bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Pt/C Catalyst Using Carbon Support Derived from Tamarind Seeds through Hetroatom Doping for Oxygen Reduction Reaction
Authors: Kharwar Yashwant Pratap , Akula Srinu , Sahu Akhila Kumar , Ramanujam Kothandaraman
Published: February 2020

Abstract

In the process of developing highly active and stable Pt/C catalyst with low Pt loading for the reduction of oxygen in fuel cells, the metals are supported on porous carbon derived from natural resources such as plant bio mass, chitosan waste, straw, honeysuckles, coconut shells, orange peels, waste paper etc.1–4 Porous carbon derived from such sources are low cost and high specific surface area, well tuned textural properties, pore geometry renders towards prominent choice for support material through hetero atom doping to enhance the catalytic activity.5,6 In the present study Tamarind seeds (Tamarindus indica) utilized to derive the porous carbon for hetero atom doping followed by Pt deposition using traditional, liquid phase reaction (LPR) method.7 The synthesis process involves optimization of temperature, N-content in the catalyst followed by Pt loading by virtue of their electrochemical ORR behavior. The final optimized catalyst will be using in fuel cell as cathode catalyst.

References

W. Yang, Y. Zhai, X. Yue, Y. Wang, and J. Jia, Chem. Commun., 50, 11151–11153 (2014).

T. Ramesh, N. Rajalakshmi, and K. S. Dhathathreyan, J. Energy Storage, 4, 89–95 (2015).

X. Ma, C. Feng, W. Zhou, and H. Yu, J. Power Sources, 307, 105–111 (2016).

L. Liu, Q. Xiong, C. Li, Y. Feng, and S. Chen, RSC Adv., 5, 89771–89776 (2015).

A. Srinu, S. G. Peera, V. Parthiban, B. Bhuvaneshwari, and A. K. Sahu, ChemistrySelect, 3, 690–702 (2018).

P. Chen et al., Energy Environ. Sci., 7, 4095–4103 (2014).

Y. Bai, L. Lu, and J. Bao, Int. J. Electrochem. Sci., 11, 2046–2057 (2016).

Figure 1
3D Analysis of Observed and Simulated Microstructure Evolution in SOFC Anodes
Authors: Wieler Matthias , Wankmüller Florian , Weber André , Hoffrogge Paul Wilhelm , Schneider Daniel , Nestler Britta , Haremski Patricia , Lupetin Piero
Published: February 2020

An important degradation mechanism in solid oxide fuel cells (SOFCs) is the microstructural evolution of Ni-YSZ anodes caused by diffusional transport of nickel under operating conditions. In this work, we carry out 3D analysis on several data sets from FIB-SEM reconstructions of a full-ceramic co-sintered SOFC as well as from large-scale phase-field simulations, in order to obtain a quantitative understanding of the different microstructure evolution effects and their impact on anode degradation.

The experimental data stem from FIB-SEM reconstructions of both newly fabricated anodes and anodes aged for ca. 1000h under operating conditions. The simulated data stem from large-scale phase field simulations that have been initialized with a reconstructed microstructure. The underlying phase-field model incorporates both volume diffusion of nickel and interface diffusion along the Ni surfaces, grain boundaries, and Ni-YSZ interfaces. The required material parameters (interface energies and diffusivities) are determined partly by ab-initio simulations and partly by thermal grooving experiments on bicrystalline and polycrystalline nickel.

For the 3D analysis, we calculate standard microstructural features such as volume fractions, active and inactive three-phase-boundary (3PB) length, and tortuosity, and we use the transmission line model to calculate the expected anode performance. Comparison with the measured anode performance shows that the observed decrease of 3PB length explains the measured degradation only partly, while the main degradation factor is loss of connectivity of the nickel phase. To understand the connectivity loss in more detail, we carry out a bottleneck analysis to quantify the gradual tightening of the bottlenecks. In addition, we statistically assess the spatial homogeneity, and we calculate several shape descriptors such as interface areas and local structure size, which allows us to show that nickel relocates over considerable distances from small pores to larger pores within the YSZ skeleton.
Solid Acid Catalysts from Biowaste and Their Potential for Biodiesel Production
Authors: Memon Safia Sanam
Published: February 2020

Biodiesel production at commercial scale is viable option to substitute petrodiesel in Pakistan. Solid catalyst for biodiesel production has advantages over homogenous catalyst in terms of ease of separation, reusability, economic efficiency etc. This will focus on the production of carboneous material using green carbonization procedure from various biowaste, followed by sulfonation. Biowastes were hydrothermally carbonized under subcritical water conditions under endogenous pressure for more than 4 hours. Resulting carboneous materials were refluxed with sulfuric acid. Structural and morphological characterization, acid density and catalytic efficiency of such materials will be discussed in this study. The sulfonated carbon-based solid acid materials showed high acidity and good catalytic activities for the esterification of oleic acid with methanol.
Theoretical Investigation of the Effects of Metal Cations on Oxygen Reduction Reaction in Non-Aqueous Li-Air Batteries
Authors: Rawal Saurin Hiren , Drewry Benjamin , Shelton William A , Xu Ye
Published: February 2020

Non-aqueous Li-air batteries with high theoretical gravimetric energy density represent one of the potential future technologies to replace Li-ion secondary batteries.1-2 This has led to renewed interest in the fundamental aspects of the oxygen reduction reaction (ORR) and oxygen evolution reaction in non-aqueous electrolytes. We present a DFT based theoretical study on the formation of different bulk microstructures as discharge products when exposed to different dopant cation. The dopant being various solvated metal cations. These microstructures can be either crystalline or amorphous and are different from the standard crystalline P63/mmc Föppl structure of Li2O2.3 We explore the possible improvements in the electron mobility in these microstructures compared to the crystalline P63/mmc Föppl structure of Li2O2.4 Furthermore, the effect of the cation adsorption on Li2O2 crystalline surfaces is explored to assess the incorporation of these metal cations and its likely impact on the subsequent ORR, including the modification of the surface electronic structure, which may lead to improvement in surface electron conductivity and crystal growth and positively impact subsequent oxygen evolution reaction.

