In a recent article published in Small, researchers introduced a method for fabricating sustainable triboelectric nanogenerators (TENGs) using recycled polyethylene terephthalate (PET) in combination with nylon and titanium dioxide nanoparticles (TiO2 NPs) to improve performance.
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Background
TENGs convert mechanical energy into electrical energy and are being explored as a sustainable energy solution, particularly for miniaturized devices. Traditional TENG materials lack sustainability, creating a need for environmentally friendly alternatives. TENG operation relies on the triboelectric effect, where two materials generate electrical charges through contact.
Material selection significantly influences TENG efficiency. Nylon 6,6 acts as an electron donor, while recycled PET is used as the triboelectric negative material due to its availability and cost-effectiveness. However, PET exhibits lower triboelectric properties than materials such as polytetrafluoroethylene (PTFE) and polypropylene.
Incorporating TiO2 NPs enhances dielectric properties and overall TENG efficiency. TiO2 NPs possess exceptional dielectric characteristics and have applications in various fields, including photocatalysis and water purification. This research utilizes electrospinning to create hybrid nanofibers, combining the strengths of recycled PET and nylon to promote sustainability while improving the performance of TENG devices.
Experimental Methodology
The fabrication of electrospun nanofibers involved several stages. Waste PET bottles were shredded and purified, followed by the preparation of a 15 % (w/v) PET solution in a trifluoroacetic acid (TFA) and dichloromethane (DCM) solvent mixture. Electrospinning produced uniform nanofibers from this solution.
TiO2 NPs were incorporated by dispersing them in the polymer solution before electrospinning to achieve uniform distribution in the nanofiber matrix. Various TENG configurations were tested, including pristine PET, PET with TiO2 NPs, pristine nylon 6,6, and nylon with TiO2 NPs at different concentrations.
Electrospinning was conducted under high voltage, facilitating nanofiber formation and deposition onto a rotating collector. The resulting nanofibers and TENG devices underwent structural, thermal, mechanical, and electrical characterization using microscopy, spectroscopy, and other analytical techniques.
Results and Discussion
Electrospun nanofibers exhibited improved uniformity, with minimal beading following TiO2 NP incorporation. The addition of TiO2 NPs enhanced mechanical stability and thermal properties.
Electrical characterization showed that the most effective TENG configurations achieved a peak power density of 23.44 mW/m², a maximum output voltage of 111 V, and a surface charge density of 6.81 μC/m². The PET-TiO2 NP combination generated higher energy output compared to traditional configurations. This performance increase was attributed to the role of TiO2 NPs in enhancing the effective dielectric constant, improving charge separation during mechanical contact cycles.
Hybrid nanofiber mats incorporating TiO2 NPs demonstrated higher output voltage and current than pristine PET or nylon counterparts. The integration of TiO2 NPs contributed to improved energy harvesting efficiency alongside increased mechanical and thermal stability.
This study highlighted the role of nanostructured surfaces in optimizing energy output by increasing the surface area available for triboelectric charge generation. Future research could explore additional recycled materials and alternative nanostructures to further optimize TENG functionality. The improved energy output, mechanical strength, and thermal stability of nanofiber-based TENGs make them suitable for applications in wearable electronics and self-powered sensors.
Journal Reference
Thomas-Kochakkadan S., et al. (2025). Sustainable Electrospun Hybrid Nanofibers for Triboelectric Nanogenerators. Small. DOI: 10.1002/smll.202410271, https://onlinelibrary.wiley.com/doi/10.1002/smll.202410271