Hybrid‐Secondary Ion Mass Spectrometry Probes Atomic‐Scale Insight Into Selective C─C Bond Cleavage in PET Upcycling

ABSTRACT Herein, we present a rapid CO 2 laser irradiation approach to stabilize Ru single‐atoms (Ru–SAs) on two‐dimensional NiO nanosheets (Ru–SA/NiO). Laser treatment (λ ≈ 10.6 µm, power ≈ 7 W) induces oxygen vacancies in NiO, promotes interfacial electron transfer from NiO to Ru–SAs, and optimizes ethylene glycol (EG) oxidation reaction (EGOR) critical intermediate adsorption, where EG is the primary polyethylene terephthalate (PET)‐derived monomer. This study establishes hybrid secondary ion mass spectrometry (hybrid‐SIMS, integrating time‐of‐flight SIMS and Orbitrap‐SIMS) as a powerful platform for mechanistic elucidation of EGOR, enabling identification of bias‐conditioned surface‐bound EGOR intermediates. Combined in situ spectroelectrochemical analyses and theoretical calculations reveal a stepwise oxidative dehydrogenation mechanism involving sequential O─H and C─H activation that promotes controlled C─C bond cleavage during PET upcycling. The synergistic Ru–SA–NiO interface preferentially stabilizes C 1 intermediates, delivering highly selective formate generation with a Faradaic efficiency of 86.37% and a yield rate of 0.18 mmol h −1  cm −2 at 1.6 V versu RHE, with excellent stability over 300 h. Technoeconomic analysis further confirms the viability of PET upcycling. This work delivers new insights into the role of surface‐adsorbed intermediates and new perspectives for catalyst design for plastic upcycling toward a circular economy.