The Significance of the 'Insignificant': Non-covalent Interactions in CO Reduction Reactions with 3C-TM (TM=Sc-Zn) Single-Atom Catalysts.

With energy shortages and excessive CO emissions driving climate change, converting CO into high-value-added products offers a promising solution for carbon recycling. We investigate CO reduction reactions (CORR) catalyzed by 10 single-atom catalysts (SACs), incorporating weak non-covalent interactions, specifically lone pair-π and H-π interactions. The SACs, consisting of transition metals coordinated by three carbon atoms in a defective graphene substrate (3C-TM, TM=Sc-Zn), leverage these interactions to influence the energy fluctuations of intermediates and the limiting potentials of CORR, without altering the overall reaction pathway. Our findings show that SACs based on early transition metals (Sc, Ti, V, Cr) can serve as catalysts for C products, including HCOOH, HCHO, CHOH, and CH, while those based on Fe and Co are suitable for CO formation. Driving force analysis helps bridge theoretical results with experimental observations and propose a modified approach for assessing hydrogen evolution reactions (HER) competition. SACs based on Ni and Cu exhibit moderate HER tolerance, while early transition metals excel in selective CO reduction. We also identify a linear scaling relationship between the free energies of *COOH and *CO. This study offers valuable insights for future experimental studies and large-scale computational screenings.