Oxygen Ion Transport Research Articles

Fabrication and Characterization of a Composite Ni-SDC Fuel Cell Cathode Reinforced by Ni Foam.

High-temperature fuel cells (namely, molten carbonate and solid oxide; MCFCs and SOFCs) require the cathode to be designed to maximize oxygen catalytic reduction, oxygen ion transport, electrical conductivity, and gas transport. This then leads to the optimization of the volume fraction and morphology of phases, as they are a pathway for electrons, ions, and gases to be continuous and self-interpenetrating. Apart from the functional properties, the cathode must be mechanically stable to prevent cracking during fuel cell assembly and operation. The manufacturing process of the composite cathode was optimized to meet such requirements in this research work. The tape casting technique and further firing process were used to fabricate the cathodes. The slurry for the green tape was composed of nickel (Ni), cerium oxide doped with samarium oxide (SDC), water (solvent), and an organic binder (which becomes pore space after firing). Each of these elements is necessary for the effective transport of specific species: electrons, oxygen, ions, and gas particles, respectively. Moreover, the nickel foam was embedded into the powder-based structure to improve mechanical strength. The study involved many technological issues, such as the effect of the SDC fraction on the cathode microstructure, mechanical strength, and chemical stability at high temperatures, and also involved environmental issues.

Electrical Conductivity of LSM—YSZ Oxygen Electrode for Determining Active Electrode Zone in Solid Oxide Cells

Solid oxide cells (SOCs) show high potential in applications related to sustainable society. The substantial contribution of the SOCs is their high efficiency in terms of the electric energy utilization due to the operating temperature up to 800 °C. The effect of high operation temperature is favorable in two ways. Firstly, it accelerates the kinetics of electrochemical reactions preventing the need of the use of Pt-based catalysts. Secondly, the high temperature offers favorable thermodynamic conditions decreasing the equilibrium potential for water splitting. This makes the SOCs technology a direct competitor to low-temperature technologies, such as alkaline or PEM electrolysis.The SOCs are composed of electrolyte, fuel electrode and oxygen electrode. The electrolyte allows transport of oxygen ions between the electrodes due to its high ionic conductivity. Yttria-stabilized zirconia (YSZ) represents a typical example of such a material. The oxygen electrode is where the oxygen reduction reaction or the oxygen evolution reaction takes place according to the operation mode of the SOC. Lanthanum strontium manganite (LSM) has been the state-of-the-art oxygen electrode material for almost 25 years and is considered as a pure electron conductor. Lack of ionic conductivity of the LSM leads to limitation of the overall reaction rate to the amount of triple phase boundary (TPB) where gaseous phase, electron-conducting phase and ion-conducting are in simultaneous contact. According to the literature it is optimal for the electrode material to be mixed in the 50:50 ratio with YSZ to increase the amount of the TPB. Thus, the active zone is extended further from the electrolyte surface into the volume of the electrode body. Even though the mixed electrode material exhibits great performance, information on the optimal thickness of the electrode is scarce in the literature. The electrode thickness is a crucial parameter since not all of the electrode volume is electrochemically active and represents just surplus resistance for the electric current impairing the overall electrode performance. The goal of our research is to determine of the extent of the active zone that we can estimate the optimal thickness of the LSM—YSZ electrode for various operation conditions.A macrohomogenous 1D model was developed to simulate the active electrode zone extent. Initial parametric study has shown that the extent of the active region of the electrode is influenced by many factors including the kinetics of the occurring reactions, the ionic and electronic conductivity of the respective domains and working conditions, such as temperature and operating current density. Even though the literature offers data on the conductivity of bulk the LSM and YSZ, the data of the respective conductivities in the LSM—YSZ are not applicable due to the electrode structure. The conductivity of the structure consisting of packed particles with a small contact area is limited by the contact resistance. This study targets to determine the electronic conductivity of the LSM phase and the ionic conductivity of the YSZ phase in the LSM—YSZ electrode framework.The LSM conductivity in the electrode framework was determined by resistance measurement of the casted layers of the LSM—YSZ using electrochemical impedance spectroscopy (EIS). The results show an exponential decrease of the LSM conductivity with decreasing LSM content. Furthermore, the 50:50 LSM—YSZ exhibits conductivity comparable to that of the bulk YSZ electrolyte. This result proves that the energy losses due to the electrical resistance of the LSM—YSZ electrode cannot be neglected in the terms of SOC performance.The determination of the ionic conductivity of YSZ in the electrode framework required the substitution of LSM with an inert material. The material of choice was CaSO4 due to its availability and its melting point being relatively close to that of the LSM. Similarly to the LSM, YSZ exhibited an exponential decrease of ionic conductivity with a decrease in YSZ volume fraction in the samples. Furthermore, the trend was compared to the Koh-Fortini relationship, showing that grain boundaries have a strong influence on the total conductivity of the material.The results of the experiments helped us to determine the extent of the active electrode zone leading to the estimation of optimal thickness of the LSM—YSZ oxygen electrode thickness.The authors acknowledge the financial support of the Czech Science Foundation (GACR), contract No: 19-142-44-J and by the Technology Agency of the Czech Republic under project no. TK04030143.

