KAIST researchers have made a significant breakthrough in the development of eco-friendly hydrogen filters, potentially revolutionizing clean energy production. This achievement, detailed in a recent study published in Nature Communications, introduces a novel approach to creating high-performance separation membranes that can selectively filter hydrogen with remarkable purity.
The research team, led by Professor Tae-Hyun Bae, has developed a membrane called ms-oDMB-DB50, which achieves a high bridge connectivity degree of 73%. This degree indicates the proportion of crosslinkers that are connected at both ends, forming complete pathways for hydrogen transport. By introducing hydrogen-selective transport pathways at the angstrom scale, the membrane demonstrates significantly improved hydrogen permeability and hydrogen/nitrogen selectivity compared to the original material, DB50.
One of the key innovations is the development of a new metric called the Bridge Connectivity Degree (BCD), which allows for the quantitative assessment of network completeness in polymer membranes. This metric overcomes the limitations of traditional indicators like the degree of crosslinking (CD) and effective crosslinking degree (ECD), which couldn't determine the formation of pores useful for separation.
The membrane's performance is further enhanced by the presence of numerous ultramicropores smaller than 3 Å, which carbon dioxide cannot access. This feature ensures that the membrane can selectively filter hydrogen while maintaining stability and durability. The research team employed a density-probe method using helium molecules, smaller than hydrogen, to experimentally verify the existence of these ultramicropores.
Moreover, the ms-oDMB-DB50 membrane operates stably for 100 hours without any loss of performance, showcasing its robust durability. Its tensile strength, approximately twice that of previously reported high-performance polymer membranes, further confirms its suitability for industrial processes.
Dr. Hongju Lee, a postdoctoral researcher and first author of the study, emphasizes the significance of defining network completeness as a quantitative value and directly linking it to separation performance. This approach, he suggests, could extend the reticular synthesis design principle, traditionally used for inorganic molecular sieves, to polymer membranes.
Professor Tae-Hyun Bae highlights the success of stitching polymer chains with crosslinkers that fit together like Lego blocks, creating a network that selectively allows small hydrogen gas molecules to pass through. This breakthrough not only addresses the challenge of separating hydrogen with high purity from mixed gases but also opens up new possibilities for the widespread use of hydrogen as a clean energy source.
The research was supported by the 2025 Global C.L.E.A.N. Project and the Mid-Career Researcher Program under the Basic Research Program, funded by the Ministry of Science and ICT. The study's publication in Nature Communications underscores the potential impact of this research on the future of clean energy technologies.
