bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Techniques for Determining the Number of Electrons Exchanged in Square-Wave Voltammetry
Authors: Fuller Ranon G , Williams Tyler , Schvaneveldt Mark , Rappleye Devin
Published: July 2022

A comparison of square-wave voltammetry models for calculating the number of electrons exchanged in a metal deposition reaction. Square-wave voltammetry is extremely useful for isolating the behavior of a single reaction in a mixed solution of many reacting species. Being able to identify the number of electrons exchanged in a reaction is extremely useful for identifying and characterizing unknown compounds in a process, such as electrorefining, molten salt reactors, and electrolytic oxide reduction. Experiments were conducted for silver deposition on platinum in an aqueous HNO3 solution and for Nickel and Lanthanum deposition on Tungsten in molten LiCl. Diffusion coefficients for Ni2+ and La3+ in LiCl at 700oC are calculated. Accuracy of the soluble-soluble model versus the soluble-insoluble model is discussed. Nucleation dynamics, natural convective and radial diffusive effects, and amount of ohmic drop compensation are all found to impact the resulting calculation for the number of electrons exchanged. A simplified model for determining the number of electrons exchanged under the constraint of well-compensated ohmic drop is proposed and evaluated.
Towards Efficient Direct Air Capture of CO2 Using Computational Modeling
Authors: Cepitis Ritums , Kongi Nadezda , Ivanistsev Vladislav
Published: July 2022

The urgent need to remove CO2 from the atmosphere calls for significant progress in scientific research. Direct air capture (DAC) is a desired technological solution for the removal. Current DAC technology relies on chemisorption, yet a new class of electrosorbent materials has lately emerged with versatile electrochemical and structural properties. This study focuses on the computational investigation of property optimization for electrosorbents, most importantly, understanding binding energy, conductivity, and material porosity. Here we propose density functional-based tight-binding (DFTB) as a promising alternative for higher throughput calculations and provide a comparison with density functional theory (DFT) results.
(Digital Presentation) Evaluating Stability and Performance of Nasicon Membranes for Crossover Mitigation in Aqueous Redox-Flow Batteries
Authors: Modak Sanat Vibhas , Valle Joseph , Kwabi David G. , Sakamoto Jeff
Published: July 2022

Most polymer-based membranes that are used in prototypical aqueous redox-flow batteries (RFBs) do not adequately prevent crossover of small-molecule reactants, causing high rates of capacity fade. Ceramic superionic conductor membranes are an attractive alternative due to their superior abilities to mitigate crossover;1 they can thus enable the deployment of electrolytes containing earth-abundant, small-molecule reactants.2
3 We test the performance and stability of a von Alpen sodium superionic conductor Na3.1Zr1.55Si2.3P0.7O11 (NaSICON) as an RFB membrane by examining its resistance, permeability and interfacial morphology as a function of electrolyte composition and temperature. The resistance of NaSICON is stable for several weeks while immersed in neutral to strongly alkaline ([OH-] = 3 M) aqueous electrolytes, and its permeability to polysulfide-based and permanganate-based small-molecule RFB reactants is negligible compared to that of Nafion. The glassy phase of the NaSICON microstructure at the membrane-electrolyte interface undergoes small amounts of etching while in contact with aqueous electrolytes containing sodium ions, which becomes more extensive when potassium ions are present in the electrolyte, leading in certain instances to complete disintegration of the membrane. We report a ferrocyanide-permanganate flow cell at a pH of 14.5 with a ~ 700 μm-thin NaSICON membrane supporting weeks of cycling with apparently negligible reactant crossover and very low capacity fade (< 0.04 %/day). Area-specific resistance of NaSICON falls dramatically with increasing temperature and decreasing membrane thickness, and a membrane that is 100 µm thick or thinner can enable power densities at above-ambient temperatures that are comparable to power densities of polymer membrane-containing flow cells.

(1) Yu, X.; Gross, M. M.; Wang, S.; Manthiram, A. Aqueous Electrochemical Energy Storage with a Mediator-Ion Solid Electrolyte. Advanced Energy Materials
2017, 7 (11), 1602454, https://doi.org/10.1002/aenm.201602454. DOI: https://doi.org/10.1002/aenm.201602454 (acccessed 2021/03/12).

(2) Wei, X.; Xia, G.-G.; Kirby, B.; Thomsen, E.; Li, B.; Nie, Z.; Graff, G. G.; Liu, J.; Sprenkle, V.; Wang, W. An aqueous redox flow battery based on neutral alkali metal ferri/ferrocyanide and polysulfide electrolytes. J. Electrochem. Soc.
2016, 163 (1), A5150-A5153. DOI: 10.1149/2.0221601jes].

(3) Colli, A. N.; Peljo, P.; Girault, H. H. High energy density MnO4-/MnO42- redox couple for alkaline redox flow batteries. Chem Commun (Camb)
2016. DOI: 10.1039/c6cc08070g.
Triarylamines: Promising Candidates As Aqueous Organic Redox Flow Catholytes
Authors: Farag Nadia L , Jethwa Rajesh , Beardmore Alice E , Grey Clare P. , Wright Dominic S.
Published: July 2022

Redox flow batteries (RFBs) have significant potential in grid-level electrical energy storage, generated by renewable sources such as wind or solar power. Of particular interest in this research are aqueous organic electrolyte systems due to their safety, cost, fast kinetics and greater sustainability compared to the use of conventional inorganic electrolytes or organic solvents. To date this area has been limited by both the solubility and long term cycling stability of organic electrolytes.1 The most difficult challenge in this field is the development of stable organic catholytes that have high redox potentials, high energy density, and high battery efficiency. Triarylamines (TAAs) have the potential to meet these criteria because of the ease of functional group modification allowing for variation of the redox potential, and the low reorganisation energy between the neutral and radical states.2,3

TAAs have previously been explored as catholyte materials in organic non-aqueous RFBs, with studies showing that the redox properties of these easily prepared compounds can be tuned by judicious choice of functional groups at the para positions.4 It was also shown that TAAs have high cycling stability compared to other popular catholytes such as TEMPOL.5 However, TAAs have not previously been used as catholytes in aqueous RFBs.

