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Modification is one of the most important and effective methods to improve the photoelectrocatalytic (PEC) performance of ZnO. In this paper, the RuxZn1−xO/Ti electrodes were prepared by thermal decomposition method and the effect of Ru content on those electrodes’ electronic structure was analyzed through the first-principles calculation. Various tests were also performed to observe the microstructures and PEC performance. The results showed that as the Ru4+ transferred into ZnO lattice and replaced a number of Zn2+, the conduction band of ZnO moved downward and the valence band went upward. The number of photogenerated electron-hole pairs increased as the impurity levels appeared in the band gap. In addition, ZnO nanorods exhibited a smaller grain size and a rougher surface under the effect of Ru. Meanwhile, the RuO2 nanoparticles on the surface of ZnO nanorods acted as the electron-transfer channel, helping electrons transfer to the counter electrode and delaying the recombination of the electron-hole pairs. Specifically, the RuxZn1−xO/Ti electrodes with 9.375 mol% Ru exhibited the best PEC performance with a rhodamine B (RhB) removal rate of 97%, much higher than the combination of electrocatalysis (EC, 12%) and photocatalysis (PC, 50%), confirming the synergy of photoelectrocatalysis.

The adsorption and separation of gases are important for mitigating the greenhouse effect, popularizing clean energy and treating volatile organic compounds (VOCs). Metal organic frameworks (MOFs) have been attracted broad attention due to their high specific surface area, adjustable pore structure and surface functionality. MOFs have been widely applied in gas adsorption and separation. The drawbacks of some MOFs are the high humidity sensitivity and poor thermal stability that hinder their industrial applications. Porous carbon materials possess high specific surface area, exceptional chemical and thermal stabilities. Porous carbon materials derived from MOFs as precursors not only overcome the shortcomings of some MOFs with poor water and thermal stabilities, but also retain the advantages of MOFs materials effectively. MOFs-derived porous carbon materials have good application prospects in gas adsorption and separation. This paper introduces the research status of MOFs-derived porous carbon materials, and focuses on their applications in the field of gas adsorption and separation. Synthesis methods for MOFs-derived porous carbon materials mainly include direct carbonization, carbonization with additional precursor and chemical activation. Specific surface area, pore size and surface functional groups of MOFs-derived porous carbon materials have great impact on their adsorption and separation performances for gases (carbon dioxide, hydrogen and volatile organic compounds). In general, MOFs-derived porous carbon materials with high surface area could exhibit excellent adsorption performance for CO2. And the pore size characteristics of MOFs-derived porous carbon materials play important roles in the adsorption capacity and diffusion rate of CO2. Nitrogen doping can improve CO2 adsorption capacities owing to Lewis acid-base interaction, electrostatic interaction and hydrogen bonding between the surface functional groups of MOFs-derived porous carbon materials and CO2. Furthermore, H2 storage is primarily determined by the narrow micropore, and chemical doping can effectively promote H2 storage of MOFs-derived porous carbon materials. In addition, VOCs adsorption is associated with the physiochemical characters of adsorbents (e.g., specific surface area, pore size, pore volume, surface chemical functional groups), properties of adsorbates (e.g., molecular weight, molecular structure, polarity, and boiling point) as well as the adsorption conditions (e.g., temperature and humidity). However, the researches on MOFs-derived porous carbon materials in gas adsorption and separation still face many challenges. (1) The pore structure, morphology and surface chemical properties of MOFs-derived porous carbon materials are directly affected by various factors, such as types of MOFs, types and amounts of additional carbon sources or additional nitrogen sources, carbonization temperature, time and atmosphere, types and ratios of activators, activation temperature and time, chemical doping and so on. (2) There are rare studies on the adsorption mechanism of MOF-derived porous carbon materials for various gases, the multi-component competitive adsorption mechanism, and the influence of environmental factors (such as environmental temperature and humidity) on the adsorption performance. (3) Environmental pollution will be caused during the chemical activation process of MOFs-derived porous carbon materials. At present, there are few reports on the recovery of pyrolysis gases and dispose of the generated waste during the activation process. (4) There is an urgent need to develop new synthetic methods for MOFs-derived porous carbon materials to achieve large-scale production. In a word, the related researches of MOFs-derived porous carbon materials can not only expand the application range of MOFs materials, but also promote the development of gas adsorption and separation. We believe that the application of MOFs-derived porous carbon materials in the field of gas adsorption and separation will make great breakthrough in the future.

Electrode/electrolyte interface plays a critical role in the performance and stability of solid oxide fuel cells (SOFCs). In the case of La0·6Sr0·4Co0·2Fe0·8O3-δ (LSCF) cathode, it is well known that cathodic polarization promotes the Sr segregation and diffusion towards the LSCF electrode and Y2O3–ZrO2 (YSZ) electrolyte interface, leading to the formation of SrZrO3 secondary phase and the disintegration of LSCF structure at the interface. On the other hand, LSCF is chemically stable with doped ceria electrolytes such as Gd-doped CeO2 (GDC). However, there appears no comparative studies on the intrinsic relationship between the surface segregation, interface reaction and stability of LSCF in YSZ and GDC electrolytes. Here, a comparative study has been carried out on the segregation and interface formation of LSCF on GDC and YSZ electrolyte under identical cathodic polarization conditions at 750 °C and 1000 mAcm−2 using focused ion beam and scanning transmission electron microscopy (FIB-STEM) techniques. Segregation of Sr occurs in the LSCF-GDC system, however, the inertness of GDC electrolyte suppresses the segregation process of Sr species. Instead, surface segregation of B-site Co cation becomes dominant under the cathodic polarization, forming isolated CoOx particles. The results indicate that the existence of chemical catchers such as Zr in the case of YSZ electrolyte for the segregated Sr species is kinetically the driving force for the Sr segregation and stability of LSCF electrodes under SOFC operation conditions.

