| Graphene, a flat monolayer of sp2-bonded carbon atoms tightly packed into a two-dimensional honeycomb lattice, is considered as the thinnest material in the universe, and offers biocompatibility, high carrier mobility and capacity, high electron transfer rates, robustness, flexibility, a high degree of opacity, and high surface-to-volume ratios. More interests are attracted in the fundamental standpoint as well as for practical applications due to its excellent electronic, electrochemical, and thermal properties. The unique properties of graphene, for instance high surface area-to-volume ratio, fast electron transferring rate and good biocompatibility, suggest that it has the ability to be incorporated in a comprehensive applications, including composites, electronics, new energy and medical therapeutics. In this paper, graphene, 3D grapheme (3D-GR) and metal@semiconductor core-shell nanomaterials had been synthetized. Electrochemical sensors for detection of small biomolecules and bisphenol substances were proposed based on grapheme or 3D graphene-metal@semiconductor core-shell nanocomposites modified glassy carbon electrode. Therefore, this paper focuses on the following works:(1) A novel ascorbic acid sensor was proposed based on graphene and gold-zinc oxide core-shell nanomaterial modified glassy carbon electrode (GCE). The graphene and gold-zinc oxide core-shell nanomaterial were synthetized by modified Hummer method and hydrothermal synthesis method, respectively, and characterized by transmission electron microscope (TEM) and energy dispersive X-ray spectroscopy (EDS). The AA sensor exhibits good performance in terms of the electrocatalytic oxidation of AA at 0.13 V potential. The modified electrode shows a good linear dependence on ascorbic acid concentration in the range of 0.10 μM to 600 μM with a sensitivity of 24.12 μA·mM-1. The detection limit is estimated to be 0.039 μM (S/N= 3). Furthermore, the AA sensor exhibits freedom of interference from other co-existing electroactive species and excellent performance in the actual samples. (2) The electrochemical sensor for simultaneously detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA) was developed based on 3D-GR and gold-copper oxide core-shell nanocomposites modified glassy carbon electrode. The 3D-GR and egg-yolk formula gold-copper oxide core-shell nanomaterial were characterized by TEM, EDS and SEM. Under the optimal experimental conditions, the sensor exhibits good performance in terms of the electrocatalytic oxidation of ascorbic acid, dopamine and uric acid. The sensor shows a good linear dependence on AA, DA and UA concentration in the range of 5 μM to 1000 μM,2 μM to 1100 μM and 3 μM to 1100 μM with a detection limit of 1.40 μM,0.42 μM and 0.53 μM (S/N= 3), respectively. In addition, the modified sensor shows good reproducibility, stability anti-interference, and can be applied in real sample ssuccessfully.(3) An electrochemical sensing platform for simultaneously detection of hydroquinone and resorcinol based on 3D-GR and carbon spheres-copper oxide core-shell nanomaterial modified glassy carbon electrode. The 3D-GR and carbon spheres-copper oxide core-shell nanomaterial were characterized by EDS and SEM. The electrochemical behavior of 3D-GR/CNPs@CuO nanocomposites in simultaneous determination of hydroquinone and resorcinol was studied by cyclic voltammetry and differential pulse voltammetry. A pair of well-defined redox peaks are observed in CV, the peak potential separation is large enough to separate hydroquinone and resorcinol. The oxidation peak currents of hydroquinone and resorcinol were linear over the range of 0.5～1200μM and 10～800μM with the detection limits of 0.16μM for hydroquinone and 1.69μM for resorcinol, respectively. In addition, the sensor exhibits excellent peculiarities, such as high sensitivity, wide linear range, lower detection limit and fast response time, and was successfully applied in real water samples. |
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