Oxygen Electrode Research Articles

Developing advanced oxygen electrodes for reversible protonic ceramic electrochemical cells via controlled bismuth doping on diverse perovskite lattice positions

The development of reversible protonic ceramic electrochemical cells (R-PCECs) is hampered by insufficient oxygen electrode activity. This study addresses this challenge by introducing bismuth (Bi) into different lattice sites (A-site, B-site, or both) of Ba(Co0.7Fe0.3)0.85Ta0.15O3-δ (BCFT) to develop novel oxygen electrode materials. Extensive characterizations and density functional theory calculations demonstrate that introducing Bi onto the B-site promotes oxygen vacancy formation and hydration, facilitates proton transportation and improves oxygen exchange ability, leading to the enhanced catalytic activity. In contrast, Bi on the A-site hinders performance. R-PCEC using Ba(Co0.7Fe0.3)0.75Bi0.10Ta0.15O3-δ (B-BCFT) oxygen electrode achieves exceptional performance in fuel cell (1.485 W cm−2 at 650 °C) and electrolysis modes (−1.839 A cm−2 at 1.4 V and 650 °C). Notably, B-BCFT demonstrates outstanding operational stability, lasting for 150 h in both modes and enduring 35 cycles of reversible operation. These results make B-BCFT a promising oxygen electrode material candidate for R-PCECs.

Developing high-performance oxygen electrodes for intermediate solid oxide cells (SOC) prepared by Ce0.8Gd0.2O2−δ backbone infiltration

Gd0.2Ce0.8O 2−δ (GDC) porous backbone infiltration with La0.6Sr0.4CoO3−δ (LSC), PrOx and LSC: PrOx as a composite oxygen electrode for intermediate solid oxide cells are conducted within the scope of this work. Samples were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and electrochemical impedance spectroscopy (EIS). A uniform distribution of the infiltrated material inside the backbone and at the electrolyte-backbone interface was achieved. EIS measurements on the prepared symmetrical samples showed electrode polarization resistance (Rp) values of 0.029 Ω.cm², 0.23 Ω.cm², and 0.44 Ω.cm² for LSC, LSC: PrOx, and PrOx at 600 °C, respectively. Long-term stability measurements at 600 °C for 100 h showed a slight increase in polarization resistance during the measurement period. Fuel cell measurements of commercial cells (Elcogen) with porous oxygen electrode consisting of GDC infiltrated with LSC showed an increase in power density compared to the reference cell with a value of 0.53 W.cm− 2 obtained at 600 °C. It is proven that infiltration via polymeric precursor into porous scaffolds as backbone oxygen electrode layer is effective and convenient method to develop high performance and stable solid oxide cells.

Highly active and stable oxygen electrode PrBaCo2O5+δ-Ba2CoWO6 enabled by In Situ formed misfit dislocation interface for reversible solid oxide cell

The energy conversion efficiency and durability of the reversible solid oxide cell (RSOC) is restricted by the development of highly active and stable oxygen electrode. Herein, an in-situ formed composite PrBaCo2O5+δ-Ba2CoWO6 oxygen electrode is proposed, which consists of a highly active A-site double perovskite (A-DP) phase and a stable B-site double perovskite (B-DP) phase. Misfit dislocation interface is formed between these two phases, exerting lattice tensile stress on the A-DP phase, which enhances catalytic activity and inhibits Ba segregation. Additionally, the B-DP phase suppresses lattice expansion of A-DP phase through the dislocation interface, thereby improving thermo-mechanical stability. Consequently, the composite electrode demonstrates a low polarization resistance of 0.056 Ω cm2 at 650 °C, impressive stability at 650 °C for 500 h in symmetrical cell tests, and excellent thermal-mechanical stability under 29 thermal cycles. A maximum power density of 0.75 W cm−2 and an electrolysis current density of 0.84 A cm−2 at 1.3 V were achieved at 650 °C by the composite electrode on a 260 μm-electrolyte supported cell configuration, which surpass most of the reported oxygen electrode materials. Furthermore, the cell exhibits excellent operational stability, with low degradation rates of 0.49 × 10−1 mV h−1 and 1.5 × 10−1 mV h−1 in fuel cell and electrolysis cell modes, respectively. This work offers an effective method for designing highly active and stable oxygen electrodes for RSOCs.

