R. Pentcheva, K. Tschulik, Adv. Funct. Mater., (2022) accepted.

[4] Z. Liu, M. Corva, H.M.A. Amin, N. Blanc, J. Linnemann, K. Tschulik, Int. J. Mol. Sci. 22 (2021)13137.

Figure 1: Single nanoparticle electrochemistry shows higher OER activity for cobalt oxide cubes than spheres [3].

Figure 1
(Invited) Measuring the Temporal Evolution of Surface Intermediates in Electrocatalysis
Authors: Wilson Andrew J. , Joshi Padmanabh
Published: September 2023

Ensemble measurements in electrocatalysis average over populations of single entities such as transient chemical intermediates and active sites. Ensemble-averaged empirical data provides general trends in reactivity but lost is a vast amount of information on how molecules interact and evolve on an electrocatalyst surface which could reveal over- or underperforming subpopulations within an ensemble. To validate and improve current theoretical predictions of reaction pathways, direct measurements of intermediates in electrocatalysis are required. Toward this goal, I will discuss our development of time-resolved surface-enhanced Raman scattering (SERS) microscopy as a tool to measure the evolution and dynamics of surface intermediates formed on metallic electrodes in CO2 reduction. Combining diffraction-limited spatial resolution with µs temporal resolution, we observe the formation of surface-bound CO ca. 1 V below the ensemble onset potential. Further, our time-resolved spectroscopy reveals the timescales of surface intermediate accumulation on and evolution from electrode surfaces, providing insight into the residence times of intermediates. Time-resolved SERS microscopy reveals the action of surface intermediates previously hidden by spatially and temporally averaged ensemble measurements, providing new mechanistic insight to the CO2 reduction reaction.
Enhanced Methanol Oxidation Using Polymer-Incorporated Ultra Rough Pt Electrodes
Authors: Hua Qi , Alghoraibi Nawal , Chen Xinyi , Gewirth Andrew A.
Published: September 2023

We report on the methanol oxidation reaction (MOR) on very rough Pt surfaces. Numerous previous studies show that the cyclic voltammetry of MOR on Pt exhibits hysteretic behavior due to Pt oxide poisoning during the anodic scan at higher potentials. Only after the Pt oxide is removed during the cathodic scan is the Pt surface reactivated and MOR activity resumed (Fig. 1). We developed an electrodeposition method yielding Pt electrodes with high roughness factors (Rf > 80) controlled by varying deposition time. These rough electrodes exhibit linear MOR without hysteresis (Fig. 1), indicating the rougher Pt surface is resistant to poisoning during MOR up to potentials of 1.4 V vs. RHE. The effect is found in either acidic or basic electrolyte. Further studies show the roughness effect is related effective increase in the surface concentration of methanol and effective decrease in the surface concentration of water. The lower water activity inhibits Pt surface oxidation and facilitates methanol oxidation. Treatments to artificially decrease surface water concentration have a similar effect. This study provides methods to increase the rate of organic molecule oxidation at electrode surfaces and is relevant to both electro synthesis and direct methanol fuel cell applications.

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Investigating Lanthanide Ions for Catalysis of Alcohols
Authors: Lazicki Andy Peter , Leddy Johna
Published: September 2023

Small molecule alcohols (methanol, ethanol, 2-propanol) are fuels limited by their oxidative kinetics. For these small molecules to be used as fuels, catalysts must be developed. One domain of chemicals which has not had its catalytic properties entirely studied are lanthanides. These lanthanides contain many properties not found in d-block metals or other compounds frequently used as catalysts. The ability to catalyze oxidation of small molecule alcohols is studied here. Performance of these lanthanides as a catalyst are measured for each small molecule using common voltametric techniques. Plausible mechanisms for any charge transfer enhancement are also estimated.
(Invited) Unraveling the Electrocatalytic Reduction Mechanism of Aliphatic Enols on Copper in Aqueous Media
Authors: Cui Zhihao , Dong Xing'an , Cho Sung Gu , Tegomoh Modeste N'neckmdem , Dai Weidong , Dong Fan , Co Anne C.
Published: September 2023

