Two projects have produced elastic, ultra-light carbon foams without using a template.

Chao Gao and his colleagues at Zhejiang University in Hangzhou, China, freeze-dried solutions of carbon nanotubes and large sheets of graphene oxide, and then chemically removed oxygen to leave a conductive, elastic, solid foam (pictured with long-stemmed grass) with a density lower than that of air. These aerogels can absorb up to 900 times their own weight in oil — better than commercial absorbents.

Zongbin Zhao and Jieshan Qiu, at Dalian University of Technology in China and their colleagues have made similar, but slightly heavier aerogels, from graphene oxide sheets. Their aerogel is extremely elastic, bouncing back when compressed, so may be useful in absorbing energy and dampening vibrations for a variety of machinery. Although similarly light carbon aerogels have been made before, they have relied on template scaffolds that were later etched away, a technique that limits the size of the final structure.

Credit: CHAO GAO

Adv. Mater.; (2013)