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Compared to conventional Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF) and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF), BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ (BCFZY) with special surface species and structure can exhibit a distinctive compromise between the redox activity and cell stability. The X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD) and infrared spectrum (IR) results suggest that besides the oxygen species of BSCF and LSCF, the OH-related species can be detected on BCFZY, which can play a promoting role in oxygen catalysis activity. The O2− -conducting solid oxide fuel cell (SOFC) with BCFZY cathode shows the superior power densities at intermediate temperatures (750-650 °C), which are 1.2–1.6 times than those of BSCF cell, and 1.8–2.1 times than those of LSCF cell. Distribution of relaxation times (DRT) analysis on three symmetric cells and three single cells reveal that BCFZY cathode shows superior oxygen adsorption and dissociation, which can be ascribed to the peculiar OH-related species and multiscale structure on the surface. The cell with BCFZY cathode can remain the stable performance during the discharge testing at 650 °C for 240 h, indicating a reliable surface state to promote both oxygen catalysis activity as well as the performance stability for O2− -conducting SOFC. • BCFZY demonstrates considerable activity vs BSCF and LSCF on O2--conducting SOFC. • BCFZY cell achieves high power density (1.99–1.40 W cm−2) at 750-650 °C. • BCFZY cathode exhibits superior oxygen exchange processes on surface. • The special surface state of BCFZY cathode improves O 2 catalysis and stability. [ABSTRACT FROM AUTHOR]

In this paper, fuel composition and efficiency of solid oxide fuel cell with different methanol pretreating technologies are investigated. High concentrations of H2 and CO can be produced by methanol pretreatment at high temperature, whereas high concentration of methane can be produced at low temperature under the thermodynamic equilibrium condition. For steam reforming of methanol, high cell efficiency can be obtained, whereas for partial oxidation of methanol, the cell efficiency decreases most obviously compared with other pretreating technologies with the increase of O/C ratio. When the O/C ratio is 1.5, the cell efficiencies are 55.89% for steam reforming of methanol, 50.83% for autothermal reforming of methanol, and 45.77% for partial oxidation of methanol at 80% equivalent fuel utilization and 1073 K. When the O/C ratio increases to 2.5, the cell efficiency decreases slowly to 52.01% for steam reforming of methanol, whereas rapidly to 21.68% for partial oxidation of methanol at 80% equivalent fuel utilization and 1073 K. According to the calculated results under the thermodynamic equilibrium condition, suitable pretreating technology and O/C ratio for methanol pretreatment can be selected for the operation of solid oxide fuel cell, which can lead to the high efficiency and good stability of solid oxide fuel cell. [ABSTRACT FROM AUTHOR]

The composite perovskites are promising low/intermediate-temperature solid oxide fuel cell (LT/IT-SOFC) cathode materials, which can combine the complementary advantages of multi-components. Here, novel liquid self-assembly (SA) is compared with nanosolid mechanical-mixing (MM) for the high-performance nanostructured composite. The same composition of the active BaCo 0.96 Zr 0.04 O 2.6+δ (12hBC, 38 mol%) with the stable BaZr 0.82 Co 0.18 O 3-δ (BZC, 62 mol%) is designed to compare the effects of different syntheses on composite properties. The BZC-12hBC (SA) can achieve molecular-level contact of multiple phases, which exhibits superior electrical conductivity, surface and heterointerface activity to those of BZC-12hBC (MM). When further applied on LT/IT-SOFC, the cell with BZC-12hBC (SA) cathode achieves the remarkable peak power densities of 2.06–0.24 W cm−2 at 700–500 °C, while the cell with BZC-12hBC (MM) cathode only exhibits 0.63–0.11 W cm−2. The electrochemical analysis reveals that BZC-12hBC (SA) cathode possesses better oxygen dissociative adsorption and species transportation than those of the BZC-12hBC (MM) cathode. • A self-assembly (SA) method is compared with mechanical mixing for composite. • The SA achieves nanostructured composite of superior oxygen redox properties to MM. • Power density of cell with cathode (SA) is almost 3 times of that with cathode (MM). • The composite (SA) has superior adsorption and transport activity to composite (MM). [ABSTRACT FROM AUTHOR]