Aldehydes and their enol tautomer are important intermediates during electrocatalytic CO2 reduction to C2 and C3 products on polycrystalline Cu catalyst. In this work, we present that thermodynamically unfavored enols in aqueous media can be reduced to alkenes and alkanes on Cu where the rate-determining step of the evolution of these hydrocarbons is likely an electron transfer step.
Microwave Enabled Incorporation of Singlemetal Atoms in Holey Graphene
Authors: Ouyang Junjie , Zhang Zhiyuan , Lockard Jenny , Lahanas Nicole , Solovyev Mikhail , He Huixin
Published: September 2023

Single-atom catalysts (SACs) can simultaneously maximize the utilization of metal atoms and minimize side reactions, achieving high catalytic activity and selectivity, which are not attainable for the conventional nanoparticle-based catalysts. SACs have been intensively investigated for a wide range of reactions and great progress has been achieved. However, most of the carbon substrates supporting the SACs are highly defective carbon materials, which are not only low conductivity but also low stability against oxidation. In the recent review articles, carbon matrix oxidation has been identified as the most important degradation mechanism of PGM-free catalysts in PEMFC cathodes. The stability issue is also especially critical when the SACs are used in Fenton-like catalytic reactions. In this work, we present a novel approach to quickly fabricate SACs in which the single metal atoms are incorporated in highly conductive holey graphene. This novel approach takes advantages of the rapid heating capability of microwave when highly conductive holey graphene is used as the microwave absorber. The initial assumption of the method was based on the rapid heating/cooling capability of microwave heating to quickly carbonize the organic linkers in a metal-organic framework (MOF) into a conductive carbon network, leaving no time for the diffusion of the metal atoms, therefore aggregation of the metal atoms to form clusters can be largely avoided. Interestingly, instead of stopping the diffusion of metal atoms in the MOF, microwave heating appears causing the metal atoms flying out from the MOF particles and incorporated into the basal planes of the holey graphene. Using PCN222-Fe and PCN222-Cu MOF as the precursors, Fe and Cu SACs were fabrications, in which the Fe and Cu catalytic centers are incorporated into the basal planes of the holey graphene. It is worth to mention that the non-hole regions of the holey graphene are nearly defect free, which is in high contrast to the highly defect carbon materials, ensuring high stability of the catalysts against oxidation. The catalytic performance of thus fabricated Cu and Fe SACs are studied in oxygen reduction reaction. Most importantly, the hydrogen peroxide reduction/oxidation reactions were also studied. These results provide fundamental basis for these catalysts in Fenton-like catalytic reactions.

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Stationary Pattern Formation in Iron Electrodissolution with Two Cells: Effects of Serial or Parallel Coupling
Authors: Bordoh Lawrence , Kiss Istvan Z.
Published: September 2023

We investigate the stationary pattern formation for two coupled cells at constant circuit potential. Two configurations are explored: two cells in serial and parallel. In each cell the anode is iron electrodissolution and the cathode is hydrogen ion reductions on a large surface area Pt electrode with sulfuric acid electrolyte. Iron electrodissolution in sulfuric acid exhibits negative differential resistance due to electrode passivation by the surface oxide where the stability of the surface oxide is dependent on electrode potential and pH at the electrode interface. In the presence of ohmic potential drops (e.g., due to solution or external resistance), bistability can occur where the active and passive states co-exist at a given circuit potential. First, we investigated the patterns that emerge for two serially coupled iron electrodissolution in sulfuric acid. Investigation of the forward scan potentiodynamic I-V curves reveals sequential passivation of electrodes in no particular order and a potential region is identified where one electrode is passive and the other is inactive, and thus a stationary pattern is formed. Numerical simulations and equivalent circuit network modeling of the experimental set-up reveals a bidirectional negative coupling topology as a consequence of serial configuration, providing insight into the pattern formation. The patterns are interpreted with a kinetic model which shows that the coupled NDR system can exhibit symmetry breaking transitions in the presence of negative coupling. Next, we studied stationary pattern formation in two parallel cells. In contrast to the serial placement, the potentiodynamic I-V curves reveal simultaneous passivation of the two electrodes. The electrode potential versus circuit potential plot displays a uniform state of electrodes throughout the scan. The corresponding modeling showed that the lack of sequential passivation and the presence of uniform states were due to the inherent bidirectional positive coupling in the system. The experiments demonstrate the rich dynamical response of a coupled negative differential resistance systems to generate stationary patterns similar to Turing patterns that are used to interpret morphogenesis in biological systems. The theoretical understanding and insight gained from modeling and simulating observed patterns of relatively smaller electrochemical cells could be crucial in the accelerated understanding, design, and control of battery packs that utilize serial and parallel coupled electrodes.
(Digital Presentation) Data-Driven Discovery of Luminescent Materials
Authors: Xie Rong-Jun
Published: September 2023

