Characterization Of Electrode Surface Research Articles

Fabrication of DNA/2-thiobarbituric acid-osmium tetroxide/pencil graphite electrode and its application for the electrochemical determination of trace amounts of efavirenz

Efavirenz (EFA) is an antiviral drug that reduces the progression of HIV infection by reducing the virus's proliferation in the blood. This study used a pencil graphite electrode modified with deoxyribonucleic acid/2-thiobarbituric acid-osmium tetroxide (DNA/TBA-OsO4/PGE) to measure traces of the drug. The electrode surface was modified in two stages by the electrodeposition of thiobarbituric acid-osmium tetroxide and DNA, respectively. Electrode surface characterization was revealed by high-resolution scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Analytical figures of merit, such as the linear range over the concentration range of 1 × 10−12 to 1 × 10−5 M and the detection limit of 1.4 × 10−13 M, demonstrated that the modified DNA/TBA-OsO4/PGE is superior to the other proposed electrodes for the determination of EFA. Additionally, the modified electrode was used to measure EFA in blood, urine and water samples.

A Carboranyl Electrolyte Enabling Highly Reversible Sodium Metal Anodes via a “Fluorine‐Free” SEI

AbstractRealization of practical sodium metal batteries (SMBs) is hindered due to lack of compatible electrolyte components, dendrite propagation, and poor understanding of anodic interphasial chemistries. Chemically robust liquid electrolytes that facilitate both favorable sodium metal deposition and a stable solid‐electrolyte interphase (SEI) are ideal to enable sodium metal and anode‐free cells. Herein we present advanced characterization of a novel fluorine‐free electrolyte utilizing the [HCB11H11]1− anion. Symmetrical Na cells operated with this electrolyte exhibit a remarkably low overpotential of 0.032 V at a current density of 2.0 mA cm−2 and a high coulombic efficiency of 99.5 % in half‐cell configurations. Surface characterization of electrodes post‐operation reveals the absence of dendritic sodium nucleation and a surprisingly stable fluorine‐free SEI. Furthermore, weak ion‐pairing is identified as key towards the successful development of fluorine‐free sodium electrolytes.

Electrochemical immunosensor for the detection of colistin in chicken liver.

An innovative amperometric immunosensor has been developed to detect antibiotic colistin from the chicken liver. Colistin is a antibacterial peptide that has been barred for human consumption, but it is being commonly used as a veterinary drug, and as a feed additive for livestock. In the present work, an immunosensor was developed by immobilizing an anti-colistin Ab onto the CNF/AuNPs surface of the screen-printed electrode. The sensor records electrochemical response in the chicken liver spiked with colistin with CV. Additionally, the characterization of electrode surface was done with FE-SEM, FTIR, and EIS at each step of fabrication. The lower LOD was 0.89μgKg-1, with a R 2 of 0.901 using CV. Further validation of the immunosensor was conducted using commercial chicken liver samples, by comparing the results to those obtained using traditional methods. The fabricated immunosensor showed high specificity towards colistin, which remained stable for 6months but with a 13% loss in the initial CV current.

(Digital Presentation) Enhanced Electrochemical Phosphate Recovery from Wastewater: Implications of Pulsating Anode Potential

Electrochemical recovery of phosphorus (P) as struvite (or magnesium ammonium phosphate hexahydrate, MgNH4PO4.6H2O) fertilizer using a sacrificial pure magnesium (Mg) anode is considered a sustainable strategy to deal with the limited availability of rock phosphate. However, the formation of an electrically passive film of magnesium hydroxide (Mg(OH)2) and/or struvite on the surface of Mg upon immediate immersion in aqueous phosphate solution limits the release of divalent Mg ions and decreases struvite precipitation. The present work highlights struvite recovery by an electrochemical method upon application of a dynamic voltage with a sinusoidal waveform. Our results demonstrate that a dynamic potential, when compared to a constant potential, can enhance the rupture of the passivating film, and facilitate the release of Mg2+ from the metal thereby overcoming the problems related to electrical passivation.Aqueous solutions of ammonium dihydrogen phosphate (NH4H2PO4, 10 mM) at neutral pH were used as test solutions. Mg2+ release was notably increased by ~48% relative to constant voltage applications, which subsequently led to ~20% higher phosphate recovery. Characterization studies including X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated the presence of struvite in the recovered precipitate. Surface characterization of electrodes using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) also confirms a higher extent of passivating film breakdown in the presence of dynamic voltage.

