bluuebunny/crossref_metadata_2025 huggingface dataset:
(Digital Presentation) Boosting Hydrogen Oxidation Reaction Activity of Nickel Based Catalyst By Reactive Spray Deposition Technology: Effects of Particle Size
Authors: Xing Jiale , Zeng Zhiqiao , Bliznakov Stoyan , Bonville Leonard J. , Maric Radenka
Published: July 2022

Ni-Based materials are one of the most promising candidates for hydrogen oxidation reaction (HOR) in anion exchange membrane fuel cells (AEMFC). However, the performance for pure Ni is limited. In this work, Ni mixed CeO2 nanoparticles supported on carbon black were synthesized for the first time by Reactive Spray Deposition Technology (RSDT) and followed by an oxygen reduction process in a furnace. By controlling the reaction parameters during the RSDT fabrication process, the particle size of Ni/CeO2/C is set at 3 nm. The resultant 3 nm catalyst Ni/CeO2/C catalyst exhibits excellent mass activity (14.92 mA mg-1
Ni) compared to the catalyst without the addition of CeO2 (which is Ni/C 4.39mA mg-1
Ni) as well as the activity of most of the other non-precious metal-based materials for HOR. The excellent electrocatalytic performance indicates that Ni/CeO2/C can be considered as a potential non-precious metal at the anodes for AMEFCs.
(Invited) Renewable Hydrogen Systems Enable Deep Energy Decarbonization of Power and Transportation Sectors
Authors: Haggi Hamed , Fenton James M. , Brooker Paul , Sun Wei
Published: July 2022

Climate change is one of the most preeminent challenges facing the world. Continued fossil fuel energy consumption at the current trajectory will result in a temperature rise of more than 3.5°C by the year 2050. Melting glaciers, rising sea levels, wildfires, floods, and extreme weather events such as heat waves and large storms, are likely to become more frequent or more intense. The Paris Agreement is a legally binding international treaty to reduce carbon emissions which led to keep the global temperature rise well below 2°C [1]. This target cannot be achieved without deeply decarbonized energy production which focuses on three main factors: 1) Reducing energy consumption through improved efficiency (optimize), 2) Shifting energy demand to electricity and away from combustion of fossil fuels (electrify everything), 3) Shifting entirely to zero-carbon technologies such as solar photovoltaic (PV), wind, hydrogen, etc. to generate electricity (decarbonize). According to the United States (U.S.) Environmental Protection Agency (EPA), the largest contributors to anthropogenic U.S. greenhouse gas emissions in the descending order are transportation (29%), electricity (25%), industry (23%), agriculture (10%), commercial (7%), and residential (6%) [2].

In our previous research, we focused on decarbonization pathways using utility solar, hydrogen consumption and production (electrolyzer, compressor, storage tank, and stationary fuel cells) for improved utilities operation without considering transportation sector demand [3]. Here the focus is on energy decarbonization for both power and hydrogen fueled transportation sector using hydrogen systems. To this end, a vertically integrated 33-node distribution network which is managed by distribution system operator (DSO) is optimized. The DSO manages all the assets in the network including natural gas power plants (combined cycle units and combustion turbine units), solar PV, distributed energy storage systems, hydrogen systems (including storage and refueling station) with the objective of cost minimization. Besides managing the aforementioned technologies, the DSO ensures safe and reliable operation of these assets by considering the technical and physical constraints of the network including voltage regulation, power flow and line congestion management, etc. The DSO in this study also manages the transportation sector hydrogen demand of fuel cell electric vehicles, medium- and heavy-duty vehicles.

Simulation results show that hydrogen demand from the transportation sector is the main driver in sizing of hydrogen system components. Additionally, for the 33-node distribution network to fully supply heavy-duty vehicles demand, natural gas power plants must be operated to supply the required electricity for the electrolyzers to supply hydrogen for these vehicles. Furthermore, different sensitivity analysis for various PV and hydrogen demand penetrations will be presented.
(Invited) Electrified Membranes for Transformation of Nitrate in Wastewaters
Authors: Winter Lea R , Elimelech Menachem
Published: July 2022

The release of nitrate to the environment from wastewater effluent and agricultural runoff contributes to groundwater contamination, harmful algal blooms, and disruption of biogeochemical nitrogen flows. Typical treatment methods are based on nitrate separation, which produces waste streams that are often discharged to the environment. Alternatively, nitrate conversion via electrochemical reduction eliminates the production of concentrated waste streams while avoiding the addition of reductant or hole scavenger chemicals to accomplish the reaction. However, major challenges for nitrate removal from water via electrochemical conversion involve reducing the use of expensive precious metal electrocatalysts while also improving the reaction activity and selectivity, catalyst stability, and mass transport of nitrate to electrocatalyst active sites. The use of electrochemical membranes as multifunctional porous flow-through electrodes could potentially address these challenges based on improved mass transport and altered kinetics under flow conditions within membrane pores.

