Engineering hollow carbon spheres: directly from solid resin spheres to porous hollow carbon spheres via air induced linker cleaving

Hollow carbon spheres (HCSs) have broad application in many fields such as catalysis, adsorption and energy storage. Due to various restrictions on hard and soft templates, self-templating methods have received extensive attention. Generally, the conventional self-templating method includes two steps, including the hollowing and carbonization process. Herein, a facile novel one-step air induced linker cleaving (AILC) method was developed to synthesize HCSs using 3-aminophenol formaldehyde (APF) resin spheres as the carbon precursor. In this case, the cavitation and carbonization processes occur simultaneously. The as-prepared HCSs were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and Raman spectroscopy. It was found that the cleavage of the ether bond groups (Ar-O-C) and the methylene (-CH₂) in the APF resulted in cavitation and carbonization. The degree of cavitation and carbonization can be adjusted by controlling the thermal treatment temperature and time in air. Furthermore, the sulfur cathode containing HCSs heated at 400 °C exhibited excellent electrochemical performance with an initial discharge capacity of 1006 mA h g^-1 at 0.2 C, and a low capacity decay rate of 0.097% per cycle over 500 cycles at 1 C. The novel one-step AILC strategy will pave a new avenue for the synthesis of hollow carbon spheres and their promising application in different areas.