A greener way to grow carbon nanotubes
Given their size, strength and electrical properties, carbon nanotubes — tiny, hollow cylinders made of carbon atoms — hold promise for a range of applications in electronics, medicine and other fields. Despite industrial development of nanotubes in recent years, however, very little is known about how they form or the environmental impacts of their manufacture.It turns out that one process commonly used to produce carbon nanotubes, or CNTs, may release several hundred tons of chemicals, including greenhouse gases and hazardous air pollutants, into the air each year. In a paper published last week on the ACS Nano website, the researchers report that in experiments, removing one step in that process — a step that involves heating carbon-based gases and adding key reactive “ingredients” — reduced emissions of harmful by-products at least tenfold and, in some cases, by a factor of 100. It also cut the amount of energy used in...