Conductive membranes were fabricated using polymers combined with carbonaceous materials such as reduced graphene oxide (rGO) and carbon nanotubes. The rGO was functionalized with non-precious transition metal oxynitride electrocatalysts, where these catalysts showed higher nitrate conversion activity compared to the unsupported transition metal nitrides. The influence of catalyst materials, membrane fabrication process, and filtration conditions on nitrate reduction activity and selectivity were evaluated. In addition to the environmental impacts of closing the nitrogen loop by converting nitrate into innocuous N2, selective nitrate reduction to ammonia provides opportunities for recovery as fertilizer or carbon-free renewable energy storage. The prospects for reactive nitrogen recovery based on nitrate electrochemical conversion to ammonia were analyzed for various potential source waters.
(Digital Presentation) Role of Electronic Structure on Nitrate Reduction to Ammonium: A Periodic Journey
Authors: Carvalho Quinn , Marks Rylee , Stoerzinger Kelsey A
Published: July 2022

The perturbation of the nitrogen cycle via fertilizer amendment and fossil-fuel combustion has resulted in alarmingly increased nitrate concentrations in groundwater and coastal areas, with global human-health threatening consequences. Denitrification of drinking water, municipal cooling tower waste water, and industrial waste streams is a growing area of energy consumption, though still outpaced by the carbon-intensive Haber-Bosch production of ammonia from nitrogen for fertilizer production. Electrocatalytic nitrate reduction offers a competitive, distributable, and cyclic alternative to conventional fertilizer-production approaches, using electrons as a reducing agent without the need for added chemicals or elevated temperatures and pressures. However, nitrate reduction Faradaic efficiency to desired products (e.g. ammonium) is limited by two primary factors: (1) competition with the process of water reduction (i.e. reducing protons to form hydrogen gas); and (2) a complex reduction pathway where nitric oxide (NO) plays a critical role in determining selectivity.

Here we investigate nitrate reduction in neutral pH phosphate buffer over a series of 3d (Cu, Ni, Ni0.68Cu0.32, Co, Fe, Ti) and 4d
10 (Ag) transition metals (TMs), identifying properties of bulk resting electronic structure (e.g. work function [Φ] and d-band center energy [Ed
]) as descriptors for nitrate reduction Faradaic efficiency and selectivity to ammonium. We frame our discussion of these results within theoretical and empirical literature on hydrogen evolution and nitric oxide adsorption, finding Φ dictates total nitrate reduction Faradaic efficiency while Ed
determines selectivity towards ammonium. Nitrate reduction FE trends with work function, in-line with well-established trends between HER activity and work function. Selectivity towards ammonium increases as Ed
approaches and overcomes the Fermi level, increasing the adsorption energy of nitrate reduction intermediates (such as NO) by decreasing occupation of anti-bonding states.
Electrochemical Nitrate Reduction to Ammonia on Polycrystalline Copper Electrodes in Alkaline Solutions
Authors: Kim Yohan , Shim Minyoung , Byon Hye Ryung
Published: July 2022

Ammonia has widely utilized as the raw material of fertilizer and feeds in fuel cells and hydrogen storage materials (Orens. S, Proc. Natl. Acad. Sci. U.S.A.
2021,
118 (49)). In general, the Haber-Bosch process has supplied the mass production of ammonia (N2 + H2 → 2NH3). However, this chemical process requires high-temperature and high-pressure conditions to cleave the triple N2 and produces undesired CO2 gas, as CH4 is added for H2 generation. It is attractive to yield ammonia in milder conditions and more cost-effective methods. In addition, the usage of waste and eco-poisoned species, which is inevitably produced, is valuable as the reactant. For this purpose, nitrate (NO3
-) conversion using electrochemical methods has drawn attention. Nitrate has a high solubility in aqueous media and better reactivity than N2 gas at ambient temperature and atmospheric conditions. Nonetheless, the nitrate reduction undergoes multiple electron-transfer processes (NO3
- + 8e- + 9H+ → NH3 + 3H2O), causing low ammonia selectivity competing against byproducts such as hydrogen, nitrogen oxides, and hydroxylamine.

Here, I show critical factors determining the conversion selectivity of nitrate using Cu catalysts. I prepared three Cu foils treated by different surface cleaning processes. Surface morphology and roughness of Cu relying on the surface treatments significantly altered the conversion efficiency. In particular, nitric oxide (NO) was a pivotal intermediate to determine the final products, which was sensitive to the Cu surface condition. I will discuss details of the electrochemical nitrate reduction process observed by in-situ and ex-situ gas and spectroscopic analyses and correlate the conversion efficiency with the surface conditions of Cu foils.

Figure 1
(Digital Presentation) Electrochemical Recovery of Ammonium and Phosphate from Municipal Wastewater Sources: Kinetics and Water Chemistry
Authors: Greenlee Lauren F , Kekedy-Nagy Laszlo , English Leah , Anari Zahra , Abolhassani Mojtaba , Pollet Bruno Georges , Popp Jennie
Published: July 2022

Water contamination is ubiquitous and persists across our water resources and supply. Much attention is given to newly identified and emerging contaminants, but we also struggle to successfully mitigate “old”, or well-known, contaminants, which have included ammonia, nitrate, and, more recently, phosphate in municipal wastewaters. However, these compounds are also critical nutrients used to support the global industrialized agriculture sector. Phosphate is of particular importance and concern because phosphate-based fertilizers are currently produced through the mining of phosphate rock, a limited resource mineral. The world’s known available supply of phosphate rock is predicted to become limited within the range of 30 – 200 years, and the flow of phosphorus through the agricultural food cycle is unidirectional, with large portions of mined phosphorus ending up in the environment and landfill. Ammonia is produced for fertilizer and other chemical uses via the Haber-Bosch process, which, annually, uses 2% of global fossil fuel energy demand and contributes 450 M metric tons of CO2 to global emissions. Meanwhile, the technical treatment train for municipal wastewater treatment facilities targets removal of ammonia and phosphate as contaminants, enabling this one-way flow of nutrients from mineral sources and energy-intensive processes through food to waste. This scenario is no longer tenable as we face limited phosphorus world-wide, as well as energy and food security challenges.

