Highly efficient conversion of waste plastic into thin carbon nanosheets for superior capacitive energy storage

The wide application of carbon nanosheets (CNS) is still restricted by low production. Meanwhile, the accumulation of waste plastic generates serious environmental pollution. Nowadays, the conversion of waste plastic into two-dimensional CNS is regarded as a promising way to address these issues due to the high carbon content of waste plastic. However, this conversion process is still impeded by low-efficient catalysts so far. Herein, the highly efficient carbonization of waste polypropylene (PP) into CNS is achieved using a combined catalyst of ferrocene and sulfur. The carbonization process in sealed space ensures an ultrahigh carbon yield (62.8%) and a thin thickness (4-4.5 nm) of as-prepared CNS, even though little catalyst is used. After activation, the activated carbon nanosheets (ACNS) show a well-defined hierarchical porous structure with a large specific surface area (3200 m(2) g(-1)) and a big pore volume (3.71 cm(3) g(-1)). The ACNS based electrode delivers a high specific capacitance of 349 F g(-1) at 0.5 A g(-1). The fabricated symmetric supercapacitor manifests a high energy density of 23 Wh kg(-1) at 225 W kg(-1). These findings provide a reference for the efficient conversion of waste plastic into energy storage materials. (C) 2020 Elsevier Ltd. All rights reserved.