bluuebunny/crossref_metadata_2025 huggingface dataset:
Deuterium-Grown Highly-Oriented Boron-Doped Diamond Electrodes
Authors: Dettlaff Anna , Sobaszek Michał , Klimczuk Tomasz , Bogdanowicz Robert
Published: July 2021

Boron-doped diamond (BDD) have attracted increasing attention as a material for electrochemical sensors and biosensors due to its remarkable properties such as its chemical inertness, wide electrochemical potential window, low background current and biocompatibility. Diamond layers are synthesized mainly from a gas phase consisting of carbon, hydrogen, and a dopant source by microwave plasma-assisted chemical vapour deposition (MPACVD). The gas composition during the growth of diamond film has a significant influence on its surface morphology, crystallographic structure, dopant concentration, and superficial non-diamond carbon phases. Thus, the growth conditions of the diamond layer affect the electrochemical properties of the material.

Herein we demonstrate the electrochemical and physicochemical studies of as-grown boron-doped diamond thin-film electrodes, synthesized in a deuterium-rich plasma (BDDD). It is the first report concerning the study of the effect of replacing hydrogen by deuterium during BDD growth. The substitution of hydrogen to deuterium in the gas phase is primarily responsible for the enhanced boron doping and significantly decrease of nondiamond sp2
phase in diamond films. Moreover, the crystallographic structure of BDDD layer is dominated by the (111) configuration while the texture of the BDDH electrode film is oriented along the (220) direction [1].

The proposed boron-doped diamonds synthesized in the deuterium-rich plasma electrodes were revealed to have a higher activity towards [Fe(CN)6]3-/4- and [Ru(NH3)6]2+/3+ redox mediators than BDD electrode grown in hydrogen-rich plasma (BDDH). The peak-to-peak separation recorded on BDDD electrode reaches 60.6 mV, and 59.8 mV in [Fe(CN)6]3-/4- and [Ru(NH3)6]2+/3+ redox couples, respectively. Moreover, in Ru(NH3)6
2+/3+ solution, the apparent heterogeneous electron transfer rate constant k°
app
for the BDDD was equal to 5.84·10-3 cm s-1. The BDDD and BDDH electrodes were also used as an electrochemical sensor for the paracetamol detection. BDDD electrode exhibits better sensing performance towards PCM comparing to BDDH electrode. The value of limit of detectionfor the BDDD electrode was 765 nM, whereas for the BDDH was 2510 nM. The better electrocatalytic behavior of the BDDD electrodes may result from the higher amount of electroactive zones on deuterium-terminated diamond strictly related to (111) crystal facets.

Acknowledgement

This work was supported by the Polish National Science Centre [2020/01/0/ST7/00104]. The DS funds of the Faculty of Electronics, Telecommunications, and Informatics of the Gdansk University of Technology are also acknowledged.

Reference:

[1] A. Dettlaff et al., Carbon [In press]. Doi: doi.org/10.1016/j.carbon.2020.11.096.
Switchable Electron Transfer in Single Thermoresponsive Core-Shell Plasmonic Hybrid Nanoelectrodes
Authors: Flatebo Charlotte , Searles Emily K. , Link Stephan , Landes Christy F.
Published: July 2021

Active control of electrochemical processes at the nanoscale is promising for applications in switchable electronics. It has been demonstrated that stimuli-responsive polymers can serve as logic gates to switch between “on” and “off” states in response to environmental changes at both the macro- and nanoscale. As the majority of these stimuli-responsive polymers are weak polyelectrolytes, metal ions or conductive monomers are often incorporated into the stimuli-responsive matrix for electrochemical applications. However, the incorporation of conductive components may reduce the gating efficacy of these stimuli-responsive materials. In this work, we investigated the efficacy of switchable electron transfer in nonconductive stimuli-responsive core-shell hybrid nanoelectrodes consisting of thermoresponsive poly(N-isopropylacrylamide) grafted from plasmonic gold nanoparticles, termed pNIPAM@AuNPs. Under applied electrochemical potentials, electron transfer to the plasmonic core can be monitored optically through changes in the linewidth and peak position of the longitudinal surface plasmon resonance. Using single-particle dark-field spectroelectrochemistry, we observed that expanded pNIPAM@AuNPs exhibited hindered electron transfer, but, upon polymer collapse, electron transfer substantially increased. We also determined that, although heterogeneous, the extent of electron transfer in pNIPAM@AuNPs was reversibly switched through temperature cycling. Furthermore, we established that the gating efficiency of the polymer is dependent on the core morphology as a result of the size and shape dependent strength of the plasmonic electric field. These results provide insight into reversibly gated electron transfer in stimuli-responsive hybrid nanoelectrodes and suggest that a conductive polymer matrix is not necessarily required to facilitate electron transfer.
Morphological Evolution of Bistable Copper Electrodeposition during Potentiodynamic and Galvanodynamic Measurements on Microelectrodes
Authors: Braun Trevor Michael , Josell Daniel , Moffat Thomas
Published: July 2021

Copper electrodeposition from an electrolyte containing a polyether suppressor and chloride exhibits bistable behavior characteristic of s-shaped negative differential (S-NDR) critical systems. The polyether and chloride form a co-adsorbed adlayer on the electrode that inhibits copper electrodeposition by sterically blocking cupric ion from accessing the interface. At sufficiently negative overpotentials, the adlayer is disrupted and copper electrodeposition occurs freely. In cyclic voltammetry (CV) measurements this behavior manifests as large hysteretic windows. The current response is negligible during the forward sweep until potential-dependent breakdown of the suppressor-halide adlayer occurs. The return sweep exhibits elevated current levels until the blocking layer is reformed at potentials 100s of millivolts more positive than the breakdown potential. When operating at a potential within the hysteretic window, and in an electrochemical configuration with sufficient ohmic resistance, copper electrodeposition exhibits bistable, passive – active deposition on the electrode surface. On macroscale planar electrodes this manifests as random Turing patterns whereas on topographically engineered electrodes, common in electronics manufacturing applications, deposition is localized to the most recessed regions of the interface and progresses in a bottom-up manner.

