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Co-improving the structural stability and electrocatalytic activity of anode materials is a major challenge for the development of solid oxide fuel cells (SOFCs). Herein, a novel anode material Sr2Fe1.5Mo0.4Ti0.1O6−δ (SFMT) is designed and prepared by using Ti to replace Mo of Sr2Fe1.5Mo0.5O6−δ (SFM). Ti doping effectively enhances the ability of SFM to resist H2S corrosion and SFMT maintains the desired perovskite structure after being exposed to H2S (1000 ppm). Moreover, the partial replacement of Mo5+/Mo6+ by Ti4+ ions can also improve the concentration of oxygen vacancies and enhance the oxygen ion surface exchange and bulk diffusion capabilities. The SFMT-based SOFC delivers an excellent power output in H2 containing 500 ppm H2S and stably operates for a long time (>50 h), resulting in a maximum power density of 0.71 W cm−2 at 800 °C. The current study presents a promising material design strategy for developing high-performance SOFC anodes. [ABSTRACT FROM AUTHOR]

Effective utilization of carbonaceous fuels is essential to address the economic and environmental challenges in the future. Direct carbon solid oxide fuel cells (DCSOFCs) offer a promising solution, but their performance is hindered by the sluggish anode processes and poor stability. Herein, a novel layered perovskite, (PrBa)0.95Fe1.6Ni0.2Nb0.2O5+δ (PBFNN), is developed as a highly effective anode material for DCSOFCs. FeNi3 nanoparticles on the perovskite substrate are in situ exsolved under the reduction of carbon, and the resulting alloy–perovskite interfaces can promote efficient reverse Boudouard reaction (RBR) by the optimized CO2 capture and RBR activation. Therefore, the carbon fuel can be efficiently converted into CO because of the highly active RBR on the surface of the PBFNN anode, which further promotes the electrochemical oxidation of CO, leading to enhanced electrochemical performance of the anode. An electrolyte-supported DCSOFC employing the PBFNN anode yields superior performances but using additive-free carbon fuels, and delivers a peak power density of 605.1 mW cm−2 at 800 °C and superior stability over 120 h at 750 °C. Our work highlights that PBFNN is a high-performance and robust alternative perovskite anode for DCSOFCs. [ABSTRACT FROM AUTHOR]

Elevating the sluggish oxygen reduction reaction (ORR) activity of the cathode material is crucial to the development and widespread application of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, a novel SOFC cathode, with superior ORR activity, is designed by incorporating F anions at O-sites of a double perovskite oxide (Sr2Fe1.5Mo0.5O6−δ, SFM). The resulting F-doped SFM cathode (Sr2Fe1.5Mo0.5O6−x−δFx, SFMF, x = 0, 0.1, 0.2 and 0.3) exhibits improved crystal structure symmetry and enhanced electrocatalytic activity for the ORR. At 800 °C, the polarization resistance of F-doped SFM is significantly decreased to 0.072 Ω cm2, which can be ascribed to the enhanced oxygen reduction capacity. Moreover, F-doping reduces the metal–oxygen bond energy and accelerates the transportation of O-ions during the electrochemical process, resulting in significantly enhanced ORR activity. [ABSTRACT FROM AUTHOR]

Protonic ceramic fuel cells (PCFCs) have interesting potential to efficiently produce electrical power from fuels in a low-temperature range (＜650 °C). However, the sluggish activity of the oxygen reduction reaction is one of the greatest obstacles to the development of PCFCs. Single-phase triple-conducting (e−/O2−/H+) oxides are considered to be the most promising candidates for highly active PCFC cathodes because they can extend the electrochemically active sites to the entire cathode surface. Here, A-site deficiency of perovskite is introduced to tune the triple-conducting properties, which can stimulate the generation of oxygen vacancies and increase the oxygen-ion bulk diffusion and proton hydration kinetics. The so-obtained A-site-deficient perovskite oxides, BaxCo0.4Fe0.4Zr0.1Y0.1O3−δ (x = 1, 0.95, 0.9), exhibit area specific resistance values of 1.61, 0.94, and 0.52 Ω cm2 for BaCo0.4Fe0.4Zr0.1Y0.1O3−δ, Ba0.95Co0.4Fe0.4Zr0.1Y0.1O3−δ, and Ba0.9Co0.4Fe0.4Zr0.1Y0.1O3−δ, respectively, at 500 °C in wet air (pH2O = 0.1 atm). Peak power densities of 797.47, 668.64, 548.07, and 376.27 mW cm−2 are obtained from the PCFC with the Ba0.9Co0.4Fe0.4Zr0.1Y0.1O3−δ cathode at 650, 600, 550 and 500 °C, respectively. Such remarkable performance demonstrates that introducing A-site deficiency is an effective strategy to enhance the triple-conducting properties of perovskite oxides for the high-activity cathode of PCFCs. [ABSTRACT FROM AUTHOR]