Solid oxide cells (SOCs) are highly efficient and environmentally benign devices that can be used to store renewable electrical energy in the form of fuels such as hydrogen in the solid oxide electrolysis cell mode and regenerate electrical power using stored fuels in the solid oxide fuel cell mode. Despite this, insufficient long-term durability over 5–10 years in terms of lifespan remains a critical issue in the development of reliable SOC technologies in which the surface segregation of cations, particularly strontium (Sr) on oxygen electrodes, plays a critical role in the surface chemistry of oxygen electrodes and is integral to the overall performance and durability of SOCs. Due to this, this review will provide a critical overview of the surface segregation phenomenon, including influential factors, driving forces, reactivity with volatile impurities such as chromium, boron, sulphur and carbon dioxide, interactions at electrode/electrolyte interfaces and influences on the electrochemical performance and stability of SOCs with an emphasis on Sr segregation in widely investigated (La,Sr)MnO3and (La,Sr)(Co,Fe)O3−δ. In addition, this review will present strategies for the mitigation of Sr surface segregation.Graphic Abstract

Glass and glass-ceramic are one of the key sealing materials for solid oxide fuel cells (SOFCs) and they need to meet stringent requirements for long-term operation at high temperatures. Here, we report for the first time the incorporation of aluminum nitride (AlN) dopant into borosilicate glasses and glass-ceramics so as to tailor their basic properties and sealing performance. The results show the AlN-doped glass-ceramics exhibit remarkably enhanced thermal stability and chemical compatibility when adhering to Y2O3-ZrO2 electrolyte. The electrical conductivity is also significantly reduced by the AlN doping, and the conductivity of 15 wt.% AlN-doped glass-ceramic is nearly two orders of magnitude lower than that of the undoped glass-ceramic. This work indicates that AlN doping is an effective strategy to obtain a reliable borosilicate glass-ceramics for SOFCs.

Combined chromium and sulfur poisoning for La0.8Sr0.2MnO3-δ (LSM) cathodes of solid oxide fuel cells (SOFCs) were investigated with cathodic current of 200 mA cm−2 under 800 °C for 22 h. After polarization in chromium and sulfur at 800 °C for 22 h, polarization and ohmic resistance for LSM electrodes were 5.1 Ω cm2 and 7.62 Ω cm2, which were larger than values of LSM electrodes after chromium deposition only and sulfur deposition only. EDS, XPS and XRD results showed chromium and sulfur deposition occurred especially in bulk of the electrode, forming SrCrO4 and SrSO4. Compared with chromium deposition only, sulfur deposition only, combined chromium and sulfur deposition was not random and the degradation phenomenon of chromium and sulfur poisoning was much more severe. The combined chromium and sulfur deposition of LSM electrodes was induced by interaction among CrO, SO2 and segregated SrO from LSM electrode. Thermodynamic predictions have been carried out utilizing CALPHAD approach, which were found in agreement with observed experimental results.

A novel molten salt method was employed to synthesize 10% Nb doped La0.6Sr0.4FeO3−δ (LSFN). The as-synthesized powders were pure and adopted a porous structure. Using LSFN as the oxygen electrode for a reversible solid oxide cell, the button cell exhibited a peak power density of 0.79 W cm−2 in H2 and an electrolysis current density of 0.89 A cm−2 at 1.3 V in 50% CO2/50% H2 at 800 °C. A large fraction of Fe2+ was found in LSFN, resulting in the improved performance. Our results indicate that the molten salt method is a promising approach for the synthesis of highly active perovskite electrode with a dopant of Nb.

A novel high-performance epoxy resin diphenyldi (9,9-Di-(4-(2,3-epoxypropoxy) phenyl)-4,5-diazafluorenoxysilane) (DEPFS) containing the diazafluorene and silicon group was synthesized by the nucleophilic substitution for the first time and added to bisphenol A epoxy resin (E-51) to form a thermoset blend. We observed that the incorporation of DEPFS remarkably enhanced the flame retardancy and thermal properties of E-51. The cured E-51-30% DEPFS thermoset exhibited a glass transition temperature of 187 °C and a limiting oxygen index of 30.1%, much higher than 153 °C and 22.6% for those of pristine E-51 thermoset, respectively. In addition, the incorporation of DEPFS has dual enhancement effects on the toughness and tensile strength of E-51. This study provides an effective means to prepare a high-performance epoxy resins and proposes flame retardancy and simultaneous reinforcing and toughening mechanism. It was found that the DEPFS with diverse performance has allowed an increasing number of versatile industrial application such as microelectronics, electronics, aerospace and so on.

The high volatility of boron from borosilicate glass sealants often leads to boron deposition and poisoning of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode, presenting a challenge for the development of reliable solid oxide fuel cells (SOFCs). In this paper, we report that boron volatilization from borosilicate glass at 700 °C can be significantly suppressed by appropriate NiO dopant, mainly due to the increase of Si-O-B linkages in the combining B-O− and Si-O− network. Also, the formation of boron-containing phase in NiO-doping glass-ceramics has been studied, which suppresses the reaction between glass and LSCF cathode after heat treatment at 700 °C for 1000 h. Moreover, the change of crystalline phases leads to an improvement in thermal and electrical properties. We believe that our findings will open a new way for the design and development of the reliable sealing glass for SOFCs applications.

Crack formation at the interface between sealing glass and other cell components is one of the key issues in constraining the development of solid oxide fuel cells (SOFCs). Herein, we report our finding on tuning the mechanical and thermal properties of borosilicate glass by doping Nb2O5. We observe the formation of Ba3Nb10O28 crystalline phase in the Nb2O5-doped glass, leading to significantly enhanced crack-resistant and self-healing abilities of the glass. In addition, we demonstrate long-term thermal and chemical stability at the sealing interface between the Nb2O5-doped glass-ceramics and Y2O3-ZrO2 electrolyte after heat-treatment at 700 °C for 1000 h. The possible mechanism for the improved crack-resistant and self-healing properties is discussed.

In this study, pyrochlore Pr2B2O7 oxides (B Zr, ZrSn, Sn, PZO/PZSO/PSO) and perovskite (B Ti, PTO) were prepared as direct ammonia solid oxide fuel cell (DA-SOFC) cathode with oxygen reduction reaction activity induced by B-site cationic defects. Compared with PTO, the pyrochlore PBO with unoccupied 8a-oxygen sites are high in inherent oxygen vacancies (ca. 12.5%), leading to enhanced migration of lattice oxygen. Among the n-type semiconductors, PZO is with a more negative flat-band potential and is more effective in terms of overcoming energy barriers. As a result, the conductivity of PZO is two orders of magnitude higher than that of PTO at 800 °C. The oxygen transport performance reveals that the surface exchange coefficient of PZO is about one order of magnitude higher than that of La0.7Sr0.3MnO3-δ at 900 °C. Owing to high conductivity, fast oxygen transport, and matched thermal expansion coefficient, an anode-supported DA-SOFC using the PZO-based cathode can offer a maximum power density of 0.25 W cm−2 at 600 °C and 1.22 W cm−2 at 800 °C, operating continuously over 100 h without obvious degradation. The electrochemical performance is 2.3 folds higher than those of SOFCs using other PBO-based cathode, and higher than most reported SOFCs with the cathodes using A-site Pr.