In this work, a number of TAAs were explored with various substituents in the para-positions of their aromatic rings, with the aim of promoting good aqueous solubility and cycling stability (two of the main selection criteria for any RFB electrolyte). Tris-4-amino-phenyl amine was found to be the most promising candidate, with reversible redox at high positive potentials, ease of synthesis, and reasonable aqueous solubility. Extensive electrochemical investigations using cyclic voltammetry (CV), impedance and full cell cycling were carried out which provide clues as to how the TAA framework can be modified to improve the redox properties for future catholyte applications.

Figure 1: Triarylamine framework containing various substituents and CV of 1mM Tris-4-amino-phenyl amine with a scan rate of 20 mV/s in 1 M HCl with a Ag/AgCl reference electrode, glassy carbon working electrode and platinum counter electrode

1 R. M. Darling, K. G. Gallagher, J. A. Kowalski, S. Ha and F. R. Brushett, Energy Environ. Sci., 2014, 7, 3459–3477.

2 Tohru Nishinaga, Organic Redox Systems, Synthesis, Properties and Applications, Wiley, 2016.

3 J. Wang, K. Liu, L. Ma and X. Zhan, Chem. Rev., 2016, 116, 14675–14725.

4 I. A. V. Romadina, Elena I., K. J. Stevensona and P. A. Troshin, Mater. Chem. A, 2021, 9, 8303–8307.

5 G. Kwon, K. Lee, J. Yoo, S. Lee, J. Kim, Y. Kim, J. E. Kwon, S. Y. Park and K. Kang, Energy Storage Mater., 2021, 42, 185–192.

Figure 1
(Digital Presentation) Investigating the Origin of the Large HER Overpotential of Ti3C2 Using in-Situ/Operando Raman Spectroelectrochemistry
Authors: Johnson Denis , Hansen Kyle , Lai Hao En , Balbuena Perla B. , Djire Abdoulaye
Published: July 2022

MXenes have shown great promise as electrocatalysts for the hydrogen evolution reaction (HER), but their mechanism is still poorly understood. Currently, the benchmark Ti3C2 MXene suffers from a large overpotential. To reduce this overpotential, modifications must be made to the structure through mechanistic studies to increase the reaction rate of the proton/electron coupled transfer steps. Here, we use in-situ/operando Raman spectroelectrochemistry to probe the HER mechanism and environmental changes of the Ti3C2 electrocatalyst during HER. In acidic media, we observed a shift in the termination group from –O– to –OH, consistent with a protonation step followed by a deprotonation step to form hydrogen gas. This mechanism was further corroborated by density functional theory (DFT) calculations. DFT calculations show that protonation of the –O– functional groups followed by binding of a Ti–O–H* with a Ti–H* is the rate determining step, resulting in a large HER overpotential. In neutral media, we observe an overcharging of the structure allowing for the adsorption of water prior to the HER process, which is rate limiting and causes a large HER overpotential. Through DFT analyses, we found that the reduction process in both electrolytic systems substantially increases the Ti–C bond strength for the outer Ti atoms accompanied by a shift of the Ti d-band center away from the Fermi level indicating a much lower reactivity during HER. By combining the experimental and computational results, reaction mechanisms were found for both electrolytic systems. These fundamental insights enable for proper modifications to be made for MXene catalysts to enhance their electrocatalytic performance.
(Invited) Electrochemical Reduction of Carbon Dioxide to Oxygenates and Hydrocarbons
Authors: Yeo Boon Siang Jason
Published: July 2022

Currently, more than 80% of the world’s energy needs are met by burning fossil fuels. Supplies of these fuels are intrinsically limited and will eventually run out. Combustion of fossil fuels also generates carbon dioxide, whose rapidly increasing atmospheric concentration contributes to global warming. One solution for mitigating atmospheric concentrations of CO2 is to electrochemically reduce these molecules into chemicals and fuels. If the energy used for these processes is generated from renewable sources such as solar and wind, we can envisage a chemical production cycle that is closed-loop with net zero carbon emission.

In this talk, we share our recent works related to the development of catalysts for the selective electroreduction of CO2 to oxygenates and hydrocarbons. We shall show the pathway by which CO2 could be converted to 1-butanol, a C4 alcohol. Through a series of control experiments and density functional theory (DFT) calculations, we pinpoint that its C4 backbone was formed from a surface-mediated aldol condensation of acetaldehyde formed from CO2 reduction, rather through the coupling of four CO intermediates. We also discuss how CO2 could be reduced to methanol through a tandem process - CO2 was first reduced to formic acid, and the latter can be reduced to methanol using anodized titanium. For the latter step, experiments and DFT calculations identify Ti3+ and oxygen vacancies (TOV) as the active sites in a vacancy-filling pathway mediated by *H2COOH. We also give screening rules based on the *HCOOH and *H2COOH binding energies alongside TOV formation energies. These can facilitate the high-throughput automated design of catalysts for CH3OH synthesis from tandem CO2 electrolysis. In the last part of our talk, we show how molecules not commonly observed during CO2 reduction such as propylene and other C4-C6 products could be formed.