The inversion associated with NDR behavior is only apparent in CV measurements after post-experimental correction for the iR-drop in the electrochemical cell. Thus, linear or cyclic galvanodynamic sweeps (GDS) offer an alternative measurement method to capture the overpotential inversion associated with critical systems. Electroanalytical measurements on microelectrodes further offer an avenue for exploring systems without significant iR-drop in solution. In this work, CV and GDS measurements on microdisk electrodes are used to explore the influence of additive (suppressor and chloride) concentration on critical behavior during copper electrodeposition. Further, in-situ optical microscopy during electroanalytical measurements is used to correlate characteristics of global potential/current responses to observations of copper growth dynamics. Continuum simulations capture key characteristics, such as hysteresis and overpotential inversion, of CV and GDS measurements as well as the different deposit growth profiles observed for potentiodynamic versus galvanodynamic operating modes.
Spatiotemporal Organization in a Reaction-Diffusion Model for Alloy Electrodeposition
Authors: Lacitignola Deborah , Bozzini Benedetto , Sgura Ivonne
Published: July 2021

Alloy electrodeposition processes have been experimentally shown to exhibit electrokinetic instability that can lead to compositional heterogeneity in the electrodeposit bulk. Inspired by these experimental evidences we consider the DIB model, a morphochemical reaction-diffusion system introduced in [Bozzini et al., J. Solid State Electr.17, 467–479 (2013)] as a mean of understanding the formation of morphological patterns found in the electrodeposition processes. We discuss its rich spatiotemporal dynamics from both the analytical and numerical points of view, revealing interesting classes of morphogenetic scenarios in good qualitative accordance with experiments. The DIB model can in fact undergo to Turing and Hopf instabilities and classical Turing patterns as well as oscillating Turing patterns can be detected. In the Hopf region, we prove the existence of spiral wave behaviour and observe transition to spatiotemporal chaos via spirals break up. The role of cross-diffusion in pattern formation and selection is also discussed as well as some recent extensions of the model to spherical domains.

References

[1] Bozzini, B., Lacitignola, D., Sgura, I., 2013. Spatio-temporal organization in alloy electrodeposition: a morphochemical mathematical model and its experimental validation. Journal of Solid State Electrochemistry 17 (2), 467–479.

[2] Lacitignola, D., Bozzini, B., Sgura, I., 2015. Spatio-temporal organization in a morphochemical electrodeposition model: Hopf and Turing instabilities and their interplay. European Journal of Applied Mathematics 26 (2), 143–173.

[3] Lacitignola, D., Bozzini, B., Sgura, I., 2014. Spatio-temporal organization in a morphochemical electrodeposition model: Analysis and numerical simulation of spiral waves. Acta Applicandae Mathematicae 132, 377–389.

[4] Lacitignola, D., Bozzini, B., Frittelli, M., Sgura, I., 2017. Turing pattern formation on the sphere for a morphochemical reaction-diffusion model for electrodeposition. Communications in Nonlinear Science and Numerical Simulation 48, 484 – 508.

[5] Lacitignola, D., Bozzini, B., Peipmann, R., Sgura, I., 2018. Cross-diffusion effects on a morphochemical model for electrodeposition, Applied Mathematical Modelling 57, 492– 513.

[6] Lacitignola, D., Sgura I., Bozzini, B., Dobrovolska Ts., Krastev I., 2019. Spiral waves on the sphere for an alloy electrodeposition model, Communications in Nonlinear Science and Numerical Simulation 79, 104930.
Synchronization Patterns of Two Coupled Oscillators in a Closed Electrochemical Bipolar Cell
Authors: Tetteh John Anum , Kiss István Z.
Published: July 2021

We investigate the dynamical behavior of the oscillatory electrodissolution of two nickel and hydrogen reduction reaction in a closed electrochemical bipolar cell. In the bipolar setup, two half U cells are separated by an epoxy plate with two embedded nickel wires; the oxidation and reduction reactions take place at the two ends of the same wire. By tuning the concentration of electrolyte in the anode and cathode compartments, the current level and the dynamics of the oscillatory range can be varied without any external resistance. Phase analysis of the chronopotentiometric measurements showed that the potential oscillations of the two nickel anodes are completely in-phase synchronized, and thus strongly coupled, when 1.00 mm diameter electrodes were employed. The complete in-phase synchronization and strong coupling effect was lost as the electrode diameter was decreased from 1.00 mm to 0.25 mm. The synchronization effects were interpreted by the charge transfer resistance of the hydrogen reduction reaction as the main coupling element in the cell. The experiments demonstrate the use of bipolar electrochemical cells for the investigation of coupling and synchronization in chemical oscillatory processes.
(Invited) Hierarchical Defect Engineering for Electrochemical Energy Storage Materials
Authors: Liu Yijin
Published: July 2021

Electrochemical energy storage materials and devices are often designed to be structurally hierarchical and chemically heterogeneous. They are often populated with defects that not only span a broad range of length scales but also could evolve under the operating conditions. Such a multi-length/temporal-scale structural and chemical complexity has a critical role to play in the functionality.