Luminescent materials play an important roles in lighting, display, plant growth, anti-counterfeit, medical and bio-technologies. The search for luminescent materials with desired properties never stops, but relies mostly on the trial-and-error approach, which is time-consuming and labor-intensive. Several methods have been proposed to accelerate the discovery of new luminescent materials, among them the data-driven one attracts much attention. In this presentation, two types of luminescent materials for different applications will be reported. Firstly, we build an emission-prediction model based on machine learning, and using this model found five Eu2+-doped nitride phosphors with highly efficient near-infrared (NIR) emissions. Secondly, we propose selection rules to discover laser phosphors and mechanoluminescent materials based on the structure-property relations, respectively. The applications of these phosphors in NIR detectors, laser lighting and stress mapping will also demonstrated.
A Universal Hydrogel Microneedle for on-Site Detection of Small Molecules, Proteins, and Ribonucleic Acids
Authors: Keyvani Fatemeh , Zheng Hanjia , Kaysir MD Rejvi , Mantaila Dragos , Poudineh Mahla
Published: September 2023

Point-of-care testing (POCT) of clinical biomarkers is critical to health monitoring and timely treatment, yet biosensing assays capable of detecting biomarkers without the need for costly external equipment and reagents are limited. Blood-based assays are, specifically, challenging as blood collection is invasive, and several processing steps are required. A promising alternative to blood is interstitial fluid (ISF), which originates from blood and fills the extracellular space; thus, it has common biomarkers with plasma/serum while also containing biomarkers unique to the local cells. A wide range of metabolites, including amino acids, lipids, nucleotides, and protein biomarkers, can be detected in ISF, emphasizing the potential of ISF for health monitoring. Microneedle (MN)-based biosensors have recently emerged as a promising approach for investigating the ISF. They enable minimally invasive penetration through the skin for ISF access. Specifically, Hydrogel-based MNs have two main advantages; i) their fabrication is cost-effective and simple, ii) they are highly biocompatible. Therefore, they overcome the challenges with conventional solid MNs. However, Hydrogel Microneedles (HMN) capable of both extracting ISF and sensing an analyte on-microneedle (without any need for post-sampling processing) have been limited. Here, we report a versatile assay that employs HMNs to both extract (ISF) and perform on-MN sensing of a specific analyte/biomarker in a minimally invasive manner. Our assay incorporates graphene oxide-nucleic acid (GO.NA) optical sensors for sensing. The GO.NA optical sensor consists of GO nanosheets conjugated to fluorophore-modified nucleic acid (NA), in which GO acts as a quencher. Single-stranded NAs have high affinity for binding to GO, therefore, in the absence of the biomarker of interest the NAs are tightly bound to GO; in turn, their fluorophore tag is quenched. However, in the presence of a specific biomarker, the NAs bind to their target, inducing a conformational change that distances the fluorophore tag from GO, leading to fluorescence recovery and generation of an optical signal. GO also acts as a substrate for NA immobilization; therefore, it protects the NA from degradation and prevents any potential NA release from HMN-GO.NA. To enable microscope-free patch visualization and optical measurements for POCT, we developed a miniaturized smartphone-based system that captures fluorescence images of the HMN-GO.NA patches (Scheme 1A and 1B), which are then analyzed using freely available software (ImageJ). Our system could successfully measure six clinically important biomarkers (glucose, uric acid, insulin, and serotonin as well as microribonucleic acid 210 and 21) in-vitro (using phantom gel) and ex-vivo (using porcine skin). Further, we have been able to accurately detect glucose and uric acid in live diabetic animal models, proving the efficacy of our system.

