Highly Stable and Efficient Catalyst with In Situ Exsolved Fe–Ni Alloy Nanospheres Socketed on an Oxygen Deficient Perovskite for Direct CO<sub>2</sub> Electrolysis

Abstract

The massive emission of carbon dioxide (CO<sub>2</sub>), the major portion of greenhouse gases, has negatively affected our ecosystem. Developing new technologies to effectively reduce CO<sub>2</sub> emission or convert CO<sub>2</sub> to useful products has never been more imperative. In response to this challenge, we herein developed novel in situ exsolved Fe–Ni alloy nanospheres uniformly socketed on an oxygen-deficient perovskite [La­(Sr)­Fe­(Ni)] as a highly stable and efficient catalyst for the effective conversion of CO<sub>2</sub> to carbon monoxide (CO) in a high-temperature solid oxide electrolysis cell (HT-SOEC). The symmetry between the reduction and reoxidation cycles of this catalyst indicates its good redox reversibility. The cathodic reaction kinetics for CO<sub>2</sub> electrolysis is significantly improved with a polarization resistance as low as 0.272 Ω cm<sup>2</sup>. In addition, a remarkably enhanced current density of 1.78 A cm<sup>–2</sup>, along with a high Faraday efficiency (∼98.8%), was achieved at 1.6 V and 850 °C. Moreover, the potentiostatic stability test of up to 100 h showed that the cell was stable without any noticeable coking in a CO<sub>2</sub>/CO (70:30) flow at an applied potential of 0.6 V (vs OCV) and 850 °C. The increased oxygen vacancies together with the in situ exsolved nanospheres on the perovskite backbone ensures sufficiently active sites and consequently improves the electrochemical performance for the efficient CO<sub>2</sub> conversion. Therefore, this newly developed perovskite can be a promising cathode material for HT-SOEC. More generally, this study points to a new direction to develop highly efficient catalysts in the form of the perovskite oxides with perfectly in situ exsolved metal/bimetal nanospheres

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