bluuebunny/crossref_metadata_2025 huggingface dataset:
Purification of Copper-Contaminated Vanadium Electrolytes Using Vanadium Redox Flow Batteries
Authors: Reynard Danick , Vrubel Heron , Dennison Christopher R , Battistel Alberto , Girault Hubert H.
Published: May 2020

Corrosion of carbon-based electrodes and bipolar plates is a major challenge and a common cause of failure in commercial vanadium redox flow batteries (VRFB). Herein, we describe a typical carbon corrosion that occurred on several stacks of a 10kW/40kWh and a 200kW/400kWh commercial vanadium redox flow batteries (VRFB) installed in the framework of a demonstrator. Cracks through graphite bipolar plates enabled the electrolyte to leach the copper current collectors and contaminated the entire electrolyte solution with copper.

In this work, we first highlighted the deleterious effects of copper contaminants on the operation of a VRFB. It was observed that metallic copper enhanced the parasitic hydrogen evolution reaction (HER) on the negative side and accelerated the oxidation state imbalance between the two redox electrolytes. To tackle the problems related to copper pollution, a simple, eco-friendly and cost-effective procedure to identify copper contamination on-site and to purify the electrolyte was developed.

A classical VRFB stack was used to plate out the copper ions contaminants. The optimal cathode potential for copper deposition onto carbon felt electrode was determined to be −100 mV vs. SHE. The process described was successfully used to purify on-site 6000 L of vanadium electrolyte (V+3/V+4 mixture) to levels below 1 ppm. At the end of the purification, the stack was regenerated by flashing 20-30 L of electrolyte that represents only a fraction of what would have been necessary to dispose the contaminated electrolyte. This work has been accepted as a full paper in ChemSusChem. [1]

[1] D. Reynard, H. Vrubel, C. R. Dennison, A. Battistel, H. Girault, ChemSusChem
2019, 12, 1222.

Figure 2 A. Schematic illustration of the purification process developed to remove copper contaminants from the vanadium electrolytes B. SEM images of fresh carbon felt (a), carbon felt sample close to the inlet (b) and the outlet of the single-cell (c), and carbon felt sample after re-generation (d) C. Evolution of copper concentration (ICP-MS) at the negative-side outlet and the container electrolyte with time of purification

Figure 1
Electro-Thermal Modeling of Fe/V Flow Battery
Authors: Magallanes Laura , Rowe Andrew
Published: May 2020

Reliable, low cost energy storage solutions are needed to manage variability, provide reliability and reduce grid-infrastructure costs. Redox flow batteries (RFB) are a grid-scale storage technology with the potential to provide a range of services. Desirable characteristics are long cycle life, high efficiency and good energy density. A key challenge for aqueous RFB systems is thermal sensitivity. Operating temperature impacts electrolyte viscosity, species solubility, reaction kinetics and efficiency. Systems that avoid the need for active thermal management while operating over a wide temperature range are needed. A promising RFB chemistry is iron-vanadium (Fe/V) due to the use of low-cost iron. Here we analyze the thermal response of an Fe/V RFB using a zero-dimensional electrothermal model. The model accounts the reversible entropic heat of the the electrochemical reactions, irreversible heat due to overpotentials and the heat transfer between the stack and environment. Performance is simulated using institutional load data for environmental conditions typical of Canadian jurisdictions.
Effect of Heteroatom Doped Graphite Electrode Prepared By Ultrasonication on Energy Efficiency of Vanadium Redox Flow Battery
Authors: Lim Sung Nam , Kim Kiyoung , Woo Ju Young , Song Shin Ae
Published: May 2020

The vanadium redox flow battery (VRFB) is considered a promising candidate for large-scale energy storage because of their advantages such as long lifetime, flexible design, and safety against explosion. However, the high overpotential induced by high polarization and inferior reversibility of its electrode remain challenges to its application. Therefore, several groups have studied methods of electrode surface modification aimed at increasing the number of active sites. There are two widely used approaches to modify the electrode surface, namely, (i) introduction of oxygen-containing functional groups, such as C–OH or C=O, as active sites through thermal treatment, acid treatment, or electrochemical oxidation, and (ii) introduction of an electrocatalyst such as a noble metal, metal oxide, heteroatom, or carbon-based material. Recently, some studies reported effect of dual functionalization onto electrode surface, thus manifesting synergistic effect and improving energy efficiency of VRFB. Representative examples include dual functionalization of nitrogen and metal oxide (WO3 and Mn3O4) or nitrogen and another heteroatom (oxygen and boron).

In this study, we report a simple and easy method for nitrogen-sulfur dual functionalization on the graphite felt surface to enhance the energy efficiency of VRFB via self-polymerization and graft method. In addition, surface properties were investigated using various analytical techniques, and effect of dual functionalization was examined through comparison with the nitrogen functionalized graphite felt
Multielectron Bifunctional Systems for Symmetric Nonaqueous Redox Flow Batteries
Authors: Dumitrascu Adina , Cook Korey , Porath Anthony , Duda Addison , Guarr Thomas F.
Published: May 2020

The introduction of renewable energy generation sources onto the electrical grid is critically dependent on the development of reliable, inexpensive energy storage technology. Redox flow batteries (RFBs) may offer a solution, but many issues remain. For example, aqueous systems are only capable of relatively low cell voltages owing to the limited accessible potential window of water. While other electrochemically useful solvents could provide a larger window, their cost and durability have been problematic. Moreover, the need for an ion-exchange membrane to prevent crossover further increases cost and adds significant cell resistance, especially in nonaqueous systems.

