Active chloride-mediated PET microplastic depolymerization via ferroelectric electrocatalysis: Unveiling the dark reaction boosting mechanism

Efficient reforming of polyethylene terephthalate (PET) microplastics is crucial for addressing environmental challenges. The emerging active Cl· mediated PET depolymerization reaction represent a promising sustainable pathway, but suffers from low reaction kinetics and strict high temperatures ionic liquid reaction conditions. Herein, we propose a unique ferroelectric-enhanced chlorine-mediated depolymerization strategy for PET microplastics under ambient aqueous conditions. A ferroelectric PVDF-TrFE-CFE@TiO 2 (abbreviated as CFE@TNTs) electrode was fabricated by integrating poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVDF-TrFE-CFE) with TiO 2 nanotubes array, which is employed in an electrolyte composed of a mixed solution of sodium hypochlorite and sodium hydroxide. Remarkably, a significant decrease in the molecular weight of PET was observed after electrocatalytic depolymerization using the CFE@TNTs electrode under dark conditions. Characterization (XRD, Raman, XPS, FTIR) showed the electrode in darkness continuously activated chloride ions into active chlorine species. Leveraging electrons released from the PET depolymerization process, the electrode's polarization field drives the directional electron transfer, thereby lowering the bond dissociation energy barrier and accelerating the reaction kinetics. In contrast, excessive light exposure promotes unwanted photochemical side reactions that lead to the consumption of Cl·. Product analysis confirmed that PET microplastics were successfully depolymerized into terephthalic acid and 1,2-dichloroethane. Density functional theory (DFT) revealed that the intrinsic polarization field of CFE@TNTs enhances interfacial charge separation and Cl − activation and lowers energy barriers. Breaking from traditional light-driven pathways, this study demonstrates efficient PET depolymerization under ambient aqueous dark conditions via ferroelectric catalysis, where polarization enhances active Cl· generation. This approach pushes ferroelectric materials for microplastic treatment and supports the development of energy-efficient, selective plastic recycling.