Cheng Chi, Kim Lohyun, Persad Aaron H, Chow Chun Man, Karnik Rohit
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia.
Nat Commun. 2025 Jul 1;16(1):6052. doi: 10.1038/s41467-025-61110-8.
Temperature-dependent, selective molecular diffusion through porous materials is crucial for membrane separations and is typically modeled as an Arrhenius-type activated process. Although this dependence can be described phenomenologically by an activation energy, tracing its molecular origins is often difficult, hindering robust membrane design for practical applications. Here, we investigate gas transport across monolayer nanoporous graphene membranes and observe significant, reversible, temperature-robust, and gas species-selective activated transport, with increased selectivity at rising temperatures, unlike many conventional membranes. Combined experiment and modelling trace this behavior to graphene nanopore edge functional groups, whose thermal fluctuations modulate effective pore size. This activated transport remains stable with aging over 1 year and shows selectivity exceeding 70 for hydrogen/hydrocarbon mixture separation at 220 °C, representative of dehydrogenation reactor temperatures. Our results demonstrate the thermal and long-term robustness of nanoporous graphene membranes, suggesting potential for precise engineering of nanopore surface chemistries in membranes for challenging molecular separations.
通过多孔材料的温度依赖性选择性分子扩散对于膜分离至关重要，通常被建模为阿累尼乌斯型活化过程。尽管这种依赖性可以通过活化能从现象学上进行描述，但追溯其分子起源往往很困难，这阻碍了面向实际应用的稳健膜设计。在此，我们研究了气体在单层纳米多孔石墨烯膜上的传输，并观察到显著的、可逆的、对温度稳定且对气体种类有选择性的活化传输，与许多传统膜不同的是，温度升高时选择性增加。实验与建模相结合将这种行为追溯到石墨烯纳米孔边缘官能团，其热涨落调节有效孔径。这种活化传输在长达一年的老化过程中保持稳定，并且在220°C下对氢气/烃类混合物分离的选择性超过70，这是脱氢反应器温度的典型代表。我们的结果证明了纳米多孔石墨烯膜的热稳定性和长期稳定性，表明在用于具有挑战性的分子分离的膜中对纳米孔表面化学进行精确工程设计具有潜力。
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