We have previously reported the use of linked electron donor/acceptor compounds D-L-A (where L represents a simple alkyl or aryl linker) to allow the replacement of the expensive ion-exchange membrane with a simple porous separator. Such systems have at least three accessible stable redox states: the “parent” D-L-A state, an oxidized form D+-L-A (catholyte), and a reduced form D-L-A-
(anolyte).

Numerous systems of this type have now been prepared and characterized, yielding nominal cell potentials over 2 V, with promising stability. Several of these systems have the capability of undergoing a net 2e- oxidation as well as a net 2e- reduction, thus providing increased energy density. One such compound is shown below.

The electrochemical properties of several representative linked electron donor/acceptor materials will be described, including progress toward the development of a 4e- system having 9 (nine!) accessible stable redox states. Preliminary data from a prototype RFB device employing such compounds as active materials will also be presented.

Figure 1
Nitrogen-Doped Carbon Material As the Electrocatalyst for Oxygen Reduction Reaction in Rechargeable Zinc-Air Flow Batteries
Authors: Shakeri Hosseinabad Fatemeh , Luong Samantha , Parnian Mohammad Javad , Singh Ashutosh Kumar , Birss Viola Ingrid , Roberts Edward P.L.
Published: May 2020

Rechargeable Zn-air flow batteries are a promising candidate for grid energy storage applications. Zinc-air batteries (ZABs) have low environmental impact, and low cost, which give this system the potential to be applied for large-scale energy storage [1]. Active and durable electrocatalysts in the positive side of the ZABs are important to catalyze the oxygen reduction reaction (ORR) during discharge. N-doped carbons have been reported as a cost-effective catalyst with higher catalytic activity than Pt/C to catalyze the ORR in metal-air flow batteries [2, 3].

In this study colloid imprinted carbons (CICs) and graphene-based materials were applied as the ORR catalyst to improve the performance of the zinc-air battery. Nitrogen doped CICs (NCICs) were prepared by an electropolymerization / carbonization process. Nitrogen doped graphene (NG) were prepared by an electrochemical exfoliation method. The prepared doped carbon materials were characterized by physicochemical characterization methods including SEM and XPS. To evaluate the electrocatalytic activity and the number of electrons transferred in the ORR reaction, cyclic voltammetry (CV) and rotating disk electrode (RDE) experiments were carried out in a three-electrode cell. CV and RDE experiments indicated that NG and NCICs improved the ORR activity.

In this study, a flow-through cell design for the air side was applied to evaluate the performance of the air cathode of the Zn-air flow cell, operating at constant current conditions during discharge.

1]Li, Yanguang, Ming Gong, Yongye Liang, Ju Feng, Ji-Eun Kim, Hailiang Wang, Guosong Hong, Bo Zhang, and Hongjie Dai. "Advanced zinc-air batteries based on high-performance hybrid electrocatalysts." Nature communications 4 (2013): 1805.

[2] Lai, Linfei, Jeffrey R. Potts, Da Zhan, Liang Wang, Chee Kok Poh, Chunhua Tang, Hao Gong, Zexiang Shen, Jianyi Lin, and Rodney S. Ruoff. "Exploration of the active center structure of nitrogen-doped graphene-based catalysts for oxygen reduction reaction." Energy & Environmental Science 5, no. 7 (2012): 7936-7942.

[3] Dai, Liming, Yuhua Xue, Liangti Qu, Hyun-Jung Choi, and Jong-Beom Baek. "Metal-free catalysts for oxygen reduction reaction." Chemical reviews 115, no. 11 (2015): 4823-4892.
Advancing Low Temperature Molten Sodium Batteries By Interfacial Engineering of Ceramic Electrolytes
Authors: Gross Martha M. , Peretti Amanda , Small Leo J. , Percival Stephen , Rodriguez Mark , Spoerke Erik D.
Published: May 2020

Molten sodium batteries show remarkable promise as large-scale energy storage systems, but their widespread deployment has been limited by high operating temperatures (~300°C), which impacts their lifetime, cost, and reliability. Lowering the battery operating temperature promises substantial improvements in these areas, but the lower temperature introduces new challenges to the battery chemistry, especially related to the solid state ion-conducting separators used in these batteries. Traditionally, the high temperature operation has been required to not only maintain high Na+-ion conductivity of solid electrolytes, such as β”-Al2O3 or NaSICON, but also to improve the liquid-solid interfacial wetting of molten sodium on the solid electrolyte. We are focused on drastically reducing the operating temperature to near the melting temperature of sodium (97.8oC), which leads to poor interfacial wetting of the molten sodium. Poor wetting and ineffective charge transfer can dominate battery resistances resulting in a cell-limiting interface. Here, we will describe the rational design of engineered coatings to improve wetting of the molten sodium on NaSICON at low temperatures near 100°C, and therefore improve charge transfer across this critical interface. Enhanced mating of the separator-sodium interface by means of engineered coatings is demonstrated to result in lower interfacial resistance and higher battery performance at increased current densities. This strategy promises substantial advances in the operation of molten sodium batteries at low temperatures and opportunities to expand the utility of these batteries to meet emerging grid-scale needs.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Influence of Ligands on the Cu(I/II) Redox Reaction for Redox Flow Batteries
Authors: Hall Derek M. , Springer Renaldo , Gorski Christopher A. , Lvov Serguei N
Published: May 2020

For meeting ambitious carbon-free electricity goals, low-cost electrical energy storage solutions are needed. Although redox flow batteries are a promising option to satisfy this need, the cost of these devices must decrease before widespread adoption can take place. As the electrolytes are the most significant expense for MW-scale flow batteries, new chemistries derived from inexpensive metals is one approach that may alleviate this bottleneck towards a carbon-free power grid. Here we use an electrochemical approach by applying a rotating disc electrode (RDE) to quantify how ligand chemistries can favorably manipulate the electrochemical parameters of the Cu(I/II) redox reaction, progressing these chemistries forward as potential low-cost electrolytes for redox flow batteries.