Reversible Long-Term Operation of a MK35x Electrolyte-Supported Solid Oxide Cell-Based Stack

High-temperature reversible solid oxide cells (rSOC) combine electrolyzer and fuel cell in one process unit which promises economic advantages with unrivaled high electrical efficiencies. However, large temperature gradients during dynamic rSOC operation can increase the risk of mechanical failure. Here, the degradation behavior of a 10-cell stack of the type “MK35x” with chromium-iron-yttrium (CFY) interconnects and electrolyte-supported cells (ESC) developed at Fraunhofer IKTS was investigated in rSOC operation at DLR. Its degradation was evaluated during nominal rSOC operation for more than 3400 h with 137 switching cycles between solid oxide fuel cell and solid oxide electrolysis cell operation of 24 h reflecting intermittent availability of solar energy. The voltage degradation rates of +0.58%/kh and −1.23%/kh in electrolysis and fuel cell operation, respectively, are among the lowest reported in literature. Comparison to a previously published long-term test in steam electrolysis did not show any indication for an increased degradation. Electrochemical impedance spectroscopy measurements were performed for all repeat units to evaluate the degradation behavior in detail. An overall polarization resistance decrease due to an improvement of the oxygen electrode was observed during electrolysis operation but was absent during fuel cell operation.

Anion-cation coupled electrolyte additive enhancing the performance of lithium-oxygen batteries

The rational design of electrolyte via introducing additive is an efficient strategy to improve the electrochemical performance of lithium-oxygen batteries (LOBs). In this work, coupling LiCl and Sn(TFSI)2 as the anion-cation electrolyte additive achieved the high-performance of LOBs by promoting the oxygen electrode reactions, regulating the Li+ solvation structure, and inducing the growth of the SEI protective layer. Specifically, Cl− with strong coordination affinity to Li+ could weaken the binding between Li+ and TEGDME solvent molecules, leading to the formation of an anion-dominant Li+ solvation structure, which facilitates the diffusion of Li+ in the electrolyte bulk and electrolyte/electrode interface. On the other hand, Sn2+ can serve as a redox mediator to catalyze ORR on the cathode and participate in the growth of smooth and dense SEI protective layer on Li metal anode surface, thus effectively promoting the oxygen electrode reaction kinetics and suppressing the corrosion of Li anode. As a consequence, the LOBs with coupled LiCl and Sn(TFSI)2 additive exhibited a ultra-high discharge capacity of 21517.1 mA h g−1 and an excellent cycling life of 334 cycles. This work provides a deep understanding for designing efficient electrolyte with additive for LOBs.

Manipulating Electron Delocalization of Metal Sites via a High-Entropy Strategy for Accelerating Oxygen Electrode Reactions in Lithium-Oxygen Batteries.

High-entropy perovskite oxides, in which the B-type metal site of perovskite oxides (ABO3) is occupied by over five kinds of transition metal ions, show promising applications in energy storage and conversion fields. Herein, high-entropy perovskite oxides (LaSr(5TM)O3) composed of Cr, Mn, Fe, Co, and Ni at the B-type metal site are prepared as oxygen electrocatalysts for Li-O2 batteries. The presence of compressive strain in LaSr(5TM)O3 effectively regulates the 3d orbit occupancy of the active Co site (Co2+ → Co3+) and lifts the energy level of the Co d-band center, thus leading to enhanced adsorption toward the LiO2 intermediate on Co sites. Furthermore, the high electron-drawing capability of Cr sites ensures sufficient electron exchange and further strengthens the adsorption of LiO2. As expected, the Li-O2 battery with a LaSr(5TM)O3 electrode delivers a low overpotential (0.79 V) and superior cyclability (226 cycles). This study provides a meaningful strain strategy to improve the electrocatalytic activity of multicomponent oxides via fabricating high-entropy materials.

