Gadolinium-doped Cerium Oxide Research Articles

Oxygen transport mechanism and the effect of microstructure on the oxygen response behavior of an oxygen-sensitive composite Ce0.9Gd0.1O2-ẟ – La0.6Sr0.4FeO3-ẟ at high temperature

Compositions like gadolinium doped cerium oxide Ce0.9Gd0.1O2-ẟ and strontium doped lanthanum ferrite La0.6Sr0.4FeO3-ẟ, or their composites are well known in the field of fuel cell electrolyte, oxygen transporting membrane and catalytic reactor applications. This work offers insight into composite material's oxygen response characteristics, taking Ce0.9Gd0.1O2-ẟ and La0.6Sr0.4FeO3-ẟ in 70: 30 wt percent. One pot sol-gel method was employed for the powder synthesis. The powder was characterized by TG-DSC, XRD, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). FESEM-EDX and EDX-line profiling techniques were used to check the compositional homogeneity of sintered bodies. Oxygen response tests were conducted from ambient (20 % O2) to 100 % O2 concentration, using bulk samples sintered at three different temperatures, i.e., 1000, 1150, and 1250 °C at a fixed soaking time of 4 hours. The sintered specimens' apparent porosity, bulk density, surface morphology, and electrical conductivity were also examined. The sintering temperature significantly impacts response behavior as the porosity and grain size of the sintered body plays a vital role in sensing performance. The mechanism of response towards oxygen is also discussed. Sample 73–100 displayed the best performance among others. We achieved the lowest response and recovery time of 15 – 48 sec and 45 – 80 sec from a 0.60 mm thick bulk material at 950 °C. Harsh environments were intentionally created to check the reliability and reproducibility of the response data. This material could be a good candidate as an oxygen gas sensor at high temperatures owing to its good sensitivity, reliability, reversibility, and stability.

Development and investigation of a porous metal-ceramic substrate for solid oxide fuel cells

The process of creating a porous metal-ceramic material based on Ni-Al alloy and gadolinium-doped cerium oxide (CGO) using the thermal explosion method has been investigated. This study aims to analyze the effect of CGO on the thermal explosion parameters and the architecture of the resulting Ni-Al-CGO materials. In this regard, the influence of adding CGO powder to the Ni-Al system on the synthesis process and structure formation during controlled heat loss thermal explosion has been studied. Dependencies of temperature and time characteristics of the thermal explosion on initial parameters have been measured. It has been demonstrated that the concentration of CGO in the initial mixture and heat dissipation from the sample significantly affect the rate of the exothermic reaction. The phase composition of the obtained porous materials, depending on the CGO content and the temperature of subsequent vacuum annealing, was analyzed using X-ray diffraction. The chemical composition and microstructure of the synthesis products were examined through electron microscopy and energy-dispersive X-ray spectroscopy. The possibility of forming metal-ceramic composites with a porosity of 60–65 % for use as supporting substrates for solid oxide fuel cells with a NiO/CGO anode has been shown. An anodic layer of NiO/CGO was applied to a metal-ceramic base of the composition (Ni+25 %Al)+5 %CGO using screen printing, which was then annealed in an air atmosphere at 1300 °C and reduced at 900 °C in a hydrogen atmosphere. The dilatometric method determined that adding 40 wt.% Cr to a mixture of Ni-Al powders reduces the average coefficient of thermal expansion of the new material.

Synthesis, microstructural and optical characterizations of sol-gel grown gadolinium doped cerium oxide ceramics.

