Atomically Dispersed Iron: The Next Frontier in Green Catalysis

Iron has played a pivotal role in catalytic transformations for years, and its versatility continues to drive advances in modern sustainable chemistry. In recent years, iron-based single-atom catalysts (Fe-SACs) have emerged as promising alternatives to conventional heterogeneous catalysts, offering atomically dispersed active sites that combine the stability of heterogeneous systems with the selectivity of homogeneous catalysis. This review provides a comprehensive overview of Fe-SACs, with a particular focus on their synthesis, structural engineering, and stabilization on a wide range of supports, including carbon materials, metal–organic frameworks, metal oxides, and layered substrates. Special emphasis is placed on the interfacial chemistry, coordination environment, and electronic structure of isolated Fe sites, which critically influence catalytic performance. In addition, the review systematically explores the diverse environmental applications of Fe-SACs, including pollutant degradation, CO₂ conversion, Fenton-like reactions, oxygen reduction reactions, and green organic transformations. The role of theoretical calculations, particularly density functional theory, is highlighted in understanding active site behavior and reaction mechanisms, while emerging artificial intelligence and machine-learning approaches are discussed for their potential to accelerate catalyst design and optimization. Finally, current challenges, scalability considerations, and future research directions are outlined, providing a forward-looking perspective for the development of next-generation Fe-SACs in sustainable catalytic science.