Resolving the Activity-Stability Trade-Off in Methane Dry Reforming via Ru-Preferential CH4 Activation on Isolated Ni-Ru Dual Sites.

Dry reforming of methane, the endothermic co-conversion of CH4 and CO2 into syngas (H2/CO), is typically limited by low-temperature activity and carbon-induced deactivation at high temperatures. Here, a geometrically isolated dual-site architecture is established by co-anchoring Ni and Ru atomic sites on defect-rich CeO2. The optimized 1NiRu/CeO2 catalyst achieves CH4/CO2 conversions of 21.46%/24.10% and a H2/CO ratio of 0.91 at 500°C, and approaches equilibrium (86.77%/92.78%) at 750°C. 1NiRu/CeO2 demonstrates outstanding stability over 150 h, with negligible carbon deposition compared to 1Ru/CeO2. Operando spectroscopy and theoretical calculations reveal preferential CH4 activation at Ru sites in the isolated Ni-Ru dual-site structure. The Ruδ+-Ov-Ce3+ interfacial sites preferentially dissociate CH4 into CH3 * species that are further oxidized to CH3O* via a low-barrier, lattice oxygen-mediated pathway, while Niδ+-Ov-Ce3+ sites readily activate CO2 and replenish Olattice. This oxidative pathway effectively suppresses CHx deep dehydrogenation and, coupled with Ni-driven CO2 activation, establishes a self-sustaining Olattice/Ov redox cycle. This synergistic cycle enables a site-selective division of labour for CH4/CO2 activation, thereby maintaining coke-resistant activity across 400°C-750°C. This work establishes a generalizable strategy for isolated dual-site catalyst design, where Ru-preferential CH4 activation and vacancy-governed interfacial cooperation orchestrate low-temperature activity, stability, and coke resistance, enabling efficient and durable CH4/CO2 valorization via dry reforming.