Electrochemical sensors based on sewage sludge–derived biochar for the analysis of anthocyanins in berry fruits

The reutilization of waste and the reduction of the general environmental impact of every production are fundamental goals that must be achieved in the framework of a circular economy. Recycled carbon-rich materials may represent a promising alternative to other less-sustainable carbonaceous materials used in the production of electrochemical sensing platforms. Herein, we propose an innovative carbon paste electrode (CPE) composed of biochar derived from biological sludge obtained from municipal and industrial wastewater treatment plants. The physicochemical properties of the biochar after a chemical treatment with an acidic solution obtained from industrial by-products were investigated. The electrode surface characterization was carried out by analyzing common redox probes and multiple phenols bearing varying numbers of –OH and –OCH3 groups in their structure. Furthermore, the CPE was also tested on the evaluation of the phenolic fingerprints of Vaccinium myrtillus, Vaccinium uliginosum subsp. gaultherioides, and Fragaria × ananassa. Standard anthocyanin mixtures and extracts of the aforementioned fruits were analyzed to provide a phenolic characterization of real samples. The obtained results show that the sewage sludge–derived biochar can be a promising material for the development of electroanalytical sensors.Graphical abstract

The potential of scanning electrochemical probe microscopy and scanning droplet cells in battery research

AbstractSpatially resolved characterization of electrode surfaces or electrode–electrolyte interfaces is of fundamental interest in battery research to unravel the complex underlying physicochemical processes. Scanning probe microscopy (SPM) techniques and derived methods have recently gained importance in in situ or operando studies of battery electrodes. This minireview provides an overview on well‐established and advanced SPM methods such as scanning electrochemical cell microscopy (SECCM) and hybrid atomic force microscopy–scanning electrochemical microscopy (AFM‐SECM) and their future potential for in situ/operando studies providing correlated structure/reactivity information. Although, most studies so far are focusing on lithium (Li)‐ion batteries, the potential for post‐Li battery chemistries is clearly evident. Future approaches for rapid performance assessment using scanning droplet cell electrochemistry in combination with advanced scanning probe microscopy are proposed and contrasted with the emerging challenges in the characterization of novel battery chemistries, as SPM methods have not yet been much used in this research area.

Experimental investigation on the effect of surface characterization of electrodes on the gas bubble dynamics in electrolyte flow and performance of FLA batteries by using PIV

Generation of oxygen and hydrogen bubbles at vicinity of the electrodes FLA battery at SOC 60%. In the flooded lead_acid batteries (FLAB), gas bubbles are initially formed on the surface of the electrodes, which are produced by electrochemical reactions, and then released into the electrolyte. In the present investigation, the effect of surface characterization of electrodes of FLAB on the gas bubble dynamic parameters in the electrolyte flow at different charging/discharging rates (C-rates) are studied utilizing particle image velocimetry (PIV) method. The results show that the capacity of FLAB have a linear behavior due to changes in each of the two parameters of the surface characterization of electrodes and the C-rate. At all State of charges (SOCs) of FLAB cells in different tests, increasing average roughness ( Ra ) and average wavelength of the roughness ( λa ) in the electrode surfaces, results in an increase in average bubble diameter and bubble rising velocity. Nevertheless, a sharp decrease in the void fraction of bubbles within the electrolyte was observed due to the increment in λa and Ra . Also, the effect of the rising movement of gas bubbles within the electrolyte on the average electrolyte velocity pattern in the gap between the electrodes by changing the surface characterization of electrodes are investigated in detail.

Cu-TiO2 doped Ti thin-layer photoelectrode for visible-light induced photoelectrocatalytic activities: degradation of methylene orange

Cu-TiO2 doped Ti thin layer was prepared by anodizing and electrodeposition. Characterization electrode using Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX) and activity test using Linear Sweep Voltammetry (LSV) under UV and visible light to degrade methylene orange. The result of electrode surface characterization using EDX showed that the Cu peak at 0.992 keV indicated the precious metal Cu on the TiO2/Ti electrode. The activity test of Cu-TiO2/Ti electrode by Linear Sweep Voltammetry (LSV) showed the electrode activities on the visible light. The TiO2/Ti electrode has activities on the UV light. Degradation test Cu-TiO2/Ti electrode by photoelectrocatalyst against methylene orange showed the percentage of degradation produced was 92.88%.