Bismuth-based oxides exhibit outstanding oxygen ionic conductivity and fast oxygen surface kinetics and have shown great potential as a highly active component for electrode materials in solid oxide fuel cells (SOFCs). Herein, a Nb-doped La0.6Sr0.4Co0.2Fe0.7Nb0.1O3-δ (LSCFNb) electrode with 40% Er0.4Bi1.6O3 (ESB) composite electrode was successfully fabricated by decoration method and directly assembled on barrier-layer-free yttrium-stabilized zirconia (YSZ) electrolyte cells, achieving a peak power density of 1.32 W cm-2 and excellent stability at 750 °C and 250 mA cm-2 for 100 h. ESB decoration also significantly reduces the activation energy from 214 kJ mol-1 for the O2 reduction on pristine LSCFNb electrode to 98 kJ mol-1. Further microstructural analysis reveals that there is a redistribution and migration of the ESB phase in the ESB-LSCFNb composite toward the YSZ electrolyte under the influence of cathodic polarization, forming a thin ESB layer at the cathode/YSZ electrolyte interface. The in situ formed ESB layer not only prevents the direct contact and subsequent reaction between segregated SrO and YSZ electrolytes, but also remarkably promotes the oxygen migration/diffusion at the interface for O2 reduction reaction, resulting in a remarkable increase in power output and a decrease in activation energy. The present study clearly demonstrated the in situ formation of a highly functional and active ESB protective layer at LSCFNb cobaltite cathode and YSZ electrolyte interface via ESB-decorated LSCFNb composite cathode under SOFC operation conditions.

Phosphate glass is advantageous as a low temperature sealing material, especially in solar cells, micro-motor systems, vacuum engineering and the like, but the poor chemical stability restricts its wide application, especially in humid environments. To overcome this shortcoming, a certain proportion of silicon nitride is added to tailor the structural, chemical and thermal properties of phosphate glass. The results show that the addition of silicon nitride improves the water resistance and remarkably reduces the mass loss in humid environments from 60 to 3 wt% after 120 h. With the addition of silicon nitride, the softening temperature of glass is in the range of 330–372 °C. In particular, the coefficient of thermal expansion of phosphate glass can be tailored ranging from 14.9 × 10−6 K−1 to 17.4 × 10−6 K−1 by adjusting the content of silicon nitride, making it thermally compatible with various substrates. These findings provide useful information on the development of reliable low-temperature sealing glass.

This work was financially supported by the Australian Research Council under the Discovery Project Scheme (project numbers: DP180100731 and DP180100568), and by the Guangdong Provincial Department of Science and Technology Agency (GDST) under the GDST-NOW Science-Industry Cooperation Program (No. 2017A050501053). The establishment of intimate electrode/electrolyte interface is very important in solid oxide fuel cells (SOFCs), because it plays a critical role in the overall cell performance and durability. In this study, Mn segregation and interface formation between directly assembled La0.8Sr0.2MnO3 (LSM) electrode and yttrium-stabilized zirconia (YSZ) or gadolinium-doped ceria (GDC) electrolytes are studied using combined focused ion beam and scanning transmission electron microscopy (FIB-STEM). In the case of LSM/YSZ and LSM/GDC electrodes, a significant reduction in the electrode ohmic resistance is observed after cathodic polarization at 900 °C and 500 mA cm−2, indicating the formation of an intimate interface. However, LSM particles start to disintegrate at the electrode/electrolyte interface with the increase of polarization time in the case of LSM/YSZ electrode. On the other hand, the LSM/GDC interface is very stable with negligible microstructure change at the interface. Mn segregation from the LSM perovskite structure is identified under the influence of polarization in both LSM/YSZ and LSM/GDC electrodes. The results demonstrate that nature of the electrolyte plays a critical role in the electrochemical activity, microstructure, morphology and stability of LSM/electrolyte interface under SOFC operation conditions. Postprint

The rigid nature of sealing glass-ceramics restricts the thermal cycling stability of Solid Oxide Fuel Cells (SOFCs), which thus evokes an interest in designing a sealing glass without crystallization under the operational condition of SOFCs. In this paper, we report that the sealing performance of 30Na2O-70SiO2 (in mole%) glass-ceramic can be significantly improved by Fe2O3 dopant through a composite approach. In particular, the crystallization in glass can be suppressed by appropriate Fe2O3 dopant amount (8 mol%), which results in the improved sealing property of glass. In addition, the glass modified with Fe2O3 shows good chemical compatibility with 8 mol% yttria-stabilized zirconia (8YSZ) electrolyte and metallic interconnect (430 stainless steel) in dual atmospheres. The possible mechanism for the improved sealing performance of 30Na2O-70SiO2 glass-ceramic by this unique composite approach is also discussed.

Bismuth oxide is as an active promoter in enhancing the ionic conductivity and electrocatalytic activity of manganite oxygen electrodes of solid oxide cells, but there are very limited reports on the formation and evolution of electrode/electrolyte interface of bismuth oxide-manganite composite electrode under the influence of electrochemical polarization. Herein, we report the effect of electrochemical polarization and direction of polarization current on the electrocatalytic performance and electrode/electrolyte interface of a (La0·8Sr0.2)0.95Mn0·95Pt0·05O3+δ-Er0.4Bi1·6O3 (LSMPt-ESB) composite oxygen electrode assembled on zirconia electrolyte. The cell with the LSMPt-ESB electrode produces outstanding performance for power generation and steam splitting, and it is stable without noticeable degradation during operation at 600 °C for 350 h in the fuel cell mode. The cathodic polarization induces in operando formation of electrode/electrolyte interface with observation of an Er-deficient LSMPt-ESB dense layer and Er-rich (Er,Bi,Mn)Ox particles on the zirconia electrolyte surface. This is different to the case of dwell under open circuit and in particular under anodic polarization conditions. The present study gains insights into the development of high performance, reliable bismuth oxide-manganite composite oxygen electrode for reduced temperature solid oxide cells.

