bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redox and Coordination Chemistry of Chalcogenophenes
Authors: Shida Naoki , Nishiyama Hiroki , Zheng Feng , Ye Shuyang , Seferos Dwight S. , Tomita Ikuyoshi , Inagi Shinsuke 
Published: May 2020

Chalcogenophene is a five membered aromatic ring containing group 16 elements, and widely used for the design of small molecule or polymer based organic devices. In this work, we report a thorough discussions on the electrochemical redox chemistry of chalcogenophenes, with special emphasis on tellurophene (N. Shida, H. Nishiyama, F. Zheng, S. Ye, D. S. Seferos, I. Tomita, S. Inagi, Communications Chemistry, 2019, 2, 124.).
2,5-Diphenyl tellurophene (PT) was first chosen as a model molecule for this study (Figure). By employing spectroelectrochemstry, electroorganic synthesis and quantum simulations techniques, it was revealed that PT change their redox behavior in two different modes: one electron oxidation to generate radical cation in weakly coordinating electrolyte or two electron oxidation with coordination of anions and solvents onto tellurium in coordinating electrolyte. The strong interaction between anions (ClO4, BF4, PF6) or neutral donor (MeCN) with tellurium in oxidized tellurophenes became evident for the first time, which implies that the positive charge is not delocalized in the conjugated π-system as is usually expected for the conjugated molecules. By using analogous molecule with larger π-system, i.e., 2,5-(9,9-dimethylfluorene)tellurophene (FT), coordinated species and radical cation were generated simultaneously. These finding will lead further understanding of the fundamental redox chemistry of chalcogenophenes.

Figure 1
Dissolution Stability of Photoanodes and Co-Catalysts in Photoelectrochemical Water Splitting
Authors: Knöppel Julius , Kormányos Attila , Mayerhöfer Britta , Hofer André , Speck Florian Dominik , Bachmann Julien , Thiele Simon , Cherevko Serhiy 
Published: May 2020

In the future energy scenario, production of hydrogen is a promising solution for the storage of renewables. Photoelectrochemical water splitting with integrated devices can be engaged for the production of hydrogen with the advantage of less space consumption and saving power lines to the production site. Current devices have already come close to the efficiency of an electrolyzer coupled to a solar cell [1]. However, to be profitable in commercial use several challenges have to be resolved. One of the most pressing issues is photostability of materials during operation. Even though photoelectrodes are able to reach lifetimes of several days in lab conditions, it is still a long way until real device lifespans of several years are possible.
While efforts in the field of photoelectrochemical water splitting are mainly focused on achieving higher activity, research on stability is still at the very beginning. Evaluation of photostability is typically done by rather short (only few hours) chronoamperometry measurements and post mortem analysis. One option to study degradation processes in-situ is to use on-line inductively coupled plasma mass spectrometry (on-line ICP-MS) which became available recently and revealed photocorrosion of WO3 [2] and BiVO4 [3].
In this study, we aim to achieve a better understanding of the key factors driving photocorrosion. It has already been shown, that WO3 exhibits significant differences in faradaic efficiency towards the oxygen evolution reaction (OER) in various electrolytes [4]. One reason behind this behavior might be degradation processes driven by the electrolyte. To study the effect of electrolytes on stability, dissolution of spray-coated WO3 films was investigated in four electrolytes (HClO4, H2SO4, HNO3 and CH3SO3H). Additionally, the influence of protective iridium co-catalyst layers on stability, synthesized in various thicknesses by atomic layer deposition (ALD) was explored.
1. Cheng, W.-H., et al., Monolithic Photoelectrochemical Device for Direct Water Splitting with 19% Efficiency. ACS Energy Letters, 2018. 3(8): p. 1795-1800.
2. Knöppel, J., et al., Time-resolved analysis of dissolution phenomena in photoelectrochemistry – A case study of WO3 photocorrosion. Electrochemistry Communications, 2018. 96: p. 53-56.
3. Zhang, S., et al., Dissolution of BiVO4 Photoanodes Revealed by Time-Resolved Measurements Under Photoelectrochemical Conditions. The Journal of Physical Chemistry C, 2019.
4. Reinhard, S., F. Rechberger, and M. Niederberger, Commercially Available WO 3 Nanopowders for Photoelectrochemical Water Splitting: Photocurrent versus Oxygen Evolution. ChemPlusChem, 2016. 81: p. 935-940.
Spectroelectrochemistry of Explosive Aliphatic Nitro Compounds
Authors: Holubowitch Nicolas , Budimir Zachary , Crabtree Cameo 
Published: May 2020