References

Bruce, P. G.; Freunberger, S. A.; Hardwick, L. J.; Tarascon, J. M., Li-O-2 and Li-S batteries with high energy storage. Nature Materials
2012,
11 (1), 19-29.

Luntz, A. C.; McCloskey, B. D., Nonaqueous Li–air batteries: a status report. Chem. Rev.
2014,
114 (23), 11721-11750.

Radin, M. D.; Monroe, C. W.; Siegel, D. J., How dopants can enhance charge transport in Li2O2. Chem. Mater.
2015,
27 (3), 839-847.

Radin, M. D.; Rodriguez, J. F.; Tian, F.; Siegel, D. J., Lithium peroxide surfaces are metallic, while lithium oxide surfaces are not. J. Am. Chem. Soc.
2011,
134 (2), 1093-1103.
(Invited) Polymer-Ceramic Composite Electrolytes for All-Solid-Sate Lithium-Ion Batteries
Authors: Yang Hui , Wu Nianqiang
Published: February 2020

This talk will present our effort to develop the polymer-ceramic composite electrolytes for all-solid-sate lithium-ion batteries. Li-ion conducting metal oxide nanofibers are fabricate with electrospinning techniques. The electrospun nanofibers serve as the three-dimensional scaffold for in-situ polymerization of matrix. The electrochemical performance of the Li-ion battery with the polymer-ceramic composite electrolyte is tested in terms of energy density, rate capability and cyclic stability.
(Invited) Directing Mg-Storage Chemistry in Organic Polymers Toward High-Energy Mg Batteries
Authors: Dong Hui , Liang Yanliang , Yao Yan
Published: February 2020

Magnesium batteries could offer high energy density and safety due to the non-dendritic Mg metal anode. However, Mg2+ ingress into and diffusion within cathode materials are kinetically sluggish. It is therefore intriguing that recently organic cathodes were shown to deliver high energy and power even at room temperature. Herein we reveal that previous organic cathodes likely all operated on a MgCl-storage chemistry sustained by a large amount of electrolyte that significantly reduces cell energy. We then demonstrate Mg batteries featuring a Mg2+-storage chemistry using quinone polymer cathodes, chloride-free electrolytes, and a Mg metal anode. Under lean electrolyte conditions, the Mg2+-storing organic cathodes deliver the same energy while using $10% of the amount of electrolyte needed for the MgCl-based counterparts. The observed specific energy (up to 243 Wh kg-
1), power (up to 3.4 kW kg-
1), and cycling stability (up to 87% at 2,500 cycles) of Mg-storage cells consolidate organic polymers as promising cathodes for high-energy Mg batteries.
Suppressing Reactivity of Sulfides in Solution Processing Enables Scalable Manufacturing of Thin, Flexible Solid-State Electrolytes
Authors: Tan Darren Huan Shen , Banerjee Abhik , Deng Zhi , Wu Erik , Nguyen Han , Doux Jean-Marie , Wang Xuefeng , Cheng Ju-hsiang , Ong Shyue Ping , Meng Shirley , Chen Zheng
Published: February 2020

All solid-state batteries (ASSBs) have the potential to deliver higher energy densities, wider operating temperature range and improved safety compared with today’s liquid electrolyte-based batteries. However, they still face challenges that limit their commercialization resulting from thick solid-state electrolytes (SSEs), and poor processability due to their unstable chemistries. Existing studies on solvent-binder based casting methods to reduce SSE thickness and improve processability still lack crucial fundamental understanding of the behavior and selection criteria for different SSE-binder-solvent systems. In this work, we attempt to isolate various SSE-binder-solvent system behaviors and study their chemical and electrochemical compatibilities using both bulk and surface sensitive characterization tools. With these findings, we introduce a novel binder-solvent combination that significantly reduces SSE thickness and improves processability of ASSBs while maintaining high ionic conductivity. The resulting organic/inorganic composite SSE was found to be stable against lithium metal by plating and stripping over extended cycles. This study suggests the importance of understanding fundamental SSE-binder-solvent interactions and provides a potential design strategy for scalable production of ASSBs.
(Invited) Good Food, Paper Napkins, and New Ideas: A PEM-Fuel Cell Community at Its Best
Authors: Kreuer Klaus-Dieter
Published: February 2020

PEM-fuel cell research and development is highly interdisciplinary. Material science, chemistry, physical chemistry, physics and engineering problems need to be defined and solved with many inter-dependencies making R & D strategies highly complex and vulnerable to fail. The amazing progress we have seen has required not just many experts in their particular field but also a very productive communication culture for exchanging and developing ideas. Shimshon Gottesfeld is a cornerstone of this community combining technical knowledge with an extraordinary capability to stimulate and guide discourse. Here, I will present some of our own research that was inspired in part by the many stimuli that Shimshon gave to us. Over good meals and ad hoc notes on napkins, we asked ourselves questions such as: Through which mechanisms are proton, hydroxide ion, water, and even methanol transport related in fuel cell membranes? Are “hydroxide ion exchange membrane” (HEM) fuel cells feasible? Can we use hydrocarbons as membrane materials and ionomers in PEM fuel cells and electrolyzers? The world is radically changing in many respects and so does the way we do science. I hope younger researchers can continue to draw hope and inspiration from Shimshon’s model of open, provocative and friendly discourse driven by intellectual curiosity [1] as a way for making progress in solving complex problems.