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Testbed for Simulating Pulsewaveform for Development of Wearable Piezoresistive Pressure Sensors
Authors: Jafarizadeh Borzooye , Chowdhury Azmal Huda , Pala Nezih , Wang Chunlei
Published: September 2023

Due to their non-invasive method of continuous monitoring of weak human physiological data, flexible and skin-mountable wearable health monitoring devices have attracted a lot of attention in recent years. According to their mode of operation, ultra-sensitive pressure sensors can generally be divided into piezoresistive, capacitive, triboelectric, and piezoelectric sensors. Particularly, piezoresistive sensors have received a lot of attention due to its rapid response, wide detection range, straightforward structure, and comparatively easy signal measuring system. Although previous attempts to obtain the complete pulse waveform of the human heartbeat were successful, their signal capture required the use of unwearable measuring equipment. In order to resolve this shortcoming of the current supposedly wearable systems, we outline three requirements for a sensor to be wearable (i.e. could be paired with a simple and compact signal acquisition device). The first of these is the sensitivity; through a complete literature review we determine the lower limit of sensitivity that if obtained, the sensor can acquire the pulsewaveform from the body peripheries such as wrist or ankle. Second is the response time of the sensor. The piezoresistive sensor must have a shorter response time than the period of fastest heartbeat. And lastly is the cyclability; the durability tests of the sensor must show ample stability and consistency in the signal output after operation for months.

To verify that the sensors pass the requirements above, we have custom-built a testbed capable of measuring these three characteristics. The testbed specifically makes use of a secondary pressure sensor to confirm the sensitivity. Secondly, by using an encoder instead of merely relying on a sensor's rise or fall time, it is capable to more accurately determine the response time of the sensor. Furthermore, because the testbed is motorized, it is streamlined to mimic operation over an extended cycles.

Finally, in this study we fabricated an exemplary piezoresistive pressure sensor using environmentally friendly materials and tested it in the testbed and then mounted it on the wrist of a human subject and acquired the pulsewaveform with a simple and wearable signal acquisition device to confirm the capability as a wearable pulsewave monitoring device. The details of this study will be presented in the meeting.
Multi-Function Sensory System for Detection of Ammonia
Authors: Navaei Milad , Park Jinho , Heist Christopher A. , Song Judy , Swarts Matthew
Published: September 2023

Ammonia is a highly toxic gas with implications for human and animal health. This effort aims to develop a low-cost multi-array orthogonal sensor for detecting a low concentration of ammonia in a poultry house. To approach this problem, a novel multi-array electro-thermal and Metal oxide solid state gas sensor are developed. Its design consists of a microfabricated suspended MEMS bridge, a resistance temperature detector (RTD), a low-pass loop filter H(s), and a heater amplifier for the micro-oven. The resistive element is used as the micro-oven heater. The sensing platform comprises of a low-cost thermal conductivity sensor (TCD), and Metal oxide (ZnO, NiO-ZnO, Au-ZnO) solid-state sensors. From this study. we concluded that the thermal conductivity sensor provides a linear level of detection(LOD) of 1 ppm at 30-80 % relative humidity with 100 ns response time and 5 years of lifetime while the Au-ZnO solid state sensor has sub ppm limit of detection and response time of ~ 2 minutes.