References:

- W.J. Teh, O. Pique, Q.H. Low, W.H. Zhu, F. Calle-Vallejo and B.S. Yeo. Toward Efficient Tandem Electroreduction of CO2 to Methanol using Anodized Titanium. ACS Catal. 11, 8467. 2021.

- L.R.L. Ting, Y.J. Peng, B.S. Yeo. Mechanistic Insights into the Selective Electroreduction of Crotonaldehyde to Crotyl Alcohol and 1-Butanol. ChemSusChem. 14, 2963. 2021.

- L.R.L. Ting, R. García-Muelas, A.J.M. Martín, F.L.P. Veenstra, S.T.J. Chen, Y. Peng, E.Y.X. Per, S. Pablo-García, N. López, J. Pérez-Ramírez, and B.S. Yeo. Electrochemical Reduction of Carbon Dioxide to 1-Butanol on Oxide-Derived Copper. Angew. Chemie Int. Ed. 59, 21072. 2020.
Switchable CO2 Electroreduction Induced By the Bismuth Moiety with Tunable Local Structures on Graphene
Authors: Zhu Mengnan , Zhang Bowen , Shankar Karthik , Bergens Steven , Luo Jingli
Published: July 2022

Controlling the chemical environment of the atomically dispersed central atoms doped in the graphene lattice is critical to achieve desirable catalytic performances in carbon dioxide reduction reaction (CO2RR), however, how the local structures of non-transition metal-based single atom (SAs) affect the catalytic performances of CO2RR remains less understood. This study reports the immobilization of bismuth single atom catalysts (SACs) on pristine and nitrogenated graphene nanosheets with switchable catalytic selectivity in the carbon dioxide reduction reaction (CO2RR). Based on systematic physical characterizations and electrochemical analysis, it has been demonstrated that the Bi atom coordinated with four adjacent nitrogen atoms (Bi-N-C) selectively produces carbon monoxide (CO) with high selectivity at low overpotential, whereas Bi SACs bounded with carbon atoms (Bi-C) almost exclusively generate formate (FA). Theoretical investigations reveal that the Bi-N-C catalyst displays the lowest activation barrier for the first hydrogenation step of CO2 to produce *COOH, while Bi-C shows the most preferable pathway towards the formation of *OCHO, which is considered as the important intermediate species to generate FA. The controllable product distributions are dictated by the different local structures of Bi centers in Bi-N-C and Bi-C, and such differences could induce distinct electronic properties of Bi centers and subsequently switch the CO2RR products from CO to FA. This work has substantiated the importance of the fine-regulation of the coordination environment of one of the representative p-blocking SAs to steer the selectivity of CO2RR.
(Invited) Tuning Ag Nanoparticle Size for Selective Electrocatalytic Reduction of CO2 to CO
Authors: Alfonso Dominic , Deng Xingyi , Nguyen Phan Thuy Duong , Kauffman Douglas
Published: July 2022

Coinage metals (Au, Ag and Cu) have shown propensity to reduce CO2 under electrochemical condition. For Au and Cu, nanoparticle size has been used as a lever to tune their activity and selectivity and it was found that the competing hydrogen evolution reaction (HER) becomes an issue for small catalyst particles. For the Ag case, which has been shown to produce CO, the effect of the particle size remains a subject of ongoing discussion because of the lack of thorough benchmark studies. In this presentation, we highlight our detailed investigation of electrochemical CO2 reduction on Ag to ascertain whether size variation can be used to tune the reactivity of the catalyst material. Our combined density functional theory, microkinetic modeling, and experiment demonstrate a strong size-dependence for pristine Ag particles in the sub-10 nm range. The modeling reveals that the enhanced activity can be correlated to the population of a moderately high index facet. Experimental results validated these predictions and we identified an optimal particle diameter that balanced selectivity and activity. The availability of synthetic method to make Ag nanoparticle with different sizes and predictive computational methods that factor in the kinetic aspects could potentially enhance future outlook for material design.
(Invited) Effect of Nanostructure and Surface Chemistry on Activity and Selectivity of Cu-Based Electrocatalysts for Carbon Dioxide Reduction
Authors: He Yanghua , Zelenay Piotr
Published: July 2022

Electrochemical conversion of carbon dioxide (CO2) to value-added chemicals using electricity from renewable sources represents a promising path to carbon-neutral fuel cycle and enhanced economic benefits.1 To date, copper (Cu) has been the leading metal electrocatalyst for the electroreduction of CO2 to high-value chemicals: fuels and chemical feedstocks. Although there has been a significant progress in CO2 reduction reaction (CO2RR), the overall CO2RR performance of Cu-based electrocatalysts is still limited by poor selectivity, resulting in a variety of products, such as hydrogen, carbon monoxide, formic acid, methane, and ethylene.2 Enhancing the CO2RR rate relative to the competing hydrogen evolution reaction (HER) and achieving high selectivity for multi-carbon products thus represent the major scientific challenges.

