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In the dry reforming of methane (DRM), the oxygen vacancies on the surface of Ni/CeO 2 catalyst play an important role in CO 2 activation, catalytic performance and coke resistance. Herein, Ni/CeO 2 catalysts doped with different amounts of La were investigated to reveal the relationship between oxygen vacancies and catalytic behavior. The addition of La leads to the reduction in size of Ni particles and stronger metal-support interaction (SMSI). Furthermore, the highest proportion of oxygen vacancies is found in 10 wt% La doped Ni/CeO 2 catalyst, which is beneficial for CO 2 activation and CH 4 dissociation. The Ni/CeLa10 catalyst shows stable methane conversion during 100 h of stability test, which is maintained at 80% without obvious decrease at 750 °C. Therefore, the catalysts with more oxygen species display outstanding activity for the DRM and assisted ability in carbon resistance. This work aims to provide a molecular understanding of the modification of DRM's inherent surface sites. • A suitable amount of La addition is crucial for the modification of CeO 2 support. • Both the oxygen vacancy and basic support are responsible for CO 2 activation. • The highly Ni dispersion and moderate SMSI decrease CH 4 activation energy over Ni/CeLa10. • The Ni/CeLa10 catalyst shows the lowest carbon deposition during the 100 h of stability test. [ABSTRACT FROM AUTHOR]

Proton conducting solid oxide fuel cells (H–SOFCs) with BaZr 0·1 Ce 0·7 Y 0·2 O 3-δ as electrolyte were fabricated to couple the removal of nitrogen oxides in power generation technology. Specially, a deliberately designed cathode with the composition of La 0·3 Sr 0·7 Mn 0·8 Mg 0·2 O 3−δ was prepared to realize this dual function. The results indicated that the incorporation of Mg ions in La 0·3 Sr 0·7 MnO 3−δ can improve its ability to adsorb NO and the cathode activity. At 800 °C, when using the NO as oxidant, single cell with La 0·3 Sr 0·7 Mn 0·8 Mg 0·2 O 3−δ cathode was able to obtain peak power density of 48 mW cm−2 and achieve the conversion of NO to N 2 more than 48%. These findings suggested that power generation coupling deNO via H–SOFC is possible and La 0·3 Sr 0·7 Mn 0·8 Mg 0·2 O 3−δ was a promising cathode for this application. [ABSTRACT FROM AUTHOR]

In this account, we report a facile and environmentally friendly method for preparing surface dealloyed nanocomposite (SD-PtCo/CNT) as an active electrocatalyst towards the ethanol oxidation, and as a low-cost technique for the fabrication of direct bioethanol fuel cell using biomass-derived ethanol. The scanning transmission electron microscopy (STEM) images confirmed the dealloyed nanostructure surface of the as-prepared catalysts. The electrochemical tests indicated that the SD-PtCo/CNT nanocomposites had higher electrocatalytic activities and excellent durabilities toward the ethanol electrooxidation. The enhanced performance resulted from the superior distribution of the bimetallic PtCo catalyst nanoparticles and the dealloyed surface structure. Moreover, the anion membrane-based direct bioethanol fuel cells assembled from this nanocomposites as anodes demonstrated a superior output performance of 88.6 mW cm −2 . This value was enhanced to 3.2-folds of that acquired on the commercial Pt/C. These findings suggested that the fabricated direct bioethanol fuel cells had substantial performance and low cost, and thus could be potential for future applications. [ABSTRACT FROM AUTHOR]

Ni modified Ce 0.6 Mn 0.3 Fe 0.1 O 2 (Ni-CMF) material is evaluated as an anode material for hybrid direct carbon fuel cell (HDCFC). The Temperature Programmed Reaction (TPR) and GC test results show that the Ni additive significantly promotes the oxidation of carbon and consequently accelerates the formation rate of CO. Moreover, the Ni-CMF material is found to show a high electrical conductivity compared to pure CMF in HDCFC operating conditions. Taking advantage of the excellent catalytic activity and high conductivity, the electrolyte-supported HDCFC with Ni-CMF anode shows a high maximum power density of 580.7 mW cm −2 at 800 °C, when activated carbon is used as the fuel. Furthermore, the cell displays good stability under galvanostatic operation at current density of 50 mA cm −2 at 750 °C. These results indicate that the designed Ni-CMF composite material has the potential to be developed as an alternative anode for HDCFCs. [ABSTRACT FROM AUTHOR]

The performance and stability of direct carbon solid oxide fuel cells (DCSOFCs) are severely affected by the electrocatalytic activity of their anode materials. In this work, a cobalt doped layered perovskite, (PrBa) 0.95 Fe 1.8−x Co x Nb 0.2 O 5+δ (PBFCo x N, x = 0, 0.1, 0.2, 0.3), is investigated as the anode material for a DCSOFC. Co 3 Fe 7 alloy particles are exsolved on the perovskite substrate under the reduction of carbon, which improves CO chemisorption and electrochemical oxidation. This enhances the electrochemical performance of the anode. The electrolyte-supported cell with a (PrBa) 0.95 Fe 1.6 Co 0.2 Nb 0.2 O 5+δ (PBFCo 0.2 N) anode achieves a peak power density of 525.6 mW cm−2 at 800 °C, fueled by activated carbon. The performance of this anode material is comparable to or exceeds that of previously reported anodes, indicating that the PBFCo 0.2 N anode is a promising option for DCSOFCs. • Co 3 Fe 7 nanoparticles can exsolve on the anode in a carbon fuel atmosphere. • Low-valence Co2+ dopant improve the conductivity. • The doping of Co ions can effectively improve the chemical adsorption activity of CO. • High power densities are achieved at 800 ℃ in carbon fuel. [ABSTRACT FROM AUTHOR]

In this paper, the partial substitution of atomic elements from the A site of a perovskite is investigated in order to develop cathode materials for solid oxide fuel cell (SOFC) applications. Herein, Sr 2−x Ca x Fe 1.5 Mo 0.5 O 6−δ (SCFM), compounds were investigated by characterizing structural properties, chemical compatibility, electrical properties, electrochemical performance and stability. Thermal expansion coefficients were found to decrease when increasing the Ca content. X-ray photoelectron spectroscopy analysis suggests that Ca doping significantly affects the Fe 2+ /Fe 3+ and Mo 6+ /Mo 5+ ratios. For a doping level of x = 0.4, the sample showed the lowest interface polarization ( R p ), the highest conductivity and a maximum power density of 1.26 W cm −2 at 800 °C. These results suggest that SCFM cathode materials are excellent candidates for intermediate temperature solid oxide fuel cells applications. [ABSTRACT FROM AUTHOR]

