科学家们正在将造成气候变化的二氧化碳（CO2）这种温室气体变成碳纤维。这种纤维是纳米纤维，它们可能是未来的建筑材料。

http://b263.photo.store.qq.com/psb?/V13Rrarc03mULP/9igHktDWl8tUWSLb4F6ucysMEgdICbbpEVNHbLTRc7A!/b/dAcBAAAAAAAA&bo=uAJNAQAAAAABANE! 
左边显示的是由二氧化碳生成的碳纳米管；右边是纳米纤维，上面有碳纳米管的增长亮点。 （图片由Stuart Licht提供）  

斯图尔特·利希特(Stuart Licht)是乔治·华盛顿大学(George Washington University)研究该工艺的研究小组中的首席科学家。他认为利用气体制造坚固耐用的材料最终在商业上将是可行的。

他的研究小组发现，碳纳米纤维在强度、韧性和导电性方面优于钢材。这使得它们具有广泛的用途，从电池、电器到在建筑物、飞机、汽车和运动设备中所使用的重量轻、高强度的材料。

更环保能否更便宜？

利希特在2015年介绍了他的小组的研究成果。在那以后，他的研究小组还发现，这些纳米纤维可以制成甚至更加坚固的碳纳米管。利希特说，最近的一项研究表明，天然气发电厂所排放的二氧化碳气体可以“经济化地被清除并被转化为碳纳米管”。[请见英文报道]

汽车制造商已经在使用碳纤维来代替钢材，以减轻车重。但制造碳纤维成本高昂，需要价格不菲的原材料、能源消耗和设备。而钢和铝的生产成本则较低。

尽管如此，如果碳可以从大气中大量存在的二氧化碳中高效地提取，碳纤维建材的价格就可能大幅降低。利希特说有些公司已经表示对此很感兴趣。

使用太阳能的新工艺

将二氧化碳变成碳纳米纤维需要几个步骤，并要利用可再生能源。

1. https://share.america.gov/wp-content/uploads/2016/07/nanofibers20.gif(美国国务院/ D. Thompson)

   在排放量大的地方从空气中采集二氧化碳。

2. 太阳能提供了将捕获的二氧化碳在熔融碳酸盐浴中分解所需要的高热能和电能。
3. 二氧化碳在接触带电电极时发生溶解。
4. 碳纳米纤维在钢电极上积聚。

利希特认为，这一工艺可能大规模完成，这将大大减少人类活动所产生的有害的二氧化碳排放。

环境科学家马丁·斯图特(Martin Stute)参与了将二氧化碳存储在石头中的突破性研究。他说，早期的碳纳米纤维研究是令人鼓舞的。 “[碳纳米纤维]有希望用在建筑施工中，以取代钢和铝。”

下一步是什么？利希特的研究小组是竞争“碳X大奖”（Carbon Xprize）的团队之一，该奖项的目的是推动创新技术，通过将二氧化碳转化成为有价值的商业产品，来减轻气候变化的影响。 

Castles in the air? Carbon dioxide could produce building materials.

Imagine if all the carbon dioxide emitted by smokestacks and motor vehicles could be used to build skyscrapers instead of polluting the air. It could become a reality, if a new process goes mainstream.

Scientists are converting carbon dioxide (CO2),  a greenhouse gas that contributes to climate change, into carbon threads. The threads are nanofibers, and they may be the building blocks of the future.

Stuart Licht, lead scientist on a George Washington University team researching this process, thinks making a strong, durable material from thin air can eventually become commercially viable.

His team found that carbon nanofibers are superior to steel in strength, flexibility and conductivity. That makes them useful for many applications — from batteries and electronics to lightweight, high-strength materials used in buildings, aircraft, cars and athletic equipment.

Can greener be cheaper?

Licht presented his team’s findings in 2015. Since then, his team discovered that these nanofibers can grow into an even stronger formation: carbon nanotubes. A recent study showed that CO2 gas from natural gas power plants can be “economically removed and converted to carbon nanotubes,” Licht said.

Automobile manufacturers already use carbon fiber in place of steel to lighten vehicle weight. But manufacturing carbon fiber is expensive, requiring costly source materials, energy consumption and equipment. Steel and aluminum are cheaper to produce.

Still, if carbon can be efficiently harvested from the abundant amounts of CO2 in the atmosphere, the price tag for carbon fiber–construction could plummet. And Licht says companies have already expressed interest.

A new process uses solar power

It takes a few steps and renewable energy to transform CO2 to carbon nanofibers.

1. https://share.america.gov/wp-content/uploads/2016/07/nanofibers20.gif(State Dept./ D. Thompson)

   CO2 is captured from the air where emissions are heavy.

2. Solar energy provides the intense heat and electricity required to break down captured CO2 in a molten carbonate bath.
3. The CO2 dissolves when it contacts electrified electrodes.
4. The carbon nanofibers accumulate on the steel electrode.

Licht thinks the process could be done on a scale that would greatly reduce the amount of harmful CO2 emissions caused by human activity.

Environmental scientist Martin Stute, himself involved in breakthrough research to capture CO2 in stone, said that early carbon nanofiber research is encouraging. “There is hope that [carbon nanofibers] can be used in building construction to replace steel and aluminum.”

What’s next? The Licht research group is among teams competing for the Carbon Xprize, which seeks to drive innovative technologies that reduce the impact of climate change by converting CO2 into valuable commercial products.