Synergy Between Photon-to-Phonon Pathway and Active Lattice Oxygen Enables Efficient and Stable Syngas Synthesis

Light-driven dry reforming of methane (DRM) offers a promising route for syngas synthesis while simultaneously mitigating greenhouse gas emissions of CO₂ and CH₄. However, the attractive mild-temperature operating window imposes kinetic constraints on C─H/C═O activation and promotes thermodynamic tendencies for coke formation, resulting in limited efficiency and stability. Herein, manganese oxide (MnO_x) is employed as a multifunctional support to integrate the classic Rh catalytic center, establishing a new benchmark photothermo catalyst for DRM. The system achieves record-high syngas production rates (H₂: 948 mmol g^-1 h^-1; CO: 992 mmol g^-1 h^-1) without external heating, alongside exceptional long-term stability (∼500 h). These production rates and stability also surpass conventional thermocatalysts in similar temperature ranges, with stability exceeding most thermocatalysts by an order of magnitude. Under a separate low-conversion, high-gas hourly space velocity (GHSV) protocol, a light-to-chemical efficiency (29.5%) can also be reached. MnO_x functions as a broadband light harvester, generating a localized thermal field at the micrometre-scale via an efficient photon-to-phonon pathway to facilitate C─H bond activation on Rh. Concurrently, its active lattice oxygen enables a dynamic O_L-O_V cycle for timely removal of C* intermediates and C═O activation. This work underscores the critical role of support engineering in advancing light-driven DRM.