(566c) Mechanistic Investigation of Semiquinone-Functionalized ?-Scale Graphene Nanopores for Carbon Capture Applications

Given the escalating challenges posed by climate change, the development of advanced carbon capture technologies has become crucial for mitigating greenhouse gas emissions. Among the plethora of innovative materials under exploration, graphene-based membranes stand out as exceptional candidates owing to their unparalleled structural and functional versatility. In particular, the semiquinone (C=O) functionalized Å-scale pores¹, incorporated by the oxidation of graphene, has shown significant promise for carbon capture applications. However, the complete potential of these pores remains elusive owing to the lack of dedicated mechanistic investigations.

In this study, we utilize molecular dynamics simulations to reveal that the semiquinone functional groups exhibit remarkable molecular-interaction-dependent dynamic behavior, resulting in variations in pore-limiting diameters comparable to the size differences among the CO₂, O₂, and N₂ gas molecules. Small pores are found to undergo dynamic transitions between the open and closed states, rendering traditionally impermeable pores into selective ones for CO₂ transport. This leads to exceptional room temperature selectivities of the CO₂/O₂ and CO₂/N₂ mixtures - approaching 300 and 400, respectively. Interestingly, the strong molecular interactions tend to eliminate effusive transport, enabling selective translocation of CO₂ molecules even through large pores which are conventionally regarded as non-selective.

Furthermore, the transition-state theory, typically utilized for qualitative estimates of gas translocation flux, has been improvised to give quantitative and robust predictions for CO₂, O₂ and N₂ gas molecules translocating through the graphene nanopores terminated with semiquinone functional groups. These calculations, corroborated by molecular dynamics simulations, highlight the immense potential of porous graphene to surpass the performance of existing membrane technologies for carbon capture. Moreover, this approach circumvents the need for resource-intensive simulations and resolves statistical challenges associated with rare translocation events².

The findings of this work provide valuable insights into the design of advanced graphene membranes, paving the way for innovative advancements in the carbon capture landscape and demonstrating a pathway toward addressing global climate challenges.

References:

(1) Bondaz, L.; Ronghe, A.; Li, S.; Čerņevičs, K.; Hao, J.; Yazyev, O. V.; Ayappa, K. G.; Agrawal, K. V. Selective Photonic Gasification of Strained Oxygen Clusters on Graphene for Tuning Pore Size in the Å Regime. Jacs Au 2023, 3 (10), 2844–2854.

(2) Bondaz, L.; Ronghe, A.; Ayappa, K. G.; Agrawal, K. V. Gated CO2 Permeation across Dynamic Graphene Pores. Chemistry January 22, 2025. https://doi.org/10.26434/chemrxiv-2025-1pjgf.