bluuebunny/crossref_metadata_2025 huggingface dataset:
Tailoring the Coefficient of Chemical Expansion in Perovskite Oxides through A Vs. B-Site Multivalent Cation Placement
Authors: Anderson Lawrence O , Perry Nicola H.
Published: May 2020

Chemical expansion is a strain induced by a change in stoichiometry, such as oxygen loss. It can enable a material to actuate when exposed to different gas environments, and it can significantly impact device longevity when there are large concentration gradients across small material dimensions in multilayer devices. The desired magnitude of chemical expansion depends on the application; typically, the goal is a large expansion in the former and a small expansion in the latter, where compatibility with neighboring materials is of concern. Therefore, design rules for tailoring expansion from oxygen exchange are needed for the multitude of applications in which it is a contributing factor.

As oxygen leaves an oxide lattice during reduction, electrons are generated to preserve charge neutrality, which may move to multivalent cations; this process results in significant expansion of the multivalent cation, and the surrounding lattice, as the oxidation state of the multivalent cation decreases. Recently, an empirical formula describing the pseudo-cubic lattice constant of perovskite materials was developed [1], which relates the lattice parameter to the ionic radii of each cationic and anionic component. This equation predicts that changes in the B-site cation size will have a larger effect on the lattice parameter than an equal change at the A-site. If the multivalent cation is the only one changing size during redox processes, this equation suggests that its placement on the A or B site will have a significant effect on the magnitude of the overall lattice strain during oxygen loss or gain.

To test this theory, model perovskite bulk ceramic compositions with multivalent Pr(3+,4+) on the A site and on the B site were fabricated: PrGa0.9Mg0.1O2.95+
δ and BaPr0.9Y0.1O2.95-
δ, respectively. Strain values from dilatometry and defect concentrations from thermogravimetric analysis were used to calculate the coefficients of chemical expansion (CCE) in both materials, to determine the effect of multivalent cation placement. These measurements were performed under isothermal conditions while varying the pO2 to avoid effects from nonuniform thermal expansion at different stoichiometries. Multiple temperatures were analyzed to observe any temperature-related trends in CCEs and to determine any effects from crystal structure changes. The resulting CCEs will be interpreted not only in terms of multivalent A vs. B site placement but also considering other factors that may impact CCEs: crystallographic distortions, temperature, and charge localization.

[1] Marrocchelli, D., Perry, N. H., & Bishop, S. R. (2015). Understanding chemical expansion in perovskite-structured oxides. Physical Chemistry Chemical Physics, 17(15), 10028-10039.
Mechano-Electrochemistry – Towards Structural Batteries and Energy Harvesters
Authors: Muralidharan Nitin , Pint Cary L.
Published: May 2020

Lithium ion batteries have revolutionized our modern society and have catalyzed the growth of advanced technologies such as electric vehicles and portable electronic devices. Batteries are dynamic mechano-electrochemical systems where the components and interfaces are subjected to significant mechanical stresses and strains during operation. Most current research approaches discard the coupled mechanical processes as an unavoidable byproduct. However, the coupling between mechanics and electrochemistry, mechano-electrochemical coupling, is a powerful yet unexplored tool. In this regard, our research efforts so far have been aimed at understanding and isolating this fundamental phenomenon followed by developing new classes of energy devices that leverage these findings for several unique applications. First, using principles of elastic strain engineering, we have demonstrated controllable modulation of electrochemical parameters governing energy storage systems as a function of applied strain. Next, building off these findings, we developed electrochemical-mechanical energy harvesters for harnessing ambient mechanical energy at very low frequencies (<5 Hz), a regime where the conventional state of the art piezoelectric and triboelectric energy harvesters have drastically reduced performances. The unique frequency tuning capabilities in this class of energy harvesters enable development of devices for use in human motion harvesting/sensing applications and multifunctional transient energy harvesting/storage devices. Additionally, to further understand the relationship between mechanical and electrochemical properties, we developed multifunctional structural supercapacitor and ultra-battery composites for use in load-bearing applications. Overall, our findings provide a broad framework for using mechano-electrochemistry as a design tool for developing next generation energy storage devices.

References:

[1] Energy harvesting devices and methods of making and use thereof. CL Pint, N Muralidharan - US Patent App. 16/058,046, 2019

[2] A Fully Transient Mechanical Energy Harvester. N Muralidharan, J Afolabi, K Share, M Li, CL Pint - Advanced Materials Technologies, 2018

[3] Mechano-Electrochemistry for Advanced Energy Storage and Harvesting Devices. N Muralidharan - 2018

[4] Ultralow Frequency Electrochemical–Mechanical Strain Energy Harvester Using 2D Black Phosphorus Nanosheets. N Muralidharan, M Li, RE Carter, N Galioto, CL Pint - ACS Energy Letters, 2017
(Invited) Optimal Morphology of Cu-Based Catalyst for Efficient Electrochemical Synthesis of NH3 By Direct Reduction of N2 and H2o at Ambient Conditions
Authors: Kani Nishithan C , Singh Meenesh R
Published: May 2020

