Electroactive phase dependent triboelectric nanogenerator performance of PVDF-TiO2 composites

Abstract

This investigation explores the impact of the electroactive phase of a well-known tribonegative polymer, polyvinylidene fluoride (PVDF), on its triboelectric behaviour by compositing it with anatase, rutile, and mixed-phase TiO2 nanoparticles. PVDF-TiO2 polymer composite films with TiO2 having different crystalline phases were prepared by spin coating. TENG specimens were fabricated using the prepared films and tested for their TENG properties in contact separation mode by pairing them with ITO-coated PET substrates. The XRD and FT-IR results show that the TiO2 nanoparticles with rutile phase imparted the highest percentage of β crystalline phase in PVDF compared to that of the anatase and mixed phase. The difference in surface roughness of PVDF-TiO2 composites was also observed with the change in the crystalline phase of the incorporated TiO2 nanoparticles in the polymer matrix. The TENG studies suggest that the PVDF incorporated with rutile TiO2 shows the highest output voltage (peak-peak ～105 V at 60N force) compared to all the other PVDF-TiO2 composites at specified contact forces and frequencies, whereas PVDF incorporated with anatase TiO2 and a mix of anatase and rutile TiO2 showed peak-peak voltages of ～82 V and ～33 V respectively. These results offer insights into the crystalline phase-dependent triboelectric behaviour of polymers and the enhancement of their TENG performance through the tuning of polymer crystalline phases using fillers.