Ni/NiO multivalent system encapsulated in nitrogen-doped graphene realizing efficient activation for non-enzymatic glucose sensing

Nowadays, given the booming demand of blood sugar control from the soaring number of diabetes patients and the insufficient stability of costly enzyme-based glucose sensors in clinic, the development of enzyme-free sensors has been drawing tremendous attraction. Herein, we fabricated a unique structure of Ni/NiO hybrid nanoparticles with mixed-valence states encapsulated in and cross-linked by nitrogen-doped graphene via a facile Ni-MOF-annealing approach and developed its notable feature in efficiently non-enzymatic glucose sensing. The microstructure and valence states, proved vital to the electrochemical activity and sensing performance, were simultaneously regulated by the annealing temperature. The optimized sample obtained at 400 °C displays the superior activation behavior and best glucose sensing performance, offering a high sensitivity of 3.2518 mA mM −1  cm −2 , a wide linear range (0.001–3.568 mM), a low detection limit (0.032 μM, S/N = 3) as well as excellent selectivity, good reproducibility, long-term stability, and satisfactory applicability in real sample. By further investigation of the electrochemical kinetics mechanism, the synergistic effect of multivalent system and well-organized microstructure was proved beneficial for charge transfer, activation of reaction sites, and elimination of electrode polarization as well, thus providing a promising strategy in designing non-enzymatic biosensor platform for glucose detection in actual diagnosis.