Metal-Organic Frameworks as a Good Platform for the Fabrication of Single-Atom Catalysts

In summary, this Viewpoint has tried to provide an up-to-date overview of the significant advances in MOF-based SACs fabricated by using MOFs as supports or precursors. As described in this Viewpoint, we can clearly see the great potential of MOFs as a platform for creating a large number of MOF-based SACs with some charming structural and/or catalytic properties. However, despite the rapid progress that has been made in this field, there still remain some issues or challenges that should be addressed or considered in the future. For instance, although MOF-based SACs have shown good catalytic performances in some reactions under relatively mild conditions, unfortunately, their poor stability has been regarded as one of the major barriers limiting their widespread utilization in practical applications. Therefore, follow-up studies should develop more facile and powerful approaches to prove the stability of MOF-based SACs to advance their practical utilization. On the other hand, the metal loadings of the present MOF-based SACs should be further increased from a practical application perspective, especially for electrocatalytic applications, where a high density of active sites is usually necessary to promote the current density. However, the agglomeration of metal atoms to form nanoparticles is an inevitable issue when the metal loadings of MOF-based SACs are increased. The combination of theoretical modeling and simulations and the development of a new effective strategy may provide potential opportunities for producing MOF-based SACs with high metal loadings. Furthermore, the preparation of MOF-based SACs is still at the laboratory level so far, and thus developing scalable strategies is obviously a great challenge that must be faced in the future for real industrial applications. Therefore, tremendous efforts have to be made to generate feasible guiding principles and technical essentials for optimizing the fabrication strategies to achieve MOF-based SACs with the desired structural and catalytic properties that can be applied to large-scale industrial applications. With the aforementioned progress and unflagging endeavors in this field, we are confident that MOF-based SACs will have a very bright future. Copyright © 2020 American Chemical Society.