Pore Geometry and Nitrogen Doping Regulate Carbon-Source Transport Through Carbon Nanocage Shells for CO₂...

Carbon nanocages provide confined reaction environments for CO₂ reduction reaction (CO₂RR), but carbon sources must first cross their microporous graphitic shells to reach encapsulated catalytic sites. Here, molecular dynamics simulations were used to elucidate carbon-source transport through through-layer pores (TLPs), representing the edge-rich vertical micropores formed across stacked graphene layers in carbon nanocages. We examined the effects of pore diameter, N-doping, and pore depth on the transport of CO₂RR-relevant carbon species. Among the investigated structures, a 12.1 Å N-doped TLP achieved the highest area-normalized cross-pore transport ratio of 1.296 × 10^-2 Å^-2. N-doping preferentially enhanced neutral CO₂ transport, while producing only limited improvements for bicarbonate and carbonate ions. This selectivity originates from strong CO₂ interactions with N-containing pore-edge sites, which establish a CO₂-enriched interfacial region and promote adsorption-assisted capture-transfer without persistent molecular trapping. N-doping reduces both resistance contributions, leading to an approximately 30.4% decrease in pore-mouth resistance and ~45% reduction in pore-interior resistance at pore depths of 17.0 Å. These results identify short, appropriately sized, and N-functionalized through-layer micropores as favorable architectures for delivering CO₂ to confined catalysts, providing molecular design principles for carbon-nanocage nanoreactors for CO₂RR.