The electrochemical synthesis of ammonia (NH3) by direct reduction of N2 in an aqueous medium under ambient conditions is a sustainable alternative to the energy intensive Haber-Bosch process. The major challenges in the electrochemical synthesis of NH3 are due to lower yield, lower faradaic efficiency (FE), and higher H2 production. To overcome these issues, an efficient and selective electrocatalyst that promotes nitrogen reduction reaction (NRR) and suppresses hydrogen evolution reaction (HER) is required. Here we show polycrystalline Cu is an active catalyst for NRR and it also suppresses H2 formation at lower overpotentials. The objective of this study is to evaluate the effect different morphological forms of Cu such as planar, nanoparticles, nanowires, nanocubes, and porous foam on the activity and FE of NH3. These catalysts are supported on a carbon-based gas diffusion electrode (GDE) and evaluated in a flow-through electrochemical cell for effective mass-transfer of N2. The gaseous product- H2 is quantified using in situ gas chromatography and the liquid product- NH3 is quantified using Nessler’s reagent. The FE and yield of NH3 for Cu-based catalysts are comparable to Fe-based and other noble metal-based catalysts. The optimal Cu-based catalyst structure and electrolyte composition will be presented for electrochemical synthesis of NH3.
(Invited) Discussion on Use of Controls and Quantitative Verification of Electrochemical Ammonia Production
Authors: Greenlee Lauren Fay
Published: May 2020

The research community focused on the development of heterogeneous electrocatalysts for low temperature electrochemical nitrogen reduction to ammonia continues to see an increasing number of publication contributions on electrocatalyst synthesis and performance testing, with few studies conducting quantitative and thorough verification of ammonia production data. With the recent publication of recommended guidelines and procedures for controls and isotopic verification of ammonia synthesis, we need to continue to discuss as a research community what is necessary to support electrocatalyst design and synthesis efforts. Some open questions for continued discussion include: What level of experimental controls and isotopic quantification are necessary, and how should these experiments and results be reported? Are we missing ambient or contaminant influences in our ammonia measurements? What studies published thus far represent the highest quality of work, and should these studies be used to demonstrate electrocatalyst design pathways? How can we promote and proceed with repeating published work to verify electrocatalyst performance? What are the experimental challenges that researchers are facing in being able to repeatedly and accurately measure ammonia produced by heterogeneous electrocatalyst surfaces? In this talk, we will discuss these and other questions facing our NRR research community today.
Influence of Surface Chemistry of Iron-Nickel Oxide Films on Ammonia Synthesis and Hydrogen Production
Authors: Bakovic Sergio I. Perez , Renner Julie N. , Janik Michael J. , Greenlee Lauren Fay
Published: May 2020

The Faradaic efficiency limitation of electrocatalyst surfaces for low temperature nitrogen reduction to ammonia in aqueous electrolytes is driven by a dominance of the hydrogen evolution reaction (HER). To address and reduce the dominance of the HER on electrocatalyst surfaces, along with maintaining electrocatalyst activity toward the nitrogen reduction reaction (NRR), control of both the electrocatalyst surface and the electrolyte interface chemistry are likely necessary. In this work, we study how the surface chemistry of a suite of iron-nickel oxide electrocatalysts changes upon exposure to the NRR electrocatalytic environment and as a function of as-synthesized chemical structure. In addition, we study how an electrolyte interface functional layer influences both electrocatalyst surface chemistry and resulting electrocatalytic behavior toward the HER and the NRR. Characterization focuses on the use of traditional ultra-high vacuum and ambient pressure x-ray photoelectron spectroscopy (XPS) experiments to understand the details of as-synthesized, post-electrochemistry, and ambient exposure (i.e., water vapor and argon/nitrogen gas exposed) surface chemistry of the iron-nickel oxide films. A discussion of our experimental results will include an analysis of how surface composition, metal component oxidation state, electrolyte components, and water/hydroxyl surface adsorption change as a function of starting film composition and ambient exposure conditions.
(Invited) Intermediate Temperature Direct Ammonia Fuel Cell Using Alkaline Electrolyte System
Authors: Lattimer Judith , Patil Kailash , McCatty Steve , Mohan Yamini , Butler Katie , Xu Hui
Published: May 2020

Ammonia is a very attractive carbon-neutral fuel due to its low cost, high energy density, and existing transportation infrastructure. However, the viable commercial application of direct ammonia fuel cells (DAFC) has not been realized, largely due to materials challenges. Generally, DAFCs either use low temperature polymer electrolytes, which are limited by low reaction rates, or use high temperature solid oxide electrolytes, which suffer from severe material thermal degradation. We have developed an intermediate temperature alkaline electrolyte-based DAFC that operates at 400-600 °C, enabling high reaction rates while limiting thermal degradation. This DAFC is based on our innovative molten hydroxide electrolyte impregnated in a porous ceramic matrix, which has conductivity as high as 0.4 S/cm at 350 °C, enabling rapid hydroxide transport. The DAFCs use state-of-the-art ammonia oxidation catalysts and ammonia-tolerant ORR catalysts developed in-house and by our collaborators at SUNY Buffalo and University of Delaware. Our DAFC has demonstrated an OCV of 1.2 V and can achieve 300 mA/cm2 at 0.86 V, or >250 mW/cm2 power from pure humidified ammonia. It is stable for days without loss of activity and has very low ammonia crossover, enabling the high OCV and high power density without catalyst poisoning. Further work on catalyst development and cell design is underway to achieve higher power densities and reduce PGM catalyst loading and operation temperature, making this a more commercially viable technology.

Acknowledgements: This work is financially supported by the Department of Energy’s ARPA-E under the award# DE_AR000814
(Invited) Two Phase Flow in Porous Transport Layer Structures in Polymer Electrolyte Water Electrolysis
Authors: De Angelis Salvatore , Schuler Tobias , Schmidt Thomas J. , Büchi Felix N.
Published: May 2020

In polymer electrolyte water electrolysis (PEWE), mass transport losses are the least understood overvoltage contribution. Underlying origin as well as correlation parameters with the micro-structure of the porous transport layer (PTL) are not identified. X-ray imaging has the potential to clarify the relation between oxygen transport and mass transport losses, but in the highly absorbing titanium porous structures the contrast between water and gas is weak. Therefore, imaging parameters need to be carefully tuned to identify the two phases.