Engineering of A-site deficiency in perovskites can be critical for designing new materials with required functional properties. In this article, A-site deficient Sr 2-x Fe 1.4 Ni 0.1 Mo 0.5 O 6-δ (x = 0-0.1, Sr 2-x FNM) perovskites have been synthesized and characterized as anode materials for solid oxide fuel cells. X-ray photoelectron spectroscopy data indicate that Sr deficiency changes valence states of B-site cations. The introduction of A-site deficiency has shown to improve the chemical stability of the as-prepared materials under reducing conditions. With increasing of Sr deficiency, the conductivity in 5% H 2 /Ar increases markedly, reaching a peak value of 26.6 S cm −1 at x = 0.05. While further increasing of x reduces the conductivity by affecting the mobility of electronic charge carriers. The La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3 electrolyte-supported cell with La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3 cathode and Sr 1.95 Fe 1.4 Ni 0.1 Mo 0.5 O 6-δ anode demonstrates a maximum power density of 606 mW cm −2 at 800 °C operating in H 2 . Such designed A-site deficiency perovskite has the potential to be applied as SOFC anode materials. [ABSTRACT FROM AUTHOR]

The porous Mn 2 Co 1 O x catalysts are prepared by a one-step combustion (CB) method for low temperature deNO x process. This catalyst displays an excellent NH 3 -SCR activity, achieving 100% NO x conversion at 150–300 °C. In addition, the catalyst shows high N 2 selectivity, wide operating temperature window, high stability, and high H 2 O and SO 2 resistance. The crystalline phase of CoMn 2 O 4 , porous structure and large specific surface areaare beneficial for the deNO x activity. The catalyst exists abundant Mn 4 + , Co 3 + and surface adsorbed oxygen species, which improve the catalyst's redox ability. Plenty of acid sites from the strong interaction of manganese and cobalt oxide enhance the catalyst performance. [ABSTRACT FROM AUTHOR]

Nanoscale oxide Ce 0.5 Zr 0.5 O 2 powder has been prepared by a microwave combustion method as the anode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The Ce 0.5 Zr 0.5 O 2 material has been characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and the BET method. The NiO–Ce 0.5 Zr 0.5 O 2 anode-supported cells are prepared by phase inversion technique and YSZ electrolyte thin film is obtained by dip-coating. The dual-pore structure anode and dense electrolyte are observed by SEM after co-firing process. Excellent electrochemical performance of single cell is demonstrated operating on hydrogen (3% H 2 O), exhibiting the maximum power densities of 218, 342 and 508 mW cm −2 at 700, 750 and 800 °C, respectively. In addition, NiO–Ce 0.5 Zr 0.5 O 2 anode possess high resistance to carbon deposition, indicating which could be promising candidate anodes for direct hydrocarbon SOFCs. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, Ni/YSZ and Ni–CeO2/YSZ anodes for a solid oxide fuel cell (SOFC) were prepared by tape casting and vacuum impregnation. By this method, the Ni content in the anode could be reduced compared to the traditional tape casting method. It was found that adding CeO2 into the Ni/YSZ anode by a Ni(NO3)2 and Ce(NO3)3 mixed impregnation could further enhance cell performance. This was investigated in H2 at 1073K. XRD patterns indicated that CeO2 and Ni were separate phases, and the CeO2 addition could enhance the Ni dispersion on the YSZ framework surface which was observed by SEM images. It was shown that adding CeO2 into the Ni anodes could decrease the cell polarization resistance. The maximum power density for cells with 25wt.% Ni, 5wt.% CeO2–25wt.% Ni/YSZ, or 10wt.% CeO2–25wt.% Ni/YSZ anode was 230mWcm−2, 420mWcm−2 and 530mWcm−2, respectively, in H2 at 1073K. The OCV for these cells was 1.05–1.09V, indicating that a dense electrolyte film was obtained by co-firing porous YSZ layer and dense YSZ layer. [Copyright &y& Elsevier]

In this study, a multimetallic core–bishell electrocatalyst, Ni@Au@Pd was fabricated. The catalyst consisting of a Ni core and Au@Pd bishell was synthesized using reduced graphene oxide (rGO) as support via chemical reduction-replacement technique. For comparative analysis, the bimetallic core–shell electrocatalyst, Ni@Pd-rGO as a control was also synthesized. A test for electrochemical activity toward oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) was then conducted in an alkaline medium. The results showed that Ni@Au@Pd-rGO exhibited a half-wave potential (0.7713 V) similar to that of Ni@Pd-rGO, which is more positive than that of commercial carbon supported platinum (Pt/C). Furthermore, a higher limited current (5.6 mA cm−2) compared to Pt/C and Ni@Pd-rGO was obtained for ORRs. In OERs, Ni@Au@Pd-rGO exhibited the most negative onset potential (1.5663 V), the lowest overpotential (∼0.52 V), and the lowest Tafel slope (0.199 V decade−1) among these three materials. As a result, Ni@Au@Pd-rGO was confirmed to be an effective bifunctional electrocatalyst for ORRs and OERs. The enhanced activity is attributed to the geometric and electronic effect, the synergistic action of three metals, and the relatively stable Ni@Au@Pd system. All these factors result in an overall good performance as cathode catalyst in lithium-air batteries. • Multimetallic core-bishell Ni@Au@Pd-rGO have a high effiencicy as a bifunctional electrocatalyst in both ORRs and OERs. • High activity bifunctional catalyst for ORRs and OERs was prepared via a facile and easy process. • In ORRs, the half-wave potential of Ni@Au@Pd-rGO is 0.7713 V vs. RHE, and the limited current is 5.6mA/cm2. • In OERs, the onset potential of Ni@Au@Pd-rGO is 1.5663 V vs.RHE, and the Tafel slope is 0.199 V/decade. • Ni@Au@Pd-rGO has a good performance as cathode catalyst in Li–O 2 batteries. [ABSTRACT FROM AUTHOR]

