Interfacial Polarization and Dual Charge Transfer Induced High Permittivity of Carbon Dots-Based Composite as Humidity-Resistant Tribomaterial for Efficient Biomechanical Energy Harvesting

Tribopositive, scalable, and biocompatible materials are highly desired for high-performance triboelectric nanogenerators (TENGs). In this study, polyethylenimine (PEI) functionalized N-doped carbon dots (NCDs-PEI) are synthesized and a novel approach to develop high-output TENGs by incorporating high permittivity NCDs-PEI into polyvinyl alcohol (PVA) as the tribopositive composite (CPP composite) is proposed for the first time. By systematically manipulating the mass ratio of NCDs/PVA and PEI-functionalized concentration, the optimized CPP composite-based TENGs (CPP-TENGs) reveal a remarkable enhancement in power density by 28.5 times as compared with pure PVA-based TENGs. The considerable electric outputs of CPP-TENGs can be attributed to the synergistic effect of interfacial polarization enhanced permittivity of CPP composite and boosted surface charge density induced by dual charge transfer pathways. Moreover, CPP-TENGs present superior high-output stability, durability, and humidity-resistance, and can also effectively drive electronics at different humidity and monitor human body movements. This work renders a simple, feasible, and scalable pathway to boost the electrical performance of TENGs for biomotion energy harvesting as well as providing insights for exploiting novel tribomaterials in the development of high-output TENGs.