Using synchrotron light, X-ray tomographic microscopy was applied to study ex-situ and operando PEWE cells and the two-phase flow in the PTL (see image and rendering in Figure 1) and at the interface1,2 to the catalyst layer was observed. The combination of electrochemical characterization with X-ray imaging leads to better understanding of the controlling parameters and the related mass transport losses.

References

1. T. Schuler, R. De Bruycker, T.J. Schmidt and F.N. Büchi, Journal of The Electrochemical Society, 2019, 166, F270-F281.

2. T. Schuler, J.M. Ciccone, B. Krentscher, F. Marone, C. Peter, T.J. Schmidt and F.N. Büchi, Advanced
Energy Materials, 2019, 1903216

Figure 1
Anodic Oxidation of Bisamides
Authors: Becker James Y.
Published: May 2020

Previously [1] we studied the anodic oxidation of bisamides of type RCONH(CH2)nNHCOR (n = 2-4) under controlled current electrolysis (CCE), in methanol. Those with 3 and 4 methylene groups undergo mostly mono- and dimethoxylation at the alpha-position to 'N' atom. However, when the spacer contains two methylene groups only the anodic process favor fragmentation products due to CH2-CH2 bond cleavage, as shown in Eq. 1.

Following the above results, the anodic oxidation of aromatic bisamides with ‘CH2CH2’ as a spacer (ArCONHCH2CH2NHCOAr), has been investigated [2] in acetonitrile, and under controlled potential electrolysis. The outcome indicates that the major products involve unsymmetrical geminal bisamides (Eq. 2) that are difficult to synthesize by other methods.

References

[1] T. Golub and J.Y. Becker, Beilstein J. Org. Chem.
2018,
14, 861–868.

[2] T. Golub, G.-Y. Dou, C.-C. Zeng and J. Y. Becker, Org. Lett., 2019, 21,

7961-7964 [DOI: 10.1021/acs.orglett.9b02917].

Figure 1
Electrochemical Total Synthesis of Pratosine By Controlling for the Anodically Initiated One-/Two-Electron Transfer Process
Authors: Okamoto Kazuhiro , Chiba Kazuhiro
Published: May 2020

Pratosine is a type of a pyrrolophenanthridone alkaloid that includes indole ring and electron donating group-substituted N-benzoyl moiety. Many researchers demonstrated various synthetic reactions to access a simple poly-heterocyclic structure of pyrrolophenanthridone. For instance, intramolecular cyclization between indoline and N-benzoyl moiety was accomplished by stoichiometric Pd-mediated C-H activation1, hypervalent iodine mediated oxidative cross-coupling2 and inverse electron-demand Diels-Alder reaction3. Continuously DDQ oxidation to convert indoline to indole is necessary in all case.

We established electrochemical intramolecular radical cation cross-coupling and indole synthesis reaction. These reaction was initiated by same anodic oxidation for electron-rich benzoyl group, but acid or base additive-dependent different electron-transfer pathway was occurred in both cyclization and indole ring forming reaction.

Reference

(1) DC. Black, PA. Keller, N. Kumar, Tetrahedron Lett.
1989, 30, 5807-5808.

(2) MD. Ganton, MA. Kerr, Org. Lett.
2005, 7, 4777-4779.

(3) DL. Boger, SE. Wolkenberg, J. Org. Chem.
2000, 65, 9120-9124.

Figure 1
Electron-Transfer Driven Cyanation of Aryl Iodides
Authors: Suga Seiji , Yoshioka Kazuki , Hirata Takayuki , Mitsudo Koichi , Midorikawa Koji
Published: May 2020

Aryl cyanides are widely utilized as important intermediates in the research fields of pharmaceuticals, natural products and also organic materials, because the nitrile group can easily be transformed into a wide variety of functional groups, such as amides, carboxylic acids, imines, ketones, and amines. In the preparation of aryl cyanides, Rosenmund–von Braun reaction, in which an aryl halide reacts with copper cyanide, is often used; however, harsh reaction conditions are required, and the separation of cupper complexes in a workup process is often problematic, especially in a large-scale synthesis. We initiated our study to develop a copper free method to prepare aryl cyanides, and found that a catalytic amount of 1,10-phenanthroline nicely promoted the reaction of aryl iodides with tetraethylammonium cyanide to afford aryl cyanides (Scheme 1). 1,10-phenanthroline would work as a SET initiator on the first stage to generate radical anion. We next tried to use the electrochemical reaction for the initiation step. Electricity was simply passed to the mixed solution of aryl iodides and tetraethylammonium cyanide to afford the corresponding aryl cyanides in moderate yields. Notably, the reactions proceeded with a catalytic amount of electricity.

Figure 1
Efficient and Selective Aryl-Nitro Reduction of Pharmaceutical Intermediates
Authors: Graaf Matthew D.
Published: May 2020

Hydrogenation of nitro groups to produce anilines is a well-established transformation in organic chemistry and the pharmaceutical industry [1]. However, high pressure hydrogenations can be hazardous at multi-kilo scales and functional group compatibly is often problematic for pharmaceutical intermediates requiring a specialized catalyst [2]. In a continued effort to promote electrochemistry in pharma as a greener and safer alternative, an improved method of electrochemically producing anilines has been achieved. In this presentation, the development of a robust and efficient undivided Aryl-nitro reduction will be discussed.