In this presentation, I will talk about our recent studies in the fields of lithium ion batteries (LIB) and hybrid supercapacitors (HSC). For the LIB, I will present the approach of doping elements with low-solubility into LiCoO2, which improves the cathode stability at a deeply charged state [Nat. Energy 4, 594–603 (2019); Chem 6, 2759-2769 (2020)]. For the HSC, I will show the boost of performance through an electrochemical abuse approach, which induces abundant defects in-situ [Joule 4, 673-687 (2020); Adv. Mater. 2006147 (2020)]. These studies largely benefit from advanced synchrotron characterization techniques, which will be highlighted in this talk.
Ultrafine Oxygen-Defective Iridium Oxide Nanoclusters for Efficient and Durable Water Oxidation at High Current Densities in Acidic Media
Authors: Liu Lifeng , Yu Zhipeng
Published: July 2021

Iridium oxide (IrO2) is one of the best known electrocatalysts for the oxygen evolution reaction (OER) taking place in strongly acidic solution. IrO2 nanocatalysts with high activity as well as long term catalytic stability, particularly at high current densities, are highly desirable for proton exchange membrane water electrolysis (PEM-WE). Here, we report a simple and cost-effective strategy for depositing ultrafine oxygen-defective IrOx nanoclusters (1 – 2 nm) on a high-surface-area, acid-stable titanium current collector (H-Ti@IrOx), through a repeated impregnation-annealing process. The high catalytically-active surface area resulting from the small size of IrOx and the preferable electronic structure originating from the presence of oxygen defects render H-Ti@IrOx outstanding OER performance, with low overpotentials of 277 and 336 mV to deliver 10 and 200 mA cm-2 in 0.5 M H2SO4. Moreover, H-Ti@IrOx also shows intrinsic specific activity of 0.04 mA cmcatalyst
-2 and superior mass activity of 1500 A gIr
-1 at an overpotential of 350 mV. Comprehensive experimental studies and density functional theory calculations confirm the important role of oxygen defects in the enhanced OER performance. Remarkably, H-Ti@IrOx can continuously catalyze the OER in 0.5 M H2SO4 at 200 mA cm-2 for 130 hours with minimal degradation, and with a higher IrOx loading it can sustain at such a high current density over 500 hours without significant performance decay, which holds substantial promise for use in PEM-WE.
Alkalinity Promoting Formate Production from CO2 over a Wide Electrochemical Potential Window on a Sns Catalyst
Authors: Zou Jinshuo , Lee Chong Yong , Wallace Gordon
Published: July 2021

Tin-based nanomaterials are attractive low cost electrocatalysts which offers prospect of large-scale CO2 reduction, particularly for selective formate production. However, drawbacks such as large overpotential, low current density and narrow electrochemical potential window render the applicability of this catalyst. Herein, we report the dramatic influence of electrolyte alkalinity in widening potential window for CO2 electroreduction in a flow-cell system based on SnS nanosheets. The optimized SnS catalyst operated in 1 M KOH enables the achievement of a maximum formate conversion Faradaic efficiency of 88 ± 2 % at -1.3 V vs. RHE with the current density of ~ 120 mA cm-2. Alkaline electrolyte was found suppressing the hydrogen evolution across all potentials which is particularly dominant at the less negative potentials, as well as CO evolution at more negative potentials which in turn widens the potential window for formate conversion (>70% at the potential range of -0.5 to -1.5 V vs. RHE). Comparison to SnOx counterpart indicates sulphur acts to suppress hydrogen evolution, although electrolyte alkalinity also plays a role in hydrogen supression. A long term current and formate conversion stability of over 30h at -1.5V vs. RHE was obtained by reducing accumulation of carbonate or bicarbonate and buffered the pH in the KOH catholyte. This study offers new insights into strategy in boosting electrochemical potential window on Sn-based catalyst operable at a wide potential window, and the integration of desirable features of a high current density and long term stable system as demonstrated in this electrocatalytic system offers promise for implementation of large-scale formate production from CO2.
Fast and Reliable Determination of Organic Compounds in Washing Water Samples Using Electrochemical-based Measurements of Chemical Oxygen Demand
Authors: Kalil Haitham , Darwish Eman , Maher Shaimaa , Moalla Sayed , Amin Alaa , Hosny Nasser , Martin Heidi
Published: July 2021

Chemical Oxygen Demand (COD) is referring to the total amount of oxygen used for a chemical oxidation of organic compounds in a water sample. COD stands as an important tool for water safety and water quality standard. Fast-scan cyclic voltammetry (FSCV) has been reported as a simple and a rapid method for electrochemical measurements, particularly for neurotransmitter compounds in brain and biological systems. The main explicit characteristics of FSCV comes from the usage of small volumes of analytes and by adapting carbon-fiber microelectrode as a working electrode with a scan rate of milliseconds. In this research project, FSCV has shown promising results as an alternative method that correlates the COD of traditional measurements. Traditionally, COD is more often estimated using oxidizing agents and toxic chemical reagents that have a serious environmental impact on lifecycle. Unlike traditional oxidation methods, FSCV was used as a powerful an electrochemical tool that allows for measuring COD of Iceberg lettuce washing water samples without using any oxidizing or toxic reagents in few minutes. In addition, FSCV measurements showed a high recovery percentage for both batches, low organic materials, and high organic materials. FSCV provides a fast and reliable platform to measure all chemically oxidizable organic compounds in lettuce washing water samples, which is directly related to COD with an environmentally friendly model based on the oxidation potential.
Effect of Interdigited in the Sensed of Carbon Monoxide Using ZnO Films
Authors: Hernandez Rodríguez Yazmin , García Alejandro Avila , Rubio Gabriel Romero Paredes , Sierra Ramon Peña
Published: July 2021

