Recent breakthroughs in cathode of protonic ceramic fuel cells: Materials, functionalization, and future perspectives

Hydrogen stands as a promising energy carrier that plays a pivotal role in addressing global sustainability and achieving carbon neutrality. The conversion of hydrogen energy through fuel cells has emerged as a central technology in this pursuit. Notably, protonic ceramic fuel cells (PCFCs) hold potential for the future hydrogen energy ecosystem, owing to their impressive energy conversion efficiencies at low-to-intermediate temperatures (300–750°C). It is becoming increasingly evident that the development of PCFC technology relies on advancements in the cathode, as oxygen-involved reactions often exhibit sluggish kinetics. In this comprehensive review, we aim to provide an overview of the current state of knowledge concerning the design of advanced cathodes for PCFCs. This includes discussing key descriptors for cathodes, methods for characterizing material properties, and functionalization techniques to enhance electrode performance. Finally, we present insights into future research directions.