References:

[1]: Jones, W.; Platinum Metals Rev., 1958, 2, 86

[2]: Blaser, H-U., Steiner, H., Studer, M.; ChemCatChem., 2009, 1, 210

Figure 1
Study of Xanthates Electrochemical Reactivity and Their Electro-Transformations
Authors: López-Lopez Sergio Jesus , Lopez-Lopez Ernesto Emmanuel , Frontana-Uribe Bernardo A.
Published: May 2020

The generation of free radicals from xanthates has been widely used in the formation of C-C bonds. However, the industrial application use of xanthates has been scarce due to transition metals and peroxides mediated reactions. This work explores the electrochemical reactivity of xanthates in aqueous and anhydrous media, as well as their application as a source of radicals in electrotransformations of the staring materials using direct potentiostatic electrolysis on GC electrode. Additional experiments were carried out in order to study the oxygen/superoxide system as a mediator in the xanthates activation.

Figure 1
Electrocatalytic Semihydrogenation of Alkynes to Z-Alkenes Using a Proton Exchange Membrane Reactor: Influence of Catalyst Materials on Product Selectivity and Reaction Rate
Authors: Atobe Mahito , Nogami Shuji , Minoshima Juri , Fukazawa Atsushi , Nagasawa Kensaku , Mitsushima Shigenori
Published: May 2020

Z-alkenes are versatile building blocks in organic synthesis and often found in pharmaceuticals, perfumes, and natural products. Although a number of methods for stereoselective synthesis of Z-alkene have been developed so far, the Lindlar semihydrogeneation of alkynes is a long-standing synthetic transformation and still remains a privileged system. However, it used toxic Pb additive and a large amount of quinolone, and has other limitations such as narrow substrate scope. Therefore, development of a powerful and reliable system for stereoselective semihydrogenation of alkyne to Z-alkene as alternative to the Lindlar catalytic system is still challenging target.

Under these backgrounds, we have demonstrated electrocatalytic hydrogenation in a proton exchange membrane reactor so called PEM reactor to develop a powerful and reliable stereoselective semihydrogenation system. Especially, in this work, we have investigated systematically influences of catalyst materials such as Pt, Pd, and PtPd alloy for a PEM reactor on the product selectivity for Z-stilbene and partial current density for Z-stilbene formation in the hydrogenation of diphenylacetylene. As a result, PtPd alloy with a composition of 1(Pt):99(Pd) was found to be a most suitable catalyst material in order to achieve both high Z-stilbene selectivity and high partial current density for Z-stilbene formation (Figure 1).

The authors gratefully acknowledge support by JST CREST Grant No. JPMJCR18R1, Japan.

Ref. A. Fukazawa, J. Minoshima, K. Tanaka, Y. Hashimoto, Y. Kobori, Y. Sato, M. Atobe, ACS Sustain. Chem. Eng.
2019, 7, 11050-11055.

Figure 1
Highly Diastereoselective Anodic Fluorination of Organosulfur Compounds Based on Neighboring Participation
Authors: Furuta Shoji , Inagi Shinsuke , Fuchigami Toshio
Published: May 2020

Highly diastereoselective and efficient anodic α-fluorination of phenyl, p-chlorophenyl, and 2-naphthyl 3,3,3-trifluoro-2-methoxypropyl sulfides was successfully carried out at platinum electrodes in Et3N-nHF (n = 3-5)/MeCN to provide the corresponding α-fluorinated products in good yields, whereas the corresponding p-methoxyphenyl sulfide derivative gave much lower diastereoselectivity. On the basis of such marked substituent effects on the diastereoselectivity and a previous study of anodic methoxylation of related sulfides,1) as well as the X-ray analysis of the configuration of the major diastereomer of the electrochemically fluorinated alph-naphthyl derivative, it was clarified that the high diastereoselectivity is attributable to the neighboring MeO group participation to the anodically generated cationic intermediate destabilized by an electron-withdrawing CF3 group.2)

References:

1. M. Isokawa, M. Sano, K. Kubota, K. Suzuki, S. Inagi, and T. Fuchigami, J. Electrochem. Soc., 164, G121 (2017).

2. S. Furuta, S. Inagi, t. Fuchigami, J. Electrochem. Soc., 166, G110 (2019).
Electrochemical Sulfonylation of Electron-Rich Aromatic Substrates with Sodium Sulfinates
Authors: Nikl Joachim , Lips Sebastian , Waldvogel Siegfried R.
Published: May 2020

The use of electricity in organic synthesis is characterized by various advantages over conventional methods in terms of reaction selectivity, safety, and sustainability.[1] The use of electrons as reagents, as well as precise reaction control, allows direct C–H bond activation, resulting in less reagent waste. The combination of supporting electrolyte and coupling component, therefore, has a particularly positive effect on the atomic efficiency. Regarding this, we present an electrochemically driven synthesis of various aryl and diaryl sulfones,[2] which amongst others are an important structural motif in pharmaceutical active ingredients.[3] This electrochemical protocol, based on boron-doped diamond electrodes (BDD) and 1,1,1,3,3,3‐hexafluoropropan‐2‐ol (HFIP) as solvent, leads to a direct C–S coupling of electron-rich aromatic substrates with sodium sulfinates. The last ones are used combinatorially as supporting electrolytes and coupling components, which makes this method a sustainable contribution to the organic synthesis of sulfones.

