In situ exsolved M-Ru bimetallic sites with fine-tuned charge distribution for enhanced CO2/H2O co-electrolysis performance in La0.75Sr0.25CrO3-δ-based SOEC cathodes

Abstract

Advancing the co-electrolysis of CO 2 /H 2 O in solid oxide electrolysis cells (SOECs) critically relies on the development of cathode with high efficiency and excellent stability. This study designs high-performance perovskite oxide cathode materials (La 0.75 Sr 0.25 Cr 0.7 M 0.2 Ru 0.1 O 3-δ , LSCMR; M = Fe, Co, Ni) via in-situ exsolution of bimetallic nanoparticles, aiming to elucidate the influence of metal alloy on electrocatalytic activity. The materials underwent systematic characterization and electrochemical testing. Results demonstrate that the LSCFR (M = Fe) cathode exhibited optimal performance with superior gas diffusion and surface reaction kinetics, achieving 1.70 A cm −2 at 850 °C at 1.5 V with approximately 30% enhancement after exsolution, along with excellent durability over 500 h. Density functional theory (DFT) calculations indicate that the electronegativity difference between M and Ru induces electron transfer, which lowers the Ru d-band center and optimizes adsorption energy. The Fe 4 Ru site exhibits the strongest H 2 O adsorption energy of −0.98 eV, significantly enhancing water dissociation activity. Choosing a metal M with a larger electronegativity difference relative to Ru can effectively regulate the charge distribution of active sites and thus may improve catalytic performance. This work provides an effective strategy for preparing high-performance electrodes via in-situ exsolution.