Assembling multiple perovskites with complementary properties is a promising strategy to achieve high-performance cathodes for low/intermediate-temperature solid oxide fuel cell (LT/IT-SOFC). In this work, self-assembling perovskites of cubic BaZr 0.82 Co 0.18 O 3-δ (cub-BZC) and hexagonal BaCo 0.96 Zr 0.04 O 2.6+δ (12H-BC) at the nanoscale can be realized in novel designed nanocomposites with nominal composition of BaCo 1-x Zr x O 3-δ (x = 0.8–0.2), which can possess congenital compatibility, improved thermal expansion coefficients and electrical conductivity. The relative contents of cubic and hexagonal phases are significantly correlated with the zirconium content (x). Therein, BaCo 1-x Zr x O 3-δ nanocomposites exhibit relatively low content differences among perovskite phases when x = 0.4 (cubic/hexagonal = 62:38) and x = 0.2 (hexagonal/cubic = 69:31) nanocomposites, which can form more extensive heterointerfaces for promoting oxygen adsorption, dissociation and reduction reaction. When further applied as cathode, the cell with BaCo 1-x Zr x O 3-δ nanocomposites achieve 2265–598 mW cm−2 (800–600 °C) when x = 0.2 as a promising IT-SOFC cathode, and 315−148 mW cm−2 (550–500 °C) when x = 0.4 as a promising LT-SOFC cathode. [ABSTRACT FROM AUTHOR]

• Two (Ba, Sr/Sm)(Co, Zr)O 3-δ composites are prepared via a smart co-assembled method. • Two composite show good thermal properties and nanostructure to extend active area. • Two co-assembled composites show excellent cell performance as IT-SOFC cathodes. • The BSmCZ cell shows better oxygen catalysis activity at the intermediate temp range. The cobalt-based perovskites are the most common solid oxide fuel cell (SOFC) cathode materials, which generally have the issues of thermal compatibility and performance at the reducing temperature. In this study, two Ba 0.5 (Sm/Sr) 0.5 Co 0.8 Zr 0.2 O 3-δ (BSmCZ/BSrCZ) perovskite composites were synthesized using a smart co-assembled method, which were primarily composed of cubic doped-BaZrO 3 and hexagonal doped-BaCoO 3 perovskites. Both BSmCZ and BSrCZ composites exhibited more suited thermal expansion coefficient (12.8 × 10-6 and 13.9 × 10-6 K−1) to the electrolyte, nanostructure with extensive heterointerfaces and excellent cathode|electrolyte interfaces. Compared to BSrCZ composite, the BSmCZ composite possessed a relatively higher content (65 %) of activated oxygen species and higher electrical conductivity (70.7 S cm−1). The cells with two composite cathodes could achieve the remarkable maximum power density, especially for BSmCZ composite cathode of 2.00–1.11 W∙cm−2 at 800–650 °C. The electrochemical analysis revealed that the BSmCZ composite cathode demonstrated the enhanced surficial oxygen catalysis processes, which could benefit from the active oxygen species and heterointerface. [ABSTRACT FROM AUTHOR]

