Size-controllable synthesis of carbon spheres with assistance of metal ions

• The size of carbon spheres was successfully controlled through adding metal ions.
• Metal ion strength is proportional to the size and uniformity of the microparticles.
• Homogeneous and heterogeneous adsorption and fusion behavior of nanoparticles resulted in different diameter, texture and surface morphologies of carbon spheres.

This is great interest in tuning diameter of carbonaceous materials for applications in energy storage, templates and separation etc. In this study, different texture and size distribution of carbon spheres were obtained in only one step by hydrothermal carbonization of glucose using metal chlorides, such as NaCl, MgCl2, CaCl2 and FeCl3. Then, structure and chemical composition of the products were characterized by means of SEM, TEM, FTIR and Zetasizer. The combination of these results had allowed us to infer that adding metal ions was more efficient than prolonging hydrothermal treatment in promoting the formation of carbon microspheres. In addition, metal ions strength is proportional to the size of the particles. At last, through investigating the morphology transformation process of the products, a possible growth mechanism was proposed.