Protonic ceramic electrolysis cells (PCECs) have attracted significant attention as a promising technology for green hydrogen production and conversion. However, traditional PCECs oxygen electrodes exhibit poor electrochemical performance because of their limited hydration ability and lack of intrinsic protonic conductivity. In this study, a W-doped perovskite oxide, Sr 2 Fe 1.5 Mo 0.4 W 0.1 O 6-δ (SFMW), with a strong hydration capacity and an accelerated proton mobility, was designed to serve as the oxygen electrode in PCECs. The results indicate that W doping enhances the concentration of oxygen vacancies in Sr 2 Fe 1.5 Mo 0.5 O 6-δ (SFM) and facilitates the adsorption of H 2 O onto the oxygen electrode, thereby significantly accelerating proton mobility. The bulk diffusion coefficient of protons (D H) in SFMW, estimated through electrical conductivity relaxation measurement, can reach up to 2.86 × 10−5 cm∙s−1 at 750 °C, which is significantly higher than that of SFM (7.96 × 10−6 cm∙s−1). Consequently, SFMW exhibited impressive electrochemical performance, as evidenced by its lower polarization resistance (0.072 Ω⋅cm2, 700 °C in air) and higher current density (945 mA/cm2 with a voltage of 1.3 V at 650 °C) in PCECs. These results suggest that accelerating bulk proton transfer by W doping is highly feasible and holds great potential for the development of oxygen electrodes for high-activity PCECs. [ABSTRACT FROM AUTHOR]

A step-wise current-limiting flash sintering process (SCFS process) was proposed to densify La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM) electrolyte. Well-densified microstructures of LSGM samples were obtained at 690 °C under an electric field of 100 V cm−1. Compared with the current-limiting flash sintering process, the spike in power dissipation was avoided, the shrinkage rate of LSGM samples was moderate, and the microstructures of LSGM samples were uniform. The conductivity of LSGM samples sintered via SCFS process at 0.9 A for 30 min reached 0.072 S cm−1 at 850 °C, and this was approximately the same as the value of conventionally sintered LSGM samples at 1400 °C for 10 h. These results proved that SCFS process achieved easy controllability, and it is expected that SCFS process can be applied in industry. • SCFS process was proposed for LSGM electrolyte densification. • The well-densified and uniform microstructures of LSGM were obtained. • The spike in power dissipation was avoided in SCFS process. • SCFS process is expected to be applied in industry. [ABSTRACT FROM AUTHOR]

LiCoO2 (LCO) has been widely adopted as the electrode for lithium‐ion batteries (LIBs) which provide a solution for settling problems referring to energy and environment. The demand for rapid and controllable synthesis of LCO increases dramatically. In this work, reactive flash sintering (RFS), for the first time, was introduced to synthesize LCO rapidly and controllably based on simple oxide precursors. The as‐prepared LCO, investigated by physicochemical property characterization, showed well‐constructed and high crystallinity and controllable morphologies, in which the grain size varied with the magnitude of the applied limited current value, allowing for grain size modulation. Furthermore, the as‐prepared LCO exhibited excellent performance in cyclic stability and rate capacity by contrast with that synthesized by the conventional solid‐phase sintering method. This is admittedly attributed to better crystallinity and less lithium loss. Therefore, RFS provides a new approach for the manufacture of LCO electrode and has the potential to be applied to other electrode materials for LIBs. [ABSTRACT FROM AUTHOR]

The electrocatalytic conversion of ethane to ethylene is an important industrial process since ethylene is useful for the production of various chemical intermediates and polymers. However, this process often requires high temperatures. Metal-oxide heterogeneous interfaces constructed by in-situ exsolved process under reducing conditions would be favorable for promoting the catalyst activity, selectivity, and stability of ethane conversion to ethylene. Herein, Sr 1.95 Fe 1.4 Co 0.1 Mo 0.5 O 6-δ (abbreviated as SFCoM) was prepared as a novel anode material of solid oxide electrolysis cells (SOECs) for green ethylene production by electrochemical oxidative dehydrogenation of ethane. After reduction, nano CoFe particles were in-situ exsolved on SFCoM oxides to form a nano alloy-oxide heterostructure (CoFe@SFCoM) with large numbers of reactive sites, relevant for improving the conversion rate of ethane and the yield of ethylene. At 800 °C, the single cell based on CoFe@SFCoM anode exhibited a current density of 1.89 A cm−2 at 1.6 V with an ethane conversion rate of 36.4% and corresponding ethylene selectivity of 94.5%. After 50 h of testing, the electrolysis current density(∼0.5 A cm−2) and ethylene yield(∼18.43%) of the single cell did not change significantly, showing good stability. In sum, CoFe@SFCoM looks very promising for future use as a SOECs anode for the electro-catalytic conversion of ethane to ethylene. [ABSTRACT FROM AUTHOR]

Solid oxide electrolysis cell (SOEC) is recognized as an effective means to accomplish sustainable development since it is an efficient electrochemical technology for CO 2 emission reduction. However, the electrocatalytic reduction activity of the cathode for CO 2 restricts the development of SOEC. Herein, an A-site deficient perovskite Sr 1·9 Fe 1·3 Cu 0·2 Mo 0·4 Ti 0·1 O 6-δ (SFCMT) was proposed as cathode material that can in situ exsolve uniform Cu nanoparticles. The exsolution of Cu increases the concentration of oxygen vacancies and provides abundant adsorption sites for CO 2 , resulting in excellent electrochemical catalytic capacity. Cu@SFCMT-based single cells exhibit excellent electrolytic performance under pure CO 2 , with current densities up to 3.21 A cm−2 at 1.8 V and 800 °C and interface polarization resistance (Rp) as low as 0.20 Ω cm2 at 800 °C. Furthermore, the current density changes slightly after the 140 h stability test at 1.2 V. Cu@SFCMT exhibits outstanding electrochemical activity and durability, making it a viable SOEC cathode material. [ABSTRACT FROM AUTHOR]

Solid oxide electrolysis cell (SOEC) provides an effective solution to electrochemically convert CO 2 into valuable products with high efficiency, which is also developed as a promising way for the electricity utilization. However, the poor catalytic activity of the electrode material results in slow cathode kinetics for this technology. In this work, we propose a series of Sr x Ti 0.7 Cu 0.2 Mo 0.1 O 3-δ (S x TCM, x = 1, 0.975, 0.95) perovskite oxides as the cathodes of SOEC. By tuning the defects of the materials, abundant oxygen vacancies are stimulated in the perovskite lattice, which effectively improves the oxygen ion transport capacity and also act as the receptors of CO 2 molecule. Uniformly dispersed Cu nanoparticles on STCM substrate are in-situ generated after reduction treatment, leading to the formation of abundant active sites for CO 2 reduction reaction (CO 2 RR). The results of this work demonstrate a general strategy for developing promising catalysts for efficient CO 2 RR. [ABSTRACT FROM AUTHOR]