A Label-free Electrochemical Immunosensor for Highly Sensitive Detection of TNF α, Based on Star Polymer-modified disposable ITO Electrode

Background: Biomarkers are very important disease-related biomolecules which should be analyzed sensitive and selective in related physiological fluids or tissues. Tumor necrosis factor-α is a type of cytokine which plays vitlly important roles in different methabolic pathways such as cell death, survival, differentiation, proliferation and migration, and infectious and inflammatory diseases including rheumatoid arthritis, diabetes. Objective: In this study, it was aimed to develop a reliable tool based on star-shaped poly(glycidyl methacrylate) polymer coated disposable indium tin oxide electrode for determination of Tumor necrosis factor-α, an important disease biomarker. Methods: Star shaped polymer was used as an interface material for anti- Tumor necrosis factor α antibodies immobilization. The antibodies were immobilized covalently onto polymer coated indium tin oxide electrode. Electrochemical impedance spectroscopy and cyclic voltammetry techniques were used for all electrochemical measurements. Results: The suggested immunosensor exhibited a linear range between 0.02 and 4 pg/mL Tumor necrosis factor-α, and the detection limit was found as 6 fg/mL. Scanning electron microscopy and atomic force microscopy were used for electrode surface characterization. In addition, the suggested immunosensor was used for Tumor necrosis factor-α sensing in human serum samples. The results displayed recoveries between 97.07 and 100.19%. Moreover, this immunosensor had a simple fabrication procedure and a long storage-stability. Conclusion: A new biosensor based on a Star shaped polymer for the ultra sensitive determination of a biomarker Tumor necrosis factor-α was developed. The biosensor presented excellent repeatability and reproducubility, and also wide calibration range for Tumor necrosis factor- α.

The Oxygen Reduction Reaction in Ca2+ -Containing DMSO: Reaction Mechanism, Electrode Surface Characterization, and Redox Mediation*.

In this study the fundamental understanding of the underlying reactions of a possible Ca−O2 battery using a DMSO‐based electrolyte was strengthened. Employing the rotating ring disc electrode, a transition from a mixed process of O2 − and O2 2− formation to an exclusive O2 − formation at gold electrodes is observed. It is shown that in this system Ca‐superoxide and Ca‐peroxide are formed as soluble species. However, there is a strongly adsorbed layer of products of the oxygen reduction reaction (ORR) s on the electrode surface, which is blocking the electrode. Surprisingly the blockade is only a partial blockade for the formation of peroxide while the formation of superoxide is maintained. During an anodic sweep, the ORR product layer is stripped from the electrode surface. With X‐ray photoelectron spectroscopy (XPS) the deposited ORR products were shown to be Ca(O2)2, CaO2, and CaO as well as side‐reaction products such as CO3 2− and other oxygen‐containing carbon species. It is shown that the strongly attached layer on the electrocatalyst, that was partially blocking the electrode, could be adsorbed CaO. The disproportionation reaction of O2 − in presence of Ca2+ was demonstrated via mass spectrometry. Finally, the ORR mediated by 2,5‐di‐tert‐1,4‐benzoquinone (DBBQ) was investigated by differential electrochemical mass spectrometry (DEMS) and XPS. Similar products as without DBBQ are deposited on the electrode surface. The analysis of the DEMS experiments shows that DBBQ− reduces O2 to O2 − and O2 2−, whereas in the presence of DBBQ2− O2 2− is formed. The mechanism of the ORR with and without DBBQ is discussed.

The Influence of Solution pH on the Kinetics of Resorcinol Electrooxidation (Degradation) on Polycrystalline Platinum.

Electrochemical oxidation of resorcinol on a polycrystalline platinum electrode was investigated in five different solutions, namely 0.5 and 0.1 M H2SO4, 0.5 M Na2SO4, 0.5 and 0.1 M NaOH. The rates of electrochemical degradation of resorcinol were determined based on the obtained reaction parameters, such as resistance, capacitance and current-density. The electrochemical analyses (cyclic voltammetry and a.c. impedance spectroscopy) were carried-out by means of a three-compartment, Pyrex glass cell. These results showed that the electrochemical oxidation of resorcinol is strongly pH-dependent. In addition, the energy dispersive X-ray (EDX) spectroscopy technique was employed for Pt electrode surface characterization. Additionally, the quantitative determination of resorcinol removal was performed by means of instrumental high-performance liquid chromatography/mass spectrometry (HPLC/MS) methodology.

