Multidimensional Engineering of Mixed Protonic‐Electronic Conducting Membranes with Excellent Hydrogen Separation Performance

Abstract Both high H ₂ permeability and good chemical stability (particularly in CO ₂ ‐containing atmospheres) of mixed protonic‐electronic conducting (MPEC) membranes are the critical requirements toward practical H ₂ separation processes. Herein, a multidimensional engineering strategy is proposed to develop an efficient fluorine (F)‐doped asymmetric lanthanum tungstate‐type La _5.5 (W _0.6 Mo _0.4 ) _0.95 Pd _0.05 O _11.25‐δ F _0.05 (LWMPdF _0.05 ) membrane from both micro and macro levels. At the micro level, the introduction of the strongest electronegative anion of F and in‐situ exsolution of Pd nanoparticles strategies are employed to enhance the membrane bulk diffusion and surface exchange kinetics, respectively. At the macro level, an asymmetric configuration is constructed via spin coating, consisting of a thin dense layer (≈8 µm) supported on a porous substrate. The thin dense layer significantly reduces bulk diffusion resistance, while the porous substrate with a large specific surface area effectively promotes surface exchange processes. As a result, this developed asymmetric LWMPdF _0.05 membrane exhibits an unprecedented H ₂ flux of 2.5 ± 0.2 mL min ⁻¹ cm ⁻² at 1000 °C and excellent chemical stability during 520 h of continuous operation at 850 °C, demonstrating great potential for practical H ₂ separation applications.