笔辞蝉迟罢颈尘别：2/26/2026
Recently, the research team led by Professor Xuezhong He at the Guangdong Technion – Israel Institute of Technology (GTIIT) reported a molecular design strategy. By developing a rigid, asymmetric copolyimide precursor and precisely controlling its carbonization behavior, the team fabricated an adsorption-enhanced CMS membrane with record-breaking CO2 separation performance, which provides crucial material support for efficient carbon capture and clean energy production.
The work, entitled “Adsorption-enhanced carbon membranes derived from copolyimide for ultrafast subangstrom discriminating CO2 separation”, was published in Science Advances (IF: 12.5; DOI: 10.1126/sciadv.adv8650). Dr. candidate Wang Kaifang is the first author of the paper, and Prof. Xuezhong He serves as the sole corresponding author.
Team Photo
As a flagship journal in the Science family, Science Advances is dedicated to publishing high-quality research across all scientific fields. It is renowned for its rigorous peer review and outstanding academic influence. Publishing a paper in this journal signifies that a researcher's work has gained recognition from the global scientific community.
About the research
Carbon dioxide (CO2) separation and capture play a central role in addressing climate change and enabling low-carbon energy systems. Conventional chemical absorption technologies, although widely implemented, suffer from high energy consumption, complex process design, and substantial operational costs. These limitations have driven intense interest in membrane-based gas separation technologies, which offer intrinsic advantages such as high energy efficiency, modularity, and phase-change-free operation. Despite these advantages, polymeric membranes are fundamentally constrained by the well-known permeability–selectivity trade-off: increasing gas permeability typically leads to a loss in separation selectivity, and vice versa. Overcoming this intrinsic limitation remains one of the most critical challenges in membrane science, particularly for CO2 capture and removal from gas mixtures.
Carbon molecular sieve (CMS) membranes, formed by carbonizing polymer precursors, have emerged as a promising alternative owing to their rigid carbon frameworks and angstrom-scale pore structures. In principle, CMS membranes can discriminate gas molecules based on subtle size differences. However, conventional CMS membranes are commonly derived from symmetric polyimide precursors, which tend to form overly dense, graphitized carbon structures during high-temperature carbonization. This excessive densification severely restricts CO2 transport, preventing the simultaneous realization of high permeability and high selectivity.
The research team reported a molecular design strategy that overcomes these limitations. By developing a rigid, asymmetric copolyimide precursor and precisely controlling its carbonization behavior, the team fabricated an adsorption-enhanced CMS membrane with record-breaking CO2 separation performance.
Molecular Innovation: The 6FDA–DAM–AB-TFMB Copolyimide
The key innovation lies in the rational design of a 6FDA–DAM–AB-TFMB copolyimide precursor. The incorporation of the AB-TFMB monomer introduces a rigid, non-coplanar molecular geometry, while simultaneously embedding volatile functional groups such as –CH3 and –CF3 into the polymer backbone. During carbonization, these functional groups undergo controlled decomposition, releasing small gas molecules (e.g., H2, CO2, and CH4). This process effectively suppresses excessive stacking and densification of carbon layers, enabling the formation of precisely tunable ultramicropores (4–7 ?). At the same time, the rigid backbone preserves the structural integrity of the membrane, resulting in a carbon framework with a bimodal pore size distribution:
· Micropores (7–20 ?) facilitate rapid gas transport,
· Ultramicropores (4–7 ?) provide sub-angstrom molecular discrimination.
This hierarchical pore architecture allows the membrane to achieve both high gas flux and high separation resolution within a single material system.
Mechanistic Insights into Carbonization and Gas Transport
To elucidate the pore formation mechanism and gas transport behavior, the researchers employed a combination of in situ thermogravimetric analysis coupled with mass spectrometry (TGA-MS), thermogravimetric–infrared spectroscopy (TGA-FTIR), and molecular dynamics simulations. These complementary techniques revealed a multistep carbonization pathway involving polymer chain scission, aromatization, and progressive pore generation. Importantly, the study demonstrates that gas transport in this CMS membrane is governed by a synergistic mechanism combining adsorption selectivity and molecular sieving. CO2 molecules preferentially adsorb onto the carbon surface due to their higher quadrupole moment and affinity for the carbon matrix, while the sub-angstrom ultramicropores effectively exclude larger gas molecules such as N2 and CH4. This dual mechanism enables unprecedented discrimination at the molecular scale.
Record-High CO2 Separation Performance
As a result of this rational structural and mechanistic design, the CMS membranes exhibit outstanding separation performance. Membranes carbonized at 800 °C achieve a CO2 permeability of 15,700 Barrer, along with CO2/N2selectivity of 63 and CO2/CH4 selectivity of 52. These values collectively surpass the 2019 Robeson upper bounds for polymeric membranes. Moreover, the membranes maintain excellent performance stability after physical aging, highlighting their robustness under practical operating conditions. Such a combination of high permeability, high selectivity, and long-term stability is rarely achieved in CMS membranes and represents a significant step toward industrial implementation.
Scientific and Technological Significance
This work establishes a new paradigm for CMS membrane design by demonstrating that precise control of precursor molecular architecture can dictate pore evolution during carbonization. By enabling “designable pore engineering” at the sub-nanometer and atomic scales, the study breaks the long-standing permeability–selectivity trade-off that has constrained membrane technologies for decades. From a scientific perspective, the research provides the first systematic insight into how volatile functional groups embedded in rigid, asymmetric copolyimide backbones cooperatively regulate pore development in carbon membranes. From a technological standpoint, the ability to integrate high permeability and high selectivity within a single CMS membrane opens new opportunities for energy-efficient gas separation.
Looking ahead, the research team is actively advancing the fabrication of hollow-fiber CMS membranes to increase packing density and mechanical robustness, paving the way for large-scale applications in CO2 capture, natural gas sweetening, and biogas upgrading.
Paper link
https://www.science.org/doi/10.1126/sciadv.adv8650
Scholar Profile
Xuezhong He, Associate Professor and PhD Supervisor in Chemical Engineering at GTIIT, holds a Ph.D. in Chemical Engineering from the Norwegian University of Science and Technology (2011). His research focuses on gas membrane separation, including carbon capture, hydrogen separation, and natural gas purification. He is a recipient of the NSFC Fund for International Excellent Young Scientists and has been consistently ranked among the "World's Top 2% Scientists."
He has published over 100 papers in leading journals (e.g., Nat. Commun., Sci. Adv., Adv Sci., J. Membr. Sci., AIChE J.), with over 6,300 citations and an H-index of 41. He holds 4 patents and has delivered more than 40 presentations at international conferences. He serves on the editorial boards of Separation and Purification Technology and Carbon Capture Science & Technology.
He has led or participated in more than 10 projects funded by organizations such as the NSFC, the National Key R&D Program of China (Sino-Israel Joint Research Project), the Guangdong Natural Science Foundation, Science, Technology and Innovation Commission of Shenzhen Municipality, the Shantou Science and Technology Bureau, the Research Council of Norway (RCN), and the EU FP6 program. He has collaborated closely with industry partners including Equinor (Norway), NORCEM Cement Plant, Air Products, CIMC Offshore Engineering, and Pure Water No.1, and has been involved in carbon capture, utilization, and storage (CCUS) research initiatives at the NORCEM cement plant and CIMC offshore vessel platforms.
Text: Xuezhong He, GTIIT News & Public Affairs
Photos: provided by Xuezhong He
