PRA October 2016 Issue Carbon Nanotubes

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Carbon Nanotubes

Advancing industry with the power of small With carbon nanotubes (CNTs), the market is closer to having an environmentalfriendly nanomaterial that possesses ideal properties – superior strength, speed, flexibility, lightweight and thinness – all rolled into one, says Angelica Buan in this report.

Super material captured from carbon emissions Greenhouse gas emissions have been going up and are projected to spiral to 500 parts per million (ppm) at the end of this century. It is for this reason that scientists are looking at ways of reusing the massive amounts of CO2 to produce carbon nanotubes (CNTs), which are tiny tubes consisting of rolled up sheets of graphene, 10,000 times thinner than a human hair, 100 times stronger than steel but only one-sixth as heavy. In 2009, a research team from George Washington University (GWU), led by Chemistry Professor Stuart Licht, introduced a solar process that can convert atmospheric CO2 into highly valued carbon nanofibres. The solar thermal electrochemical process (STEP) makes use of the full spectrum of sunlight and thus captures more solar energy than the most efficient solar cell or photoelectrochemical processes, the group said. This breakthrough is now being eyed for application to CO2 emissions of power plants, according to the GWU researchers who initially focused the study on the combined cycle (CC) natural gas power plants, which are the most efficient kind of electrical power plant yet still emit massive amounts of CO2. The process can be undertaken by adding a molten lithium carbonate electrolyser to a conventional CC plant, creating a CC carbon nanofibre (CC CNF) plant. Using electrolysis, CO2 is split into oxygen gas and solid CNFs; and adding in small quantities of nickel, causes CNFs to be hollow, forming CNTs.

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To make sure that it is feasible, in a new study, the same researchers performed a thermodynamic assessment of the proposed CC CNF plant. They found that the concept is economically feasible and even improves the power plants' energy efficiency. Using the new method, the researchers also estimate that it would cost just US$2,000/tonne to produce CNTs, which is less than 1% of current production costs. In view of this, the researchers are working to build and implement the technology rapidly. High-valued commodity CNTs are normally categorised as either singlewall nanotubes (SWNT), with a diameter of about a nanometre; or multi-wall nanotubes (MWNT), with diameter ranging from 5 to 50 nanometres. The basic materials used to produce CNTs are iron, cobalt, hydrogen, ceramic catalysts and gases such as methane and acetylene hydrogen.

SWCNT

MWCNT

SWCNT and MWCNT growth is promising

CNT’s increasing adoption in end-use industries including polymers, electronics, energy, marine, aerospace and automotive, is driving its growth projected to reach an average of US$3.4 billion by 2022, as forecast by Grandview Research, projecting consumption to exceed 20,000 tonnes through the forecast period. By 2024, the CNT market is anticipated to balloon past US$ 8.1 billion, according to latest research report by Global Market Insights.


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