Formation mechanism of fullerenes

富勒烯的形成机理是富勒烯科学中最难解决的问题之一，但C60的工业化合成亟待解决，这实际上是富勒烯碳应用出现的关键障碍。在这笔赠款的任期内，我们澄清了这一机制，并提出了两种全新的、有前途的C60制备方法。我们的工作是受到来自云南省的一种新的煤样的推动，该煤样含有令人惊讶的高C60/C70浓度(挖掘后立即估计的初始浓度为0.3%)。我们发现了三件证据，表明这种特殊的煤已经暴露在冲击波中。最有力的证据是，烟尘的初级颗粒非常丰富，直径极小(直径约10纳米)。注意到最纯净和最容易获得的烟尘是商业炭黑，我们于是在我们的S…中使用了炭黑更多的附属研究。虽然炭黑中没有可测得的C60含量，但我们观察到，在聚焦电子束(冲击波的替代品)的照射下，炭黑的初级粒子被干净地转化为洋葱状的多壳层富勒烯。在透射电子显微镜中仔细检查这种转变，发现螺旋粒子作为中间体进行了干预。此外，我们还发现洋葱会变成螺旋状。我们假设螺旋电子显微镜图像代表的是形状接近洋葱的三维螺旋颗粒。构思和生成了化学模型和数值模型。这些工作最终使我们构建了一个一致的富勒烯形成机理，包括螺线的螺旋生长和螺线颗粒通过可逆的多键裂解/壳间价异构化反应/多键闭合稳定成洋葱。这一机制的成功阐明了洋葱独特构型的起源，促使我们构思了一种利用碳黑生产线生产C60的新方法。另一种新的C60生产方法是简单地将碳暴露在冲击加热下。如果冲击波是由炸药爆炸产生的，而煤是碳素材料，C60的生产可以在煤矿现场进行。该方法具有成本效益，通过减少以煤为燃料的二氧化碳排放，有助于解决环境问题，并促进和平使用炸药。文献中已经有一些例子表明，在某些条件下，冲击波会产生富勒烯而不是钻石。例如，在激波管实验中，苯受到爆炸冲击时会形成300ppm的C60。需要进行几个仔细的初步实验来验证本建议。较少

Mechanism of fullerene formation is one of the most difficult problems in fullerene science but has been urgently needed in order to develop industrially favorable synthesis of C60, which is actually a critical obstacle to the emergence of applications of fullerene carbons. During the tenure of this grant, we clarified the mechanism and proposed two entirely new and promising methods of the preparation of C60.Our work is motivated by a novel coal sample arrived from Yunnan Province, China, that contains surprisingly high concentration of C60/C70 (an initial concentration immediately after excavation estimated to be 0.3%). We found three pieces of evidence that indicate that this particular coal has been exposed to shock wave. The strongest evidence is high abundance of the primary particles of soot with extremely small diameter (ca 10 nm in diameters). Noting the fact that the purest and the most readily available soot is commercial carbon black, we thereupon used carbon black in our s … More ubsequent study. Whereas carbon black did not contain measurable amounts of C60, we observed that the primary particles of carbon blacks are cleanly converted to onion-like multi-shell fullerenes upon irradiation with focused electron beam (a substitute of shock wave). Careful examination of this transformation in TEM revealed intervention of spiral particles as the intermediate. Furthermore, we also found that onion changes into spirals. We assumed that the spiral TEM images represent 3D spiroidal particles close in shape with onions. Chemical as well as numerical models were conceived and generated. These works eventually led us to construct a consistent mechanism of fullerene formation consisting of spiral growth of spiroids and the stabilization of spiroid particles into onions by reversible multiple bond cleavage/intershell valence isomerization reactions/multiple bond closure. Success of this mechanism to elucidate the origin of unique configuration of onions encouraged us to conceive a new method of C60 production that uses the production line of carbon black.Another new method of C60 production is simply to expose carbon to shock heating. If shock wave is generated by detonation of explosives and coal is carbon materials, the production of C60 may be carried out on the coal mine site. The method is cost effective, contributes to environmental problem by reducing the CO2 emission by burning coal as the fuel, and also promotes the use of explosives for peaceful purposes. There are already some examples previously reported in the literature that indicates that somewhat shock wave will generate fullerenes in stead of diamond under some conditions. For example, in a shock tube experiment, 300 ppm of C60 was formed when benzene was subjected to detonative shock. A few careful preliminary experiments will be needed to verify the present proposal. Less