References

[1] a) H. J. Schäfer, C. R. Chim. 2011, 14, 745– 765; b) A. Wiebe, T. Gieshoff, S. Möhle, E. Rodrigo, M. Zirbes, S. R. Waldvogel, Angew.
Chem. Int. Ed. 2018, 57, 5594– 5619; Angew. Chem. 2018, 130, 5694– 5721.

[2] a) J. Nikl, S. Lips, D. Schollmeyer, R. Franke, S. R. Waldvogel, Chem. – Eur. J.
2019, 25, 6891–6895; b) J. Nikl, D. Ravelli, D. Schollmeyer, S. R. Waldvogel, ChemElectroChem.
2019, 6, 4450–4455.

[3] a) M. Feng, B. Tang, S. H. Liang, X. Jiang, Curr. Top. Med. Chem. 2016, 16, 1200– 1216; b) D. C. Meadows, J. Gervay-Hague, Med. Res.
Rev. 2006, 26, 793– 814.

Figure 1
Electrochemical Intramolecular C–S Bond Formation Leading to Thienoacene Derivatives
Authors: Mitsudo Koichi , Yonezawa Toki , Matsuo Ren , Suga Seiji
Published: May 2020

The formation of carbon-sulfur bond is one of the fundamental and significant transformations in organic synthesis because C-S bonds are abundant and significant skeleton in the field of pharmaceuticals and material science. For instance, thienoacene derivatives, such as [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and dinaphtho[2,3-b:2’,3’-d]thiophene (DNT), have received considerable attention as key building blocks for organic field effect transistors (OFETs).

Recently, several novel methods for the construction of carbon-heteroatom bonds have been reported. In particular, electrochemical C–H activation reactions have received considerable attention as straightforward and attractive approaches for the construction of C–O, C–N, and C–S bonds. However, to the best of our knowledge, there has been no report on the application of the electrochemical C–S bond formation for the synthesis of thienoacene derivatives, although they should be a simple and attractive approach to thienoacene derivatives.

From this perspective, we are focusing on an electrochemical C–S bonds formation for the synthesis of thienoacene derivatives, such as [1]benzothieno[3,2-b]benzo[2,3-d]furan (BTBF) and [1]benzothieno[3,2-b]benzo[2,3-d]thiophene (BTBT). We herein report the first electro-oxidative dehydrogenative C–S bond formation promoted by electrogenerated [Br+] for the synthesis of BTBF and BTBT.

Figure 1
Electrochemistry of Nanoscale Hybrid Materials (NOHM) Complexes
Authors: Zawodzinski Thomas A. , Bruce Maria , Park Ah-Hyung , Hamilton Sara Triana , Cantillo Nelly M.
Published: May 2020

Nanoparticle organic hybrid materials, also known as NOHMs, are composite particles formed by polymers grafted (either ionically or covalently) onto surface-modified inorganic nanoparticles. The unique structure and liquid-like properties of such material have promoted the interest on its application as an electrolyte with the potential to capture and carry nonpolar electroactive species.

In this work two types of NOHMs are considered. Both systems comprise silica cores ionically grafted with polymer tails. The polymer tails correspond to polyethylimine for the NOHM-I-PEI, and to polyetheramine with a sulfonic acid linker for the NOHM-I-HPE.

Cyclic voltammetry was used to investigate the interaction of NOHM-I-PEI and NOHM-HPE with copper. NOHM-I-PEI showed a significant pH influence, with peak inhibition occurring at high pH. The protonation behavior of PEI and NOHM-I-PEI was explored (Figure 1). CV results suggest a strong binding of the copper ions and a potential competition between protons and metal ions. Copper hydroxide formation can also occur at higher pH. In contrast, onset potential shift was observed in presence of NOHM-I-HPE.

These studies are complemented by exploration through Electron Paramagnetic Resonance (EPR) and Nuclear Magnetic Resonance (NMR). Through EPR, the nature of the ion in solution can be explored. On the other hand, 13C T1 relaxation of the NOHM-based electrolyte at different compositions provide information on the dynamics of the grafted polymers in solution

Figure 1
Polymer Brush Made from Ionic Liquid and Its Anti-Biofilm Formation Behaviors By Environmental Biota in a Flow-Type Laboratory Biofilm Reactor
Authors: Kanematsu Hideyuki , Oizumi Atsuya , Sato Takaya , Sato Ryo , Kamijo Toshio , Honma Saika , Hirai Nobumitsu , Kogo Takeshi , Ogawa Akiko , Tsunashima Katsuhiko , Barry Dana M.
Published: May 2020

Biofilms are formed on materials surfaces by bacterial activities, which leads to the many kinds of contaminations and causes many industrial problems such as scale inside cooling water pipes, corrosion, hygiene issues at kitchens, dining, toilets, bath tubs, chronic diseases in medical fronts etc. To solve the industrial problems, many countermeasures have been proposed so far. The approach from the viewpoint of materials is one of the good ways to solve the biofilm problems. In this research, we investigated how biofilm behaviors formed in a flow type laboratory biofilm reactor (Fig.1) were affected by polymer brush coating of ionic liquids. As polymer brush, N-diethyl-N-(2-methacryloylethyl)-N-methylammonium bis(trifluoromethylsulfonyl) imide (ρDEMM-TFSI) was used with PMMA polymer brush coating as control. The polymer brush coated glass specimens were immersed in the laboratory biofilm reactor where environmental bacteria were mixed into water to form biofilms in the reactor. The specimens with biofilms were evaluated by Raman spectroscopy and optical microscopic observations. And the results were compared with those for PMMA polymer brush specimens. The results were also compared with those obtained by static immersion tests. As well as the results by static methods, ρDEMM-TFSI polymer coating specimens were sensitive to biofilm formation, being compared with the results for PMMA polymer brush coating specimens. The reason could be attributed to the ionic (anionic )polarization of ρDEMM-TFSI coating’s surfaces. However, those biofilms seemed to be concentrated at the vicinity of surfaces. Therefore, the biofilms restricted to the surface area might be removed easily.

