Multi-metal/ligand MOFs: Transformative materials for energy storage, photocatalysis, and sensor technologies

Metal-organic frameworks (MOFs) are a highly versatile class of materials that have attracted considerable attention because of their unique structural tunability and broad range of applications. The introduction of multiple metals and ligands into the MOF structures has emerged as an effective strategy to enhance their properties and expand their application range. Mixed-metal MOFs incorporate metals with varying oxidation states or coordination environments, thereby improving properties such as stability, porosity, and catalytic activity. Similarly, the mixed-ligand MOFs comprised of multiple organic linkers offer additional flexibility in modifying pore structures and functional properties. These hybrid frameworks have demonstrated significant potential in a variety of applications, including gas storage, separation, catalysis, sensing, and environmental remediation. This review classifies the most frequently utilized metals in MOFs and focuses on their roles in mixed-metal and mixed-ligand structures. It also discusses how incorporating different metals or ligands can improve the MOF key properties. Moreover, this review presents a comprehensive overview of the different synthesis techniques used in fabricating MOFs, ranging from solvothermal methods to innovative approaches such as microwave-assisted synthesis and electrochemical methods. The synergistic interactions between different metals are highlighted, showcasing the unique advantages of these combinations in enhancing MOF functionality. Finally, the applications of mixed-metal and mixed-ligand MOFs in energy storage, photocatalysis, and sensor technologies are discussed.