The Application Of Cobaltic Compound/Ordered Mesoporous Carbon Composite Materials In Electrochemical Sensor

In recent years, carbon based nanomaterials have been widely used in both analytical and industrial electrochemistry because of their good conductivity and chemical stability. Since one kind of novel carbon materials, i.e. ordered mesoporous carbon(OMC) was synthesized in 1999, intensive attention has been paid on the analytical application of OMC, because of its uniform and tailored pore structure, high specific surface area, large pore volume and chemical inertness. Besides, OMC can be easily prepared via the hard templating strategy with low cost and free from any impurities if the template silica walls are removed. Especially, the utilization of novel mesoporous carbon materials as a catalyst support could enhance the catalyst activity and promote the electron transfer of some analytes. Hence, more and more attention was focused on the electrochemistry and electrocatalysis of the composite materials based on OMC modified electrodes. In this paper, we have investigated the novel OMC was employed as the support for bi-CoPc and Co3O4 catalyst by the first time. This dissertation mainly consists of the following several aspects:Firstly, we obtained the mesoporous silica SBA-15 via Sol-gel process with a triblock copolymer surfactant P123 as template and tetraethyl orthosilicate (TEOS) as organosiloxane precursor. The OMC and porous single crystals Co3O4 can be prepared using mesoporous silica SBA-15 as the hard template and using sucrose and cobaltous nitrate as the precursors, respectively. The obtained mesoporous materials were characterized by XRD, SEM, TEM and N2 adsorption–desorption.Secondly, fabrication of the OMC/Co3O4/Nafion composite modified electrode and its application in electrocatalysis of hydrazine hydrate oxidation are studied. The modified electrode showed a good electrocatalytic response towards hydrazine hydrate and the detection sensitivity was improved dramatically because of the excellent synergistic effect in the composite. The results indicate that OMC/Co3O4/Nafion/GC electrode could be a promising candidate for effectively electrochemical sensors for the detection of hydrazine hydrate due to its very lower detection limit (0.07μM) , fast response (4 s) and wider linear range (4 ~ 320μM).Thirdly, a new ordered mesoporous carbon (OMC) composite modified electrode was fabricated for the first time. Binuclear cobalt phthalocyaninehexasulfonate sodium salt (bi-CoPc) can be adsorbed onto didodecyldimethylammonium bromide (DDAB)/OMC film by ion exchange. UV-vis spectroscopy, scanning electron microscopy (SEM) and electrochemical methods were used to characterize the composite film. The cyclic voltammograms demonstrate that the charge transfer of bi-CoPc is promoted by the presence of OMC. Further study indicated that bi-CoPc/DDAB/OMC film is the excellent electrocatalyst for 4-electron reduction of oxygen in a neutral aqueous solution and for hemoglobin (Hb) reduction at lower concentrations. Additionally, as an amperometric 2-mercaptoethnaol (2-ME) sensor, this modified electrode shows a wider linear range (2.5×10-6 M to 1.4×10-4 M), high sensitivity (16.5μA mM-1) and low detection limit of 0.6μM (S/N=3). All these confirm the fact that the new composite film may have wide potential applications in biofuel cells, biological and environmental sensors.