In this presentation, we will summarize our study of innovative Cu-based catalysts aimed at producing high energy-density chemicals, enhancing the understanding of reaction mechanism, and bringing CO2RR closer to practical application. The study has focused on the relationship between the composition and structure of Cu-based electrocatalysts, especially the nanostructure and oxidation states (Cu0, Cu+, and Cu2+), on CO2RR activity. By using a novel approach in the catalyst synthesis we have been able to obtain Cu-based materials with controlled nanostructure, e.g., pore-size distribution, higher surface area, and correlate the catalyst morphology with the selectivity for multi-carbon products. We have associated the formation of CO2RR products with the presence of different active sites on the catalyst surface, a necessary step towards achieving desirable selectivity.

We will also recap the results of a study on the effect of adding a secondary transition metal, e.g., Zn, Ni, and Ag, on electrocatalytic properties of Cu-based catalysts. The rationale behind this approach has been to tune electrocatalytic activity and selectivity via changing the binding strength of the key intermediates, such as *OCHO, *CO, *COOH, *CHO, and *COH.

References

G. Kibria, J. P. Edwards, C. M. Gabardo, C.-T. Dinh, A. Seifitokaldani, D. Sinton, and E. H. Sargent, Adv. Mater. 2019, 31, 1807166.

S. Nitopi, E. Bertheussen, S. B. Scott, X. Liu, A. K. Engstfeld, S. Horch, B. Seger, I. E. L. Stephens, K. Chan, C. Hahn, J. K. Nørskov, T. F. Jaramillo, and I. Chorkendorff, Chem. Rev. 2019, 119, 7610−7672.
Role of Ionic Liquid Electrolytes As a Promoter for CO2 Electrocatalysis As Revealed By Vibrational Spectroscopy
Authors: Ratschmeier Björn , Braunschweig Björn
Published: July 2022

Conversion of CO2 into chemicals and materials with an higher energy content makes CO2 electrolysis interesting for sustainable energy storage. One major strategy is to use electrochemical CO2 reduction reactions (CO2RR) in order to convert CO2 into CO, alcohols and formic acid. However, high overpotentials, competitive hydrogen evolution reaction (HER), as well as low product selectivity and Faraday efficiency, impairs CO2 electrolysis for applications so far. In order to reduce existing overpotentials, the use of room-temperature ionic liquids (RTILs) as promising electrolytes has gained much attention. That is because of their wide electrochemical window, excellent electric conductivity and high CO2 solubility. However, the reaction mechanism that is responsible for the drastically lower onset potentials for CO production from CO2RR, is for imidazolium based RTIL still controversial. Using in operando IR absorption and in situ sum-frequency generation (SFG) spectroscopy, we provide new information on the role of the imidazolium cations for CO2RR. For this purpose, we have studied Pt electrodes in contact with 1-butyl-3-methylimidazolium [BMIM], 1-butyl-2,3-dimethylimidazolium [BMMIM] and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [BMPyrr][NTf2] RTILs that contained 10 to 500 mM H2O. Although, Pt catalysts have clear disadvantages in terms of costs and catalyst performance for CO2RR, because CO forms at low overpotentials but leads to catalyst poisoning and deactivation, the resulting limited number of side reactions renders Pt catalysts interesting for spectroscopic investigations that focus on the molecular origin of the existing low overpotentials. Cyclic voltammetry shows that Pt is active for CO2RR in all three RTILs, with the highest current densities in case of [BMMIM][NTf2]. SFG spectroscopy, demonstrates that CO forms at an onset potential of -0.7 V vs SHE, when [BMMIM] or [BMPyrr] cations and [NTf2] anions are present. This onset potential is independent of the H2O concentration and we propose that CO formation can occur predominantly via an electrostatically stabilized CO2 radical anion. On the other hand, in [BMIM][NTf2] electrolytes a strong dependence on the H2O concentration is observed for potentials <-0.4 V where we show that cations with an active C2 position at the imidazolium ring can act as co-catalysts that enables CO formation through a reactive imidazolium-2-carboxylic acid intermediate.
Understanding Active Sites in Molecular (Photo)Electrocatalysis through Vibrational Spectroelectrochemistry
Authors: Weidinger Inez Marita , Ly Hoang Khoa , Ramuglia Anthony , Borelli Mino , Querebillo Christine Joy , Dong Renhao , Feng Xinliang , Schwalbe Matthias
Published: July 2022

Molecularly defined (photo)electrocatalysts have great potential to perform important energy conversion reactions with high efficiency and selectivity. A particular advantage is their modular design, which allows their reactivity to be tailored to a specific reaction. However, to advance their rational development, a deep mechanistic understanding of the catalytic reactions is required. In situ vibrational spectrochemistry, in particular confocal Raman and infrared absorption spectroscopy, is an extremely powerful method to gain deep insights into the structure and reactivity of electrode-immobilized molecular catalytic systems under operando conditions [1]. Since both vibrational spectroscopic techniques have different selection rules, complementary information about the system under operando conditions can be obtained. In my talk, selected research examples will be used to present the different aspects and features of (photo)electrocatalysis that can be visualized using vibrational spectrochemistry. The target systems presented include, on the one hand, porphyrin- and phthalocyanine-based systems for electrocatalytic oxygen and CO2 reduction [2,3] and, on the other hand, conjugated acetylene polymers for photoelectrocatalytic hydrogen evolution [4]. Spectra evaluation under operando conditions allowed us to demonstrate charge separation and ligand binding within these catalysts, identify the active sites during catalysis, and gain insight into the redox properties, reaction intermediates as well as synergistic effects of dual active sites.

[1] H. K. Ly, I. M. Weidinger, Chem. Commun. 2021, 57, 2328-2342

[2] T. R. Ramuglia, V. Budhija, K. H. Ly, M. Marquardt, M. Schwalbe, I. M. Weidinger, ChemCatChem, 2021, 13, 3934.

