Co-etching effect to convert waste polyethylene terephthalate into hierarchical porous carbon toward excellent capacitive energy storage

With the ever-increasing consumption of polyethylene terephthalate (PET) related products, how to recycle the waste PET still remains as a great challenge for the sustainable development. Converting waste PET into porous carbon material has been emerged as a promising way to address this issue. Recently, the microporous carbon derived from waste PET has drawn considerable attention in adsorption field, but its electrochemical application is still impeded by low specific surface area (SSA <1500 m2 g−1) and small meso-/macropores volume (<0.2 cm3 g−1). Herein, hierarchical porous carbon (HPC) is successfully prepared from waste PET. The obtained HPC possesses a high SSA (2238 m2 g−1) and a large meso-/macropores volume (0.51 cm3 g−1). The formation mechanism of hierarchical porous structure is proposed: co-etching effect of sp2/sp3 hybridized carbon produces micropores and meso-/macropores, respectively. In a three-electrode configuration, HPC based electrode achieves an outstanding capacitance of 413 F g−1, while the traditional microporous carbon exhibits a low capacitance of 142 F g−1. The fabricated symmetric supercapacitor shows a high energy density of 25 Wh kg−1. This work provides a good reference to convert waste plastics into hierarchical porous carbon.