Ruthenium Single Atom Switches the Interfacial Mechanism to Mars–van Krevelen for Coking-Resistant Photothermocatalytic Reforming of (Micro)Plastics with CO2

Abstract Photothermal dry reforming of polyethylene (PE) with carbon dioxide (CO2) is a promising route for waste plastic and greenhouse gas valorization, but mismatched PE cracking and CO2 activation kinetics cause coke deposition and limit reforming stability. Here, we develop a photothermal catalyst, Ru1Cun/TiO2–x, that enables efficient and stable conversion of PE and CO2 into syngas under simulated and natural sunlight across diverse plastic feedstocks. Mechanistic studies show that Ru single atoms reconstruct the Cu-TiO2–x interface, shifting the reaction from a Langmuir–Hinshelwood mechanism to a Mars–van Krevelen (MvK) pathway that strengthens CO2 activation and lattice oxygen cycling, thereby directing PE-derived intermediates through sequential oxidation before dehydrogenation and suppressing coke formation. Life-cycle assessment and scale-up simulations show that solar-driven photothermal co-reforming has a lower carbon footprint than conventional plastic upcycling, supporting its feasibility and scalability for solar-driven plastic waste remediation and greenhouse gas utilization.