For two hours the group used chemical vapour deposition to grow the long nanotube on a silica substrate. The team managed to improve their technique so much as they discovered that CNT growth is controlled by kinetics and that catalyst activity is the most important factor. If the catalyst has a high probability of failing after 1mm growth, the CNTs grown will be short. Optimising the conditions to reduce the ‘catalyst’s deactivation probability’ meant the CNTs grew longer and, in one instance, over half a metre long.
CNTs are strong and are often suggested as materials for armour and other applications, but the question of how to grow long, controlled CNTs has been a matter of debate. With the latest work from Fei Wei’s group perhaps CNTs will soon break the metre mark.