Supported Metal Single‐Atom Thermocatalysts for the Activation of Small Molecules

The activation and selective valorization of small molecules such as H 2 O, CH 4 , CO x , N 2 are expected to play a central role in the shift needed by the chemical industry basis, to solve sustainability issues associated with the current use of crude oil as the universal feedstock. However, activating these generally recalcitrant and unreactive molecules, and selectively steering their conversion pathways face important kinetic hurdles. With emphasis on conversion processes driven by temperature, i.e. lacking additional stimuli such as a voltage bias or light irradiation, for the conversion of C 1 molecules (CH 4 , CO 2 , and CO), this chapter discusses the benefits and drawbacks anticipated for monoatomic metal active sites in oxide-supported single-atom catalysts (SACs) compared to their polynuclear metal aggregate counterparts. The fundamentals underlying the activation of these simple molecules are succinctly discussed. Then, achievements attained in their selective conversion with supported, atomically dispersed metal catalysts are reviewed. Success cases, which have already reached industrial interest, are highlighted. In other cases, major challenges remaining in the way toward performances of technical interest are identified. The chapter additionally underscores how the dynamic fluxionality observed for those monoatomic sites on SACs calls for the development and application of high-sensitivity operando physicochemical methods, to track their structure prior to, during, and after catalytic action, to draw solid conclusions on the structure of the active metal species responsible for the catalytic performances observed macroscopically.