In situ controllable growth of CoFe2O4 ferrite nanocubes on graphene for colorimetric detection of hydrogen peroxide

A facile method is proposed for the synthesis of cubic CoFe2O4 ferrite-reduced graphene oxide nanocomposite sheets (rGO-CFs), using poly(N-vinyl-2-pyrrolidone) as the reductant and stabilizer. The rGO-CFs functioned as efficient peroxidase mimetics and were successfully applied for colorimetric assay. The morphology and composition of the rGO-CFs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Significantly, the peroxidase-like activity of the rGO-CFs followed typical Michaelis-Menten kinetics and showed a good affinity to 3,3,5,5-tetramethyl benzidine. Under optimum conditions, the colorimetric assay showed a lower detection limit (S/N = 3) of 0.3 mu M when compared with that of other nanoparticle based colorimetric assays. Furthermore, the cubic nanostructured rGO-CFs exhibited better stability than horseradish peroxidase when they were exposed to solutions with different solvents and temperatures. These excellent properties made the cubic nanostructured rGO-CFs an ideal candidate for a wide range of potential applications as peroxidase mimetics.