Tuning Reaction Pathways by Controlling Atomic Assembly on Oxide Clusters

ABSTRACT Precisely controlling the assembly of atomic sites on oxide clusters (< 1 nm) represents an expanded yet challenging strategy for tuning catalytic performance. Here, we construct two well‐defined model catalysts, single‐atomic Pt on CuO x clusters (Pt 1 ‐CuO x /CN) and triple‐atomic Pt on CuO x clusters (Pt 3 ‐CuO x /CN), and employ methanol oxidation reaction (MOR) as a probe to unravel the role of atomic assembly in governing catalytic mechanisms. Pt 1 ‐CuO x /CN enables a CO‐free pathway, achieving an ultrahigh formate selectivity of 80%–99% over a wide potential window (0.6–1.0 V vs. RHE). In contrast, Pt 3 ‐CuO x /CN follows a hybrid pathway involving both formate and CO routes, delivering significantly higher mass activity than that of Pt 1 ‐CuO x /CN and the commercial Pt/C, alongside high resistance to CO poisoning. Isolated Pt sites in Pt 1 ‐CuO x /CN impose a prohibitively uphill free‐energy change for the key *COH intermediate (2.15 eV), effectively suppressing CO generation. Conversely, triangular Pt sites in Pt 3 ‐CuO x /CN form a robust electronic localization center via deep 5d orbital hybridization, facilitating d→π* electron back‐donation and stabilizing *COH adsorption in a triple hollow‐site configuration, lowering the limiting free‐energy requirement for the CO pathway. This work reveals the role of atomic‐scale assembly on oxide clusters in dictating catalytic mechanism and performance, opening new avenues for precise design of advanced electrocatalysts.