Rational design of mixed ionic–electronic conducting membranes for oxygen transport

The mixed ionic–electronic conducting (MIEC) oxides have generated significant research efforts in the scientific community during the last 40 years. Since then, many MIEC compounds, most of which are based on perovskite oxides, have been synthesized and characterized. These compounds, when heated to high temperatures, form solid ceramic membranes with high oxygen ionic and electrical conductivity. The driving force for oxygen ion transport is the ionic transfer of oxygen from the air as a result of the differential partial pressure of oxygen across the membrane. Electronic and ionic transport in a range of MIEC materials has been studied using the defect theory, particularly when dopants are introduced to the compound of interest. As a result, many types of ionic oxygen transport limits exist, each with a distinct phase shift depending on the temperature and partial pressure of oxygen in use. In combination with theoretical principles, this work attempts to evaluate the research community's major and meaningful achievements in this subject throughout the preceding four decades.

Microstructural Defects of Epoxy–Phenolic Polymers on Metal Substrates during Acidic Corrosion

This study uses confocal microscopy and image processing to investigate the microstructural changes of coating–metal systems immersed in a heated acidic bath. Unlike standard optical microscopy techniques, 3D confocal microscopy images can quantitatively reveal microscopic defects formed at early stages of cathodic delamination. The coatings are made of fluorescent epoxy–phenolic resins cured at high temperatures onto tinplate (T23) and tin-free steel (TFS) substrates. When the coated metal substrates are immersed in acetic acid, a series of microscopic corrosion events occur at the polymer–metal interface. These events are quantified by changes in the thickness distribution of the degraded samples relative to that of intact coatings. The degradation rate is highest for epoxy–phenolic polymers on TFS substrates, represented by multiple orders of magnitude increase in the number density of defect sites. Higher molecular weight coatings provide slightly better resistance against delamination. The coating thickness dictates the rate of oxygen diffusion and ion transport along the polymer–coating interface, where raised asperities serve as localized sites for metal oxidation and formation of alkaline species, leading to subsequent delamination of the cured polymers from the surfaces. The results show that the metal surface topology is as important as chemistry when designing the corrosion resistance of products containing acidic liquids, and that confocal microscopy is useful in quality control through early detection of mesoscale polymer failure.

