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.