As an important renewable energy, hydrogen energy becomes an important part of the future energy system. Proton ceramic electrolysis cell (PCEC) enables the efficient, clean, large-scale preparation of hydrogen, which is a new type of energy conversion device, attracting the attention of many researchers. Sr 2 Fe 1.4 Zn 0.1 Mo 0.5 O 6-δ (SFZM) anode materials were developed to investigate the effect of B-site doping of Zn on the electrochemical properties of the Sr 2 Fe 1.5 Mo 0.5 O 6-δ (SFM) materials. The results reveal that the doping of Zn increases the concentration of oxygen vacancies and improves the electrocatalytic activity, which in turn improves the performance of the material. A current density of 408 mA cm−2 has been achieved at 1.3 V when the SFZM-based single cell was operated in an electrolysis mode (50% H 2 O in air) at 600 °C, higher than SFM-based single cells (286 mA cm−2 at 1.3 V). In addition, the SFZM-based single cell exhibited good durability in a stability test at an electrolysis current density of 408 mA cm−2. This work confirms that SFZM is a promising material for proton ceramic electrolysis cell anode. [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]

A high-performance electrocatalyst for oxygen reduction reactions has been developed, which possesses three-dimensional local lattice strain. This localized lattice microstrain reduces the metal–oxygen bond energy, leading to the multi-site optimization of oxygen adsorption and migration, resulting in dual enhancements in catalytic activity and CO 2 resistance. This provides an innovative strategy for the design of high-performance and durable electrochemical catalysts. [Display omitted] • A localized lattice strain (≈1.5%) electrocatalyst has been developed. • The localized microstrain optimizes the process of oxygen adsorption and migration. • This electrode material resulted in a 57.9% reduction in polarization impedance. • Possessing robust resistance to CO 2 poisoning and improved chemical stability. The cathode of a solid oxide fuel cell (SOFC) must exhibit both high activity and robust durability for effective utilization in electrochemical oxygen reduction reaction (ORR). To address this challenge, we present a novel strain engineering strategy that involves the creation of nanoscale local lattice strain microdomains to further enhance the ORR kinetics. Specifically, Ga cations are introduced into some of the B-sites of the perovskite Pr 0.4 Sr 0.6 Fe 0.5 Co 0.5 O 3-δ (PSFC). Benefiting from local lattice strain engineering, the bulk oxygen migration coefficient of the locally strained PSFC sample is significantly enhanced, reaching twice that of the pure PSFC sample at 650 °C. Moreover, the polarization impedance of PSFC (0.102 Ω·cm2) is more than twice that of Pr 0.4 Sr 0.6 Fe 0.4 Co 0.5 Ga 0.1 O 3-δ (PSFCG, 0.043 Ω·cm2) at 800 °C. Microscopic structural analyses and computational calculations indicate that the optimized electronic structure of the rich micro-strain catalyst reduces the bond energy of adjacent B-O bonds and the oxygen transport barrier. This work demonstrates a practical local lattice micro-strain engineering strategy and provides a new approach for improving the performance of ORR electrocatalysts. [ABSTRACT FROM AUTHOR]

Abstract: Continuously graded anode functional layers (CG-AFLs) were fabricated on the Ni–YSZ anode substrates by electrophoretic co-deposition (EPD) technique. The microstructure and composition of the CG-AFLs were investigated. The result showed that uniform and graded structure in AFL was obtained. The single cells were constructed on the basis of CG-AFLs, with a maximum output power density greater than 1.10Wcm−2 obtained at 800°C for the cell with 9.8μm-thick CG-AFL. Electrochemical impedance spectroscopy (EIS) indicated that the excellent cell performance was contributed to the enlargement of triple phase boundary (TPB) by adding the CG-AFL. [Copyright &y& Elsevier]

Tubular Solid Oxide Fuel Cells (TSOFCs) owns plenty of merits not only these of common SOFCs but also some merits including rapid start-up, less sealing requirements which stimulate more and more attempts at the commercialization. This review presents the current status of TSOFCs technology including materials, manufacturing, cell design and system integration. Particularly the route of cell design and diversified applications in the last decades are mainly discussed with the purpose of providing a broad overview of this technology for the new to this field. Moreover, a mini summery displays several power generation devices based on TSOFCs manufactured and demonstrated by research institutes and companies around the world. Image 1 • Recent progress of tubular solid oxide fuel cells is reviewed. • The system integration is emphatically introduced. • First time the current commercialization is traced and summarized. • Urgent problems for the development of tubular solid oxide fuel cells. [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]

Abstract FeF 2 -reduced graphene oxide nanocomposite is in-situ synthesized and assembled into electrode with poly (acrylic acid) binder as a novel sodium ion cathode, which exhibits greatly improved electrochemical performance. The mechanism for the improved performance of the electrode is studied by ex-situ morphology and phase analysis, before and after cycling. The results show that poly (acrylic acid) binder with high adhesion ability can stabilize the electrode structure, thus increase the utilization of active materials. The in-situ hybridization of FeF 2 nanoparticles with reduced graphene oxide can confine the sizes of particles, and restrain the particles agglomeration. As a result, the electrode can attain high capacity and stability. The electrode exhibits superior electrochemical performance: high capacity of 175 mAh g−1 at 0.2 A g−1, high rate capability of 78 mAh g−1 at 10 A g−1, and good cycling stability. The results demonstrate the electrochemical performance of metal fluoride electrode can be enhanced by using highly adhesive materials as binders and the nanostructure construction. Graphical abstract Image 1 Highlights • A novel electrode is prepared using FeF 2 -rGO nanocomposite and PAA binder. • The electrode shows improved capacity, rate capability and cyclic performance. • The improved performance is studied by ex-situ morphology and phase analysis. • PAA binder can increase the utilization of active materials. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ir@NHCSs with hollow and hierarchical porous structure were fabricated through a facile template method. • Ir@NHCSs exhibit excellent bifunctional activity toward ORR and OER in both alkaline aqueous and non-aqueous system. • Li-O 2 batteries with Ir@NHCSs as cathode catalyst show enhanced electrochemical performance. • The stability of the recharged air-cathode architecture was confirmed via SEM. Abstract One of the biggest challenges on the way to the commercialization of lithium-oxygen (Li-O 2) batteries (LOBs) is the exploration of an air electrode with high electronic conductivity, steadily porous architecture, and high-efficiency bifunctional catalytic activity. In this study, nitrogen-doped and iridium decorated carbon spheres with hollow and hierarchical porous structure were successfully fabricated and used as excellent bifunctional electrocatalysts in alkaline aqueous environment as well as in non-aqueous LOBs. This material structure with large pore volume and high specific surface area provides sufficient room and numerous active sites for the deposition of Li 2 O 2 product. Moreover, the in-situ nitrogen doping further enhances the electron conductivity as well as the electrocatalytic activity toward oxygen, yielding a gratifying discharge platform potential of 2.77 V, and a high discharge capacity (6849 mAh g−1). After anchoring with Ir nanoparticles, the resulting composite material presented significantly reduced charge overpotential (0.83 V) and improved reversibility. Meanwhile, owing to the synergistic effect among the porous carbon, nitrogen heteroatom, and Ir nanocrystals, the increased discharge capacity of 8239 mAh g−1 and high discharge plateau of 2.80 V were also achieved. Besides, the excellent stability of the recharged air-cathode architecture was confirmed via ex-situ scanning electron microscopy. [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]

