CO 2 electrolysis via solid oxide electrolysis cell (SOEC) has shown promising practical applications in CO 2 conversion and renewable electricity storage due to low overpotential, large current density, high Faradaic efficiency, and energy efficiency facilitated by high-temperature operation. [1] Perovskites have been extensively investigated as cathode materials for direct CO 2 electrolysis in SOEC in the absence of protective gas [2] ; however, the perovskites still suffer from insufficient CO 2 electrolysis performance. [3] In situ exsolving metal nanoparticles on the perovskite surface have been explored as an efficient strategy to improve CO 2 electrolysis performance due to the exsolution of highly active metal nanoparticles and the simultaneous generation of oxygen vacancies within perovskite, where abundant metal-oxide interfaces are generated for highly efficient CO 2 electrolysis. [4] In addition, reversible exsolution and dissolution of metal nanoparticles in perovskite have been proposed as vital properties for resolving the possible particle agglomeration and coke formation during a long-term operation of SOECs. [2b,5] To date, although some perovskites have demonstrated redox reversibility with exsolution and dissolution of metal nanoparticles in reducing and oxidizing atmosphere, [6] fundamental understanding of these phenomena is still scarce. [7] Ex situ scanning/transmission electron microscopy (SEM/ TEM) and X-ray diffraction (XRD) techniques have been employed to investigate the morphology and crystalline evolution after reducing and oxidizing treatments. [8] Irvine et al. found that a decrease in the stoichiometry of perovskite from A/B = 1 to A/B<1 could break the bottleneck of exsolution level and facilitate high-population exsolution of metal nanoparticles. [7,9] Kim et al. investigated the reducibility of different cations in perovskite using co-segregation energy as a descriptor. The co-segregation energy of B-site dopant and oxygen vacancies plays a critical role in the exsolution. [10] Furthermore, Luo et al. used in situ TEM to investigate the exsolution of Co nano particles in Pr 0.5 Ba 0.5 Mn 0.9 Co 0.1 O x (PBMCo) perovskite, excluding the possibility of metal nanoparticles Reversible exsolution and dissolution of metal nanoparticles in perovskite has been investigated as an efficient strategy to improve CO 2 electrolysis performance. However, fundamental understanding with regard to the reversible exsolution and dissolution of metal nanoparticles in perovskite is still scarce. Herein, in situ exsolution and dissolution of CoFe alloy nanoparticles in Co-doped Sr 2 Fe 1.5 Mo 0.5 O 6-δ (SFMC) revealed by in situ X-ray diffraction, scanning transmission electron microscopy, environmental scanning electron microscopy, and density functional theory calculations are reported. Under a reducing atmosphere, facile exsolution of Co promotes reduction of the Fe cation to generate CoFe alloy nanoparticles in SFMC, accompanied by structure transformation from double perovskite to layer...

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In situ exsolved FeNi3 nanoparticles on nickel doped Sr2Fe1.5Mo0.5O6−δ perovskite greatly enhance the performance of the electrochemical CO2 reduction reaction.

Metal nanoparticles anchored on perovskite through in situ exsolution under reducing atmosphere provide catalytically active metal/oxide interfaces for CO2 electrolysis in solid oxide electrolysis cell. However, there are critical challenges to obtain abundant metal/oxide interfaces due to the sluggish diffusion process of dopant cations inside the bulk perovskite. Herein, we propose a strategy to promote exsolution of RuFe alloy nanoparticles on Sr2Fe1.4Ru0.1Mo0.5O6−δ perovskite by enriching the active Ru underneath the perovskite surface via repeated redox manipulations. In situ scanning transmission electron microscopy demonstrates the dynamic structure evolution of Sr2Fe1.4Ru0.1Mo0.5O6−δ perovskite under reducing and oxidizing atmosphere, as well as the facilitated CO2 adsorption at RuFe@Sr2Fe1.4Ru0.1Mo0.5O6−δ interfaces. Solid oxide electrolysis cell with RuFe@Sr2Fe1.4Ru0.1Mo0.5O6−δ interfaces shows over 74.6% enhancement in current density of CO2 electrolysis compared to that with Sr2Fe1.4Ru0.1Mo0.5O6−δ counterpart as well as impressive stability for 1000 h at 1.2 V and 800 °C.

In situ exsolution of metal nanoparticles in perovskite under reducing atmosphere is employed to generate a highly active metal–oxide interface for CO2 electrolysis in a solid oxide electrolysis cell. Atomic‐scale insight is provided into the exsolution of CoFe alloy nanoparticles in La0.4Sr0.6Co0.2Fe0.7Mo0.1O3−δ (LSCFM) by in situ scanning transmission electron microscopy (STEM) with energy‐dispersive X‐ray spectroscopy and DFT calculations. The doped Mo atoms occupy B sites of LSCFM, which increases the segregation energy of Co and Fe ions at B sites and improves the structural stability of LSCFM under a reducing atmosphere. In situ STEM measurements visualized sequential exsolution of Co and Fe ions, formation of CoFe alloy nanoparticles, and reversible exsolution and dissolution of CoFe alloy nanoparticles in LSCFM. The metal–oxide interface improves CO2 adsorption and activation, showing a higher CO2 electrolysis performance than the LSCFM counterparts.

Electrolysis voltage efficiently diminishes the oxidation of an Ni/YSZ cathode during pure CO2 electrolysis in a solid oxide electrolysis cell.

Oxidative dehydrogenation of ethane (ODE) is limited by the facile deep oxidation and potential safety hazards. Now, electrochemical ODE reaction is incorporated into the anode of a solid oxide electrolysis cell, utilizing the oxygen species generated at anode to catalytically convert ethane. By infiltrating γ‐Al2O3 onto the surface of La0.6Sr0.4Co0.2Fe0.8O3‐δ‐Sm0.2Ce0.8O2‐δ (LSCF‐SDC) anode, the ethylene selectivity reaches as high as 92.5 %, while the highest ethane conversion is up to 29.1 % at 600 °C with optimized current and ethane flow rate. Density functional theory calculations and in situ X‐ray photoelectron spectroscopy characterizations reveal that the Al2O3/LSCF interfaces effectively reduce the amount of adsorbed oxygen species, leading to improved ethylene selectivity and stability, and that the formation of Al‐O‐Fe alters the electronic structure of interfacial Fe center with increased density of state around Fermi level and downshift of the empty band, which enhances ethane adsorption and conversion.

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