Thin-layer Electrode Research Articles

An Electrochemical Pipette for the Study of Drug Metabolite.

Electrochemistry offers an effective means of mimicking enzymatic metabolic pathways, particularly the oxidative pathways catalyzed by the cytochrome P450 superfamily. The electrochemical generation and identification of metabolites are time-sensitive, necessitating adjustable cell designs for an accurate mechanistic interpretation. We present a thin-layer electrode (TLE) that addresses the needs of both the analytical and synthetic electrochemical generation of drug metabolites. The TLE's ability to conduct experiments on a minute-to-hour time scale allows for detailed observation of reaction mechanisms for metabolites not easily identified by traditional methods. The utility of the TLE for drug metabolites was benchmarked for electrochemical oxidation of acetaminophen, acebutolol, and 2-acetyl-4-butyramidophenol, known to produce quinone imine metabolites, i.e., NAPQI, upon oxidation. When combined with a microelectrode (μE), the TLE enables probing of the concentration profiles for metabolic oxidation of these drugs. The micromole scale and pipette-type structure of the TLE facilitate comprehensive structural elucidation of intermediates and products using chromatographic and spectroscopic techniques.

An Electrochemical Pipette for Study of the Drug Metabolites

The similarity between electrochemical and biological redox reactions, particularly in the realm of CYP450-catalyzed oxidation, provides the basis for using electrochemistry to simulate drug metabolism and to synthesize complex drug candidates. The tunability of electrochemical reactions, mild reaction conditions, and the avoidance of toxic reagents are the characteristics of electrochemical reactions in mimicking enzymatic drug metabolites. The acquired insights from these techniques can be used to assess the metabolites' potential toxicity and pharmacological properties. These features along with insights from electrochemical drug metabolism enable chemists to accomplish transformations on complex, functionalized molecules with high selectivity and hold great promise for improving the processes used for pharmaceutical synthesis. An instance is exemplified by acetaminophen (APAP), for which adverse side effects have been ascribed to the oxidative generation of a metabolite known as N-acetyl-p-benzoquinone imine (NAPQI). This well-established area showcased impressive examples of the ability of electrochemistry to replicate phase I and II APAP metabolism reactions. Yet, it is often limited to an analytical scale, hampering comprehensive characterization and complete metabolic behavior elucidation. The synthetic scale preparation of metabolites for quantitative analysis and their further studies is a valuable complementary approach to EC-MS techniques.Recently, we designed a thin layer electrode that the electrode can be pulled and pushed, like a pipette inside a glass tube, allowing for the taking in and expelling of the sample into and from the thin layer, respectively.1 The thin layer electrochemical pipette allows rapid electrolysis on a microscale making it suitable for the study of the products or intermediates of drug metabolites. The required time for electrolysis or voltammetric experiments in this TLE is in order of minutes, shorter than traditional electrolysis cells, and longer than many of the electroanalytical techniques. This allows us to detect and investigate the drug metabolites with a minute scale half-life. Herein, we showcase the utilization of microscale electrolysis to investigate drug metabolites, specifically elucidating the oxidation pathways of paracetamol and acebutolol drugs using thin-layer electrolysis (TLE) and cyclic voltammetry (CV). We successfully identified well-defined redox peaks of p-benzoquinone and hydroquinone, which remain undetectable through conventional electrolysis, whether in short or extended durations. Additionally, employing a microelectrode in the TLE facilitates the real-time examination of concentration profiles for both redox-active and inactive components involved in electrosynthesis reactions, allowing us to extract valuable kinetic information. Conducting CV experiments within the framework of (TLE) not only yielded detailed electrochemical insights into the mechanisms but also produced micromole-scale products, which can be fully characterized via chromatographic or spectroscopic methods.1. B.T. Punchihewa, V. Minda, W.G. Gutheil, M. Rafiee, Electrosynthesis and Microanalysis in Thin Layer: An Electrochemical Pipette for Rapid Electrolysis and Mechanistic Study of Electrochemical Reactions. Angew. Chem. Int. Ed. 2023, 62, e202312048.

