Thermally regulated gating phenomenon in bio-derived ultra-narrow nanoporous carbon for enhancing hydrogen isotope separation

Abstract

The temperature-triggered gating in flexible nanoporous frameworks exhibits dynamic nanopore regulation under external stimuli, leading to optimum pore sizes and enhanced selectivity for isotopologue separation. In this work, we report one of the very rare observations of temperature-responsive gating in efficient bio-derived ‘nanoporous carbon’ material. The distinctive characteristics of this material, such as its suitable pore sizes for Kinetic Quantum Sieving (KQS) that lead to strong diffusion limitation, as well as its capacity to operate at higher temperatures, overcome the limitations of existing crystalline porous materials. It is remarkable that this activated carbon derived from biological sources, even without any strong binding sites, can release hydrogen isotopologues at a higher temperature of 180 K in comparison to MOF-74(Ni), which possesses many open metal sites but releases mostly at 90–100 K. The separation performance is also demonstrated to reach up to 120 K, and only six separation cycles are needed to enrich from a low concentration of 4 % to –92 % D2 in a mixture of deuterium (D2/H2). This finding suggests that inexpensive porous carbon's thermal pore size modulation can significantly increase the operating temperature for precise separation of hydrogen isotopologues. © 2024 Elsevier Ltd