In this study, through the utilization of the sol-gel combustion tactic, gadolinium (Gd)-doped cerium oxide (CeO2), Ce1-xGdxO2 (x = 0.00, 0.10, 0.20 and 0.30 (GDC)) ceramics were attained. The synthesized GDC ceramics were investigated using X-ray diffraction (XRD) to scrutinize their crystal structures and phase clarities. The obtained GDC ceramics have a single-phase cubic structure and belong to the crystallographic space group fm3̄m (225). The measurement of the diffraction angle of each reflection and the subsequent smearing of the renowned Bragg's relation provided coarse d-interplanar spacings. The stacking fault (SF) values of pure and Gd-doped CeO2 ceramics were assessed. To muse the degree of preferred orientation (σ) of crystallites along a crystal plane (h k l), the texture coefficient (Ci) of each XRD peak of GDC ceramics is gauged. By determining the interplanar distance (dh k l), the Bravais theory sheds light on the material's development. By exploiting Miller indices for the prime (1 1 1) plane, the lattice constants of GDC ceramics and cell volumes were obtained. Multiple techniques were employed to ascertain the microstructural parameters of GDC ceramics. A pyrometer substantiated the density of GDC ceramics. The room temperature (RT) Fourier transform infrared (FTIR) spectra of both un-doped and Gd-doped CeO2 were obtained. The UV-vis-NIR spectrometer recorded the GDC ceramics' reflectance (R) spectra at RT. For both undoped and Gd-doped CeO2, the absorption coefficient (α) spectra showed two distinct peaks. The R-dependent refractive index (η) and the α-dependent extinction coefficient (k) were determined for all GDC samples. The optical band gap (Eg) was obtained by integrating the Tauc and Kubelka-Munk approaches for GDC ceramics. For each GDC sample, the imaginary (εi) and real (εr) dielectric constants, as well as the dissipation factor (tan δ), were determined local to the characteristic wavelength (λc). Calculations were made for the Urbach energy (EU) and Urbach absorption coefficient (α0) for GDC ceramics. The minimum and maximum values of optical (σo) and electrical (σe) conductivity for GDC ceramics were determined. The volume (VELF) and surface (SELF) energy loss functions, which depend on the constants εi and εr, were used to measure electrons' energy loss rates as they travel across the surface. Raman spectroscopy revealed various vibrational modes in GDC ceramics. Finally, the implications are discussed herein.

Enhanced electrochemical performance of SOFC: GDC electrolyte grains encapsulation via DZSB film

The fluorite-structured oxygen ion conductor gadolinium-doped cerium oxide (GDC) is preferred as an electrolyte for low- and medium-temperature solid oxide fuel cells over yttria-stabilized zirconia (YSZ). However, GDC requires a higher sintering temperature which limits its application. To decrease its sintering temperature and enhance its conductivity at low and medium temperatures, a novel (Dy0.20Zr0.05Bi0.75)2O3-δ - Gd0.10Ce0.90O2-δ (xDZSB-GDC, x = 1,2,3,4,5, and10 wt%) nanocomposite is designed and prepared by solid-phase method. Microstructure and electrochemical characteristics of the DZSB-GDC composite are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and alternating current (AC) impedance spectroscopy. DZSB effectively promotes the densification of the GDC electrolyte and reduces GDC's grain-boundary impedance. Theuniform distribution of DZSB around the GDC interface provided channels for ion transfer. Compared to the GDC electrolyte (1.30 × 10−3 S cm−1), the conductivity of 10 DZSB-GDC is six times higher at 550 °C (8.30 × 10−3 S cm−1). DZSB at low oxygen partial pressure efficiently inhibits the electronic conduction of GDC and boosts the open-circuit voltage of the single cell. At 750 °C, the maximum output power of a 10DZSB-GDC electrolyte-supported single cell is 364 mWcm−2, greater than 1.75 times the power density of a GDC-supported cell. These findings indicate thatDZSB-GDC is a promising electrolyte material for solid oxide fuel cells.

