As a cost-effective alternative to noble material, Zr0.1Ce0.9O2-delta (ZDC) plays a crucial role in industrial catalysis, including applications such as automotive exhaust treatment, solid oxide fuel cells, and the catalytic combustion of hydrocarbons, due to its excellent oxygen storage capacity, high thermal stability, and resistance to carbon deposition. An important new approach for optimizing the performance of Zr0.1Ce0.9O2-delta as a catalyst is the in-situ exsolution of metal nanoparticles. Exsolution is recognized as a promising strategy for generating highly dispersed nanoparticles on the catalyst support, enhancing catalytic activity and stability. Herein, transition metal cations (Fe, Co, Ni and Cu ions) are doped into the ZDC fluorite-structured oxides (ZDCM) and exsolved on its surface under reduction conditions (ZDCM-R, M = Fe, Co, Ni and Cu). X-ray photoelectron spectroscopy and Raman spectroscopy confirm that the exsolution of Co and Cu generated an oxygen-vacancy-rich layer on the support surface, which significantly enhanced their catalytic performance. As a result, both ZDCCu-R and ZDCCo-R catalysts were able to achieve complete CO oxidation at temperatures below 200 degrees C. Moreover, ZDCCobased anodes have shown a maximum power density of 348.2 mW at 800 degrees C and demonstrated exceptional stability during direct methane utilization in solid oxide fuel cells.

Solid oxide fuel cells (SOFCs) have gained great interest due to their low pollutant emissions and superior energy conversion efficiency. The perovskite oxide La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM) is well-known for its exceptional oxygen-ion conductivity, making it an ideal electrolyte for intermediate-temperature SOFCs. However, producing LSGM pellets requires a complex, multi-step process that includes powder preparation, compaction, and high-temperature sintering, which introduce significant challenges to the manufacturing process. In this study, we utilized aqueous tape casting, an environmentally friendly, cost-effective and operationally simple technique, to fabricate uniform LSGM ceramic tapes. After sintering at 1420 °C, the LSGM electrolyte pellets produced were thin, homogeneous, and displayed a uniform elemental distribution. Furthermore, this study comprehensively analyzes the rheological properties of the casting slurry, the sintering behavior of the green tapes, and the electrochemical performance of the LSGM electrolyte. Additionally, the cell was subsequently assembled using screen printing and sintering techniques with the structure of NiO-Ce 0. 8 Gd 0. 2 O 2 (GDC) | GDC | LSGM | La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3–δ (LSCF). It demonstrated an open-circuit voltage of 1.08 V at 850 °C and achieved a maximum power density of 1.50 W/cm² under wet hydrogen conditions. Following the modification of the LSCF air electrode with Pr 6 O 11 via impregnation, the peak power density was further enhanced to 1.67 W/cm² at 850 °C. The mechanism contributing to the performance enhancement was examined by a combination of electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analysis. Keywords Aqueous tape casting, LSGM, Solid oxide fuel cells, NiO-GDC, Impregnation

Chemical compatibility in oxidizing and reducing environments between sealants and interconnects for planar solid oxide fuel cells (SOFC) are investigated. (Co,Mn)3O4, Co-Mn, and Al coatings were prepared on the FeCr-based ferritic-stainless-steel (SUS430). The (Co,Mn)3O4 coating exhibited water vapor bubble formation at the outer sealing edges when exposed to H2, indicating reactions between the coating and sealant. Co-Mn metal coating was found readily oxidized in an oxidizing environment. The glass with 5 wt% Al2O3 addition helped mitigate the Cr diffusion into sealant based on bare SUS430 substrate. Moreover, the Al metal layer effectively blocked the diffusion of Cr into the sealant at the interface and environment for 100 h, with a thickness of only 1 & mu;m. At the constant discharge current of 24 A, the voltage is stabilized at about 4.2 V for 48 h using H2 as fuel gas in 5-cell stack.

Solid oxide electrolysis cell(SOEC) could be a potential technology to afford chemical storage of renewable electricity by converting water and carbon dioxide.In this work,we present the Ni-doped layered perovskite oxides,(La 4 Sr n-4 ) 0.9 Ti 0.9n Ni 0.1n O 3n+2 with n=5,8,and 12(LSTNn) for application as catalysts of CO 2 electrolysis with the exsolution of Ni nanoparticles through a simple in-situ growth method.It is found that the density,size,and distribution of exsolved Ni nanoparticles are determined by the number of n in LSTNn due to the different stack structures of TiO 6 octahedra along the c axis.The Ni doping in LSTNn significantly improved the electrochemical activity by increasing oxygen vacancies,and the Ni metallic nanoparticles afford much more active sites.The results show that LSTNn cathodes can successfully be manipulated the activity by controlling both the n number and Ni exsolution.Among these LSTNn(n=5,8,and 12),LSTN8 renders a higher activity for electrolysis of CO 2 with a current density of 1.50A cm -2 @2.0 V at 800℃ It is clear from these results that the number of n in(La 4 Sr n-4 ) 0.9 Ti 0.9n Ni 0.1n O 3n+2 with Ni-doping is a key factor in controlling the electrochemical performance and catalytic activity in SOEC.