Jillian M. Buriak and Carlos Toro Chem. Mater.
2014, 26, 6651−6652
(Invited) What’s Killing My Fuel Cell? a Retrospective on Polymer Fuel Cell Poisoning and Degradation Research
Authors: Garzon Fernando H , Mukundan Rangachary , Borup Rod L.
Published: February 2020

PEMFCs are subject to many mechanisms that abruptly decrease power output or slowly degrade long-term performance. Los Alamos National Laboratory researchers pioneered many experimental investigations and forensic characterization studies to explore these effects. These include catalyst degradation, membrane performance loss and failure, gas diffusion layer degradation, and fuel and air poisoning mechanisms. This retrospective highlights a 25+ year effort at understanding and mitigating these effects.

In the early 1990s fuel cell performance loss was observed in fuel cells which by today’s standards, had relatively high catalyst loading and utilized thick Nafion 117 membranes [1]. Carbon monoxide was already well known to poison the hydrogen oxidation reaction. The processes of Pt coarsening, Pt-M, dealloying, carbon corrosion, membrane free radical attack, foreign ion-proton exchange, ammonia and sulfurous gas poisoning, were investigated in subsequent years. Many characterization techniques, in addition to voltammetry, were employed to study these processes including: XRD, SEM, EDS, TEM, XPS, XRF, X-ray microscopy & tomography, neutron imaging and ion and gas chromatography [2]. Modeling methods from atomistic calculations to macroscopic effective medium transport models were developed to further provide insights towards mechanisms and mitigation strategies. The efforts continue today as ultralow loading platinum group metal catalysts and alloys, PGM free electrocatalysts, supports and novel membranes are being evaluated for next generation fuel cells.

References

Wilson, M. S.; Garzon, F. H.; Sickafus, K. E.; Gottesfeld, S., Surface area loss of supported platinum in polymer electrolyte fuel cells. Journal of The Electrochemical Society
1993,
140(10), 2872-2877.

Borup, R.; Meyers, J.; Pivovar, B.; Kim, Y. S.; Mukundan, R.; Garland, N.; Myers, D.; Wilson, M.; Garzon, F.; Wood, D., et.al, Scientific aspects of polymer electrolyte fuel cell durability and degradation. Chemical reviews
2007,
107(10), 3904-3951.
(Invited) Stepping in the Dark - Active Site Density and Turn over Frequency in PGM-Free Metal-Nitrogen Doped Carbon (M-N-C) ORR Fuel Cell Electrocatalysts
Authors: Strasser Peter
Published: February 2020

We honor Shimshon Gottesfeld’s several decade-long pioneering contributions to the science of fuel cells by sharing some past work on PGM catalysts, but also some very recent work on PGM-free metal-nitrogen doped carbon ORR electrocatalysts with a focus on the evaluation of the number and surface area-based density of metal (ion) surface sites using probe gas molecule adsorption and thermal desorption. We show how correlations of site density values with turn-over-frequency data can advance our understanding of PGM-free M-N-C ORR electrocatalysts and aid in a rational search for and synthesis of improved PGM-free fuel cell catalysts.
(Invited) Electrocatalysis from First-Principles: Reaction Mechanisms and Ideas for Improved Materials
Authors: Mavrikakis Manos , Elnabawy Ahmed O. , Herron Jeff A.
Published: February 2020

Density Functional Theory (DFT) has enabled the search for improved electrocatalysis, based on DFT-identified reactivity descriptors for a wide variety of reactions and surfaces1, 2. Concurrently, the inorganic synthesis community has achieved important successes towards the robust synthesis of shape-selected nanocrystals which preferentially expose certain facets and morphologies3, 4. We start this presentation by discussing our work on the structure sensitivity of ammonia electrooxidation on transition metals in alkaline fuel cells; the kind of fuel cells that Dr. S. Gottesfeld has passionately investigated for many years5. We explain the higher activity of Pt(100) versus Pt(111), and propose the binding energy of atomic nitrogen as a key reactivity descriptor for this environmentally-benign electrochemistry6. We will then present some of our work on acidic fuel cells, especially regarding the electrooxidation of formic acid on transition metals7, and, with time permitting, on Pt and Pd monolayers on transition metals. Unlike ammonia electrooxidation, we here propose two reactivity descriptors (the free energy of adsorbed CO* and the free energy of adsorbed OH*) to adequately describe the search space for improved catalysts for formic acid electrooxidation.

[1] T. Bligaard, J. K. Nørskov Electrochim. Acta. 2007, 52, 5512-5516.

[2] J. K. Nørskov, F. Abild-Pedersen, F. Studt, T. Bligaard Proc. Natl. Acad. Sci. U.S.A.
2011, 108, 937-943.

[3] A. Ruditskiy, S.-I. Choi, H.-C. Peng, Y. Xia MRS Bull.
2014, 39, 727-737.

[4] A. Ruditskiy, H. C. Peng, Y. N. Xia Ann. Rev. Chem. Biomol. Eng. Vol 7. 2016, 7, 327-348.

