Progress in MOF-based catalyst design and reaction mechanisms for CO₂ hydrogenation to methanol

Against the backdrop of escalating global climate change and energy crises, the resource utilization of carbon dioxide (CO2), a major greenhouse gas, has become a crucial pathway for achieving carbon peaking and carbon neutrality goals. The hydrogenation of CO2 to methanol not only enables carbon sequestration and recycling, but also provides a route to produce high value-added fuels and basic chemical feedstocks, holding significant environmental and economic potential. However, this conversion process is thermodynamically and kinetically limited, and traditional catalyst systems (e.g., Cu/ZnO/Al2O3) exhibit inadequate activity, selectivity, and stability under mild conditions. Therefore, the development of novel high-performance catalysts with precisely tunable structures and functionalities is imperative. Metal-organic frameworks (MOFs), as crystalline porous materials with high surface area, tunable pore structures, and diverse metal-ligand compositions, have the great potential in CO2 hydrogenation catalysis. Their structural design flexibility allows for the construction of well-dispersed active sites, tailored electronic environments, and enhanced metal-support interactions. This review systematically summarizes the recent advances in MOF-based and MOF-derived catalysts for CO2 hydrogenation to methanol, focusing on four design strategies: (1) spatial confinement and in situ construction, (2) defect engineering and ion-exchange, (3) bimetallic synergy and hybrid structure design, and (4) MOF-derived nanomaterial synthesis. These approaches significantly improve CO2 conversion and methanol selectivity by optimizing metal dispersion, interfacial structures, and reaction pathways. The reaction mechanism is further explored by focusing on the three main reaction pathways: the formate pathway (HCOO*), the RWGS (Reverse Water Gas Shift reaction) + CO* hydrogenation pathway, and the trans-COOH pathway. In situ spectroscopic studies and density functional theory (DFT) calculations elucidate the formation and transformation of key intermediates, as well as the roles of active sites, metal-support interfaces, oxygen vacancies, and promoters. Additionally, representative catalytic performance data for MOF-based systems are compiled and compared, demonstrating their advantages over traditional catalysts in terms of CO2 conversion, methanol selectivity, and space-time yield. Future perspectives for MOF-based CO2 hydrogenation catalysts will prioritize two main directions: structural design and mechanistic understanding. The precise construction of active sites through multi-metallic synergy, defect engineering, and interfacial electronic modulation should be made to enhance catalyst selectivity and stability. In addition, advanced in situ characterization techniques combined with theoretical modeling are essential to unravel the detailed reaction mechanisms and intermediate behaviors, thereby guiding rational catalyst design. Moreover, to enable industrial application, challenges related to thermal/hydrothermal stability, catalyst recyclability, and cost-effective large-scale synthesis must be addressed. The development of green, scalable preparation methods and the integration of MOF catalysts into practical reaction systems (e.g., flow reactors) will be crucial for bridging the gap between laboratory research and commercial deployment. Ultimately, multi-scale structure-performance optimization and catalytic system integration will be vital for accelerating the industrialization of MOF-based CO2-to-methanol technologies.