Carbon monoxide (CO) gas is colorless, odorless and highly toxic. Natural sources account for 40% of the CO in the environment while 40% is the result of human activities. It is produced by the incomplete combustion of fuels and exhaust emission [1]. Zinc oxide (ZnO) is an n-type metal oxide semiconductor (MOS) that has been widely used for gas sensors along many years because of their chemical response to different adsorbed gases, high chemical stability, amenability to doping, non-toxicity, affordability, and relative fabrication simplicity. It has a wide range of electronic, chemical, and physical characteristics and has become a well-known material for commercial sensors because of the sensitivity of its properties under variations of its chemical environment [2,3]. In the present work we use ZnO films for sensing carbon monoxide with the resistive method. The ZnO films were deposited by a sputtering system using radiofrequency (RF), upon substrates of (001) p-type,1.5 x 1.5 cm2 sized silicon. The substrates were washed with a conventional RCA cleaning procedure. ZnO was deposited on the substrate for 45 minutes, obtaining a thickness of approximately 150 nm, under a pressure of 7.1 mTorr, a power of 125 W and an Ar flow of 10%, the blank of ZnO has purity of 99.99%, the deposit was made at room temperature. After the deposition, the metallic interdigitated electrodes were defined by using lithography. Designed electrodes have different distances between the fingers namely: 200, 400 and 800 microns. Also, different metals were used: 50 nm thick aluminum, 25 nm thick gold and 25 nm/50 nm thick gold /aluminum layers.

The gas detection properties were evaluated by measuring the changes of the resistance of the sensing structure under air and CO gas. Results for ZnO structures using two different contact metals. The best response to different concentrations of CO was found with the use of Al as the metallic contact, the difference being greater at high concentrations of CO, and at a relatively low measuring temperature of 240 °C with respect to the other two metal contacts. As expected, the films with a distance between fingers of 800 micros in the interdigitate electrodes were those that presented the greatest response to the gas of interest, this because the surface exposed to gas was larger with respect to the other two designs.

References

[1] Wright J 2002 Chronic and occult carbon monoxide poisoning: we don´t know what we´re missing Emerg Med J 19 386-390.

[2] S. Ghanem, A. Telia, C. Boukaous, M.S. Aida, Humidity sensor characteristics based on ZnO nanostructure grown by sol-gel method Int, J. Nanotechnol. 12(2015) 697–707.

[3] D. Zhu, T. Hu, Y. Zhao, W. Zang, L. Xing, X. Xue, High-performance self-powered/active humidity sensing of Fe-doped ZnO nano array nanogenerator, Sens. Actuators B Chem. 213 (2015) 382.

[4] X. Liu, S. Cheng, H. Liu, S. Hu, D. Zhang, H. Ning, A survey on gas sensing technology, Sensors 12 (2012) 9635.
Influence of Additives Added to Pd-Catalyst Treatment Solutions on Electroless Palladium/Gold Plating on Copper Fine Patterns
Authors: Tanaka Shino , Kato Tomohito , Watanabe Hideto , Yoshida Akihiro , Gunji Takao , Matsumoto Futoshi
Published: July 2021

In order to improve solder joint reliability of Pd/Au layer formed on Cu substrates, the effect of additives added to Pd-catalyst treatment solutions on the solder joint reliability were examined. As the additives, ammonia, ethylenediamine-N,N,N',N'-tetraacetic acid dipotassium salt (EDTA‧2K), glycine, ammonium molybdate tetrahydrate (AMTH) and sodium hypophosphite (SHP) were used. Surface and cross-sectional scanning electron microscopic observation of the Cu substrates after treatment with the Pd-catalyst treatment solutions and Pd layers formed on the Cu substrates and electrochemical measurements of the Pd/Cu were examined to confirm the degree of surface treatment of the Cu surface with the Pd-catalyst treatment solutions and the formation of voids and pinholes in the Cu/Pd interfaces and Pd layers. In addition, after a Au layer was deposited on the Pd layers, the solder joint reliability of the Cu/Pd/Au was evaluated by measuring the share strength of the solder formed on the Au layers. From the results of the solder joint reliability tests, it was found that the SHP additive could improve the solder joint reliability of the Pd/Au layer. The Cu and Pd surfaces treated with the Pd-catalyst treatment solutions containing SHP were relatively flat among those prepared with other additives. The number of voids around the interfaces between Cu and Pd layers in the case of SHP was the lowest among the additives examined. It could be considered that suppression of the formation of voids contributed to the improvement of solder joint reliability of the Pd/Au layer.
Synthesis of Nano-Structured Transition Metal Oxides and Sulfides for Overall Water Splitting and Supercapacitors
Authors: Thompson Kelsey
Published: July 2021