MAX Phase Ti2AlN for HfO2 Memristors with Ultra‐Low Reset Current Density and Large On/Off Ratio

AbstractA Ti2AlN MAX phase layered thin film electrode and oxygen getter layer for HfO2‐based two‐terminal memristors is presented. The Ti2AlN/HfOx/Ti memristor devices exhibit enhanced resistive switching performance, including an ultra‐low reset current density (< 10−8 MΩ cm2), substantial on‐off ratio (≈ 6000), excellent multi‐level functionality (≈ 9 distinct states), impressive retention (up to 300 °C), and robust endurance (>200 million) as compared to conventional TiN and other alternative materials based memristors. Experimental measurements and modeling suggest that the distinctive combination of low thermal conductivity, high electrical conductivity, and unique ultra‐thin layer‐by‐layer structure of the Ti2AlN MAX phase thin film contribute to this exceptional performance with good reproducibility and stability. The results demonstrate for the first‐time the potential of this innovative sputtered MAX phase material for engineering energy‐efficient, high‐density non‐volatile digital, and analog memory devices aimed toward next‐generation sustainable artificial intelligence.

Modification of Fuel Electrode Microstructure for Protonic Ceramic Cells by the Infiltration of Various Metal Nanoparticles

Proton ceramic cells (PCCs) are promising eco-energy electrochemical energy conversion systems. Proton conducting perovskite oxide electrolytes of PCCs have high ion conductivity at intermediate and low temperatures because of their low activation energy. Most of electrode infiltration studies for fuel electrode supported PCCs were carried out on a thin air electrode layer rather than a thick fuel electrode. In the present study, various metallic nanoparticles (such as Ni, Pd and Pt) were infiltrated in fuel electrode scaffolds to increase the thriple phase boundary (TPB, electrode-electrolyte-gas phase). The fabricated fuel electrode supported PCC consisted of Ni-BaCe0.7Zr0.1Y0.1Yb0.1O3-ẟ cermet fuel electrode, BaCe0.7Zr0.1Y0.1Yb0.1O3-ẟ (BCZYYb) electrolyte, and BCZYYb-La0.6Sr0.4Co0.2Fe0.8O3-ẟ composite air electrode. SEM analysis results revealed that metallic nanoparticles can be infiltrated up to the fuel electrode functional layer and their distribution was uniform through the layer. The PCC with metal nanoparticle infiltrated fuel electrode exhibited higher power density and lower polarization resistance than that with bare fuel electrode. This study shows the electrochemical performance of fuel electrode supported PCCs can be further improved by the facile infiltration method.

Electrosynthesis and Microanalysis in Thin Layer: An Electrochemical Pipette for Rapid Electrolysis and Mechanistic Study of Electrochemical Reactions.

Electrochemistry represents unique approaches for the promotion and mechanistic study of chemical reactions and has garnered increasing attention in different areas of chemistry. This expansion necessitates the enhancement of the traditional electrochemical cells that are intrinsically constrained by mass transport limitations. Herein, we present an approach for designing an electrochemical cell by limiting the reaction chamber to a thin layer of solution, comparable to the thickness of the diffusion layer. This thin layer electrode (TLE) provides a modular platform to bypass the constraints of traditional electrolysis cells and perform electrolysis reactions in the timescale of electroanalytical techniques. The utility of the TLE for electrosynthetic applications benchmarked using NHPI-mediated electrochemical C-H functionalization. The application of microscale electrolysis for the study of drug metabolites was showcased by elucidating the oxidation pathways of the paracetamol drug. Moreover, hosting a microelectrode in the TLE, was shown to enable real-time probing of the profiles of redox-active components of these rapid electrosynthesis reactions.

