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

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 Ru^δ+-O_v-Ce³⁺ interfacial sites preferentially dissociate CH₄ into CH₃ ^* species that are further oxidized to CH₃O^* via a low-barrier, lattice oxygen-mediated pathway, while Ni^δ+-O_v-Ce³⁺ sites readily activate CO₂ and replenish O_lattice. This oxidative pathway effectively suppresses CH_x deep dehydrogenation and, coupled with Ni-driven CO₂ activation, establishes a self-sustaining O_lattice/O_v 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.