| Nowdays, nano materials, especially carbon-based nano materials, have been widely used in electrochemical sensing fields due to their special physical and chemical properties. Carbon-based nano materials mainly include fullerene and carbon particles with zero dimensions, carbon nanotubes and nanofibers with one dimensions, as well as two dimensional graphene. Recently, researchers have found a new kind of zero dimensional carbon-based nanomaterial in purification of carbon nanotubes, and it will be named as carbon nanodots. Similar to other metal semiconductor quantum dots, nano carbon dots has also good fluorescence properties. Moreover, nano carbon dots have more excellent properties such as water solubility, low toxicity, good biocompatibility, rich surface activity, as well as the excellent performance of the electronic teaching. Benefit from these excellent properties, nano carbon dots have been attached great importance in many fields including photocatalysis, biological imaging and optoelectronics. In the analytical science, the main use of the nano carbon dots is to design various optical sensors due to its excellent fluorescence activity. In the field of electrochemical sensing, nano carbon dots will have broad application prospects due to its unique physical and chemical properties. However, it is difficult to directly attached nano carbon dots on the base electrode surface due to its maller size and more hydrophilic. Therefore, the main use of nano carbon dots in electrochemical sensing is to improve the electrochemical activity by fabricating nano cabon dots-based composites with other functional materials. Based on this, we firstly prepared and characterized nano carbon dots by using hydrothermal method and photolithography. Then, five kinds of chemically modified electrode with nano carbon dots-based composite materials have been fabricated. Furthermore, the electrocatalytical activity and analytical performance of these modified electrodes for dopamine, hydrogen peroxide, bisphenol A and glucose have been investigated carefully. The research work is important in expanding the application of nano carbon in electrochemical sensing, improving the analytical performance of the related substances, as well as enriching the research content of chemically modified electrode.This thesis mainly content is as follows:1. Nano carbon dots have been prepared by using hydrothermal method with glucose as a carbon source. Then an overoxidized polypyrrole and nano carbon dots composites modified electrode has been fabricated by direct electrochemical methods. The electrochemical behavior of dopamine(DA) on this modified electrode has been investigated by cyclic voltammatry(CV) and different pulse voltammetry(DPV). The results show that this modified electrode exhibited high electrocatalytic activity and good selectivity for the oxidation of DA. Under the optimal conditions, the liner calibration curves by DPV are 5.0 × 10–8 mol·L–1 ~ 3.0 × 10–5 mol·L–1 with the detection limits of 1.0 × 10–8 mol·L–1(3sb).2. Nano carbon dots have been firstly prepared by using hydrothermal method with glucose as a carbon source. Then nano carbon dots and silver nano particles composites(Ag NCs/CNs) have been fabricated by in-situ chemical reduction method. Based on this, a Ag NCs/CNs modified electrode has also been fabricated. The electrochemical behavior of hydrogen peroxide on this modified electrode has been investigated carefully. The results show that this modified electrode exhibited high electrocatalytic activity for the reduction of hydrogen peroxide. Under the optimal conditions, the liner calibration curves by amperometry is 1.4 × 10-5 ~ 3.4 × 10-2 mol·L-1 with the detection limits of 5.0 × 10-6 mol·L-1(3sb).3. Nano carbon dots have been firstly prepared by using hydrothermal method with glucose as a carbon source. Then nano carbon dots and cerium oxide composites(Ce O2/CNs) have been fabricated by in-situ chemical precipitation method. Based on this, a Ce O2/CNs modified electrode has also been fabricated. The electrochemical behavior of bisphenol A on this modified electrode has been investigated carefully. The results show that this modified electrode exhibited high electrocatalytic activity for the oxidation of bisphenol A. Under the optimal conditions, the liner calibration curves by amperometry is 5.0 × 10–9 ~ 1.0 × 10–5 mol·L-1 with the detection limits of 1.0 × 10–9 mol·L–1(3sb). Compared to other method, this modified electrode exhibit broad linear range and low detection limits.4. The copper oxide and nano carbon dots hybrid(Cu2O/CNs) has been prepared by using hydrothermal method from a solution containing glucose and cupric nitrate. Based on this, a Cu2O/CNs modified electrode has also been fabricated. Benefit from the synergistic effect of copper oxide and nano carbon dots, this composite material show very high electrocatalytic activity for the electrochemical oxidation of glucose. Under the optimal conditions, the liner calibration curves by amperometry is 2.0 × 10-7 ~ 2.3 × 10-3 mol·L-1 with the sensitivity of 430.6 μA·m M-1. Moreover, this modified electrode also exhibits good selectivity for the determination of glucose in serum samples.5. Nano carbon dots have been firstly prepared by using photolithography method with graphene oxide(GO) as a carbon source. Then, an overoxidized polypyrrole and nano carbon dots composites film(CNs/OPPy) modified electrode has been fabricated by direct electrochemical methods. Lastly, this CNs/OPPy film modified electrode has been used as a platform for the prpeparation of nikel and iron hybrid hexacyanoferrates modified electrode(Ni-Fe HCF/CNs/OPPy/CCE). The electrochemical behavior of hydrogen peroxide on this modified electrode has been investigated carefully. The results show that this modified electrode exhibited high electrocatalytic activity for the reduction of hydrogen peroxide. Under the optimal conditions, the liner calibration curves by amperometry is 3.0 × 10–6 ~ 4.7 × 10–3 mol·L–1 with the detection limits of 5.0 × 10–7 mol·L–1(3sb). |
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