Metal-organic framework-based single-atom electro-/photocatalysts: Synthesis, energy applications, and opportunities

Single-atom catalysts (SACs) have gained substantial attention because of their exceptional catalytic properties. However, the high surface energy limits their synthesis, thus creating significant challenges for further development. In the last few years, metal–organic frameworks (MOFs) have received significant consideration as ideal candidates for synthesizing SACs due to their tailorable chemistry, tunable morphologies, high porosity, and chemical/thermal stability. From this perspective, this review thoroughly summarizes the previously reported methods and possible future approaches for constructing MOF-based (MOF-derived-supported and MOF-supported) SACs. Then, MOF-based SAC's identification techniques are briefly assessed to understand their coordination environments, local electronic structures, spatial distributions, and catalytic/electrochemical reaction mechanisms. This review systematically highlights several photocatalytic and electrocatalytic applications of MOF-based SACs for energy conversion and storage, including hydrogen evolution reactions, oxygen evolution reactions, O₂/CO₂/N₂ reduction reactions, fuel cells, and rechargeable batteries. Some light is also shed on the future development of this highly exciting field by highlighting the advantages and limitations of MOF-based SACs.