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Electrolyte-Insulator-Semiconductor (EIS) Device with Hafnium Dioxide (HfO2) for pH Detecting
Authors: César Rodrigo REIGOTA , Diniz Jose Alexandre , Vidal Melissa , Cotrin Ricardo , Massaroto Rentao
Published: September 2023

In this work Electrolyte-Insulator-Semiconductor (EIS) device has been developed for pH measurements. This device operates as a Metal-Oxide-Semiconductor capacitor but instead of having the metal contact electrode, an electrolyte solution and a reference electrode are used to apply voltage. As dielectric material and sensitive membrane was chosen hafnium dioxide (HfO2). This film was obtained by RF sputtering, and was structurally characterized by Raman and Ellipsometry. The structural characterization of HfO2 thin film shows the presence of tetragonal phase, physical thickness of 50 nm and refractive index of 1.89, close to stochiometric of 1.91. Was developed MOS capacitors to make the electrical characterization of HfO2 thin films in order to determine the thin film properties, defined by high dielectric constant value (high-k), lower charge density (Q0/q) and flat-band voltage (VFB) around -0.9V. The electrical characterization done by Capacitance x Voltage (CxV) curves revealed high dielectric constant, VFB of 0.02V and Q0/q in the order of -10+12/cm2. The Current x Voltage (IxV) curve shows that the current through the dielectric is approximately 1x10-9A. With dielectric characterized it was possible to develop the EIS device. From electrical characterization it was possible to test the integrity of the electrodes and determined the sensitivity of the device. For electrical measurement of EIS was used Normalized Capacitance x Voltage curve (CxV curve) using different pH (3, 4, 5, 7, 9, 10 and 12) solutions. From the flat band voltage (VFB) of the Normalized CxV curves was possible to determine the sensitivity of the device of 78mV/pH. This result is greater than the Nernst level and greater than results found in the literature.
In Operando Measurement of the Lithium-Ion Concentration in the Battery Electrolyte to Study Degradation Modes
Authors: Wahl Markus Solberg , Lamb Jacob , Boles Steven T , Burheim Odne Stokke
Published: September 2023

In operando measurements of the lithium-ion concentration inside a lithium-ion battery (LiB) using a fiber-optic sensor are demonstrated. The concentration changes in the electrolyte are correlated to the incremental capacity response of the battery during charge and discharge. The goal is to study battery degradation based on the dynamic and state-of-charge dependent concentration of lithium ions in the electrolyte.

Batteries lose capacity over time, both due to charging/discharging and to shelf ageing (calendar ageing). Extending the lifetime of a battery directly reduces its environmental footprint. This ageing is caused either by i) unwanted chemical reactions, reducing the number of available lithium-ions or increasing the impedance, or ii) by physical changes that reduces the available lithium storage capacity of the electrodes. Both mechanisms affect the spatial distribution of lithium ions.

Ageing has traditionally been studied through monitoring the operational performance (e.g., coulombic capacity, internal resistance), or through post-mortem investigations. Other advanced methods, such as thermal neutron imaging or X-ray tomography has also been used to estimate the internal composition of the battery through image analysis [1,2]. This study presents live concentration measurements using an optical fiber placed between the electrodes. The intrinsic properties of optical fibers (e.g., small, chemically inert, electrically insulating) make them ideal for internal sensing in the chemically harsh interior of a battery.

The fiber is placed in the electrolyte between the electrodes, see Fig. 1a. Because the reflected intensity depends on the concentration of lithium ions (Fig. 1b), we are able to demonstrate and analyze how the concentration changes during cycling (Fig. 1c). Both single-cycle and long-term effects are investigated. Information about how the lithium concentration changes during cycling is valuable both as an input parameter in battery modelling, and to increase the understanding of battery ageing. For the latter, the lithium-concentration during cycling of batteries is evaluated in correlation with an incremental capacity analysis.

Siegel, J.B.; Lin, X.; Stefanopoulou, A.G.; Hussey, D.S.; Jacobson, D.L.; Gorsich, D. Neutron Imaging of Lithium Concentration in LFP Pouch Cell Battery. J. Electrochem. Soc.
2011, 158, A523, doi:10.1149/1.3566341.

Senyshyn, A.; Mühlbauer, M.J.; Dolotko, O.; Hofmann, M.; Ehrenberg, H. Homogeneity of lithium distribution in cylinder-type Li-ion batteries. Sci. Rep.
2015, 5, 1–9, doi:10.1038/srep18380.

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