In this research, multiple ligands were used to analyze such impacts on aqueous copper metal complexes by using both a platinum and carbon tipped electrode installed into the RDE. Electrochemical Impedance Spectroscopy (EIS), Linear Sweep Voltammetry (LSV) and Open Circuit Potential (OCP) were the three techniques utilized to analyze the effects of these metal complexes. The experimental data was analyzed using the Butler-Volmer and Nernst equations. As step reactions are mostly unknown for these reactions, LSV and EIS data gave insights into what may be occurring at the electrode interfaces. OCP data quantified how different ligands modified the standard electrode potentials of the Cu(I/II) redox reaction.
An Evaluation of Storage for Commercial Scale Demand Charge Management in British Columbia
Authors: Magallanes Laura , Rowe Andrew
Published: May 2020

British Columbia provides electrical service using regulated rates for energy and demand charges. Under this limited market structure, where there is no time-of-use tariff, benefits of behind-the-meter storage are derived from demand charge management or renewable integration. Potential cost savings for a commercial load (a university) using electrical storage for demand charge reductions are investigated. Battery sizes of 500 kW/2 MWh and 1 MW/3 MWh with round trip efficiencies between 80 - 100 % are analyzed. Demand data with 15-minute resolution over one year is tested using simple battery dispatch strategies. Neglecting investment costs, annual operational savings vary from 50 - 70 K$/year depending on battery rating, efficiency and dispatch strategy. Cost savings and value may be increased with optimized storage rating and dispatch strategy.
Electrochemical Detection of Human Antibodies Directly in Whole Blood Using Nanostructured Electrodes.
Authors: Mahshid Sahar Sadat
Published: May 2020

Rapid diagnosis of infectious pathogens in patients can be performed by analyzing specific antibodies produced by the immune system. The ability to specifically capture these antibodies directly in the body fluids such as whole blood, is a huge advancement toward rapid point-of-care diagnostics. We introduce a highly selective strategy for antibody detection based on integrating an electrochemical DNA-based assay with peptide-antibody bioconjugate to specifically capture human antibodies on the surface of electrodeposited nanostructures. We have shown that one-pot detection of macromolecules such as antibodies can be done by sterically inhibiting the hybridization of complementary DNA strand carrying the antibody to the surface bound DNA strand. We also showed that using our electrodeposited nanostructured electrode, we can overcome the limitations of surface toward capturing of peptide recognition, but enhance the inhibition of macro-size molecules for the surface hybridization. Here, we introduce a peptide-assisted electrochemical assay implemented on nanostructured electrode that enables the capturing of real human antibodies directly in whole blood. We improved the linear range and limit of detection by applying the assay using a particular nanostructured platform with tunable roughness. We present the application of the proposed platform to detect HIV-1 human antibodies in real patient samples.
Pt Nanoparticle Sensitized PdNi Nanofibers As Highly Sensitive and Selective Hydrogen Gas Sensor
Authors: Ko Jaehyun , Koo Won-Tae , Kim Il-Doo
Published: May 2020

Detection of different gases in power transformer oil is essential to accurately examine and understand different problems and faults in the transformer system. Especially, during situations like corona discharge and arcing, evolution of hydrogen gas can be hazardous due to its highly flammable and explosive nature. Therefore, development of high-performance gas sensors targeted for hydrogen gas over a wide range of concentrations is very important.

We suggest a facile and effective fabrication method of hydrogen sensing composite material based on palladium and nickel alloy with nanofiber structures originated from electrospinning. PdNi alloy, with further decoration with platinum nanoparticles as catalysts via apo-ferritin templating, shows greatly enhanced sensitivity and response time. Conventionally, Palladium is widely used as hydrogen sensors due to its well-known phase transition to PdHx, α-PdHx at hydrogen concentration below 1%, and β-PdHx at hydrogen concentration above 2%. However, huge volume expansion associated from this transformation limits its lifetime and reduces its long-term performance. In this work, nickel alloying effectively decreases the lattice parameters of the alloy, while increasing the stability during repetitive exposure to high concentration to hydrogen gas. Furthermore, formation of grain boundaries to compensate the lattice contraction induced by nickel alloying, high surface area from its nanofiber structure and gas dissociation and activation properties of platinum nanoparticles improves the sensor’s sensitivity toward hydrogen gas [1]. Nickel in the lattice also acts as pinning points to effectively suppress the grain growth of the alloy during high temperature annealing and reduction processes, which further improves its sensitivity and response time. This facile fabrication and decoration methods allow us to produce a highly sensitive and rapidly responding hydrogen gas sensor with enhanced long-term stability compared to the conventional Pd based hydrogen gas sensors.