B-site substituted Sr 2 Fe 1.4 X 0.1 Mo 0.5 O 6-δ (SFXM, X = Bi, Al and Mg) are evaluated as anode materials for hybrid direct carbon fuel cells (HDCFCs). The structure, morphology, conductivity and catalytic activity of the as-prepared SFXM anode are systematically investigated. Under a reducing atmosphere, the exsolution of metallic Fe from the SFXM perovskite lattice are demonstrated by the XRD, SEM and TEM observations. Further element valence analysis on reduced SFXM suggests the X doping significantly alters the Fe 3+ /Fe 2+ and Mo 6+ /Mo 5+ ratio, and thus beneficial to the intrinsic conductivity of SFXM. All these advantages are responsible for the good electrochemical performances of SFXM anodes. Meanwhile, among these SFXM anodes, the conductivity, catalytic activity and electrochemical performance all obey the order of SFBM > SFAM > SFMM. The maximum power densities of the La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3 electrolyte supported single cell with SFBM as the anode reaches 399, 287 and 141 mW cm −2 at 800 °C, 750 °C and 700 °C, respectively. Such designed B-site substitution perovskites have great potential to be applied as HDCFC anode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • BaCo 0.4 Fe 0.4 Nb 0.1 Sc 0.1 O 3-δ (BCFNS) oxide is reported as PCEC oxygen electrode. • The synergistic effect of Nb5+ and Sc3+ in tuning hydration has been revealed. • Remarkable electrolytic performance has been demonstrated in BCFNS-based PCEC. Proton ceramic electrolytic cells (PCECs) are regarded as superior candidates for largescale hydrogen production by water electrolytic because they are efficient and weakly temperature-dependent. However, the intrinsically poor water-storage capability (hydration) and slow proton mobility of traditional PCEC oxygen electrodes retards the activity of electrochemical water decomposition to oxygen. The sluggish decomposition process has prevented the extensive application of PCECs. Herein, we report a Nb5+ and Sc3+ co-doped BaCo 0.4 Fe 0.4 Nb 0.1 Sc 0.1 O 3-δ (BCFNS) perovskite oxygen electrode that exhibits remarkably low polarization resistances (e.g., 0.079 Ω·cm2 at 650 °C) in air humidified with 3 vol% H 2 O. Both experiments and computational calculations linked this high performance to the synergistic effect of Nb5+ and Sc3+ in tuning the oxygen-vacancy concentration and the hydration reaction between oxygen vacancies and water molecules. This unique synergistic mechanism endows BCFNS with strong hydration capacity, boosting the formation of protonic defects and reducing the proton-migration barrier. Benefiting from these features, a single PCEC with a BCFNS oxygen electrode achieved much higher current densities than newly reported PCECs: 1224.91, 914.05, 622.18, and 314.89 mAcm−2 at 1.3 V and 650 °C, 600 °C, 550 °C, and 500 °C, respectively. Such excellent electrolytic performance suggests that Nb5+ and Sc3+ co-doping can promote the hydration capability and proton mobility of electrode materials for high-performance PCECs. [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]

In this work we show that the performance of a Sr 2 Fe 1.5 Mo 0.5 O 6 cathode can be improved by scandium substitutional doping. Herein Sr 2 Fe 1.5-x Sc x Mo 0.5 O 6 (SFSc x M) compounds are synthesized with a doping value (x) varying from 0 to 0.2, using a glycine-nitrate combustion progress. The phase structure and morphology are characterized by X-ray powder diffraction and scanning electron microscopy showing a perovskite structure and a porous microstructure when doping between 0 and 0.1. X-ray photoelectron spectroscopy results indicate that the Sc-doping has a clear effect on Fe 2+ /Fe 3+ and Mo 6+ /Mo 5+ ratios. On cells consisting of SFSc x M electrodes and La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3 electrolytes, Sc doping is found to be very effective in reducing the interfacial polarization resistance. Impedance data analysis of SFSc 0.05 M cathode at a variety of oxygen partial pressures indicates that the rate limiting steps are the dissociation of adsorbed molecular oxygen for the high-frequency arc and the migration of oxygen ions to the triple phase boundary for the low-frequency arc, respectively. The highest single cell peak power density is obtained with the SFSc 0.05 M cathode reaching 1.23 W cm −2 at 800 °C. The results suggest that Sc-doping of SFSc x M can substantially improve the electrochemical performance. [ABSTRACT FROM AUTHOR]

Three-dimensional ordered mesoporous (3DOM) CuCo 2 O 4 materials have been synthesized via a hard template and used as bifunctional electrocatalysts for rechargeable Li-O 2 batteries. The characterization of the catalyst by X-ray diffractometry and transmission electron microscopy confirms the formation of a single-phase, 3-dimensional, ordered mesoporous CuCo 2 O 4 structure. The as-prepared CuCo 2 O 4 nanoparticles possess a high specific surface area of 97.1 m 2 g − 1 and a spinel crystalline structure. Cyclic voltammetry demonstrates that mesoporous CuCo 2 O 4 catalyst enhances the kinetics for either oxygen reduction reaction (ORR) or oxygen evolution reaction (OER). The Li-O 2 battery utilizing 3DOM CuCo 2 O 4 shows a higher specific capacity of 7456 mAh g − 1 than that with pure Ketjen black (KB). Moreover, the CuCo 2 O 4 -based electrode enables much enhanced cyclability with a 610 mV smaller discharge–recharge voltage gap than that of the carbon-only cathode at a current rate of 100 mA g − 1 . Such excellent catalytic performance of CuCo 2 O 4 could be associated with its larger surface area and 3D ordered mesoporous structure. The excellent electrochemical performances coupled with its facile and cost-effective way will render the 3D mesoporous CuCo 2 O 4 nanostructures as attractive electrode materials for promising application in Li-O 2 batteries. [ABSTRACT FROM AUTHOR]