The spectroelectrochemical behavior of non-aromatic explosive compounds, namely two nitramines (RDX and HMX), a nitrate ester (PETN), and a plastic explosive composite (Semtex 1A) in acetonitrile is reported. The electrochemical behavior of these compounds using cyclic voltammetry is performed while monitoring the UV absorbance spectra of transient and product species in situ. In search of a low-cost solution-phase detection technique, we compare the spectroelectrochemistry of these compounds in the absence and presence of naturally dissolved oxygen (~2 mM in AcN), where the superoxide radical is co-electrogenerated during explosive analyte reduction. Free superoxide yields an intense UV signal in this medium (λmax = 250 nm) that the explosives attenuate to varying degrees. We deconvolute UV spectral data through time- and potential-resolved analyses coupled with electrochemical data. It is found that superoxide interacts with the explosives through unique, previously unreported ways, likely due to strongly polarized electrostatic potentials across the poly-nitro aliphatic molecules. Reaction mechanisms will be proposed and the findings expand the understanding of high-explosive solution chemistry and offer a route to novel signal transduction for (electro-)chemical sensors for energetic materials.
Figure 1. Spectroelectrochemistry of the control solution, aerated 0.1 M TBAPF6 in acetonitrile. (a) CV (ν = 50 mV s-1) in time and potential domains with the superoxide absorbance at 250 nm plotted for qualitative visualization; (b) time-resolved, full-spectrum UV data recorded during the CV.

Figure 1
Composite Ag/AgCl/KCl Screen-Printed Reference Electrode
Authors: Dawkins Rebecca Claire , Vepsalainen Mikko , Hart Judy Nancy 
Published: May 2020

The drive for automation in multiple industries has generated unmet demand for low-cost, disposable sensors with short response times for routine electrochemical sensing. Glass ion selective electrodes containing a liquid electrolyte have remained the standard for decades, despite their fragile, bulky nature and regular maintenance requirements restricting their suitability for long-term in-situ monitoring. Advances in printing technologies have enabled solid thick film electrodes to emerge as a possible solution to these challenges.
Screen printing can be used to mass-produce units of simple, modifiable, and reproducible sensors using minimal materials, increasing portability and reducing fabrication costs. Traditional glass electrode materials are not suitable for printed fabrication, so new materials and designs are required to deliver reliable and robust printed sensors for a variety of industries. While electrochemical sensors can be used to monitor key aqueous environmental indicators, including pH, heavy metals, and oxidation-reduction potential, they often require a stable reference electrode to gain meaningful measurements. Many previous printed electrochemical sensors have relied on a pseudo-reference electrode containing no stabilising electrolyte, however any resultant potential variation can affect measurement accuracy in unknown solutions.
In this study, a new screen-printed "true" reference electrode was developed based on Ag/AgCl and a solid composite KCl electrolyte. The electrode lifetime was tested in a 0.1 M K2SO4 solution, and open circuit potential (OCP) stability was tested in H2SO4, KOH, alkali cations (Li+, K+, Na+), halogen anions (F-, Cl-, Br-, I-), KMnO4, H2O2, ascorbic acid, KCl, and standard pH buffers (pH 4, 7, 10). The initial stabilisation and water permeation was monitored via electrochemical impedance spectroscopy (EIS).
The observed electrode lifetime in 0.1 M K2SO4 was up to 39 days, with less than 5 mV deviation from the theoretical value (-45 mV vs SCE) and a shelf life of over 1 year. According to the EIS and OCP data, the electrode typically stabilised within 2 hours. In the stability tests, the electrode potential did not deviate more than 10 mV from the theoretical value in the presence of KOH, alkali cations, halogen anions, ascorbic acid, KCl, and standard pH buffers. The electrode was also stable in H2O2 at concentrations up to 0.1 M. On average, the electrode potential was 12 mV below the theoretical value in 10% H2SO4 and was significantly below the theoretical value in 0.1 M KMnO4.
The results of this study suggest that this screen-printed reference electrode is suitable for use in electroanalytical systems in most tested chemical environments. The relatively long lifetime and stability of the electrode allows it to be used in a variety of applications, including environmental monitoring, laboratory measurements, and industrial process monitoring, as part of a printed sensor system.
Surface X-Ray Diffraction Studies of Single Crystal Electrochemistry
Authors: Lucas Christopher A. , Grunder Yvonne 
Published: May 2020