Reference

[1] D. H. Kim, ACS
Nano 13, 6071–6082 (2011); doi:10.1021/acsnano.9b02481
Carbon Nanotube Fiber Nanochannel for Ion Passage
Authors: Dangel Gabrielle Rae , Gupta Pankaj , Alvarez Noe T.
Published: May 2020

Nanochannels, such as ion channels, are present in many biological functions and can control ion flow through the channel for cellular function. The trigger of the ion flow can be achieved through changes of pH, voltage, or others variables. Ion channels are important to studying some diseases, however, biological ion channels are embedded in fragile lipid bilayer membranes making them difficult to study. This research is focused on creating a synthetic nanochannel that employs the internal diameter of carbon nanotubes (CNTs) as pores. The CNTs are naturally hydrophobic and studies have shown fast water transport though the CNTs making them a good material for synthetic ion channels. We will assemble 107 channels in parallel to each other within a CNT fiber. This approach will allow easy assembly of the nanochannels for exploration of their capabilities and limitations. This project looks at the diameter correlation to ion dimensions as well as the size selectivity of the nanochannels. Preliminary work has been focused on electrochemical measurements that confirm flow of ions through the CNT nanochannels. Blank samples show current flow close to zero, while samples containing the CNT nanochannel show current flow higher then 4 nA.
Multiplexed Bioanalysis Based on Light-sensitive Electrodes
Authors: Zhao S. , Riedel Marc , Yue Z. , Parak Wolfgang , Lisdat Fred
Published: May 2020

Introduction

Quantum dots (QDs) have become attractive tools in bioanalysis because of their advantageous optical and electrochemical properties. This relates to applications exploiting fluorescence, electrochemiluminescence or photocurrent generation [1]. For the latter case QDs are immobilized on conductive electrodes. By light excitation charge carriers are formed inside the nanoparticles which can be used for photocurrent generation. Signal chains can be constructed when appropriate donor or acceptor components are present in solution. The special feature of such electrodes is that the response is triggered by illumination of the sensing electrode [1]. In this study, a light-addressable photoelectrochemical sensor was built by coupling QDs with oxidases to detect different enzyme substrates.

Results and Conclusions

At first CdSe/ZnS QDs have been immobilised via a dithiol compound on gold electrodes. Two different enzymes, glucose oxidase (GOD) and sarcosine oxidase (SOD) have been deposited on this QDs-electrode at spatially well resolved places. Here small spots have been achieved by a dropping method. A laser beam is moved over the spots to detect photocurrents. Since oxygen can act as electron acceptor at the illuminated QDs the photocurrent is correlated to the oxygen concentration in solution. By action of the enzymes in the presence of the corresponding substrate a competitive situation for oxygen is created in front of the QD layer and thus, the photocurrent decreases [2, 3]. Since this happens in a concentration dependent way, analysis of the enzyme substrate is feasible.

Furthermore, due to the spatially separated immobilisation of the two enzymes, an independent read-out of the two enzyme reactions is possible. The results indicate good lateral resolution and selectivity of the multi-detection system without any crosstalk between the two sensing regions and also without any response at regions, which have not been modified with an enzyme [4].

After that, the possibility of an imaging of the enzyme spot by photocurrent measurement has been studied. When the laser is moved over the spot of GOD with a constant speed, the size of the spot can be determined from the photocurrent - time curve (with a defined moving speed). The photocurrent correlates to different local enzyme activities. Consequently, an imaging of the enzyme activity distribution on the surface has also been achieved by this method.

References

[1] F. Lisdat, D. Schäfer, A. Kapp, Analytical and Bioanalytical Chemistry 405 (2013) 3739-3752

[2] M. Riedel, et al., Chem. Phys. Chem. 2013, 14, 2338-2342.

[3] J. Tanne et al., Anal. Chem. 2011, 83, 7778-7785.

[4] S. Zhao et al., ACS Applied Materials & Interfaces, 2019, Vol. 11 (24), p. 21830-21839
Electrochemically Stimulated Molecule Releaseassociated with Interfacial pH Changes
Authors: Kadambar Vasantha Krishna , Bellare Madhura , Katz Evgeny , Bollella Paolo , Melman Artem
Published: May 2020

External signal-stimulated release of (bio)molecules is used in many biotechnological and biomedical applications1. It has been well documented over decades, resulting in vast group of physical and chemical systems functioning differently and reacting to different signals. Among various molecule-releasing systems responding to different activating signals (e.g.; optical, magnetic, chemical, mechanical, temperature change, etc.); electrochemical systems is one of the most important and interesting research fields. Besides systems controlled by electrostatic attraction/repulsion of molecules at polarized electrode surfaces2,3, more sophisticated systems that are able to release only specific molecules are based on molecular and supramolecular systems can be tailored. In the latter case, selected molecules are included in complex structures assembled at electrode surfaces and disassembled upon electrochemical processes. Some of these systems have electrochemically cleavable covalent bonds (e.g., disulfide bonds), which results in the release of the connected molecules upon redox reaction. While the electrochemical cleavage of bonds based on the redox transformations is a very powerful and successful approach in clean model systems, it may be significantly complicated in the presence of other redox species appearing in complex biological media. Thus, more universal approaches to the electrochemically stimulated cleavage of chemical bonds should be investigated. Herein we report a new linker with a hydrolysable phenolic ester bond at basic pH (~8-10) for electrode modification. Basic pH locally produced at the electrode surface upon electrochemical reduction of oxygen resulted in the hydrolytic cleavage of the phenolic ester bond and release of the immobilized fluorescent dye used as a model compound4.

ǂ These authors equally contributed to the work

References:

1. Katz, E., Pingarron, J. M., Mailloux, S., Guz, N., Gamella, M., Melman, G., & Melman, A. Substance release triggered by biomolecular signals in bioelectronic systems.The journal of physical chemistry letters, 2015, 6(8), 1340-1347.