In our research, we focus on a magnesium anode-based electrochemical system for the precipitation and recovery of ammonium and phosphate nutrients from municipal wastewater sources. In this study, we have evaluated four different natural wastewater sources, three municipal and one industrial meat processing source to understand how differences in wastewater source water composition affect phosphate and ammonium recovery, and inversely, how the electrochemical treatment process affects resulting wastewater chemistry post-treatment. In this talk, I will discuss our recent results that have shown that phosphate removal kinetics are affected by key water chemistry parameters of chloride concentration, ammonium concentration, calcium concentration, and total organic carbon. Phosphate removal through precipitation showed a two-stage kinetic behavior, with a fast kinetic regime prior to 1 min, and a zeroth order rate from 1 min to 30 min. Corrosion rates of the magnesium anode varied over an order of magnitude and are correlated with the differences in water chemistry. Experimental Mg consumption during the electrochemical process is greater than theoretical Mg consumption resulting in an underestimate of costs, highlighting the importance of experimentally-measured Mg consumption as the more appropriate measure of treatment cost.
(Digital Presentation) A Constant Deformation Modulus for the Simulation of Gas Diffusion Layer
Authors: Qitong Shi , Wang Qianqian , Cong Feng , Ming Pingwen
Published: July 2022

The deformation of gas diffusion layer(GDL) directly affects gas diffusion and electron transfer in the fuel cell. The modulus of stress-strain relationship is the basic parameter in the process of deformation. In this paper, based on beam bending theory and geometric probability analysis, a nonlinear analytic model of stress-strain with physical meaning is established, and a constant deformation modulus of GDL is given. Based on the deformation modulus, we further simulate the inhomogeneous deformation of GDL within a half channel-rib model. The results indicate that the uneven deformation with deformation modulus is more significant than that with linear elastic modulus in the same condition. Finally, a shape-dependent bending radius design for the rib edge is proposed, in which the inhomogeneous deformation of GDL becomes smoother as the radius increases, thereby improving the service condition of GDL and prolonging its service life.
Pd–Ag Bimetallic Catalysts with Core–Shell Engineering for Efficient Hydrogen Production from Formic Acid Decomposition
Authors: Goo Bon Seung , Han Sang Woo
Published: July 2022

Fine control of the ligand and strain effects of secondary elements on the catalytic function of primary elements is critical for developing high-performance bimetallic catalysts. In this paper, we describe a method for making Pd–Ag bimetallic core–shell nanocatalysts with synergistic ligand and Ag strain effects. (PdAg alloy core)@(ultrathin Pd shell) nanocrystals with regulated core compositions and shell thicknesses, as well as a well-defined octahedral shape, could be achieved through precision core–shell engineering. The produced octahedral PdAg@Pd core–shell nanocrystals showed excellent catalytic activity in the creation of hydrogen from the breakdown of formic acid. The highest catalytic activity was attained using PdAg@Pd nanocrystals made up of PdAg alloy cores with an average Pd/Ag atomic ratio of 3.5:1 and a 1.1 atomic layer of Pd shells, which set a new record for catalytic activity.
One-Pot Production of Pt–Ni Alloy Nanodendrites on Ceria Nanosheet Supporting Materials with High Electrocatalytic Performance Toward Methanol Oxidation and Oxygen Reduction
Authors: Kwon Yongmin , Lee Eun Jin , Han Sang Woo
Published: July 2022

To create better fuel cell catalysts, effective approaches to generate hybrid materials comprised of intimately connected metal nanocatalysts and nonstoichiometric metal oxides with finely regulated topologies are very desirable. The production of closely connected metal (PtNi alloy)–metal oxide (CeOx, ceria) hybrid nanostructures is reported here using a simple one-pot synthesis technique. Heating a mixed metal (Pt, Ni, and Ce) precursor solution in oleylamine/oleic acid resulted in well-defined PtNi/ceria hybrids, in which PtNi alloy nanodendrites with multiple branches are evenly spread over small-grained ceria nanosheets. The ceria nanosheets in the hybrids have a large number of oxygen vacancies and a high conductivity due to their small grain size. In comparison to carbon-supported counterparts and a commercial catalyst, the prepared PtNi/ceria hybrids exhibited outstanding electrocatalytic activity and stability for both methanol oxidation and oxygen reduction reactions, which can be attributed to the synergistic effects of the Ni component and ceria on the enhancement of the electrocatalytic function. The current technique will be used to create the best multicomponent catalysts for specific processes.
Investigating the Application of Graphitic Carbon Nitrides as Additives in Proton Exchange Membranes for Fuel Cells
Authors: Smith Keenan , Miller Thomas Samuel , Brett Dan , Foglia Fabrizia
Published: July 2022

Proton exchange membranes (PEMs) that conduct protons between electrodes, whilst minimizing the transport of reactant molecules are vital components of energy storage and conversion devices, such as fuel cells (FC), electrolysers and redox flow batteries. Despite over half a century of synthetic development, perfluorosulfonic acid membranes, such as Nafion, remain the industry standard. Performance improvements have thus relied on use of additives to improve water retention and proton conductivity. However, understanding the way in which these additives arrange favourably into the phase separated morphology of the polymer structure and positively influence water uptake and proton conductivity has eluded researchers.

