Biomass-based carbon nanofibers enhanced by carbon quantum dots for high-performance supercapacitors and moist-electric generators

Developing a simple and effective method for optimizing lignin structure is a key challenge for the application of biomass-based carbon nanofibers in energy storage and moisture-enabled electricity generation fields. In this work, an effective strategy is designed to prepare novel biomass-based carbon nanofibers. Carbon quantum dots (CQDs) are introduced as functional components into biomass-based carbon nanofibers to optimize the inherent structural defects of lignin. The introduction of CQDs effectively reduces the interaction between lignin macromolecules, thereby increasing the flexibility of lignin macromolecule chain segments. The obtained biomass-based carbon nanofibers exhibit excellent microfiber morphologies and a high degree of graphitization. The specific capacitance and energy density for biomass-based carbon nanofibers as the energy storage device reach 294.4 F/g and 28.3 W h/kg, respectively. Furthermore, the biomass-based moist-electric generator shows high power generation efficiency, the output voltage and output current of a single device reach 0.75 V and 1.8 μA, respectively. Notably, as the number of biomass-based moist-electric generators in series or parallel increases, the overall output efficiency of the device system has a linear relationship, which means that a sufficient number of biomass-based moist-electric generator devices can meet the power supply requirements of larger power systems. This work puts forward a promising strategy to prepare low-consumption, high-performance, and environmentally friendly biomass-based carbon nanofibers for the supercapacitors and moist-electric generators.