Effect of inner strain on the performance of dual-phase oxygen permeable membranes

Inner strain appears in the dual-phase composites due to the different thermal expansion coefficients (TECs). For fluorite and perovskite epitaxial growing films, tensile and compressive strains can promote and inhibit the oxygen ionic transport, respectively. For oxygen permeable membranes, the oxygen ionic transport is closely related to the oxygen permeation flux. Therefore, the inner strain would affect the performance of fluorite-perovskite dual-phase membranes, however, that is still not disclosed. Herein, we found that the fluorite phase with low TECs is slightly stretched and the perovskite phase with high TECs is compressed in dual-phase membranes. The inner strain inhibits chemical expansion of perovskite phase by limiting the redox of B-site cations. Although the perovskite single-phase has the highest oxygen permeation flux, the oxygen permeation flux of dual-phase membranes decreases with increasing the content of perovskite phase. The unusual phenomenon is induced by the compressive strain on perovskite phase limiting the transport of oxygen ions. Therefore, in view of the vital role of inner strain to the chemical expansion and oxygen transport, it cannot be ignored during the design and mechanism discussion of oxygen permeable membranes. • Inner strain appears in the dual-phase membranes due to the different TECs. • The inner strain inhibits the chemical expansion of perovskite phase by limiting the redox of B-site cations. • Oxygen permeation flux decreases with increasing the content of perovskite phase due to the inner strain. • Inner strain limits the ionic conductivity of fluorite-perovskite dual-phase materials.

Advances in novel SDC@Al2O3 core−shell electrolyte for low‐temperature solid oxide fuel cell

AbstractThe preparation of electrolyte with excellent ionic conduction is an important development direction in the practical application of solid oxide fuel cell (SOFC). Traditional methods to improve ion conduction was structure doping to develop electrolyte materials. In this work, the ionic conductor Ce0.8Sm0.2O2‐δ (SDC) was modified by insulator Al2O3 to enhance ion conduction and apply as electrolytes for the SOFC. The transmission electron microscopy (TEM) characterization clearly clarified that a thin Al2O3 layer in the amorphous state coated on SDC to form the SDC@Al2O3 core−shell structure. The SDC@Al2O3 electrolyte with the core−shell structure possesses a super ionic conductivity of 0.096 S cm−1 and results in advanced cell performance of 1190 mW cm−2 at 550°C. The X‐ray photoelectron spectroscopy (XPS) analysis revealed that the concentration of oxygen vacancies in the SDC@Al2O3 core–shell structure significantly improved in comparison with pure SDC, the newly produced oxygen vacancies can promote the oxygen ion transport. Moreover, the interface between SDC and Al2O3 provides a fast channel for the proton transport. In addition, the SDC‐based SOFC was usually suffered from the reduction of the SDC electrolyte and the accompanying generated electron conduction should deteriorate the cell performance, this is the main challenge for the SDC electrolyte application. In our case, the Al2O3 shell on the SDC surface not only can avoid the contact between SDC and hydrogen to eliminate the reduction of SDC but also can restrain electron conduction due to the electron insulation characteristic of the Al2O3 shell. This work demonstrates an efficient approach to develop the advanced low‐temperature SOFC technology from material fundamentals.

An interesting application-oriented design of high-strength anode support for protonic ceramic fuel cells by a non-proton-conducting cermet

One key problem of protonic ceramic fuel cells (PCFCs) is insufficient mechanical strength of anode support. Herein, an interesting application-oriented design is to enhance the mechanical strength of PCFCs by using a non-proton-conducting cermet NiO-3mol%Y2O3–ZrO2 (3YSZ) based on the assumption that anode reactive thickness is relative limited. The flexural strength of NiO-3YSZ anode support can reach 210 MPa while that of NiO–BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) is only 58.5 MPa. Novel half-cells of NiO-3YSZ anode support, NiO-3YSZ-BZCYYb anode transition layer, NiO-BZCYYb anode functional layer and BZCYYb electrolyte layer are sequentially fabricated by tape-casting combined with the hot-pressing lamination. Fully integrated single cells can obtain a peak power density of 676 mW cm−2 at 700 °C and exhibit an acceptable long-term stability with the operation voltage of 0.75 V at 650 °C for 120 h with humid H2 as fuel and air as oxidation. Electrode polarization processes before and after the long-term stability test are further investigated by the relaxation time distribution method. The performance degradation is mainly related to the oxygen reduction reaction and oxygen ion transport processes on the cathode side, and there is little effect of the side reaction involved by Ni-3YSZ anode support.