Optical, magnetic, and electrochemical properties of a fluorite-perovskite Ce0.9Gd0.1O2-∂ - La0.6Sr0.4FeO3-∂ nanocomposite synthesized by one pot sol-gel auto-combustion route

Gadolinium-doped cerium oxide (Ce0.9Gd0.1O2-∂; CGO) and strontium-doped lanthanum ferrite (La0.6Sr0.4FeO3; LSF) are well-known compounds for their application in solid oxide fuel cells, dense oxygen permeable membrane, and high-temperature ceramic reactor. The superior electro-catalytic performance of these two individual oxides or their composites is well established as it originates from multivalent cations (Ce3+/4+ and Fe2+/3+/4+) and doping-induced defects like electrons, holes, and oxygen vacancies. This work focuses on synthesizing and characterizing composite taking CGO and LSF in different weight ratios, i.e., 10:90, 30:70, 50:50, 70:30, and 90:10 by sol-gel auto-combustion process. End members CGO and LSF were also synthesized for comparison purposes. All synthesized nanopowders (single phases and their composites) were characterized with X-ray diffraction (XRD) for phase identification and Scanning electron microscopy (SEM) for elemental composition analysis. XRD and SEM results established the formation of the required phase and targeted composition. The optical properties of the materials were evaluated with the help of ultraviolet–visible Diffuse Reflectance Spectroscopy (UV–Vis DRS). Tauc's approximation measured band gap energies, and all the composites showed a very high band gap in the 4.85–5 eV range. Magnetic properties such as saturation magnetization (Ms), remanence (Mr), and coercive force (Hc) were calculated from a magnetic hysteresis loop obtained from the Vibrating-sample magnetometer (VSM) experiment at room temperature. Furthermore, the law of approach to saturation (LAS) model was applied to more precisely calculate Ms and other essential parameters. In magnetic characterization, the LSF phase fraction controls the overall magnetic property of the composites. Electrochemical behavior, such as the composites' charge storage ability and stability were tested by cyclic voltammetry and chronopotentiometry method. All the samples exhibited good stability, and the highest specific capacitance of 26 F/gm was obtained for the composite sample (CL91) when only 10 % LSF phase was incorporated in the nanocomposite.

Aligned nanofibers incorporated composite solid electrolyte for high-sensitivity oxygen sensing at medium temperatures

Potentiometric oxygen sensors have been widely used in internal combustion engines, industrial boilers, and metallurgical heat treatment furnaces. However, traditional oxygen sensors based on yttria-stabilized zirconia (YSZ) electrolyte can only be operated at elevated temperatures (> 750 °C) due to their relatively low ionic conductivity. In this study, we present a highly efficient micro-oxygen sensor that can be operated at a temperature as low as 300 °C. This micro-oxygen sensor incorporates a composite solid electrolyte, i.e., well-aligned gadolinium-doped cerium oxide (CGO) nanofibers embedded within a YSZ matrix (YSZ/CGOf). The arrays of CGO nanofibers in the YSZ matrix are parallel to the conduction direction, providing rapid conducting channels for oxygen ions. Benefitting from this design, the composite electrolyte leads to a conductivity of four times higher than that of traditional YSZ solid electrolytes at low temperatures. This enhancement in conductivity is attributed to the presence of a defective interfacial region between CGOf and YSZ, which promotes the mobility of oxygen ions. The strategy of constructing fast ionic conduction in the composite electrolyte by using well-aligned nanofibers may be considered for the design and optimization of other micro/nano-devices including sensors, batteries, and fuel cells.

Hybrid Polyelectrolyte Capsules Loaded with Gadolinium-Doped Cerium Oxide Nanoparticles as a Biocompatible MRI Agent for Theranostic Applications.

Layer-by-layer (LbL) self-assembled polyelectrolyte capsules have demonstrated their unique advantages and capability in drug delivery applications. These ordered micro/nanostructures are also promising candidates as imaging contrast agents for diagnostic and theranostic applications. Magnetic resonance imaging (MRI), one of the most powerful clinical imaging modalities, is moving forward to the molecular imaging field and requires advanced imaging probes. This paper reports on a new design of MRI-visible LbL capsules, loaded with redox-active gadolinium-doped cerium oxide nanoparticles (CeGdO2-x NPs). CeGdO2-x NPs possess an ultrasmall size, high colloidal stability, and pronounced antioxidant properties. A comprehensive analysis of LbL capsules by TEM, SEM, LCSM, and EDX techniques was carried out. The research demonstrated a high level of biocompatibility and cellular uptake efficiency of CeGdO2-x-loaded capsules by cancer (human osteosarcoma and adenocarcinoma) cells and normal (human mesenchymal stem) cells. The LbL-based delivery platform can also be used for other imaging modalities and theranostic applications.

