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

Both high H₂ permeability and good chemical stability (particularly in CO₂-containing atmospheres) of mixed protonic-electronic conducting (MPEC) membranes are the critical requirements toward practical H₂ separation processes. Herein, a multidimensional engineering strategy is proposed to develop an efficient fluorine (F)-doped asymmetric lanthanum tungstate-type La_5.5(W_0.6Mo_0.4)_0.95Pd_0.05O_11.25-δF_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 H₂ 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 H₂ separation applications.