Spatially Confined Palladium Islands in Layered Double Hydroxide/Zeolitic Imidazolate Framework Hybrid Membranes With Nanocorridor for Enhanced H ₂ /CH ₄ Separation Performance

Due to lower energy consumption, great separation performance, and simple operation process, membrane technology plays an important role in gas separation. However, separation membranes often face a trade-off between permeance and selectivity. For instance, the pure layered double hydroxide (LDH) or metal organic framework (MOF) membranes exhibit high gas permeance but suffer from low selectivity. However, conventional Pd membranes typically have a thickness exceeding 50 μm, resulting in high costs and limited permeance. This article develops a novel strategy to fabricate a CoAl LDH/zeolitic imidazolate framework (ZIF)-67 heterostructure on a polydopamine-modified substrate, following by the infiltration of Pd nanoparticles (Pd NPs) into the LDH/ZIF framework via magnetron sputtering, resulting in a well-integrated LDH/ZIF@Pd membrane for highly efficient H₂/CH₄ separation. In this architecture, the LDH sheets not only create nanocorridors for gas permeation but also provide the nucleation sites for ZIF grains. The incorporated Pd NPs and LDH/ZIF network form a well-integrated heterostructure, which endows the LDH/ZIF@Pd hybrid membrane with exceptional comprehensive performance, achieving H₂/CH₄ selectivity of 48.3 and ultrahigh H₂ permeance of 8.4 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mo>×</mml:mo></mml:mrow> <mml:annotation>$\times$</mml:annotation></mml:semantics> </mml:math> 10⁵ GPU (75°C, 1 bar). This result sets a new benchmark for membrane-based gas separation, demonstrating outstanding potential for advanced hydrogen purification and sustainable energy applications.