Chemical upcycling of waste surgical face masks into high surface area activated carbon for energy storage and electrocatalysis.

The spread of COVID-19 led to a huge increase in the generation of polypropylene-based surgical face masks (SFMs) worldwide, leading to landfills and causing severe pollution of resources and the atmosphere when incinerated. In addition, the current treatment methods yield minimal carbon. Therefore, there is a growing need to upcycle waste SFMs into value-added products through safe and environmentally benign processes. In this study, waste SFMs were upcycled into activated carbon (AC) through a series of processes including sulfonation, pre-carbonization and activation with KOH at varying temperatures. The surface functionalities and textural properties of the resulting AC samples were thoroughly characterized using vibrational spectroscopy, N2 sorption and microscopic studies. As the activation temperature increased, the porosity and surface area of the AC also increased. Notably, AC derived from SFMs upcycled at an activation temperature of 950°C (AC-950) exhibits an exceptionally high surface area of 2163 m2 g−1, promising oxygen reduction reaction (ORR) activity (high onset potential of 932 mV and limiting current density of 16.6 mA cm−2), comparable to the benchmark Pt/C electrocatalyst. In addition, it displays a commendable supercapacitor behaviour (specific capacitance of 236 F g−1 at 1 A g−1, good rate retention and cycle-life). [ABSTRACT FROM AUTHOR]