The rapid uptake of energy harvesting triboelectric nanogenerators (TENGs) for self-powered electronics requires the development of high-performance tribo-materials capable of providing large power outputs. This work reports on the synthesis and use of aniline formaldehyde resin (AFR) for energy-harvesting applications. The facile, acidic-medium reaction between aniline and formaldehyde produces the aniline-formaldehyde condensate, which upon an in-vacuo high temperature curing step provides smooth AFR films with abundant nitrogen and oxygen surface functional groups which can acquire a tribo-positive charge and thus endow AFR with a significantly higher positive tribo-polarity than the existing state-of-art polyamide-6 (PA6). A TENG comprising of optimized thin-layered AFR against a polytetrafluoroethylene (PTFE) film produced a peak-to-peak voltage of up to ~1,000 V, a current density of ~65 mA m-2, a transferred charge density of ~200 μC m-2 and an instantaneous power output (energy pulse) of ~11 W m-2 (28.1 μJ cycle-1), respectively. The suitability of AFR was further supported through the Kelvin probe force microscopy (KPFM) measurements, which reveal a significantly higher average surface potential value of 1.147 V for AFR as compared to 0.87 V for PA6 and a step-by-step increase of the surface potential with the increase of energy generation cycles. The work not only proposes a novel and scalable mouldable AFR synthesis process but also expands with excellent prospects, the current portfolio of tribo-positive materials for triboelectric energy harvesting applications.
N. Soin gratefully acknowledges the partial financial support received from the National Research Foundation ( NRF ), South Africa (Grant No. ECR180426324617 ). Authors N. Soin, J. Luo and C. H. See would also like to acknowledge the support received from University of Bolton through the Jenkinson Award scheme. The authors would also like to thank Dr John Benson at the Ulster University for his help with some initial XPS measurements. XPS data collection was performed at the EPSRC National Facility for XPS (‘HarwellXPS’), operated by Cardiff University and UCL, under contract No. PR16195. Appendix A
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- Aniline formaldehyde resins
- Surface potential
- Tribo-positive polymers
- Triboelectric nanogenerators