Engineering heterostaple in atomically precise palladium cluster for efficient hydrogen peroxide electrosynthesis

The deliberate construction of well-defined heterostaples within atomically precise metal clusters offers a powerful route to heterometallic systems with unconventional functionalities and promising catalytic potential. However, realizing such precise interface engineering in palladium-based clusters remains highly challenging. Here, we report the first successful synthesis of well-defined Pd₅Au₂ and Pd₅Cu₂ architectures featuring heterometallic interfaces by customizing dual-atom site (Au-Au or Cu-Cu) in atomically precise palladium cluster. Their structures were unambiguously determined by single crystal X-ray diffraction (SCXRD) and electrospray ionization mass spectrometry (ESI-MS). Both heterometallic clusters share a similar architecture, comprising a slightly folded Pd₅S hexatomic ring encapsulating a central antimony atom from PhSb^2- ligand, a M₂S₃ (M=Au or Cu) staple and four bridging thiolate ligands. Incorporation of the Au-Au or Cu-Cu subunit modulates the geometric and electronic environments of the palladium core to varying extents, leading to markedly distinct two-electron oxygen reduction reaction performances. Notably, Pd₅Au₂ achieves a nearly 100% H₂O₂ Faradaic efficiency at 25 mA cm^-2 and an exceptional H₂O₂ production rate of 1366.4 mmol g_cat^-1 h^-1 at 125 mA cm^-2. Its efficacy was further demonstrated in practical Fenton-type pollutant degradation. Density functional theory (DFT) calculations, corroborated by operando infrared spectroscopy, reveal that the introduction of an Au-Au dual-atom site induces an electronic redistribution that weakens the *OOH adsorption, thereby facilitating its hydrogenation step. This study represents the first realization of atomically precise palladium-based clusters equipped with heterometallic interfaces, providing new mechanistic insights and design principles for cluster-based catalysts in small-molecule energy conversion.