Cr doping regulates FeNi alloy nanoparticle exsolution on Sr2Fe1.1Ni0.2Cr0.2Mo0.5O6−δ cathode to facilitate CO2 electrolysis

Abstract

Metal exsolution in perovskite oxides has emerged as an effective way to boost CO₂ electrolysis activity in solid oxide electrolysis cells (SOECs). It is crucial to precisely tailor the exsolution characteristics to optimize the catalytic functionality and boost the catalytic activity. Herein, we reveal that Cr cation doping effectively modifies the crystal defects and regulates the metal exsolution of Sr₂Fe_1.1Ni_0.2Cr_0.2Mo_0.5O_6−δ (SFNCM). FeNi alloy nanoparticles with an average particle size of ∼10 nm and a particle density exceeding 1500 µm⁻² were exsolved on the surface of SFNCM perovskite, which increases the active sites and enhances CO₂ electrolytic activity. The SFNCM-based SOEC decorated with abundant FeNi alloy nanoparticles achieves a high current density of 2.57 A cm⁻² at 1.6 V, superior to other Sr₂Fe_1.3Ni_0.2Mo_0.5O_6−δ counterparts. The experimental and theoretical calculation results demonstrate the controllability of the exsolution via engineering of the perovskite structural feature. This work offers a new perspective on the lattice doping strategy for the regulation of metal exsolution.