N-doped hollow mesoporous carbon spheres prepared by polybenzoxazines precursor for energy storage

A co-assembly approach has been developed to controllably fabricate N-doped hollow mesoporous carbon spheres (N-HMCS) with different morphologies. Cetyl-3-methyl ammonium bromide and tetraethyl orthosilicate (TEOS) are applied to co-assemble with polybenzoxazines (phenol/formaldehyde/ethylenediamine (PB) resin) through electrostatic interaction. The utilization of ethylenediamine (EDA) is to introduce nitrogen into N-HMCS and catalyze hydrolysis of the silica precursor and polymerization of PB. The increasing amount of EDA leads to different morphologies of N-HMCS, changing from irregular particle aggregates to hollow spheres with increasing in diameter by controlling the hydrolysis rate of TEOS. In addition, pre-polymerization of phenol/formaldehyde oligomer is another key factor for the formation of N-HMCS, which is proved by the irregular porous particles obtained by direct assembly of phenol, formaldehyde and EDA. The different morphologies in N-HMCS show variable electrochemical performance when using as electrode materials in supercapacitor. Typically, N-HMCS with regular spherical morphology, small diameter and thin shell shows better performance, proving its excellent prospects in energy storage. (C) 2020 Elsevier Ltd. All rights reserved.