Interconnected 1D Co3O4 nanowires on reduced graphene oxide for enzymeless H2O2 detection

Enzymeless hydrogen peroxide (H2O2) detection with high sensitivity and excellent selectivity is desirable for clinical diagnosis. Herein, one-dimensional Co3O4 nanowires have been successfully constructed on reduced graphene oxide (rGO) via a simple hydrothermal procedure and subsequent thermal treatment. These Co3O4 nanowires, assembled by small nanoparticles, are interlaced with one another and make a spider web-like structure on rGO. The formation of Co3O4-rGO hybrids is attributed to the structure-directing and anchoring roles of DDA and GO, respectively. The resulting structure possesses abundant active sites, the oriented transmission of electrons, and unimpeded pathways for matter diffusion, which endows the Co3O4-rGO hybrids with excellent electrocatalytic performance. As a result, the obtained Co3O4-rGO hybrids can serve as an efficient electrochemical catalyst for H2O2 oxidation and high sensitivity detection. Under physiological conditions, the oxidation current of H2O2 varies linearly with respect to its concentration from 0.015 to 0.675 mM with a sensitivity of 1.14 mA·mM−1·cm−2 and a low detection limit of 2.4 μM. Furthermore, the low potential (−0.19 V) and the good selectivity make Co3O4-rGO hybrids suitable for monitoring H2O2 generated by liver cancer HepG2 cells. Therefore, it is promising as a non-enzymatic sensor to achieve real-time quantitative detection of H2O2 in biological applications.