2. Sempionatto, J. R., Gamella, M., Guz, N., Pingarrón, J. M., Pedrosa, V. A., Minko, S., & Katz, E. Electrochemically Stimulated DNA Release from a Polymer‐Brush Modified Electrode. Electroanalysis, 2015, 27(9), 2171-2179.

3. Masi, M., Bollella, P., & Katz, E. Biomolecular Release Stimulated by Electrochemical Signals at a Very Small Potential Applied. 2019, Electroanalysis. Accepted manuscript.

4. Bellare, M.; Kadambar, V. K.; Bollella, P.; Katz, E. and Melman, A; Electrochemically stimulated molecule release associated with interfacial pH changes Commun., 2019, 55, 7856-7859.
Atomically-Dispersed Functional Materials: From Single-Atom Electrocatalysts to Single-Atom Nanozymes
Authors: Du Dan , Lin Yuehe
Published: May 2020

Nanomaterials with enzyme‐like activities, or nanozymes, have attracted lots of attention recently due to their advantages such as low cost, superior activity, and high stability. The complex structure and composition of nanozymes has led to extensive investigation of their catalytic sites at an atomic scale, and to an in‐depth understanding of the biocatalysis mechanisms.

Single-atom catalysts (SACs) offer the unique feature of maximum atomic utilization, providing a potential pathway to improve the catalytic activity of nanozymes. Recently, we have demonstrated a Fe-N-C single-atom nanozyme (SAN) that exhibits high peroxidase-like activity. The SAN consists of atomically dispersed Fe─Nx moieties hosted by metal–organic frameworks (MOF) derived porous carbon. Due to high single-atom active Fe dispersion and the large surface area of the porous support, the SAN provided a high specific activity which was almost at the same level as natural horseradish peroxidase (HRP). Besides, the Fe-N-C based SAN presented much better storage stability and robustness against harsh environments compared with natural enzymes. The biosensing applications of the SAN and their major challenges will be discussed.

References:

1. L. Jiao, H. Yan, Y. Wu, W. Gu, C. Zhu, D. Du, Y. Lin. When Nanozymes Meet Single-Atom Catalysis. Angew. Chem. Int. Ed. 2019, doi.org/10.1002/ange.201905645

2. C. Zhu, S. Fu, Q. Shi, D. Du, Y. Lin. Single-Atom Electrocatalysts. Angew. Chem. Int. Ed. 2017, 56, 13944-13960.

3. N. Cheng, J. Li, D. Liu, Y. Lin, D. Du. Single-Atom Nanozyme Based on Nanoengineered Fe-N-C Catalyst with Superior Peroxidase-Like Activity for Ultrasensitive Bioassays. Small, 2019, 1901485.

4. X. Niu, Q. Shi, W. Zhu, D. Liu, H. Tian, S. Fu, N. Cheng, S. Li, J. N Smith, D. Du, Y. Lin. Unprecedented peroxidase-mimicking activity of single-atom nanozyme with atomically dispersed Fe-Nx moieties hosted by MOF derived porous carbon. Biosensors & Bioelectronics, 2019, 142, 111495.

5. Y Wu, L Jiao, X Luo, W Xu, X Wei, H Wang, H Yan, W Gu, BZ Xu, D Du, Y. Lin, C. Zhu. Oxidase‐Like Fe‐N‐C Single‐Atom Nanozymes for the Detection of Acetylcholinesterase Activity. Small, 2019, 15, 1903108

6. L Jiao, W Xu, H Yan, Y Wu, C Liu, D Du, Y Lin, C Zhu. Fe-NC Single-Atom Nanozyme for the Intracellular Hydrogen Peroxide Detection. Anal. Chem., 2019, 91, 11994-11999
Tailored Carbon Nanotube-Based Fluorescent Sensors for Cellular Metabolites
Authors: Nißler Robert , Kruss Sebastian
Published: May 2020

Single-walled carbon nanotubes (SWCNTs) are an emerging building block for nanoscale sensors and labels because of their unique photophysical properties. Semiconducting SWCNTs fluoresce in the tissue transparency near infrared (nIR) window (840 – 1650 nm) and do not bleach. Due to their 1D nature small perturbations in their environment strongly affect their fluorescence. The major challenges in using SWCNTS for sensing is on the one side their purification and on the other side a tailored surface chemistry for molecular recognition and photophysical signal transduction. Cellular metabolites such as first messengers are important biomolecules used by cells to exchange both energy and information but up to day there are many such molecules for which no sensors exist. DNA is a versatile macromolecule to functionalize and solubilize SWCNTs. Furthermore, DNA acts as a conformational quantum yield switch, which makes it a good candidate to impart signal transduction. However, different sensing strategies are known, but general recognition capabilities need to be further explored. Here, we present three different approaches with DNA to tailor SWCNT surface chemistry and detect biologically important metabolites.

Firstly, we tuned the sensitivity of ssDNA/SWCNTs against the neurotransmitter dopamine and different plant polyphenols by changing systematically the DNA sequence. In a more rational approach, we engineered DNA strands conjugated to small peptide sequences. In order to enable a ratio-specific linkage, we determined the amount of bound DNA on the SWCNT surface, which was further observed to play an important role in maintaining colloidal stability of the modified ssDNA/SWCNT conjugates. Finally, aptamer-based approaches were used to combine stable surface modification with target selective binding.