Shape-Controlled Ni Supported GDC Catalyst and its Application in Direct Ethanol Solid Oxide Fuel Cells

Matching catalytic activity with the high temperature heat treatments required to process solid oxide fuel cells (SOFCs) can be a challenge. Shape control is an interesting strategy to stabilize the surface of nanoparticles during heat treatments. In this study, nickel-based catalysts supported on shape-controlled (nanorods and nanocubes) gadolinium-doped cerium oxide (GDC) were evaluated for direct ethanol SOFCs. The morphology of the support had a significant effect on the catalytic activity. It was shown that the Ni catalyst supported on the GDC nanorods maintained high catalytic activity after heat treatments for catalytic layer sintering. Such catalyst was applied as catalytic layer on a SOFC operating directly on anhydrous ethanol at 700 °C. The fuel cell operated for more than 100 h under 0.6 V displaying consistent performance with no indication of degradation from carbon deposition.

Two-dimensional gadolinium-doped ceria nanosheets for low temperature sintering of solid oxide fuel cells barrier layer

A novel method for bottom-up synthesis of two-dimensional (2D) gadolinium-doped cerium oxide (CGO) nanosheets is developed and demonstrated as an efficient precursor for interdiffusion barrier layer deposition in solid oxide fuel cells. The CGO is the standard material used as an interlayer in intermediate-temperature solid oxide fuel cells to avoid undesirable reactions between lanthanum strontium cobalt ferrite (LSCF) cathode and yttria-stabilized zirconia (YSZ) electrolyte materials. Herein, the shape-control of the 2D CGO by a low-cost wet-chemical method allowing for the fabrication of fully dense barrier layer of CGO is reported. The high surface coverage promoted by the 2D CGO nanosheets resulted in a thin (∼ 1 µm) and dense interdiffusion barrier layer sintered at 1150 °C preventing the undesirable reaction between oxide ion conducting phases occurring at higher temperatures. The electrochemical properties of solid oxide fuel cells confirmed the CGO nanosheet as an efficient layer for preventing the formation of resistive phases at the electrolyte/cathode interface.

Shape-Controlled Ni Supported GDC Catalyst and its Application in Direct Ethanol Solid Oxide Fuel Cells

Matching catalytic activity with the high temperature heat treatments required to process solid oxide fuel cells (SOFCs) can be a challenge. Shape control is an interesting strategy to stabilize the surface of nanoparticles during heat treatments. In this study, nickel-based catalysts supported on shape-controlled (nanorods and nanocubes) gadolinium-doped cerium oxide (GDC) were evaluated for direct ethanol SOFCs. The morphology of the support had a significant effect on the catalytic activity. It was shown that the Ni catalyst supported on the GDC nanorods maintained high catalytic activity after heat treatments for catalytic layer sintering. Such catalyst was applied as a catalytic layer on a SOFC operating directly on anhydrous ethanol at 700 °C. The fuel cell operated for more than 100 h under 0.6 V displaying consistent performance with no indication of degradation from carbon deposition.

Heavily Gd-Doped Non-Toxic Cerium Oxide Nanoparticles for MRI Labelling of Stem Cells.