Cellular metals with a large surface-to-volume ratio and excellent electrical conductivity have attracted great attention due to their wide application. However, the existing processes for fabrication of cellular metallic structures are generally complex and dependent on the sacrificial materials or templates, and therefore, it is highly desirable to develop a facile process. Herein, we propose a novel gas-assisted reconstruction strategy for in situ fabrication of micron-porous architectures on Ag precursor metal using a CH4/O2 gas mixture at 750 °C. The obtained results indicate that large-area and clean, porous Ag architectures are successfully created through the treatment in CH4/O2 gas. The formation of cellular structure is mainly due to the simultaneous diffusion of H2, CO and O2 into Ag bulk and fast reaction at elevated temperatures. The process is clean and applicable to creation of porous architectures (from surface texturing to 3-D cellular structure) on Ag metal, avoiding the use of sacrificial materials or templates. Furthermore, we have demonstrated that the formed micron-porous Ag sheet with large effective area, high electrical conductivity can be directly used as a free-standing electrode for electrochemical supercapacitors with a high capacitance.

At present, the insufficient thermo-mechanical stability of sealing glass presents a challenge for solid oxide fuel cells (SOFCs). In this work, we report for the first time that a rigid-resilient transition occurs in a calcium borosilicate sealing glass upon heating at 700 °C for different durations. The elastic modulus increases from 28.1–40.0 GPa for 24 h to 92.3–105.1 GPa for 100 h, while the corresponding hardness increases from 2.5–3.1 GPa to 8.1–9.2 GPa. In addition, a possible mechanism for the rigid-resilient transition has been proposed. The reported results provide a new approach to solve the sealing problem of SOFCs.

In this work, a phosphor for white light-emitting diode (LED) application, Ce3+-doped yttrium aluminum garnet (YAG:Ce3+), was successfully packaged using a P2O5-ZnO-Na2O-Al2O3 glass-ceramic system, through a vertical deposition method. Here, we found that white light can be achieved by combining the packaged phosphor with a blue chip (e.g. InGaN). The specimen doped with 4 mol% Al2O3 showed a luminous efficacy (LE) of 125.8 lm W−1, at a correlated color temperature (CCT) of 5769 K, with a color rendering index (CRI) of 68. In addition, the LE loss of the specimen doped with 4 mol% Al2O3 was only 3.6% after heat treatment at 150 °C for 1200 h, which is significantly lower than that of traditional resin (19.3%). Moreover, a possible mechanism for reducing the LE loss using glass-ceramics was proposed.

Boron volatility is one of the most important properties of borosilicate-based glass sealants in solid oxide fuel cells (SOFCs), as boron contaminants react with lanthanum-containing cathodes, forming LaBO3 and degrading the activity of SOFCs. Here, we report that the reaction between the volatile boron and a La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode during polarization can be significantly reduced by doping aluminoborosilicate glass with Gd2O3. Specifically, the Gd cations in glass with 2 mol.% Gd2O3 dissolve preferentially in the borate-rich environment to form more Gd-metaborate structures and promote the formation of calcium metaborate (CaB2O4); they also condense the B–O network after heat treatment, which suppresses poisoning by boron contaminants on the LSCF cathode. The results provide insights into design and development of a reliable sealing glass for SOFC applications.

Active and stable oxygen electrode is probably the most important in the development of solid oxide electrolysis cells (SOECs) technologies. Herein, we report the successful development of mixed ionic and electronic conducting (MIEC) La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) perovskite oxides directly assembled on barrier-layer-free yttria-stabilized zirconia (YSZ) electrolyte as highly active and stable oxygen electrodes of SOECs. Electrolysis polarization effectively induces the formation of electrode/electrolyte interface, similar to that observed under solid oxide fuel cell (SOFC) operation conditions. However, in contrast to the significant performance decay under SOFC operation conditions, the cell with directly assembled LSCF oxygen electrodes shows excellent stability, tested for 300 h at 0.5 A cm−2 and 750 °C under SOEC operation conditions. Detailed microstructure and phase analysis reveal that Sr segregation is inevitable for LSCF electrode, but anodic polarization substantially suppresses Sr segregation and migration to the electrode/electrolyte interface, leading to the formation of stable and efficient electrode/electrolyte interface for water and CO2 electrolysis under SOECs operation conditions. The present study demonstrates the feasibility of using directly assembled MIEC cobaltite based oxygen electrodes on barrier-layer-free YSZ electrolyte of SOECs.

Sulphur poisoning for state-of-the-art La0.8Sr0.2MnO3-δ (LSM) anodes of solid oxide electrolysis cell (SOEC) was studied under anodic current of 200 mA/cm2 in 1 ppm SO2 air. After polarization in 1 ppm SO2-containing air at 800 °C for 40 h, electrode polarization resistance as well as ohmic resistance of LSM electrodes were measured 24.83 Ω cm2 and 6.09 Ω cm2, which were around 4 as well as 3 times than initial values of LSM electrodes. Sulphur deposition prefers to take place at the LSM/YSZ interface and inner layer for LSM electrodes, leading to the formation of SrSO4 compounds, which is confirmed by XRD and then leads to the microstructural change of the LSM electrodes. The anodic polarization promotes the SrO segregation, which is supported by the observation of the deposition of SrSO4 compounds, accelerating LSM electrodes delamination. The results indicate the obvious poisoning effect for sulphur species of electrochemical activity as well as stability of SOEC electrodes.

Sr doping is a common strategy to enhance the electrocatalytic activity of perovskite cathode materials of solid oxide fuel cells (SOFCs), but the tendency of Sr surface segregation, chemical incompatibility with yttria-stabilized zirconia (YSZ) and interaction with volatile contaminants such as chromium in SOFC stacks lead to a loss of long-term cell performance. Herein, a Sr-free and Pd-doped La0.95Co0.19Fe0.76Pd0.05O3-δ (LCFPd) cathode is directly assembled on a barrier-layer-free YSZ electrolyte cell without conventional high temperature pre-sintering. The cell with the directly assembled LCFPd-GDC (gadolinium-doped ceria) composite cathode exhibits a peak power density of 1035 mW cm− 2 and excellent operation stability at 750 °C for 200 h. Cathodic polarization significantly enhances the electrode/electrolyte interface contact, indicated by the substantial decrease of cell ohmic resistance from 0.28 Ω cm2 to 0.14 Ω cm2 after polarization at 500 mA cm− 2 and 750 °C for 120 h. Detailed elemental analysis indicates that doped Pd could be segregated on the electrode surface under fuel cell operation conditions, which significantly enhances the electrocatalytic activity for the O2 reduction reaction. This study provides new strategy to develop cobaltite based perovskite materials directly on YSZ electrolyte.

