Mixed protonic-electronic conducting ceramic membranes for hydrogen separation: A review on recent advances in structure optimization and preparation

The mixed protonic-electronic conducting (MPEC) ceramic membrane is crucial in hydrogen separation technology due to its excellent hydrogen selectivity, high-temperature stability, and cost-effectiveness. This review offers a comprehensive analysis of various properties and structures of ceramic membranes, including recent optimization strategies. It highlights innovations such as emerging novel materials, modified designs, dual-phase membranes, independent channel structures, external short-circuit structures, asymmetric structures, and hollow fibers. Additionally, this review examines the performance and potential of electrochemical hydrogen pumps (EHPs) in enhancing the membrane hydrogen permeability. Methods for precursor preparation and sintering are also discussed to further improve membrane performance. The review identifies existing challenges, including limited structural innovation and high EHP energy consumption, and underscores the need for advanced preparation techniques. It offers insights into addressing the experimental limitations in continuous hydrogen purification and industrial membrane production. Finally, the review outlines future research directions, such as developing thinner membrane preparation methods, exploring metal cation doping effects, optimizing costefficiency balance of EHPs, coupling membrane-based EHPs with other hydrogen technologies, and integrating emerging technologies like 3D printing and AI-based control systems.