Enhancement of the electrochemical properties for La0.6Sr0.4Co0.2Fe0.8O3−δ oxygen electrode by the addition of CaxCo4O9+δ nano-catalysts

Enhancement of the electrochemical properties for La0.6Sr0.4Co0.2Fe0.8O3−δ oxygen electrode by the addition of CaxCo4O9+δ nano-catalysts

Robust oxygen adsorbent mediated oxygen redox reactions for high performance lithium-oxygen battery

Lithium-oxygen batteries (LOBs) have been widely studied because of their ultra-high energy density (∼3500 Wh kg−1). However, the reversibility and stability of LOBs are greatly limited by the sluggish kinetics of oxygen reduction/evolution reactions (ORR/OER) and severely parasitic reactions on oxygen electrodes. Electrolyte in LOBs plays an important role in the transport of reactive oxygen species and Li+, which greatly affects the kinetics and reversibility of the charging and discharging processes of batteries. In this work, perfluorooctane (PFO) is used as the additive in 1.0 M LiTFSI/TEGDEM electrolyte for LOBs to regulate the kinetics of oxygen electrode reactions. Due to the strong adsorption ability of PE toward oxygen, the oxygen concentration inside the electrolyte is greatly increased after the addition of PE. In addition, the PE-added electrolyte also exhibits superior electrochemical stability and is capable of triggering solution-mediated Li2O2 growth pathway during the discharge process of the LOBs. Therefore, with the increased oxygen concentration and the optimized electrode/electrolyte interface, the ORR/OER kinetics on the oxygen electrode is significantly promoted, which enables the LOBs with excellent energy efficiency and cycling life. This work provides a new idea for the design of oxygen-rich and high-performance electrolyte for lithium-oxygen batteries.

Interface engineering of La0.6Sr0.4Co0.2Fe0.8O3−δ/Gd0.1Ce0.9O1.95 heterostructure oxygen electrode for solid oxide electrolysis cells with enhanced CO2 electrolysis performance

For CO2 electrolysis in solid oxide electrolysis cells (SOECs), oxygen evolution reaction in the oxygen electrode limits the electrolysis process due to its slower reaction kinetics. Composite oxygen electrodes with good uniformity and interfacial connectivity are expected to promote the charge carriers' transport effectively and thus increase the electrocatalytic performance of the cell. In this work, interface engineering is applied to promote the conventional La0.6Sr0.4Co0.2Fe0.8O3−δ-Gd0.1Ce0.9O1.95 (LSCF-GDC) composite oxygen electrode to form a heterostructure via co-synthesis method. The results prove that LSCF co-synthesized with 40 wt%GDC (LSCF/40GDC) exhibits higher conductivity and faster oxygen exchange kinetics and bulk diffusion processes. The nickel/yttria stabilized zirconia (Ni-YSZ) supported cell with LSCF/40GDC oxygen electrode could approach an impressive CO2 electrolysis current density of 2.6 A·cm−2 at 1.6 V and 800 °C. Meanwhile the cell can operate at 1.5 V and 750 °C with electrolysis current density of 1.3 A·cm−2 for more than 100 h without apparent degradation. This heterostructure enhances the interfacial bonding strength between LSCF and GDC phases, thereby providing a continuous network structure for electron and ion transport. Such an interface engineering via co-synthesis method offers a straightforward and convenient modification for oxygen electrodes, providing an alternative route for advanced materials development of CO2 electrolysis.

Effect of long-term ethanol consumption and a high-fat diet on mitochondrial respiration in rat pancreatic acinar cells and hepatocytes

