Porous Carbon Nanosheet with High Surface Area Derived from Waste Poly(ethylene terephthalate) for Supercapacitor ApplicationsYanliang Wen, Krzysztof Kierzek, Jiakang Min, Xuecheng Chen*, Jiang Gong*, Ran Niu, Xin Wen, Jalal Azadmanjiri, Ewa Mijowska and Tao Tang*

Converting waste plastics into valuable carbon materials has obtained increasing attention. And carbon materials have shown to be the ideal electrode materials for double-layer supercapacitors owing to their large specific surface area, high electrical conductivity, and stable physicochemical properties. Herein, an easily operated approach is established to efficiently convert waste poly(ethylene terephthalate) (PET) beverage bottles into porous carbon nanosheet (PCNS) through the combined processes of catalytic carbonization and KOH activation. PCNS features an ultrahigh specific surface area (2236 m2 g-1), hierarchically porous architecture, and a large pore volume (3.0 cm3 g-1). Such excellent physicochemical properties conjointly contribute to the outstanding supercapacitive performance: 169 F g-1 (6 M KOH) and 135 F g-1 (1 M Na2SO4). Furthermore, PCNS shows a high capacitance of 121 F g-1 and a corresponding energy density of 30.6 Wh kg-1 at 0.2 A g-1 in the electrolyte of 1 M TEATFB/PC. When the current density increases to 10 A g-1, the capacitance remains at 95 F g-1, indicating the extraordinary rate capability. This work not only proposes a facile approach to synthesize PCNS for supercapacitors, but also puts forward a potential sustainable way to recycle waste plastics and further hopefully mitigates the waste plastics-related environmental issues.