## 5 Graphene-Based Electrode for Non-Enzymatic Glucose Biosensor
Similar work was prepared by [PERSON] et al. [147], the article shows a functionalized graphene oxide (fGO) decorated with magnetite (Fe\({}_{3}\)O\({}_{4}\)) nanoparticles and PANI for the non-enzymatic glucose sensor. The electrochemical properties of a fGO-Fe\({}_{3}\)O\({}_{4}\)-PANI nanocomposite were measured using CV techniques. The fGO-Fe\({}_{3}\)O\({}_{4}\)-PANI nanocomposite modified electrode shows a very good oxidation result towards glucose with a linear range of 0.05-5 mM and a limit of detection 0.01 uM by taking advantage of the improvement of the electrocatalytic activity of N-doped graphene [148]. [PERSON] et al. [149] demonstrated a nitrogen-doped graphene non-enzymatic glucose sensor which detects a biological PH value. The team shows a limit of detection of 0.13 uM, sensitivity of 774.23 uA mM\({}^{-1}\) cm\({}^{-2}\), and linear range of glucose concentration 0.13-14 mM @ pH 13, while a superior sensitivity of 122.336 uA mM\({}^{-1}\) cm\({}^{-2}\), the detection limit of 14.52 uM, and fast linear range of 14.52 -10 mM @ biological pH (7.4) value. [PERSON] et al. [150] successfully fabricated a non-enzymatic glucose detection using the nanoneedle-like copper oxide on an N-doped reduced graphene oxide. The constructed sensor demonstrates an increasing contacting area between the  
Figure 10: **(a)** The CV response of the Ag-NW/RGO hybrid 3D towards glucose oxidation at different concentrations of glucose. **(b)** The amperometric responses of rGO-only 3D NS for comparison. **(c)** The Ag-NW/RGO hybrid 3D NSs amperometric response at each additional 1 mM of glucose. **(d)** The linearity detection between the glucose concentration and current for rGO-only 3D NS and Ag-NW/RGO hybrid 3D NSs. Source: [[https://www.sciencedirect.com/science/article/pii/S221137971931040X#s0035](https://www.sciencedirect.com/science/article/pii/S221137971931040X#s0035)]([https://www.sciencedirect.com/science/article/pii/S221137971931040X#s0035](https://www.sciencedirect.com/science/article/pii/S221137971931040X#s0035)). electrode and electrolyte. The result investigated a linear range of 0.5-639 uM and a low detection limit of 0.01 uM. Graphene with Ni\({}_{2}\)P nanoparticles could be used for glucose detection. [PERSON] et al. [151] showed the enhancement of the electrochemical properties of the non-enzymatic glucous sensor using porous Ni\({}_{2}\)P/graphene composites. This metal-organic framework shows a very good electrocatalytic activity towards glucose electrooxidation. The work was characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and X-ray photoelectron spectroscopy (XPS), while the electrochemical properties were characterized by cyclic voltammetry (CV) and amperometric. The Ni-MOF-74 nanocrystals were prepared using PVP as a stabilizer while the Ni\({}_{2}\)P/G composite structure was obtained using sodium hypophosphite. The sensor shows a linear range between 5-1.4 mM with a detection limit of 0.44 uM. [PERSON] et al. [152] created a non-enzymatic sensor for glucose detection in the human serum based on a three-dimensional graphene foam decorated with Cu-\(x\)Cu\({}_{2}\)O nanoparticles. The electrochemical properties of Cu-based nanoparticle concentrations were measured using cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. The Cu-Cu\({}_{2}\)O NPs@3 DG foam shows a linear range of 0.8-10 mM, a high sensitivity of 230.86 uA mM\({}^{-1}\) cm\({}^{-2}\), and a detection limit of 16 uM. The sensor shows a new way for the inexpensive non-enzymatic glucose sensor. More work in graphene-based electrodes for non-enzymatic glucose sensors have been summarized, as shown in Table 3. The table reviews the metal/graphene composites in non-enzymatic glucose sensors such as Au/GO, Pd/GO, Pt/GO, etc.