Cellulose-supported Mg/Ni-MOF-74 with tunable bimetallic sites for efficient CO2 adsorption

Cellulose directs Mg/Ni-MOF-74 growth on fiber surfaces. • Tuning Mg/Ni ratio optimizes pore structure and open metal site characteristics. • MNC-1 exhibits high CO 2 capacity and CO 2 /N 2 selectivity (>200). • Hierarchical porosity facilitates both CO 2 confinement and gas mass transfer. • Low isosteric heat of adsorption promotes easy regeneration. To overcome the poor dispersibility and limited gas mass transfer of MOF powders, a series of Mg/Ni-MOF-74/cellulose composites (MNC-x) were fabricated via cellulose interface directed in situ growth. The effects of the Mg/Ni ratio on the material structure and CO 2 /N 2 adsorption performance were investigated. Results showed that the introduction of Ni altered the local environment and crystal size, regulating the pore structure and adsorption sites of the MNC-x series materials. The optimal sample (MNC-1) achieved a static CO 2 adsorption capacity of 2.67 mmol·g −1 at 298 K and exhibiting superior cycling performance. IAST theoretical calculations indicated that MNC-1 possessed high CO 2 /N 2 selectivity, with an initial isosteric heat of adsorption of only 34.51 kJ·mol −1 , indicating that physical adsorption was predominant. Combined with DFT analysis, the excellent CO 2 adsorption performance of MNC-1 was mainly attributed to the interaction between the open metal sites of Mg/Ni and CO 2 , as well as the hierarchical pore structure formed by the microporous adsorption sites and mesoporous mass transfer channels. This study provides a feasible strategy for designing cellulose-supported, processable bimetallic MOF adsorbents for CO 2 adsorption. Download: Download high-res image (269KB) Download: Download full-size image