Nafion-Protected Sputtered-Bismuth Screen-Printed Electrode for On-site Voltammetric Measurements of Cd(II) and Pb(II) in Natural Water Samples.

In this work, we explore the protection with Nafion of commercial sputtered-bismuth screen-printed electrodes (BiSPSPEs), to improve its ability for on-site determination of Cd(II) and Pb(II) ions in ambient water samples. The modified screen-printed platform was coupled with a miniaturized cell, in combination with a battery-operated stirring system and a portable potentiostat operated by a laptop for decentralized electrochemical measurements using Square-Wave Anodic Stripping Voltammetry (SWASV). We also describe a detailed electrode surface characterization by microscopy and surface analysis techniques, before and after the modification with Nafion, to get insight about modification effect on signal size and stability. Optimization of the chemical composition of the medium including the optimization of pH, and instrumental parameters, resulted in a method with detection limits in the low ng/mL range (3.62 and 3.83 ng·mL−1 for Cd and Pb respectively). Our results show an improvement of the sensitivity and stability for Nafion-protected BiSPSPEs in pH = 4.4 medium, and similar or lower detection limits than comparable methods on commercial BiSPSPEs. The values obtained for Pb(II) and Cd(II) in natural water samples agreed well with those obtained by the much more costly Inductively Coupled Plasma Mass Spectrometry, ICP-MS, technique as a reference method (recoveries from 75% to 111%).

Conducting Polymer/Ionic Liquid Composite Modified Carbon Paste Electrode for the Determination of Carbaryl in Real Samples

AbstractA new method has been described for carbaryl determination using a simple electrochemical sensor. The unique properties of poly‐pPhenylenediamine and ionic liquid were exploited to fabricate carbon paste electrode modified with composite based on conducting polymer/ionic liquid. Electrode surface characterization was performed by electrochemical methods (cyclic voltammetry and electrochemical impedance spectroscopy) and by scanning electron microscopy. Differential pulse voltammetry was employed for the detection of carbaryl in acetate buffer solution. Different parameters affecting the carbaryl response were optimized such as ionic liquid amounts, cycle number of polymerization and monomer concentration, pH, and accumulation time. Under the optimum experimental conditions, a linear response was obtained between 0.5 and 200 μmol/L, with detection limit of 0.09 μmol/L. The developed sensor offered satisfactory results for carbaryl detection in spring water and fruit samples.

Lithiation Effect of the Poly(Acrylic Acid) Binders on the Silicon Anode of Lithium-Ion Batteries

The exploration for the next generation of anode materials in the lithium-ion batteries is a vital subject in the past few years due to the huge demand of high capacity batteries. Silicon (Si) stands out as a promising anode material due to its high theoretical specific capacity (4200 mAh/g), enviroment friendliness and low costs. However, Si nanoparticles (NPs) experience severe volume changes up to 300 % during the lithiation/delithiation process, which leads to dramatic particle degradation and thus capacity loss. Novel polymeric binders with enhanced mechanical properties have been identified as one effective approach to alleviate this issue, and some examples include carboxymethyl cellulose (CMC), alginate, and poly(acrylic acid) (PAA), etc. By using those binders, cell performance has been greatly improved as compared to the conventional polyvinylidene fluoride (PVDF) binder. Among those candidates, PAA outperforms others possibly due to its superior mechanical properties. In this report we have attempted to investigate the lithiation effect of the PAA binders. Lithiating PAA binders could benefit the electrode laminate processing as well as cycling performance. A commercially available PAA sample with a characterized Mn of 147 kDa was used in this study. By titrating with LiOH solution, we controlled the pH of 10 wt% PAA solutions as well as the lithiation ratio (Table 1). Those binder solutions were used to fabricate silicon/ graphite composite electrodes that composed of 10 % PAA, 73 % Hitachi MagE, 15 % Si NPs (NanoAmour, 70-130 nm), and 2 % Timcal C45. Half-cell cycling results (Figure 1) indicated that different lithiation of PAA binders has dramatic impact on their corresponding cycling performance. Lower lithiation tends to afford higher initial specific capacities and better capacity retentions. Actually, the best performer is PAA binder with no lithiation at all. This result is a little contradicting to previous study but we reason that our lithiation agent, LiOH, may have side reasons with silicon particles, as evidenced by the dramatic decrease of the silicon capacity. Full cell cycling as well as further characterization of electrode surface is ongoing. Table 1. The calculated mol% of LiOH (to AA monomer) and the resulting pH values of the final PAA solutions. LiOH % 0 25 50 75 85 90 91 92.5 95 100 pH 2.08 4.22 4.84 5.49 5.97 6.97 10.03 11.96 12.28 12.59 Figure 1. Specific discharge capacity and Coulombic efficiency of PAA binders with different pH values. Figure 1