In this study, Nb doped double perovskite oxide (Sr 2 Fe 1.4 Nb 0.1 Mo 0.5 O 6-δ) is prepared and tested as symmetrical electrodes for intermediate temperature solid oxide fuel cells. X-ray diffraction demonstrates that Sr 2 Fe 1.4 Nb 0.1 Mo 0.5 O 6-δ maintains more stable cubic perovskite phase structure than its raw material (Sr 2 Fe 1.5 Mo 0.5 O 6-δ) under reducing atmosphere. X-ray photoelectron spectrometry shows that Nb doping significantly enhances bond strength of Fe O Fe(Nb) so that Fe ion maintains more stable oxidation states after reducing. At 600 °C, Nb doping also increases the conductivity from 17.62 to 27.61 cm−1 in air and from 11.11 S cm−1 to 15.86 S cm−1 in wet hydrogen (∼3% H 2 O). Furthermore, Sr 2 Fe 1.4 Nb 0.1 Mo 0.5 O 6-δ exhibits enhanced electrochemical performances in terms of lower polarization resistance under both oxidizing and reducing atmospheres. Peak power densities of 364.93 and 531.49 mW cm−2 at 750 and 800 °C are obtained based on a single symmetrical cell with Sr 2 Fe 1.4 Nb 0.1 Mo 0.5 O 6-δ electrode, which also shows excellent redox stabilities. All of these results confirm that Sr 2 Fe 1.4 Nb 0.1 Mo 0.5 O 6-δ electrode has promising prospects for the symmetrical intermediate temperature solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

Perovskite oxide Sr2Fe1.3Cu0.2Mo0.5O6−δ (SFCM) is prepared and evaluated as a novel cathode material for solid oxide electrolytic cells (SOECs). At 750 °C, the interfacial polarization resistance value decreased from 1.834 to 1.125 Ω cm2 and the SFCM cathode exhibited excellent stability for 100 h, without any significant attenuation, at an electrolytic voltage of 1.5 V. [ABSTRACT FROM AUTHOR]

High-temperature steam electrolysis (HTSE) via solid oxide electrolysis cell (SOEC) enables realizing hydrogen production efficiently and eco-friendly due to the high-temperature operation. To cater to the practical application and enable flexible connection to the unpredictable and intermittent renewable sources, the ability to multiply and rapidly start up means vital for these SOEC devices. Herein, one novel structural tubular SOEC has been proposed and fabricated, adopting YSZ and Ni-doped Sr(Ti, Fe)O 3 as the inert support and fuel electrode, respectively, replacing the traditional Ni-cermet. The as-fabricated tubular cell revealed ability to electrolyze steam under hydrogen-free atmosphere, achieving 0.79 and 1.36 A at the applied voltage of 1.3 V and 1.6 V at 800 °C. Moreover, not only the structure but also the performance showed no obvious degradation during the ten-time start-pause cycle test over 80 h. This work demonstrates the great potential of SOEC devices in the future power-to-hydrogen technology. [ABSTRACT FROM AUTHOR]

In this paper, Sr 2 Fe 1.5 Mo 0.4 Nb 0.1 O 6−δ (SFMNb)−xSm 0.2 Ce 0.8 O 2−δ (SDC) (x = 0, 20, 30, 40, 50 wt%) composite cathode materials were synthesized by a one-pot combustion method to improve the electrochemical performance of SFMNb cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). The fabrication of composite cathodes by adding SDC to SFMNb is conducive to providing extended electrochemical reaction zones for oxygen reduction reactions (ORR). X-ray diffraction (XRD) demonstrates that SFMNb is chemically compatible with SDC electrolytes at temperature up to 1100 °C. Scanning electron microscope (SEM) indicates that the SFMNb-SDC composite cathodes have a porous network nanostructure as well as the single phase SFMNb. The conductivity and thermal expansion coefficient of the composite cathodes decrease with the increased content of SDC, while the electrochemical impedance spectra (EIS) exhibits that SFMNb-40SDC composite cathode has optimal electrochemical performance with low polarization resistance ( R p ) on the La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3 electrolyte. The R p of the SFMNb-40SDC composite cathode is about 0.047 Ω cm 2 at 800 °C in air. A single cell with SFMNb-40SDC cathode also displays favorable discharge performance, whose maximum power density is 1.22 W cm −2 at 800 °C. All results indicate that SFMNb-40SDC composite material is a promising cathode candidate for IT-SOFCs. [ABSTRACT FROM AUTHOR]