Molecular dynamics study of oxygen-ion diffusion in yttria-stabilized zirconia grain boundaries

This work focuses on understanding the oxygen-ion transport through the mixed Grain Boundaries (GBs) present in yttria-stabilized zirconia (YSZ), a common solid oxide fuel cells (SOFCs) electrolyte.

Impact of Silica Additions on the Phase Composition and Electrical Transport Properties of Ruddlesden-Popper La2NiO4+δ Mixed Conducting Ceramics

The present work explores the possibility of incorporation of silicon into the crystal structure of Ruddlesden-Popper La2NiO4+δ mixed conducting ceramics with the aim to improve the chemical compatibility with lanthanum silicate-based solid electrolytes. Ceramics with the nominal composition La2Ni1−ySiyO4+δ (y = 0, 0.02 and 0.05) were prepared by the glycine nitrate combustion technique and sintered at 1450 °C. While minor changes in the lattice parameters of the tetragonal K2NiF4-type lattice may suggest incorporation of a small fraction of Si into the Ni sublattice, combined XRD and SEM/EDS studies indicate that this fraction is very limited (≪2 at.%, if any). Instead, additions of silica result in segregation of apatite-type La10−xSi6O26+δ and La2O3 secondary phases as confirmed experimentally and supported by the static lattice simulations. Both total electrical conductivity and oxygen-ionic transport in La2NiO4+δ ceramics are suppressed by silica additions. The preferential reactivity of silica with lanthanum oxide opens a possibility to improve the compatibility between lanthanum silicate-based solid electrolytes and La2NiO4+δ-based electrodes by appropriate surface modifications. The promising potential of this approach is supported by preliminary tests of electrodes infiltrated with lanthanum oxide.

Enhancing the Catalytic Activity and Coking Tolerance of the Perovskite Anode for Solid Oxide Fuel Cells through In Situ Exsolution of Co-Fe Nanoparticles

The in situ exsolved nanoparticles from the perovskite matrix have achieved increasing attention and wide applications in solid oxide fuel cells (SOFCs) due to their excellent stability and high catalytic activity. Herein, an A-site-deficient (Ba0.9La0.1)0.95Co0.7Fe0.2Nb0.1O3 – δ (BL95CFN) perovskite oxide with in situ exsolved Co-Fe nanoparticles is developed and investigated as an anode for SOFCs. Compared with stoichiometric BLCFN, a tiny A-site deficiency (5%) promoted the exsolution of cobalt and iron from the perovskite matrix of BL95CFN. This hybrid anode catalyst showed excellent electrochemical performance. The polarization resistance is 0.11 Ω cm2 for the BL95CFN anode at 750 °C, about 42% lower than that of the BLCFN anode. The maximum peak density (MPD) reaches 513.2 mW cm–2 at 750 °C for an electrolyte-supported single cell with the BL95CFN anode. The high electrochemical performance could be attributed to the accelerated hydrogen surface exchange process provided by exsolved Co-Fe nanoparticles and oxygen ion transport in the A-site-deficient perovskite matrix. High-resolution transmission electron microscope (HRTEM) reveals that exsolved Co-Fe nanoparticles are embedded in the oxide matrix, forming a firm anchoring structure, which ensures excellent anode coking tolerance. At the current density of 200 mA cm–2, the output voltage of the single cell remained stable within 200 h in methane fuel. Overall, the high catalytic activity and coking tolerance of the hybrid electrocatalyst manifest a bright prospect of application in SOFCs and electrolytic cells.