Enantioselective analysis of Moxifloxacin hydrochloride enantiomers with graphene-β-Cyclodextrin-nanocomposite modified carbon paste electrode using adsorptive stripping differential pulse Voltammetry

Enantioselective analysis of Moxifloxacin hydrochloride (MOX) enantiomers was investigated on carbon paste electrode (CPE) modified with chiral selector β-Cyclodextrin and graphene nanosheets (GNS) employing adsorptive stripping differential pulse voltammetric (AdSDPV) technique. Electrochemical chiral discrimination was obtained due to β-Cyclodextrin, which has 35 chiral centres as a binding site resulting in very tight fit inclusion complex based on host-guest interactions. Enantioselectivity of present electrode system of graphene nanosheets and β-cyclodextrin modified carbon paste electrode (GNS-β-CD-CPE) gives difference in anodic oxidation peak potential of enantiomers S,S-MOX and R,R-MOX at 1.039V and 0.917V in B.R buffer solution in pH 7 confirming successful enantiomer detection respectively. Various techniques such as X-Ray diffraction (XRD), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and Fourier transform infra red spectroscopy (FT-IR) were employed for characterization of electrode surface. The electrocatalytic response of MOX at GNS-β-CD-CPE was measured using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Electrical conductivity of modified electrode was investigated by electrochemical impedance spectroscopy (EIS) which indicates its good conductivity over plain CPE. The proposed enantioselective electrochemical sensor was highly efficient and capable of sensing optically active isomers of MOX which is the S,S-enantiomer from its potential chiral antipode R,R-MOX enantiomer with large difference of 122mV shift in peak potential which suggests great stereoselectivity is achieved due to chiral environment provided by chiral selector β-Cyclodextrin. Determination of percentage enantiomeric composition of S,S-MOX in racemic mixture extend future applications of chiral electroanalytical system of β-CD. In the present work, it is for the first time enantiomeric electrochemical recognition of multi-chiral drug with two chiral centres has been done voltammetrically.

Utilization of Hard X-Ray Photoelectron Spectroscopy for Silicon-Based Negative Electrodes Buried within Solid Electrolyte Interphase

Silicon is one of the alternative materials for currently used negative electrodes in Li-ion batteries because of its high lithium insertion capability. However, volume expansion of silicon-based active materials accompanied with the lithium insertion is a severe problem towards their practical application since this volume expansion can destroy both the silicon-based material itself and electrical connection composed of binders, current collectors and the silicon-based materials. Hence, understanding of the lithium insertion is essential to design the silicon-based negative electrode with a high tolerance to the volume expansion. However, these negative electrodes are buried with a thin film, so-called, a solid electrolyte interphase (SEI), which often prohibits the characterization of electrode surfaces. X-ray photoelectron spectroscopy (XPS) is a surface-sensitive technique which can analyze the composition and oxidation states of elements within the sample surfaces, and often combined together with destructive ion-sputtering methods to obtain their depth profile. XPS utilizing hard x-rays, so-called HAXPES (Hard X-ray Photoelectron Spectroscopy), can be a complementary non-destructive technique to analyze a deeper region from the surface. Recently, we constructed an in-house HAXPES equipped with a Cr Kα (5415 eV) source for electrode materials buried within the SEI. Here, we compared “destructive” Ar ion sputtering-XPS and “non-destructive” HAXPES to characterize the depth profile of the SEI-covered Si(111) negative electrodes with and without lithium insertion.