[5] S. Gottesfeld, D. R. Dekel, M. Page, C. Bae, Y. S. Yan, P. Zelenay, Y. S. Kim J. Power Sources. 2018, 375, 170-184.

[6] J. A. Herron, P. Ferrin, M. Mavrikakis J. Phys. Chem. C. 2015, 119, 14692-14701.

[7] A. O. Elnabawy, J. A. Herron, J. Scaranto, M. Mavrikakis J. Electrochem. Soc. 2018, 165, J3109-J3121.
(Invited) Low Temperature Electrolysis for Hydrogen at Scale
Authors: Mukerjee Sanjeev , Kendrick Ian , Doan Huong
Published: February 2020

This presentation will focus on durable, high-performance materials and interfaces for advanced water splitting, enabling a clear pathway for achieving <$2/KgH2 (on scale) with efficiency of 43 KWh/Kg using anion exchange membrane interface. Advances via fundamental understanding of both hydrogen and oxygen evolution reactions (HER/OER) leading to novel materials will be in conjunction with critical improvements in membrane and ionomers and gas evolution electrodes with corresponding characterization and testing. Progress towards these goals under a three-year multifaceted and comprehensive effort will be described wherein Northeastern University (NEU) will present catalyst development and characterization (both in situ and ex situ). University of Delaware (UD) will showcase improvements in ionomer and membrane materials. In addition, close collaboration with National Laboratory partners with Lawrence Berkeley National Lab (LBNL) participating in multiscale modeling and computation in close concert with Sandia National Laboratory (SNL) providing MD simulations of the membrane catalyst interface and National Renewable Energy Laboratory (NREL) providing advanced ionomers, durability protocols and validation will be described.

Anion exchange membrane electrolyzers (AEMELs) are ideally suited with a low-cost profile enabled by platinum group metal (PGM)-free catalysts, low fluorine content membranes, and a less corrosive environment for cell separators. This presentation will showcase state of the art stable, high-conductivity, and high-strength AEMs, stable and active PGM-free catalysts for hydrogen and oxygen evolution reaction (HER/OER), and high performance electrode architectures that together can unlock the cost advantages of AEMELs. If successful, the developed technology can meet FCTO efficiency targets, delivering carbon-neutral hydrogen at $2/kg while simultaneously enabling higher penetrations of wind and PV electricity on the grid.

The overall goal is cell level performance of 1.62 V at 1 A/cm2, which meets the FCTO efficiency target of 43 kWh/kg. Component performance targets have been established using a porous electrode model to support the overall cell performance target. This is at the modeled scale of 50,000 kg/day and operating at 1 A/cm2 resulting in hydrogen cost at $2.15, $1.82, or $1.76/kg, respectively (2, 20, 200 plants). In the low-volume manufacturing case, it is still possible to meet the cost target by operating near 2 A/cm2, sacrificing some efficiency.
(Invited) Anion Exchange Membranes
Authors: Hickner Michael
Published: February 2020

I didn't think I was going to work on anion exchange membranes until Shimshon gave me a call in early 2008 wanting to talk about quaternary ammonium-containing polymers. It has been an interesting journey since then. CellEra's support allowed me to hire my first postdoc - Jingling Yan - and also introduced me to a great cast of characters including Ziv, Dario, John, Yanagi-san, Lin, and the rest. It has been a wild ride and I still remember our dinner in Old Jaffa where I have since eaten with my wife and my parents. I have to thank Shimshon for all of that. It was an interesting time where there was so much excitement and promise in a technology that didn't even work very well. But, Shimshon's vision has really now come true with major federal programs starting in anion exchange membrane fuel cells, dedicated conferences, and some of the highest-impact work in fuel cells now occurring in the orbit of anion technology. Once again, we are following Shimshon. This talk will trace my journey in anion exchange membranes over the last 10 years and show how our thinking has evolved from the early days of chloromethylated poly(sulfone) to our new generation of Ziegler-Natta poly(olefin) anion exchange membranes that show high base resistance and good fuel cell device performance.
(Invited) Progress in Alkaline Membranes and Alkaline Membrane Fuel Cells at the National Renewable Energy Lab
Authors: Neyerlin Ami , Strasser Derek , Antunes C. M. , Meek Kelly , Owczarczyk Zbyslaw R. , Pivovar Bryan S.
Published: February 2020

Alkaline membrane fuel cells are of high interest because they offer the ability to use lower cost catalyst and separator materials: two cost limitations of polymer electrolyte fuel cell systems. The performance advances of these systems has been fairly remarkable as power densities around 2 W/cm2 and current densities above 5 A/cm2 have now been demonstrated.(1) Efforts at NREL have focused on the development of novel ionomers for use in electrodes and membranes. However most of the improvements in performance have arisen due to the impact of electrode fabrication and operating conditions. The different advances that have led to improved performance and durability of these systems as well as remaining challenges will be discussed.

These systems and the results presented are closely tied to the area of alkaline membrane fuel cells where Shimshon Gottesfeld has been an early champion. Beyond the current research portfolio, the presenter for this talk, a former post-doc under Shimshon Gottesfeld will talk about his interactions with Shimshon, with a specific focus on the area of alkaline membrane fuel cells.