Polytriazine imide structured graphitic carbon nitride (PTI) with a graphitic structure of repeating C12N12H3 structural voids is an ideal candidate additive due to its specific size, functional groups, and hydrophilicity.[1] Using neutron scattering we directly revealed the importance of triazine and bridging N-H groups for facilitated water transport through the intralayer voids and speculate their importance in hydrated proton transport.[2]

Herein, ultrasonic spray printing (USP) was used to incorporate PTI nanosheets into the phase separated morphology of Nafion. Fabrication was optimised via PTI wt.% loading and USP fabrication parameters to obtain a high-performance PEM with proton conductivity higher than commercial Nafion at low and high hydration. USP allowed an increased proportion of PTI to be added over conventional solution casting method without deleterious effect of restacking and agglomeration. Neutron reflectivity (NR) and quasi-elastic neutron scattering were used to probe the structure and dynamics of polymer framework, water and ions. Comparison with pure Nafion and other composite materials provided insight into the way in which graphitic additives arrange inside the polymer aggregates and enhance water transport. This work highlights PTI as an effective 2D material for structural tuning of phase separated polymers for contiguous proton and water transport within the semi-crystalline framework, as well as highlighting an experimental approach to reveal nanoscale structure-property relationships.

[1] T. M. Suter, T. S. Miller, J. K. Cockcroft, A. E. Aliev, M. C. Wilding, A. Sella, F. Corà, C. A. Howard, P. F. McMillan, Chem. Sci., 2019, 10, 2519-2528

[2] F. Foglia, A. J. Clancy, J. Berry-Gair, K. Lisowska, M. C. Wilding, T. M. Suter, T. S. Miller, K. Smith, F. Demmel, M. Appel, V. G. Sakai, C. A. Howard, M. Tyagi, F. Coràand, and P. F. McMillan, Sci. Adv., 2020, 6, eabb6011
Degradation Effect of Gas Diffusion Layer on Water Transport in Polymer Electrolyte Membrane Fuel Cell
Authors: Jung Sung Yong , Park Jooyoung , Park Hanwook , Oh Hwanyeong , Moon Jong Woon
Published: July 2022

Hydrogen is converted to electric power by proton exchange membrane fuel cells (PEMFCs), which have received significant attention for transportation applications because of their high energy efficiency. In order to ensure the long-term stability, understanding about their long-term durability is essential because the operating performance deteriorates over time. Gas diffusion layers (GDLs) manage the transport of water generated from the CL during chemical reactions, and the degradation of the GDL significantly deteriorate the fuel cell performance. Compared to the fresh GDL, the water transport characteristics of GDL aged by inserting hydrogen peroxide solutions are investigated. The dynamic movement of the water meniscus inside the GDL is visualized using synchrotron X-ray imaging. Unlike the pristine GDL having snap-off patterns, water continuously transports through the degraded GDL representing the piston-like movement, and pressure fluctuations are not observed. This difference shows the change of the dominant local transport mechanisms due to GDL degradation. The temporal pressure variations are simultaneously measured, and the pressure and time at breakthrough (BT) are compared. The aged GDL exhibits a larger BT pressure and requires a longer time to achieve the first BT. Longer BT time in the degraded GDL can reflect a higher water saturation level. GDL degradation leads to the loss of polytetrafluoroethylene (PTFE) which is commonly treated to ensure efficient mass transport by restraining water clogging in the GDL pores due to the increase of hydrophobicity. Despite the reduction in hydrophobicity, The PTFE loss can increase BT pressure by reducing the pore size and the actual path length of the water flow. The increase in the BT time and BT pressure, as well as continuous transport, can disrupt fuel supply to chemical reaction sites, thereby deteriorating the PEMFC performance. This study provides a comprehensive understanding of the effect of GDL degradation on mass transport in PEMFCs.

Figure 1
(Digital Presentation) Assessing the Energy Intensity of Product Purification in CO2 Electrolysis
Authors: Edwards Jonathan P. , Alerte Théo , Gabardo Christine M. , O'Brien Colin P. , Gaona Adriana , Wicks Joshua , Obradović Ana , Sarkar Amitava , Jaffer Shaffiq A. , MacLean Heather L. , Sinton David , Sargent Edward H.
Published: July 2022

The electrochemical reduction of carbon dioxide (CO2RR) to chemical feedstocks, such as ethylene (C2H4), is an attractive means to mitigate emissions and store intermittent renewable electricity. Much research has focused on improving CO2 electrolysis cell efficiency; less attention has been paid to the downstream purification of outlet product streams. In this presentation, we model the use of mature downstream separation technologies as part of the overall production of polymer-grade C2H4 from CO2. We find that CO2 removal is the most energy-intensive downstream separation step. We identify opportunities to reduce separation energies ten-fold to ∼22 GJ/tonne C2H4 through necessary improvements in C2H4 selectivity (>57%), cathodic CO2 conversion (>80%), and CO2 crossover (0 mol CO2/mol e−). This work highlights the influence of cell performance parameters on downstream separation costs and motivates the development of new, efficient separation processes better suited to the distinctive outlet streams of CO2 electrolyzers.
(Digital Presentation) Electrochemical Characterization of Microbial Fuel Cell Electrodes Using Cyclic Voltammetry and Electrochemical Impedance Spectroscopy
Authors: Quintero Carlos , Kesh Pooja , Shastri Padmaja , Martic Sanela
Published: July 2022