Interfacial Studies of the SEI Layer on a Tin Electrode

Development of new innovative experimental approaches and enabling methodologies to understand the function and mechanism of operation of materials, electrodes and electrochemical interfaces in electrical energy storage systems is critical for clean and/or renewable energy technologies. A better understanding of the underlying principles that govern these phenomena is inextricably linked with successful implementation of high energy density materials.Several analytical techniques have been implemented for the physico-chemical characterization of the materials, interfaces and interphases. In many cases limitations in studying the real system are imposed by ex situ methods that require excitation or detection of electrons or ions in vacuum environment and/or they suffer from inadequate sensitivity, selectivity and specificity in the in situ environment. The advent of near-field optical methods during the past decades has led to the development of new advanced techniques for chemical analysis. This presentation provides a brief overview of novel in and ex situexperimental approaches aimed at probing battery materials and electrodes in electrical storage systems at an atom, molecular or nanoparticulate level.A strong understanding of the solid electrolyte interphase (SEI) (1,2) layer in lithium-ion batteries is necessary for further development of the technology, leading the path to application of high energy density intermetallic anodes However, the identification of chemical compounds in this surface layer, as well as their spatial distribution, has been limited by diffraction to the 5-10 μm wavelength scale available to traditional Fourier Transform Infrared spectroscopy (FTIR). This study demonstrates subwavelength imaging of the SEI using infrared (IR) near-field scanning optical microscopy (NSOM). NSOM (3) is a technique based on light confinement at the apex of an atomic force microscope (AFM) probe. The tight optical focusing combined with the placement of the probe within small fractions of a wavelength allow resolution well below the classical diffraction limit, while simultaneously obtaining topographic information about the sample surface and the present SEI. Additionally, this microscope is highly surface-sensitive, allowing selective optical imaging of the interfacial layers. The NSOM used here is configured as part of a pseudo-heterodyne interferometer, which allows high signal-to-noise ratio as well as collection of the optical phase.The observed significant difference of Sn reactivity toward the electrolyte as a function of Sn surface crystalline orientation suggests radically different reaction paths, reduction products, and properties of the surface film. These results were supported by reactivity of polycrystalline tin that was falling in between the two single crystal surfaces. Our most recent measurements however shed new light on these results. We have identified that the native oxide layer present on tin exposed to air, and appreciable oxygen solubility in Sn have a major contribution to the electrochemical response of the Sn electrode. The presented experimental methodologies exploit the micro and nano-manipulation techniques and Sn single crystal model electrodes to provide sufficient sample definition suitable for advanced X-ray, far- and near-field Raman, FTIR and electrochemical characterization techniques. Examples of detailed in situmolecular characterization of electrode surface and bulk processes at the nano-level scale limit will be discussed. These include elemental and molecular depth profiling at nanometer-scale depth resolution of a solid electrolyte interface (SEI) layer formed on Sn polycrystalline and monocrystral model electrodes in an organic carbonate-based electrolyte.AcknowledgementPart of this work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy, under contract no. DE-AC02-05CH11231. It has also been supported in part by the Northeastern Center for Chemical Energy Storage, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award number DESC0001294. This work was also supported in part by the Chemical Science Division, Office of Basic Energy Sciences, Office of Nuclear Nonproliferation, and the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Far- and Near-Field Spectroscopy and Imaging of the SEI Layer on a Tin Electrode.

Development of new innovative experimental approaches and enabling methodologies to understand the function and mechanism of operation of materials, electrodes and electrochemical interfaces in electrical energy storage systems is critical for clean and/or renewable energy technologies. A better understanding of the underlying principles that govern these phenomena is inextricably linked with successful implementation of high energy density materials.Several analytical techniques have been implemented for the physico-chemical characterization of the materials, interfaces and interphases. In many cases limitations in studying the real system are imposed by ex situ methods that require excitation or detection of electrons or ions in vacuum environment and/or they suffer from inadequate sensitivity, selectivity and specificity in the in situenvironment.The advent of near-field optical methods during the past decades has led to the development of new advanced techniques for chemical analysis. This presentation provides a brief overview of novel in and ex situexperimental approaches aimed at probing battery materials and electrodes in electrical storage systems at an atom, molecular or nanoparticulate level.A strong understanding of the solid electrolyte interphase (SEI) (1,2) layer in lithium-ion batteries is necessary for further development of the technology, leading the path to application of high energy density intermetallic anodes However, the identification of chemical compounds in this surface layer, as well as their spatial distribution, has been limited by diffraction to the 5-10 μm wavelength scale available to traditional Fourier Transform Infrared spectroscopy (FTIR). This study demonstrates deeply subwavelength imaging of the SEI using infrared (IR) near-field scanning optical microscopy (NSOM). NSOM (3) is a technique based on light confinement at the apex of an atomic force microscope (AFM) probe. The tight optical focusing combined with the placement of the probe within small fractions of a wavelength allow resolution well below the classical diffraction limit, while simultaneously obtaining topographic information about the sample surface and the present SEI. Additionally, this microscope is highly surface-sensitive, allowing selective optical imaging of the interfacial layers. The NSOM used here is configured as part of a pseudo-heterodyne interferometer, which allows high signal-to-noise ratio as well as collection of the optical phase.The presented methodologies exploit the micro and nano-manipulation techniques and Sn single crystal model electrodes to provide sufficient sample definition suitable for advanced far- and near-field Raman, FTIR and electrochemical characterization techniques. Examples of detailed in situmolecular characterization of electrode surface and bulk processes at the nano-level scale exceeding the diffraction limit will be discussed. These include elemental and molecular depth profiling at nanometer-scale depth resolution of a solid electrolyte interface (SEI) layer formed on Sn polycrystalline and monocrystral model electrodes in an organic carbonate-based electrolyte.AcknowledgementPart of this work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy, under contract no. DE-AC02-05CH11231. It has also been supported in part by the Northeastern Center for Chemical Energy Storage, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award number DESC0001294. This work was also supported in part by the Chemical Science Division, Office of Basic Energy Sciences, Office of Nuclear Nonproliferation, and the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Flame Oxidation of Stainless Steel Felt Enhances Anodic Biofilm Formation and Current Output in Bioelectrochemical Systems

