Interfacial Ru–C Coupling Harnesses Photoexcited Hot Electrons to Sustain Oxygen Cycling in Photothermal Methane Dry Reforming

ABSTRACT Methane dry reforming (DRM) remains challenged by the difficulty of simultaneously achieving high activity and long‐term stability under moderate‐temperature operation. Here we report sub‐2 nm Ru clusters anchored on chemically stable multi‐walled carbon nanotubes (Ru/MWCNTs) as a non‐oxide photothermal platform for efficient and durable DRM below 600 °C. Strong Ru–C π–d coupling delocalizes interfacial electrons and stabilizes metallic Ru, enabling broadband generation and interfacial utilization of photoexcited hot electrons under illumination. The resulting interface selectively activates CO 2 to generate highly labile Ru–O* species and sustains a fast, fully reversible Ru 0 /Ru–O cycle without relying on lattice oxygen from an oxygen‐carrier support. Rapid interfacial oxygen turnover promotes an oxygen‐assisted CH 3 O* pathway, delivering a turnover frequency of 25 s −1 . Consequently, Ru/MWCNTs achieves CO and H 2 formation rates of 632 and 526 mol g Ru −1 h −1 , respectively, a light‐to‐fuel efficiency of 25.4%, stable operation for 120 h, and robust activity across a wide CH 4 /CO 2 feed‐ratio window (0.43–2.33). Isothermal monochromatic irradiation together with operando, electronic, and kinetic analyses identify Ru–C interfacial coupling, rather than metallicity alone, as the key origin of the photothermal enhancement.