La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM), a promising electrolyte material for intermediate temperature solid oxide fuel cells, can be sintered to a fully dense state by a flash-sintering technique. In this work, LSGM is sintered by the current-limiting flash-sintering process at 690 °C under an electric field of 100 V cm −1 , in comparison with up to 1400 °C or even higher temperature in conventional furnace sintering. The resultant LSGM samples are investigated by scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The SEM images exhibit well-densified microstructures while XRD results show that the perovskite structure after flash-sintering does not changed. EIS results show that the conductivity of LSGM sintered by the current-limiting flash-sintering process increases with sintering current density value. The conductivity of samples sintered at 120 mA mm −2 reaches 0.049 σ cm −1 at 800 °C, which is approximate to the value of conventional sintered LSGM samples at 1400 °C. Additionally, the flash-sintering process is interpreted by Joule heating theory. Therefore, the current-limiting flash-sintering technique is proved to be an energy-efficient and eligible approach for the densification of LSGM and other materials requiring high sintering temperature. [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]

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]

Three-dimensional ordered mesoporous (3DOM) ZnCo 2 O 4 materials have been synthesized via a hard template and used as bifunctional electrocatalysts for rechargeable Li-O 2 batteries. The as-prepared ZnCo 2 O 4 nanoparticles possess a high specific surface area of 127.2 m 2 g −1 and a spinel crystalline structure. The Li-O 2 battery utilizing 3DOM ZnCo 2 O 4 shows a higher specific capacity of 6024 mAh g −1 than that with pure Ketjen black (KB). Moreover, the ZnCo 2 O 4 -based electrode enables much enhanced cyclability with a smaller discharge-recharge voltage gap than that of the carbon-only cathode. Such excellent catalytic performance of ZnCo 2 O 4 could be associated with its larger surface area and 3D ordered mesoporous structure. [ABSTRACT FROM AUTHOR]

The ability to directly utilize hydrocarbons and other renewable liquid fuels is one of the most important issues affecting the large scale deployment of solid oxide fuel cells (SOFCs). Herein we designed La 0.2 Sr 0.7 TiO 3 –Ni/YSZ functional gradient anode (FGA) supported SOFCs, prepared with a co-tape casting method and sintered using the field assisted sintering technique (FAST). Through SEM observations, it was confirmed that the FGA structure was achieved and well maintained after the FAST process. Distortion and delamination which usually results after conventional sintering was successfully avoided. The La 0.2 Sr 0.7 TiO 3 –Ni/YSZ FGA supported SOFCs showed a maximum power density of 600 mW cm −2 at 750 °C, and was stable for 70 h in CH 4 . No carbon deposition was detected using Raman spectroscopy. These results confirm the potential coke resistance of La 0.2 Sr 0.7 TiO 3 –Ni/YSZ FGA supported SOFCs. [ABSTRACT FROM AUTHOR]

A novel electrical current applied technique known as flash sintering has been applied to rapidly (within 10 min) densify electrolytes including Ce0.8Gd0.2O1.9 ( GDC20), Ce0.9Gd0.1O1.95 ( GDC10), and Ce0.8Sm0.2O1.9 ( SDC20) for application in Solid Oxide Fuel Cells ( SOFCs). The densification temperature for the three electrolytes was 554°C, 635°C, and 667°C, respectively, which is far below conventional sintering temperatures. All specimens after flash sintering maintained the pure fluorite structure and exhibited a well-densified microstructure. To investigate the flash-sintering mechanism, we have applied Joule heating effect with blackbody radiation theory, and found that this theory could reasonably interpret the flash-sintering phenomenon by matching theoretically calculated temperature with the real temperature. More importantly, one of the materials inherent properties, the electronic conductivity, has been found correlated with the onset of flash sintering, which indicates that the electrons and holes are the primary current carriers during the start of flash-sintering process. As a result, potential densification mechanisms have been discussed in terms of spark plasma discharge. [ABSTRACT FROM AUTHOR]

The electrochemical performance of one-dimensional porous La 0.5 Sr 0.5 CoO 2.91 nanotubes as a cathode catalyst for rechargeable nonaqueous lithium-oxygen (Li-O 2 ) batteries is reported here for the first time. In this study, one-dimensional porous La 0.5 Sr 0.5 CoO 2.91 nanotubes were prepared by a simple and efficient electrospinning technique. These materials displayed an initial discharge capacity of 7205 mAh g −1 with a plateau at around 2.66 V at a current density of 100 mA g −1 . It was found that the La 0.5 Sr 0.5 CoO 2.91 nanotubes promoted both oxygen reduction and oxygen evolution reactions in alkaline media and a nonaqueous electrolyte, thereby improving the energy and coulombic efficiency of the Li-O 2 batteries. The cyclability was maintained for 85 cycles without any sharp decay under a limited discharge depth of 1000 mAh g −1 , suggesting that such a bifunctional electrocatalyst is a promising candidate for the oxygen electrode in Li-O 2 batteries. [ABSTRACT FROM AUTHOR]

In order to enhance the electrochemical performance of solid oxide fuel cells (SOFCs), a Gd 0.2 Ce 0.8 O 2−δ (GDC) interlayer was introduced to Ba 0.5 Sr 0.5 Fe 0.91 Al 0.09 O 3−δ (BSFA) cathode. The chemical stability and microstructure of the samples were characterized by X-Ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical performance was tested by impedance spectroscopy. The results show that BSFA cathode is chemically and mechanically stable with the existence of a GDC interlayer. The polarization resistance of BSFA cathode with a GDC interlayer was 0.3009 Ω cm 2 and the maximum power density ( P max ) of an anode supported single cell reached 1321 mW cm −2 at 750 °C. Furthermore, a BSFA-GDC composite cathode was prepared and presented excellent performance with the P max of 1957 mW cm −2 at 750 °C, providing a feasible choice for IT-SOFC cathodes. [ABSTRACT FROM AUTHOR]

Li-rich materials are considered the most promising for Li-ion battery cathodes, as high capacity can be achieved. However, poor cycling stability is a critical drawback that leads to poor capacity retention. Here a strategy is used to synthesize a large-grain lithium-rich layered oxides to overcome this difficulty without sacrificing rate capability. This material is designed with micron scale grain with a width of about 300 nm and length of 1–3 μm. This unique structure has a better ability to overcome stress-induced structural collapse caused by Li-ion insertion/extraction and reduce the dissolution of Mn ions, which enable a reversible and stable capacity. As a result, this cathode material delivered a highest discharge capacity of around 308 mAh g −1 at a current density of 30 mA g −1 with retention of 88.3% (according to the highest discharge capacity) after 100 cycles, 190 mAh g −1 at a current density of 300 mA g −1 and almost no capacity fading after 100 cycles. Therefore, Lithium-rich material of large-grain structure is a promising cathode candidate in Lithium-ion batteries with high capacity and high cycle stability for application. This strategy of large grain may furthermore open the door to synthesize the other complex architectures for various applications. [ABSTRACT FROM AUTHOR]