Renewable energy sources are required to lessen energy generation's reliance on fossil fuels. Microbial fuel cells (MFC) exploit microbial metabolic processes to oxidize organic matter to generate energy from wastewater; they serve as a low-cost, sustainable form of wastewater management. Despite the development of effective MFCs, low efficiency and power density have prevented their widespread adoption over traditional fuel cells. Modification of MFC electrodes has been investigated as a means to improve their limited power output. Here we assessed the MFC carbon cloth electrodes and compared them to a traditional glassy carbon, and clean carbon cloth. The electrochemical properties of the electrode surfaces were explored using a three electrode cell consisting of a platinum wire counter electrode and Ag/ AgCl/ 1M KCl reference electrode. Electrolyte dependent studies were conducted in phosphate buffered saline (PBS) in the presence of ferri/ferrocyanide. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and square wave voltammetry (SWV) of the solution redox couple with various working electrode were performed in order to characterize electrode surface, prior, and post MFC use. The ultimate goal is to optimize the electrode surface chemistry to promote optimal MFC performance.
(Digital Presentation) Improved Densification of Proton Conducting BaCe0.5Zr0.3Y0.2O3-δ by Impurity Addition
Authors: Fung Kuan-Zong , Tsai Yuan Jie , Tsai Shu-Yi
Published: July 2022

BaCe0.5Zr0.3Y0.2O3-δ (BCZY) electrolyte is known to be a high proton conducting electrolyte for proton-solid oxide electrolyzer cell (P-SOEC) applications. There are some advantages such as (1) Reduce Cr evaporation and mitigate materials degradation, (2)Use of lower cost metals, alloys and coatings, (3) Ease of gas sealing, (4) Reduced cost of hydrogen production by using proton conducting electrolyte. To become a desired solid electrolyte with >95% relative density, a typical BCZY electrolyte needs to be sintered at temperatures greater than 1400°C. A better sintering approach was developed in this study.

With slight modification on sintering conditions, dense BaCe0.5Zr0.3Y0.2O3-δ electrolyte was obtained at a temperature as low as 1200°C. Without any modification, BCZY reached 90% relative density only when sintered at 1250°C. With proper impurity addition, BCZY may reach 97% relative density under the same conditions. From analysis, it is suggested that the densification of BCZY is promoted due to impurity induced liquid-phase sintering mechanism. In addition, the conductivity of highly densified BCZY reached 5.86×10-3 S/cm at 700°C. The crystal structure and microstructure of sintered BCZY was also characterized using XRD and field-emission SEM.
Organic Electrochemistry and the Use of Microelectrode Arrays to Probe Small-Molecule Protein Interactions
Authors: Moeller Kevin D , White-Drayton Kendra , Liu Siyue , Chang Yu-Chia
Published: July 2022

While electrochemical methods offer many unique opportunities for synthesis,1 the relationship does work in both directions. As part of an effort to develop microelectrode arrays as tools for monitoring small molecule – receptor interactions in real time, but have been working to show how synthetic chemistry can be used in order to build two-dimensional addressable surfaces on an array. The reactions themselves work nicely. But the overall strategy that has as its focus the construction of addressable molecular libraries that can be used to guide synthetic efforts brings with it not only synthetic challenges, but analytical ones as well. Many of the common direct detection methods used on microelectrode arrays and other electrochemical sensors are not compatible with a polymer coated electrode surface that has a lifetime consistent with using electrochemistry interactively with a synthetic endeavor. The surfaces required are thicker and more robust than typical SAMs that need to survive for months and be stable to a myriad of synthetic efforts.

The result is a need to develop indirect methods for detecting binding events on the arrays. These methods are modeled after electrochemical impedance experiments and take advantage of redox mediators in the solution above the array. A current is established for the mediator at each electrode in the array and then that current used to monitor binding events between molecules on the surface of the electrodes and biological targets in solution. In the talk to be presented, a quick review of how the surface used, how those surfaces can be functionalized, and how molecules on an array can be characterized will be presented along with a guide for how to conduct the analytical experiments used, how those methods can be calibrated, the problems that can arise, and how those problems can be recognized and addressed.

References:

Graaf, M. D.; Moeller, K. D. Langmuir, 2015, 31, 7697-7706.

Graaf, M. D.; Marquez, B. V.; Yeh, N. H.; Lapi, S. E.; Moeller, K. D. ACS Chem. Bio.
2016, 11, 2829-2837.

Yeh, N. H.; Zhu, Y.; Moeller, K. D. ChemElectroChem
2019, 6, 4134-4143.