References

1. Omasta, T. J. et al. Energy Environ. Sci. 11, 551–558 (2018).
Biochemical Oxygen Demand Microelectrode for Quantifying Concentration Gradients in Anaerobic Biofilms
Authors: Elharati Mohamed A. , Mohamed Abdelrhman , Beyenal Haluk
Published: February 2020

Biochemical oxygen demand (BOD) is one of the widely used parameter to determinate the level of organic pollution in water. The standard method, BOD5 assay, is commonly used to measure BOD concentration but it takes a long time and cannot be integrated for online measurements. Additionally, BOD5 cannot be used to measure BOD in microscale systems, especially in anaerobic biofilms where the oxygen is absent. Because of the limitation of available tools for quantifying BOD concentration within anaerobic biofilms, a new, simple and miniaturized tool is needed for measuring local BOD concentrations in biofilms.

The goal of this work is to develop a BOD microelectrode for quantifying concentration gradients in anaerobic biofilms. The developed BOD microelectrode uses an anaerobic mixed-culture-anodic biofilm as a transducer, which is grown on a carbon fiber tip diameter. The carbon fiber microelectrode acts as the working electrode, which is polarized using a potentiostat. A 100 µm platinum wire counter electrode and a Ag/AgCl-wire pseudo reference electrode are used to complete the electrochemical cell. The BOD microelectrode components are enclosed in a glass outer case. The BOD microelectrodes were calibrated using a standard BOD solution. The performance of the BOD microelectrode was assessed including response time and the linear BOD concentration range. Finally, concentration profiles in an anaerobic biofilm were measured to demonstrate its use.
Highly Specific Detection of Oxytocin in Saliva
Authors: Rana Muhit , Weber Andrew , Manoukian Mourad , Dweik Badawi , Argun Avni
Published: February 2020

Oxytocin is a nine amino acid peptide hormone secreted in hypothalamus that is best known for its significant role in stimulating labor and milk ejection throughout the course of child birth and breastfeeding. As an inducer, oxytocin is used in more than 13 percent of child births in the United States. It is also a neurotransmitter that mediates the dynamic function of the brain and a variety of complex social behaviors including affiliation, sexual behavior, social recognition, and aggression. A similarly structured vasopressin hormone is secreted from the same region in hypothalamus and often competes with oxytocin to bind to existing antibodies. This results in poor specificity and major cross-reactivity issues for the existing oxytocin immunoassays. Mass spectrometry methods combined with liquid chromatography resolve these issues; however, high costs of sophisticated instrumentation, lengthy retention times, and the need for skilled technicians limit their suitability for point-of-care operation.

We present here an aptamer-based electrochemical assay for real-time and point-of-care detection of oxytocin in non-invasive clinical samples such as saliva to allow perinatal monitoring of oxytocin during child birth. Our approach provides highly sensitive and specific detection at low cost through the use of disposable electrodes. Our optimized antibody alternative aptamer has been developed, characterized, and validated as a proof-of-concept oxytocin binder and incorporated to commercially available screen printed electrodes (SPEs). We have developed a method that is specific to aptamer-bound oxytocin to generate signal as electrochemical readout. Our preliminary results confirm that our aptamer-based assay can detect as low as 10 pg/mL (~10 picomolar) oxytocin in saliva samples in less than 5 minutes with minimal false positive or false negative signals.
Electrochemical Reduction of Acetochlor at Carbon and Silver Cathodes in Dimethylformamide
Authors: Couto Petro Ana G. , Peters Dennis G
Published: February 2020

Chloroacetamides are a popular class of herbicides often used against weeds in a variety of major crops, such as corn, cotton, rice, and soybeans.1 One such herbicide is acetochlor or 2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide that, since its registration in 1994, has become commonly used in the United States.2 Although acute and chronic toxicological effects in humans of acetochlor at low environmental exposures are still unknown, animal tests have shown in some species the development of lung tumors, nasal epithelia, and thyroid cancer; for that reason, the U.S. EPA classifies acetochlor as likely to be carcinogenic in humans.3,4 This project’s primary objective is to investigate the electrochemical behavior of acetochlor and to develop a possible degradation method for acetochlor as well as other chloroacetamide-type herbicides.

To the best of our knowledge, previous electrochemical studies of acetochlor have been performed only via anodic Fenton treatment;5 electrochemical reduction has not yet been pursued. In the present study, we have conducted cyclic voltammetry to evaluate the electrochemical behavior of acetochlor at carbon and silver cathodes in dimethylformamide (DMF) containing 0.05 M tetramethylammonium tetrafluoroborate (TMABF4). Glassy carbon is a traditional electrode material and silver has been shown to be catalytic for the cleavage of carbon–halogen bonds. Reduction of acetochlor at silver (–0.95 V vs. Cd/Hg) occurs at more positive potentials than at carbon (–1.4 V vs. Cd/Hg) and affords primarily the dechlorinated parent compound, N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide. In addition, reduction of acetochlor in the presence of electrogenerated nickel(I) salen (–0.95 V vs. Cd/Hg) indicates that nickel salen complexes can be an alternative to silver in order to achieve catalytic reduction. Controlled-potential (bulk) electrolysis coupled with traditional analytical methods such as gas chromatography–mass spectrometry (GC–MS) led to the identification and quantitation of reduction products.

References

Lamberth, C. Chloroacetamide Herbicides. In Bioactive Carboxylic Compound Classes, Pharmaceuticals and Agrochemicals, Lamberth, C., Dinges, J., Eds.; Wiley: Germany, 2016; pp 293–302.

Lerro, C. C.; Koutros, S.; Andreotti, G.; Hines, C. J.; Blair, A; Lubin, J.; Ma, X.; Zhang, Y.; Beane Freeman, L. E. Int. J. Cancer.
2015, 137, 1167–1175.