Electrosynthesis and Microanalysis in Thin Layer: An Electrochemical Pipette for Rapid Electrolysis and Mechanistic Study of Electrochemical Reactions

Electrochemistry represents unique approaches for the promotion and mechanistic study of chemical reactions and has garnered increasing attention in different areas of chemistry. This expansion necessitates the enhancement of the traditional electrochemical cells that are intrinsically constrained by mass transport limitations. Herein, we present an approach for designing an electrochemical cell by limiting the reaction chamber to a thin layer of solution, comparable to the thickness of the diffusion layer. This thin layer electrode (TLE) provides a modular platform to bypass the constraints of traditional electrolysis cells and perform electrolysis reactions in the timescale of electroanalytical techniques. The utility of the TLE for electrosynthetic applications benchmarked using NHPI‐mediated electrochemical C‐H functionalization. The application of microscale electrolysis for the study of drug metabolites was showcased by elucidating the oxidation pathways of the paracetamol drug. Moreover, hosting a microelectrode in the TLE, was shown to enable real‐time probing of the profiles of redox‐active components of these rapid electrosynthesis reactions.

Electrochemical Activation and NAP-XPS As Well As EIS Characterization of La0.31Sr0.58Ti0.97Ni0.03O3-δ Thin Film Electrode

To improve catalytic activity of LaxSr0.9-xTiyM1-yO3-δ, La1-xSrxCryM1-yO3-δ based materials, doping of perovskite B-site with metals (M) like Ni, Co, Mo or Cu has been proposed. It has been demonstrated, that at elevated temperatures and in reducing atmosphere these dopants exsolve to perovskite surface and form nanometer scale catalyst particles. Exsolution process could be accelerated by using electrochemical polarization. In the present study thin film La0.31Sr0.58Ti0.97Ni0.03O3-δ electrodes was prepared using pulsed laser deposition (PLD) technique. Current collectors were made from Pt (using magnetron sputtering) and placed under the thin film electrode layer. Electrodes were characterized using XPS and EIS method at near ambient pressure conditions (1-5 mbar) at 650 °C, activated electrochemically and characterized again to see the effect of activation. Changes on the electrochemical performance as well as on XPS data caused by electrochemical activation were observed and analyzed.

A thin Si nanowire network anode for high volumetric capacity and long-life lithium-ion batteries

Silicon nanowires (Si NWs) have been widely researched as the best alternative to graphite anodes for the next-generation of high-performance lithium-ion batteries (LIBs) owing to their high capacity and low discharge potential. However, growing binder-free Si NW anodes with adequate mass loading and stable capacity is severely limited by the low surface area of planar current collectors (CCs), and is particularly challenging to achieve on standard pure-Cu substrates due to the ubiquitous formation of Li+ inactive silicide phases. Here, the growth of densely-interwoven In-seeded Si NWs is facilitated by a thin-film of copper-silicide (CS) network in situ grown on a Cu-foil, allowing for a thin active NW layer (<10 µm thick) and high areal loading (≈1.04 mg/cm2) binder-free electrode architecture. The electrode exhibits an average Coulombic efficiency (CE) of >99.6% and stable performance for >900 cycles with ≈88.7% capacity retention. More significantly, it delivers a volumetric capacity of ≈1086.1 mA h/cm3 at 5C. The full-cell versus lithium manganese oxide (LMO) cathode delivers a capacity of ≈1177.1 mA h/g at 1C with a stable rate capability. This electrode architecture represents significant advances toward the development of binder-free Si NW electrodes for LIB application.

One-Pot Synthesis of Ruthenium-Based Nanocatalyst Using Reduced Graphene Oxide as Matrix for Electrochemical Synthesis of Ammonia.