Stainless steel (SS) can be an attractive material to create large electrodes for microbial bioelectrochemical systems (BESs), due to its low cost and high conductivity. However, poor biocompatibility limits its successful application today. Here we report a simple and effective method to make SS electrodes biocompatible by means of flame oxidation. Physicochemical characterization of electrode surface indicated that iron oxide nanoparticles (IONPs) were generated in situ on an SS felt surface by flame oxidation. IONPs-coating dramatically enhanced the biocompatibility of SS felt and consequently resulted in a robust electroactive biofilm formation at its surface in BESs. The maximum current densities reached at IONPs-coated SS felt electrodes were 16.5 times and 4.8 times higher than the untreated SS felts and carbon felts, respectively. Furthermore, the maximum current density achieved with the IONPs-coated SS felt (1.92 mA/cm(2), 27.42 mA/cm(3)) is one of the highest current densities reported thus far. These results demonstrate for the first time that flame oxidized SS felts could be a good alternative to carbon-based electrodes for achieving high current densities in BESs. Most importantly, high conductivity, excellent mechanical strength, strong chemical stability, large specific surface area, and comparatively low cost of flame oxidized SS felts offer exciting opportunities for scaling-up of the anodes for BESs.

Far- and Near-Field Spectroscopy and Imaging of Interfaces and Interphases in Li-Ion Battery Electrodes

Development of new innovative experimental approaches and enabling methodologies to understand the function and mechanism of operation of materials, electrodes and electrochemical interfaces in electrical energy storage systems is critical for clean and/or renewable energy technologies. A better understanding of the underlying principles that govern these phenomena is inextricably linked with successful implementation of high energy density materials.Several analytical techniques have been implemented for the physico-chemical characterization of the materials, interfaces and interphases. In many cases limitations in studying the real system are imposed by ex situ methods that require excitation or detection of electrons or ions in vacuum environment and/or they suffer from inadequate sensitivity, selectivity and specificity in the in situ environment.The advent of femtosecond (fs) lasers and near-field optical methods during the past decades has led to the development of new advanced techniques for chemical analysis. This presentation provides a brief overview of novel in and ex situ experimental approaches aimed at probing battery materials and electrodes in electrical storage systems at an atom, molecular or nanoparticulate level.The presented methodologies exploit the micro and nano-manipulation techniques and single particle model electrodes to provide sufficient sample definition suitable for advanced far- and near-field Raman, FTIR , fluorescence spectral microscopy, pumped laser probes and micro- and nano-electrochemical characterization techniques.Examples of detailed in situ molecular characterization of electrode surface and bulk processes at the nano-level scale exceeding the diffraction limit will be discussed. These include elemental and molecular depth profiling at nanometer-scale depth resolution of a solid electrolyte interface (SEI) layer formed on Sn polycrystalline and monocrystral model electrodes in an organic carbonate-based electrolyte.AcknowledgementPart of this work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy, under contract no. DE-AC02-05CH11231. It has also been supported in part by the Northeastern Center for Chemical Energy Storage, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award number DESC0001294. This work was also supported in part by the Chemical Science Division, Office of Basic Energy Sciences, Office of Nuclear Nonproliferation, and the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.