Directed Construction of Hierarchical Porous Carbon With Ultrahigh Surface Area for High-Density Methane Storage at Room Temperature.

Abstract

Efficient methane storage remains a fundamental challenge for the deployment of adsorbed natural gas technologies, owing to the long-standing difficulty of simultaneously achieving high gravimetric and volumetric storage capacities. Here, we report a directed materials-design strategy that links molecular precursor topology to defect evolution and hierarchical pore formation in porous carbons. By exploiting the distinct pyrolytic topologies of cyanide-based ionic liquid anions, we program defect densities in carbon frameworks and guide the development of micro-mesoporous architectures through chemical activation. This approach yields a hierarchical porous carbon with an ultrahigh Brunauer-Emmett-Teller area of 5011 m² g^-1 and a physically accessible pore volume of 2.48 cm³ g^-1 as determined by skeletal density and tap density measurements, enabling exceptional methane storage performance at room temperature. At 298 K and 100 bar, this material achieves a gravimetric adsorption capacity of 0.48 g g^-1. Accordingly, its volumetric adsorption capacity reaches 228 cm³ (Standard temperture and pressure, STP) cm^-3 at a tap density of 0.337 g cm^-3 and 275 cm³ (STP) cm^-3 at a compacted density of 0.407 g cm^-3. Beyond methane storage, our findings establish a generalizable paradigm for constructing high-performance porous carbons by topologically programming defects and pore hierarchies, with implications for energy storage and gas adsorption technologies.