U.S. Environmental Protection Agency. Acetochlor (Harness) Pesticide Petition Filing 1/00. Fed Regist.
2000, 65, 3682–3690.

Report of the Food Quality Protection Act (FQPA) Tolerance Reassessment Progress and Risk Management Decision (TRED) for Acetochlor. EPA 738-R-00-009; U.S. Environmental Protection Agency (U.S. EPA): 2006, 1–9.

Friedman, C. L.; Lemley, A. T.; Hay, A. J. Agric. Food Chem.
2006, 54, 2640–2651.
NADPH As a Sole Reducing Agent for Silver Nanoparticle Formation - TEM and Electrochemical Insight at the Ensemble and Single Entity Level
Authors: Hietzschold Sebastian , Walter Andrew , Davis Connor , Taylor Aidan , Sepunaru Lior
Published: February 2020

The ability of biomolecules to reduce metal salts to nanoparticles has been repeatedly demonstrated. However, the underlying mechanism of the occurring redox reaction is still vague. We present our recent results, demonstrating that NADPH, a major redox shuttle in organisms, can solely serve as a reducing agent, leading to the formation of monodispersed silver nanoparticles. We further show that this process does not depend on enzymatic catalysis which is the currently accepted route for biological synthesis of nanoparticles. We support our results with UV-vis spectroscopy, TEM images and electrochemical measurements at the ensemble and single entity level.
Crosslinkable Nitroxide Radical Polymer for Energy Storage Applications
Authors: Wang Shaoyang , Easley Alexandra Danielle , Li Fei , Lutkenhaus Jodie L.
Published: February 2020

Due to the amount of waste generated by lithium ion batteries (LIB) disposal, a more environmentally friendly option such as organic batteries, is desired to fulfill the need of this large market. For many years, alternatives to LIBs have been researched, including the use of conductive polymers for completely organic batteries. Redox-active polymers, such as conjugated polyaniline and organic radical poly(2,2,6,6-tetramethylpiperidinyloxy-4-ylmethacrylate) (PTMA), are being studied as electrode materials for organic batteries. As linear PTMA may dissolve in the electrolyte solution and thus degrade battery capacity, crosslinked PTMA is gaining interest as a cathode material. A balance must be struck, however, as diffusion of the electrolyte solution into the polymer may become limited at sufficiently high crosslink density. To balance these competing mechanisms, a random copolymer consisting of PTMA monomer and glycidyl methacrylate (GMA), a UV and thermally crosslinkable monomer, is synthesized (P(TMA-GMA)) and the mechanism of redox activity is studied.

This new PTMA copolymer is synthesized using free radical chain-growth polymerization and is then oxidized to produce the characteristic organic radical. Linear P(TMA-GMA) is characterized using UV-VIS, NMR spectroscopy, and gel permeation chromatography. The effect of crosslinking on the thermal properties and the temperature for thermally induced crosslinking is analyzed using differential scanning calorimetry. The crosslink density is calculated for each composition using the linear P(TMA-GMA) molecular weight and solvent uptake of the crosslinked P(TMA-GMA). Determining the most favored crosslink density is necessary for balancing electrolyte diffusion with the dissolution of the polymer. The electrochemical properties of the crosslinked P(TMA-GMA) is studied using cyclic voltammetry (CV) to determine if crosslinking impacts the redox properties.

Preliminary results have found that the crosslinked P(TMA-GMA) exhibits a change in the shape of the CV curve and peak heights, associated with some change in the crosslinked polymers electroactivity. In addition, the crosslink density of the P(TMA-GMA) with 5 mol% GMA is quantified and is similar to previous studies of poly(ethylene glycol). Finally, the thermal properties are represented by a glass transition temperature that did not significantly change with varying GMA content. This new P(TMA-GMA) shows promise for application in organic batteries by providing a processable yet crosslinkable alternative to PTMA.
Holey Bismuth for Selective Electrochmical CO2 Reduction
Authors: Yang Chih-Wen , Huang Kuo-Wei , Tung Vincent , Zhong Shenghong , Yang Xiulin
Published: February 2020

Because of the consumption of fossil fuel, CO2 emission, a product of burning fossil fuel, causes the global warming. Electrochemical CO2 reduction reaction (eCO2RR) provides a solution that allows to reduce the carbon emission and produce useful products. Among those CO2 reduction products, formic acid is one of the most attractive candidates because it has higher volumetric capacity of H2 (53 g H2/L) and can release H2 by catalyst under room temperature, which makes it a promising energy carrier.[1] Also, it is feasible to transport since it is nonflammable and stable under room temperature. Among the materials for eCO2RR, bismuth has better selectivity toward formate production (Faraday efficiency > 80%).[2]

However, production rate, partial current density toward formate, of those catalyst remained low. One of the approach to boost the production rate is to increase the surface area of catalyst. By creating the porous structure, surface area of catalyst will be increased and thus enhances the production rate of formate. In this work, we successfully synthesized sponge-liked bismuth by chemical vapor deposition (CVD) method for eCO2RR. As results, it shows an excellent current density (28 mA/cm2) and faraday efficiency toward formate (95%) in moderate applied potential -1.05 V (vs. reversible hydrogen electrode (RHE)) under low catalyst loading. Furthermore, Comparing to electroplating bismuth, sponge-liked bismuth have double current density under same electroactive surface area.

[1] Eppinger, J. and K.W. Huang, Formic Acid as a Hydrogen Energy Carrier
. Acs Energy Letters, 2017. 2(1): p. 188-195.