[3] H. Zhong, M. Ghorbani-Asl, K. H. Ly, J. Zhang, J. Ge, M. Wang, Z. Liao, D. Makarov, E. Zschech, E. Brunner, I.M. Weidinger, J. Zhang, A. V. Krasheninnikov, S. Kaskel, R. Dong, X. Feng, Nat. Comm. 2020, 11, 1409.

[4] M. Borelli, C. J. Querebillo, D. L. Pastoetter, T. Wang, A. Milani, C. Casari, H. K. Ly, F. He, Y. Hou, C. Neumann, A. Turchanin, H. Sun, I. M. Weidinger, X. Feng, Angew. Chemie Int. Ed. 2021, 60 (34), 18876-18881.
(Invited) Gold Electrodes Emersed from Aqueous Electrolytes: A Kelvin Probe and Infrared Spectroscopy Approach
Authors: Kasdorf Giesbrecht Cristiano , Rohwerder Michael
Published: July 2022

The study of the electric double layer (solid/liquid interface) is of crucial importance for an in-depth understanding electrochemical processes. However, the electrochemical interface (or interphase) is usually buried under a barrier of bulk water which is blocking direct access for most analytical tools. One way to enable direct access is e.g. the emersed electrode concept. For this, electrodes are emersed under potential control from the electrolyte into an inert atmosphere. It was shown in prior works for emersion into UHV [1] and into humid nitrogen [2] that the electrochemical double layer seems to be kept more or less intact during this process. However, thus an electrochemical double layer is obtained that is vertically confined to just one or two monolayers, depending on the humidity of the environment. The Kelvin probe technique can be employed for measuring the resulting electrode potential of such emersed electrodes [3], often providing a linear correlation between applied potentials during the electrochemical polarization and the potentials determined after emersing the sample from the electrolyte [2]. An open question is the role of the amount of water molecules in the double layer on the electrode potential [1,2]. A powerful technique for the investigation of the structure of the water molecules in the double layer region is infrared spectroscopy. Since infrared spectroscopy techniques (using an ATR set-up) can also be applied for characterization of the electrode immersed bulk electrolyte [4], a direct comparison between these two cases is possible.

For this work, NaClO4 and H2SO4 diluted aqueous solutions were used as electrolytes, which both present anions with similar specific adsorption [5]. The Kelvin probe tip was calibrated against an Ag/AgCl/KCl homemade reference electrode [6]. Different atmosphere conditions (relative humidity) were used and their effect on the emersed electrode was investigated by Kelvin probe and IR spectroscopy. Furthermore, studies employing Near Ambient Pressure X-Ray Photoelectron Spectroscopy (NAP-XPS) technique have been conducted in order to detect the presence of anions and cations in the electrochemical double-layer and also for in operando studies with different atmosphere conditions.

Literature:

[1] H. Neff, R. Kötz, J. Electroanal. Chem. 1983, 151, 305.

[2] Z. Samec, B. W. Johnson, K. Doblhofer, Surf. Sci. 1992, 264, 440.

[3] M. Rohwerder, F. Turcu, Electrochim. Acta 2007, 53, 290.

[4] K. Ataka, T. Yotsuyanagi, M. Osawa, J. Phys. Chem. 1996, 100, 10664.

[5] D. D. Bodé Jr., T. N. Andersen, H. Eyring, J. Phys. Chem. 1967, 71, 792.

[6] M. Uebel, A. Vimalanandan, A. Laaboudi, S. Evers, M. Stratmann, D. Diesing, M. Rohwerder, Langmuir 2017, 33, 10807.
(Invited) Ceramic Nano-Heterostructures By Materials Design: Platforms for Sensing Applications – Opportunities and Challengess
Authors: Akbar Sheikh Ali
Published: July 2022

This talk summarizes R&D efforts in the author’s laboratory on the fabrication of oxide nano-heterostructures, exploiting intrinsic material properties, that are highly scalable and do not require use of lithography. One such process creates crystallographically oriented nanofiber arrays of single crystal TiO2 in H2/N2 environment. H2/N2 heat treatment was also used to grow nanofibers on polycrystalline SnO2, showing directional growth on grains with crystal facets. We have also developed a process to create nanofibers of TiO2 on Ti metal/alloys via oxidation under a limited supply of oxygen. In another process, SnO2 nanowires grown from commercial FTO slides using the vapor-liquid-solid (VLS) method were placed in a microwave-assisted hydrothermal chamber where TiO2 nanorods nucleated radially from the SnO2 nanowire cores. We developed yet another interesting nano-structure (nanoislands and/or nanobars) during thermal annealing of an oxide (GDC) on top of another oxide (YSZ) substrate that self-assembles along the softest elastic direction of the substrate. What is common about these structures is that they are fabricated without the use of lithographic techniques and involves simple processes such as gas-phase reactions and stress-driven processes. These nano-heterostructures can be used as platforms for chemical sensing, catalysis, photocatalysis, photovoltaics and biomedical applications. Sensing application presents opportunities and challenges that are presented including an Open access Database Of Resistive type gas Sensors (ODORS) that has been developed and can be used to select suitable sensing materials.
Quantifying the Impacts of Reference Electrode Design on Lifetime and Stability
Authors: Duffy Timothy S , Hall Derek M. , Lvov Serguei N. , Dogan Omer
Published: July 2022

Reference electrodes (RE) are essential to many electrochemical measurements and monitoring technologies. True reference electrodes allow measurement of pH, oxidation-reduction potentials, corrosion potentials, and more. The primary role of these REs is to maintain a stable and predictable potential while withstanding an application environment. When these goals cannot be maintained for a suitable amount of time due to complications like contamination or degradation, a pseudo-reference electrode is often used (e.g., a platinum wire) but diminishes the value of the collected electrochemical data (i.e., potential measurements are no longer traceable to the standard hydrogen scale.)