Nanocrystalline Surface Layer of WO3 for Enhanced Proton Transport during Fuel Cell Operation

High ionic conductivity in low-cost semiconductor oxides is essential to develop electrochemical energy devices for practical applications. These materials exhibit fast protonic or oxygen-ion transport in oxide materials by structural doping, but their application to solid oxide fuel cells (SOFCs) has remained a significant challenge. In this work, we have successfully synthesized nanostructured monoclinic WO3 through three steps: co-precipitation, hydrothermal, and dry freezing methods. The resulting WO3 exhibited good ionic conductivity of 6.12 × 10−2 S cm−1 and reached an excellent power density of 418 mW cm−2 at 550 °C using as an electrolyte in SOFC. To achieve such a high ionic conductivity and fuel cell performance without any doping contents was surprising, as there should not be any possibility of oxygen vacancies through the bulk structure for the ionic transport. Therefore, laterally we found that the surface layer of WO3 is reduced to oxygen-deficient when exposed to a reducing atmosphere and form WO3−δ/WO3 heterostructure, which reveals a unique ionic transport mechanism. Different microscopic and spectroscopic methods such as HR-TEM, SEM, EIS, Raman, UV-visible, XPS, and ESR spectroscopy were applied to investigate the structural, morphological, and electrochemical properties of WO3 electrolyte. The structural stability of the WO3 is explained by less dispersion between the valence and conduction bands of WO3−δ/WO3, which in turn could prevent current leakage in the fuel cell that is essential to reach high performance. This work provides some new insights for designing high-ion conducting electrolyte materials for energy storage and conversion devices.

Oxygen ionic transport in LaInO3 and LaIn0.5Zn0.5O2.75 perovskites: Theory and experiment

The new oxygen-deficient orthorhombic perovskite LaIn0.5Zn0.5O2.75 was obtained by solid-state synthesis. Ionic transport properties were studied by a combined theoretical approach consisting of geometrical-topological analysis, bond valence site energy modeling and density functional theory (DFT) calculations. The DFT calculations showed that oxygen migration energy is by 0.2 eV lower for zinc-containing perovskite compared to pure LaInO3. The conductivity was measured in the temperature range of 400–1000 °C and at various oxygen partial pressures 10−18–2·10−1 atm. LaIn0.5Zn0.5O2.75 was found to be pure oxide-ion conductor (σ ≈ 10−5 S/cm) at T < 550 °C in air with the experimental ionic activation energy of 0.79 eV compared to 0.97 eV for LaInO3, which is in agreement with our theoretical prediction. With increasing the temperature the share of the hole conductivity of LaIn0.5Zn0.5O2.75 increased.

Resistance Switching and Failure Behavior of the MoOx/Mo2C Heterostructure.

With the rapid demand for high-performance and power-efficient memristive and synaptic systems, more 2D heterostructures with improved resistance switching (RS) properties are still urgently in need for next-generation devices. Here, we report the RS behaviors of vertical MoOx/Mo2C heterostructures fabricated by controllable thermal oxidation and uncover the failure behavior for the first time. It is found that the MoOx/Mo2C heterostructure exhibits bipolar RS with a low set/reset voltage of +0.5/-0.3 V, an ultralow power consumption of 5 × 10-8 W, and an on/off ratio of 102, which is ascribed to the transport of the internal oxygen ions of MoOx. Furthermore, the failure behavior of RS behaviors of the MoOx/Mo2C heterostructure under a higher work voltage is revealed. It indicates that the amorphization of the pristine crystalline MoOx layer could block the movement of the internal oxygen ions in the vertical direction. The excellent RS performance induced by the synergy of MoOx and Mo2C and the demonstration of the failure behavior enable the potential applications of the 2D heterostructure in related memory devices and biological neural networks.

