Coupling Interfacial Charge Separation with Oxygen Vacancy Dynamics for Light-Driven Dry Reforming of Methane via 2D CeO ₂ Nanosheets

Light-driven dry reforming of methane (LDRM) provides a feasible route for converting methane (CH 4 ) and carbon dioxide (CO 2 ) into synthesis gas, yet most reported systems require ultraviolet light or a high photon flux, limiting their practical deployment. Here, we show that interfacial oxygen vacancy dynamics can be regulated under mild broadband irradiation through engineered metal–support electronic coupling. In this way, Rh nanoparticles (NPs) supported on two-dimensional CeO 2 nanosheets (NS) exhibit record-high Rh-specific activity under low-intensity broadband irradiation (1.20 W·cm –2, 200–800 nm) without external heating, delivering H 2 and CO production rates of 681 and 832 mmol·g Rh –1 ·h –1, respectively, together with the highest light-to-chemical energy conversion efficiency (LTCEE) reported for Rh-based LDRM catalysts under low-intensity irradiation (≤3.0 W·cm –2 ). In-situ characterizations, combined with density functional theory calculations, reveal a photochemical Mars–van Krevelen mechanism driven by interfacial charge separation. Photoexcited electrons transfer from CeO 2 -NS to Rh NPs across the Schottky junction, generating electron-rich Rh δ– species, while holes remain on CeO 2 -NS to induce interfacial oxygen vacancies (O v ). These vacancies serve as dynamic active sites that lower the energy barrier for CO 2 dissociation, promote *CH 3 O oxidation, and facilitate *CO desorption. The ultrathin nanosheet architecture further lowers the O v formation energy and improves charge separation efficiency, enabling dynamic vacancy generation under a low photon flux. This work establishes a general strategy for integrating light-induced charge separation with defect-mediated thermal chemistry to overcome kinetic limitations in thermodynamically demanding reactions, offering a pathway toward efficient solar-driven reforming.