Nitrogen-Doped Graphene-Encapsulated Nickel Cobalt Nitride as a Highly Sensitive and Selective Electrode for Glucose...

To explore a natural nonenzymatic electrode catalyst for highly sensitive and selective molecular detection for targeting biomolecules is a very challenging task. Metal nitrides have attracted huge interest as promising electrodes for glucose and hydrogen peroxide (H₂O₂) sensing applications due to their exceptional redox properties, superior electrical conductivity, and superb mechanical strength. However, the deprived electrochemical stability extremely limits the commercialization opportunities. Herein, novel nitrogen-doped graphene-encapsulated nickel cobalt nitride (Ni _xCo_{3- x}N/NG) core-shell nanostructures with a controllable molar ratio of Ni/Co are successfully fabricated and employed as highly sensitive and selective electrodes for glucose and H₂O₂ sensing applications. The highly sensitive and selective properties of the optimized core-shell NiCo₂N/NG electrode are because of the high synergistic effect of the NiCo₂N core and the NG shell, as evidenced by a superior glucose sensing performance with a short response time of <3 s, a wide linear range from 2.008 μM to 7.15 mM, an excellent sensitivity of 1803 μA mM^-1 cm^-2, and a low detection limit of 50 nM (S/N = 3). Furthermore, the core-shell NiCo₂N/NG electrode shows excellent H₂O₂ sensing performances with a short response time of ∼3 s, a wide detection range of 200 nM to 3.4985 mM, a high sensitivity of 2848.73 μA mM^-1 cm^-2, and ultra-low limit detection of 200 nM (S/N = 3). The NiCo₂N/NG sensor can also be employed for glucose and H₂O₂ detection in human blood serum, promising its application toward the determination of glucose and H₂O₂ in real samples.