Solid oxide electrolysis cell (SOEC) has great application prospects in the fields of renewable energy storage, CO 2 capture and utilization. One of the key factors hindering the development of SOEC is the lack of suitable cathode materials. In this study, we designed and developed a kind of new micro-nano heterostructure materials Co@Sr 1.95 Fe 1.4 Co 0.1 Mo 0.4 Ti 0.1 O 6-δ (Co@SFCMT), Co nanoparticles uniformly distributed on the SFCMT matrix and provided rich electric catalytic active sites, SFCMT showed excellent oxygen ion transport performance. The synergistic effect of Co nanoparticles and Sr 1.95 Fe 1.4 Co 0.1 Mo 0.4 Ti 0.1 O 6-δ (SFCMT) increased the rate of CO 2 reduction reaction (CO 2 RR). At 1.8 V and 800 °C, the maximum electrolytic current density of the cell with Co@SFCMT as the cathode reached 2.57 A cm−2. In addition, Co@SFCMT showed good stability at 1.5 V and 750 °C, with no performance decay even after 200 h of continuous operation. The micro-nano heterostructure design strategy of perovskite oxides will not only open new avenues for designing SOEC electrodes, but also be expected to promote the development of other energy storage and conversion systems. • A novel heterostructure cathode material for solid oxide electrolysis cell was prepared. • The Co@Sr 1.95 Fe 1.4 Co 0.1 Mo 0.4 Ti 0.1 O 6-δ material exhibited high activity and stability. • Structural stability of the material was regulated by introducing Ti. • No performance decay was observed after 200 h of operation. [ABSTRACT FROM AUTHOR]

Flash sintering is novel, innovative, and promising technique for achieving highly dense ceramic materials at low furnace temperature and short sintering time. Herein, flash sintering process was studied by reducing furnace temperature while the electric field applied to samples was kept constant. Further, 8 mol% yttria-stabilized zirconia (8YSZ) samples were sintered by current-limiting flash sintering mode during the occurrence of this flash sintering process. Results showed that the lower the furnace temperature, the longer the time for the onset of flash sintering. However, temperature threshold was observed under certain electric field. Resulting flash sintered 8YSZ samples were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). SEM images exhibited well-dense microstructures with small grain size. EIS results indicated that the values of conductivity of all 8YSZ samples flash sintered at different furnace temperatures were almost similar, and the conductivity of 8YSZ flash sintered at 565 °C reached 0.056 S cm −1 at 850 °C under the electric field of 300 V cm −1 , which is adequate for solid oxide fuel cells application. [ABSTRACT FROM AUTHOR]

Efficient and direct utilization of coal-based fuels is the developmental direction of direct carbon solid oxide fuel cells (DCSOFCs), but their performance is hindered by poor catalytic activity and contaminant poisoning of anode materials. Herein, a Ti-doped double perovskite oxide Sr 2 Fe 1.5 Mo 0.4 Ti 0.1 O 6-δ (SFMT) was developed as the coal-based DCSOFC anode to improve its catalytic activity and resistance to sulfur poisoning. X-ray photoelectron spectroscopy confirms that SFMT shows abundant oxygen vacancy concentration under reducing atmosphere. The as-fabricated DCSOFC with the SFMT anode delivers a maximum power density of 506.5 mW cm−2 at 800 °C when using bituminous coal as the fuel. Electrochemical impedance spectroscopy reveals that Ti doping can effectively promote electrochemical processes on the anode side. Both thermogravimetric analysis and CO temperature-programmed desorption demonstrate that the performance improvement of SFMT is ascribed to its promoted catalytic activity in coal gasification and its increased CO adsorption capacity. The operational period of this coal-based DCSOFC increases from 2 to 10 h after Ti doping, which can be explained by the enhanced structural stability of SFMT under a sulfur-containing environment. Our work may provide some new insight on the design of high-activity anode materials and the understanding of anode reaction mechanisms for coal-based DCSOFCs. [Display omitted] • Sr 2 Fe 1.5 Mo 0.4 Ti 0.1 O 6-δ (SFMT) was designed for a high-efficiency DCSOFC anode. • SFMT shows a stable phase structure under a sulfur-containing atmosphere. • Ti-doping promotes the electrochemical oxidation of C/CO and the adsorption of CO. • SFMT-based DCSOFC reaches a power density of 506.5 mW cm−2 with coal as fuel. [ABSTRACT FROM AUTHOR]