A new series of perovskite composites with nominal compositions of Sr 0.8 La 0.2 Co 1-x Zr x O 3-δ (x = 0.2–0.8) are proposed and synthesized via one-pot in-situ self-assembly method, of which the most optimum composite is further investigated as intermediate-temperature solid oxide fuel cell (IT-SOFC) cathode. When the zirconium content (x) is equal to 0.2, the mixed ionic and electronic conducting Sr 0.74 La 0.26 CoO 3-δ (SLC) and ionic conducting SrZr 0.79 Co 0.21 O 3-δ (SZC) are incorporated as nanocomposite particles (100 nm) on the well-connected SLC microparticles (200–500 nm). This hierarchical structure is favorable for charge transport, oxygen reduction and gas diffusion. Besides, 74 wt% of SLC self-assembled with 26 wt% of SZC in nanoscale can effectively tailor the thermal expansion coefficient (18.6 × 10−6 K−1), which makes Sr 0.8 La 0.2 Co 0.8 Zr 0.2 O 3-δ (SLC-SZC) composite cathode much matchable with the YSZ and GDC electrolytes (10.8 × 10−6 K−1 and 12.8 × 10−6 K−1). The electrical conductivity of SLC-SZC composite attains 170-107 S cm−1 at 375–700 °C. The single cell with SLC-SZC composite cathode achieves the maximum power density of 1739 mW cm−2 at 650 °C, superior to cells with pure Sr 0.8 La 0.2 CoO 3-δ cathode. The impedance analysis verifies that oxygen adsorption and dissociation processes of the SLC-SZC composite cathode can be enhanced by its extensive surface area of the hierarchical structure and extensive heterointerface of the nanocomposite. [Display omitted] • The self-assembly occurs on novel perovskite Sr 0.8 La 0.2 Co 1-x Zr x O 3-δ composites. • Sr 0.74 La 0.26 CoO 3-δ (SLC) and SrZr 0.79 Co 0.21 O 3-δ nanoparticle is embed in SLC backbone. • Sr 0.8 La 0.2 Zr 0.2 Co 0.8 O 3-δ (SLC-SZC) exhibits extensive surface and heterointerface. • The SLC-SZC composite cathode shows active catalysis on oxygen reduction reaction. • Single cell with SLC-SZC composite cathode shows excellent output performance. [ABSTRACT FROM AUTHOR]

In this study, cost-effective cathode materials with high catalysis activity for oxygen reduction reaction (ORR) are proposed for use in intermediate-temperature solid oxide fuel cells. Cobalt-free Ba 0.5 A 0.5 Fe 0.8 Zr 0.2 O 3-δ (A=Sr2+/Sm3+, BSrFZ/BSmFZ) composites were synthesised using a smart self-assembled method that primarily utilised doped-BaZrO 3 and doped-BaFeO 3 cubic perovskites. The BSrFZ composite possesses a higher doped-BaFeO 3 (75 wt%) content, which facilitates the formation of oxygen vacancies and ORR catalysis. The BSmFZ composite exhibits a relatively higher content of doped-BaZrO 3 (31 wt%) than that of the BSrFZ composite, which is more suited to the electrolyte and improves the thermal expansion coefficient (16.0 × 10−6 K−1). Both composite cathodes exhibit nano- and micro-particles with extensive heterointerfaces and excellent cathode|electrolyte interfaces, which can assist the surface catalysis and oxygen species transport. The cell with a BSrFZ composite cathode achieved a higher maximum power density of 1.64 W cm−2 at 750 °C compared to that of the cell with a BSmFZ composite cathode that had a maximum power density of 0.99 W cm−2. The electrochemical analysis revealed that the BSrFZ composite cathode demonstrated enhanced oxygen adsorption dissociation and oxygen species reduction processes, which benefit from its enriched oxygen vacancies and high surface and heterointerface activities. [ABSTRACT FROM AUTHOR]

The cobalt/iron-containing perovskites are the most promising cathodes for the intermediate-temperature solid oxide fuel cell (IT-SOFC). However, these cathodes are generally not directly applied on the currently available commercial yttria-stabilized zirconia (YSZ) electrolyte due to the issues of over-firing, harmful reaction and thermal incompatibility. BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ (BCFZY) which contains both zirconium and yttrium ions can theoretically be more compatible with the YSZ electrolyte. This paper focuses on the surficial and interfacial properties of BCFZY directly prepared with YSZ under different conditions. The surface of BCFZY by the glycine-nitrate process (GNP) can form the nanoparticles in contrast to that by solid-state reaction (SSR). The peak power density of the cell with BCFZY-GNP cathode directly on YSZ electrolyte can reach 1250 mW cm−2 at 750 °C, which is hardly achieved on the reported traditional cobalt/iron-containing cathodes. It is proved that BCFZY-GNP cathode fired at 900 °C can show more distinct nanoparticles with extensive specific surface area and better BCFZY|YSZ interface, which can promote both oxygen exchange and ion incorporation processes. • The BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ (BCFZY) can form nanoparticles to extend surface area. • BCFZY cathode shows a well-connected interface when directly applied on YSZ. • BCFZY cathode fired at 900 °C shows both low surficial and interfacial resistances. • The single cell exhibits the excellent performance of 1250 mW cm−2 at 750 °C. [ABSTRACT FROM AUTHOR]