Recently, human mesenchymal stem cells (hMSc) have attracted a great deal of attention as potential therapeutic agents in the treatment of socially significant diseases. Despite substantial advances in stem-cell therapy, the biological mechanisms of hMSc action after transplantation remain unclear. The use of magnetic resonance imaging (MRI) as a non-invasive method for tracking stem cells in the body is very important for analysing their distribution in tissues and organs, as well as for ensuring control of their lifetime after injection. Herein, detailed experimental data are reported on the biocompatibility towards hMSc of heavily gadolinium-doped cerium oxide nanoparticles (Ce0.8Gd0.2O2-x) synthesised using two synthetic protocols. The relaxivity of the nanoparticles was measured in a magnetic field range from 1 mT to 16.4 T. The relaxivity values (r1 = 11 ± 1.2 mM-1 s-1 and r1 = 7 ± 1.2 mM-1 s-1 in magnetic fields typical of 1.5 and 3 T MRI scanners, respectively) are considerably higher than those of the commercial Omniscan MRI contrast agent. The low toxicity of gadolinium-doped ceria nanoparticles to hMSc enables their use as an effective theranostic tool with improved MRI-contrasting properties.

Stable Ce0.8Gd0.2O2-δ oxygen transport membrane reactor for hydrogen production

Hydrogen production using oxygen transport membrane reactors has attracted widespread attention. However, the structural stability of membrane materials under harsh reducing atmospheres is still a significant challenge. Gadolinium doped cerium oxide (CGO) presents high ionic conductivity and good reducing resistance but is limited by its poor electronic conductivity. Herein, a 2 mol.% cobalt-doped Ce0.8Gd0.2O2-δ (CoCGO) ultrathin membrane was manufactured by thin-film technology and applied to hydrogen production from water splitting (WS) with simultaneous syngas production through partial oxidation of methane (POM). Two catalysts, La0.4Sr0.6CoO3-δ (LSC) and Ni/Al2O3, were utilized for promoting WS and POM, respectively. Hydrogen production rate above 1.8 mL min-1 cm-2 and methane conversion of around 80 % were achieved, and no noticeable degradation was detected during 100 h operation, suggesting its prospective stability advantages as a membrane reactor for hydrogen production from water.

Oxide film constricts under an electric field

Researchers have discovered a new way to engineer thin films that change volume under an electric field. Their technique could help scientists create small, energy-efficient biomedical devices ( Nature 2022, DOI: 10.1038/s41586-022-05073-6 ). Electrostrictive materials generate strain in response to an electric field. Researchers are interested in harnessing this property, measured by a material’s electrostriction coefficient, to build low-power biomedical devices such as microsensors. But many of the highest-performing electrostrictors contain lead, which can be toxic. Recently, scientists discovered electrostriction properties in gadolinium-doped cerium oxide (CGO), which is used in solid oxide fuel cells. Materials scientists Haiwu Zhang, Nini Pryds, and Vincenzo Esposito of the Technical University of Denmark wanted to know if they could improve its performance. They started by depositing alternating layers of CGO and erbium-stabilized bismuth oxide onto a neodymium gallate substrate, making multilayer films about 17 nm thick. Chemical defects in the oxide layers create local

Effect of Radial Stress on the Nanoparticle-Based Electrolyte Layer in a Center-Wound Roll with Roll-to-Roll Systems.

Recently, slot-die coating based on the roll-to-roll process has been actively used to fabricate nanoparticle-based electrolyte layers because it is advantageous for high-speed processes and mass production of uniformly thick electrolyte layers. In this process, the fabricated electrolyte layer is stored as a wound roll throughout the rewinding process. We analyzed the defects and geometric changes in an electrolyte layer, i.e., gadolinium-doped cerium oxide (GDC), due to the radial stress in the wound roll. We found that the thickness of the coated layer could be decreased by increasing the radial stress, i.e., cracks can be generated in the coated layer if excessively high radial stress is applied to the wound-coated layer. More thickness changes and crack defects were generated with time due to the residual stress in the wound roll. Finally, we analyzed the effects of taper tension profiles on the defects of the coated layer in the wound roll and determined the taper tension profile to minimize defects.