To limit the use of pseudo-reference electrodes, new RE designs are being produced to be more compatible with specific environments, to be more cost-effective, or to exhibit better potential stability for a longer time. Additionally, the operational lifetime/stability of the RE should reflect its application: a small, disposable reference electrode may only need to be stable for a few hours; a reference electrode for daily lab use may need maintenance once every other week; a reference electrode used in a remote location may need to be stable for months or many years without servicing. RE lifetimes are typically determined a posteriori (from observation) and not predicted at the design phase, which can make the process of designing a new RE very inefficient. In this paper, we will discuss key design considerations that impact the stability and lifetime for true reference electrodes.
(Invited) Gold Nanowire Electronic Skins for Wearable Biochemical Monitoring
Authors: Cheng Wenlong
Published: July 2022

Next generation of electronic devices will be not only flexible but also stretchable, enabling applications impossible to achieve with existing rigid circuit board technologies. This needs new materials and new design principles. Among various materials of choices, gold has advantages of biocompatibity, chemical inertness, facile synthesis/Surface functionalisation and band-gap-matching with a lot of semiconductors materials. In this talk, I will discuss our newly developed standing gold nanowire-based soft electrochemical biosensing platform in the forms of patches, fibers and tattoos. The unique Janus structures, high surface area and facile surface modification offer materials attributes for next-generation wearable biodianostics for real-time monitoring vitals such as glucose, latctate and catitionic ions.
Aminoxyl Catalyzed Electrochemical Ethanol Detection: Development of a New Breathalyzer Using Molecular Catalysis
Authors: Mayer Mikayla N , Rafiee Mohammad
Published: July 2022

Blood alcohol concentration (BAC) is the indicator of alcohol intoxication, and its measurement has emerged as the most common analytical procedure requested by law enforcement. Due to its volatility, ethanol vapor can be detected in breath, and its vapor concentration is proportional to BAC. Currently available instrumentation used for breath alcohol content (BrAC) analysis include gas chromatography (GC) and GC coupled with mass spectrometry, infrared (IR) spectroscopy, and fuel cell based electrochemical sensors. GC and IR spectroscopy devices have some drawbacks such as size, initial cost, and operational expense. Electrochemical sensors are capable of miniaturization and are available as portable and handheld breathalyzers. However, the lack of a single use and disposable sensing element, resulting memory effect and the need for frequent recalibration is the main drawback of currently available electrochemical breathalyzers. There have been few attempts at designing a sensing element to improve the current methods of alcohol detection by electrochemical techniques, all relying on enzymatic alcohol oxidation.1

Herein, we report a proof-of-concept non-enzymatic breathalyzer, harnessing the unique catalytic activity of the aminoxyl radical/oxoammonium redox couple toward alcohol oxidation.2 The relatively low redox potentials of aminoxyls, the mild conditions required for use, and their selective interactions with ethanol are their advantages compared to currently available Pt based breathalyzers. Our functional sensing element consists of a screen-printed electrode in which the graphene oxide-based working electrode is modified with aminoxyl derivatives, of which 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl benzoate (TMB) was the most efficient derivative. Exposing this modified electrode to simulated breath that contains ethanol, while applying the required potential for oxidation of the aminoxyl radical, generates an electrocatalytic current proportional to the ethanol concentration in the breath. These simple, sensitive, durable, and inexpensive electrodes may contribute to the development of a single-use reliable ethanol sensor for personal or law enforcement applications.

Heikenfeld, J.; Jajack, A.; Rogers, J.; Gutruf, P.; Tian, L.; Pan, T.; Li, R.; Khine, M.; Kim, J.; Wang, J.; Kim, J. Wearable Sensors: Modalities, Challenges, and Prospects. Lab Chip
2018, 18, 217.

Nutting, J. E.; Rafiee, M.; Stahl, S. S. Tetramethylpiperidine N-Oxyl (TEMPO), Phthalimide N-Oxyl (PINO), and Related N-Oxyl Species: Electrochemical Properties and Their Use in Electrocatalytic Reactions. Chem. Rev.
2018, 118, 4834.
(Invited) Immunosensing Chip of Indium Tin Oxide Interdigitated Electrode Array
Authors: Lee Dahye , Lee Sunmi , Lee Hae Yeon , Chung Taek Dong
Published: July 2022

We introduce three-dimensional (3D) interdigitated electrode array (IDA), which is a pair of IDAs on the ceiling and bottom in a microfluidic channel. The IDAs comprise of Indium tin oxide (ITO) microband electrodes that are alternatively biased. ITO based IDA can be easily and precisely patterned using conventional etching process to be integrated in a single microchannel in which very small volume of liquid sample is enough to fill. Correspondingly requiring extremely small amount of sample, the proposed strategy offers great opportunity for multiplex electrochemical biosensors with high sensitivity. ITO as an electrode material can make 3D IDA more attractive because the limit of detection goes down owing to substantially low background current. Additionally, this serves as a transparent electrode that allows simultaneous optical detection and thus widens the range of options for electrochemical biosensing chip. There are two key issues toward practical analysis. One is reference electrode that needs to lie as closely as possible to working electrodes to minimize iR drop for precise control of electrochemical potential. It is problematic because reference electrode can be hardly miniaturized to be put inside the microchannel with negligible iR drop due to narrow microchannel, i.e. high resistance. The other is functionalization of ITO surface for efficient plan of glass surface as well as ITO microbands. ITO is chemically inert so that few organic molecules can be anchored and any functional layer on it is readily detached to go away. In this presentation, we introduce two-electrode (2E) system that has appropriate mediator layer on ITO IDA. 2E system consists of only two complementary IDA demanding no reference electrodes while electrochemical potential can be retained owing to the mediators lying on the ITO electrodes. And we suggest a more reliable and versatile way of electrografting to firmly pin various mediators onto ITO surface for sensitive electrochemical immunosensing on a chip.

