Atomic layer deposited aluminium oxide membranes for selective hydrogen separation through molecular sieving.

Ultra-thin membranes have significant potential for the gas separation. However, the fabrication of ultra-thin membrane with high selectivity and permeance remains a challenge. Herein, we develop a high-performance hydrogen separation membrane using atomic layer deposition (ALD) method to deposit ultra-thin Al 2 O 3 layer (ALD-Al 2 O 3) on a porous anodic aluminum oxide (AAO) support. The pore openings of the AAO substrate were fully covered, but not sealed, by the Al 2 O 3 overlayer after 260 ALD cycles. Due to the low deposition temperature (50 °C), angstrom-scale pores were formed within the Al 2 O 3 overlayer. Single gas permeance results revealed that the size of the pores to be smaller than 0.364 nm, but larger than the kinetic diameter of molecular H 2 (0.289 nm). This membrane at room temperature, exhibits high H 2 permeance of ∼3.03 × 10−7 mol m−2 s−1 Pa−1 and high H 2 selectivity for H 2 /CO 2 (5148.2), H 2 /O 2 (120.7), H 2 /N 2 (161.5) and H 2 /CH 4 (219.5), showing great potential for industrial H 2 purification and recovery. [Display omitted] • Ultra-thin hydrogen separation membrane was prepared by atomic layer deposition. • Ultra-thin membrane shows ultrahigh gas-pair selectivity. • Molecular sieving effect results in the high gas separation performance. [ABSTRACT FROM AUTHOR]