Fe3O4 nanoparticles entrapped in the inner surfaces of N-doped carbon microtubes with enhanced biomimetic activity.

Tubular structured composites have attracted great interest in catalysis research owing to their void-confinement effects. In this work, we synthesized a pair of hollow N-doped carbon microtubes (NCMTs) with Fe3O4 nanoparticles (NPs) encapsulated inside NCMTs (Fe3O4@NCMTs) and supported outside NCMTs (NCMTs@Fe3O4) while keeping other structural features the same. The impact of structural effects on the catalytic activities was investigated by comparing a pair of hollow-structured nanocomposites. It was found that the Fe3O4@NCMTs possessed a higher peroxidase-like activity when compared with NCMTs@Fe3O4, demonstrating structural superiority of Fe3O4@NCMTs. Based on the excellent peroxidase-like catalytic activity and stability of Fe3O4@NCMTs, an ultra-sensitive colorimetric method was developed for the detection of H2O2 and GSH with detection limits of 0.15 μM and 0.49 μM, respectively, which has potential application value in biological sciences and biotechnology.