Single-atom catalysis: Bridging the homo- and heterogeneous catalysis

Single-atom catalysis, the catalysis by single-atom catalysts (SACs), has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field. SACs have the advantages of both homogeneous catalysts (isolated active sites) and heterogeneous catalysts (stable and easy to separate), and are thus predicted to be able to bridge the homo- and heterogeneous catalysis. This prediction was first experimentally demonstrated in 2016. In this mini-review, we summarize the few homogeneous catalysis progresses reported recently where SACs have exhibited promising application: a) Rh/ZnO and Rh/CoO SAC have been used successfully in hydroformylation of olefin of which the activity are comparable to the homogeneous Wilkinson's catalyst; b) a Pt/Al2O3 SAC has shown excellent performance in hydrosilylation reaction; and c) M-N-C SACs (M = Fe, Co etc.) have been applied in the activation of C–H bonds. All of these examples suggest that fabrication of suitable SACs could provide a new avenue for the heterogenization of homogeneous catalysts. These pioneering works shed new light on the recognition of single-atom catalysis in bridging the homo- and heterogeneous catalysis.