Mixed ionic-electronic conducting composite-based ceramic-carbonate dense membranes for CO2/O2 counter-permeation and CO oxidation

Dense inorganic membranes made of the ionic conductor Ce0.80Sm0.15Sr0.05O2-δ and the electronic-ionic conductor Sm0.6Sr0.4Al0.3Fe0.7O3-γ were infiltrated with molten carbonates. One side of the membrane is supplied with CO, and the opposite side is fed with O2. The CO oxidation and CO2/O2 counter-permeation fluxes are studied as functions of temperature and weight percent of the mixed ionic-electronic conductor phase. The O2 counter-permeation was correlated to the oxygen ionic flux counter-permeation consumed for CO oxidation and CO32− formation for CO2 permeation. The Ce0.80Sm0.15Sr0.05O2-δ/Sm0.6Sr0.4Al0.3Fe0.7O3-molten carbonates system exhibits higher oxygen ionic flux counter-permeation than Ce0.80Sm0.15Sr0.05O2-δ-molten carbonates system, producing a larger amount of CO conversion in the first case. The limiting factor for the O2 counter-permeation and CO2 permeation in triple-phase membranes is the oxygen ionic conductivity. In dual-phase membranes, the redox reaction for oxygen dissociation becomes vital for oxygen ionic flux. However, the limiting factor for the O2 permeation flux is the oxygen ionic transport in the ceramic phase. On other hand, the limiting factor for the CO2 permeation is attributed to both the ionic transport in the molten carbonates and the ceramic phase. The weight percent of the perovskite Sm0.6Sr0.4Al0.3Fe0.7O3 was varied to study the effect of its electronic property on the CO2/O2 counter-permeation flux and CO oxidation, establishing that the electronic nature of Sm0.6Sr0.4Al0.3Fe0.7O3 enhances the formation of oxygen ions. This increases the carbonate ions concentration on the surface of the CO-supply membrane side, which raises the driving force for CO2 permeation. Also, the CO2 formation rate on the oxygen supply side is faster than on the CO-supply membrane side. The formation rate of molecular oxygen is lower than the CO2 formation rate.

A High Performance La0.2Sr0.8Co0.8Fe0.2O3-δ Catalyst As an Oxygen Electrode for Reversible Solid Oxide Cells at Intermediate Temperature

Solid oxide cells (SOCs) have been reported as promising energy production and storage devices due to their high efficiency and low pollutant emissions. A key barrier to achieve high performance of SOCs is high electrode polarization resistance which attributes to the sluggish kinetics of oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) at reduced temperatures. One of the potential oxygen electrodes is a perovskite La0.6Sr0.4Co0.2Fe0.8O3- δ(LSCF6428) with mixed ionic and electronic conduction (MIEC) because of its considerable conductivities and good chemical compatibility with conventional electrolyte materials such as ceria-based oxides. However, upon long-term operation under fuel cell conditions, the LSCF6428 electrode is usually subjected to severe degradation of ORR kinetics owing to chemical instability. It has been well known that the tailoring the chemical composition of the perovskite material strongly modulates their electrochemical activities and oxygen ion transport properties.In this study, we synthesized the La0.2Sr0.8Co0.8Fe0.2O3- δ (LSCF2882) and systematically investigated its characteristics on intrinsic properties. In addition, we evaluated oxygen transport kinetics and electrochemical performance of LSCF2882 as an oxygen electrode for reversible SOC applications.

Composite of calcium cobaltite with praseodymium-doped ceria: A promising new oxygen electrode for solid oxide cells

Calcium cobaltites have emerged as an attractive alternative to be used in Solid Oxide Cells (SOCs), due to their excellent thermal compatibility with standard electrolytes that may privilege these compounds among state-of-the-art SOC electrodes. Nonetheless, their electrochemical performances have been strongly limited by poor oxygen ion transport. Hence, we report a new composite electrode containing the misfit calcium cobaltite [Ca2CoO3-δ]0.62[CoO2] (C349) phase combined with Ce0.8Pr0.2O2-δ (CPO). A comparative study is presented between this composite and the standard La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), in terms of their microstructures, number of depositions, and resultant electrochemical properties. Such tailoring permits the best C349/CPO composite electrode to attain high levels of electrochemical performance that rival with the standard LSCF material. This successful result is highly relevant, as it can provide insight into the most critical optimisation factors for similar SOC electrodes that intrinsically suffer from similarly low levels of ionic transport.

