Fe 3 O 4 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 Fe 3 O 4 nanoparticles (NPs) encapsulated inside NCMTs (Fe 3 O 4 @NCMTs) and supported outside NCMTs (NCMTs@Fe 3 O 4 ) 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 Fe 3 O 4 @NCMTs possessed a higher peroxidase-like activity when compared with NCMTs@Fe 3 O 4 , demonstrating structural superiority of Fe 3 O 4 @NCMTs. Based on the excellent peroxidase-like catalytic activity and stability of Fe 3 O 4 @NCMTs, an ultra-sensitive colorimetric method was developed for the detection of H 2 O 2 and GSH with detection limits of 0.15 μM and 0.49 μM, respectively, which has potential application value in biological sciences and biotechnology.