Titanates capable of exsolving B-site metals have shown great potential as fuel electrode in solid oxide cells (SOCs). The well-anchored nano-particles are found to exhibit superior electrocatalytic activity and resistance towards carbon deposition. Here, in order to investigate the intrinsic properties of exsolved particles under redox conditions, we selected La0.43Ca0.37Ni0.06Ti0.94O3-δ (LCNT), La0.43Ca0.37Ni0.03Fe0.03Ti0.94O3-δ (LCNFT), and La0.8Ce0.1Ni0.4Ti0.6O3 (LCeNT) as model electrode materials to exsolve Ni, Ni-Fe alloy, and Ni-CeO2, respectively. The influence of co-doping, doping level, and A-site deficiency on the exsolution process and the behavior of the exsolved particles upon oxidation were studied and characterized. The results suggest that all three materials exsolved nano-particles after reduction with different size and population, yet they tend to follow a similar trend upon oxidation.

Construction of ceria-metal/titanate heterostructure via exsolution is a promising strategy to improve the catalytic activity of titanate perovskites and broaden their applications in various energy conversion scenarios. However, the species exsolved after reduction are limited to reducible metal cations, such as Ni, Co, Fe, and precious metals. Herein, we report a modified exsolution approach for co-exsolving active oxides and metal nanoparticles from a titanate perovskite, La0.8Ce0.1Ni0.4Ti0.6O3-delta (LCeNT). We highlight strained facet-specific CeO2 cubes can be grown on the support after an air-annealing process with their morphology tunable by varying annealing temperature, whilst exsolution of Ni nanoparticles form subsequently following chemical/ electrical reduction. An electrolyte-supported SOFC utilizing CeO2-Ni@LCeNT anode achieves maximum power density of 642 mW cm-2 at 900 degrees C in H2 (-3% H2O). Exceptional robustness of the heterostructure is illustrated after running the cell in CH4 (-3% H2O) for 20 h. Overall, this work demonstrates an intriguing pathway to constructing stable and active ceria-metal/titanate heterostructure for energy applications.

alpha-PbO2-type Mn0.5Ti0.5NbO4-based oxides are studied as cathode materials in solid oxide electrolysis cell (SOEC) for the direct electrolysis of steam or CO 2 at 800 degrees C. Comparison between Mn0.5Ti0.5NbO4 and the Fe-doped ones, Fe0.3Mn0.35Ti0.35NbO4 and Fe0.6Mn0.2Ti0.2NbO4, indicates that the Fe3+ doping increases the electric conductivity in air but decreases the stability of the alpha-PbO2 structure in reducing atmosphere as in Fe0.6Mn0.2Ti0.2NbO4. The electric conductivity in reducing atmosphere is found to be ascribed to Ti4+-O-Ti3+ and Fe3+-O-Fe2+ in Mn0.5Ti0.5NbO4 and Fe doped ones, respectively. The steam or CO2 electrolsysis indicates that 30% Fe3+ substitution for Mn/Ti decreases the polarization resistance at low bias, but 60% Fe doping increases the polarization resistance dramatically than Mn0.5Ti0.5NbO4. The excessive Fe3+ doping is found to induce the phase transformation and delamination on the cathode/electrolyte interface under a cathodic current. The electrolyser with Fe0.3Mn0.35Ti0.35NbO4 cathode on zirconia-based electrolyte imparts a stable current density of 2.32 Acm(-2) at -1.6 V if Ar-88% H2O is used as feeding gas. Analysis of the gas product indicates that H-2 is produced and the Faradaic efficiency at -1.4 V and -1.6 V is found to be 100% and 93%, respectively.

In this work, we focus on investigating the titanate perovskites with exsolved Ni-Co alloy nanocatalysts as fuel electrode of solid oxide cells (SOCs), particularly on operando generating these nanomaterials via applying a potential bias in CO2 electrolysis operating conditions. Three compositions of titanate perovskite were examined, including La0.43Ca0.37Ti0.94Ni0.06O3-δ (LCT-Ni6), La0.43Ca0.37Ti0.94Ni0.03Co0.03O3-δ (LCT-Ni3Co3), and La0.43Ca0.37Ti0.90Ni0.05Co0.05O3-δ (LCT-Ni5Co5). Various techniques, including X-ray diffraction, thermogravimetric analysis, DC conductivity measurement etc., were applied to study the crystal structure, reduction behavior, conductivity property, and microstructure of these materials. SOCs with these titanate fuel electrodes were fabricated and evaluated, with emphasis placed on operando generation of active nanomaterials through electrochemical switching in pure CO2 atmosphere, and on understanding the materials properties linking to their microstructure and performance towards CO2 electrolysis and H2 fuel cell.