Protonic ceramic fuel cells (PCFCs) have generated significant interest due to their weak temperature dependence and efficient energy conversion. However, traditional cathode materials show poor electrocatalytic activity at a low operating temperature due to their intrinsically slow proton diffusion, which is a long-standing issue that limits the output performance of PCFCs. Herein, the strategy of fluorinating a perovskite cathode is proposed for promoting proton transfer within the bulk of the cathode. This strategy is demonstrated in a fluorinated BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3−δ (BCFZY) perovskite, which reveals a reduced polarization resistance and enhanced PCFC output performance, superior to those of newly reported PCFCs. Combing the experimental characterization and theoretical calculations, we found that the performance improvement was ascribed to the strong inductive effect of F−, which can increase the polarity the M−O bonding and decrease the O···H interaction, thus boosting the production of protonic defects and increasing the protonic diffusion coefficient. [Display omitted] • Fluorinated BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3−δ (BCFZY) perovskite is firstly synthesized as PCFC cathode. • Fluorination enhances the hydration properties and proton mobility of BCFZY perovskite. • Fluorination inductive effect has been proposed to reveal the origin of improved proton mobility. • Peak power density of 0.782 W cm−2 is obtained at 600 °C for a single PCFC using fluorinated BCFZY as cathode. [ABSTRACT FROM AUTHOR]

A strategy of regulating the basicity of perovskite oxygen ions by cation doping is proposed to design cathode materials with high catalytic activity for solid oxide electrolysis cells (SOECs). Specifically, a series of Sr 2 Fe 1.5- x Zr x Mo 0.5 O 6−δ (SFZ x M) perovskites are developed and characterized for its electrocatalytic activity and oxygen ions basicity to investigate the effect on electrochemical performance. The experimental results show that the single cell prepared with the Sr 2 Fe 1.3 Zr 0.2 Mo 0.5 O 6−δ (SFZ2M) cathode reaches a current density of 1.85 A cm−2 at 1.8 V and 800 °C and exhibits good stability over 120 h under CO 2 atmosphere. Combined with first-principles calculations, it is further confirmed that the introduction of low-electronegativity ions can improve the oxygen ions basicity and also increase the oxygen vacancy concentration of the cathode, thereby realizing the improvement of electrochemical performance. Thus, this strategy provides new insights into designing electrodes for direct CO 2 electrolysis as well as other electrochemical catalysis. [Display omitted] • Zr-doped Sr 2 Fe 1.5 Mo 0.5 O 6-δ (SFZxM) perovskites are firstly evaluated as SOEC cathode. • SFZxM materials greatly enhance the chemisorption of CO 2 by increasing the oxygen vacancies concentration. • The introduction of Zr4+ can improve the oxygen ion basicity of SFZxM cathodes. • The improved electrochemical performance is facilitated by the double regulation of oxygen ion basicity and oxygen vacancies. [ABSTRACT FROM AUTHOR]

• Sr 2 Fe 1.5 Mo 0.4 Y 0.1 O 6-δ (SFMY) perovskite is synthesized as the oxygen electrode of PCECs. • SFMY perovskite shows enhanced hydration capacity and special H+/O2−/e− triple conduction. • High electrolytic activity and good operational stability have been demonstrated in the as-fabricated SFMY-based PCEC. Protonic ceramic electrolysis cells (PCECs) are emerging as potential technology to achieve efficient electrochemical hydrogen production and purification due to their high conversion efficiency and low cost. However, their maturity on a large-scale hydrogen production is notoriously hindered by the poor activity and stability of oxygen electrodes. In this work, a Sr 2 Fe 1.5 Mo 0.4 Y 0.1 O 6-δ (SFMY) oxygen electrode was designed, which shows a stable phase structure, enhanced hydration capacity, and special triple conduction (H+/O2−/e−). Electrical conductivity relaxation measurement demonstrated that SFMY showed faster H 2 O surface exchange process and improved bulk ion mobility. The as-fabricated PCEC using SFMY as the oxygen electrode can achieve a current density as high as 1570, 1235, 827, and 516 mA·cm−2 at 750 °C, 700 °C, 650 °C, and 600 °C, respectively, at a voltage of 1.3 V while displaying excellent operation stability at 700 °C during the test period of about 240 h. These results suggest that SFMY can be a potential oxygen electrode for PCECs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Construction of a composite heterostructure of alkaline-earth metal compounds and Sr 2 Fe 1.5 Mo 0.5 O 6−δ (SFM) double perovskite oxides by alkaline-earth metal infiltration was proposed. • The heterostructure enriches the surface active sites and led to the expansion of the triple-phase boundary. • The infiltration of alkaline-earth metal improves the adsorption and activation process of CO 2. • SFM-MCO 3 cathodes exhibit excellent electrochemical performance and the single cell reached the current density of 1.723 A cm−2 at 1.8 V and 800 °C. Solid oxide electrolysis cell (SOEC) can efficiently convert CO 2 to CO using renewable energy sources, which can alleviate the threatening impact of excessive CO 2 emissions on the human life and environment. Moreover, it also realizes chemical storage of available electricity to ease the energy consumption crisis. Designing cathode materials with abundant active sites and high-efficiency electrochemical catalytic activity toward CO 2 reduction is crucial for realizing practical applications of SOEC. Herein, construction of a composite heterostructure of alkaline-earth metal compounds and Sr 2 Fe 1.5 Mo 0.5 O 6−δ (SFM) double perovskite oxides by alkaline-earth metal infiltration was proposed. This strategy enriched the reactive sites and led to the expansion of the triple-phase boundary, thereby effectively improving the electrochemical performance of SOEC. The experimental results show that the infiltration of alkaline-earth metal led to significant increase in the surface active sites, improvement in the adsorption and activation process of CO 2 , and promotion of the formation of activated carbonate intermediates. The current density on the CaCO 3 -infiltrated SFM cathode reached 1.723 A cm−2, while the current density on the SFM cathode could only reach 1.117 A cm−2 at 1.8 V and 800 °C. The alkaline-earth metal infiltration strategy not only improves the electrochemical performance, but also maintains excellent stability after 100 h of operation at high temperature and 12 redox cycles. All these results indicate that the construction of heterostructure through alkaline-earth metal infiltration provides an effectual strategy for improving the electrochemical performance of SOEC. [ABSTRACT FROM AUTHOR]