Strongly coupled oxygen reservoir enabled highly efficient solid oxide fuel cell cathode operation under harsh conditions

The field distribution of oxygen concentration in cathode areas in planar type solid oxide fuel cell stack seriously affects power output, especially at the outlet of/beneath the interconnector where oxygen supply suffers from shortage. A new in-situ solvothermal growth method is applied to prepare gadolinium doped cerium oxide (GDC) nano particles decorated lanthanum strontium cobalt ferrite (LSCF) heterostructure cathode (LSCF@GDC) which performed well under a wide oxygen partial pressure range (0.03–0.21 atm). The cathode shows enhanced specific surface area and improved sintering activity, yielding stronger cathode/electrolyte interface contact. Specifically, the cell equipped with LSCF@GDC cathode demonstrates 40-fold promoted performance under low oxygen partial pressures ( p O 2 = 0.03 a t m ) e.g. 0.415 W/cm 2 for LSCF@GDC versus 0.0107 W/cm 2 for bare LSCF at 750 °C. The systematic characterizations verify that the strong coupling effect between GDC and LSCF, i.e., the GDC serves as the oxygen reservoir to not only alter the crystal structure of LSCF with enhanced oxygen content, but also guarantee sufficient oxygen species for LSCF under oxygen-starving atmosphere. Simultaneously, the oxygen-abundant cathode surface and optimized interface are considered to collectively contribute to the improved electrochemical performances and enable efficient operation. • LSCF@GDC heterostructure cathode is constructed via solvothermal method. • SOFC performance improvement by 40-fold under oxygen partial pressure of 0.03 atm. • Oxygen reservoir effect due to surface anchored GDC nano particles is verified.

Effect of precursor powder uniformity on structure and electrical properties of gadolinium-doped cerium oxide ceramics

The effects of precursor powder uniformity on structure and electrical properties of Gd-doped CeO2 (GDC) electrolytes were studied. The as-synthesized GDCx powders (x = 5, 10 and 15 at.%) were calcined at 600 and 1200?C and combined in mass ratios of 100:0 and 95:5 to obtain two precursor powders with different particle size distributions. Sintering of the pressed pellets was performed at 1300 and 1400?C for 10 h. Crystal structure, microstructure and electrical properties of the samples were investigated by X-ray diffraction, scanning electron microscopy and AC impedance spectroscopy, respectively. When a smaller proportion of large particles (calcined at 1200 ?C) were present in the precursor powders, sinterability of the prepared samples is slowed down, which had an adverse effect on electrical conductivity. The lower the concentration of Gd, the more significant is the adverse effect. At higher sintering temperature (1400?C), the influence of Gd concentration on microstructure and ionic conductivity is more obvious. The GDC15 sample, prepared from the precursor powder calcined at 600?C, had the highest conductivity and ?asGB/?Bulk ratio at 300?C.

Conductivity and microstructural evaluation of SGDC solid electrolytes synthetized by Pechini and controlled precipitation

In this work, controlled precipitation synthesis methods and polymeric precursors (Pechini) were used to obtain gadolinium-doped cerium oxide solid electrolytes (Ce0.8Gd0.2O1.9) and double-doped cerium oxide with gadolinium and samarium (Ce0.8Gd0.2−xSmxO1.9x=0.01; 0.03 and 0.05). The main results indicate that the synthesized powders by the Pechini method present better microstructural characteristics such as larger specific surface area and smaller particle size. Test specimens were compacted (187MPa) and sintered (1500°C/6h) and subsequently characterized. Through the impedance spectroscopy analysis, an increase in the percentage of the samaria caused an increase in the grain boundary and grain conductivity in all the samples under study. In the grain interior, samples without samaria showed heterogeneous regions, where the cation-vacancy pairs are tightly bound, precluding these vacancies from participating in ion conduction. In the samples with samaria, these defect groups are smaller, indicating structural homogeneity, resulting in greater ionic conductivity. Grain boundary specific conductivities show slight increase for samples codoped with samarium oxide. This effect suggests that Sm3+ additions change the charge equilibrium in space-charge layer favoring better dopant distribution.