Employment of identical oxides for the cathode and anode in a symmetrical solid oxide fuel cell (SSOFC) is beneficial for decreasing the fabrication costs of a robust cell. Ce doping on the A site of SrFeO3 increased the structural stability in a reducing atmosphere, but ceria was found to exsolve from the perovskite during the cooling process in the air if the doping level reached 20 atom %. The additional doping of 5 atom % Ru in Sr0.8Ce0.2FeO3 on the Fe site could prevent the ceria segregation in air and induce the surface decomposition under fuel conditions for the formation of nanoscale SrO, CeO2, and Ru-0. The SSOFC with Ce/Ru codoped SrFeO3 on a Sr- and Mg-doped LaGaO3 electrolyte showed a small R-p value (0.12 Omega cm(2)) when H-2 and ambient air were used as fuel and oxidant, respectively. The peak power densities of 846 and 310 mW cm(-2) were achieved at 800 degrees C using H-2 and C3H8 as fuel, respectively. The excellent coke resistance of the anode could be related to the simultaneous in situ exsolution of CeO2, SrO, and Ru-0 nanoparticles.

Growth of finely dispersed nanocatalysts by exsolution of metal nanoparticles from perovskite oxides under reducing conditions at elevated temperature is a promising approach of producing highly active catalytic materials. An alternative method of exsolution using an applied potential has been recently shown to potentially accelerate the exsolution process of nanoparticles that can be achieved in minutes rather than the hours required in chemical reduction. In the present study, we investigate exsolution of nanoparticles from perovskite oxides of La0.43Ca0.37Ni0.06Ti0.94O3-gamma (LCTNi) and La0.43Ca0.37Ni0.03Fe0.03Ti0.94O3-gamma (LCTNi-Fe) under applied potentials in carbon dioxide atmosphere. The impedance spectra of single cells measured before and after electrochemical poling at varying voltages showed that the onset of exsolution process occurred at 2 V of potential reduction. An average particle size of the exsolved nanoparticles observed after testing using a scanning electron microscopy was about 30-100 nm. The cells with the reduced electrodes exhibited desirable electrochemical performances not only in pure carbon dioxide (current density of 0.37 A cm(-2) for LCTNi and 0.48 A cm(-2) for LCTNi-Fe at 1.5 V) but also in dry hydrogen (0.36 W cm(-2) for LCTNi and 0.43 W cm(-2) for LCTNi-Fe). (c) 2019 Elsevier Ltd. All rights reserved.

Due to the large amount of carbon dioxide in biogas reducing its flame velocity, flammability range, heating value as well as power output, the biogas must be upgraded to a higher value product. In this paper, direct feeding of simulated biogas to SOECs has been investigated; in particular, two different fuel electrode materials which are nickel with 8% yttrium-stabilized zirconia (Ni-YSZ) and La0.43Ca0.37Ni0.05Ti0.95O3- (LCNT) incorporated with 8 mol% yttrium-stabilized zirconia (8YSZ) electrolyte and La1− xSrxMnO3 perovskite (LSM)–yttria-stabilized zirconia (YSZ) composite air electrode have been tested. Both cells demonstrate feasible way for biogas electrolysis.

The key technical challenges that fuel cell developers need to address are performance, durability, and cost. All three need to be achieved in parallel; however, there are often competitive tensions, e.g., performance is achieved at the expense of durability. Stability and resistance to degradation under prolonged operation are key parameters. There is considerable interest in developing new cathodes that are better able to function at lower temperature to facilitate low cost manufacture. For anodes, the ability of the solid oxide fuel cell (SOFC) to better utilize commonly available fuels at high efficiency, avoid coking and sulfur poisoning or resistance to oxidation at high utilization are all key. Optimizing a new electrode material requires considerable process development. The use of solution techniques to impregnate an already optimized electrode skeleton, offers a fast and efficient way to evaluate new electrode materials. It can also offer low cost routes to manufacture novel structures and to fine tune already known structures. Here impregnation methodologies are discussed, spectral and surface characterization are considered, and the recent efforts to optimize both cathode and anode functionalities are reviewed. Finally recent exemplifications are reviewed and future challenges and opportunities for the impregnation approach in SOFCs are explored.

