Preparation of spinel nickel-cobalt oxide nanowrinkles/reduced graphene oxide hybrid for nonenzymatic glucose detection at physiological level

- Spinel type NiCo2O4 nanowrinkles-rGO hybrid is prepared for glucose sensing.
- Both spinel NiCo2O4 and rGO contribute to enhanced catalysis of the hybrid.
- The hybrid shows much higher catalysis than that of NiO, Co3O4, or NiCo2O4.
- The hybrid based sensor could achieve glucose sensing at physiological level.

Nickel-cobalt oxide nanowrinkles with spinel-type crystal structure supported on reduced graphene oxide (NiCo2O4 NWs-rGO) was prepared to develop a sensitive and stable nonenzymatic glucose sensor. The NiCo2O4 NWs-rGO hybrid were prepared by a facile one-pot hydrothermal reaction, and sequential calcination in air. The morphology, composition and crystal structure of the NiCo2O4 NWs-rGO hybrid were characterized by scanning electron microscope, transmission electron microscope, selected area electron diffraction, and energy-dispersive spectroscopy. The electrochemical behavior of the hybrid and its catalytic activity towards glucose oxidation were investigated by several electrochemical methods. Compared with single component NiO or Co3O4, spinel type NiCo2O4 NWs displayed higher catalysis towards glucose oxidation. Further integration of NiCo2O4 with graphene could reduce the overpotential and enhance the catalytic current due to the improved conductivity and dispersity of NiCo2O4. The NiCo2O4 NWs-rGO based glucose sensor showed a wide linear range of 0.005-8.6 mM, a low detection limit of 2 μM (S/N = 3), and an improved stability. A satisfactory recovery was also obtained for glucose detection in human serum at physiological level. Our results indicate rationally combine spinel type mixed metal oxide with graphene is a good alternative to fabricate advanced metal oxide based electrochemical sensors.