The atomic structure on the metal side of the electrochemical interface depends on the applied electric potential and the nature of the adsorbing species in the electrolyte solution. In this poster we will present some recent results probing surface stress and surface relaxation effects in single crystal metal electrodes that are driven by potential changes. The principal method for probing changes in the atomic structure at the interface is surface x-ray diffraction employing the use of high intensity synchrotron radiation [1]. Measurements on Pt(hkl), Au(hkl) and Ag(hkl) electrodes enable a comprehensive study of the phenomena of surface reconstruction and surface relaxation. The measurements also give insight into the potential-dependent layering in the liquid side of the interface. Both the potential and the structure in the electrolyte layers at the interface alter the metal electronic structure so that the surface in the electrochemical environment is strongly modified from the ultra-high vacuum (UHV) counterpart. A methodology for linking experimental and theoretical approaches for a fundamental understanding of electrochemical reactions will be presented.
[1] Y. Gründer and C. A. Lucas, NanoEnergy, 29, 378-393 (2016).
Electrochemical Semiconductor Analysis By Square Wave Voltammetry
Authors: Miljkovic Bojan , Ruda Harry E 
Published: May 2020

Studies in the past 20 years have utilized cyclic voltammetry (CV) for determining various electronic properties (e.g. density of states, electron carrier concentrations, trap state capacitances) of semiconducting titanium oxide films in photoelectrocatalytic systems such as dye-sensitized solar cells [1-4]. Though primarily used for redox sensing, this work presents square wave voltammetry (SWV) as an alternative to determining said properties. As an electrochemical characterization technique, SWV can provide significantly less background current and greater sensitivity than CV [5]. This is beneficial for the accurate measurement and calculation of electronic properties from electrochemical semiconductor current-voltage data. By varying the applied frequency as well as step and/or pulse sizes of the square wave, one can probe electronic processes of various time scales, in contrast to CV which only allows control of the potential scanning rate across the same potential window [5, 6]. This work presents a comparative study of electronic properties as determined by SWV versus CV for various semiconducting electrodes such as silicon, germanium, titanium oxide, and doped diamond films. This technique was also extended to semiconductor heterostructures - such as noble metal-decorated titanium oxide - for observation of intraband gap states and their contribution to the overall electronic properties of the electrode as determined by SWV.
[1] Liu, B. et. al., “Intrinsic intermediate gape states of TiO2 materials and their roles in charge carrier kinetics”, J. Photochem. and Photobio. C: Photochem. Rev., 39 (2019) 1-57
[2] Zare, M., Mortezaali, A., and Shafiekhani, A., “Photoelectrochemical determination of shallow and deep trap states of platinum-decorated TiO2 nanotube arrays for photocatalytic applications”, J. Phys. Chem. C, 120 (2016) 9017-9027
[3] Fabregat-Santiago, F. et al., “High carrier density and capacitance in TiO2 nanotube arrays induced by electrochemical doping”, J. Am. Chem. Soc., 130 (2008), 11312-11316
[4] Abayev, I. et al., “Properties of the electronic density of states in TiO2 nanoparticles surrounded with aqueous electrolyte”, J. Solid State Electrochem, 11 (2007) 647-653
[5] Mirceski, V. et al., ”Square-wave voltammetry: A review on the recent progress”, Electroanalysis, 25 (2013) 2411-2422
[6] Bard, A. J. and Faulkner, L. R., Electrochemical Methods: Fundamentals and Applications, 2nd ed. Hoboken, NJ: John Wiley & Sons, Inc., 2001.
Pt/Ga Microelectrode Localized Lithium Detection in Li-Ion Battery Electrolytes
Authors: Hatami Mojgan , sazzad Hossain Md , Schougaard Steen Brian 
Published: May 2020