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(Invited) Electrochemical Biosensors for Label-Free Bacterial Analysis
Authors: Ebrahimi Aida
Published: July 2022

Traditional methods for bacterial detection and analysis are time consuming, labor-demanding, and have limited portability. This presents a significant opportunity for biosensor engineers to develop low-cost devices for bacterial studies. In this talk, I will discuss our recent advances in developing electrochemical biosensing devices for bacterial analysis. The devices enable characterizing cell envelope, metabolic activity, and quorum sensing molecules, and can provide real-time insight into bacterial response to environmental stress, such as drugs. The sensors feature functional materials to achieve specificity and sensitivity for analysis of real samples. Depending on the need, the biosensors are manufactured using a combination of different device fabrication methods, including standard microfabrication, electrodeposition, printing, and laser engraving of plastic and paper. Specifically, owing to compatibility with additive manufacturing and having rich active sites for functionalization, direct laser engraving enables rapid prototyping of low-cost sensors for a wide range of stand-alone diagnostic platforms.
(Invited) Multi-Architectured Lanthanide Doped Nanoparticles for Theranostics
Authors: Vetrone Fiorenzo
Published: July 2022

Light triggered theranostic (therapy and diagnostic) nanoplatforms have gained a considerable attention in recent years. In theranostics, light as an external trigger stands out due to its non-invasiveness, high local precision and temporal resolution. Many such nanoplatforms employ high-energy (visible or UV) light to initiate the individual therapeutic and diagnostic modalities. However, light at these wavelengths suffers from inherent drawbacks such as having little to no penetration in living tissue, inducing autofluorescence from inherent fluorophores or chromophores in tissues and causing photodamage. The use of near-infrared (NIR) light for excitation mitigates such drawbacks associated with high-energy excitation, for example, little to no background autofluorescence from the specimen under investigation as well as no incurred photodamage. Moreover, one of the biggest limitations is that of penetration and NIR light can penetrate tissues much better than high-energy light especially when these wavelengths lie within the three biological windows where tissues are optically transparent. At the forefront of NIR excited nanomaterials are lanthanide doped nanoparticles, which can undergo conventional (Stokes) luminescence and emit in the NIR biological windows. However, unlike other classes of nanoparticles, they can also undergo a multiphoton excitation process where the NIR excitation light is converted to higher energies resulting in anti-Stokes luminescence spanning the UV-visible-NIR regions (known as upconversion). Thus, it now becomes possible to generate upconverted high-energy light (UV or visible) in situ to trigger other light activated therapeutic modalities (i.e. drug release) while using the NIR emission for diagnostics (i.e. bioimaging, nanothermometry). Here, we demonstrate how the luminescence properties (upconversion and NIR) of various lanthanide doped core/shell (and multishell) nanoparticles can be exploited for potential use in theranostics.
Passive Sweat Based Electrochemical Sensor for Rapid Detection of IL-6
Authors: Shahub Sarah , Pali Madhavi , Jagannath Badrinath , Lin Kai-Chun , Muthukumar Sriram , Prasad Shalini
Published: July 2022

Introduction: Portable, on demand biosensing has become a key element for rapid detection of disease, particularly conditions that progress rapidly, such as infections and trauma in response to injury. Severe infections or internal traumas caused by injury can rapidly progress from the moment of onset, often before a patient has started to show symptoms, leading to progressive organ damage. In order to promptly get access to treatment, rapid testing for infection/trauma is necessary for individuals who experience a physical injury. When a person undergoes a traumatic injury, the immune system releases inflammatory cytokines, such as Interleukin-6 (IL6), in response. These cytokines induce inflammation at the site of injury as a defense mechanism against infection and further injury. The inflammatory cytokines are excreted through sweat at levels detectable by an electrochemical sensor. Using a portable, sweat-collecting electrochemical sensor, we have developed a sweat-based sensor that can detect IL6 within ultralow volumes of sweat (1-5 ul) at concentrations as low as 1 pg/ml, for rapid, noninvasive detection of infection and traumatic injury.

Materials and Methods: The electrochemical sensor consists of zinc oxide electrodes on a flexible substrate. IL6 antibodies were immobilized onto the sensor surface using a thiol linker chemistry. Sensor response was measured using Electrochemical Impedance Spectroscopy (EIS) of synthetic sweat dosed with concentrations of IL6 within their physiological ranges. The spike dosing results were verified by a human study, where subjects induced IL6 elevation in their sweat.

Results and Discussion: Sensor response to IL6 spike doses in synthetic sweat showed a dose dependent response to concentration of IL6, as illustrated by the Nyquist plot for sensor response to IL6 in Figure 1. These results were verified by the sensor response to pre- and post-exercise sweat of human subjects, which demonstrates an increase in IL6 levels after 10 minutes of anaerobic exercise for all subjects. This increase in IL6 post-exercise was shown to be significant for all subjects with 95% confidence using a paired T test.