Natural gas is a cheap and abundant fuel for solid oxide fuel cell (SOFC), generally integrating the SOFC system with methane pre-treating system for improving the stability of SOFC. In this paper, the accurate effects of methane processing strategy on fuel composition, electrical efficiency and thermal efficiency of SOFC are investigated based on the thermodynamic equilibrium. Steam reforming of methane is an endothermic process and can produce 3 mol of H 2 and 1 mol of CO from 1 mol of methane, and thus the electrical efficiency of SOFC is high at the same O/C ratio and equivalent fuel utilization, whereas the thermal efficiency is low. On the contrary, partial oxidation of methane is an exothermal process and only produces 2 mol of H 2 and 1 mol of CO from 1 mol of methane, and thus the electrical efficiency of SOFC is low at the same O/C ratio and equivalent fuel utilization, whereas the thermal efficiency is high. When the O/C ratio is 1.5, the electrical efficiency of SOFC is 55.3% for steam reforming of methane, while 32.7% for partial oxidation of methane. High electrical efficiency of SOFC can be achieved and carbon deposition can be depressed by selecting suitable O/C ratio from methane pretreatment according to the accurate calculation and analysis of effects of different methane processing strategies on the electrical efficiency and thermal efficiency of SOFC. [Display omitted] • Methane processing strategy is investigated based on the thermodynamic equilibrium. • Fuel composition is calculated under the thermodynamic equilibrium condition. • Suitable O/C ratio from methane pretreatment can depress carbon deposition. • Effects of methane processing strategy on electrical efficiency are investigated. • Effects of methane processing strategy on thermal efficiency are investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Ni-based anode coated by perovskite STMN -Ni is fabricated for SOFC. • STMN-Ni coating can enhance the electrode activity and sulfur resistance of Ni anode. • The electrochemical performance cell can be attributed to the charge transfer and O2– transport. • Coating is able to reduce the sulfur adsorption and promote the oxidation of sulfur. A Ni-based anode coated by SrTi 0.5 Mo 0.2 Ni 0.3-x O 3−δ with nano-nickel is prepared by wet impregnation. The effects of the loading amounts of SrTi 0.5 Mo 0.2 Ni 0.3-x O 3−δ with nano-nickel coating on the cell performance are investigated. XRD characterization shows that SrTi 0.5 Mo 0.2 Ni 0.3-x O 3−δ perovskite and NiO phase are in-situ formed. SEM images display that SrTi 0.5 Mo 0.2 Ni 0.3-x O 3−δ perovskite with nano-nickel covers the substrate NiO. The construction of SrTi 0.5 Mo 0.2 Ni 0.3-x O 3−δ perovskite with nano-nickel coating has remarkable influence on the conductivity of Ni - based anode. Electrochemical performance test indicates that SrTi 0.5 Mo 0.2 Ni 0.3-x O 3−δ perovskite with nano-nickel coating can enhance the electrode activity and reduce the impedance. Additionally, the fuel cell with Ni - based anode coated by SrTi 0.5 Mo 0.2 Ni 0.3-x O 3−δ perovskite with nano-nickel exhibits more favorable electrochemical stability than the conventional Ni based anode in 100 ppm H 2 S/H 2. In short, the Ni based anode with SrTi 0.5 Mo 0.2 Ni 0.3-x O 3−δ and Ni composite coating is a feasible material candidate for the electrode of high-performance solid oxide fuel cells. [ABSTRACT FROM AUTHOR]