For all these approaches we demonstrated via nIR-fluorescence spectroscopy and nIR-fluorescence microscopy that tailoring these nanosensors resulted in an increased specificity against their targets, ranging from small chemical communication compounds (dopamine, H2O2) to cell wall components and secreted enzymes.
Switchable Dopants on Percolation Networks of 2D Materials for Chemiresistive Sensing Applications in Aqueous Environments
Authors: Kruse Peter
Published: May 2020

Permanent doping of semiconductors and low-dimensional structures to modulate their electronic properties is a well-established concept. Even in cases where doping of thin films by analytes (e.g. carbon nanotubes by ammonia) is applied in sensors, it is only reversed by physical removal of dopant molecules, e.g. heating. We have introduced the concept of molecular switches as chemical dopants for thin nanocarbon (or other 2D-materials) films. These molecules can be switched between doping and non-doping states in the presence or absence of a particular analyte. They impart selectivity not only due to their change in doping behavior, but also by physically blocking other potential dopants in the analyte solution from interacting with the conductive film. The resulting structures can act as chemiresistive films.

Chemiresistive sensors are a well-established technology for gas-phase sensing applications. They are simple and economical to manufacture, and can operate reagent-free and with low or no maintenance. Unlike electrochemical sensors they do not require reference electrodes. While in principle they can be made compatible with aqueous environments, only a few such examples have been demonstrated. Challenges include the need to prevent electrical shorts through the aqueous medium and the need to keep the sensing voltage low enough to avoid electrochemical reactions at the sensor. We have built a chemiresistive sensing platform for aqueous media. The active sensor element consists of a percolation network of low-dimensional materials particles that form a conducting film, e.g. from carbon nanotubes, pencil trace, exfoliated graphene or MoS2. The first member of that platform was a free chlorine sensor.[1-3] We are currently working to expand the applicability of our platform to other relevant species, in particular anions and cations that are commonly present as pollutants in surface and drinking water.[4] Our sensors can be incorporated into a variety of systems and will also be suitable for online monitoring in remote and resource-poor locations.

[1] L. H. H. Hsu, E. Hoque, P. Kruse, and P. R. Selvaganapathy, A carbon nanotube based resettable sensor for measuring free chlorine in drinking water. Appl. Phys. Lett. 106 (2015) 063102.

[2] E. Hoque, L. H. H. Hsu, A. Aryasomayajula, P. R. Selvaganapathy, and P. Kruse, Pencil-Drawn Chemiresistive Sensor for Free Chlorine in Water. IEEE Sens. Lett. 1 (2017) 4500504.

[3] A. Mohtasebi, A. D. Broomfield, T. Chowdhury, P. R. Selvaganapathy, and P. Kruse, Reagent-Free Quantification of Aqueous Free Chlorine via Electrical Readout of Colorimetrically Functionalized Pencil Lines. ACS Appl. Mater. Interfaces 9 (2017) 20748-20761.

[4] P. Kruse, Review on Water Quality Sensors. J. Phys. D 51 (2018) 203002.

Figure 1
Development of CNT Film Alignment and Geometries for Neuronal Attachment and Efficient Signal Transfer between Neurons and Electrodes
Authors: Alvarez Noe , Ruhunage Chethani
Published: May 2020

Carbon nanotubes (CNTs) are widely used in neuroscience research for its excellent properties such as high conductivity, electrochemical stability, biocompatibility, mechanical compatibility with tissues, tunable mechanical and chemical properties. CNTs are investigating for its performance as neuronal scaffolds to support neural tissues, neuron growth and differentiation as well as neural stimulating and recording electrodes to control and monitor neural activity in both vitro and in vivo environments. Surprisingly neurons show a better interaction with CNTs when neurons are grown on CNT substrates. Previous research has shown neuronal differentiation on pristine CNT and CNT composites and the alignment of neurites on CNT substrates. Current research focus on interaction of neurons at the interface of pristine CNT films with aligned and cross hatch patterned CNT layers prepared from multi-walled CNT arrays. CNTs have nano scale surface roughness and contribution of alignment of CNTs can retain and adhere neurons without any adhesive proteins. As an initial step to study the interaction of neurons with CNT films, the effect of different CNT alignment on neuron adhesion and neurite development was chosen. PC12 cell line was used to study neuron adhesion and neurite alignment on CNT substrates. It is a commonly used neuronal cell model due to its ability to attain sympathetic neurons characteristics in the presence of nerve growth factor (NGF) in low serum medium. For the study, CNT films were prepared as aligned and in cross hatch pattern on PET sheets. After sterilization with UV irradiation, PC12 cells were seeded and cultured at a density of 20 000 cells/mL on CNT films and allowed to differentiate in NGF medium. For comparison poly l lysine (PLL) coated CNT films were used. Fig 1(Left) shows SEM image of a differentiating PC12 cell on PLL coated film of aligned CNTs and Fig 1(Right) shows SEM image of a differentiating PC12 cell on a crosshatch patterned CNT film with no adhesive coating. While neurites of PC12 cells align with the CNTs on aligned CNT film as states in the literature, pristine CNTs in crosshatch pattern were also able to hold the cells without any surface adhesive coating and allow differentiation of cells. Also PC12 cells tend to show random alignment on crosshatch patterned CNTs and adhere well due to higher degree of porosity and surface roughness. As pristine CNT films were able to hold PC12 cells, the interface properties will be further evaluated by impedance spectroscopy.

