Upcycling Polyethylene Terephthalate-Derived CoNi–Metal–Organic Framework MoSe2 Hybrids for High-Performance Aqueous Supercapacitors

Abstract

This study presents a novel technique for sustainably upcycling polyethylene terephthalate (PET) plastic waste (PW) into functional metal–organic frameworks (MOFs) for enhanced energy storage applications. To synthesize CoNi–MOF nanocrystals, terephthalic acid (TPA), which is obtained by alkaline hydrolysis of PET, acts as an environmentally benign organic linker. Further integrating the MOFs with ultrathin MoSe2 nanosheets using a simple hydrothermal technique develops a hybrid CoNi–MOF MoSe2 electrode material. The synthesized nanocomposite demonstrates excellent cycling durability, maintaining 98.46% of its capacitance after 15,000 galvanostatic charge-discharge cycles, along with a high specific capacitance of 3322 F g−1 at a low current of 0.5 A g−1. Furthermore, an asymmetric supercapacitor (ASC) device is constructed with activated carbon (AC) as the anode and CoNi–MOF MoSe2 as the cathode in an aqueous KOH electrolyte. This ASC has exceptional electrochemical performance, maintaining 95% of its original capacity after extended cycling and producing a high energy density of 59 Wh kg−1 at a power density of 450 W kg−1. This work highlights the possibility of PW-derived hybrid MOF materials with programmable nanostructures as viable choices for upcoming improved energy storage technologies.