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The solid oxide electrolysis cell (SOEC) is generally recognized as the optimal electrochemical conversion device for CO2 reduction reaction due to its high efficiency. However, the development of SOECs is limited by the lack of cathode materials with high electrocatalytic activity and stability. Perovskite cathodes exhibit redox stability at high temperatures, but their electrocatalytic activity remains limited. In this study, both A-site defects and B-site doping are designed for the perovskite La0.5Sr0.5TiO3−δ. This cathode material promotes B-site exsolution through A-site defects, resulting in high-density nanoparticles. The in situ exsolved nanoparticles and the oxide substrate form a metal–oxide interfacial structure that significantly enhances the electrocatalytic activity and stability of the SOEC cathodes. The La0.45Sr0.45Ti0.9Mn0.1Fe0.1O3−δ cathode exhibits exceptional electroreduction performance under the operating conditions of 850 °C, producing a CO yield of 5.3 mL min−1 cm−2 with a current efficiency of 97.1%. Even after 100 h of operation, the SOEC maintains excellent durability. This work provides new ideas for improving surface and interface engineering. [ABSTRACT FROM AUTHOR]

Conventional metal and cermet cathodes are easily oxidized during CO2 electrolysis, which seriously affects the electrolysis performance of electrolysis cells. The excellent durability and low cost of ceramic cathodes make them a promising alternative electrode. However, their catalytic activity is limited. In this work, we prepared a series of perovskite materials La0.6Sr0.4Cr1−xFexO3−δ (LSC1−xFx, x = 0–1) by synergistic doping at the B site to improve the catalytic activity. Replacing Cr with Fe can increase the concentration of low-valent Fe ions linked to oxygen vacancies, which leads to an increase in oxygen vacancies and thus improves the activity of CO2 electrolysis. Among the LSC1−xFx (x = 0–1) cathode materials, the LSC0.25F0.75 sample exhibits the highest electrochemical catalytic activity with a CO production rate of 5.32 mL min−1 cm−2 at 1.6 V and 850 °C, which is about 5 times that of other LSC cathode materials. In addition, its current efficiency can reach 96.4% during electrolysis of CO2. The electrolytic performance remained stable during the high temperature test for up to 100 h, further demonstrating its excellent thermal stability. [ABSTRACT FROM AUTHOR]

Traditional metal and cermet cathodes are easily oxidized when performing CO2 electrolysis without flowing reducing gas, resulting in the degradation of the electrolysis performance. Ceramic cathodes would demonstrate durable performance but their catalytic activity is normally limited. Here we engineer the perovskite La0.6Sr0.4Co1−xFexO3−δ (LSC1−xFx, x = 0–1) with synergistic doping in the B site to tailor the catalytic activity. In this work, we synthesize perovskite materials LSC1−xFx and explore their electrochemical performance. The replacement of Co with Fe increases the concentration of low valence Fe ions linked to oxygen vacancies and improves the catalytic activity for CO2 electrolysis. The LSC0.2F0.8 cathode has the highest electrochemical performance with a current density of 0.92 A cm−2 and a CO production of 5.49 ml min−1 cm−2 at 1.6 V and 850 °C. We show the excellent chemical stability in CO2 electrolysis through continuous operation for 100 h. This work provides a new idea for improving the catalytic activity and stability of perovskite cathode materials in solid oxide electrolysis cells. [ABSTRACT FROM AUTHOR]

Traditional metal and metal cermet cathodes are easy to be oxidized when operating with pure CO2 electrolysis, which therefore leads the degradation of electrolysis performance. Redox stable ceramic cathode provides alternative to achieve direct electrolysis of CO2; however, they show very limited catalytic activity toward CO2 splitting. In this work, we prepare perovskite materials La0.75Sr0.25Cr0.5Fe0.5+xO3−δ (LSCrFx, x = 0–0.1) through synergistic doping and treat them in H2/Ar to exsolve metallic Fe nanoparticles on LSCF scaffolds to enhance the catalytic activity. With the exsolution of iron nanoparticles, the cathode performance is enhanced by ~ 4–5 times with the CO product of 5.88 mL min−1 cm−2 and the current efficiency of ~ 97.5%. We further demonstrate the excellent thermal stability of CO2 electrolysis even after a continuous operation of 60 h and 6 redox cycles. This inspires exsolving metal nanoparticles over perovskite surface as a new technology for simultaneously enhancing catalytic activity and stability. [ABSTRACT FROM AUTHOR]

We have previously reported the electrochemical reduction of CO 2 to CO with simultaneous steam electrolysis in a proton conducting solid oxide electrolyzer (PCSOE); however, the conventional Ni-cermet electrode is rapidly oxidized by H 2 O/CO 2 in cathode that causes cell performance degradation. In this work, we report a novel symmetrical PCSOE with redox-stable LSCM ((La 0.75 Sr 0.25 ) 0.95 Cr 0.5 Mn 0.5 O 3−δ ) electrode for the electrochemical conversion of CO 2 /H 2 O into syngas (CO/H 2 ). The Ru catalyst is impregnated to LSCM to improve electrode activity. Electrochemical measurements demonstrate that the CO 2 is electrochemically reduced to syngas (CO/H 2 ) with simultaneous steam electrolysis. The loading of Ru catalyst promotes the electrochemical process with higher Faradic efficiency while induces a more competitive process of hydrogen evolution at 700 °C. [ABSTRACT FROM AUTHOR]

The solid oxide CO 2 electrolyzer has the potential to provide storage solutions for intermittent renewable energy sources as well as to reduce greenhouse gas emissions. One of the key challenges remains the poor adsorption and activity toward CO 2 reduction on the electrolyzer cathode at typical operating conditions. Here, we show a novel approach in tailoring a perovskite titanate (La, Sr)TiO 3+δ cathode surface, by the in situ growing of SrO nanoislands from the host material through the control of perovskite nonstoichiometry. These nanoislands provide very enhanced CO 2 adsorption and activation, with stability up to 800 °C, which is shown to be in an intermediate form between carbonate ions and molecular CO 2 . The activation of adsorbed CO 2 molecules results from the interaction of exsolved SrO nanoislands and the defected titanate surface as revealed by DFT calculations. These cathode surface modifications result in an exceptionally high direct CO 2 electrolysis performance with current efficiencies near 100%.