Figure 1
Amperometric Detector of Uric Acid in Human Serum Based on Glassy Carbon Electrodes Modified By Gold Nanoparticles and Poly(amidoamine) Dendrimers and Its Application to the Early Diagnosis of Preeclampsia
Authors: Manriquez Juan , Banda-Alemán Jorge Alberto , Sotomayor-Villezcas Viridiana , Zaldívar-Lelo de Larrea Guadalupe , Bustos Erika , Sepúlveda Selene , Sánchez-Fernández León , Sosa-Ferreyra Carlos Francisco
Published: May 2020

Glassy carbon electrodes (GCE) were modified by cysteamine-capped gold nanoparticles (AuNp@cysteamine) and PAMAM dendrimers generation 4.5 bearing 128-COOH peripheral groups (GCE/AuNp@cysteamine/PAMAM), in order to be tested as electrochemical detector of uric acid (UA) in human serum samples. The results showed that concentrations of UA detected by cyclic voltammetry with GCE/AuNp@cysteamine/PAMAM were comparable (deviation <±10%; limits of detection and quantification were 1.7×10-4 and 5.8×10-4 mg/dL, respectively) to those concentrations obtained using the typical uricase-based enzymatic method [1]. Furthermore, results of UA detected by DC-potential amperometry demonstrated that the presence of dendrimers in the GCE/AuNp@cysteamine/PAMAM system minimizes ascorbic acid and serum proteins interferences during UA oxidation, thus improving the electrocatalytic activity of the gold nanoparticles. On the other hand, GCE/AuNp@cysteamine/PAMAM were employed for detecting UA in serum donated by pregnant women having gestational hypertension or preeclampsia (the group of “cases”) and from health pregnant women (the “control” group). The new data confirmed significant differences between the detected UA levels (p<0.001) in the groups of “cases” (6.2±0.5mg/dL) and “control” (4.2±0.9mg/dL), respectively. Therefore, these results demonstrated that the employment of GCE/AuNp@cysteamine/PAMAM - based amperometric detectors as non-enzymatic devices for early diagnosis of preeclampsia constitute a highly reliable route.

References:

[1] A.S. Ramírez-Segovia, J.A. Banda-Alemán, S. Gutiérrez-Granados, A. Rodríguez, F.J. Rodríguez, L.A. Godínez, E. Bustos, J. Manríquez, Analytica Chimica Acta, 812 (2014) 18-25.
(Invited) Highlights from Haldor Topsøe - Dtu Collaboration on Solid Oxide Based Systems
Authors: Hansen John Bøgild
Published: May 2020

Haldor Topsøe A/S and DTU Energy Conversion (previously Risø National Laboratory) has for more than three decades collaborated on development of Solid Oxide Cell based systems. Professor Mogens Mogensen has been a key person in this collaboration and highlights will be provided from some of these efforts:

Sulfur poisoning of SOFC and SOEC stacks

Development and demonstration of multi kW SOFC systems based on methane, landfill gas, methanol and ammonia

Biogas upgrading by SOEC and methanation
(Invited) Production of Liquid Hydrocarbons from Anaerobic Digester Gas
Authors: Hartvigsen Joseph J. , Elangovan S. , Frost Lyman J.
Published: May 2020

OxEon Energy, LLC (OxEon) plans to demonstrate production liquid hydrocarbon fuels using both the methane and CO2 generated in the food waste digester operated by the Environmental Products & Technologies Corporation (EPT). The EPT food waste digester in Burley Idaho sells produced biogas into a natural gas pipeline after separating and venting the bio-CO2. This project will convert the bio-methane to synthesis gas (syngas, as CO & H2) using a non-thermal plasma catalyzed autothermal reformer. To achieve high bio-carbon utilization, high temperature solid oxide co-electrolysis (HTCE) system will electrochemically generate additional syngas from the bio-CO2 combined with steam raised by cooling the Fischer Tropsch (FT) reactor. Syngas from the reformed methane and co-electrolyzed CO2, will be converted to liquid fuels using the FT reactor. Each of the technology components have been field tested independently and will be combined for the first time in this project. The project outcome will be an engineering scale demonstration of liquid hydrocarbon bio-fuel production achieving > 50% conversion to liquids of the biogenic carbon in both CH4 & CO2 produced by an anaerobic digester.

Each of the three technology elements of the integrated engineering test incorporates numerous innovations. The plasma reactor is designed to be fuel flexible, sulfur tolerant, and economically scalable to small, distributed bio-gas resources. It is also very efficient using a low power non- thermal plasma. High temperature electrolysis has demonstrated efficiency at the thermodynamic limit as shown by analysis and testing at DOE and NASA laboratories, and is unique in its ability to co-electrolyze steam and CO2 directly to syngas. The HTCE stacks use innovations proven for the NASA Mars 2020 project which required exceptional ruggedness and effective high temperature seals. The FT reactor enables economical fabrication of smaller size synthetic fuel plants designed to match the scale of distributed renewable biomass resources. This is achieved with large diameter standard piping combined with a novel internal thermal management structure.

The status of the technology elements and the planned engineering demonstration will be presented.

This work is supported by the Bioenergy Technologies Office of the US Department of Energy.
(Invited) Lessons Learned from Operating a Solid Oxide Electrolysis Cell at 1.25 a/cm2 for One Year
Authors: Chen Ming , Tong Xiaofeng , Ovtar Simona
Published: May 2020