In this paper, niobium doping is evaluated as a means of enhancing the electrochemical performance of a Sr 2 Fe 1.5 Mo 0.5 O 6− δ (SFM) perovskite structure cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs) applications. As the radius of Nb approximates that of Mo and exhibits +4/+5 mixed valences, its substitution is expected to improve material performance. A series of Sr 2 Fe 1.5 Mo 0.5− x Nb x O 6− δ ( x = 0.05, 0.10, 0.15, 0.20) cathode materials are prepared and the phase structure, chemical compatibility, microstructure, electrical conductivity, polarization resistance and power generation are systematically characterized. Among the series of samples, Sr 2 Fe 1.5 Mo 0.4 Nb 0.10 O 6− δ (SFMNb 0.10 ) exhibits the highest conductivity value of 30 S cm −1 at 550 °C, and the lowest area specific resistance of 0.068 Ω cm 2 at 800 °C. Furthermore, an anode-supported single cell incorporating a SFMNb 0.10 cathode presents a maximum power density of 1102 mW cm −2 at 800 °C. Furthermore no obvious performance degradation is observed over 15 h at 750 °C with wet H 2 (3% H 2 O) as fuel and ambient air as the oxidant. These results demonstrate that SFMNb shows great promise as a novel cathode material for IT-SOFCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • (PrBa) 0.95 Fe 1.6 Ni 0.2 Nb 0.2 O 5+δ as the cathode material of SOEC is reported first time. • In situ fabrication of highly active nanoalloy catalyst for CO 2 RR. • The abundant oxygen vacancies and active nanoalloy significantly improves the mass transfer process. • Good electrochemical performance and stability induced by efficient cathode reactions. The electroreduction of CO 2 through solid oxide electrolysis cells (SOEC) is considered as a promising technology for mitigating climate changes related to global warming. A SOEC system can effectively reduce polarization losses and best utilize process heat to electrolyze CO 2 to produce CO. However, this technology is hindered by the sluggish cathode kinetics, which is mainly due to the poor catalytic activity for the CO 2 reduction reaction. Herein, this work develops an A-site ordered layered perovskite oxide, (PrBa) 0.95 Fe 1.6 Ni 0.2 Nb 0.2 O 5+δ (PBFNN), as an efficient cathode catalyst for CO 2 -SOEC. FeNi 3 nanoparticles are in situ generated on the surface of perovskite substrate after reduction, the resulting active alloy-perovskite interfaces between FeNi 3 and PBFNN substrate can effectively promote the CO 2 reduction reaction (CO 2 RR). The nanoparticles and abundant oxygen vacancies of FeNi 3 -PBFNN significantly enhance CO 2 adsorption and activation, which is verified by the CO 2 -temperature programmed desorption measurement and density functional theory calculations. Distribution of relaxation time analysis and electrochemical performance characterization indicate that this interface engineering at nanoscale greatly improves the catalytic activity of the cathode for CO 2 RR. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-Sn nanoparticles were formed through in-situ exsolution in the Sr 1.95 Fe 1.4 Sn 0.1 Mo 0.5 O 6-δ perovskite. • The CO 2 adsorption capacity and electrocatalytic activity are significately enhanced by Fe-Sn nanoparticles. • The single cell furnished excellent CO 2 electrolysis performance, and the maximum current density of 3.269 A cm−2 at 1.8 V and 800 °C was achieved. Herein, the Sn-doped perovskite oxide Sr 1.95 Fe 1.4 Sn 0.1 Mo 0.5 O 6-δ (SFSnM), which exhibited in situ exsolved Fe-Sn alloy nanoparticles and controllable phase transformation, was synthesized to catalyze the reduction of CO 2 through A-site deficiency regulation. The in situ exsolved Fe-Sn alloy nanoparticles were uniformly distributed on the surface of the SFSnM substrate after reduction, which significantly enhanced the catalytic activity and CO 2 adsorption capacity of the SFSnM cathode. Moreover, a single cell with an FeSn@SFSnM cathode exhibited excellent CO 2 electrolysis performance, achieving a current density of 3.269 A cm−2 and an R p value of 0.145 Ω cm2 at 800 °C and 1.8 V. Additionally, no significant performance attenuation was observed during a long-term stability test (200 h), indicating the good stability of FeSn@SFSnM cathode. Overall, these results demonstrated that the designed FeSn@SFSnM cathode shows great potential for high-performance solid oxide electrolysis cells (SOECs). [ABSTRACT FROM AUTHOR]

Abstract: BaZr0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb), a promising proton conductor of poor sinterability used in Solid Oxide Fuel Cells (SOFCs), has been densified in one hour at 850 °C by applying direct current sintering technique (DC-sintering). Under a constant electrical field, the current density through the specimen of BZCYYb rises rapidly when the temperature increases to a certain value. In DC-sintering process, we restrict the current density when the sharp increase occurs. By limiting current density to different values for one hour, we find that current density is the most important factor in DC-sintering process. The conductivity and the grain size of BZCYYb electrolyte increase significantly with the enhanced current density, while the different initial applied electrical fields have negligible effect. The stable stage of DC-sintering process can be explained by Joule heating. Corresponding real temperature of specimens is estimated by applying black body radiation theory. [Copyright &y& Elsevier]

Compositionally continuously graded cathode layers (CGCLs) of (Ba0.5Sr0.5)(Fe0.91Al0.09)O3−δ –Gd0.1Ce0.9O2 (BSFA–GDC) have been constructed by a handy and effective technique called wet powder spraying (WPS). CGCLs exhibit similar thermal expansion coefficient (TEC) value between adjacent thin layers. The continuously graded structure and the well-distributed components of BSFA–GDC cathode are confirmed by morphological characterization with scanning electron microscopy (SEM), and by compositional analysis with energy dispersion X-ray spectrometer (EDS), respectively. The polarization resistance (R p) of CGCLs with three different thicknesses is investigated by electrochemical impedance spectra (EIS). The EIS results show that CGCLs with a moderate thickness of 20 μm achieve the lowest R p of 0.301 Ω cm2 at 800 °C. In addition, anode-supported single cells with the configuration of NiO–YSZ/YSZ/GDC/BSFA–GDC have been fabricated and tested. The cell with the CGCLs thickness of 20 μm reaches the highest output power density of 848 mW cm−2 at 800 °C. [ABSTRACT FROM AUTHOR]