Local Li+ ion detection in the Lithium Ion Batteries (LIBs) is important as lithium ions are exchanging between cathode and anode material via the electrolyte during battery operation. Therefore, the goal here is to develop a technique to detect lithium ions transport within the electrolyte filled porous network of the cathode.
Scanning electrochemical microscopy (SECM) was chosen for Li+ detection in this study as a powerful tool for recoding the in situ electrochemical behavior of this chemical species.1,2 A Pt/Ga microelectrode was used as a probe for SECM. After preparing a cone shape Pt/Ga microelectrode and using anodic stripping voltammetry (ASV) or square wave voltammetry (SWV), a linear current response from 0.3-5 mM Li+ concentrations was obtained. The limit of detection was determined to 77 µM. These result firmly established Pt/Ga microelectrode as a reliable probe for determining the diffusion of Li+ ion from different locations of the LIB solid materials.

References:

(1) Polcari, D.; Dauphin-Ducharme, P.; Mauzeroll, J. Chemical reviews
2016, 116, 13234-13278.
(2) Barton, Z. J.; Rodríguez-López, J. n. Analytical chemistry
2014, 86, 10660-10667.

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Autonomous Electrolyte Discovery for Batteries with Experimentally Informed Bayesian Optimization
Authors: Dave Adarsh , Mitchell Jared , Kandasamy Kirthevasan , Burke Sven , Paria Biswajit , Poczos Barnabas , Whitacre Jay F , Viswanathan Venkat 
Published: May 2020

An autonomous battery electrolyte experimental platform capable of mixing multi-component electrolyte systems and characterizing the transport and electrochemical properties in a high-throughput manner is disclosed. A Bayesian optimization software package found novel electrolyte compositions through optimization of the high-dimensional electrolyte design space over key design objectives like electrochemical stability and conductivity.
Electrolyte optimization is difficult because 1) electrolyte evaluation is expensive and takes time, and 2) the space of possible electrolytes is expansive, formed by many possible choices for solvents (often in ternary blends), salts (often in binary mixtures), and trace additives. Bayesian optimization methods are well suited for the optimization of high-dimensional functions with costly evaluations, often producing an efficient design-of-experiments to converge on multi-objective optimal formulations in few experiments. To expedite the optimization over the expansive design space, theoretical predictions of electrolyte properties via the Advanced Electrolyte Model were utilized as “priors” in the statistical model.
Implementation of the novel experimental platform was carried out by two novel test stands developed to automate the mixing and characterization of electrolytes: Otto (for aqueous systems) and Clio (for aprotic/organic systems). The test stands characterized the ionic conductivity and electrochemical stability of electrolyte systems, featuring a four-electrode conductivity probe, pH meter, and a flow-through three-electrode cell and potentiostat. Clio also integrated electrochemically active electrodes for optimization of electrolyte/electrode systems. The active electrode systems used were common functional ceramic metal oxides.
A software orchestration and data layer linked the test-stands to human experimenters and machine-learning packages through a web-services architecture; all experiment data and meta-data is saved in a database. Additional out-of-the-loop characterization was conducted on cathodic systems to validate composition, structure, and oxidation state.
The aqueous design space consisted of aqueous blends of lithium and sodium salts, including nitrates, sulfates, and other commonly-used battery salts. High-concentration aqueous electrolyte candidates were discovered by optimizing of electrochemical voltage stability and conductivity, including low-cost, high-performing alternatives to known but costly aqueous electrolytes (e.g. LiTFSI). Clio’s design space includes blends of both aprotic organic solvents and solutes in additional to various compositions of electrochemically active electrodes. The test-stands are demonstrated to be significantly faster than common human experimentation techniques, converging on novel, optimized electrolyte mixtures in mere hours or days of experimentation.
Spectroscopic Analysis of LixMnyFe1-YPO4 Cathodes Materials to Revel the Phase Transition Mechanism.
Authors: Savignac Laurence , Griffin John M. , Schougaard Steen Brian 
Published: May 2020