Solid oxide electrolysis cells (SOECs) convert electrical energy to chemical energy stored in H2 and/or CO and has a great potential to become a key enabling technology in the transition towards renewables. The key challenges for the successful commercialization of SOEC are the limited long-term durability and cost. To ensure high production rate and hence reduce the investment cost, operation at high current densities needs to be considered. Conventional Ni/yttria stabilized zirconia (YSZ) fuel electrode supported SOEC cells demonstrate acceptable long-term durability when operated at below 1 A/cm2, with a number of tests running for years. These cells suffer however severe degradation when operated at above 1 A/cm2, where the major degradation phenomena are reported to be delamination of the oxygen electrode, crack formation in the YSZ electrolyte, depletion of Ni in the active Ni/YSZ electrode, deterioration of the Ni-YSZ interface, and formation of ZrO2 nano-particles on Ni surface. A large part of the cell resistance increase is associated with the Ni/YSZ electrode. By introducing Ce0.8Gd0.2O2-
d (CGO) nanoparticles into the Ni/YSZ electrode via solution infiltration, we were able to reduce the cell degradation (evaluated based on cell voltages of 0-1000h) from 699 mV/1000h to 66 mV/1000h when operating the cells at 800 oC and 1.25 A/cm2. The CGO nano-particles facilitate the steam splitting reaction at the Ni/YSZ triple phase boundaries (TPB), reduce the electrode polarization and effectively mitigate the microstructural deterioration typically seen in the non-modified Ni/YSZ electrodes. The remaining 66 mV/1000h degradation is mainly associated with formation of a poorly conducting CeAlO3 phase, which is a reaction product between Al2O3 as the sintering aid and the CGO particles on the Ni grains. An effort to break down the CeAlO3 phase was explored, though not successful. Testing the cell with modified Ni/YSZ electrode was extended to one year. A steam supply failure at 4000 h caused certain damage to the cell and resulted in a higher degradation rate in the second half of the one-year test. A counter-balance strategy was successfully tried out by increasing the cell operating temperature to 830 oC eventually. The test was successfully terminated after reaching one year, with cell voltages of 1124 and 1468 mV at the beginning and end of the test, corresponding to an average degradation rate of 40 mV/kh. The current work shows high potential for modifying conventional SOEC cells for use in high current density electrolysis applications.
(Invited) Ultra-Low-Cost Long-Duration Energy Storage Using Solid Oxide Batteries
Authors: Graves Christopher , Jensen Søren Højgaard
Published: May 2020

Solar and wind power are now the lowest cost electricity sources, making an urgent need for low-cost long-duration energy storage technologies to turn these intermittent renewables into on-demand power. Long-duration energy storage is defined as an energy to power ratio of more than 10 h. For some applications, hundreds of hours storage capacity will be needed to balance supply and demand. Available storage systems are inadequate: conventional batteries are too expensive, water electrolysis with fuel-cell re-oxidation is too inefficient, and pumped hydro and compressed air are geographically constrained. Reversible solid oxide electrochemical cells operated like flow batteries have the potential to meet the needs of long-duration storage by using ultra-low-cost storage media. This presentation will include: (1) the advantages of such solid oxide batteries using different storage media than the classical H2/O2/H2O chemistry, (2) experimental demonstration and system design, (3) analysis of the storage requirements for reversible electricity storage applications, and (4) techno-economic analysis of novel solid oxide battery systems compared with conventional batteries and flow batteries.

Figure 1
(Invited) Electrosynthesis in Proton Conducting Solid Electrolytes a) CO2/H2o Co-Electrolysis and b) NH3 Synthesis
Authors: Garagounis Ioannis , Kyriakou Vasileios , Vourros Anastasios , Stoukides Michael
Published: May 2020

In addition to their applications in the construction of fuel cells, hydrogen separators and sensors, solid state proton (H+) conductors can be used as the main component of catalytic and electrocatalytic reactors. Their advantage, compared to low-temperature proton conductors, is that they can operate in a temperature range within which the kinetics of several industrially important catalytic hydro- and dehydrogenation are acceptably fast. In most of the applications of H+ cell reactors in catalytic research, the reaction of interest takes place on the working electrode while the counter electrode serves for the formation of protons from a hydrogen containing compound. These reactors, however, would become more competitive if useful chemicals were produced on both, working and counter electrode [1, 2].

Results on two reaction systems in which both, cathode and anode were properly utilized are presented here. The aim of this study is the electrochemical production of methanol from carbon dioxide and steam, in a co-ionic conducting solid electrolyte cell at atmospheric pressure. Steam and CO2 are introduced at the anode and cathode side, respectively, of a co-ionic (H+ and O2-) conductor. Steam is electrolyzed to form O2 and protons (H+). The latter are transferred to the cathode and react with CO2 to form CH3OH. The second system is an electrochemical Haber-Bosch (H-B) Process [3, 4]. A mixture of steam and methane is fed over the anode (a Ni-composite electrode) and gaseous N2 is fed over the cathode (VN-Fe). Hydrogen extraction from the steam reforming compartment, enhances the thermodynamically limited methane conversions, whereas 5-14% of the protons pumped are converted to ammonia. A protonic ceramic fuel cell is used to recover electricity and separate nitrogen from ambient air by exploiting by-product hydrogen. This process could potentially require less energy and release fewer CO2 emissions than its conventional counterpart.

References:

[1] A.Vourros, V. Kyriakou, I. Garagounis, E. Vasileiou,M. Stoukides, Solid State Ionics, 306 (2017) 76-81.

[2] S.H. Morejudo, R. Zanon, S. Escolastico, I. Yuste, H. Malerød-Fjeld, P.K. Vestre, W.G. Coors, A. Martínez, T. Norby, J.M. Serra, C. Kjølseth, Science, 353 (2016) 563-566.

[3] I. Garagounis, A.Vourros, D. Stoukides, D. Dasopoulos, M. Stoukides, Membranes 9 (2019) 2-17.

[4] V. Kyriakou, I. Garagounis, A. Vourros, E. Vasileiou, M. Stoukides, JOULE, in press, (2019);