Reversible solid oxide electrochemical cells with regulated oxygen trapping nano-dots on Ni-Fe fuel electrode

[Display omitted] •Solid direct injection via ultrasonic spraying achieved high-quality LSGM-based SOCs.•The La-doped ceria layer from ultrasonic spraying had higher density and lower tortuosity.•Convex CeO2 nanodots fabricated by USSP showcase remarkable oxygen-trapping capacity.•ReSOCs with Ni–Fe@Ceria-dot electrode achieved excellent performance and durability. Reversible Solid Oxide Electrochemical Cells (ReSOCs) have been affirmed as the next-generation, high-performance energy conversion and storage devices. However, ReSOCs still encounter various challenges, including poor performance in either fuel cell or electrolysis mode, the absence of a cost-effective and scalable manufacturing process, and flexible application (etc., NH3, C3H8). Herein, we have pioneered an innovative fuel electrode comprising a Ni-Fe bimetallic phase decorated with nanosized ceria, aiming to enhance both fuel cell and electrolysis performance. Furthermore, we have designed and validated a distinctive direct solid injection method utilizing the ultrasonic spraying process to decorate the Ni-Fe fuel electrode with nanosized ceria, showcasing a remarkable oxygen trapping capacity. This intricately regulated structure serves as a mechanism for trapping oxygen molecules on nano-ceria dots, facilitating an efficient migration pathway during surface reactions. Consequently, ReSOCs were demonstrated, achieving a maximum power density of 1.40 W cm−2 at 800 °C in fuel cell mode, and an exceptional electrolysis current density of 1.01 A cm−2 at 1.3 V. Additionally, ReSOCs showed durable operation for 500 h in both fuel and electrolysis cell mode.