Olivine-type mixed-metal phosphate cathodes have demonstrated their ability to efficiently store energy in a wide range of applications. Moreover, ultrafast charging rates (seconds order) are observed for the LiFePO4 system. Nonetheless, charge storage proceeds via a phase transition mechanisms where fully charged or discharged particles act as electronic insulators. Considering olivine as a model structure with its outstanding stability, a higher energy density material is achieved by the incorporation of high operating potential transition metals. The challenge here is to understand the exact Li+ transport mechanism engendered by the modified crystalline structure, as it impacts on the dynamics of de/lithiation process.
For the purpose of identifying the encountered phase transition mechanism is impacted by the nature of the redox active sites, a range of LixMnyFe1-yPO4 (0 ≤ y ≤ 0.9) has been delithiated by a chemical route resulting in materials at various state of charge. Powder X-ray diffraction (PXRD) and Rietveld refinement was used to describe the bulk crystalline structure. 6Li nuclear magnetic resonance (MAS NMR) and attenuated total reflectance infrared spectroscopy (ATR-IR) where employed to detect the Li+ and PO4 local environments, respectively. The information obtained by spectroscopic characterizations, e.g. local organization of transitions metals and their oxidations state, phosphate backbone distortion and presence of defects, provide an exhaustive image of the phases changes, including the crucially the Li+ transport mechanism in high energy density cathodes.

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Suppressing Electrochemical Instabilities of Li Metal Using Ionomer-Based Interfaces
Authors: Huang Zhuojun 
Published: May 2020

A fundamental challenge shared across many energy storage devices, is the complexity of electrochemistry at the electrode-electrolyte interfaces that impacts the faradaic efficiency, operational rate capability and lifetime. Specifically, in energy-dense lithium metal batteries, the charging process results in morphological heterogeneity of the metal anode, leading to battery failure by short-circuit or capacity fade. Perhaps, a facile way of addressing these challenges is designing a polymer thin-film at the electrode-electrolyte interface. We envision that an ideal interface should be based on several design principles including: presence of Li+ ion conduction pathway; chemically inert, mechanically robust, adaptive to volume changes and solution-processable for large scale thin-film casting.
Here, we use free-radical polymerization technique to synthesize novel stimuli-responsive polymers which exhibit the aforementioned characteristics. Unlike, previous works where the electrode coating acts as a pure physical barrier, the designer polymers in this work possess multifunctional characteristics to suppress different electrochemical instabilities. Because of the viscoelastic and electroactive nature of the polymers, they respond to any morphological changes of the electrodes during electrodeposition, giving rise to an electrochemical shielding mechanism that modulates lithium ion migration pathway and prevents surface roughening.
This work takes advantage of contemporary characterizations techniques like NMR, voltammetry and rheology to mechanistically understand the role of polymer dynamics and ion content on the electrodeposition morphology. We show that systematic optimization of these parameters can significantly boost the coulombic efficiency of the battery. Remarkably, we found that these polymer coatings can enhance the lifetime of conventional high-voltage lithium metal battery by at least two-times.