5-HMF-driven microporous N, O-dual doped carbon materials based on chitosan for syngas purification and CO₂ capture

Biomass-derived carbohydrates, as abundant and renewable feedstocks, hold great promise for producing porous carbon materials (PCMs) applicable in CO₂ capture and syngas purification. This study presents a novel strategy for synthesizing N, O-dual doped carbon (NOC) materials through co-pyrolysis using 5-hydroxymethylfurfural (5-HMF) and chitosan (CTS) as precursors, wherein 5-HMF acts as a structural modulator. Combining experimental characterization with density functional theory (DFT) calculations, this work systematically investigated the synergistic mechanism between functional group evolution and carbon framework construction during co-pyrolysis, and elucidated the influence of N, O doping configurations on CO₂ adsorption selectivity. The results indicate that the incorporation of 5-HMF promotes a three-step reaction pathway introducing N, O-containing functional groups such as imine group (C=N) and carbonyl (C=O). The NOC prepared at 800 °C exhibited a CO₂/H₂ selectivity of 43.4 and a CO₂/(CO + H₂) multicomponent selectivity of 24.4 in a continuous flow (CO₂/CO/H₂, 25 °C, 1 bar). Theoretical calculations further revealed that the synergistic coupling of pyridinic N and carbonyl groups on the carbon surface significantly enhances surface polarity and Lewis basicity, thereby strengthening the selective adsorption of polar CO₂ molecules via Lewis acid-base interactions and electrostatic induction.