Gram-scale bottom-up flash graphene synthesis
Gram-scale bottom-up flash graphene synthesis
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DOI：
10.1038/s41586-020-1938-0
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发表时间：
2020-01-27
期刊：
影响因子：
64.8
通讯作者：
Tour, James M.
中科院分区：
文献类型：
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作者：
Luong, Duy X.;Bets, Ksenia V.;Tour, James M.
大多数大规模石墨烯是通过自上而下的方法生产的，剥离石墨，这通常需要大量的溶剂和高能混合，剪切，超声处理或电化学处理（1-3）。尽管石墨化学氧化成氧化石墨烯促进了剥离，但它需要苛刻的氧化剂，并且在随后的还原步骤（3，4）之后留下具有缺陷穿孔结构的石墨烯。如果通过化学气相沉积或先进的合成有机方法进行，则高质量石墨烯的自下而上合成通常限于超少量，或者如果在本体溶液中进行，则其提供充满缺陷的结构（4-6）。在这里，我们表明，廉价碳源（例如煤炭、石油焦、生物炭、炭黑、废弃食品、橡胶轮胎和混合塑料废物）的闪焦耳加热可以在不到一秒的时间内提供克级数量的石墨烯。该产品，命名为闪光石墨烯（FG）后，用于生产它的过程中，显示出乱层排列（即，小秩序）之间的堆叠石墨烯层。FG合成不使用熔炉，也不使用溶剂或反应气体。产率取决于来源的碳含量;当使用高碳来源，如炭黑、无烟煤或煅烧焦炭时，产率可达80%至90%，碳纯度大于99%，不需要提纯步骤。拉曼光谱分析显示FG的低强度或不存在D带，表明FG具有迄今为止报道的石墨烯的最低缺陷浓度，并证实了FG的乱层堆叠，其明显区别于乱层石墨。FG层的无序取向有利于其在复合材料形成期间混合时的快速剥离。FG合成的电能成本仅为每克约7.2千焦，这使得FG适用于塑料、金属、胶合板、混凝土和其他建筑材料的散装复合材料。利用廉价碳源的闪焦耳加热，无需熔炉、溶剂或反应气体，即可在一秒内生产出克级数量的高质量石墨烯。
Most bulk-scale graphene is produced by a top-down approach, exfoliating graphite, which often requires large amounts of solvent with high-energy mixing, shearing, sonication or electrochemical treatment(1-3). Although chemical oxidation of graphite to graphene oxide promotes exfoliation, it requires harsh oxidants and leaves the graphene with a defective perforated structure after the subsequent reduction step(3,4). Bottom-up synthesis of high-quality graphene is often restricted to ultrasmall amounts if performed by chemical vapour deposition or advanced synthetic organic methods, or it provides a defect-ridden structure if carried out in bulk solution(4-6). Here we show that flash Joule heating of inexpensive carbon sources-such as coal, petroleum coke, biochar, carbon black, discarded food, rubber tyres and mixed plastic waste-can afford gram-scale quantities of graphene in less than one second. The product, named flash graphene (FG) after the process used to produce it, shows turbostratic arrangement (that is, little order) between the stacked graphene layers. FG synthesis uses no furnace and no solvents or reactive gases. Yields depend on the carbon content of the source; when using a high-carbon source, such as carbon black, anthracitic coal or calcined coke, yields can range from 80 to 90 per cent with carbon purity greater than 99 per cent. No purification steps are necessary. Raman spectroscopy analysis shows a low-intensity or absent D band for FG, indicating that FG has among the lowest defect concentrations reported so far for graphene, and confirms the turbostratic stacking of FG, which is clearly distinguished from turbostratic graphite. The disordered orientation of FG layers facilitates its rapid exfoliation upon mixing during composite formation. The electric energy cost for FG synthesis is only about 7.2 kilojoules per gram, which could render FG suitable for use in bulk composites of plastic, metals, plywood, concrete and other building materials.Flash Joule heating of inexpensive carbon sources is used to produce gram-scale quantities of high-quality graphene in under a second, without the need for a furnace, solvents or reactive gases.