Hexagonal cobalt oxyhydroxide nanoflakes/reduced graphene oxide for hydrogen peroxide detection in biological samples

Abnormal concentration of hydrogen peroxide (H₂O₂) in blood plasma and cells may lead to several diseases. Thus, it is important to develop a selective and sensitive method to monitor H₂O₂. In the present work, a novel nonenzymatic H₂O₂-sensing platform based on cobalt oxyhydroxide (CoOOH)/reduced graphene oxide (RGO) nanocomposite was fabricated. CoOOH nanoflakes were firstly synthesized via soft chemistry routes and then assembled on the surface of RGO. A series of characterizations by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy demonstrated that hexagonal CoOOH nanoflakes were well distributed on the surface of RGO. The nanocomposite exhibited excellent electrochemical performance for H₂O₂ detection. Two linear ranges of 6-200 μM and 200-1500 μM were obtained, and the detection limit was 0.01 μM (signal-to-noise ratio was 3). The good performance was attributed to more exposed catalytic active sites of CoOOH nanoflakes compared with zero-dimensional nanoparticles and outstanding conductivity of RGO as well as their synergistic effect. Moreover, the nanocomposite was used to detect H₂O₂ from human serum and HeLa cells with satisfactory results. Graphical abstract ᅟ.