天然纳米管状矿物对模板中孔炭结构调制机理研究

Due to high surface areas, large pore volumes, and chemical inertness, porous carbon has been used in many industries. However, Only micro-porous structure can be produced by the traditional method in normarl porous carbon materials. Without large regular porous structure, normal porous carbon materials cannot separate efficiently the large molecules, and adsorb the normal bacteria while using as the merchant medical filter.With high surface areas, limited pore width, and regular mesoporous structure, mesoporous carbon materials are potentially applied in catalysts, electrodes and hydrogen storage systems, show many advantages as medical adsorbents particularly for the large molecules. Mesoporous carbon material will be prepared by using cheap natural tubular mineral materials (for examples, halloysite, brucite, serpentine, attapulgite and etc.) as template in the project. On the base of the characterization of the microstructure and properties of natural tubular mineral materials and resultant template carbon materials by the advanced techniques (for instance, X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (TEM), Infrared and Raman microprobe spectrometry and etc.), the formation mechanism of mesoporous carbon materials, the conduction and carbonization mechanism of carbon precursor in natural tubular mineral will be detected and discussed. Pore structure will be characterized by nitrogen adsorption. On the base of analyses and calculation of the parameters of microstructure and properties of natural tubular mineral materials and resultant template carbon materials, the relationships model among parameters of microstructure, properties and formation conditions could be established on the fundamental experiments and orthogonal tests. The electrical properties and medical adsorb properties of resultant template carbon materials will be detected. Due to limited pore width, and regular mesoporous structure, cheap natural minerals could be an ideal template for preparation of mesoporous carbon materials at low cost. Their microstructure of natural tubular mineral might be copied, and inherited in mesoporous carbon materials, then built the mesoporous structure in the resultant template carbon materials. It is possible to produce efficiently and economically good mesoporous carbon materials with high surface areas, limited pore width, and regular mesoporous structure by template method by using rich and cheap natural tubular mineral materials as templates. This research will be helpful for natural mineral utilization and beneficial for new porous carbon materials production.

传统多孔炭的孔径以微孔为主，对大分子吸附分离效果差，用作商业医学用途时不仅去除了有毒物质，人体正常血细胞也会吸附过滤掉。中孔炭材料的孔道结构规则、比表面积高、孔径分布窄，对大分子吸附分离有独特优势，在储能、医药等领域有广阔应用前景。本课题采用天然纳米管状矿物（埃洛石、纤水镁石、纤蛇纹石、凹凸棒石等）作为模板对合成炭材料结构进行调控，试图研制特殊结构纳米炭如弯曲炭卷、中孔炭。采用先进电子显微技术等手段，在分子水平上研究天然纳米管状矿物、以及合成炭材料的微结构和性状，通过正交实验等研究纳米管矿物、合成炭材料的结构参数、性能、形成条件的关系，研究矿物模板分子结构炭材料结构的控制机理，探索天然纳米管状矿物对合成炭材料结构的调控机理。研究以天然纳米管状矿物作为模板合成炭材料的物理化学性能，包括中孔炭的电学、医学性能等，有可能获得性价比良好的炭材料，对炭材料制备和矿物应用有重要科学意义和应用价值。

本项目以天然纳米管状矿物（埃落石）和纳米纤维矿物（纤水镁石、纤蛇纹石）为模板，蔗糖为碳源，合成了蔗糖基纳米矿物模板中孔炭, 中孔率很高，超过90%。采用电子显微镜等手段对其进行了形貌、结构分析，以天然纳米管埃洛石矿物为模板合成了“壳-核”结构的中孔炭研究。以天然纳米纤维矿物纤水镁石、纤蛇纹石为模板合成了管状结构、三维联通孔道结构的碳材料。研究发现矿物的结构、化学成分、合成条件都对模板炭的合成有影响。通过调控模板类型、模板与碳源的比例，可以调控炭材料的孔结构分布、比表面积等，进而影响模板炭的电化学性能。合成天然纳米纤维矿物（纤水镁石、纤蛇纹石）模板中孔炭作为锂、钠离子电池负极时，具有优异储能性质。锂离子电池充电比容量分别可达到 480.2 mAh/g、376.8 mAh/g，均高于商业化石墨负极，且远高于酚醛树脂基介孔炭球(74.3 mAh/g)。钠离子电池充电比容量分别可达到 134.4 mAh/g、120.1 mAh/g，也高于酚醛树脂基介孔炭球的 74.3 mAh/g。对比分析发现空心的纳米管状矿物（埃落石）比实心的纳米纤维矿物（纤水镁石、纤蛇纹石）作为模板制备的中孔炭材料比电容存在差异，可能与孔结构分布有关。基于成分结构研究结果，设计了三维核壳结构纳米复合材料，作为储锂材料时，具有优异的储锂容量、倍率性能和循环性能，电流密度为500mA/g时容量达到1055mAh/g，150 次充放电循环之后没有衰减，有望作为负极材料用于下一代高能量锂离子电池中。天然纳米矿物模板中孔炭有可能成为新一代高性价比的储能材料。