Conclusion: This study presents a noninvasive electrochemical sensor for rapid and early detection of infection or traumatic injury in response to a physical injury. The sensor exhibits a dose dependent response to IL6, a marker expressed at the time of injury. Sensor capability was demonstrated with human sweat pre- and post-exercise, in order to simulate the conditions following a traumatic injury, for which a significant increase in sensor response post-exercise was observed.

Figure 1. Nyquist plot of Electrochemical Impedance Spectroscopy assay of IL6 in synthetic sweat.

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Introduction of Strategic Cost Management for Instrumentation Industry
Authors: Joshi Vidhi , Paresh Shah
Published: July 2022

In this paper Researchers discuss about the Strategic cost management and its various techniques of it. The basic aim of Strategic Cost Management (SCM) is to help the organisation to achieve the continuous advantages with the respect to cost reduction. Strategic Cost Management lays a greater focus on continuous improvement to deliver superior quality product to the customer’s and stake-holders over the long period of the time. In this paper Researchers discuss about the just-In-Time (JIT), Kaizen costing and Quality Costing of Strategic cost management. Nature of JIT, JIT Production, JIT Purchasing, Principles of Kaizen Costing, and Barriers of Quality costing are described in this paper. SCM is a modern cost management approach consisting of changing cost and management accounting system, depending on the change of production system in highly competitive environment.
Investigating the protective effects of estrogen on β-cell health and the progression of hyperglycemia-induced atherosclerosis
Authors: De Paoli Monica , Wood Dempsey W. , Bohn Mary K. , Pandey Arjun K. , Borowitz Dana K. , Fang Susanna , Patel Zinal , Venegas-Pino Daniel E. , Shi Yuanyuan , Werstuck Geoff H.
Published: July 2022

This study examines the effect(s) of estrogen on β cell and cardiometabolic health/function in a novel mouse model of hyperglycemia-induced atherosclerosis ( ApoE−/−: Ins2+/Akita). Using a combination of estrogen deprivation (ovariectomy) and supplementation strategies, we quantify effects on glucose homeostasis and atherogenesis. Our results clearly show a protective role for estrogen on pancreatic β-cell health and function and glucose homeostasis. Furthermore, estrogen supplementation dramatically reduces atherosclerosis progression in both male and female mice.
Simulation of Piano Teaching System Based on Virtual Data Space System and Neural Network
Authors: Yang Liuqing
Published: July 2022

Cloud computing takes the analysis and digital processing technology based on virtual data space as the foundation and core of cloud computing technology development and research, and the significance and importance of data is self-evident. This paper designs a piano teaching system based on the virtual data space system and neural network, which can help users to master and use piano teaching information through the extensive application of this system. The functional test results show that the system fully realizes the automatic allocation of all virtual data spaces in the cloud computing environment and has the function of real-time synchronization with user terminals and applications in the virtual data space. Teachers can directly give lectures to students or give students detailed answers through live webcasting and other methods. Only by using this simple operation mode can they be able to solve the problems of piano teaching very conveniently. For the on-demand video, this paper manages the piano teaching videos by classification, that is, displays this type of video in an interface or table. The improved network recognition performance based on the loss function also achieves better improvement and improvement than the original network. The model has also achieved good performance in training and recognition on datasets in a strong noise environment.
The Third Logarithmic Coefficient for Certain Close‐to‐Convex Functions
Authors: Alarifi Najla M.
Published: July 2022

The logarithmic coefficients γn of a normalized analytic functions f are defined by . For certain close‐to‐convex functions f(z) = z + a2z2 + ⋯, Cho et al. (on the third logarithmic coefficient in some subclasses of close‐to‐convex functions) has obtained the upper bound of the third logarithmic coefficient γ3 when the second coefficient a2 is real. In the present paper, the upper bound of the third logarithmic coefficient γ3 is computed with no restriction on the second coefficient a2.
Mine Geological Disaster Risk Assessment and Management Based on Multisensor Information Fusion
Authors: Zhang Duo , Feng Dongmei
Published: July 2022

Mining excavation is often the main cause of geological disasters in people’s construction activities. The geological disasters have the characteristics of large destruction, wide range of harm, and large loss. In particular, the collapse and slide geological disasters caused by underground mining are particularly prominent, and they have triggered a number of major natural disaster events. Therefore, it is particularly important to assess the exposure to geological hazards in mines. The purpose of this article is to study and analyze the assessment and management of the risk of geological hazards in mines based on multisensor data integration. This paper first introduces the process of multisource information fusion, and in the process of information fusion, the sensor needs to collect signals first, then preprocesses the signals provided by the sensor, and then analyzes the fusion process of D-S evidence theory algorithm and BP neural network algorithm in multisensor. Finally, the deformers in the study area are investigated by multisensor data integration techniques, the deformation and damage features of the deformers in the study area are evaluated, and the risk assessment and vulnerability evaluation of the key slopes are carried out. The experimental results of this paper show that according to the statistics of the distribution of slope disaster points, the geological disasters are mainly concentrated in 10–25°, a total of 361, accounting for 58.1% of the total disaster points. From the point density distribution, geological disasters are most concentrated at 20–30°, and the point density is 35 places/100 km2. The results show that in areas with large slope and height difference, it is easy to form air surface, deformation, and damage, resulting in geological disasters.