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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]

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]

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]

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]

[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]

[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]

• Cu-doped (La 0.2 Sr 0.8) 0.95 Ti 0.65- x Mn 0.35 Cu x O 3- δ(LSTMC)are firstly evaluated as SOEC cathode. • LSTMC greatly enhances the catalytic activity by enhancing the chemisorption of CO 2. • The catalytic reaction mechanisms of LSTMC are discussed. • A max electrolytic current density of 2.33 A cm−2 is obtained under 1.8 V at 800 °C. Solid oxide electrolysis cell (SOEC) is a promising technology to efficiently convert carbon dioxide. However, the lack of suitable cathode, with desirable catalytic activity, limits the advancement of SOEC. Herein, we report a novel (La 0.2 Sr 0.8) 0.95 Ti 0.65- x Mn 0.35 Cu x O 3-δ (LSTMC x , x = 0, 0.05, 0.1 and 0.15) as a high-performance cathode, co-doped with hetero-valent Cu and Mn ions at B-site synergistically regulates the surface environment of LST. Cu doping significantly improved the catalytic activity by enhancing the chemisorption of CO 2 , and Mn doping increased the concentration of oxygen vacancies, resulting in abundant electrochemically active sites. Moreover, the as-prepared LSTMC render a higher electrocatalysis performance (2.33 A cm−2 at 1.8 V and 800 °C) than the previously reported perovskite-based cathodes. In addition, the LSTMC-based single cell did not exhibit any significant performance degradation after long-term stability test (100 h) under pure CO 2. Therefore, this newly developed perovskite is considered as a promising cathode for SOEC. [ABSTRACT FROM AUTHOR]