| Porous carbon materials have obtained wide applications in the field of electrochemical analysis due to their many excellent properties. However, the systematic studies about the influences of structure and morphology of porous carbon on its electrochemical sensing properties are still missing. In this thesis, a series of porous carbon materials were individually prepared using CaCO3 nanoparticles, ZnO nanoparticles and metal-organic frameworks Zn-BDC (BDC=1,4-Benzenedicarboxylate) as hard template, and the morphology was tuned via changing the reaction conditions. The influences of preparation parameters on the structure and morphology of porous carbon were discussed. After that, the structure-activity relationship for the electrochemical activity of porous carbon were studied systematically, and the morphology-controlled electrochemical enhancement mechanism of porous carbon was achieved. As a result, several highly-sensitive electrochemical sensing systems were newly developed. The research work of this thesis mainly contains the following five parts:(1) A series of porous carbon materials were prepared using CaCO3 nanoparticles (nano-CaCO3) as the hard template and starch as the carbon precursor. Characterizations of scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS) and chronocoulometry indicated that the morphology, porous structure, specific surface area, electron transfer ability and accumulation efficiency were significantly influenced by the weight ratio of starch and nano-CaCO3. The electrochemical behaviors of four kinds of widely-used food colourants, Sunset yellow, Tartrazine, Ponceau 4R and Allura red, were studied. It is found that their electron transfer ability and accumulation efficiency show great difference on the surface of porous carbon materials that prepared by different ratio of starch and nano-CaCO3. Consequently, the oxidation activity and oxidation signals of colourants also display significant difference. Based on the signal enhancement of porous carbon that tuned by the hard template dosage, a highly-sensitive electrochemical sensing platform was developed. The values of detection limits are 1.4,3.5,2.1 and 1.7μg L-1 for Sunset yellow, Tartrazine, Ponceau 4R and Allura red. Finally, this new sensing platform was used in the analysis of different drink samples. The detected results consist with the values that obtained by high-performance liquid chromatography, and the relative error is below 7.06%.(2) By controlling the 1:1 starch/nano-CaCO3 weight ratio, a kind of porous carbon (PC) was prepared, and then dispersed into N,N-dimethylformamide (DMF). After solvent evaporation, a PC film modified glassy carbon electrode (PC/GCE) was prepared. Compared with the bare GCE, the PC/GCE exhibits remarkable signal enhancement effects toward the oxidation of salvianolic acid B. The enhancement mechanism of porous carbon was examined using chronocoulometry and electrochemical impedance spectroscopy (EIS). As a result, a novel electrochemical method was developed for the detection of salvianolic acid B. The linear range is from 5.0 to 1000.0μg L-1, and the detection limit is 1.16μg L-1(1.61 nM). The method was applied in the sample analysis of different traditional Chinese medicines, and the recovery was in the range of 95.92% to 104.07%.(3) Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials were prepared. It is found that the particle size of ZnO has big impacts on the porous structures, surface area, pore volume and electrochemical activity of the resulting carbon materials. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. We clearly find that the electron transfer ability and accumulation efficiency of AA, DA and UA are improved by different degrees on the surface of prepared porous carbon. Therefore, their oxidation signals also enhance differently, revealing that the signal amplification ability of porous carbon toward the oxidation of AA, DA and UA is closely related to the particle size of hard template. Based on the enhancement mechanism of porous carbon that tuned by hard template size, a highly sensitive electrochemical sensing platform was developed for the simultaneous determination of AA, DA and UA. The detection limits are 3.6 μM,15 nM and 10 nM for AA, DA and UA. It was employed in the blood serum sample analysis, and the results was accurate.(4) Using ZnO nanoparticles with diameter of 30 nm as the hard template and starch as carbon precursor, a kind of porous carbon denoted as PC-30 was prepared under the 1:1 weight ratio of starch and ZnO particles. By means of dispersion and solvent evaporation, a new electrochemical sensor was constructed for ractopamine. The electrochemical behaviors of ractopamine indcate that the prepared PC-30 possesses remarkable enhancement effects, and greatly increases the the oxidation signals of ractopamine. In addition, the signal enhancement mechanism of PC-30 and the signal response discipline of ractopamine were deeply discussed. As a result, a sensitive, rapid and sensitive electrochemical method was developed for the determination of ractopamine, with detection limits of 4.39 nM. The newly developed method was used for the analysis of pork samples, and the recovery was over the range from 92.7% to 106.2%.(5) Using metal-organic frameworks Zn-BDC as hard template and P-cyclodextrin as the carbon precursor, a kind of three-dimensional porous carbon was prepared. Experiments of SEM, TEM, Nitrogen adsorption-desorption isotherms were used to characterize the pore structure, morphology and pore size distribution of the prepared carbon materials. It is that the resulting porous carbon owns three-dimensional connected pore structure, and simultaneously contains macropores, mesopores and micropores. After that, the obtained porous carbon was dispersed into DMF, and used to modify the surface of GCE. It is found that the modification of porous carbon enahnces the active response area and electron transfer ability of GCE. Moreover, the oxidation signals of hydroquinone and catechol are greatly improved on the surface of porous carbon-modified GCE. Based on the remarkable enhancement effects of three-dimensional porous carbon, a novel electrochemical system was developed for the simultaneous determination of hydroquinone and catechol, with detection limits of 4.5 nM and 9.9 nM. |
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