Novel synthesis of ultrasmall hollow carbon nanospheres

Hollow carbon nanospheres (HCNSs) are characterized by muti-layered carbon shells with sp² hybridized bonds enclosing a spherical cavity. These shell structures, often embedded with defective microchannels or mesopores, possess a high specific surface area and a tunable electronic structure. Compared with nanocarbons with seamless shapes, such as fullerene, carbon nanotubes, and graphene, HCNSs render an innovative platform for applications inelectrochemical energy storage and conversion, biological molecular packaging, and drug delivery. However, developing straightforward and scalable methods for synthesizing such structures remains challenging. In this study, we present a novel single-step method for synthesizing HCNSs with a uniform diameter of 10 nm. Various polymers have been demonstrated as efficient carbon sources, with nanometer-thin copper film as the effective catalyst in this method. The resulting carbon structure comprises graphitic HCNSs and a supporting network of amorphous carbon films, as confirmed by transmission electron microscopy, electron energy loss spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy.We also examined the growth mechanism and dynamics and found the interaction of polymer and copper surface atoms at intermediate temperatures playing a vital role in forming the HCNSs. This novel synthesis approach simplifies the production process and ensures the uniformity and quality of the hollow carbon spheres, making it a promising method for large-scale applications.