La0.6Sr0.2Co0.2Fe0.8O3-δ (LSCF) is the most intensively investigated high performance cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs), but strontium segregation and migration at the electrode/electrolyte interface is a critical issue limiting the electrocatalytic activity and stability of LSCF based cathodes. Herein, we report a Nb and Pd co-doped LSCF (La0.57Sr0.38Co0.19Fe0.665Nb0.095Pd0.05O3-δ, LSCFNPd) perovskite as stable and active cathode on a barrier-layer-free anode-supported yttria-stabilized zirconia (YSZ) electrolyte cell using direct assembly method without pre-sintering at high temperatures. The cell exhibits a peak power density of 1.3 W cm−2 at 750 °C and excellent stability with no degradation during polarization at 500 mA cm−2 and 750 °C for 175 h. Microscopic and spectroscopic analysis show that the electrochemical polarization promotes the formation of electrode/electrolyte interface in operando and exsolution of Pd/PdO nanoparticles. The Nb doping in the B-site of LSCF significantly reduces the Sr surface segregation, enhancing the stability of the cathode, while the exsoluted Pd/PdO nanoparticles increases the electrocatalytic activity for the oxygen reduction reaction. The present study opens up a new route for the development of cobaltite-based perovskite cathodes with high activity and stability for barrier-layer-free YSZ electrolyte based IT-SOFCs.

The high reactivity between bismuth oxide and cobaltite oxygen electrodes is a bottleneck in developing active and reliable bismuth oxide–cobaltite composite oxygen electrodes for solid oxide cells (SOCs). Herein, a Sr-free Sm0.95Co0.95Pd0.05O3−δ (SmCPd) oxygen electrode decorated with nanoscale Er0.4Bi1.6O3 (ESB) is synthesized and assembled on a barrier-layer-free Y2O3–ZrO2 (YSZ) electrolyte film. The cell with the ESB decorated SmCPd composite oxygen electrode exhibits a peak power density of 1.81 W cm−2 at 750 °C and 0.58 W cm−2 at 650 °C. More importantly, excellent operating stability is achieved in the fuel cell mode at 600 °C for 500 h, and in electrolysis and reversible modes at 750 °C for over 200 h. The results demonstrate the feasibility of applying bismuth oxide–cobaltite composite oxygen electrodes in developing high-performance and durable SOCs.

In this paper, critical role of infiltrated nanoparticles (NPs) on the electrocatalytic activity of cathodes of solid oxide fuel cells (SOFCs) for O2 reduction reaction is studied on well-defined and microstructurally clean Pt electrodes using infiltrated La0.8Sr0.2CoO3 (LSC), La0.8Sr0.2Co0.5Mn0.5O3 (LSCM), and La0.8Sr0.2MnO3 (LSM) NPs. The promotion factor, fp, as defined as the ratio of electrode polarization resistance, RE of the electrode prepared by the conventional method to that of the infiltrated electrode measured under identical conditions, is close to unit for the 0.2 mg cm−2 NPs infiltrated Pt electrodes, indicating that the promotion effect of infiltrated perovskite NPs on the electrocatalytic activity of Pt electrodes is very small or negligible under open circuit conditions. However, under dc bias of 100 mV, fp is 35, 18 and 7 for the infiltrated LSC-Pt, LSCM-Pt and LSM-Pt electrodes, respectively. The electrode activity is significantly promoted by the presence of the NPs under cathodic polarization conditions. The electrochemical activity of Pt electrodes with infiltrated NPs depends strongly on the nature of the infiltrated materials with the order of LSC > LSCM > LSM. The higher oxygen surface exchange rate as well as faster oxygen transportation kinetics of the B-site Co-rich perovskite oxides is responsible to the better catalytic activity of the infiltrated Pt cathodes.

The crystal structure and thermal expansion of the perovskite samarium cobalt oxide (SmCoO3) have been determined over the temperature range 295–1245 K by Rietveld analysis of X-ray powder diffraction data. Polycrystalline samples were prepared by a sol–gel synthesis route followed by high-temperature calcination in air. SmCoO3 is orthorhombic (Pnma) at all temperatures and is isostructural with GdFeO3. The structure was refined as a distortion mode of a parent $ Pm{\bar 3}m $ structure. The thermal expansion was found to be non-linear and anisotropic, with maximum average linear thermal expansion coefficients of 34.0(3) × 10−6, 24.05(17) × 10−6, and 24.10(18) × 10−6 K−1 along the a-, b-, and c-axes, respectively, between 814 and 875 K.

Nb2O5 is added to a borosilicate sealing system to improve the thermo-mechanical stability of the sealing interface between the glass and Fe-Cr metallic interconnect (Crofer 22APU) in solid oxide fuel cells (SOFCs). The thermo-mechanical stability of the glass/metal interface is evaluated experimentally as well as by using a finite element analysis (FEA) method. The sealing glass doped with 4 mol.% Nb2O5 shows the best thermo-mechanical stability, and the sealing couple of Crofer 22APU/glass/GDC (Gd0.2Ce0.8O1.9) remains intact after 50 thermal cycles. In addition, all sealing couples show good joining after being held at 750 °C for 1000 h. Moreover, the possible mechanism on the thermo-mechanical stability of sealing interface is investigated in terms of stress-based and energy-based perspectives.

