The recent interest on the heterogeneous single-atom catalysts (SACs) were composed of atomically dispersed active metal cen ters in catalyst research field, because of the increased atom utilization and unique catalytic properties of such materials, which differ greatly from those of conventional nano or subnano counter parts. In this case, the fabrication of SACs are challenging, especially in the case of noble metal based catalysts and many researches are ongoing in this field for the development of improved catalysts. Many chall enges have faced for the hybridization of controlling of single atoms in suitable host materials, but it has also equally opened with unique opportunities for catalyst design. SACs with atomically dispersed active metal centers on supports represent an intermediary between heterogeneous and homogeneous catalysis. Therefore, understanding the homogeneous catalysis prototype creates a great opportunity for designing SACs and developing related applications....