已有 6925 次阅读2017-7-20 22:51|个人分类:新科技|系统分类:论文交流|太阳能, CO2
清理CO2排放可创造价值数十万亿美金的利润
诸平
Fig. 1. Schematic representation of new synergistic pathways to form a high yield of macroscopic length CNT “wool” by electrolysis in molten carbonate. Middle: Prior C2CNT syntheses were dependent on a zinc coated steel cathode, a pure Ni anode, and a low current pre-electrolysis activation step. An intermediate, new C2CNT electrolysis removes the requirement of a zinc coating leading to the exploration of a variety of new cathode substrates. Right side: The optimized C2CNT pathway utilizes Monel cathodes and Nichrome anodes, molten electrolyte equilibration for 24 h, and the electrolysis is conducted directly without pre-electrolysis activation steps. This pathway produces a high yield of macroscopic length CNT wool. Left side: experimental cell configuration used in these C2CNT experiments. Larger cells are shown in sect. IV of Ref. [27].
Fig. 2. Top: SEM of product formed in the initial electrolysis stages at the Monel cathode/equilibrated electrolyte interface. Bottom: Carbonate electrolytic growth model of carbon nanotubes from CO2. The mechanism of electrolytic synthesis of CNTs had not been previously elucidated and here is based on the layered graphene observation observed in the top of the figure, and our previous SEM, EDX, TEM, chemical balance (the oxide buildup when CO2 is excluded), DFT calculations, and isotopic evidence. This proposed tip (left) or base (right) mechanism occurs at the solid/liquid (molten carbonate) interface, and transforms CO2 into CNTs. The mechanisms are analogous to the CVD growth mechanism, which instead occurs at the solid/gas, interface, and transforms organics, rather than CO2, into CNTs.
Fig. 3. SEM of the CNT wool product produced at the cathode from CO2 during replicate syntheses of 770 °C Li2CO3 electrolysis. Electrolysis is for 18 h at 0.1 A cm−2 (1.8 Ah cm−2) between a NiChrome anode and a Monel cathode.
Fig. 4. TEM presenting the range of these C2CNT generated CNT diameters. The lower left 10 nm scale TEM presenting the inter-graphene wall spacing is from our reference [25].
据物理学家组织网（Phys.org）2017年7月19日提供的消息，美国乔治华盛顿大学（George Washington University）的化学家将煤炭等燃料燃烧产生的CO2通过使用太阳能热力站的C2CNT工艺可以将其转化为碳纳米管绒毛(如图5所示）。
研究人员将CO2转化为CNTs(CO2 to CNTs)这项新技术简称为C2CNT,希望此项技术将提供一个不争的经济诱因，从大气中去除多余的CO2。研究者经过计算,如果在一个面积相当于撒哈拉沙漠（Sahara Desert）4%的区域建立太阳能热力站,10年之内有望使大气中CO2浓度的水平减少到工业化前的水平。他们也指出,一个更现实的实施方案就是在海洋上建造太阳能发电站，因为海洋上存在更多可用的表面积。
然而,此工艺的一个缺点就是产生CNTs都是纳米级(长度小于100μm),太短无法编织成纺织品。这项新研究的主要结果是CNTs的长度超过100倍,可以取代电解槽与蒙乃尔铜镍合金一起使用的铜阴极或钢阴极。通过作这种变化和其他参数的仔细调优,研究人员制作出CNTs 的直径超过1μm和长度超过1 mm 。他们指出,针对这种产品引出另外一个实际问题:这种纳米管是否应该被归类为“纳米材料（nanomaterials）”。在任何情况下,仿绒毛碳纳米管都是有足够的长度，以满足编织成纺织品供各种应用需求。
Unusual carbon nanotube wools are introduced electrosynthesized in molten carbonate.
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C2CNT is CO2 transformation to carbon nanotubes by electrolysis in molten carbonate.
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(Air or exhaust) CO2 is the only reactant in C2CNT carbon nanotube wool synthesis.
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C2CNT product value (>100,000 US dollars) compared to cost (660 US dollars) incentivizes CO2 removal.
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CO2 becomes a useful, valuable resource rather than a greenhouse gas pollutant.
Abstract
A climate mitigation comprehensive solution is presented through the first high yield, low energy synthesis of macroscopic length carbon nanotube (“CNT”) wool from CO2 by molten carbonate electrolysis. The CNT wool is of length suitable for weaving into carbon composites and textiles. Growing CO2 concentrations, and the concurrent climate change and species extinction, can be addressed if CO2 becomes a sought resource rather than a greenhouse pollutant. Inexpensive carbon composites formed from carbon wool as a lighter metal, textiles or cement replacement comprise major market sinks to compactly store transformed anthropogenic CO2. 100×-longer CNTs grow on Monel versus steel. Monel, electrolyte equilibration, and a mixed metal nucleation facilitate the synthesis. CO2, the sole reactant in this transformation, is directly extractable from dilute (atmospheric) or concentrated sources, and the analyzed production cost of 660 US dollars per ton CNT is cost constrained only by the (low) cost of electricity. Today's market valuation of >100,000 US dollars per ton CNT incentivizes CO2 removal.
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