Krueger, R.; Moeller, K. D. J. Org. Chem.
2021, 86, 15487-15865.
Electrochemical Monitoring of the Superoxide Anion Radical with Quercetin and Metallo-Quercetin Complexes
Authors: Lewis Tyra , Martic Sanela
Published: July 2022

Excess production of reactive oxygen species (ROS), such as the superoxide anion radical (O2˙–) can contribute to oxidative stress, and subsequently the onset of some pathological diseases. The free radical, O2˙–, is naturally generated in the body via a single electron reduction of molecular oxygen.1-3 Phenolic compounds such as flavonoids have strong antioxidant properties against ROS, including O2˙–.1,3 Due to their ability to donate an electron to the ROS, antioxidants actively act as free radical scavengers, which allows for prevention of cell damage and related health issues induced by ROS production.1 In addition to antioxidant properties, flavonoids such as quercetin (QCR) also play a role as metal ion chelators, by which their coordination with biologically relevant metal ions results in the formation of metallo-flavonoid complexes.2 Metal ions are known to regulate ROS activity via Fenton reactions, which may also influence the antioxidant activity and capacity of the flavonoid upon complexation. The role of metal ions and metallo-flavonoid complexes as antioxidants towards O2˙– is not fully understood. Herein, cyclic voltammetry (CV) was employed for electrochemical generation of the O2˙–/O2 redox couple.4 The anodic and cathodic peaks associated with the redox couple were monitored prior and post interaction with QCR and its metallo-QCR complexes. Overall, CV data show a decrease in anodic and cathodic peak currents, demonstrating varying extents of antioxidant activity and O2 reactivity with the antioxidants.

References

[1] N. L. Zabik, S. Anwar, I Ziu, S. Martic-Milne, Electrochim. Acta,
296, 174-180 (2019).

[2] M. M. Kasprzak, A. Erxleben, J. Ochocki, RSC Adv.,
5, 45853-45877 (2015).

[3] S. Ahmed, F. Shakeel, Czech J. Food Sci.,
30, 153-163 (2012).

[4] T. Lewis, W. Wallace, F. Dingman Peterson, S. Rafferty, S. Martic, Electrochem. Sci. Adv., e2100054 (2021).
(Digital Presentation) Selective Electrochemical Fluorination of Dithioacetals and O,S-Acetals Bearing α-Electron-Withdrawing Groups
Authors: Fuchigami Toshio , Yin Bin , Inagi Shinsuke
Published: July 2022

Organic electrosynthesis is expected to be a typical green chemical process.1 On the other hand, organofluorine compounds are key materials applied in daily life because of their versatile utility as functional materials, pharmaceuticals, and agrochemicals. Although organic electrosynthesis has a long history2, electrosynthesis of organofluorine compounds has been unexplored until ca. 30 years ago. With these facts in mind, we have developed electrochemical systems for selective fluorination of organic compounds including macromolecules and molecular conversion of organofluorine compound.3-7

In this talk, we will describe selective anodic fluorination and fluoro-desulfurization of dithioacetals and O,S-acetals having α-electron-withdrawing groups using various poly(HF) salts and solvents. It was found that oxidative elimination of α-proton followed by fluorination and fluorodesulfurization were greatly affected by EWG and/or electrolytic conditions.8,9

References

1) Fuchigami, M. Atobe, S. Inagi, Fundamentals and Applications of Organic Electrochemistry:
Synthesis, Materials, Devices, Wiley, 2014.

2) Fuchigami, Chem. Rec.,
21
, 2079 (2021).

3) Fuchigami, S. Inagi, Acc. Chem. Res.,
53
, 322 (2020).

4) Inagi, T. Fuchigami, Chem. Commun. (Feature Article),
47
, 10211 (2011).

5) Oyanagi, H. Ishii, S. Inagi, T. Fuchigami, J. Electrochem. Soc.
167 155511 (2020).

6) Ito, K. Kondo, H. Ishii, S. Inagi, T. Fuchigami, J. Electrochem. Soc., 168, 065502 (2021).

7) Shida, T. Fuchigami, S. Inagi et al., J. Org. Chem., 86, 16128 (2021).

8) Yin, S. Inagi, T. Fuchigami, Beilstein J. Org. Chem.
,

11

, 85 (2015).

9) Yin, S. Inagi, T. Fuchigami, Electrochem. Sci. Adv., in press.
(Digital Presentation) Electrochemical Dehydrogenative C–P Bond Formation for the Synthesis of Phosphacycles Using DABCO As a Mediator
Authors: Mitsudo Koichi , Kurimoto Yuji , Yamashita Jun , Suga Seiji
Published: July 2022

Phosphole oxide-containing π-conjugated molecules have been attracting attention due to their electron acceptability and thermal and chemical stability, and have been used as an important motif for organic functional materials. Among them, diarylphosphole oxide (DPO) is a key motif in the design of phosphole-containing organic functional materials. Recently, intramolecular cyclization of biarylphosphine oxides (BPOs) has received attention as a straightforward way leading to DPOs. BPOs are readily available and easy to handle starting substrates. Although several efficient methods have been reported for synthesizing DPOs with this protocol, these methods require transition metal catalysts, strong acids or excess amounts of acid. Therefore, the development of a transition metal-free and environmentally benign synthetic methodology for synthesizing DPOs is highly desirable.

To overcome the situation, we developed the first electrochemical synthesis of DPOs from BPOs via a dehydrogenative C–P bond formation. The protocol does not use a transition metal mediator and instead uses readily available and inexpensive DABCO as an organic hydrogen atom transfer (HAT) mediator. In the presence of DABCO, the desired C–P bond formation proceeded smoothly and a wide variety of DPOs could be obtained. This method can also be applied to the synthesis of six-membered phosphacycles. Several control experiments were carried out, and the results suggest that a phosphinyl radical was generated in situ and the reaction would proceed via a radical pathway.