In contemporary society, there are many different ways that energy is used in daily life. From applications that require a high energy density to long term storage in a stable manner, the requirements for energy usage are diverse. Therefore, the greater the number of uses a designed material exhibits the more practical it may be for wide-scale manufacture. Two areas of particular interest for energy applications are fuel cells (to generate energy) and supercapacitors (to store energy). To provide cheaper and more durable alternatives for energy storage electrodes containing CoMoO4, NiMoO4, CoMoS4, and NiMoS4 were synthesized. The electrodes were synthesized through a hydrothermal method using Ni-foam as the substrate then tested as electrocatalysts for water splitting and electrodes for supercapacitors. As an electrocatalyst for hydrogen evolution reaction, NiMoS4 displayed the lowest overpotential of 148 mV with a Tafel slope of 159 mV/dec. On the other hand, CoMoS4 showed the lowest overpotential of 189 mV with a Tafel slope of 78 mV/dec among all four samples for oxygen evolution reactions. In terms of energy storage, the CoMoO4 had the highest specific capacitance of 2652 F/g at a current density of 0.5 A/g with an averaged charge retention of 91% and a Coulombic efficiency of 99% after 10,000 cycles.
Adsorption of Halides on Au (111) Electrode in Aprotic Solvents: AC- Voltammetry, EIS, XPS and Surface-Enhanced Infrared Spectroscopy
Authors: Shatla Ahmed Said , Bawol Pawel Peter , Hegemann Martina
Published: July 2021

Specific adsorption of ions on the electrode surface has a significant impact on the electric double layer (EDL) structure and the kinetics of electrode processes[1]. The ion adsorption at aqueous solution interfaces[2] on various metals has been examined intensively, but much fewer studies from non-aqueous solvents have been conducted[3]. Such studies are important because the metal-solvent [4] and ion-solvent interaction energy [5] depend on the chemical nature of the solvent.

In this study, three organic solvents (propylene carbonate (PC), diglyme (DG), and dimethyl sulfoxide (DMSO)) were investigated for the adsorption of iodide and bromide ions on Au(111) single crystal electrode. This analysis was conducted by using differential capacity measurements, cyclic voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and Surface-Enhanced Infrared Spectroscopy (SEIRAS).

The magnitude of anion adsorption on Au(111) electrode increases in the series of halides I- ˃ Br- due to better solvation [6] and in the solvent order PC ˃ DG ˃ DMSO[7]. As well, the influence of water content on the adsorption rate of iodide on Au(111) electrode in PC and DMSO was studied. This effect, and the much higher adsorption rate in water is explained by the closer approach of the solvated halogen ion to the surface and the resulting stronger interaction of the transition state with the electrode. Quantification of the adsorbed iodide amount from XPS spectra confirms the coverage estimated from the adsorption charge in CVs. During SEIRAS measurements, a bipolar band is observed at around 1805 cm−1 which correlates to the C-O-vibration of PC as reported on silver electrodes from SERS measurements[8]. A stronger electrical field with decreasing potential is observed in absence of iodine leads to higher absorbance of PC molecules on the surface.

Acknowledgments

Financial support by the German Federal Ministry of Education and Research (BMBF) of the “LuCaMag” project (Fkz: 03EK3051A) under the framework of “Vom Material zur Innovation” program is acknowledged.

References

[1] V.V. Emets, B. B. Damaskin, J. Electroanal. Chem. 712 (2014) 62–73

[2] J. Lipkowski, Z. Shi, A. Chen, B. Pettinger and C. Bilger, Electrochim. Acta 43 (1998) 2875-2888.

[3] A. S. Shatla, A. A. Abd-El-Latif, S. Ayata, D. Demir, H. Baltruschat, Electrochim. Acta 334 (2020) 135556.

[4] V.V. Emets, B. B. Damaskin, J. Electroanal. Chem. 600 (2007) 191-204.

[5] B. G. Cox, G. R. Hedwig, et al. Australian Journal of Chemistry 27(1974) 477-501.

[6] M. D. Levi, A. V. Shlepakov, B. B. Damaskin and I. A. Bagotskaya, J. electroanal. Chem. 138 (1982) 1-27.

[7] A. S. Shatla, P. P. Bawol, H. Baltruschat, ChemElectroChem 7 (
2020) 4782-4793.

[8] Hill, I.; Irish, D.; Atkinson, G. Langmuir 2 (

1986) 752-757.
Nanoindentation and Photoluminescence Studies on Hydrogenated Boron Carbon Nitride Thin Films
Authors: Nehate Shraddha Dhanraj , Sundaram Kalpathy B.
Published: July 2021

Compounds in boron-carbon-nitrogen ternary triangle such as diamond (C), cubic boron nitride (c-BN), and boron carbide (B4C) have gained attention due to their covalent bonding, short bond lengths, low atomic mass[1]. These materials exhibit low dielectric values along with excellent mechanical and thermal strength. Boron carbon nitride (BCN) compounds are known to combine unique properties of boron carbide and boron nitride, with the properties being tunable with varying elemental composition and structure. These outstanding properties have made BCN attractive and finds multi-functional applications in anti-wear and protective coatings, supercapacitors, UV detectors, nanobiotechnology and nanomedicine[2]. While addition of small amounts of hydrogen has been proven beneficial for electrical and optical properties in BCN films, the influence of hydrogen on mechanical properties have not yet been reported.

In this study, BCN thin films are deposited using RF magnetron sputtering with varying hydrogen/nitrogen gas flows and substrate deposition temperature. Dual target sputtering from B4C and BN targets is performed to deposit BCN thin films. The chemical composition, hardness, Young’s modulus and photoluminescence properties of BCN films are measured as a function of gas flow and substrate temperatures. Hardness of the BCN films range between 6 – 22 GPa and Young’s modulus between 125 – 140 GPa. Photoluminescence (PL) studies are performed at room temperature and 77K. PL peak shifts are observed in BCN films deposited at different substrate temperatures.

References

[1] Zhang H, Yao S, Widom M. Predicted phase diagram of boron-carbon-nitrogen. Physical Review B. 2016;93:144107.

