ZnO/PVDF-HFP <i>Setaria viridis</i> Structure-Based Triboelectric Nanogenerators for Mechanical and Blue Energy Harvesting

Green energy harvesting is a sustainable and renewable solution for the power generation of small portable electronic devices. Triboelectric nanogenerators (TENGs) have garnered significant attention as promising technologies due to their straightforward design, low cost, and suitability to collect low-frequency mechanical energy. Herein, a simple approach is proposed that combines electrospinning and a hydrothermal method to grow ZnO nanorods (NRs) on PVDF-HFP nanofibers (NFs). Growing ZnO NRs on PVDF-HFP NFs has formed Setaria viridis structures that enhance surface roughness. Additionally, surface modification through fluorination reduces the surface energy, thereby increasing the hydrophobicity. The resulting 1.0 wt % ZnO/PVDF-HFP TENG achieved remarkable performance, with an output voltage of 1200 V and a current density of 1.34 μA/cm2, which is 4.68 times higher than pristine PVDF-HFP TENG. This significant improvement is attributed to the enhancement of the β phase of PVDF-HFP and the increased dielectric constant resulting from the growth of ZnO NRs on the PVDF-HFP NFs. In addition, the modified TENG demonstrated excellent capability for energy conversion from water droplets, yielding a maximum output voltage of 28 V and a current of 33 μA under optimized conditions (20 cm distance, 0.13 mL/s flow rate, and 45° water flow angle). This work highlights the significant potential of ZnO-modified PVDF-HFP NFs for the development of advanced contact separation mode TENGs, enabling continuous power generation through mechanical motion, as well as water droplet energy harvesting.