Synthesis And Application Of Novel Porous Carbon-based Composites In Energy And Environment

Porous carbon is a class of advanced materials and is considered as "the next generation of mesoporous materials". Porous carbon possesses several fascinating properties including high surface areas, large pore volumes, well- defined pore size, high thermal stability, high mechanism and chemical stability, and good electric conductivity, showing promising potential applications for adsorption, separation, delivery of biomolecules, catalysis, electrochemistry, and so on. The mesoporous carbons are intrinsically conductors and easy to synthesize. Hence, more and more attention was focused on the catalysis, electrochemistry and electrocatalysis of OMC and the composite materials as advanced electrode materials. This thesis presents a systematic study regarding the following well-connected aspects of mesoporous carbon, including synthetic method for large-scale production, exploring of new synthetic methods, controlling of unique morphology, manipulating of framework functionality, and their applications in carbon dioxide utilization and lithium ion batteries.The thesisis composed of seven chapters. The first chapter is a detailed review on the current situation of environment pollution and energy crisis, the development and research status of mesoporous carbons.Chapter 2 described the preparation process of a new type of graphitic ordered mesoporous carbon and TiO2 loaded graphitic ordered mesoporous carbon composite used for photocatalytic reduction of carbon dioxide with water to organic fuels. We introduce a novel method to synthesize graphitic ordered mesoporous carbon materials by a simple one-step solid-liquid grinding/templating route using SBA-15 as a hard template. Impacts of different calcination temperature and carbon precursor on the degree of graphitization are discussed. A representative graphitic ordered mesoporous carbon derived from soybean oil (SBO) was synthesized by carbonizing the SBO/SBA-15 mixture at different calcination temperature. From the wide-angle XRD patterns of SBO derived carbon replicas after the carbonization of SBO/SBA-15 composites at 600 ℃, it can be seen that the characteristic peaks for graphite showing (002) and (100) diffractions are prominent for samples taken after pyrolysis. As the pyrolysis temperatures increase, the diffractions corresponding to the graphite phase are more pronounced, suggesting a higher degree of graphitization. The composite shows a stacking of the distinct discoid graphene sheets oriented perpendicular to the direction of the rods after the carbonization of SBO/SBA-15 composites at 900 ℃. Besides the soybean oil, other seed fats from colza, peanut, sunflower seed, maize, etc., can also be used as liquid carbon precursors to synthesize mesoporous carbon materials with a graphitic framework. It should be noted that these graphitic ordered mesoporous carbons derived from seed fat have a high surface area (560-680 m2 g-1) and uniform accessible mesopores, making them ideal candidates for many potential applications, such as for use as catalyst/photocatalyst supports or electrode materials. When used as catalyst, the TiO2 supported on graphitic mesoporous carbon as photocatalysts (TiO2/SBO-700 and TiO2/SBO-900) exhibit much higher photocatalytic reactivity than the other catalysts, and the activity of TiO2/SBO-900 is also slightly better than that of TiO2/SBO-700 with CO and CH4, yield of 61.4 and 10.5 μmol g-1 cat., respectively, under 8 h of UV irradiation. This result suggests that the photocatalytic activity of the composite catalysts in this reaction is greatly affected by the degree of graphitization of mesoporous carbon supports.Chapter 3 described the preparation process of a new type of Cu doped graphitic ordered mesoporous carbon supported TiO2 used for photocatalytic reduction of carbon dioxide with water to organic fuels under simulated solar irradiation. We introduce a novel method to synthesize graphitic ordered mesoporous carbon materials by a simple one-step solid-liquid grinding/templating route using SBA-15, copper nitrate and seed fat as a hard template, copper precursors, caron precursors, respectively.Chapter 4 described the preparation process of Fe/y-Fe2O3 doped graphitic ordered mesoporous carbon supported TiO2 (Fe-TiO2-GMC, γ-Fe2O3-TiO2-GMC) used for photocatalytic reduction of carbon dioxide with water to organic fuels under simulated solar irradiation. It can be observed that the Fe-TiO2-GMC (CH4:8.9 micromol g-1 cat.) and γ-Fe2O3-TiO2-GMC composite (CH4:8.8 micromol g-1 cat.) exhibited much higher photocatalytic activity than that of P25 titania (CH4:3.1 micromol g-1 cat.) when the irradiation time of about 360 min.Chapter 5 described a simple colloidal crystal templating method to synthesis of the hierarchically porous TiO2/graphitic carbon microspheres (TiO2/GCM). The materials possessing the highest cycling performance and discharge capacity was found through changing the content of TiO2. X-ray diffraction (XRD), nitrogen adsorption-desorption (BET), scanning electron microscopy (SEM), transmission electron microscope (TEM) and thermogravimetric (TG) analysis techniques were used to characterize the sample. The hierarchically porous composites generally have BET surface areas in the range of 97.97-198.75 m2 g-1 total pore volumes of 0.22-0.36 cm3 g-1 and the average diameter of ～5.15, ～7.87 and ～41.95 nm. From electrochemical performance results, The electrochemical tests exhibit that the 20TiO2/GCM composite show more excellent reversibility and cyclability than other proportion of composite materials. At 0.5C, the reversible discharge capacities are about 179,189,176,144 mAh g-1 for TiO2/GCM (x= 10,20,30,40), and the retention is 88.8,96.2,73.3,85.4%, respectively.Chapter 6 described a simple colloidal crystal templating method to hierarchically porous metal-TiO2/graphitic carbon microspheres (M-TiO2/GCM). At 0.5C, the reversible discharge capacities are about W-TiO2-GCM: ～ 213 Sn-TiO2-GCM: ～195 mAh g-1, Ni-TiO2-GCM: ～220 mAh g-1, Co-TiO2.GCM: ～ 75 mAh g-1, Ce-TiO2-GCM: ～243 mAh g-1,respectively. And the retention is W-TiO2-GCM: ～71.4%, Sn-TiO2-GCM: ～97.4%, Ni-TiO2-GCM: ～88.2%, Co-TiO2-GCM: ～96.0%, Ce-TiO2-GCM: ～78.6%, respectively. M-TiO2/GCM possesse the high initial discharge capacity and discharge capacity. In this work, we have developed a convenient and efficient method for the facile synthesis of hierarchically porous Metal-TiO2/graphitic carbon microspheres by colloidal crystal templating method.Chapter 6 described the conclusion and prospect.