(399b) Hydrogen-Based Characterization of Nanoporous Carbons

Nanoporous materials play a critical role in advancing energy storage, gas separation, and
catalysis technologies. While traditional characterization methods employ nitrogen, argon, or
carbon dioxide adsorbates, each presents limitations when analyzing small micropores and
surface heterogeneities. Hydrogen, though underutilized as a characterization medium, offers
several compelling advantages: its smaller kinetic diameter enables access to ultramicropores
inaccessible to larger molecules, its quantum behavior provides additional information about
specific adsorption site interactions, and its supercritical properties at experimental temperatures
limit condensation effects that complicate analysis with other adsorbates.

Our research employs a quantum-corrected density functional theory (DFT) approach to generate
theoretical kernels of hydrogen and deuterium isotherms, accounting for isotope-specific
quantum effects that significantly influence adsorption behavior in highly confined spaces. By
mapping these theoretical isotherms to experimental adsorption data from several nanoporous
carbon materials, we calculate pore size distributions (PSDs) that reveal previously undetected
structural features. Comparative analysis with nitrogen-based non-local DFT (NLDFT) results
demonstrates that hydrogen-based characterization offers superior resolution for micropores and
more accurate assessment of pore geometry and surface energetics. These findings establish
hydrogen adsorption as a valuable complementary technique for comprehensive characterization
of nanoporous materials, particularly for applications demanding precise engineering of pore
structures at the sub-nanometer scale.