Conventional ammonia production consumes significant energy and causes enormous carbon dioxide (CO2) emissions globally. To lower energy consumption and mitigate CO2 emissions, a facile, environmentally friendly, and cost-effective one-pot method for the synthesis of a ruthenium-based nitrogen reduction nanocatalyst has been developed using reduced graphene oxide (rGO) as a matrix. The nanocatalyst synthesis was based on a single-step simultaneous reduction of RuCl3 into ruthenium-based nanoparticles (Ru-based NPs) and graphene oxide (GO) into rGO using glucose as the reducing agent and stabilizer. The obtained ruthenium-based nanocatalyst with rGO as a matrix (Runano-based/rGO) has shown much higher catalytic activity at lower temperatures and pressures for ammonia synthesis than conventional iron catalysts. The rGO worked as a promising promoter for the electrochemical synthesis of ammonia due to its excellent electrical and thermal conductivity. The developed Runano-based/rGO nanocatalyst was characterized using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), ultraviolet-visible (UV-vis) absorption spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), inductively coupled plasma mass spectrometry (ICP-MS), and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the size of the Ru-based NPs on the surface of rGO was 1.9 ± 0.2 nm and the ruthenium content was 25.03 wt %. Bulk electrolysis measurements were conducted on thin-layer electrodes at various cathodic potentials in a N2-saturated 0.1 M H2SO4 electrolyte at room temperature. From the chronoamperometric measurements, the maximum faradic efficiency (F.E.) of 2.1% for ammonia production on the nanostructured Runano-based/rGO electrocatalyst was achieved at a potential of -0.20 V vs reversible hydrogen electrode (RHE). This electrocatalyst has attained a superior ammonia production rate of 9.14 μg·h-1·mgcat.-1. The results demonstrate the feasibility of reducing N2 into ammonia under ambient conditions and warrant further exploration of the nanostructured Runano-based/rGO for electrochemical ammonia synthesis.

Enhancement of the light output efficiency and thermal stability of AlGaN-based deep-ultraviolet light-emitting diodes with Ag-nanodot-based p-contacts and an 8-nm p-GaN cap layer.

The efficiency of AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) is limited by the high absorption issue of the p-GaN contact layer or poor contact properties of the transparent p-AlGaN contact layer. Enhancement of the light output efficiency and thermal stability of DUV LEDs with an emission wavelength of 272 nm was investigated in this work. Ag nanodots on an 8-nm p-GaN cap layer were used to form ohmic contact, and Al and Mg reflective mirrors were employed to enhance the light output power (LOP) of DUV LEDs. However, serious deterioration of LOP occurred after the high-temperature process for the LEDs with Al and Mg reflective mirrors, which can be attributed to the damage to the ohmic contact properties. A Ti barrier layer was inserted between the Ag/p-GaN and Al layers to prevent the degeneration of ohmic contact. The wall-plug efficiency (WPE) of DUV LEDs fabricated by the Ag-nanodot/Ti/Al electrode is 1.38 times that of LEDs fabricated by adopting a thick Ag layer/Ti/Al at 10 mA after a high-temperature process. The Ag-nanodot/Ti/Al electrode on thin p-GaN is a reliable technology to improve the WPE of DUV LEDs. The experimental and simulated results show that the ohmic contact is important for the hole-injection efficiency of the DUV LEDs when p-GaN is thin, and a slight increase in the contact barrier height will decrease the WPE drastically. The results highlighted the importance of thermally stable ohmic contacts to achieve high-efficiency DUV LEDs and demonstrated a feasible route for improving the LOP of DUV LEDs with a thin p-GaN cap layer and stable reflective electrodes.

Appraisal the effective diffusion coefficients of Li-ions by PITT and network thermodynamic methods in thin-layer Fe-sulfidic electrodes of Li-accumulator

In this work, we explored the possibilities of network thermodynamics to determine the most important kinetic parameter of the diffusion process, the diffusion coefficient of lithium ions (DLi) in iron sulfide. Iron sulfides have been electrolytically synthesized in thin aluminum-based layers for implementation in miniature lithium batteries. A comparison is made of the results obtained by the method of network thermodynamics and the method of potentiostatic pulse titration PITT. The theoretical aspects of both methods are presented. The task was reduced to obtaining curves I (current) - time (t), their analysis and calculation of coefficient values (DLi), using the theoretical foundations of diffusion and the methods used. At the early stages of applying the method of network thermodynamics to the study of diffusion in lithium current sources, it was not clear why the method is suitable for determining DLi not in the entire working range of potentials. A wide range of studies using the PITT method helps to answer questions related to the application of the network thermodynamic method. When using both methods, it is important to establish the potential range with diffusion kinetics and to reveal the accompanying electrode processes. Thus, it was found that both methods used are unable to provide reliable results in the FexSy electrode potential range of 2.8–1.8 V, since the diffusion nature of the electrode process is not a priority in this potential range.

