Phycocyanin and cellulose nanofibril-based biodegradable triboelectric-piezoelectric hybrid nanogenerators with high-output performance

Abstract In this study, a biodegradable and sustainable piezoelectric–triboelectric hybrid nanogenerator (HENG) was designed and fabricated using cellulose nanofibrils (CNFs) as a nucleating agent and phycocyanin (PC), an algae-derived protein from Spirulina platensis, as the tribo-positive layer paired with poly(vinylidene fluoride) (PVDF) films. The investigation was conducted in two parts to investigate the effect of CNF incorporation into different layers. In the first part, CNFs were incorporated into the PVDF layer, whereas in second part incorporated into the PC layer. Electromechanical performance was characterized under periodic contact–separation motion. Even in the absence of nanofillers, the PVDF–PC pair exhibited efficient electromechanical behavior, generating an open-circuit voltage (V _oc ) of 84 V and a short-circuit current (I _sc ) of 87 µA. Upon CNF incorporation, the output was significantly enhanced. The highest performance was observed when CNFs were added to the PVDF layer (at 20 wt.% CNFs loading) with V _oc and I _sc values of 228 V and 199 µA, respectively. On the other hand, when CNFs were incorporated into the PC layer and paired with neat PVDF, the maximum output reached 128 V and 126 µA (at 5 wt.% CNFs). This outcome highlights that CNFs contribute more effectively to performance improvement in PVDF than in PC.