In planar Solid Oxide Fuel Cells (SOFCs), the boron species volatilize from glass seals, and react with lanthanum-containing cathodes (i.e., La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 − δ , LSCF) to form LaBO 3 under cathodic polarization, which decomposes the perovskite structure and consequently decreases the electrochemical activity of cathode. In this study, Nb 2 O 5 and Gd 2 O 3 are added to an aluminoborosilicate glass to reduce the boron volatility from glass and the reaction between sealing glass and LSCF cathode. Both Nb 2 O 5 and Gd 2 O 3 doping increases the network connectivity, but Nb 2 O 5 doping enhances the [BO 3 ] → [BO 4 ] transition and reduces the boron volatility from glass seals, thus effectively suppressing the deposition and poisoning of boron contaminants on the LSCF cathode. However, an obvious degradation of the electrocatalytic activity of LSCF occurs in the presence of Gd 2 O 3 -doped glass. The relationship between glass structure and glass/cathode interaction has been established to provide useful information for designing stable sealing materials for SOFC applications.

A La 0.8 Sr 0.2 MnO 3 (LSM)/La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF) core–shell structured composite cathode of solid oxide fuel cells (SOFCs) has been fabricated by wet infiltration followed by a rapid sintering (RS) process. The RS is carried out by placing LSCF infiltrated LSM electrodes directly into a preheated furnace at 800 °C for 10 min and cooling down very quickly. The heating and cooling step takes about 20 s, substantially shorter than 10 h in the case of conventional sintering (CS) process. The results indicate the formation of a continuous and almost non-porous LSCF thin film on the LSM scaffold, forming a LSCF/LSM core–shell structure. Such RS-formed infiltrated LSCF–LSM cathodes show an electrode polarization resistance of 2.1 Ω cm 2 at 700 °C, substantially smaller than 88.2 Ω cm 2 of pristine LSM electrode. The core–shell structured LSCF–LSM electrodes also show good operating stability at 700 °C and 600 °C over 24–40 h.

Direct assembly is a newly developed technique in which a cobaltite-based perovskite (CBP) cathode can be directly applied to a barrier-layer-free Y2 O3 -ZrO2 (YSZ) electrolyte with no high-temperature pre-sintering steps. Solid oxide fuel cells (SOFCs) based on directly assembled CBPs such as La0.6 Sr0.4 Co0.2 Fe0.8 O3-δ show high performance initially but degrade rapidly under SOFC operation conditions at 750 °C owing to Sr segregation and accumulation at the electrode/electrolyte interface. Herein, the performance and interface of Sr-free CBPs such as LaCoO3-δ (LC) and Sm0.95 CoO3-δ (SmC) and their composite cathodes directly assembled on YSZ electrolyte was studied systematically. The LC electrode underwent performance degradation, most likely owing to cation demixing and accumulation of La on the YSZ electrolyte under polarization at 500 mA cm-2 and 750 °C. However, the performance and stability of LC electrodes could be substantially enhanced by the formation of LC-gadolinium-doped ceria (GDC) composite cathodes. Replacement of La by Sm increased the cell stability, and doping of 5 % Pd to form Sm0.95 Co0.95 Pd0.05 O3-δ (SmCPd) significantly improved the electrode activity. An anode-supported YSZ-electrolyte cell with a directly assembled SmCPd-GDC composite electrode exhibited a peak power density of 1.4 W cm-2 at 750 °C, and an excellent stability at 750 °C for over 240 h. The higher stability of SmC as compared to that of LC is most likely a result of the lower reactivity of SmC with YSZ. This study demonstrates the new opportunities in the design and development of intermediate-temperature SOFCs based on the directly assembled high-performance and durable Sr-free CBP cathodes.

Layered perovskite oxides are well known to possess significant electronic, magnetic and electrochemical properties. Herein, we highlight a novel layered perovskite PrBaMn1.5Fe0.5O5+δ (PBMFO) as electrodes of symmetrical solid oxide fuel cells (SSOFCs). The layered PBMFO shows high electrical conductivity of 112.5 and 7.4 S cm−1 at 800 °C in air and 5% H2/Ar, respectively. The single cell with PBMFO symmetric electrodes achieves peak power density of 0.54 W cm−2 at 800 °C using humidified hydrogen as fuel. Moreover, PBMFO electrodes demonstrate good redox stability and high coking tolerance against hydrocarbon fuel.

Bismuth based oxides have excellent ionic conductivity and fast oxygen surface kinetics and show promising potential as highly active electrode materials in solid oxide cells (SOCs) such as solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). However, the low melting temperature and high activity of bismuth based oxides severely limit their wide applications in SOCs. Herein, we successfully synthesized a 40 wt% Er0.4Bi1.6O3 decorated La0.76Sr0.19MnO3+δ (ESB–LSM) electrode via a new gelation method and directly assembled it on a Ni–yttria-stabilized zirconia (Ni–YSZ) cermet supported YSZ electrolyte cell without the conventional high temperature pre-sintering step. ESB decoration substantially enhances the electrocatalytic activity of the LSM electrode for the oxygen reduction/evolution reactions (ORR/OER). A YSZ electrolyte cell with the directly assembled ESB–LSM electrode exhibits a peak power density of 1.62 W cm−2 at 750 °C, significantly higher than 0.48 and 0.88 W cm−2 obtained on cells with a directly assembled pristine LSM and LSM–YSZ composite electrode, respectively. Most importantly the cells with the directly assembled ESB–LSM oxygen electrodes show excellent stability in SOFC, SOEC and reversible SOC operating modes for over 200 h. The present study demonstrates a significant advancement in the development of bismuth based oxide decorated high performance and stable oxygen electrodes for reversible SOCs.

Volatile organic compounds (VOCs) are perceived as serious pollutants due to their great threat to both environment and human health. Recovery and removal of VOCs is of great significance. Herein, novel MOF-199 derived porous carbon materials (MC-T-n) were prepared by using MOF-199 as precursor, glucose as additional carbon source and KOH as activator, and then characterized. Adsorption performance of MC-T-n materials for benzene vapor was investigated. Isotherms of MC-T-n samples towards benzene and water vapor were measured. The adsorption selectivities of benzene/water were estimated by DIH (difference of the isosteric heats) equation. Results indicated that BET surface area and pore volume of MC-T-n materials reached separately 2320 m2/g and 1.05 m3/g. Benzene adsorption capacity of MC-T-n materials reached as high as 12.8 mmol/g at 25 °C, outperforming MOF-199 and some conventional adsorbents. Moreover, MC-T-n materials presented type-V isotherms of water vapor, suggesting their excellent water resistance. The isosteric heats of benzene adsorption on MC-500-6 were much greater than that of water adsorption, leading to a preferential adsorption for C6H6 over H2O. The adsorption selectivity of C6H6/H2O on MC-500-6 reached up to 16.3 superior to some previously reported MOFs. Therefore, MC-500-6 was a promising candidate for VOC adsorption and seperation. This study provides a strong foundation for MOF derived porous carbons as adsorbents for VOC removal.