Figure 1
(Digital Presentation) Scalable Synthesis of Versatile Intermediate for Azanucleoside Derivatives Via directanodic N-α Hydroxylation
Authors: Kurose Yuma , Okamoto Kazuhiro , Okada Yohei , Kitano Yoshikazu , Chiba Kazuhiro
Published: July 2022

Azanucleosides are found to show unique pharmacological activities even without incorporating into oligonucleotides and are used as anticancer and antivirus agents. Practical synthesis routes of azanucleosides are of exceptional importance to enhance the development of (oligo)nucleotide therapeutics. Previously, we reported the synthetic methods of azanucleosides by using electrochemical approaches, which has now been offering green and sustainable redox options in the field of synthetic organic chemistry. However, scaling-up of the reactions remains challenging since continuous production is essentially not possible. Herein, we report the direct anodic N-α hydroxylation of prolinol derivatives as useful intermediates for azanucleosides. Cyclic voltammetry study clearly reveals that the presence of water facilitates the oxidative electron transfer events. The reaction is applicable for large scale production and thus could enhance the development of (oligo)azanucleotide therapeutics.
(Digital Presentation) Synthesis of Ureas and Carbamates from Carbon Tetrahalides By B12-TiO2 Catalyst Modified with Magnesium Ion
Authors: Tanaka Miho , Shichijo Keita , Shimakoshi Hisashi
Published: July 2022

Organometallic B12 compounds are unique metal complexes having a cobalt-carbon s-bond present in biological systems. Cleavage of the metal-organic σ-bond initiates many B12 dependent enzymatic reactions. Based on unique properties of B12 enzymes, many B12-inspired reactions were developed.1-3 Here we report the visible light-driven B12inspired reaction for the synthesis of base chemicals from carbon tetrahalides as C1 building block. The hybrid catalyst, B12-Mg2+-TiO2, composed of the B12 derivative and titanium oxide modified with magnesium ion (Mg2+-TiO2) was synthesized for the visible light-driven catalytic reaction (Figure 1). Carbon tetrachloride (CCl4) was converted to N,N-diethylurea by the B12-Mg2+-TiO2 catalyst under the visible light irradiation (l>420 nm) with diethylamine (Et2NH) in air at room temperature. Valuable ureas are synthesized from CCl4 under mild condition. This photochemical catalytic reaction was applied to the synthesis of asymmetric ureas, carbamates, and carbonate ester via carbamoyl chloride in the presence of corresponding nucleophiles, RNH2, R2NH, ROH. Furthermore, the reactions were applied to carbon tetrabromide (CBr4) as substrate. Carbon tetrabromide is a commercially available solid compound which is stable at room temperature and can be easily handled. Scope of substrate and detailed reaction mechanism will be reported in this presentation.

References

[1] H. Shimakoshi, Y. Hisaeda, Chem. Rec., 2021, 21, 2080.

[2] Z. Luo, H. Shimakoshi et al, J. Org. Chem., 2021, 86, 5983.

[3] K. Shichijo, M. Fujitsuka, Y. Hisaeda, H. Shimakoshi, J. Organomet. Chem., 2020, 907, 121058.

Figure 1
Electrochemical Detection of Carboplatin-Resistance in Ovarian Cancer
Authors: Luu Huy Tran Le , Nachtigal Mark W. , Kuss Sabine
Published: July 2022

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. The uptake of carboplatin by ovarian cancer cells was quantified by electrochemistry to better understand mechanisms of carboplatin chemoresistance. Scanning Electrochemical Microscopy studies demonstrate a differential behavior between drug-susceptible and drug-resistant ovarian cancer cells, in response to carboplatin exposure. Results emerging from this research might be important for future medical research, developing diagnostic and treatment strategies to combat chemoresistance.
Intact Photosynthetic Bacteria-Based Electrochemical Biosensors
Authors: Grattieri Matteo , Gubitosa Jennifer , Rizzi Vito , Buscemi Gabriella , Stufano Paolo , Agostiano Angela , Trotta Massimo , Cosma Pinalysa , Farinola Gianluca M
Published: July 2022

Utilizing photosynthetic entities in electrochemical systems enables converting solar energy into electrical energy, obtaining bio-hybrid photo-electrochemical systems. Such systems have been recently proposed for micro power generation, bioelectrosynthesis, and biosensing for in-situ water quality monitoring.[1] However, due to the photosynthetic apparatus in bacteria (i.e., purple bacteria and cyanobacteria) being physically separated from the electrode surface by the presence of various membrane layers, artificial approaches to divert the photoexcited electrons are required. As a result, research efforts have been focused on developing bio-compatible approaches to facilitate the transfer of photoexcited electrons from these bacteria to the electrodes (and vice versa).[2] Herein, a sustainable biophotoanode based on intact purple bacteria is utilized for the monitoring of phenol-class contaminants that affects photocurrent generation. Specifically, we focused on nitro-phenols and other phenols that might be released in water when food/agricultural wastes are disposed into the environment. All the investigated compounds are known to be toxic, affecting both humans and animals’ health. Furthermore, to follow the green chemistry and bio-circular economy principles, approaches for the possible removal/recovery of these phenols and their degradation products were also investigated, with their possible re-use as active compounds in biomedical applications.[3] Challenges and future research directions for the application of these systems in the field will be discussed.

