Unveiling Long-Range Wavelike Alternately Competitive and Cooperative Bond Coupling Modes in Single-Atom Catalysis

Supports can critically influence or even dominate the chemical state, adsorption property, and catalytic performance of single-atom catalysts (SACs), but the fundamental physicochemical principles driving adsorbate–M₁–ligand–support bond interactions have not been fully understood yet. Here, we reveal the orbital–level interaction modes underlying the long-range bond couplings in SACs by using single-atom Ru (Ru₁) supported on rutile-type oxides (TiO₂, SnO₂, and MnO₂) in CO adsorption and oxidation as a model system. Our results show that Ru₁–support binding strength and catalytic activity for CO oxidation increase in the following order: Ru₁/TiO₂ < Ru₁/SnO₂ < Ru₁/MnO₂, while CO–Ru₁ adsorption strength oppositely decreases as Ru₁/TiO₂ > Ru₁/SnO₂ > Ru₁/MnO₂. These interaction trends are overall controlled by the reactivity of surface lattice oxygen atoms (O_sl) on supports. We further discover an alternating competitive and cooperative bond coupling mode in the heteroatomic chains of adsorbate–M₁–ligand–support systems, in which the strengths of adjacent bonds competitively suppress, while alternating bonds cooperatively enhance. This wavelike bond coupling mode provides a new point to understand support effects on SAC–support interactions and structure–function relationships in SACs.