Fig. 3
a Three CVs in the image: the red curve showed the CV of bare ITO; the orange and green curves were the CVs of α-NiS films at different annealing temperatures (300 and 500 °C). Inset: CV of bare ITO/glass. b CV of nano-NiS/ITO in 0.1 M NaOH with different concentrations of glucose: (α) 0 μM, (β) 2 μM, (γ) 7 μM, (δ) 10 μM, (ε) 15 μM, (ζ) 20 μM, (η) 30 μM, and (θ) 35 μM. Inset: top left—plot of oxidation peak current against glucose concentration; bottom—CVs of Ni film and Ni nanosheet film. c The α-NiS nanosphere film was assessed by amperometry in 0.1 M NaOH with different concentrations of glucose: (α) 1 μM, (β) 2 μM, (γ) 7 μM, (δ) 10 μM, (ε) 15 μM, (ζ) 20 μM, (η) 22 μM, (θ) 25 μM, (ι) 30 μM, and (κ) 35 μM. Inset: top left—plot of the current responses against glucose concentrations; bottom—chronoamperometric response of NiS/ITO in 0.1 M NaOH with 2 μM glucose and in the presence of 2 μM dopamine, uric acid, and lactic acid at an applied potential of 0.6 V DC. d Nyquist plots of the nickel nanosheet film, α-NiS nanosphere film, and α-NiS films at different annealing temperature (300 and 500 °C) in 0.1 M KCl containing 1.5 mM Fe(CN)63−/4−. e CV of nano-NiS/ITO in Krebs with different concentrations of glucose: (α) 0 μM and (β) 20 μM. Inset: top left—CV of bare ITO/glass. f The α-NiS nanosphere film was assessed by amperometry in Krebs buffer with different concentrations of glucose: (α) 0 μM, (β) 10 μM, (γ) 20 μM, (δ) 30 μM, and (ε) 40 μM. Inset: top—plot of the current responses against glucose concentrations