Electrochemical Degradation of Plastic Waste Coupled with Hydrogen Evolution in Seawater Using Rosette-Like...

Plastic overproduction and improper disposal generates over 390 million tons of waste annually, severely polluting marine ecosystems. Polyglycolic acid (PGA) is widely used in biomedical and packaging fields. Here, this study introduces an electrochemical degradation strategy for PGA waste that couples its conversion with seawater-driven hydrogen evolution reaction (HER) using rosette-like high-entropy NiCoFeMnAlO_x nanosheets (r-NCFMAO). The PGA-derived glycolic acid oxidation reaction (GAOR) achieves 100 mA cm^-2 at 1.36 V versus RHE, benefiting from abundant hydroxyl species (OH*) that lower the required potential by over 190 mV compared to the oxygen evolution reaction. This method produces ≈90% CO₃ ^2-, and subsequent Ca²⁺ precipitation recovers 77% of CaCO₃, a valuable material in construction and papermaking. Electrochemical analysis, quasi in situ electron paramagnetic resonance, and in situ Raman spectroscopy reveal continuous OH^- oxidation enhancing GAOR activity, while density functional theory confirms that OH* lowers the energy barrier for the rate-determining C─C bond cleavage and C─H bond activation. The integrated GAOR ‖ HER system sustains performance for over 300 h at industrial current densities and is applicable to upcycling various plastics. This work pioneers a synergistic approach for plastic waste valorization and hydrogen production, advancing circular carbon strategies.