Triboelectric nanogenerator based on cellulose nanocrystals and graphene for energy harvesting from piano playing motion

The increasing global energy demand and environmental concerns have spurred the development of sustainable energy solutions. Among these, the triboelectric nanogenerator (TENG) has emerged as a promising technology for capturing mechanical energy from the environment. However, achieving a balance between energy harvesting and environmental sustainability remains challenging. Cellulose nanocrystals (CNCs), known for their high surface-to-volume ratio, mechanical strength, and biocompatibility, show potential as eco-friendly triboelectric materials. Graphene, as an electrode material in TENGs, offers efficient energy conversion, durability, and environmental benefits. In this study, we developed TENGs using CNCs as triboelectric layers in singleelectrode mode, in conjunction with graphene electrodes and paired with nitrile or PTFE as counter triboelectric layers. We investigated how CNC layer thickness and chemical functionalization affect TENG performance in terms of output current, voltage, and power. The highest power density achieved was 0.4 W/cm(2) using CNCs functionalized with octylamine groups and PTFE. Remarkably, this TENG demonstrated excellent long-term stability, maintaining consistent output signals over three years. Utilizing this high-performance TENG, we efficiently harvested biomechanical energy from piano playing, storing it in a capacitor for use as a power source in various devices.