Figure 1
Scanning Electrochemical Potential Microscopy Imaging Horseradish Peroxidase on HOPG
Authors: Zhang Baohua , Stimming Ulrich
Published: May 2020

Electrochemical scanning tunneling microscopy (EC-STM) has been successfully applied to study the electron-transfer (ET) reactions of biomolecules at solid-liquid interfaces.1–4 However, there are still limitations, including requirement of sample conductivity and potential damage to the biomolecules from strong tunneling current, to be overcome.

A different type of probe microscopy, scanning electrochemical potential microscopy (SECPM), can be used as a promising alternative. SECPM shares the similar hardware setup with EC-STM, except for the current amplifier being substituted by a potentiometer to measure the local electrochemical potential as feedback signal. This feature enables SECPM to work on less conductive biomolecular samples. It has been shown that SECPM is capable of imaging horseradish peroxidase (HRP) at single molecular level under in situ conditions, with image resolution comparable or even better than EC-STM (Figure 1). 5

The electrochemical double layer (EDL) existing at the solid-liquid interface in an electrochemical cell can be investigated by SECPM using tip-distance curves. Preliminary results will be shown.

In this work, we use SECPM to image HRP molecules adsorbed on HOPG under in situ conditions, with varying electrochemical potentials applied to the substrate. HRP redox reactions were controlled by varying the substrate potential, and the corresponding change of the potential distribution in the EDL covering the adsorbed HRP surface was recorded by SECPM. The experimental results could offer a novel perspective to understand how the ET reactions influences the EDL, and then help the further research on biosensors and EDL capacitors.

This work is supported in part by the North-East Centre for Energy Materials (EP/R021503/1) funded by EPSRC.

References:

1. E. P. Friis et al., Proc. Natl. Acad. Sci., 96, 1379–1384 (1999)

2. Q. Chi, O. Farver, and J. Ulstrup, Proc. Natl. Acad. Sci., 102, 16203–16208 (2005)

3. M. Wang, S. Bugarski, and U. Stimming, Small, 4, 1110–1114 (2008)

4. M. Wang, S. Bugarski, and U. Stimming, J. Phys. Chem. C, 112, 5165–5173 (2008)

5. C. Baier and U. Stimming, Angew. Chemie - Int. Ed., 48, 5542–5544 (2009)

Figure 1
Electron Transfer at Photosystem I - Electrode Interfaces: Porous & Translucent Indium Tin Oxide Cathodes
Authors: Wolfe Kody , Dervishogullari Dilek , Stachurski Christopher , Passantino Joshua , Jennings G. Kane , Cliffel David E.
Published: May 2020

Biohybrid photovoltaics leverage naturally occurring photo-active protein complexes to convert solar energy into electricity; offering a unique route to lowering the cost and environmental impact of solar energy conversion. Photosystem I (PSI), a protein complex found in higher plants, algae, and cyanobacteria, produces photoexcited excitons over a distance of approximately 10 nm with a 1.1 V photopotential. PSI has been utilized in a variety of biohybrid photovoltaics with success; however, improvements in performance are necessary to bring PSI – based devices to a technologically viable state. The electrons and holes produced within a PSI biohybrid photovoltaic must pass through multiple interfaces before being harnessed in an electrical circuit. Therefore, the total current, potential, and efficiency are dependent on losses incurred at each interface and could be vastly improved by optimizing individual electron transfer steps.

Many researchers are looking toward direct electron transfer (DET) between the active sites of PSI and electrodes to reduce these losses. Unfortunately, achieving DET is difficult due to the necessity of proper PSI orientation and the close proximity (<1 nm) of the active sites to the electrode material for electron tunneling. Alternatively, mediated electron transfer (MET) can be employed through the use of soluble redox mediators to shuttle charge between the active sites and electrodes. MET can benefit from the use of high surface area electrodes and increased loadings of PSI. Our group has studied both DET and MET within PSI bioelectrodes of various architectures. In this presentation, the incorporation of PSI into porous and translucent indium tin oxide (ITO) cathodes to achieve significant improvements in MET will be highlighted. Additionally, the limitations and challenges of DET, directions for improving MET in porous electrodes, and future prospects for improving charge transfer at PSI – electrode interfaces will be discussed.
In-Situ XAS and Eqcm Investigations of Redox Mechanisms in IrO2 Thin Film Electrodes
Authors: Hsieh Yi-Chieh , Tso Kuang-Chih , Wu Pu-Wei , Dunn Bruce S.
Published: May 2020

Bio-stimulating electrodes are recognized to be one of the most critical components for implantable biomedical electronic devices. In order to activate neurons for therapeutic functions, a desirable bio-stimulating electrode requires specific attributes including a large amount charge storage and high charge injection capacity along with a low impedance at the operating frequency of the device. Among the many electrode materials studied to date, iridium oxide has emerged as an especially promising candidate with superior characteristics for charge storage, biocompatibility and chemical inertness. In this presentation, we describe our studies on the interrelationships between charge transfer and structural changes in IrO2. In-situ X-ray absorption spectroscopy was used to determine the changes occurring in the oxidation states of IrO2 during cyclic voltammetry (CV) scans. These results are correlated with the structural changes occurring as determined by X-ray diffraction. In addition, we carried out eQCM measurements to better identify the electrochemical reactions associated with the redox peaks generated by the CV scans. The results of this study lead to a much better understanding of the operation of iridium oxide as a bio-stimulating electrode.
Electrochemical Characterization of Carboplatin Toward the Detection of Drug Resistance in Cancer
Authors: Luu Huy Tran Le , Nachtigal Mark , Kuss Sabine
Published: May 2020

