Synergistic Rh ₁ –Cu ₁ Dual‐Atom‐Site Enhancing Performance of Ethane Low‐Temperature Oxidation via Auto‐Selective Oxygen Source From O ₂ /H ₂ O

The low-temperature direct conversion of ethane is more appealing for the utilization of shale gas. Dual-atom catalysts have attracted considerable attention due to their unique cooperative effects. Herein, we report a porous organic polymer-supported Rh₁-Cu₁ dual-site catalyst (Rh₁-Cu₁@POPs-PPh₃) for the selective oxidation of ethane to ethanol, acetaldehyde, and acetic acid with auto-selective oxygen mechanism. The optimized Rh₁-Cu₁ centers deliver a productivity of ca. 250 mol mol_Rh ^-1 h^-1 based on Rh with 65% acetaldehyde selectivity at 423 K, representing a four-fold improvement over the single-Rh-site catalyst. Through isotopic labeling and in situ characterizations, we uncover an auto-selective oxygen source mechanism in which dehydrogenated species of ethane with different grades possess self-selectivity for the combined oxygen source. Oxygen species derived from O₂ activate ethane and subsequently couple with the ethyl fragment to produce ethanol. While OH radicals from H₂O dissociation react with ethyl intermediates from ethane dehydrogenation to yield acetaldehyde. Concurrently, oxygen species recombine with reactive hydrogen species to regenerate new H₂O, completing the catalytic oxidation cycle. The density functional theory (DFT) calculations reveal that the Rh-Cl-Cu configuration lowers the lowest unoccupied molecular orbital (LUMO) energy of Rh₁, thereby strengthening adsorbate-metal interactions, weakening the C─H bond, and facilitating its activation.