The electrochemical performance of LiCoPO4 (LCP) as a high-voltage positive electrode for lithium-ion batteries is significantly improved by using the aqueous binder sodium carboxymethyl cellulose (CMC). The CMC not only provides a uniform electrode surface as shown by scanning electron microscopy and elemental mapping, but also suppresses the degradation of LiCoPO4 by scavenging HF in the electrolyte solution as demonstrated by FT-IR. In comparison with other water-soluble binders such as sodium alginate (ALG) and polyacrylic acid sodium salt (PAA), the homogeneous distribution of CMC within the electrodes accompanied by high accessibility of carboxylate groups in CMC are shown to be crucial factors to achieve enhanced performance with an excellent capacity retention of 94% after 20 cycles at a rate of C/10.

In recent years infiltration of materials into porous ceramic scaffolds has been shown to be an effective way of creating catalytically active components for solid oxide fuel cells (SOFCs). However, the redox properties of these novel structures are not well understood. Here, we use X-ray photoelectron spectroscopy (XPS) and in-situ Raman spectroscopy to investigate the oxidation properties of yttria-stabilised zirconia (YSZ) scaffolds infiltrated with ceria (CeO2), gadolinium-doped ceria (GDC) and zirconia-doped ceria (ZDC), with and without Ni. XPS shows that doping ceria with zirconia increases the ratio of Ce3+ to Ce4+, while gadolinium doping results in a decrease of Ce3+. The presence of Ni increases the Ce3+/Ce4+ ratio for CeO2 and GDC, but had little effect on ZDC. We used the shift of the F-2g Raman peak to monitor in-situ, the oxidation state of ceria. In the as-made compounds, we show that while the gadolinium and zirconium dopants significantly change the oxidation characteristics of ceria, the resulting materials are only significantly reduced above 500 degrees C when co-infiltrated with Ni. In-situ Raman monitoring during reduction as a function of temperature showed that while ZDC reduces much more readily than undoped ceria or GDC, the presence of Ni dominated the reduction dynamics.

Enhancing the stability of introduced metal catalysts on oxide surfaces is a major issue for infiltrated anodes in Solid Oxide Cells (SOC) and other related catalysis field. Stoichiometric SrTiO3 (STO) and A-site cation deficient LaxSr1−3x/2TiO3 (LST) were compared to investigate the influence of stoichiometry upon the contact between metal and oxide, in order to improve the bonding of catalyst and substrate. Optimization of oxidizing and reducing temperatures for Ni infiltration processes was performed to get good nanoparticles distribution on the perovskite surface. Thermogravimetry (TG) and X-ray diffraction (XRD) analysis showed the formation of NiO, Ni after oxidation and reduction, respectively. Energy Dispersive Spectroscopy (EDS) on a Transmission Electron Microscopy (TEM) was employed to characterize the nickel nanoparticles on the LST surface. No obvious elemental transfer happened between Ni and LST. The TEM images showed Ni nanoparticles bonded well to the A-site deficient perovskite with large contact area. TG analysis in reducing atmosphere indicates interactions between metal-oxide interactions in deficient samples. This may improve the Ni distribution on perovskite surface and further control the growth of Ni particles when heated at extreme temperature.

Nickel-yttria stabilized zirconia ( Ni-YSZ) cermet anodes for solid oxide fuel cells ( SOFC) possesses excellent catalytic properties and stability for H-2 oxidation but not for hydrocarbons as it results in fast carbon deposition in absence of excess steam. In the present work, A-site deficient porous LSCTA- (La0.2Sr0.25Ca0.45TiO3) anode has been fabricated using the environment friendly, aqueous tape casting method followed by the same procedure for the dense YSZ electrolyte and YSZ porous scaffold as cathode matrix. The anode, electrolyte, and porous cathode matrix have been laminated together and sintered up to 1350 degrees C. After sintering, nitrate precursors of La, Sr, Co and Fe are infiltrated inside the porous YSZ cathode matrix to form the perovskite phases of La0.8Sr0.2CoO3 ( LSC) and La0.8Sr0.2FeO3 (LSF). The as fabricated electrolyte supported SOFCs have been tested in H-2 and CH4 fuel at 800 degrees C. The electrolyte supported cell 15% LSF-5% LSC-YSZ/YSZ/4% Ni-6%CeO2-LSCTA-gives maximum power density of 328 mW cm(-2) for 3 h in H-2, but inCH(4) the performance decreased to 165mWcm(-2) even though a sustained open circuit voltage of similar to 1 V obtained during H-2 and CH4 operation. The morphology of the anode before and after cell testing has been analyzed using scanning electron microscope followed by X-ray diffraction studies to understand phase changes during fabrication and testing. (C) 2017 The Electrochemical Society. All rights reserved.

Extensive efforts have been made to find new fuel electrode materials for solid oxide cells with high activity and durability to provide more robust materials than state-of-the-art materials, Ni-cermets.