High-Performance Perovskite Composite Electrocatalysts Enabled by Controllable Interface Engineering.

Single-phase perovskite oxides that contain nonprecious metals have long been pursued as candidates for catalyzing the oxygen evolution reaction, but their catalytic activity cannot meet the requirements for practical electrochemical energy conversion technologies. Here a cation deficiency-promoted phase separation strategy to design perovskite-based composites with significantly enhanced water oxidation kinetics compared to single-phase counterparts is reported. These composites, self-assembled from perovskite precursors, comprise strongly interacting perovskite and related phases, whose structure, composition, and concentration can be accurately controlled by tailoring the stoichiometry of the precursors. The composite catalyst with optimized phase composition and concentration outperforms known perovskite oxide systems and state-of-the-art catalysts by 1-3 orders of magnitude. It is further demonstrated that the strong interfacial interaction of the composite catalysts plays a key role in promoting oxygen ionic transport to boost the lattice-oxygen participated water oxidation. These results suggest a simple and viable approach to developing high-performance, perovskite-based composite catalysts for electrochemical energy conversion.

Achieving Highly Efficient Carbon Dioxide Electrolysis by In Situ Construction of the Heterostructure.

The design of active cathode catalysts, with abundant active sites and outstanding catalytic activity for CO2 electroreduction, is important to promote the development of solid oxide electrolysis cells (SOECs). Herein, A-site-deficient perovskite oxide (La0.2Sr0.8)0.9Ti0.5Mn0.4Cu0.1O3-δ (LSTMC) is synthesized and studied as a promising cathode for SOECs. Cu nanoparticles can be rapidly and uniformly in situ-exsolved under reducing conditions. The heterostructure formed by the exsoluted Cu and LSTMC provides abundant active sites for the catalytic conversion of CO2 to CO. Combined with the remarkable oxygen-ion transport capacity of the LSTMC substrate, the specially designed Cu@LSTMC cathode exhibits a dramatically improved electrochemical performance. Furthermore, first-principles calculations proposed a mechanism for the adsorption and activation of CO2 by the heterostructure. Electrochemically, the Cu@LSTMC presents a high current density of 2.82 A cm-2 at 1.8 V and 800 °C, which is about 2.5 times higher than that of LSTM (1.09A cm-2).

Decyltriphenylphosphonium bromide containing hydrophobic alkyl-chain as a potential corrosion inhibitor for mild steel in sulfuric acid: Theoretical and experimental studies

A triphenylphosphonium based ionic liquid containing a long hydrophobic alkyl-chain (designated as DTPPB) was evaluated as a potential corrosion inhibitor for mild steel (MS) in 0.5 M H2SO4 solution. Inhibition efficiency and adsorption behavior of DTPPB was determined by performing the experimental analyses were carried out at the different concentration and temperature. Corrosion inhibition effectiveness of DTPPB was determined experimentally using electrochemical and surface analyses (SEM-EDX and AFM). Polarization studies showed that DTPPB acted as a mixed-type inhibitor. Inhibition effectiveness of DTPPB increases with increasing its concentration. The potentiostatic polarization study revealed that passivation was perceived at lower DTPPB concentrations. The Nyquist plot of impedance is expressed mainly as a depressed capacitive loop with different concentrations. Self-organization of the chains and tail groups to form a coherent hydrophobic film that serves as a barrier for the transport of water, oxygen, and corrosive ions to the metal surface. In addition to the electrochemical studies, surface morphology analyses provided strong evidence for the existence of inhibitor film over the MS surface and their results were supported by the computational data.

Inhibiting in situ phase transition in Ruddlesden-Popper perovskite via tailoring bond hybridization and its application in oxygen permeation

Inhibiting in situ phase transition in Ruddlesden-Popper perovskite via tailoring bond hybridization and its application in oxygen permeation