Enhanced Hydrogen Permeability of Mixed Protonic–Electronic Conducting Membranes through an In‐Situ Exsolution Strategy

Abstract Mixed protonic–electronic conducting (MPEC) ceramic membranes with high H₂ permeability and stability are significant for practical H₂ separation. CO₂‐tolerant lanthanum tungstate oxides have received much attention, but their low H₂ permeability is their main problem for membrane applications. Herein, an efficient in‐situ exsolution strategy is proposed to enhance the H₂ permeability and CO₂ stability of lanthanum tungstate‐type membranes. During H₂ permeation, the catalytic Pd nanoparticles are in‐situ generated from the bulk oxide lattices and dispersed evenly on the membrane surfaces, which greatly promotes the H₂ surface exchange kinetics. Also, the protonic conductivity of the membranes is effectively improved through the introduction of Pd. Consequently, the H₂ permeation flux is increased by 3.5 times and a maximum H₂ flux of 1.3 mL min⁻¹ cm⁻² is achieved at 1000 °C through the La_5.5(W_0.6Mo_0.4)_0.95Pd_0.05O_11.25‐δ (LWMPd) membrane. The LWMPd membrane shows outstanding long‐term chemical stability during 300 h continuous operation in a CO₂‐containing atmosphere. Therefore, this in‐situ exsolution formation of Pd nanoparticles provides effective guidance for developing competitive MPEC membranes for H₂ separation and purification.