Revisiting the StÓ§ber method: Design of nitrogen-doped porous carbon spheres from molecular precursors of different chemical structures

The Stӧber method is revised and used for the preparation of phenolic resin spheres from a series of hetero-atom containing phenol derivatives (such as nitrophenol, aminophenol and halide-substituted phenols), which upon carbonization are converted to heteroatom-doped carbon spheres. The use of 4-amino-3-nitrophenol affords monodispersed carbon spheres with unprecedentedly high nitrogen content of about 11.9 wt%. It is shown that two key factors determine the successful synthesis of monodispersed phenolic resin spheres, namely, the inductive effect of substitution group in phenol derivatives and the orientation effect of the aromatic ring toward electrophilic addition. This study provides some guidelines for selecting phenolic resin precursors with desired molecular structures and functionalities for specific applications.166