A High‐Entropy Layered Perovskite Coated with In‐situ Exsolved Core‐shell CuFe@FeO_x Nanoparticles for Efficient CO₂ Electrolysis

Abstract

Solid oxide electrolysis cells (SOECs) are promising energy conversion devices capable of efficiently transforming CO₂ into CO, reducing CO₂ emissions, and alleviating the greenhouse effect. However, the development of a suitable cathode material remains a critical challenge. Here we report a new SOEC cathode for CO₂ electrolysis consisting of high‐entropy Pr_0.8Sr_1.2(CuFe)_0.4Mo_0.2Mn_0.2Nb_0.2O_4‐δ (HE‐PSCFMMN) layered perovskite uniformly coated with in‐situ exsolved core‐shell structured CuFe alloy@FeO_x (CFA@FeO) nanoparticles. Single cells with the HE‐PSCFMMN‐CFA@FeO cathode exhibits a consistently high current density of 1.95 A cm⁻² for CO₂ reduction at 1.5 V while maintaining excellent stability for up to 200 h under 0.75 A cm⁻² at 800 °C in pure CO₂. In‐situ XPS and density functional theory (DFT) calculations confirm that the exsolution of CFA@FeO nanoparticles introduces additional oxygen vacancies within HE‐PSCFMMN substrate, acting as active reaction sites. More importantly, the abundant oxygen vacancies in FeO_x shell, in contrast to conventional in‐situ exsolved nanoparticles, enable the extension of the triple‐phase boundary (TPB) from the CFA@FeO/HE‐PSCFMMN interface to the entire FeO_x shell, thereby enhancing the kinetics of CO₂ adsorption, dissociation, and reduction.

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