Biocompatible dextran-coated gadolinium-doped cerium oxide nanoparticles as MRI contrast agents with high T1 relaxivity and selective cytotoxicity to cancer cells.

Gd-based complexes are widely used as magnetic resonance imaging (MRI) contrast agents. The safety of previously approved contrast agents is questionable and is being re-assessed. The main causes of concern are possible gadolinium deposition in the brain and the development of systemic nephrogenic fibrosis after repeated use of MRI contrasts. Thus, there is an urgent need to develop a new generation of MRI contrasts that are safe and that have high selectivity in tissue accumulation with improved local contrast. Here, we report on a new type of theranostic MRI contrast, namely dextran stabilised, gadolinium doped cerium dioxide nanoparticles. These ultra-small (4-6 nm) Ce0.9Gd0.1O1.95 nanoparticles have been shown to possess excellent colloidal stability and high r1-relaxivity (3.6 mM-1 s-1). They are effectively internalised by human normal and cancer cells and demonstrate dose-dependent selective cytotoxicity to cancer cells.

High performance and carbon-deposition resistance metal-supported solid oxide fuel cell with a nickel–manganese spinel modified anode

To achieve high performance and carbon-deposition resistance, solid oxide fuel cells (SOFCs) with a nickel-10 wt% iron alloy support, a 10 wt% gadolinium doped cerium oxide electrolyte (GDC), a La0.6Sr0.4Co0.2Fe0.8O3-GDC (LSCF-GDC) cathode, and a Ni-GDC anode with (modified anode cell, MAC) or without (conventional anode cell, CAC) NiMn2O4 modification are prepared and evaluated with H2 and CH4 fuels. During the cell fabrication, the GDC in the anode of MAC is doped by Mn and Fe through reaction with NiMn2O4 and Fe diffusion from the support with increased electrical conductivity and catalytic activity; and the Ni granules in the anode is decorated with fine MnO particles, which increases their porosity and resistance to agglomeration and carbon deposition. As a result, MAC demonstrates higher performance and durability than CAC, with a maximum power density of 1278 and 1208 mW cm−2 at 700 °C with H2 and CH4 as the fuel, respectively, in contrast to 998 and 895 mW cm−2 for CAC. And the cell voltage of MAC fueled by CH4 is maintained on the level of 0.66 V for up to 100 h at 650 °C without carbon deposition in the anode, while that of CAC decreases continuously with significant carbon formation.

Carbonate dual-phase improves the performance of single-layer fuel cell made from mixed ionic and semiconductor composite

A mixed ionic and semiconducting composite in a single-layer configuration has been shown to work as a fuel cell at a lower temperature (500–600 °C) than a traditional solid-oxide fuel cell. The performance of a single-layer fuel cell (SLFC) is often limited by high resistive losses. Here, a eutectic mixture of alkali-carbonates was added to SLFC to improve the ionic conductivity. The dual-phase composite ionic conductor consisted of a ternary carbonate (sodium lithium potassium carbonate, NLKC) mixed with gadolinium-doped cerium oxide (GDC). Lithium nickel zinc oxide (LNZ) was used as the semiconducting material. The LNZ-GDC-NLKC SLFC reached a high power density, 582 mW/cm2 (conductivity 0.22 S/cm) at 600 °C, which is 30 times better than without the carbonate. The best results were obtained with the ternary carbonate which decreased the ohmic losses of the cell by more than 95%, whereas the SLFC with a binary carbonate (sodium lithium carbonate, NLC) showed a lower conductivity and performance (243 mW/cm2, 0.17 S/cm at 600 °C). It is concluded that adding carbonates to LNZ-GDC will improve the ionic conductivity and positively contribute to the cell performance. These results suggest a potential path for further development of SLFCs, but also imply the need for efforts on up-scaling and stability to produce practical applications with SLFC.