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 CO 2 and CH 4 . 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 (H 2 : 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.