[2] Larrazabal, G.O., A.J. Martin, and J. Perez-Ramirez, Building Blocks for High Performance in Electrocatalytic CO2 Reduction: Materials, Optimization Strategies, and Device Engineering. J Phys Chem Lett, 2017. 8(16): p. 3933-3944.
Fabrication of Metamaterial Building Blocks with Selective Photoreduction of Metal Ions Followed By Electroless Plating Onto DNA Origami Templates
Authors: Hossen Md Mir , Bendickson Lee , E Palo Pierre , Nilsen-Hamilton Marit , Hillier Andrew Campion
Published: February 2020

There is a growing interest in using DNA origami templates to make complex and unique nanostructures which can be used in many applications such as in optical metamaterial fabrication. The unique properties of DNA make it possible to overcome the limitations of the top-down processes such as lithography-based techniques to create metamaterial building blocks for optical frequency. In this report, we have demonstrated a photochemical metallization technique to coat DNA origami structures with a thin layer of silver in solution as well as when supported on a surface. The uniformly coated DNA was further enhanced to a higher thickness using electroless deposition of gold. Triangular and U-shaped DNA origami structures served as photosensitizers in the presence of UV light (365 nm wavelength) to reduce the silver ions from the bulk solution onto the origami surfaces. The photochemical metallization was shown to coat the DNA uniformly with metallic silver following the conformal structure of DNA triangles and Us. Repeating photoreduction steps on the same DNA resulted in increasing silver thickness to a self-limiting value of ~5 nm, after which a selective electroless gold deposition technique was performed to gain an additional 15-20 nm in height. The photochemical silver coating technique preserved the overall structure of the DNA template, though the effective dimension of the triangles and Us were slightly reduced. The light-induced self-limiting silver deposition exhibits a defect filling growth on DNA, which facilitates the uniform enhancement of gold to a higher thickness while mapping the original shape of the DNA template. This two-step metallization technique provides a foundation to create an array of metal nanostructures using DNA origami templates to fabricate metamaterials.
(Physical and Analytical Electrochemistry Division David C. Grahame Award Address) Electroanalytical Techniques for Studying Nitrogenase Enzyme Mechanisms
Authors: Minteer Shelley D.
Published: February 2020

Nitrogenase is the only enzyme known to reduce nitrogen to ammonia. This intriguing enzyme is typically studied spectroscopically and due to the complexity of the nitrogenase system (including the dynamics of both a catalytic protein containing a FeMo-cofactor and an Fe protein), it is hard to directly study enzyme mechanism with standard spectroscopic techniques. This talk will discuss electroanalytical techniques for studying the enzyme mechanism of nitrogenase, including mediated bioelectrocatalysis and direct bioelectrocatalysis. The talk will discuss materials innovation for interfacing these complex proteins with electrode surfaces as well as the use of square wave voltammetry and amperometric titrations to evaluate mechanism, including inhibition studies, mutant enzyme studies, and kinetic isotope effect studies.
(Invited) Current Understanding and Future Aspects of Direct Electron Transfer Mechanism of Fad Dependent Glucose Dehydrogenase Complex
Authors: Sode Koji
Published: February 2020

Direct electron transfer (DET) between enzyme molecule and electrode provides the ideal principle for the enzyme based sensing system. In DET principle the electrons are transferred from enzyme active site to electrode directly in the absence of any additional electron acceptors, or mediators. This intriguing reaction is useful for various biodevices such as biosensors and biofuel-cells, especially by focusing anodic reactions, such as the oxidation of glucose, fructose, and ethanol. The absence of redox mediators in the system enables the operation of the sensor in redox potential closer to the co-factor in the enzyme, reducing the effect of interfering reactions by electroactive compounds in the sample. However, only a limited number of redox enzymes are capable of DET-reaction with electrodes. Among these, several dehydrogenases harboring a redox center in the catalytic subunit/domain and haem which is not involved in catalysis but act as a built-in mediator for electron transfer between enzyme and electrode are reported. One of the representative groups of DET enzymes is the oligomeric dehydrogenases composed of catalytic subunit harboring FAD as a co-factor, and an electron transfer subunit with haem c, the FAD dependent dehydrogenase complexes. Our research group have been engaged in the isolation, characterization, application and engineering of one of the representative FAD-dependent dehydrogenase complexes. FAD glucose dehydrogenase complex (FADGDH). FADGDH is comprised the three distinct subunits: the catalytic subunit (α subunit) that has an FAD cofactor in its redox center, shows catalytic activity, and oxidizes the first hydroxyl group of glucose; the small subunit (γ subunit), a hitch-hiker protein of the bacterial TAT secretion system, which is necessary for the proper folding and secretion of the α subunit; and the three heme-cytochrome c subunit (β subunit) that is in responsible for the transfer of electrons between the active-site cofactor and external electron acceptors. Thanks to the presence of β subunit, FADGDH is capable to transfer electrons directly to an electrode, making FADGDH as the ideal molecule for the 3rd Gen glucose sensors.

This paper focuses on biomolecular aspects on DET mechanism of FAD dependent dehydrogenase complexes, considering current increasing number of applicational researches, and recent remarkable progress in understanding their DET mechanism, especially about the recent progress in understanding inter- and intra-molecular electron transfer of FADGDH are introduced. These studies included protein engineering approaches of these molecules, thereby led to construct engineered GDH. Finally, the future prospect of the FAD dependent dehydrogenase complexes will be addressed.
Photoelectrochemical Biosensing
Authors: Tang Jing
Published: February 2020

Photoelectrochemical sensing represents a unique means for chemical and biological detection, with foci of optimizing semiconductor composition and electronic structures, surface functionalization layers, and chemical detection methods. Here, we have briefly discussed our recent developments of nanowire‐based photoelectrochemical sensing, with particular emphasis on three main detection mechanisms and corresponding examples. We have also demonstrated the use of the photoelectrochemical sensing of real‐time molecular reaction kinetic measurements, as well as direct interfacing of living cells and probing of cellular functions.