Epithelial ovarian cancer (EOC) has the highest mortality rate among gynecological cancers and affects patients on all continents. Primary treatments involve surgery and the administration of chemotherapeutics, such as carboplatin, which is listed by the World Health Organization as an essential medication for the treatment of human cancers. Unfortunately, due to high rates of drug resistance of EOC towards carboplatin, cancer relapse rates are devastating, and the mechanisms of chemoresistance to carboplatin have not been adequately identified. Consequently, there is a dire need for innovative strategies that are able to detect carboplatin resistance in cancer and to further our understanding of the fundamental nature of chemoresistance towards carboplatin.

The presented work describes the thorough electrochemical characterization of carboplatin. We quantify the influx and efflux of carboplatin into/from ovarian cancer cells by electrochemistry to better understand mechanisms of carboplatin chemoresistance. Results emerging from this research will be important for future medical research developing novel agents to combat chemoresistance and will present the basis for future long-term funding applications under this collaboration.
Effect of Single Particle-Particle Interface on Photoelectrodes Performance
Authors: Hesari Mahdi , Sambur Justin , Mao Xianwen , Jung Won , Chen Peng
Published: May 2020

Light-to-energy conversion is an encouraging approach to overcome the energy crisis and generate clean fuels (e.g., hydrogen) and electricity. Photoelectrochemical cells (PECs) and photovoltaics (PVs) are two main technologies that have been used extensively for such conversion. PECs and PVs are consisting of a semiconducting electrode as light absorber materials. Traditionally, PECs and PVs are fabricated by accumulating a film of nanostructured semiconductors in which, the photogenerated charge carrier (e.g., electrons) has to pass through several nanostructures’ interfaces. We designed a sophisticated photoelectrochemical cell setup and used a focused laser beam (i.e., ~400 nm) to locally generate charge carriers at different location, i.e., before and after particle-particle interface. Our sub-particle, single-interface photocurrent measurements revealed that indeed there is a noticeable photocurrent drop per interface. Thus, such quantitative metric should be considered for surface and interface engineering of photoelectrode in PECs and PVs.
Stability Investigations of Platinum Electrodes in Nonaqueous Systems
Authors: Ranninger Johanna , Wachs Susanne J. , Möller Jonas , Mayrhofer Karl J. J. , Berkes Balázs B.
Published: May 2020

Fundamental understanding of electrode dissolution processes in nonaqueous media is crucial for applications like nonaqueous battery systems, sensors, capacitors but also organic electrochemistry and is inextricably related to economic considerations. The reasons for electrode degradation are among others anodic dissolution, cathodic dissolution or cathodic corrosion. Enhanced knowledge of dissolution mechanisms and factors like composition or structure of electrodes, electrolyte and temperature are important to optimize the operation conditions, limit electrode degradation and increase the lifetime of devices.

The development of the scanning flow cell (SFC) combined with an Inductively Coupled Mass Spectrometer (ICP-MS), allowing online stability studies, has given valuable insights into degradation mechanisms of different electrodes and catalyst materials in aqueous media which are relevant for applications like fuel cells and electrolyzers. We have developed an electrochemical flow cell (EFC) coupled to the ICP-MS which is suitable for the use in aggressive nonaqueous electrolytes. The flow cell is operated in an argon filled glovebox which allows us to conduct electrochemical experiments in completely inert atmosphere under the exclusion of oxygen and water.

Platinum is one of the most extensively studied electrode materials due to its excellent electrocatalytic activity and inertness in various applications. Our novel method allows new insights into the complex behavior of platinum in nonaqueous electrolytes, among others in its dissolution. New aspects regarding the stability of platinum in different nonaqueous electrolytes are unveiled depending on the chemical properties of the solvent and the conducting salt. While the dissolution behavior of completely water free protic electrolytes like methanol and aprotic electrolytes like acetonitrile is very similar, the dissolution behavior changes completely in presence of trace amounts of water. Furthermore, different cations and anions in the electrolyte effect the anodic dissolution and cathodic corrosion, respectively.

The controlled addition of water to nonaqueous electrolytes is an important tool to study the behavior of the formation and dissolution of the platinum oxide passivation layer and is not only relevant for nonaqueous electrocatalysis but also gives new insights into the dissolution mechanisms in aqueous electrolytes.

The details of the method and different platinum dissolution profiles in several nonaqueous electrolytes will be discussed. Additionally, dissolution mechanisms will be proposed based on studies with changing water content.
WITHDRAWN: Utilizing DNA Spacer to Design Differential Photoelectrochemical Biosensor
Authors: SAHA Sudip KUMAR , Victorious Amanda Pansy , Pandey Richa , Soleymani Leyla
Published: May 2020

This abstract has been withdrawn at the request of the authors.
Kappa-Carrageenan/Hierarchical Porous Activated Carbon Composite Film for Electrochemical Sensing of Dopamine
Authors: Hummel Matthew , Guo Ailin , Lu Shun , Gu Zhengrong
Published: May 2020

In this work, a novel electrochemical dopamine sensor was fabricated based on a composite film solely consisting of kappa-carrageenan and hierarchical porous carbon that was synthesized from alkali lignin directly. Following drop-casting onto a glassy carbon electrode and drying overnight, the film was characterized with scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray powder diffraction, and electrochemical tests. 5 ratios by mass of hierarchical porous activated carbon: kappa-carrageenan were studied for optimizing dopamine quantification. Utilizing differential pulse voltammetry for detection, the optimized system elicited a linear range of 1 - 600 μmol L-1 and an limit of detection (LOD) of 0.4 μmol L-1(signal to noise, S/N=3) The proposed system is easy to prepare and requires no synthetic binding agents. All materials and methods utilized were cost-efficient and readily available for commercial use. Due to the simple design of the sensor, it offers great potential for further modification and optimization.

