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

Herein, we present a rapid CO₂ 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 C₁ 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.