Hierarchically porous wood/CuBTC/GO composites for efficient and selective CO2 capture

Abstract

A composite adsorbent material for CO₂ capture was prepared using low-density, high-porosity balsa wood (BW) as the matrix, with the introduction of CuBTC and graphene oxide (GO). Characterization via scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy, and X-ray diffraction (XRD) confirmed the uniform synthesis of the octahedral CuBTC within the wood pores. The introduction of GO increased the loading of CuBTC by 28.3%, with the final loading reaching 46.7%. FTIR analysis revealed interfacial interactions—hydrogen bonding and Cu²⁺ coordination. Compared to pure CuBTC, the composite exhibited higher thermal stability (up to 500 K) and excellent water resistance, with minimal structural changes after 6 h of immersion. Its microporous surface area, pore volume, and average pore diameter reached 229 m²·g^-1, 0.12 cm³·g^-1 and 2.01 nm, respectively. Under conditions of 298 K and 1 bar, the CO₂ adsorption capacity reached 1.93 mmol·g^-1, and it exhibited excellent cycling stability. The average CO₂ adsorption heat was 32 kJ·mol^-1, indicating that the adsorption mechanism was primarily physical adsorption, i.e., wood acted as a high-speed channel for CO₂ transport, while the unsaturated copper sites exposed on CuBTC in the wood pores interacted electrostatically with the quadrupole moment of CO₂. Additionally, this composite material exhibited high CO₂/N₂ selectivity (up to 71), outperforming pure CuBTC, highlighting its potential for application in CO₂ capture. This study is valuable for the functionalization of wood.