Optimizing water electrolysis activity in Mo-doped Sr2FeCoO6-δ perovskites by balancing oxygen vacancies and structural stability

Abstract

Perovskite-based solid oxide electrolysis cells (SOECs) are promising for efficacious hydrogen production. This work explored how varying molybdenum (Mo) content impacts the structure and performance of Sr2FeCo1-xMoxO6-δ (SFCMx) perovskites for SOEC water electrolysis. SFCMx (x = 0.1–0.5) were synthesized via sol-gel method and incorporated into symmetrical cells. Electrolysis testing showed SFCM0.3 had the highest activity, achieving 2.09 A cm−2 at 2.0 V and 800 °C, compared to 0.964 and 0.847 A cm−2 for SFCM0.1 and SFCM0.5 respectively. This optimal performance with 0.3 Mo doping was put down to simultaneous variations in oxygen vacancy concentration and crystalline structure stability. Lower Mo doping accelerated charge transfer but destabilized the structure, while higher doping stabilized the cubic perovskite structure but reduced vacancies and electrocatalytic activity. This work demonstrates that balancing activity and stability by optimizing dopant concentration is critical to maximize SOEC performance. This provides new insights for enhancing water electrolysis through controlled doping and tuning of the perovskite structure.