References:

[1] M. Grattieri, Purple bacteria photo-bioelectrochemistry: enthralling challenges and opportunities, Photochem. Photobiol. Sci., 19 (2020) 424-435.

[2] M. Grattieri, K. Beaver, E.M. Gaffney, F. Dong, S.D. Minteer, Advancing the fundamental understanding and practical applications of photo-bioelectrocatalysis, Chem. Commun., 56 (2020) 8553-8568.

[3] J. Gubitosa, V. Rizzi, A. Lopedota, P. Fini, A. Laurenzana, G. Fibbi, F. Fanelli, A. Petrella, Laquintana, N. Denora, R. Comparelli, P. Cosma, One pot environmental friendly synthesis of Gold Nanoparticles using Punica Granatum Juice: a novel antioxidant agent for future dermatological and cosmetic applications, J. Colloid Interface Sci. 521 (2018) 50–61.
Fast and Efficient Voltammetric Detection of L-Tryptophan in Dietary Supplements Using Carbon Electrodes Modified with Poly(L-Arginine)
Authors: Lima Dhésmon , Pessoa Christiana , Wohnrath Karen , Marcolino Junior Luiz Humberto , Bergamini Marcio Fernando
Published: July 2022

Tryptophan (TRYP) is an essential amino acid that plays several key roles in different physiological processes, ranging from acting as a building block for protein synthesis to being involved in neurotransmission and cellular signaling.1 Humans can only obtain TRYP from food intake,1 and therefore this compound is frequently added to dietary supplements. Considering the potential toxic effects that arise from TRYP overdoses,2 an efficient quality control should be performed on products containing TRYP in their formulations. In this way, this work proposes an efficient voltammetric sensor as a cost-effective and feasible tool to detect TRYP in commercial supplements. The sensor was based on glassy carbon electrodes modified with poly(L-arginine) (GCE/p-ARG), which was electrochemically synthesized in situ from L-arginine monomers.3 The conditions for p-ARG electropolymerization were optimized through multivariate statistical approaches in order to enhance the electrode’s sensing capability. Cyclic voltammetry and electrochemical impedance spectroscopy analysis in the presence of [Fe(CN)6]3-/4- redox probe showed that p-ARG significantly improved the electron transfer at the electrode surface. TRYP was irreversibly oxidized on GCE/p-ARG displaying a peak at +0.73 V (vs. Ag/AgCl), which was more intense than the anodic peak showed by the bare GCE. This was due to the presence of p-ARG on the GCE surface, which enabled the occurrence of multiple interactions that favoured TRYP detection. The amino acid oxidation followed a diffusion-controlled mechanism and showed to be dependent on the supporting electrolyte pH. A linear relationship between the anodic peak current (obtained through square wave voltammetry) and the TRYP concentration was observed in the range from 1.0 to 7.0 μmol L-1. Limits of detection and quantification were found to be equal to 0.30 and 0.91 μmol L-1, respectively. The developed electroanalytical method was successfully applied to detect TRYP in dietary supplements, with good precision and accuracy. In conclusion, it can be stated that the GCE/p-ARG is a promising candidate for food and pharmaceutical industry to enable cheap, fast, and reliable quality control of TRYP-based commercial products.

References

M. Platten, E. A. A. Nollen, U. F. Röhrig, F. Fallarino, and C. A. Opitz, Nature Reviews Drug Discovery, 18, 379–401 (2019).

Y. Xia, F. Zhao, and B. Zeng, Talanta, 206 (2020).

J. Soleymani et al., Materials Science and Engineering C, 77, 790–802 (2017).
Electrochemical Bioremediation of Uranium VI Using Geobacter Sulfurreducens on Boron-Doped Diamond Electrode Surface
Authors: Acevedo Alexis J. , Cabrera Carlos R. , Toranzos Gary
Published: July 2022

The development of nuclear science and technology has led to increasing nuclear waste containing uranium. The contamination associated with nuclear activity, especially uranium, is a significant concern for human and environmental health. Due to the high toxicity, radioactivity, and extensive half-life of uranium, it is necessary to find a way to remove it from the environment. One alternative to solve this problem is bioremediation. With this technique, microorganisms can be used to reduce, eliminate, contain, or transform hazardous waste like radionuclides. This research proposes using the bacteria Geobacter sulfurreducens to reduce uranium (VI) (U(VI)) to uranium (IV) (U(IV)). The experiment consists in the G. sulfurreducens' immobilization using the boron-doped diamond electrodes (BDD) as an electron donor by electrochemical processes. Taking advantage of the bacteria's microbial metabolism process and using U (VI) as an electron acceptor will reduce the ion to U (IV). First, a potential of -500mV (vs. Ag/AgCl) will be applied to immobilize the G. sulfurreducens’ to the BDD electrode surface. Second, with the application of a potential between -500mV to -700mV (vs. Ag/AgCl), it will expect to reduce the uranium ion and remove it from the media. Preliminary studies of the behavior of BDD electrodes in the presence of U(VI) had been carried out to determine the electrochemical conditions at which the substrate works with this ion. The results found with these studies will show how G. sulfurreducens’ will improve U(VI) bioremediation through electrochemical processes.

This research has the financial support from the DOE- Minority Serving Institutions Partnership Program, National Nuclear Security Administration, "Scholarly Partnership in Nuclear Security (SPINS)", Grant Number DE NA0003980.

Figure 1