Reversible solid oxide cells (SOCs) are very efficient and clean for storage and regeneration of renewable electrical energy by switching between electrolysis and fuel cell modes. One of the most critical factors governing the efficiency and durability of SOCs technology is the stability of the interface between oxygen electrode and electrolyte, which is conventionally formed by sintering at a high temperature of ~1000–1250 ​°C, and which suffers from delamination problem, particularly for reversibly operated SOCs. On the other hand, our recent studies have shown that the electrode/electrolyte interface can be in situ formed by a direct assembly approach under the electrochemical polarization conditions at 800 ​°C and lower. The direct assembly approach provides opportunities for significantly simplifying the cell fabrication procedures without the doped ceria barrier layer, enabling the utilization of a variety of high-performance oxygen electrode materials on barrier layer–free yttria-stabilized zirconia (YSZ) electrolyte. Most importantly, the in situ polarization induced interface shows a promising potential as highly active and durable interface for reversible SOCs. The objective of this progress report is to take an overview of the origin and research progress of in situ fabrication of oxygen electrodes based on the direct assembly approach. The prospect of direct assembly approach in the development of effective SOCs and in the fundamental studies of electrode/electrolyte interface reactions is discussed.

Application of cobaltite-based electrodes such as La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) on Y2O3–ZrO2 (YSZ) electrolyte in solid oxide fuel cells (SOFCs) generally requires the use of a doped ceria barrier layer to prevent the interaction between LSCF and YSZ during sintering at high temperatures. In this paper, we report for the first time an in situ assembly approach to directly incorporate LSCF cathode to YSZ electrolyte without the use of a doped ceria barrier layer and without presintering at high temperatures. A Ni-YSZ anode-supported YSZ electrolyte cell with an in situ assembled LSCF electrode exhibits a peak power density of 1.72 W cm–2 at 750 °C. However, the cell performance degrades significantly at 500 mAcm–2 and 750 °C. The results indicate that cathodic polarization not only induces the formation of the interface but also accelerates the Sr segregation. The segregated Sr migrates to the LSCF electrode/YSZ electrolyte surface and forms an SrO layer. Using a Sr-free LaCoO3−δ composite cathode overco...

Biomass derived liquid fuels, bio-oil and biofuels, are attractive as a mix of future energy supply, and its combination with solid oxide fuel cells (SOFCs) would substantially enhance the energy conversion efficiency as compared to the conventional direct combustion. Here we present the preliminary results on the performance and operation stability of tubular SOFCs with conventional Ni-yttria-stabilized zirconia (Ni-YSZ) cermet anode and (La,Sr)MnO3-YSZ (LSM-YSZ) composite cathode running on mallee wood derived bio-oil and biofuels for the electricity generation. The tubular SOFCs show high performance for liquid bio-oil and biofuels, achieving a peak power density ~600 mW cm-2 at 800 °C, close to that produced in pure hydrogen. Significant carbon deposition due to the coke formation of bio-oil and biofuels was observed, leading to the blocking of the reaction sites and structural damage of the cell. However, the addition of CO2 dramatically suppresses the coke formation and significantly enhances the cell operating stability. The results show that it is feasible to directly use biomass derived liquid bio-oil and biofuels in tubular SOFCs for the onsite electricity generation. The cell performance and stability can be enhanced by further optimisation and modification of the composition and microstructure of the anodes of the tubular cells.

Gas diffusion limitation within Ni/YSZ cathode supports of solid oxide electrolysis cells (SOECs) during steam electrolysis has been reported in previous studies. In this study, a microchanneled cathode support has been prepared by a mesh-templating phase-inversion process to improve the gas diffusion. Numerous channels with one end open on the cathode surface cross the support and are stopped on the other side of the support by a porous layer which acts as a cathode functional layer. The integrated structure is ideal for achieving both fast gas diffusion and a long three-phase-boundary for performing the cathode reactions. Compared with conventional cathode supports, the microchanneled cathode support produced higher current densities at low steam concentrations of feed gas during steam electrolysis, which is attributed to the fast gas diffusion achieved within the channels. Therefore, the microchannel structure of cathode supports can increase hydrogen yield and steam utilization efficiency.

Inorganic-organic nanostructured hybrid membranes of polyethersuflone (PES)-polyvinylpyrrolidone (PVP) were prepared with mesoporous silica materials. Hollow mesoporous silica is synthesized via cationic surface-assistant etching method, while amino-functionalized hollow mesoporous silica and amino-functionalized mesoporous silica spheres were synthesized via post-grafting strategy. After the addition of mesoporous silica and amino-functionalized mesoporous silica into the matrix of PA doped PES-PVP composite membranes, all composite membranes show similar PA uptake. However, the proton conductivity of the composite membranes increases significantly with the substantial decrease in the activation energy for proton diffusion, especially for the amino-functionalized hollow mesoporous silica material. That reason is most likely due to the facilitated proton transportation in the ordered mesoporous channels via the hydrogen bond between the –NH2 groups and H3PO4. Cell performance also confirms the superiority of the addition of inorganic fillers in PES-PVP membrane, and the highest peak power density at 180 oC was 480 mW cm-2 for NH2-HMS based composite membrane, which is 92.7 % higher than that of PA doped PES-PVP composite membrane at the identical condition. The results show promising application of NH2-HMS based PES-PVP composite membrane for elevated temperature proton exchange membrane fuel cells. Figure 1

The understanding of surface chemistry changes on oxygen electrodes is critical for the development of reversible solid oxide fuel cell (RSOFC). Here, we report for the first time that the electrochemical potentials can drastically affect the surface composition and hence the electrochemical activity and stability of PrBaCo2 O5+δ (PBCO) electrodes. Anodic polarization degrades the activity of the PBCO electrode, whereas the cathodic bias could recover its performance. Alternating anodic/cathodic polarization for 180 h confirms this behavior. Microstructure and chemical analysis clearly show that anodic bias leads to the accumulation and segregation of insulating nanosized BaO on the electrode surface, whereas cathodic polarization depletes the surface species. Therefore, a mechanism based on the segregation and incorporation of BaO species under electrochemical potentials is considered to be responsible for the observed deactivation and recovery process, respectively.

