Nano hollow carbon regulated by carbon dots as a high-performance anode for potassium and sodium ion battery

In this paper, carbon dots (CDs) derived from citrus peel were used as regulators to adjust the size of template SiO2 and further prepare hollow carbon spheres with different diameter. During the synthesis process of SiO2 templates, the abundant surface functional groups of CDs interact strongly with the functional groups (hydroxyl groups, etc.) possessed by silicic acid and TEOS, thereby inhibiting the growth of SiO2 spheres. By changing the content of CDs added, the size of the SiO2 template changes accordingly. A series of nano-hollow carbon spheres were prepared through high-temperature treatment of as-obtained SiO2 spheres coated with PDA and then acid washing. Among them, HCN-60 with optimized size and hollow structure exhibited excellent potassium/sodium storage performance. This research provides a new idea for the rational design of high-performance carbon anodes.