Dual-functional engineering of Fe nanoparticles and oxygen vacancies in Sr1.9Fe1.5Mo0.5O6−δ perovskites for high-efficiency CO2/H2O co-electrolysis

The development of high-performance perovskite cathodes is critical for advancing carbon-neutral energy technologies through efficient CO2-to-fuel conversion in solid oxide electrolysis cells (SOECs). In this work, we present a groundbreaking dual-functional engineering strategy that simultaneously achieves in situ exsolution of Fe nanoparticles and oxygen vacancy formation in Sr2−xFe1.5Mo0.5O6−δ perovskites. By correlating A-site deficiency with tailored reduction protocols, we demonstrate precise control over Fe nanoparticle density and the oxygen vacancy concentration, synergistically addressing the dual bottlenecks of CO2 activation kinetics and ionic transport limitations. The engineered cathode delivers record-breaking performance: −0.92 A cm−2 (H2O electrolysis@800 °C/1.3 V) and −1.58 A cm−2 (co-electrolysis@800 °C/1.5 V), surpassing that of benchmark perovskites. The dual-modified architecture demonstrates unprecedented durability with 120 h of steam electrolysis and 80 h of co-electrolysis operation at 750 °C/0.5 A cm−2. This work establishes a materials design paradigm that directly bridges atomic-scale defect engineering with macroscale energy conversion efficiency, offering a scalable pathway for transforming industrial CO2 emissions into renewable fuels.