Revealing the intrinsic electronic-level principle driving metal-support interaction trends of single-atom Ru with oxides through cooperative orbital coupling

Abstract Supports dominate chemical states and catalytic performances of single-atom catalysts (SACs); however, electronic-scale physicochemical principles intrinsically driving SAC-support interactions and their structure-function relationships are still not coherently clarified nor unified yet. Using atomically-supported Ru on rutile-type oxides MO2 (TiO2, SnO2, and MnO2) for CO adsorption and oxidation as model systems, here we explore the interaction trends and electronic-level origins of SAC-support interactions. Our results show that the reactivity of surface oxygen atoms overall controls the strengths of Ru1-MO2 binding and CO-Ru1 adsorption, and catalytic activity of CO oxidation. Through combining experimental probing and theoretical calculations, we reveal that these interaction trends can be coherently unified by an electronic-level interaction mode through competitive orbital coupling in CO-Ru1-O5-MO2 systems, in which neighboring bonds are competitive while non-neighboring bonds are cooperative in coupling strength. The interaction mode of orbitals provides new insights for understanding SAC-support interactions and rational design of SACs.