High-yield, one-pot upcycling of polyethylene and polypropylene waste into blue-emissive carbon dots

The COVID-19 pandemic has led to unprecedented demand for single-use plastics such as plastic bags and surgical masks. Plastics are resistant to natural degradation and are a global environmental pollution problem, threatening the environment and human health. Finding suitable ways to convert plastic waste into valuable materials is crucial to mitigate these effects. Herein, we report a facile, single-step, and organic solvent-free hydrothermal process to convert polyethylene-based plastic bags and polypropylene-based surgical masks into carbon dots with a 96% production yield. The produced CDs are soluble in aqueous and various organic solvents, show excitation-dependent emission consistent with their size of 1-8 nm and exhibit thermal and photostability. We further show how this oxidative degradation approach can upcycle contaminated plastics with organic waste, which is a major challenge with plastic recycling. Finally, we demonstrate a potential use case of CDs as anticounterfeiting agents using fluorescent, stretchable films of CD-doped polydimethylsiloxane (PDMS). This synthesis method is a cost-effective, easy-to-implement, highly scalable, and contamination-resistant approach to upcycle plastic waste.