A High-Entropy Layered Perovskite Coated with In-situ Exsolved Core-shell CuFe@FeO x Nanoparticles for Efficient CO 2 Electrolysis.

Solid oxide electrolysis cells (SOECs) are promising energy conversion devices capable of efficiently transforming CO 2 into CO, reducing CO 2 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 CO 2 electrolysis consisting of high-entropy Pr 0.8 Sr 1.2 (CuFe) 0.4 Mo 0.2 Mn 0.2 Nb 0.2 O 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 CO 2 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 CO 2 . 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 CO 2 adsorption, dissociation, and reduction. This article is protected by copyright. All rights reserved.