Bimetallic Hf-Based MOFs with Synergistic Metal Sites for CO ₂ Conversion to Cyclic Carbonates and <i>N</i> -formamides

The continuous rise in atmospheric CO 2 levels poses significant threats to global ecosystems and human health, underscoring the urgent need for efficient carbon capture and utilization technologies. Metal–organic frameworks (MOFs) have emerged as promising heterogeneous catalysts for converting CO 2 into value-added chemicals. In this work, we report the one-pot synthesis of three novel bimetallic MOFs (Hf-Cu-MOF, Hf-Co-MOF and Zr–Cu-MOF), constructed from hafnium-oxo (or zirconium-oxo) clusters and 4-pyridinecarboxylic acid ligands. These materials exhibit high structural stability and abundant Lewis acid sites. Among them, Hf-Cu-MOF demonstrated superior CO 2 adsorption capacity and catalytic performance in the cycloaddition of CO 2 with epoxides to form cyclic carbonates, achieving a conversion rate of 96.1%. Moreover, Hf-Cu-MOF also catalyzed the N -formylation of amines with CO 2 and phenylsilane under ambient conditions, affording near-quantitative conversion (98.7%). The outstanding performance is attributed to the synergistic effect of unsaturated metal centers (Hf 4+ and Cu ions) and O–H groups, which function as Lewis acid sites and Brønsted acid sites, along with the optimized pore confinement within the framework. Notably, a gram-scale synthesis of Hf-Cu-MOF was successfully achieved, demonstrating robust scalability and consistent performance. This study highlights the potential of Hf-based bimetallic MOFs as efficient and reusable catalysts for sustainable CO 2 conversion, presenting promising prospects for industrial application.