[2] Nehate S, Saikumar A, Prakash A, Sundaram K. A review of boron carbon nitride thin films and progress in nanomaterials. Materials Today Advances. 2020;8:100106.
(General Student Poster Session Winner - 2nd Place) Synthesis and Comparative Electrochemical Study of Mixed Metal Oxides Derived from Hydrotalcites Modified with Copper (II) and Nickel (II)
Authors: Granja Claudia Patricia , Aperador Chaparro William , Gómez Cuaspud Jairo Alberto , Mora Jorge , Morales Jimmy Alexander
Published: July 2021

At present, the use of heterogeneous catalysts together with environmentally friendly methodologies has been increasing for the synthesis of value-added products.[1] Schiff bases (SB) and their derivatives are very versatile compounds of great importance in the fine chemical industry since they are widely used in various chemistry fields such as, pharmaceutical, clinical, pharmacological, electrochemical, catalytic, photochemical and luminescence. [2-4] On the other hand, the use of mixed metal oxides (MMO) derived from hydrotalcites (LDHs) as catalysts has been increased in organic chemistry. In this work, we synthetized, characterized, and employed MMOs modified with Cu (II) and Ni (II) as catalyst in the synthesis of SB derived from 2-aminothizoles and aromatic aldehydes. The MMOs synthetized were labeled as NixMMO and CuyMMO (x and y, denotes the percentage of substitution of Mg (II) ions by Ni (II) or Cu (II) ions). The electrochemical behavior of these MMOs were determined by cyclic voltammetry and chronoamperometry using a system of three electrodes: Ag/AgCl electrode (reference electrode), Pt wire (counter electrode) and carbon paste electrode (CPE) modified with MMOs (working electrode) in an electrochemical cell. The analysis was carried out employing NaOH (0.1 mol L-1) and NaCl (0.05 mol L-1) as electrolytic. [5] The electrochemical behavior of these MMO were compared with the catalytic results obtained in the synthesis of SB determining the influence of the metal substituted on the catalysts.

[1] Vargas, J. M., Henrique, L., Morelato, T., Ortega, J. O., Boscolo, M., & Metzker, G. (2020). Upgrading 1-butanol to unsaturated, carbonyl and aromatic compounds: a new synthesis approach to produce important organic building blocks. Green Chemistry, 22, 2365-2369

[2] Muhammad, A. R., Necmi, Dege., Onur, E. D., Tuğgan, Ağar., & Sajjad, H. S. (2020). Synthesis of two new Schiff bases; crystal structure, Hirshfeld surface analysis, density functional theory and molecular docking. Molecular Structure, 1226, 129330.

[3]Revenga, M., Robledo, S., Martínez, E., González, M., Colina, A., Herase, A., Parientea, F., & Lorenzo, E. (2020). Direct determination of monosaccharides in honey by coupling a sensitive new Schiff base Ni complex electrochemical sensor and chemometric tools. Sensors and Actuators B: Chemical, 312. 127848.

[4] Maza, S., Kijatkin, C., Bouhidel, Z., Pillet, S., Schaniel, D., Imlau, M., Guillot, B., Cherouana, A., & Bendeif, E. (2020). Synthesis, structural investigation and NLO properties of three. Journal of Molecular Structure, 1219, 128492.

[5] Aguilar, V., Gonzalez, I., & Valente, J. S. (2011). Comparative Electrochemical Study of MgZnGa and ZnGaAl Hydrotalcites. ECS Transactions, 36, 247–256.
Conductive MOF/Polymer Composite Electrode with Enhanced Capacitance for Supercapacitors
Authors: Pokharel Jyotshna , Gurung Ashim , Zhou Yue
Published: July 2021

Activated carbons, carbon nanotubes, and crosslinked graphene have been extensively used as electrode materials in electrochemical double-layer capacitors (EDLC). Metal-organic frameworks (MOFs) whose surface area exceeds that of the activated carbon makes MOF as a potential electrode material. However, MOFs is conventionally thought to have very poor electrical conductivity, preventing its use as an electrode material for the EDLC applications. Here, we present a facile hydrothermal synthesis and carbonization of Cu based metal-organic framework and polymer fibers. The novel hierarchical porous carbon thus formed showed rich ionic storage unit and conductive pathway delivering excellent specific capacitance of 400 Fg-1 at the current density of 0.05 Ag-1. This novel carbon-based material can contribute towards development of low-cost, high energy/power density supercapacitors.
Controlling H-Bond Strength Via Proton-Coupled Electron Transfer
Authors: Baek Kiyeol , Choi Hyejeong , Smith Diane
Published: July 2021

An important goal in supramolecular chemistry is the development of stimuli-responsive systems in which supramolecular assembly is controlled by external signals. One way to do this is to use electron transfer to perturb the strength of H-bonds. The principle is straightforward: reduction that increases negative charge on a H-acceptor (A) or oxidation that increases positive charge on a H-donor (D) will increase the strength of a H-bond. However, oxidation or reduction can also lead to full proton transfer, resulting in an increase in unfavorable secondary interactions that counteracts the effect of the initial electron transfer. But, with proper design, proton transfer can lead to an increase in favorable secondary interactions, enhancing the effect of the initial electron transfer. The success of the latter strategy is demonstrated with the 3 H-bond DAD array, 1, that contains a N-methyl-4,4'-bipyridinium redox couple.1 In CH2Cl2, 1 forms a three H-bond dimer with ADA array, 2, with a modest Kb of 500 M−1 due to the unfavorable secondary interactions. Initial CV studies show that two electron reduction of the bipyridinium increases the binding strength by 2×105 giving a very strong Kb of ~108 M−1. This value is consistent with expectations for a DDD-AAA H-bond complex, strongly suggesting that electron transfer not only creates an ionic H-bond but also leads to proton transfer and conversion of the secondary interactions from unfavorable to favorable. In this presentation, the results of a full investigation of this system will be reported, including UV-vis spectroelectrochemical studies that support proton transfer and NMR studies of possible 1-1 and 2-2 homodimerization. Furthermore, theoretical CV’s that include, if needed, homodimerization will be fit to the experimental CV’s to provide a more exact measure of the binding enhancement in this system.