Adsorption of croconic acid anions at silver electrodes in sodium fluoride solutions. Interplay of DFT calculations and in situ ATR-SEIRAS measurements for the interpretation of experimental spectra of adsorbed species

The adsorption of species coming from the disodium salt of croconic acid (4,5-dihydroxy-4-cyclopentene-1,2,3-trione, H2C5O5) at chemically deposited silver electrodes was studied in aqueous sodium fluoride solutions by combining in situ ATR-SEIRAS (Surface-Enhanced Infrared Reflection Absorption Spectroscopy experiments under Attenuated Total Reflection conditions) and Density Functional Theory (DFT) calculations. Voltammetric experiments suggest the existence of reversible adsorption processes in the potential range between −0.55 and −0.20 V vs Ag/AgCl (KCl 1 M), whereas irreversible reduction is observed for potentials below-0.55 V. ATR-SEIRA spectra show potential-dependent adsorbate bands in the potential range for reversible adsorption, that were assigned according to DFT calculations. Calculated optimized geometry of adsorbed croconate and bicroconate correspond to bonding to the silver surface in a bidentate configuration through two oxygen atoms with the molecular plane perpendicular to the metal surface. The broadening and splitting at high electrode potentials of the CO stretching bands for adsorbates coming from croconic acid can be explained by invoking the existence of collective vibrational modes appearing at high coverage. In overall, the ATR-SEIRA spectra obtained with Ag thin layer electrodes resembles that reported for Au thin layers. As a difference, higher adsorbate coverage seems to be obtained in the case of silver. Moreover, a strong feature at ca. 1580 cm−1 is experimentally observed, that was much weaker on gold samples. The calculated frequencies for adsorbed croconate and bicroconate do not change significantly with the adsorption bonding sites for the optimized geometries. Taking into account the calculated frequencies of both types of species, a better agreement with the experimental behavior (including the splitting/shifting caused by dipole–dipole coupling in high-coverage collective modes) is obtained in the case of bicroconate. The coexistence with some adsorbed croconate species cannot be ruled out.

Development of thin electrode layers by spray coating for solid oxide cells

Development of thin electrode layers by spray coating for solid oxide cells

Operando Surface Enhanced Infrared Spectroscopic Investigations of Interfacial Restructuring and Oxygen Electrochemistry in Ionic Liquid Electrolytes for Metal-Air Batteries

