Upcycling of surgical facemasks into carbon based thin film electrode for supercapacitor technology

Polypropylene (PP), a commonly used plastic, is used for making the outer layers of a surgical face mask. In 2020, around 3 billion surgical face masks were disposed into the environment, causing a huge threat to wildlife, aquatic life, and ecosystems. In this work, we have reported the sulfonation technique for stabilizing the surgical face masks and their conversion into carbon nanoparticles for application as a supercapacitor electrode. The electrode is fabricated by preparing a slurry paste of carbon nanoparticles and pasting it on a conductive wearable fabric. To investigate the performance of the carbon thin film electrode, electrochemical techniques are employed. The Cyclic Voltammetry (CV) analysis performed at different scan rates in a 6 molar KOH electrolyte reveals that the carbon thin film acts as a positive electrode. At 4 A g^-1, the electrode shows a specific capacitance of 366.22 F g^-1 and 100% retention of specific capacitance for 8000 cycles. A two-electrode asymmetric device is fabricated using carbon thin film as the positive electrode, NiO thin film as the negative electrode, and a KOH separator between two electrodes. The device shows a specific capacitance of 113.73 F g^-1 at 1.3 A g^-1 and glows a red LED for 6 min. This work is a step towards upcycling the waste produced from surgical face masks used during the COVID-19 pandemic and its application for energy storage.