Figure 1
Electrochemical Cell with Electrolyte Flow Enables Operando ATR-IR Spectroscopy of Electrocatalytic CO2 Reduction through Control of Mass Transport
Authors: Lin John Christopher , Aviles Acosta Jaime E , Hahn Christopher , Jaramillo Thomas F
Published: February 2020

The efficient electrocatalytic conversion of abundant species such as water, carbon dioxide, and nitrogen to fuels and chemicals with renewable energy could provide a sustainable alternative to fossil fuels and thus mitigate climate change. To develop better electrocatalysts for reactions such as electrochemical CO2 reduction (CO2R), it is desirable to probe the electrode-electrolyte interface spectroscopically while also measuring intrinsic reaction rates that are not affected by concentration polarization. Infrared absorption spectroscopy in the Kretschmann attenuated total reflection mode (ATR-IR) provides such interfacial sensitivity, especially when the working electrode’s morphology and thickness are optimized to maximize surface-enhanced IR absorption (ATR-SEIRAS). Here, we address a persistent challenge – i.e., collecting operando vibrational spectra while measuring intrinsic electrochemical reaction rates – by designing and evaluating a new electrochemical cell for ATR-IR studies. The parallel orientation of the electrodes in the cell yields a more uniform current distribution, and the convective flow of electrolyte both removes bubbles and provides the control over mass transport that is essential to avoid concentration polarization. The membrane between the working and counter electrodes allows for quantitative product detection. We evaluated the cell’s transport properties with a reversible redox reaction, and we used it to collect operando vibrational spectra during CO2R with Au working electrodes. We found that electrolyte flow both determined the boundary layer thickness and effectively removed bubbles, and that the measured current densities and product selectivity were consistent with the known CO2R activity of Au. In light of these results, this new cell design for operando electrochemical ATR-IR spectroscopy should improve the link between vibrational spectra and intrinsic reaction rates and thereby provide valuable mechanistic insights for CO2R and other reactions in electrocatalysis.
Operando Observation of Cobalt Catalysts for Water Splitting By X-Ray and Infrared Absorption Spectroscopy
Authors: Yamada Kanta , Sakata Yoshihisa , Yoshida Masaaki
Published: February 2020

Recently, electrochemical hydrogen production by water splitting has been receiving attention with regard to achieving a sustainable society. For commercial applications, improving overall water splitting efficiency has been required for the development of highly active oxygen evolution electrocatalysts. In this situation, Nocera and colleagues reported that a cobalt oxide electrodeposited from a dilute Co2+ solution in a potassium phosphate buffered electrolyte (Co-KPi) is efficient electrocatalyst for oxygen evolution reaction (OER) [1]. The local structure of Co species in the Co-KPi catalyst was investigated by Co K-edge X-ray absorption fine structure (XAFS) spectroscopy and X-ray pair distribution function (PDF) analysis, and it was revealed that the Co-KPi is composed of nano-sized clusters with an edge-sharing CoO6 octahedral structure [2]. However, the detailed information about oxygen species in this electrocatalyst under working condition is not yet obtained enough.

In this situation, we have developed many operando observation techniques for XAFS and infrared absorption spectroscopy using attenuated total reflection mode (ATR-IR) to observe the oxygen evolution electrocatalysts. For example, hard X-ray XAFS can observe the electronic states and local structures of metal species in the catalysts. On the other hand, tender and soft X-ray XAFS and ATR-IR can reveal the chemical states of light elements in the catalysts. Therefore, we investigated the reaction mechanism of Co-KPi and similar catalysts for water splitting using various kinds of operando XAS and ATR-IR spectroscopy (Figure 1).

At first, we prepared for Co-KPi and some similar cobalt catalysts in a potassium acetate (Co-KOAc) or a potassium chloride (Co-KCl) aqueous solution by electrodeposition method. It was confirmed that these cobalt catalysts are composed of the edge-sharing CoO6 octahedral structure (CoOOH) by Co K-edge XAFS using hard X-ray. Next, operando O K-edge XAFS spectra for cobalt catalysts were taken using soft X-ray under electrochemical control. When the electrode potential was changed from 0.0 to 1.1 V, a new absorption peak assigned to oxygen species of CoO2 was observed around 529 eV, indicating that the part of CoOOH cluster was oxidized to CoO2 with the high-valent cobalt species (Co4+). The CoO2 peak was obviously observed for Co-KPi of highly active OER electrocatalyst, compared with Co-KOAc and Co-KCl. Finally, operando P K-edge XAFS and ATR-IR revealed the phosphate ion is bounded on the cobalt clusters to stabilize the CoO2 structure. Therefore, we revealed that Co-KPi can function as highly active OER electrocatalyst due to the presence of CoO2 strucutre stabilized by phosphate ion.

[1] D. G. Nocera et al, J. Am. Chem. Soc. 131, 2615 (2009).

[2] (a) D. G. Nocera et al, J. Am. Chem. Soc. 132, 13692 (2010). (b) J. Am. Chem. Soc. 135, 6403 (2013).

Figure 1