Periodate oxidation and schiff-base amination of wood-derived cellulose: Engineering a CO₂-active macromolecular...

Cellulose, the most abundant natural biomacromolecule, provides a hierarchically porous polysaccharide framework and chemically addressable hydroxyl groups for constructing functional porous materials. However, systematic comparisons across structurally diverse MOF families on a chemically uniform cellulose-derived scaffold are lacking, and how scaffold chemistry and framework topology cooperate to govern CO₂ capture has not been directly addressed. Herein, wood-derived cellulose was modified through NaIO₄ cleavage of C2-C3 vicinal diols followed by Schiff-base amination with ethylenediamine, yielding a dialdehyde-aminated wood sponge (DAEW) that retained the aligned porosity of native wood while introducing densely anchored amine sites. Five structurally distinct MOFs, MIL-53(Al), ZIF-8, MOF-199, Mg-MOF-74, and UiO-66, were grown in situ on DAEW. SEM, XRD, FTIR, XPS, and N₂ sorption analyses confirmed that the amine-rich surface promoted uniform MOF deposition, enabled robust anchoring, and preserved framework crystallinity across all five systems. Adsorption measurements combined with DFT calculations revealed that single-site binding strength is not the sole determinant of macroscopic CO₂ capture: although UiO-66/DAEW showed the strongest single-site CO₂ binding and the highest isosteric heat of adsorption, MIL-53(Al)/DAEW exhibited the best overall performance, with a CO₂ uptake of 2.89 mmol·g^-1 at 273 K and 1 bar and an IAST CO₂/N₂ selectivity of 112.84 for a 15:85 mixture. This behavior arose from framework breathing, CO₂-size-matched pore confinement, size-selective N₂ exclusion, and amine-mediated CO₂ activation. These findings establish modified cellulose as a viable platform for integrating diverse MOF families and underscore the dominant role of pore-scaffold cooperativity over local binding strength in governing CO₂ capture performance.