1H. Choi, K. Baek, S. Toenjes, J. L. Gustafson, and D. K. Smith, J. Am. Chem. Soc.
2020, 142, 17271-17276. DOI: 10.1021/jacs.0c07841

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A Wearable Electrocardiography Sensor-System with Three-Dimensional Stretchable Interconnects
Authors: Zhang Anan , Tessier Alexandre , Williams Chris Martin , Ameri Shideh Kabiri
Published: July 2021

The recent COVID-19 pandemic has proven that low-cost wireless wearable medical device which offer reliable continuous health monitoring can be extremely valuable and game changing tools in early diagnosis, control and management of contiguous disease. Current commercial wearables are not reliable and accurate enough for medical diagnosis, further they are rigid, bulky, and expensive.

Here we present a skin-mounted, low-cost, soft and stretchable wearable electrocardiography (ECG) sensor-system which enables continuous and wireless ECG recording. The ECG sensor-system consists of low-cost, disposable, soft and stretchable, carbon-based electrodes patch; and a reusable, front-end and wireless circuits patch. The sensor patches are made by our developed low-cost scalable manufacturing method of spray-printing, on breathable, conformal, stretchable medical adhesives. The softness and thinness of electrodes patch ensure the conformability of electrodes to skin, maximizes the quality of sensing by decreasing the electrode-skin impedance and consequently improving the signal to noise ratio (SNR) and furthermore offer comfort to users. The reusable ECG circuit patch consists of three-dimensional stretchable/deformable interconnects (SDI) integrated with off-the-shelf integrated circuit components. SDI is made of microfluidic channels filled with liquid metal (LM). Unless other reported liquid metal based interconnects, SDI has been designed in 3D form to increase the stretchability and make it robust to deformations in all three x, y and z axis. The sensor-system is also waterproof and the developed disposable sensors are breathable and more comfortable than commercial wet gel electrodes. The recorded ECG signal can be sent to a personal device such as tablet and laptop wirelessly and be displayed in real-time. The developed sensor-system is a platform that can be applied for the construction of various types of sensor-systems with other sensing capabilities.

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An Economic Hypochlorous Acid Maker for Covid-19 Control
Authors: LI Liyu
Published: July 2021

It has been shown that HOCl can inactive numerous viruses, including Corona-19 Viruses in less than one minute. HOCl inactivates viruses, bacteria, endospore and fungi whilst being safe for human tissues with a 99.999% elimination rate. HOCl is listed on the United States Environmental Protection Agency’s List for Disinfectants for Use Against SARS-CoV-2 (Covid-19). It can be used conveniently as hand sanitizer, surface cleanser, food washing solution, fogging solution for school classrooms, buses, shops, restaurants, hotels, offices, theaters, airports, trains, gyms, etc. It is a green, safe, environmentally friendly and fully biodegradable liquid which acts as a very powerful antimicrobial and sterilizing solution.

Most consumers purchase pre-made HOCl products produced in a large manufacture site. The pre-made HOCl hypochlorous acid products in the market are very expansive, mostly due to high cost for packaging, transportation, distribution, storage, and in-stability of the product, which normally has a lifetime of 6 -12 months. The capacity of current on-site HOCl generation products is either too big, or too small, only economical for large quantity consumers or single household uses. Due to the Corvid-19 pandemic, there is a strong need for a safe, on-site, on-demand medium-sized HOCl generation product, which uses only non-hazardous household chemicals and has a production capacity of about 10 gallons per day. Here we report our recent development of a compact and low cost HOCl on-site generator for daily disinfection applications against Corvid-19 virus. Compared to other products on the market, which normally use >2 g/L NaCl solutions, our device uses only 0.4 g/L NaCl solution. This is highly desired for environment fogging disinfection applications. Other advantages of our device include: 1) no noticeable Cl2 gas generation during HOCl production; 2) tap water can be used directly without softening treatment; 3) produce very stable products, with 90% HOCl Stability: > 100 days.

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Smartphone-Based Microscopy with Silicone Lens Embedding Nanostructured Photonic Components
Authors: Barillaro Giuseppe
Published: July 2021

In this work [1], the moldless preparation of a silicone (i.e., poly(dimethylsiloxane), PDMS) lens embedding nanostructured porous silicon (PSi) optical components is discussed, along with its application to smartphone-based microscopy in biology and medicine.

A nanostructured PSi surface is used to redirect a droplet of uncured silicone into a lightweight, high-magnifying lens (10 mg mass and 4.7 mm focal length). Geometrical and optical properties of the lens are easily controllable by tuning of the nanostructure features (i.e., thickness and porosity of PSi). Design of the PSi layer as an optical component (e.g., distributed Bragg reflector, rugate filter, resonant cavity) further enables to embed nanostructured optical elements in the lens, so as to select the light transmitted through the lens itself. The fabrication process of the lens has high reliability (yield >95%), low-cost (0.01 $).

