Mechanochemical\nSynthesis of High-Entropy MOF-74 with\nMultiple Active Sites for CO<sub>2</sub> Adsorption and Synergistic\nConversion

Compared with monometallic metal–organic frameworks\n(MOFs),\nthe synergistic effect of multiple metals significantly enhances the\ncatalytic performance of the CO<sub>2</sub> cycloesterification reaction,\nleading to improved CO<sub>2</sub> adsorption and catalytic conversion\ncapabilities. To investigate this concept, a high-entropy MOF-74 (HE-MOF-74)\nwith a uniform distribution of five distinct metal ions (Zn<sup>2+</sup>, Mg<sup>2+</sup>, Ni<sup>2+</sup>, Co<sup>2+</sup>, and Cu<sup>2+</sup>) was successfully synthesized using a straightforward mechanical\nball milling technique and comprehensively characterized (including\nstructural, morphological, and physicochemical properties). The results\nreveal that HE-MOF-74 exhibits significantly increased specific surface\narea and CO<sub>2</sub> adsorption capacity compared with those of\nmonometallic MOF-74. The presence of multiple unsaturated metal centers\nas Lewis acid sites, oxygen atoms linking the metals, and ligand-based\nhydroxyl groups serving as base sites enable efficient immobilization\nof CO<sub>2</sub> into cyclic carbonate. This study introduces a novel\nsynthetic approach for the green and efficient production of HE-MOF-74\nand proposes a new application for CO<sub>2</sub> utilization.