Defence Nannan Li: "Functionalization of Steam/Air Electrodes for Intermediate Temperature Protonic Ceramic Cells"
Promotors: First promotor: Prof Vassilis Kyriakou, Second promotor: Prof Paolo Pescarmona
Abstract: Protonic ceramic electrochemical cells (PCECs) offer a promising pathway for efficient green hydrogen production and reversible energy conversion at intermediate temperatures. However, their practical application remains limited by challenges associated with electrolyte–electrode interfaces, sluggish electrode reaction kinetics, and insufficient electrode stability. This thesis systematically investigates material and interface engineering strategies to enhance the electrochemical performance and durability of PCECs.
First, nitric acid treatment was employed to optimize the electrolyte surface, effectively reducing ohmic and polarization resistances and improving cell performance. Subsequently, Ca doping of PrNi0.5Co0.5O3-δ (PNC) was investigated to enhance ionic conductivity and oxygen evolution reaction activity, leading to improved steam electrolysis performance at 400–650 °C. Furthermore, a novel cation-diffusion-driven in-situ exsolution strategy was demonstrated, enabling the formation of catalytically active Pr₆O₁₁ nanoparticles on electrode surfaces. This approach significantly enhanced electrocatalytic activity, achieving faradaic efficiencies exceeding 95% and stable operation over 500 h. Finally, electrospinning was employed to fabricate porous PCNC nanofiber electrodes with improved oxygen exchange kinetics, mass transport, and triple-conducting properties, resulting in enhanced reversible cell performance and durability.
Overall, this thesis demonstrates that combining electrolyte interface optimization, compositional modification, surface reconstruction, and microstructural engineering provide effective strategies for overcoming key limitations of PCECs. These findings offer valuable insights into the development of high-performance protonic ceramic electrochemical cells for sustainable hydrogen production and energy conversion.