As proof of concept applications, using a single monolithic lens/filter element self-adhered to a commercial smartphone camera we will discuss: fluorescence imaging and counting of live/dead isolated human cancer cells with high magnification and rejection of the excitation light; selection of a narrow wavelength band from the emission spectrum of a fluorescent dye; changing of the color of a white light emitting diode (from red to blue) through shaping of the diode emission spectrum.

[1] Mariani, V. Robbiano, R. Iglio, A. A. La Mattina, P. Nadimi, J. Wang, B. Kim, T. Kumeria, M. J Sailor, G. Barillaro, Moldless Printing of Silicone Lenses with Embedded Nanostructured Optical Filters, Adv. Funct. Mater., 1906836 (2019).
Overdischarge Analytics of Li-Ion Cells Using a Reference Electrode Configuration
Authors: Zhou Hanwei , Fear Conner , Juarez Robles Daniel , Jeevarajan Judith , Mukherjee Partha P.
Published: July 2021

Although lithium-ion batteries are driving the prosperity of the rechargeable world, safety catastrophes under extreme conditions are still one of the main challenges. Overdischarge is a common electrical abuse that may arise in a Li-ion battery pack when an extreme cell voltage imbalance occurs. The electrode cross-talk under an overdischarge scenario is still an open question. To fill this gap, Li-ion pouch cells with reference electrode configurations are fabricated to decouple anode and cathode characteristics from full cell performances. Electrode potentials vs. Li/Li+ at discharge, relaxation and charge phases are measured and interpreted. State of health deterioration is tracked through temperature, volume and impedance monitoring. Surface microscopic characterizations are implemented to explore morphologies and chemical states of electrodeposition. Electrolyte transformation and gas generation are determined using the gas chromatography-mass spectroscopy technique. This study reveals an implicit cathode-centric degradation mechanism in overdischarge extremes, providing a new perspective on overdischarge mitigation strategies.
Understanding Li-Ion Cell Thermal Runaway through in Situ Measurement of Temperature Distribution
Authors: Huang Shan , Du Zhijia , Zhou Qian , Snyder Kent , Liu Siyi , Zhang Guangsheng
Published: July 2021

Thermal runaway is a critical safety challenge for Li-ion cells, characterized by rapid temperature rise and potentially rapid energy release. Numerical modeling studies revealed that temperature distribution in Li-ion cells is highly non-uniform during thermal runaway1
,
2. However, there is a lack of experimentally measured temperature distribution results for model validation or insightful understanding of thermal runaway. Here we report development of a Li-ion cell with multiple embedded thermocouples and in situ measurement of its temperature distributions during thermal runaway.

As schematically shown in Figure 1, seven micro thermocouples are embedded inside a 2.5 Ah Li-ion pouch cell, enabling in situ measurement of temperatures at different locations. Various testing is performed, including nail penetration testing using a 3 mm-diameter stainless steel nail to trigger thermal runaway. Following our earlier practice3, the nail speed utilized is lower than 0.1 mm/s and the voltages between the nail and cell tabs are monitored.

Figure 2 shows the spatial temperature distribution along the centerline during 5C (12.5 A constant current) discharging in comparison with that during thermal runaway as triggered by slow nail penetration. It can be seen that the maximum temperature rise during 5C discharging is about 25 °C and that local temperatures closer to tabs are always slightly higher than those away from tabs. In comparison, maximum temperature rise during thermal runaway is up to 700 °C. More interestingly, the pattern of spatial temperature distribution changes dramatically and is highly non-uniform during thermal runaway. Before 238s, there is little temperature rise and temperature distribution is quite uniform, indicating very slow heat generation near the nail. At 240s, the rise of local temperature closest to the nail is more than 400 °C while the rise of local temperature near the tab is only 20 °C, indicating highly non-uniform temperature distribution and rapid heat generation near the nail. Note that temperature gradient is directionally opposite to that during 5C discharging. Local temperature farther away from tabs but closer to penetration location rises more and faster than that closer to tabs. All of the local temperatures then continue to rise while the temperature gradient becomes smaller, suggesting propagation of thermal runaway from nail penetration location to entire cell. Such detailed spatial-temporal experimental results will help in better understanding of thermal runaway behavior and the development of safer Li-ion cells.

References:

W. Zhao, G. Luo and C.Y. Wang, Journal of The Electrochemical Society, 162, A207 (2015).

W. Zhao, G. Luo and C.Y. Wang, Journal of The Electrochemical Society, 162, A1352 (2015).

S. Huang, X. Du, M. Richter, J. Ford, G. M. Cavalheiro, Z. Du, R. T. White and G. Zhang, Journal of The Electrochemical Society, 167, 090526 (2020).

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Understanding the Multi-Scale Effects of Li-Ion Cell Destruction By Locally Induced Heating of Cylindrical Cells
Authors: Holloway Justin , Maharun Muinuddin , Pathan Tanveerkhan , Loveridge Melanie J
Published: July 2021

Without suitable design, lithium ion cells within electronic devices can be exposed to localised heating causing a thermal runaway event. This study focussed on determining the localised temperatures that would lead to venting and thermal runaway of a cell as well as to monitor the gases exhumed by these events. Commercially available 18650 cylindrical cells were monitored while being exposed to localised temperatures up to 250 °C. These temperatures were then applied while the cell was charged to simulate a heating scenario by the device electronics. The resulting damage to the cell was evaluated using x-ray tomography, mechanical testing and microscopy. Gases were analysed using a mass spectrometer. This work elucidates a particular failure mode of lithium ion cells allowing for a better understanding of battery safety and associated system design improvements. Additionally we anticipate this approach to facilitate further regulatory approvals for consumer electronics.