Two-dimensional Nitrogen-doped Mesoporous Carbon/Graphene Nanocomposites from the Self-assembly of Block Copolymer Micelles in Solution

The self-assembly of block copolymer in solution has proven to be an effective strategy for building up a wide range of nanomaterials with diverse structures and applications.This paper reports a facile self-assembly approach towards two-dimensional (2D)sandwich-like mesoporous nitrogen-doped carbon/reduced graphene oxide nanocomposites (denoted as mNC/rGO) with well-defined large mesopores.The strategy involves the synergistic self-assembly of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) spherical micelles,m-phenylenediamine (mPD) monomers and GO in solution and the subsequent carbonization at 900 ℃.The resultant mNC/rGO nanosheets have an average pore size of 19 nm,a high specific surface of 812 m2·g-1 and a nitrogen content of 2.2 wt％.As an oxygen reduction reaction (ORR) catalyst,the unique structural features render the metal-free nanosheets excellent electrocatalytic performance.In a 0.1 mol·L-1 KOH alkaline medium,mNC/rGO exhibits a four-electron transfer pathway with a high half-wave-potential (E1/2) of +0.77 V versus reversible hydrogen electrode (RHE) and a limiting current density (JL) of 5.2 mA·cm-2,which are well comparable with those of the commercial Pt/C catalysts.