Carbon dots modified Ti₃C₂T_x-based fibrous supercapacitor with photo-enhanced capacitance

The energy crisis has always been a widely concerned problem. It is an urgent need for green and renewable energy technologies to achieve sustainable development, and the photo-assisted charging energy storage devices provide a new way to realize the sustainable utilization of solar energy. Here, we fabricated a photo-assisted charging fibrous supercapacitor (NM₂P₁) with Ti₃C₂T_x-based hybrid fibre modified by nitrogen-doped carbon dots (NCDs). The NM₂P₁ fibre provides a volumetric capacitance of 1, 445 F·cm^-3 (630 F·g^-1) at 10 A·cm^-3 under photo-assisted charging, which increases by 35.9% than that of dark condition (1, 063 F·cm^-3/ 464 F·g^-1). Furthermore, the NM₂P₁ fibrous supercapacitor device shows that the maximum volumetric energy density and volumetric power density are 18.75 mWh·cm^-3 and 8, 382 mW·cm^-3. Notably, the transient photovoltage (TPV) test was used to further confirm that NCDs as a photosensitizer enhance the light absorption capacity and faster charge transfer kinetics of NM₂P₁ fibre. This work directly exploits solar energy to improve the overall performance of supercapacitor, which opens up opportunities for the utilization of renewable energy and the development of photosensitive energy equipment.