Single-Atom Separation of Gas in Oriented Zeolite Membranes

A single atom, with maximized atomic utilization and a tailored electronic structure, serves as a promising selective site for achieving ultrahigh selectivity in separation membranes. However, single-atom synthesis within membrane pores with the required chemical specificity for separation remains challenging. Here, we demonstrate single-atom gas separation using Ni single atoms confined in the 10-membered ring channels of (h0h)-oriented MFI zeolite membranes, which serve as intrinsic ultraselective sites for CO2. At an ultralow Ni loading of 0.037 wt %, the membrane achieves an ultrahigh H2/CO2 separation factor of 596, along with excellent H2 permeability of 1924 Barrer, while maintaining stable operation for over 200 h. This performance compares favorably with that of state-of-the-art membranes. Mechanistic studies reveal that hybridization of Ni–O orbitals preferentially interacts with CO2, in contrast to the weak physisorption of H2. This work establishes an atomic-level recognition mechanism in nanoporous architectures and offers new design principles for energy-critical gas separations.