Chronic alcohol consumption may cause pancreatitis and alcohol-related liver diseases. Both adaptation and damage of liver mitochondria in animals on chronic ethanol and high-fat diets were demonstrated. It is currently not clear if ethanol or its metabolites such as fatty acid ethyl esters can cause mitochondrial damage to the pancreas. The present study aimed to evaluate the effect of chronic ethanol administration in combination with a high-fat diet on mitochondrial respiration in both pancreatic acinar cells and hepatocytes of rats. Wistar male rats on a high-fat diet (35% calories) were administered ethanol (6 g/kg body weight) by oral gavage for 14 days. Pancreatic acini cells and hepatocytes were isolated with collagenase digestion. The respiration of isolated cells was studied with a Clark electrode. Ethanol administration to rats kept on a high-fat diet was followed by a rapid loss of animal weight during the first 5 days of the experiment and diminished secretory response of pancreatic acini to acetylcholine, however, no changes in acinar cells ultrastructure, basal, oligomycin-insensitive or FCCP-uncoupled respiration were found. Meanwhile ethanol caused a significant (~40%) increase in basal and maximal FCCP-uncoupled respiration rate of isolated hepatocytes. In conclusion, chronic ethanol administration to rats on a high-fat diet does not cause mitochondrial damage in the pancreas, while mitochondria of the liver adapt to ethanol by increasing respiration rate. Keywords: ethanol, hepatocytes, high fat diet, mitochondrial respiration, pancreatic acinar cells

Changes in bioenergetic characteristics of the murine lymphoma cells under the action of a thiazole derivative in complex with polymeric nanoparticles

Background. Mitochondria can influence cancer cells both indirectly via reactive oxygen species mediation and directly through mitochondrial biogenesis. Energy production in mitochondria is crucial as it facilitates the synthesis of essential molecules needed for cellular biosynthesis, growth, and proliferation. The development of new anticancer drugs that target the energy metabolism of tumor cells shows promise in cancer treatment. Our study aimed to investigate how the thiazole derivative N-(5-benzyl-1,3-thiazol-2-yl)-3,5-dimethyl-1-benzofuran-2-carboxamide (BF1), the polymeric nanoparticles based on the polyethylene glycol (PEG-PN, Th5), and their complex with BF1 (Th6) affect respiration and mitochondrial membrane potential in murine NK/Ly tumor cells. Materials and Methods. The study was performed on white wild-type male mice with grafted NK/Ly lymphoma. The test substances were added to the cell suspension at a final concentration of 10 μM and incubated for 15 min at 37 °C. Oxygen uptake rates in NK/Ly cells were measured using a polarographic method with Clark electrode. Changes in mitochondrial membrane potential were assessed using the tetramethylrhodamine methyl ester fluorescence dye. The fluorescence intensity was evaluated using the ImageJ computer program. Results. After incubating NK/Ly cells with BF1 (10 µM), Th5, or the BF1 + PEG-PN complex (Th6) for 15 min, no changes were observed in glucose-fueled basal respiration. However, the Th6 complex significantly activated FCCP-stimulated respiratory processes in NK/Ly lymphoma cells. Fluorescent microscopy data indicated that BF1 or Th5 alone did not affect mitochondrial membrane potential values. However, the Th6 complex significantly decreased mitochondrial membrane potential, suggesting a reduction in NK/Ly cell viability. Conclusions The investigated complex of thiazole derivative BF1 with PEG-based polymeric nanoparticles may realize its cytotoxic effect by depolarization of mitochondrial membrane in NK/Ly lymphoma cells.

An efficient electrode for reversible oxygen reduction/evolution and ethylene electro-production on protonic ceramic electrochemical cells

Protonic ceramic electrochemical cells (PCECs) have demonstrated great promise for applications in the generation of electricity, and the synthesis of chemicals (for example, ethylene). However, enhancing the electrochemical reactions kinetics and stability of PCECs electrodes is one grand challenge. Here, we present a novel electrode material via a co-doping of cesium (Cs) and niobium (Nb) on PrBaCo2O6−δ with the composition of PrBa0.9Cs0.1Co1.9Nb0.1O6−δ (PBCCN), which naturally decomposes into dual phases of a double-perovskite PBCCN (DP-PBCCN, ∼92.3 wt%) and a single-perovskite Ba0.9Cs0.1Co0.95Nb0.05O3−δ (SP-BCCN, ∼7.7 wt%) under typical powder processing conditions. PBCCN exhibits a low area-specific resistance (ASR) value of 0.107 Ω cm2, an outstanding performance of 2.04 W cm−2 in fuel cell (FC) mode, a current density of −2.84 A cm−2 at 1.3 V in electrolysis cell (EC) mode, and promising reversible operational durability of 53 cycles in ∼212 h at +/− 0.5 A cm−2 and 650 °C. Cs doping generates more oxygen vacancies and accelerates the oxygen exchange kinetics, while Nb doping effectively enhances the stability, as illustrated by the analyses of X-ray photoelectron spectroscopy, and electrical conductivity relaxations. When applied as the positrode for electrochemical non-oxidative dehydrogenation of ethane (C2H6) to ethylene (C2H4) on PCECs, it displays an encouraging C2H6 conversion of 12.75% and a C2H4 selectivity of 98.4% at 1.2 V.

