Abstract

Upcycling polyethylene terephthalate (PET) into value-added products via electrochemical oxidation of PET hydrolysate provides a sustainable pathway toward a circular plastic economy and an alternative to conventional mechanical recycling. Herein, we present a rapid and one-step CO₂ laser irradiation strategy that stabilizes Ru single atoms (RuSAs) on two-dimensional Co₃O₄ nanosheets (RuSA/Co₃O₄) within 3 min under ambient conditions. The Co₃O₄ substrate was derived from microwave-synthesized α-Co(OH)₂ (2.45 GHz, 1 min) followed by thermal oxidation at 350°C for 1 h, affording a spinel oxide with ordered Co²⁺/Co³⁺ sites. Unlike conventional high-temperature or multistep approaches for single-atom catalysts (SACs), CO₂ laser irradiation simultaneously generates oxygen vacancies within the Co₃O₄ lattice and decomposes Ru precursors, enabling defect-mediated stabilization of RuSAs through strong Ru–O–Co electronic interactions without external coordinating ligands. Distinct from carbon-supported SAC systems, the oxide support functions as both anchoring matrix and active redox component during ethylene glycol oxidation reaction (EGOR). Combined experimental and theoretical analyses reveal that α-Co(OH)₂ promotes C₂-selective C–H bond oxidation to glycolate, Co₃O₄ favors C–C bond cleavage toward C₁ products (formate), and RuSA/Co₃O₄ enables tunable and balanced C₁/C₂ selectivity during the EGOR, highlighting the role of RuSA sites in regulating EGOR pathways with excellent stability over 100 h. Beyond the EGOR, practical PET waste upcycling was demonstrated using PET hydrolysate feedstock; the RuSA/Co₃O₄ catalyst achieves high recovery yields of terephthalic acid (88.0%), formate as potassium diformate (90.6%), and glycolate as potassium glycolate glycolic acid (91.3%). This study elucidates laser-induced defect–SA interactions for rapid SAC fabrication and establishes an integrated platform coupling SA engineering with plastic waste upcycling.