In Situ Two-Step Preparation of 3D NiCo-BTC MOFs on a Glassy Carbon Electrode and a Graphitic Screen Printed Electrode as Nonenzymatic Glucose-Sensing Platforms

In the present study, a rational two-step strategy is employed for the green, fast, very simple, and highly controllable synthesis of the bimetallic nickel–cobalt-based metal–organic frameworks (MOFs) on glassy carbon substrates by in situ transformation of nickel–cobalt-layered double hydroxide nanosheet (NiCo-LDHs NSs) intermediates into nickel–cobalt–benzene tricarboxylic acid MOFs (E-NiCo-BTC MOFs). The structural characteristics of the electrode materials in each step were investigated via Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, elemental mapping, field emission scanning electron microscopy, and transmittance electron microscopy. In addition, the electrocatalytic behavior of the E-NiCo-BTC/GCE as a nonenzymatic sensing platform toward glucose electro-oxidation was evaluated via cyclic voltammetry, amperometry, and electrochemical impedance spectroscopy techniques. The as-prepared sensing platform shows two linear dynamic ranges of 0.001–1.78 mM with a sensitivity of 1789 μA mM–1 cm–2 and 1.78–5.03 mM with a sensitivity of 1436 μA mM–1 cm–2 together with acceptable selectivity against interfering species, high poisoning resistance against chloride ions, and high repeatability and reproducibility of glucose electro-oxidation responses. The value of the detection limit based on a signal to noise ratio of 3 (S/N = 3) was calculated to be 0.187 μM. Moreover, the electrochemical responses of E-NiCo-BTC/GCE were compared to those of modified electrodes via hydrothermal-based NiCo-BTC MOFs and corresponding monometallic based modified electrodes obtained via an in situ method. Finally, in order to investigate the commercialization capability and to develop the proposed sensor from lab-to-market, the same in situ two-step strategy with some variations was used to modify the graphitic screen-printed electrode. This sensing platform showed acceptable responses toward glucose electro-oxidation with a low fouling effect of the modifier film over a wide range of glucose concentrations (0.0–5.7 mM) and an ignorable real sample matrix effect on the sensor performance as well as good sensitivity (230.5 μA mM–1 cm–2) and selectivity, which verify the ability of the proposed method for designing accurate and credible low-cost and on-site sensing platforms for practical applications.