Controllable preparation of hierarchically core-shell structure NiO/C microspheres for non-enzymatic glucose sensor

Hierarchically core-shell structure NiO/C microspheres were controllably fabricated with a facile hydrothermal method via layer-by-layer assembly. The single-/double-/triple-/quadri-shelled NiO/C microspheres were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX). The results showed that the NiO/C composites are flower-like hierarchically structured microspheres composed of the interconnecting porous nanoplates with the thickness of about 50 nm. Every nanoplate is assembled by NiO nanoparticles with diameter about 10 nm. All the multi-shelled NiO/C microspheres show high electro-catalytic activity toward the oxidation of glucose. The double-shelled NiO/C glucose sensor exhibits the best performance with a much wider linear range of 2 μM-1.279 mM, higher sensitivity of 30.19 mA mM−1 cm−2 and lower detection limit of 2 μM. Importantly, long-term stability and favorable anti-interference were obtained thanks to the hierarchically core-shell structure.