Preparation Of Three-dimensional Carbon-based Electrodes Composites And Its Application In Electrochemical Sensing

Electrochemical sensor has good selectivity, high sensitivity, simple instrument etc, is an ideal analytical tools to get complex system information fastly and directly. They have a wide range of applications in biotechnology, environmental monitoring, analysis of pesticide residues, food industry, pharmaceutical industry and other fields. The using of novel nanomaterials in electrochemical sensor can increase the sensor sensitivity and decrease the detection limit significantly. In recent years, some metals, metal oxides, metal-polymer nanomaterials have been widely applied in nonenzymes electrochemical sensing field. However, the directly using of nanomaterials will easily occurred accumulation, not only damage the excellent properties of nanomaterials of nanoscale, but also hindered the active surface of nanomaterials, which greatly impact the electrochemical activity of the electrode materials.In this work, nanomaterials directly growth in surface of carbon substrate material through electrochemical method, the resultant nanocomposites electrode materials can also be directly used for detection without cumbersome immobilized procedure. Compared with the nanomaterials, the nanocomposites electrode materials exhibit high capacity and good dispersivity of nanomaterials, it can effectively release the electrochemical properties of nanocomposites electrode materials. At the same time, the nanocomposites electrode materials could avoid the modified steps, the use of polymer binder, reduce the experimental error caused by artificial operation. But above all, the direct growth of the nanomaterials on the substrate surface is conducive to construct orderly array, three dimensional nanomaterials. In this work, we attempt to construct the nanocomposites electrode materials based on carbon substrate and actived nanometerials. A synergistic effect could be expected and the electrochemical performance could be improved in the nanocomposite. The main work is as follows:（1） A novel nonenzymatic glucose sensor was developed by electrodepositing copper-cobalt（Cu-Co） nanostructures on persimmon-derived carbon（PC） nanocomposites. The electrochemical behaviors and electrocatalytic performances of this sensor towards oxidation of glucose were evaluated by cyclic voltammograms, chronoamperometry and amperometric method. Compared to the sensors based on monometal Cu or Co, the sensor based on bimetal Cu-Co exhibits good electrocatalytic activity towards oxidation of glucose. The effects of electrodeposition potential and the ratio of Cu²⁺ and Co²⁺ in an electrodeposition solution on the electrocatalytic performance of the Cu-Co/PC were explored in detail. The best catalytic activity towards oxidation of glucose can be achieved under an optimized condition: electrodepositing potential of-1.2 V and the Cu²⁺/Co²⁺ molar ratio of 1:20. The catalytic current density is linear to the glucose concentration in the range of 0.002 m M-2.73 mM（R=0.9977） with a sensitivity of 2.21 mA cm^-2 mM^-1, and a detection limit of 0.7 μM.（2） A flexible nanocomposite of cobalt hexacyanoferrate（CoHCF） and commercial carbon cloth（CC） was prepared by using a facile electrodepositing CoHCF on flexible CC surface. As a kind of flexible integrated electrode without polymer binders, the flexible CC-CoHCF nanocomposites were directly used for nonenzymatic H₂O₂ sensing. It was found that CoHCF nanoparticles（about 100 nm） uniformly deposited on CC surface. Electrochemical experiments demonstrated that the flexible CC-CoHCF nanocomposite electrode exhibited good electrocatalytic activity towards the oxidation of H₂O₂. Based on the amperometric experiments, the proposed nonenzymatic sensor showed a linear response to the H₂O₂ detection in the range of 0.002-9.04 mM with a detection limit of 0.7 μM, which was superior to most of previous results. Such good result renders it promising candidate for routine testing.（3） A novel nonenzymatic glucose sensor was prepared based on Au nanoparticles/polyaniline（PANI）/CC nanocomposites electrode materials. The PANI nanowire arrays/CC nanocomposite was synthesized by electropolymerization method, Au nanoparticles were constructed on Au/PANI/CC by electrodeposition. The electrochemical and electrocatalytic behaviors of the Au/PANI/CC towards glucose oxidation were evaluated by cyclic voltammograms, and it showed high catalytic activity towards the oxidation of glucose with a wide linear range of 0.1 to 12.0 mM, high sensitivity of 150 μA cm^-2 mM^-1 and low detection limit of 0.01 mM（S/N=3）.