Investigation of membrane-electrode assembly parameters for double-layer anion-exchange membrane-unitized regenerative fuel cell

In this study, we investigate various membrane-electrode assembly (MEA) parameters in the oxygen and hydrogen electrodes for high-efficiency anion-exchange membrane-unitized regenerative fuel cell (AEM_URFC). The effects of catalyst loadings, types of porous transport layer (PTL), and oxygen and hydrogen catalysts were optimized to improve the efficiency of the AEM_URFC. The PTL results indicated that the PTL suitable for fuel cell (FC) exhibited high round-trip efficiency (RTE). Additionally, the types of hydrogen electrode (Pt/C and PtRu/C) were examined. Additionally, AEM_URFCs with different oxygen reduction reaction (ORR) catalyst types (Pt/C and Pt black), and ORR and oxygen evolution reaction catalyst loadings were evaluated. Through our investigations, we developed a high-efficiency AEM_URFC with an RTE of 65.9 % at 20 mA cm−2 (0.871 and 1.572 V (FC and WE modes, respectively)). Moreover, the performance of this AEM_URFC is superior to that of other AEM_URFCs reported in the literature, which is attributed to the reduced ohmic resistance loss caused by the electrical conductivity and hydrophobicity of carbon PTL. Moreover, the AEM_URFC was durable for 5 cycles, indicating that it is cyclable under URFC operation.

MnS doping regulating Co active sites on fibrous cobalt nitride as bifunctional oxygen electrocatalyst for high-performance Zn-air battery

Aiming to achieve high-efficiency bifunctional catalysts, doping engineering is applied to construct bifunctional catalysts for oxygen electrodes in Zn-air batteries to strengthen the catalytic kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, MnS doped cobalt nitride catalyst (MnS/CoNx) with divergent fiber morphology is prepared by low temperature nitriding for the self-assembling layered double hydroxides (LDH). The MnS/CoNx shows excellent electrical conductivity and improved catalytic activity on ORR and OER with low overpotential of 290 mV at 10 mA cm−2 and a good half-wave potential of 0.80 V in ORR compared with CoNx and MnO/CoNx. The contribution of the increased bifunctional catalytic performance is possible from the more active center Co3+ and Mn4+, and the elevated electron transport resulted from the opportune high conductive MnS doping. The MnS/CoNx catalyst-driven Zn-air battery achieves a higher power density of 228 mW cm−2 and the excellent long-term stability of 500 h at 20 mA cm−2 far surpassing the commercial Pt/C+RuO2 catalyst.

Electrocatalysis of hydrogen and oxygen electrode reactions in alkaline media by Rh-modified polycrystalline Ni electrode

Developing novel electrocatalysts for energy conversion applications is of utmost importance for reaching the energy security of modern society. Here we present a comprehensive investigation of rhodium-modified polycrystalline nickel as an electrocatalyst for hydrogen and oxygen electrode reactions in alkaline media. The surface modification of nickel electrodes was achieved by facile galvanic displacement (up to 30 s) from a highly concentrated acidic Rh3+ solution. The results demonstrate a significant enhancement in the electrocatalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on the Rh-modified Ni electrodes, positioning galvanic displacement as a viable approach to engineering advanced electrocatalysts for clean energy applications. On the other hand, the hydrogen oxidation (HOR) and oxygen reduction reaction (ORR) activities of the Rh-modified electrodes are lower compared to polycrystalline platinum. It is suggested that semiconducting Rh2O3 has a detrimental role on the HOR and ORR performance, while the activities of HER and OER, dominantly taking place on metallic Rh and conductive RhO2, are very high. This research sheds light on the mechanisms underlying the enhanced electrode kinetics on Rh-modified Ni electrodes and provides insights into the development of efficient and cost-effective electrocatalysts for renewable energy technologies.