Figure 1
Electrochemical Detection of Drug Efflux from Living Cells - Towards the Quantification of Drug Resistance in Bacteria and Cancer
Authors: Kuss Sabine , Luu Huy Tran Le , Islam MD Rafiqul
Published: May 2020

The rapid spread of drug resistance in bacteria as well as cancer has developed into a significant threat to the global public health. According to the World Health Organization (WHO), antibiotic resistance is present in every country, and various national and international health organizations, including the United Nations and the Infectious Diseases Society of America have called for the urgent development of new treatment and diagnostic strategies. The Centers for Disease Control and Prevention reports approximately 10 million deaths worldwide each year in connection with antibiotic resistance. Similarly, drug resistance in cancer is believed to be responsible for treatment failure in up to 90% of metastatic cancer patients. Cellular resistance mechanisms in both bacteria and cancer include cell membrane protein modifications, intracellular drug target alterations, and the over expression of efflux pumps. The latter are the result of an over-expression of efflux pump proteins, which enable cells to expel drugs rapidly from the cell interior, before these compounds can take effective action. Drug compounds and efflux pump proteins have recently caught the attention by the electrochemical community to develop new methodologies to understand and detect drug resistance in both bacteria and cancer by electrochemistry. Our research efforts focus specifically on drug compounds expelled from living biological cells by electrochemistry and their detection by standard electrochemical techniques, such as volatmmetry, as well as specialized instrumentation, such as scanning electrochemical microscopy (SECM). This presentation covers the characterization of common drug compounds, but also newly investigational antibiotic hybrids. Recent advances are presented towards the quantification of drug resistance in epithelial ovarian cancer (EOC), which has the highest mortality rate among gynecological cancers.
Nature Inspired Anti-Biofouling Strategy for the Detection of Protein Biomarkers Directly in a Drop of Blood
Authors: Adhikari Bal Ram , vallée-Bélisle Alexis
Published: May 2020

Electrode biofouling in complex biological fluids is one of the major problems in analytical electrochemistry. Direct electrochemical detection in human blood remains challenging due to quick surface passivation by proteins present in blood, degrading sensor’s sensitivity. This challenge has dramatically slowed down commercialization efforts of point-of-care devices. Here we have developed a simple nature-inspired electrochemical DNA hybridization (e-hyb) assay based on steric hindrance which enable electrodes to detect nanomolar concentration of proteins (i.e. antibody) directlywithin a drop ofblood without any sample preparation. This e-hyb assay involves two DNA strands; one-captured DNA immobilized on electrode surface and another complementary reporter DNA labelled with an electroactive molecule (methylene blue) at one end and a specific recognition element at the another end. In presence of a specific large analyte binding to the small recognition element, the reporter DNA cannot reach to the electrode surface due to steric hindrance. This simple strategy enables us to quantify different protein biomarkers (HIV antibody, anti-DNP antibody, anti-DIG antibodyetc) in human blood without being limited affected by biofouling.

Figure 1: e-DNA hybridization based anti-biofouling strategy for the detection of antibody in human blood

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In-Situ TEM Observation of Silver Nanodendritic Growth in Liquid
Authors: Hou Szu-Yu , Huang Chih-Yang , Chen Jui-Yuan , Wu Wen-Wei
Published: May 2020

Silver nanocrystals with highly branched morphologies are an appealing new series of nanomaterials owing to their unique structures, physicochemical properties, and exceptional potential as catalysts, optics, photography, microelectronics, bactericidal coatings, sensing materials, and building blocks for nanoscale devices. The properties related to their twin structure of the seed particles and the ratios between growth rates of different crystallographic facets of silver dendritic nanostructure. However, there is still a lack of information that how silver dendritic nanostructure growth by based particles aggregation and heterogeneous seed process remain unclear. Therefore, tracking particle growth by in-situ liquid cell transmission electron microscopy (LC-TEM) provides the direct evidence and extends the study of both dendritic nanostructure evolution and growth mechanisms. In this work, we observed the dynamic growth process of silver nanodendritic in solution by liquid cells with high resolution analysis. The following chemical equations describe the formation of Ag0 under electron beam radiation.

H2O → eaq
- + H•+ OH•+ H2O2 + H2 (1)

Ag2+ + 2 eaq
- → Ag (2)

Ag2+ + 2 H• → Ag (3)

The driving force comes from the non-uniformities in local electron does, the radiolysis of water could induce a concentration gradient among the species, which was a particularly significant factor to affect the particles attachment in non-equilibrium conditions resulted in inhomogeneous growth. The accumulation of Ag+ was reduced by electrons resulted in heterogeneous seeded growth of Ag0. The growth mechanisms of silver nanodendritic and aggregation behaviors are systematically studied from the dynamic and kinetic viewpoints, strengthening the knowledge in branched morphologies growth. Without a doubt, the field of synthesis and application of silver nanodendritic will keep moving forward as better understanding of their growth mechanisms are achieved.

Figure 1