The enzyme-like activity of Co3O4 nanomaterials has attracted tremendous interest because of their extraordinarily high electron mobility and catalytic activity. However, there are still some controversies on their catalytic performance. In this work, we prepared Co3O4 nanotubes with a large surface area and a uniform nanostructure by electrospinning, and investigated the triple-enzyme mimetic activity of Co3O4 nanotubes: oxidase-like activity, peroxidase-like activity and catalase-like activity. Considering different opinions on the oxidase-like activity of Co3O4 nanoparticles, we investigated the catalytic oxidation performance and the mechanism of Co3O4 nanotubes in detail. The results demonstrated that the Co3O4 nanotubes could effectively catalyze the oxidation of substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the absence of exogenously added H2O2 to produce the blue color product oxTMB. The excellent oxidase-like activities of Co3O4 nanotubes were probably because of the unique nanostructures and large surface area, which may easily adsorb substrates and give more active reaction sites. In addition, based on the oxidase-like activity of Co3O4 nanotubes, a simple and sensitive colorimetric sensor has been developed for the detection of glutathione via the TMB–O2–Co3O4 nanotube system.
