Unveiling the latent potential: Ni/CoFe2O4-loaded electrospun PVDF hybrid composite-based triboelectric nanogenerator for mechanical energy harvesting applications

This study investigates the potential of Ni-doped cobalt ferrite (CoFe₂O₄, N-CF) nanoparticles (NPs)-loaded electrospun poly(vinylidene fluoride) (PVDF) composites for triboelectric nanogenerators (TENGs) to efficiently harness electrical energy from low-frequency mechanical vibrations. PVDF was chosen for its strong electroactive polar phase and inherent tribo-negative properties. Cobalt ferrite (CF) NPs exhibit exceptional charge-trapping capabilities, while nickel’s metallic nature minimizes triboelectric losses due to its conductivity. The synergistic effects of Ni-doped CF (N-CF) fillers enhance charge-trapping efficiency and reduce triboelectric losses, significantly boosting TENG performance. Nickel oxide (NiO), CF, and N-CF NPs were synthesized using a facile co-precipitation method, and PVDF composites were fabricated through electrospinning. The physical and crystalline properties of the composites were characterized using various spectroscopic techniques. Results indicated that incorporating 3 wt% N-CF into PVDF optimized the β-crystalline phase content, crucial for improved output performance. Electrospun PVDF/N-CF (PNC) nanocomposite mats served as the tribo-negative (TN) layer, while aluminum (Al) electrode acted as the tribo-positive (TP) layer in TENG device fabrication. Electrical measurements showed that pristine PVDF/Al TENG devices exhibited lower performance (open-circuit potential—Voc = 22 V, short-circuit current—Isc = 0.61 µA) compared to the optimized Al/PNC3 TENG devices (Voc = 421 V, Isc = 1.0 µA). The importance of a spacer gap was emphasized, with devices incorporating a spacer gap demonstrating superior performance. The optimized TENG device successfully powered over 30 light-emitting diodes and a stopwatch in real-time applications. This study highlights the exceptional output performance of Al/PNC3-based TENGs and provides valuable insights into the development of next-generation sustainable energy harvesting materials.