Alkali metal-oxygen (M-O2) chemistry has received significant research interest as a promising next-generation battery, but many challenges need addressing before the technology can become viable in practice. Key among these obstacles are the understanding and control of the mechanisms of the oxygen reduction and evolution reactions (ORR and OER), and the tendency for the electrolyte materials to degrade due to attack by reactive intermediates. As such, a greater understanding of the ORR/OER in M-O2 cells, and how these factors contribute to the poor reversibility on cycling, is required in order to develop stable electrolytes.Attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) is highly sensitive to the interfacial region and can probe sub-monolayer adsorbates and species within ca. 10 nm of the electrode surface, which makes it valuable for studying interfacial processes. Our group demonstrated the application of ATR-SEIRAS to identify ORR products in nonaqueous M-O2 batteries, wherein a ZnSe prism internal reflection element (IRE) was utilised to extend the measurement range down to ca. 700 cm-1.1 While ZnSe offers enhanced optical properties over some conventional IREs, the lower wavenumber cut-off means that the sub-700 cm-1 vibrational frequencies of some superoxide and peroxide species and intermediates generated during ORR/OER cannot be observed. Recently, a micromachined Si wafer IRE has been developed to extend the measurement range of ATR-SEIRAS to well below 700 cm-1.2 In this work, we report ATR-SEIRAS investigations into the O2 electrochemistry and the potential dependent interfacial restructuring of 1-methyl-1-propylpyrrolidinium bis{(trifluoromethyl)sulfonyl}imide ([Pyrr13][TFSI]) utilising a thin-layer Au electrode on the micromachined Si wafer IRE to extend the measurement range towards the far-IR region. While the potential-dependent restructuring of the IL/Au electrode interface has been investigated by ATR-SEIRAS previously,3 the optical transmission of the Si wafer IRE used here reveals previously unreported changes in the 1000–500 cm-1 spectral region (Figure 1). We also discuss here how the redox couple of dissolved O2 strongly alters the double-layer restructuring, and the associated activation energy barriers, in the IL electrolyte. The ORR in the IL electrolyte in the presence of Li+ or Na+ cations is also explored, wherein the identification of sub-700cm-1 (su)peroxy intermediates/products, critical to understanding the overall mechanisms, is made possible using the Si wafer IRE. References J. P. Vivek, N. G. Berry, J. Zou, R. J. Nichols, and L. J. Hardwick, J. Phys. Chem. C, 121, 19657–19667 (2017).T. A. Morhart, B. Unni, M. J. Lardner, and I. J. Burgess, Anal. Chem., 89, 11818–11824 (2017).K. Motobayashi, Y. Shibamura, and K. Ikeda, Electrochem. Commun., 100, 117–120 (2019). Figure 1. Operando ATR-SEIRAS measurements of [Pyrr13][TFSI] (at a thin-layer Au electrode) at 0.9 V vs reference spectra at -2.7 V (dark blue and dark red spectra) at a) 1500-900 cm-1 and b) 860-500 cm-1. The Si wafer IRE (red spectrum) allows detection of [TFSI]- peaks below 1000 cm-1, which are not visible using the Si prism (light blue spectrum) due to the poor IR transmission in this region. Wafer spectra intensities are multiplied by a factor of 2 and the grey trace is an ex situ ATR-FTIR spectrum of the bulk IL. Figure 1

Design and demonstration of absorption/luminescence-compatible spectroelectrochemical cell with optically transparent thin-layer electrode

An optically transparent thin-layer electrode (OTTLE) cell compatible with both absorption and luminescence spectroelectrochemistry was developed. An octagonal quartz prism with a slit to insert a Pt mesh working electrode allows 2 orientations with 90° and 45° versus incident lights from the absorption and luminescence spectrophotometers, respectively. As a result, both spectroelectrochemical experiments can be operated using this single OTTLE cell. [Ru(bpy) 3 ] 2+/3+ was employed for demonstration of our cell in the absorption and luminescence spectroelectrochemical experiments as well as a preliminary electrochemical survey using cyclic voltammetry. Consequently, the Nernstian response of the [Ru(bpy) 3 ] 2+/3+ redox couple was observed as expected in any of the experiments, demonstrating that the current cell quantitatively works for both absorption and luminescence spectroelectrochemistry.

Oxygen Reduction Reaction Kinetics on a Pt Thin Layer Electrode in Aemfc

Oxygen Reduction Reaction Kinetics on a Pt Thin Layer Electrode in Aemfc

Deposited Layers as Negative Electrodes for Lithium Ion Batteries

The battery usage increases every year. The batteries help with development of mobility both from point of view of portable electronic and from view of goods and people transport in electromobility. One of the main parameters is gravimetric and volumetric capacity, which we are trying continually increase. One of the main ways is to change current used material by new ones with better parameters. One of possibilities is to use thin layer and so-called battery conversion principle. Electrodes works on conversion principle have usual higher capacities. The main disadvantage of such system is large volume change of electrode material due charging and discharging. This can be partly solved by special 3D structure which compensate the volume changes. This work focusses on preparing basic thin layer electrode by help of electrodeposition. The electrodes are then cycled against lithium.