Inductive impedance loop at low frequencies on electrochemical impedance spectroscopy curves is a common phenomenon in electrochemical reactions such as fuel cells. Here, we study the occurrence of low frequency inductive impedance loops and their evolution for the oxygen reduction reaction on Gd 0.2 Ce 0.8 O 1.9 infiltrated La 0.8 Sr 0.2 MnO 3 (GDC-LSM), GDC infiltrated Pt (GDC-Pt) and mixed ionic and electronic conducting (MIEC) La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) cathodes under solid oxide fuel cells (SOFCs) operation conditions. The incorporation of GDC nanoparticles (NPs) substantially enhances the electrochemical activity of LSM and Pt electrodes with the concomitant occurrence of an inductive impedance loop at low frequencies. However, the low frequency impedance loop disappears for the GDC-LSM with GDC NPs larger than 41 nm or after polarization at 200 mA cm − 2 for more than 60 min. In the case of LSCF electrode the low frequency inductive loop transfers to capacitive arc after polarization for 30 min. The occurrence of low frequency inductive loops is closely related to the electrode electrocatalytic activity and microstructure and is primarily determined by the ability of the electrode materials to supply atomic oxygen for the reaction at the interface. A mechanism of competitive atomic oxygen supply and dissociative oxygen adsorption and diffusion is proposed for the occurrence of the inductive loops at low frequencies for the O 2 reduction reaction of SOFCs.

In this communication, cobaltite-based perovskite (CBP) cathodes are directly applied on the yttria-stabilized zirconia (YSZ) electrolyte via an in situ assembly process without the addition of a doped ceria interlayer and pre-sintering at high temperatures. The results demonstrate for the first time that a CBP electrode/YSZ electrolyte interface can be formed in situ under cathodic polarization at a solid oxide fuel cell (SOFC) operating temperature of 750 °C. Nevertheless, the performance of cells with Sr-containing CBP cathodes deteriorates due to the surface segregation of Sr species and formation of a Sr-rich reaction layer at the interface. However, the stability and power density of cells with in situ assembled CBP cathodes can be further enhanced by B-site doping or by using a Sr-free CBP. The direct application of CBPs on the YSZ electrolyte revolutionizes the design of intermediate temperature SOFCs.

It is important to find alternative membranes to the state-of-the-art polybenzimidazole based high temperature proton exchange membranes with high proton conductivity at elevated temperature but with simple synthesis procedures. In this work, inorganic–organic nanostructured hybrid membranes are developed based on a polyethersulfone–polyvinylpyrrolidone (PES–PVP) polymeric matrix with hollow mesoporous silica (HMS), amino-functionalized hollow mesoporous silica (NH2-HMS) and amino-functionalized mesoporous silica (NH2-meso-silica). The composite membranes show a significant increase in proton conductivity and a decrease in the activation energy for proton diffusion in comparison with the phosphoric acid (H3PO4, PA) doped PES–PVP membrane. And the composite membrane with NH2-HMS shows the best performance under the conditions in this study, achieving the highest proton conductivity of 1.52 × 10−1 S cm−1 and highest peak power density of 480 mW cm−2 at 180 °C under anhydrous conditions, which is 92.7% higher than that of the PA doped PES–PVP membrane at identical conditions. Such enhancement results from the facilitated proton transportation in the ordered mesoporous channels via the hydrogen bond between the –NH2 groups and H3PO4. The high water retention capability of silica materials with a hollow structure also contributes to the decrease of the activation of proton diffusion. Consequently, the results show promising potential of the NH2-HMS based PES–PVP composite membrane for the elevated temperature proton exchange membrane fuel cells.

The effect of boron species from borosilicate glass sealant on the electrocatalytic activity and microstructure of La0.8Sr0.2MnO3 (LSM) oxygen electrodes is studied for the first time under accelerated solid oxide electrolysis cell (SOEC) operation conditions at 800 °C. The presence of volatile boron species has remarkable detrimental effect on the electrochemical activity of LSM oxygen electrode for the O2 evolution reaction (OER). After polarization at 200 mA cm−2 for 2 h, the electrode polarization and ohmic resistances increase rapidly from ∼40 and 1.2 Ω cm2 to 614 and 33 Ω cm2, respectively. Under the anodic polarization conditions, there is an accelerated Sr segregation and boron deposition preferentially occurs at the electrode/electrolyte interface, forming lanthanum borates and manganese oxide. Boron deposition and reaction is driven to the interface region due to the increased activity and energetics of lanthanum at LSM lattice sites at the electrode/electrolyte interface under anodic polarization conditions, accelerating the disintegration and delamination of the LSM electrode. The results indicate the potential detrimental effect of volatile boron on the electrochemical activity and stability of LSM oxygen electrodes of solid oxide electrolyzers.

This project is supported by the National Natural Science Foundation of China (project number: 51472099) and the Australian Research Council under the Discovery Project Scheme (project number: DP150102025 & DP150102044) Cobaltite-based double perovskite oxides with high electrocatalytic activity and conductivity have been developed as high-performance cathode alternatives for solid oxide fuel cells (SOFCs). However, the use of cobaltite-based double perovskites on Y2O3 stabilized ZrO2 (YSZ)-based SOFCs requires the application of a doped ceria barrier layer. This is due to their poor chemical and physical compatibility with the YSZ electrolyte during high-temperature sintering and fabrication processes. Here we report a viable approach to in operando assemble double perovskites such as PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF), on YSZ electrolyte and thus effectively form an electrode/electrolyte interface without high-temperature processing. The electrochemical performance of the in situ assembled PBSCF cathode is comparable to that of the cathode prepared by conventional methods. A single cell with an in situ assembled PBSCF–GDC (Gd-doped ceria) cathode achieved a peak power density (PPD) of 1.37 W cm−2 at 750 °C and exhibited a high stability at 500 mA cm−2 and 750 °C for 100 h. Surface and cross-sectional microstructure analysis offer solid evidence that the PBSCF–GDC cathode/YSZ electrolyte interface was formed by electrochemical polarization. This work offers new opportunities to effectively and effortlessly use high-performance double perovskite cathodes in commercial SOFCs. Postprint