Solid oxide electrolytic cells (SOEC) have great potential in CO 2 conversion and energy storage. However, commercial application of SOEC is still challenging due to the sluggish rate of CO 2 electrochemical reduction caused by the arduous activation and limited CO 2 adsorption on cathode surface. In this study, synergetic regulation strategy on intrinsic catalysis activity and surface amelioration is proposed to improve the CO 2 adsorption capacity and increase the adsorption sites. This strategy is demonstrated in a Cu-doped three-dimensional (3D) porous Sr 2 Fe 1 · 3 Cu 0 · 2 Mo 0 · 5 O 6−δ (SFCuM) nanotube cathode. The results indicate that SFCuM nanotube shows more oxygen vacancies and excellent oxygen ion conduction. At the same time, the nanostructure provides a larger three-phase reaction interface and more reaction sites for CO 2 reduction reaction (CO 2 RR). Benefiting from these merits, the maximum electrolytic current density of the designed SFCuM electrode can be improved to 1.68 A cm−2 at 750 °C and the related polarization resistance can be lowered to 0.59 Ω cm2. In addition, the porous SFCuM nanotube electrode also showed good stability at a constant electrolytic voltage of 1.5 V, with no performance decay during continuous 200-h operation. Such a synergetic regulation strategy may provide some new insight on catalyst design and modification for high-activity CO 2 RR electrode. [Display omitted] • 3D porous SFCuM nanotube cathode has been constructed for efficient CO 2 RR. • SFCuM exhibits more oxygen vacancies and excellent oxygen ion conduction. • SFCuM nanotube provides more reaction sites for the CO 2 adsorption. • The maximum electrolytic current density can be improved to 1.68 A cm−2 at 750 °C. [ABSTRACT FROM AUTHOR]

The development of cathode materials, with high catalytic activity toward oxygen reduction reaction (ORR), structural stability and CO 2 tolerance, is an important research direction for the successful realization of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, a novel double perovskite mixed ionic conductor, i.e., Sr 2 Fe 1.3 Ga 0.2 Mo 0.5 O 6-δ (SFGM), is developed by Ga-doping at Fe-sites of Sr 2 Fe 1.5 Mo 0.5 O 6-δ (SFM) and evaluated as a cathode material in IT-SOFCs. At 750 °C, the area specific resistance (ASR) of SFGM cathode is found to be 0.099 Ω cm2, which is ~50% lower than SFM cathode (0.224 Ω cm2) in 20% O 2 /N 2 atmosphere. Moreover, SFGM exhibits outstanding CO 2 tolerance due to its excellent CO 2 adsorption resistance compared with SFM. The ASR of SFGM remains stable at ~0.13 Ω cm2 during 100 h of continuous operation in 5% CO 2 -containing air. In addition, a large-sized SFGM cathode (30 cm2) is utilized in anode-supported flat-tube SOFCs to demonstrate the potential of SFGM in practical applications. At 750 °C, the as-prepared SFGM-based single-cell provides a stable power of 12 W for 291 h in 5% CO 2 -containing air. The superior electrochemical performance and outstanding CO 2 tolerance of SFGM are promising features for the rapid development of IT-SOFCs. Image 1 • SFGM are firstly evaluated as the cathode for flat tubular solid oxide fuel cell. • Ga-doping enhanced the oxygen-ion transport capability of SFM-based materials. • A low polarization resistance of 0.099 Ω cm2 at 750 °C for SFGM cathode. • SFGM exhibits outstanding CO 2 tolerance. [ABSTRACT FROM AUTHOR]