An Efficient Trifunctional Spinel-Based Electrode for Oxygen Reduction/Evolution Reactions and Nonoxidative Ethane Dehydrogenation on Protonic Ceramic Electrochemical Cells.

Protonic ceramic electrochemical cells (PCECs) have received considerable attention as they can directly generate electricity and/or produce chemicals. Development of the electrodes with the trifunctionalities of oxygen reduction/evolution and nonoxidative ethane dehydrogenation is yet challenging. Here these findings are reported in the design of trifunctional electrodes for PCECs with a detailed composition of Mn0.9Cs0.1Co2O4-δ (MCCO) and Co3O4 (CO) (MCCO-CO, 8:2 mass ratio). At 600°C, the MCCO-CO electrode exhibits a low area-specific resistance of 0.382 Ω cm2 and reasonable stability for ≈105h with no obvious degradation. The single cell with the MCCO-CO electrode shows an encouraging peak power density of 1.73W cm-2 in the fuel cell (FC) mode and a current density of -3.93 A cm-2 at 1.3V in the electrolysis cell (EC) mode at 700°C. Moreover, the MCCO-CO cell displays promising operational stability in FC mode (223h), EC mode (209h), and reversible cycling stability (52 cycles, 208h) at 650°C. The MCCO-CO single cell shows an encouraging ethaneconversion to ethylene (with a conversion of 40.3% and selectivity of 94%) and excellent H2 production rates of 4.65mL min-1 cm-2 at 1.5V and 700°C, respectively, with reasonable Faradaic efficiencies.

Boosting the performance of La0.5Sr0.5Fe0.9Mo0.1O3-δ oxygen electrode via surface-decoration with Pr6O11 nano-catalysts

Cobalt-free La0.5Sr0.5Fe0.9Mo0.1O3-δ (LSFM) oxide is particularly investigated as a durable and efficient oxygen electrode material for the reversible solid oxide cells (RSOCs) in this study. Pr6O11 nano-catalysts are introduced into LSFM oxygen electrode as synergistic catalysts to enhance and optimize the electrode reactions. Results demonstrate an effectively promoted oxygen reduction and evolution reaction kinetics of the Pr6O11 decorated LSFM electrode. Polarization resistances (Rp) of LSFM electrode are dramatically reduced with the increasing Pr6O11 nano-catalysts and the lowest Rp of 0.039 Ω cm2 is obtained at 800 °C, which is ∼97% lower than that of the LSFM electrode. The Pr6O11 decorated LSFM oxygen electrode also displays a superior durability under cyclic anodic and cathodic polarizations. Furthermore, both the maximum power density and electrolytic current density of the Pr6O11 decorated cell are more than 2 times that of the LSFM cell. Results make clear reliability of the Pr6O11 decorated LSFM to be a promising oxygen electrode for RSOCs.

Utilization of a Clark electrode device as a respirometer for small insects: A convincing test on ants allowing to detect discontinuous gas exchange

Respirometry provides a direct measure of an organism’s O2 consumption rate (VO2), which is a significant component of its metabolic rate (energy expenditure). Amongst ants, variations in lifespan between different social castes (such as workers and queens) can be substantial, varying depending on the species. As metabolic rate is higher in short-living species, we aimed to determine how VO2 and longevity may have coevolved within ant casts. Measuring VO2 in such tiny animal models can be challenging, and as a first methodological step, we validate the use of a Clark electrode, initially designed for measuring mitochondrial respiration control pathways, for assessing VO2 in ants within a sealed chamber. This was done by comparing it with stop-flow VO2 and CO2 production, using a traditional indirect calorimetry device. The global aim is to provide a reliable protocol to conduct accurate comparisons of metabolic rates within and among ant species. As expected, using the Clark electrode entails high time resolution and revealed that queens and workers exhibited discontinuous gas exchange, with episodes of apnea lasting up to 20 min.

