Electrochemistry And Electrocatalysis Of Ordered Mesoporous Carbon Composite Materials

The ordered mesoporous carbon (OMC) which was first synthesized in 1999 is particularly promising because of the fact that SBA-15 template is inexpensive and easy to synthesize. And OMC also exhibits extremely high surface area and well defined pore size as well as high thermal stability, flexible framework composition and chemical inertness, which make OMC potential novel materials for investigating the electrochemical behavior of the substances. Contrary to most porous silica-based materials (for example, SBA-15) that are electronic insulators, the mesoporous carbons are intrinsically conductors. So we have investigated the electrochemistry and electrocatalysis of OMC and the composite materials based on it. This dissertation mainly consists of the following several aspects:(1) In this work, we have developed a convenient and efficient method for the functionalization of OMC using polyoxometalate H6P2Mo18O62·xH2O (P2Mo18). By the method, glassy carbon (GC) electrode modified with P2Mo18 which was immobilized on the channel surface of OMC was prepared and characterized for the first time. Fourier transform infrared spectroscopy (FTIR), Nitrogen adsorption–desorption isotherm and X-ray diffraction (XRD) were employed to give insight into the intermolecular interaction between OMC and P2Mo18. The Cyclic voltammetry (CV) and amperometry studies demonstrated that P2Mo18/OMC/GC electrode has high stability, fast response and good electrocatalytic activity for the reduction of nitrite, which makes P2Mo18/OMC/GC electrode potential candidates for the efficient electrochemical sensors for nitrite detection.(2) We investigated the electrochemical mechanisms for CySH oxidation at OMC/GC electrode with different pH values. OMC/GC electrode showed excellent electrocatalytic effect toward cysteine (CySH) oxidation. The voltammetric studies showed the electro-oxidation of CySH undergoes consecutive three steps instead of two when pH below 5.00. And we conclude only CySH2+ (H3A+) and CyS- (HA-) are the electroactive substances and should be responsible for the electro-oxidation of CySH. On the other hand, as a CySH sensor based on OMC/GC electrode, a remarkably low detection limit (2.0 nmol L-1, which is the lowest value ever reported for direct CySH determination on the electrodes) at pH 2.00, which make OMC/GC electrode a promising candidate for sensitive electrochemical sensors for CySH detection.(3) A stable OMC was obtained by dispersing the OMC in a solution of Nafion. By coating the suspension onto the GC electrode, Nafion-OMC/GC electrode exhibiting strong and stable electrocatalytic response toward epinephrine (EP) was prepared and characterized Furthermore, the EP amperometric response of the Nafion-OMC/GC electrode at pH 4.1 is extremely stable, with 99% of the initial activity remaining after 120 min stirring of 2.00×10-4 mol L-1 EP solutions (compared to 32% at GC surface). The anodic peaks of EP and ascorbic acid (AA) were separated successfully (by ca. 144–270 mV) in the pH range of 2.0 to 10.0, which makes the modified electrode potential for selective determination of EP in the presence of AA at a broad pH range.