As the demand for ethylene grows continuously in industry, conversion of ethane to ethylene has become more and more important; however, it still faces fundamental challenges of low ethane conversion, low ethylene selectivity, overoxidation, and instability of catalysts. Electrooxidative dehydrogenation of ethane (EODHE) in a solid oxide electrolysis cell (SOEC) is an alternative process. Here, a multiphase oxide Ce 0.6 Mn 0.3 Fe 0.1 O 2-δ -NiFe-MnO x has been fabricated by a self-assembly process and utilized as the SOEC anode material for EODHE. The highest ethane conversions reached 52.23% with 94.11% ethylene selectivity at the anode side and CO with 10.9 mL min -1 cm -2 at the cathode side, at 1.8 V at 700 °C. The remarkable electrooxidative performance of CMF-NiFe-MnO x is ascribed to the NiFe alloy and MnO x nanoparticles and improvement of the concentration of oxygen vacancies within the fluorite substrate, generating dual active sites for C 2 H 6 adsorption, dehydrogenation, and selective transformation of hydrogen without overoxidizing the ethylene generated. Such a tailored strategy achieves no significant degradation observed after 120 h of operation and constitutes a promising basis for EODHE.

Intermediate temperature solid oxide fuel cells (IT-SOFCs) have been extensively studied due to high efficiency, cleanliness, and fuel flexibility. To develop highly active and stable IT-SOFCs for the practical application, preparing an efficient cathode is necessary to address the challenges such as poor catalytic activity and CO 2 poisoning. Herein, an efficient optimized strategy for designing a high-performance cathode is demonstrated. By motivating the phase transformation of BaFeO 3-δ perovskites, achieved by doping Pr at the B site, remarkably enhanced electrochemical activity and CO 2 resistance are thus achieved. The appropriate content of Pr substitution at Fe sites increases the oxygen vacancy concentration of the material, promotes the reaction on the oxygen electrode, and shows excellent electrochemical performance and efficient catalytic activity. The improved reaction kinetics of the BaFe 0.95 Pr 0.05 O 3-δ (BFP05) cathode is also reflected by a lower electrochemical impedance value (0.061 Ω·cm 2 at 750 °C) and activation energy, which is attributed to high surface oxygen exchange and chemical bulk diffusion. The single cells with the BFP05 cathode achieve a peak power density of 798.7 mW·cm -2 at 750 °C and a stability over 50 h with no observed performance degradation in CO 2 -containing gas. In conclusion, these results represent a promising optimized strategy in developing electrode materials of IT-SOFCs.

Mixed oxygen ionic and electronic conduction is a vital function for cathode materials of solid oxide fuel cells (SOFCs), ensuring high efficiency and low-temperature operation. However, Fe-based layered double perovskites, as a classical family of mixed oxygen ionic and electronic conducting (MIEC) oxides, are generally inactive toward the oxygen reduction reaction due to their intrinsic low electronic and oxygen-ion conductivity. Herein, Zn doping is presented as a novel pathway to improve the electrochemical performance of Fe-based layered double perovskite oxides in SOFC applications. The results demonstrate that the incorporation of Zn ions at Fe sites of the PrBaFe 2 O 5+δ (PBF) lattice simultaneously regulates the concentration of holes and oxygen vacancies. Consequently, the oxygen surface exchange coefficient and oxygen-ion bulk diffusion coefficient of Zn-doped PBF are significantly tuned. The enhanced mixed oxygen ionic and electronic conduction is further confirmed by a lower polarization resistance of 0.0615 and 0.231 Ω·cm 2 for PrBaFe 1.9 Zn 0.1 O 5+δ (PBFZ0.1) and PBF, respectively, which is measured using symmetric cells at 750 °C. Moreover, the PBFZ0.1-based single cell demonstrates the highest output performance among the reported Fe-based layered double perovskite cathodes, rendering a peak power density of 1.06 W·cm -2 at 750 °C and outstanding stability over 240 h at 700 °C. The current work provides a highly effective strategy for designing cathode materials for next-generation SOFCs.

Perovskite oxide Sr2Fe1.3Cu0.2Mo0.5O6-δ (SFCM) is prepared and evaluated as a novel cathode material for solid oxide electrolytic cells (SOECs). At 750 °C, the interfacial polarization resistance value decreased from 1.834 to 1.125 Ω cm2 and the SFCM cathode exhibited excellent stability for 100 h, without any significant attenuation, at an electrolytic voltage of 1.5 V.