One-Step Templating–Activation Strategy toward N-Doped Ordered Mesoporous Carbon Materials with Ultrahigh Microporosity for Efficient Gas Adsorption

Templating methods are widely used for synthesizing ordered mesoporous carbon materials (OMCs), but they lack the capability to control micropores, leading to low microporosity. In this work, a one-step templating-activation strategy combining hard templating and <i>in situ</i> activation in a single process is proposed for the synthesis of N-doped OMCs (NOMCs) with ultrahigh microporosity. The neutralization of histidine (His) and KOH forms a salt with a molecularly dispersed K species. During pyrolysis, the formed carbon is uniformly activated <i>in situ</i>, generating micropore-rich carbon walls. Removal of the template and K species results in NOMCs having not only ordered mesopores but also ultrahigh micropore surface areas up to 1493 m² g^-1, a record-high value among directly templated OMCs. The KOH/His molar ratio and pyrolysis temperature are critical to optimize the synthesis, and their influences on the properties of the resulting NOMCs are elucidated. The obtained materials possess N contents of 4.5-22.2 wt % depending on the pyrolysis temperature. The micropore-rich NOMCs exhibit high CO₂ adsorption performance, superior to the counterparts with either low microporosity or low mesoporosity. The typical material delivers a capacity of 7.6 mmol g^-1, a CO₂/N₂ selectivity of 53.2 at 1 bar, fast kinetics, and easy regeneration. The CO₂ capacity can be well-correlated to the microporosity, whereas the CO₂/N₂ selectivity is determined by microporosity and N species and influenced by mesoporosity. The micropore-rich NOMCs hold potential for uptake of various gases.