3D interconnected pore networks enable superior volumetric CO2 uptake in amine-functionalized nanoporous carbon for direct air capture

• ⁠⁠Fully 3D-interconnected nanoporous carbon enables efficient CO₂ diffusion and capture • ⁠⁠Amine-functionalized carbon pellets reach 1.6 mmol/cm 3 , over 3 × typical sorbents • ⁠Hierarchical pores ensure uniform amine dispersion and full site utilization • Nanoscale-engineered carbon ensures high strength and efficient porosity • ⁠⁠Demonstrates scalable route to compact, energy-efficient direct air capture systems Direct Air Capture (DAC) is a critical technology for mitigating atmospheric CO 2 concentrations, but current systems require substantial space and high energy input, largely due to the low volumetric CO 2 capture capacity of existing sorbents. A major limitation arises from the intrinsic trade-off in conventional mesoporous platforms, where increasing amine loading often compromises CO 2 diffusion efficiency, resulting in poor volumetric performance. In this report, we introduce a solid-state sorbent platform that overcomes this limitation by leveraging a fully interconnected three-dimensional (3D) pore network. The sorbent, composed of polyethyleneimine (PEI)-functionalized nanoporous amorphous carbon (NAC) millimeter-sized monoliths, features a hierarchically organized pore architecture with high volumetric pore density, enabling deep and uniform amine infiltration while maintaining unobstructed CO 2 diffusion pathways. This synergistic pore design yields a remarkable volumetric CO 2 uptake of ∼1.6 mmol/cm³ under pre-hydrated conditions—over threefold higher than that of the best-performing shaped sorbents reported to date. The NAC–PEI monoliths further exhibit cyclic stability, mechanical robustness, and negligible pressure drop, supporting their integration into compact and energy-efficient continuous DAC modules. These findings establish pore interconnectivity as a key design principle for next-generation solid sorbents, enabling space-efficient, high-performance carbon removal systems suitable for urban and distributed deployment.