Quantification of lactic acid in wines using an amperometric biosensor

The objective of this study was to develop an analytical method that allows for the rapid and cost-effective detection and quantification of lactic acid in wines. The analysis of lactic acid is a time-consuming and costly process in the food industry. Therefore, the use of an enzymatic amperometric sensor that employs lactate oxidase (LacOx) immobilized on an oxygen electrode enabled the determination of lactic acid in wine. This study utilizes a voltage of −500mV and recorded the amperometric signal was obtained during oxygen consumption while lactic acid oxidation occurred in the sensor reactor. The detection time was at 10 s. A positive linear relationship was obtained between oxygen consumed as a function of time (mg O2/L x s−1). The lactic acid concentration ranged from 1 to 7 mM with a coefficient R2 = 0.994. The sensor exhibited good specificity KM = 0.675. The immobilized enzyme retained over 85% activity for 60 days, allowing for the reuse of the previously modified membrane up to 22 times. In comparison to other methods documented in the literature, the results demonstrate a favourable analytical quality. Furthermore, other aspects, such as the low residual formation, also exhibit a positive outcome. The analysis of lactic acid showed good correlation when compared to HPLC methodology, which occupies the same linear range. This validates the use of the sensor as an alternative method for quantifying lactic acid in wine. The value of this study lies in its presentation of a technique that is more straightforward to implement than traditional methods for quantifying lactic acid in grape wines.

Reactive oxygen species, electrode potential and pH affect CoCrMo alloy corrosion and semiconducting behavior in simulated inflammatory environments

Crevice corrosion in modular taper junctions of hip or knee replacements using cobalt-chrome-molybdenum (CoCrMo) alloys remains a clinical concern. Non-mechanically-driven corrosion has been less explored compared to mechanically assisted crevice corrosion. This study hypothesized that solution chemistry within crevices, inflammation, and cathodic electrode potential shifts during fretting result in low pH and generate reactive oxygen species (ROS), affecting oxide film behavior. This study investigated how resistance and capacitance of the CoCrMo oxide film (i.e., corrosion resistance) are modified in simulated in vivo crevice environments of modular taper junctions. Six solutions were evaluated (two pH levels: 1 and 7.4 and four hydrogen peroxide (H2O2) concentrations: 0, 0.001, 0.01 and 0.1 M). Rp versus voltage and Mott–Schottky plots were created from symmetry-based electrochemical impedance spectroscopy (sbEIS). At pH 1, the semiconductor transition to p-type occurs at more anodic potentials and higher flat band potentials were found. H2O2 decreased the flat band potential and slope in the Mott–Schottky plot. Higher H2O2 in pH 7.4 solution significantly modified the oxide film, leading to increased donor density (p = 0.0004) and a 150-fold reduction in Rp in the cathodic potential range at -1 V (p = 0.0005). The most unfavorable condition (0.1 M H2O2 pH 1) resulted in a 250-fold lower resistance compared to phosphate buffered saline (PBS) pH 7.4 at -1 V (p = 0.0013). This study highlights the corrosion susceptibility of CoCrMo under adverse chemical and potential conditions, identifying increased defects in the oxide film due to ROS, hydrogen ions and electrode potential. Statement of significanceCorrosion of cobalt chrome molybdenum alloy caused by direct chemical attack in the crevice region of hip replacements, such as modular taper junctions, remains a clinical concern. The junction environment contains adverse chemical compositions, including high acidity and reactive oxygen species (ROS) due to inflammatory responses against the corrosion products. We simulate inflammatory environments with different pH levels and hydrogen peroxide, representative of ROS. We employ electrochemical impedance spectroscopy and apply stepwise voltage over the range induced by tribocorrosion processes. We relate the effect of adverse chemical components on corrosion and semiconducting behavior of the oxide film using Mott–Schottky analysis. This study shows how pH and ROS concentration compromises the oxide film potentially leading to non-mechanically induced corrosion.