Design of CO₂-Resistant High-Entropy Perovskites Based on Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ Materials

High-entropy perovskite materials (HEPMs), characterized by their multi-element composition and highly disordered structure, can incorporate multiple rare earth elements at the A-site, producing perovskites with enhanced CO₂ resistance, making them stay high performance and structurally stable in the CO₂ atmosphere. However, this modification may result in reduced oxygen permeability. In this study, we investigated La_0.2Pr_0.2Nd_0.2Ba_0.2Sr_0.2Co_0.8Fe_0.2O_3-δ (L_0.2M_1.8) high-entropy perovskite materials, focusing on enhancing their oxygen permeability in both air and CO₂ atmospheres through strategic design modifications at the B-sites and A/B-sites. We prepared Ni-substituted La_0.2Pr_0.2Nd_0.2Ba_0.2Sr_0.2Co_0.7Fe_0.2Ni_0.1O_3-δ (L_0.2M_1.7N_0.1) HEPMs by introducing Ni elements at the B-site, and further innovatively introduced A-site defects to prepare La_0.2Pr_0.2Nd_0.2Ba_0.2Sr_0.2Co_0.7Fe_0.2Ni_0.1O_3-δ (L_0.1M_1.7N_0.1) materials. In a pure CO₂ atmosphere, the oxygen permeation flux of the L_0.1M_1.7N_0.1 membrane can reach 0.29 mL·cm⁻²·min⁻¹. Notably, the L_0.1M_1.7N_0.1 membrane maintained a good perovskite structure after stability tests extending up to 120 h under 20% CO₂/80% He atmosphere. These findings suggest that A-site-defect high-entropy perovskites hold great promise for applications in CO₂ capture, storage, and utilization.