Controllable Carbonization of Plastic Waste into Three-Dimensional Porous Carbon Nanosheets by Combined Catalyst for High Performance Capacitor.

Polyethylene terephthalate (PET) plastic has been extensively used in our social life, but its poor biodegradability has led to serious environmental pollution and aroused worldwide concern. Up to now, various strategies have been proposed to address the issue, yet such strategies remain seriously impeded by many obstacles. Herein, waste PET plastic was selectively carbonized into three-dimensional (3D) porous carbon nanosheets (PCS) with high yield of 36.4 wt%, to be further hybridized with MnO2 nanoflakes to form PCS-MnO2 composites. Due to the introduction of an appropriate amount of MnO2 nanoflakes, the resulting PCS-MnO2 composite exhibited a specific capacitance of 210.5 F g-1 as well as a high areal capacitance of 0.33 F m-2. Furthermore, the PCS-MnO2 composite also showed excellent cycle stability (90.1% capacitance retention over 5000 cycles under a current density of 10 A g-1). The present study paved an avenue for the highly efficient recycling of PET waste into high value-added products (PCSs) for electrochemical energy storage.