Analysis Method of Oxygen Reduction Reaction Rate in PEFC Using Pt-Sputtered Catalyst

For widespread use of polymer electrolyte fuel cell (PEFC), it is necessary to reduce the amount of platinum by optimizing the cathode catalyst layer (CCL) structure. Therefore, oxygen reduction reaction (ORR) rate which does not include the mass transfer resistance in CCL should be formulated. To measure the ORR rate which does not include the mass transfer resistance in the CCL, a thin layer electrode was prepared by directly sputtering platinum to microporous layer (MPL) on gas diffusion layer. Dependencies of ORR rate on temperature and relative humidity (RH), were measured and analyzed. From the measurement results, ORR parameters which do not include the effect of mass transfer resistance through the CCL were appropriately determined. The ORR rate and electrochemical surface area (ECSA) depend on RH and a half of RH dependency of ORR rate is ascribed to change in ECSA.

The Effect of Thin Functional Electrode Layers on Characteristics of Intermediate Temperature Solid Oxide Fuel Cell

The thin-film multilayer structure of the membrane-electrode assembly in a solid oxide fuel cell which involves a NiO/ZrO2:Y2O3 anode functional layer and a La0.6Sr0.4CoO3 cathode functional layer and also a bilayer ZrO2:Y2O3/Ce0.9Gd0.1O1.95 electrolyte is formed by magnetron sputtering onto a supporting NiO/ZrO2:Y2O3 anode. The effect of the functional electrode layers involved in the structure of a solid oxide fuel cell on its efficiency is studied. The volt–ampere characteristics of multilayer fuel cells are studied in the temperature range of 800–600°C. It is shown that the inclusion of a thin (600 nm thick) cathode functional layer into the structure of the membrane–electrode assembly enhances the fuel cell efficiency by reducing the polarization losses on electrodes. The maximum power density of the fuel cell with the cathode functional layer is 2290 and 500 mW/cm2 at 800 and 600°С, respectively. The simultaneous presence of anode and cathode functional layers is found to be unwelcome because gives rise to diffusion limitations on the anode.

Optimization of Boron-Doped Diamond Thin-Layer Cell for Chemical Oxygen Demand Sensor Based on Anodic Oxidation of Organics

The advanced electrochemical oxidation process (AEOPs) has been considered as an appealing approach to overcome problems associated with the conventional water treatment methods. The use of expensive and toxic chemical oxidizing reagents in chemical oxygen demand, for example, can lead to environmental concerns of the production of secondary pollution. Anodic oxidation, one of the most popular AEOPs, offers a rapid and straightforward COD determination by removing the need for chemical oxidants. The process mainly relies on the anode material to degrade the organic molecules; thus, choosing the appropriate material is one of the keys to a successful electrochemical oxidation.Numerous electrochemical applications utilize boron-doped diamond as the anode material due to its unique properties such as wide potential window, low background current, and resistance to fouling. The employment of BDD for anodic oxidation of organics enables complete oxidation of organics via physically adsorbed hydroxyl radicals (●OH). The species offers a high standard redox potential of E° (●OH/H2O) = 2.80 V/SHE, high reactivity, and short lifetime, makes it possible to be used for the on-site electrochemical oxidation process.The objective of this study is to develop and optimize an electrochemical system for chemical oxygen demand determination based on a photoelectrochemical degradation principle. The degradation of phenols takes place in a specially designed BDD thin-layer electrode, and the amount of electrons transferred at the electrode can be measured to define the equivalent COD value. A 60μm thick films are used as a spacer, resulting in a contact area of 3 cm2. At 2.54 V vs. SHE, a sample containing 50 mg/L analytes required less than 3 mins to degrade, and the assay time for organics decay increases for a higher concentration of phenols. Incorporating the BDD electrode with cathode materials, such as Pt-coated indium tin oxide (ITO), will be employed as an attempt to improve the degradation efficiency by minimizing the voltage drop between the electrodes. Sandwiching the BDD-cathode using Nafion® membrane will be studied to remove the need for additional supporting electrolytes. The major experimental conditions of the anodic oxidation of organic molecules by BDD, such as applied potential bias, supporting electrolyte concentration, pH, and dissolved oxygen concentration, will be varied to obtain the optimum conditions.