(497a) Beyond the Trade-Off between Pore Size and Pore Density in Single-Layer Graphene: From Atomic Simulation to Large-Scale Membranes

Industrial application of Å-scale pores into single-layer graphene for gas separation has been inherently challenging due to restricted understanding of both pore formation at atomic-scale and gas-phase transport in confined pores. Pore generation via oxidation route has led to Å-scale pore incorporation into graphene lattice. Nevertheless, for enhancing pore incorporation resolution, a fine control over pore evolution from the pore precursor (also called oxygen cluster) is highly attractive. Driven by the latter, we introduce a novel photonic gasification method of oxygen clusters to form gas sieving pores. First, we demonstrate that oxygen clusters grow into a core/shell structure formed by an ether core, surrounded epoxy group in a bid to minimize the core lattice strain. We then selectively gasified the core of the cluster at room temperature, using 3.2 eV light, leading to pore formation with enhanced control comparing to thermal gasification. This can be explained by the suppression of cluster coalescence induced by epoxy diffusion. Using O₃ oxidation temperature as a leverage, we demonstrate the feasibility of maintaining a narrow pore size distribution, independently of pore density. Such results enabled us to simultaneously increase gas permeance and gas pair selectivity, against a common tradeoff and long-lasting challenge in the field. Ultrahigh H₂ permeance of 12000 GPU alongside very attractive H₂/N₂ selectivity of 50 was achieved. Relying on HRTEM imaging, XPS and DFT, we could define realistic pores for molecular dynamics. So far, literature only considered rigid graphene pores with a static pore size which fails to capture permeation behaviour. Using molecular dynamics, we demonstrate that semiquinone groups decorating pores formed by photonic gasification of oxygen cluster, flex in and out of graphene plane, altering molecular transport. Allying size-sieving and competitive sorption, simulations revealed remarkable CO₂/O₂ mixture selectivity up to 59.4. Inspired by the rich interaction between CO₂ and oxygen-decorated pores, we demonstrated that photonic gasification can also be scaled up on centimetre-scale for CO₂ capture with CO₂ permeance of 1800 GPU alongside attractive CO₂/N₂ selectivity about 18.

Overall, this work will inspire research about cluster chemistry for advancing precision and scalability of pore incorporation at the angstrom-scale in single-layer graphene while paving the way for a comprehensive understanding of gas transport through single digit graphene pores.