Upcycling Plastic Waste Into Durable and Low‐Cost Energy Harvesting Devices

ABSTRACT The increase in plastic production, waste accumulation, and poor disposal practices has created serious environmental concerns. This study presents a simple route for harvesting mechanical energy from post‐consumer polymeric waste by using the recovered polymer itself as the active layer in a triboelectric nanogenerator (TENG). Five waste polymers, polyethylene terephthalate (PET), polyester, vinyl, nitrile, and low‐density polyethylene (LDPE), were processed into flat sheets and paired with recycled aluminum foil electrodes in a contact–separation configuration. Spectroscopic, microscopic, thermal, surface‐potential, roughness, and mechanical analyses were used to understand how material type and processing condition affected the triboelectric response. Among the tested materials, thermally processed PET showed the most stable output, generating an open‐circuit voltage of 60 V at 5 Hz and more than 90 V under 50 N load, while maintaining stable voltage output over 12 500 contact–separation cycles. The optimized PET device produced a maximum measured output power of 21.7 µW at 210 kΩ, corresponding to a power density of 0.9 µW cm −2 , and charged a 10 µF capacitor to 4.2 V within 30 s. The results show that waste PET can be reused as a durable triboelectric layer for low‐power sensing and small‐scale energy‐harvesting demonstrations.